US3616273A - Nitrogen determination and apparatus therefor - Google Patents

Nitrogen determination and apparatus therefor Download PDF

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US3616273A
US3616273A US717889A US3616273DA US3616273A US 3616273 A US3616273 A US 3616273A US 717889 A US717889 A US 717889A US 3616273D A US3616273D A US 3616273DA US 3616273 A US3616273 A US 3616273A
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hydrocracking
organic material
nitrogen
ammonia
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Itsumi Jack Oita
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Standard Oil Co
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
    • G01N31/002—Determining nitrogen by transformation into ammonia, e.g. KJELDAHL method
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/11—Automated chemical analysis
    • Y10T436/115831—Condition or time responsive
    • Y10T436/116664—Condition or time responsive with automated titrator
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00—Chemistry: analytical and immunological testing
    • Y10T436/17—Nitrogen containing
    • Y10T436/176152—Total nitrogen determined

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  • My invention relates to a method and apparatus for automatic quantitative analysis. More specifically, it relates to an improved method and apparatus for analyzing the nitrogen composition of nitrogen-containing materials.
  • my invention relates to a method and apparatus for hydrocracking nitrogen-containing organic materials, hydrogenating the nitrogen contained therein to ammonia, and measuring the ammonia present in the material from which the original nitrogen composition of the material can be determined.
  • Coulometric titration means are particularly advantageous and convenient for the required ammonia analysis.
  • the Dumas method involving the oxidation of nitrogen compounds over copper oxide and the subsequent reduction of the nitrogen present to elemental nitrogen, requires less time for analysis but is less sensitive.
  • the ter Meulen method involves the catalytic production of ammonia from nitrogen-containing compounds and the subsequent measurement of the ammonia formed. This method offers the advantages of both high sensitivity and relatively short analysis times.
  • the drawback to the ter Meulen method, up to this time, is that it has not been adaptable to the analysis of higher boiling nitrogen-containing materials.
  • the ter Meulen method converts nitrogen to ammonia by hydrogenation over a nickel-on-magnesia catalyst. lnvestigations show that at temperatures of from about 600 to about 750 F., the alkaline nickel-on-magnesia catalyst traps and holds acidic gases such as H 8 and HCl. Then, at temperatures above 750 F these acidic gases are slowly released and pass with the ammonia to the device used in measuring the ammonia present. The gases may then interfere with the required ammonia analysis. Since temperatures in excess of l,000 F.
  • the nickelon-magnesia catalyst would necessarily be at a temperature at which the acidic acids are released and thus such high boiling samples cannot be analyzed using the basic ter Meulen method.
  • Prior art nitrogen analyzers have often had difficulty in analyzing viscous, nitrogen-containing samples because of problems encountered in introducing the sample into the analyzer.
  • Conventional methods of introducing nitrogen-containing samples into nitrogen analyzers are by drawing the sample into a long needle syringe, introducing the needle of the syringe into a permeable septum system built into the analyzer, and injecting the sample through the needle into the analyzer. Viscous, nitrogen-containing samples will not flow easily through the relatively small bore syringe needle and, therefore, such a method often becomes impractical
  • My invention includes a method and apparatus for eliminating this problem.
  • a suitable catalyst for hydrocracking the nitrogen-containing material comprises rhodium on either a silica-alumina base, a molecular sieve base or a base comprising mixtures of silica-alumina and zeolitic molecular sieve material.
  • the hydrocracking catalyst should be at a temperature of about l,400 F. and if a bed of nickel granules is also used, this bed can also be at about 1,400 F. or somewhat lower.
  • the carrier gas acts to dilute the sample and to sweep it through the zones of hydrocracking and Although any nonnitrogen-containing inert gas may be used as the carrier, it is most advantageous to use hydrogen gas for this purpose since hydrogen is required in the hydrocracking and hydrogenation steps. Humidifying the hydrogen gas is effective in inhibiting the coking of the hydrocracking catalyst.
  • the apparatus for determining the nitrogen content of a nitrogen-containing material which uses the method of my invention comprises a reactor, including zones for vaporizing, hydrocracking and hydrogenating the sample and a means for analyzing the reactor effluent for nitrogen contained therein.
  • a reactor including zones for vaporizing, hydrocracking and hydrogenating the sample and a means for analyzing the reactor effluent for nitrogen contained therein.
  • Various means of analyzing the nitrogen are possible but one that has been found most convenient comprises an automatic coulometric titrator as described in U.S. Pat. No. 3,461,042.
  • Means for introducing hydrogen into the reactor must be provided and preferably this means should also include provisions for humidifying and heating the hydrogen gas.
  • the nitrogen material should be encapsulated in a substance which melts at a temperature no higher than the temperature encountered in the vaporizing zone of the nitrogen analyzer.
  • the encapsulated nitrogen-containing material is then introduced into the vaporizing zone.
  • the encapsulated material may be introduced into the analyzer through a vapor lock" zone comprising a chamber communicating alternatively with the nitrogen analyzer vaporizing zone and the exterior of the analyzer. In this manner an operator may insert the samplecontaining capsule into the chamber, interrupt the communication between the exterior of the analyzer and the chamber, and initiate communication between the chamber and the vaporizing zone of the nitrogen analyzer so that the capsule is introduced into the vaporizing zone.
  • FIG. 1 is a schematic view of the complete nitrogen determination system showing a hydrogen humidifier, a reactor, and a titration cell.
  • FIG 2 is an enlarged view of the reactor, partially in section, showing the vaporization, hydrocracking and hydrogenation zones, as well as an improved sample inlet means.
  • the method of my invention for automatically determining the nitrogen content of an organic material involves the steps of passing the organic material through a hydrocracking zone to crack the organic material into lower molecular weight components, converting the nitrogen in the material to ammonia by hydrogenation and determining the quantity of ammonia produced.
  • the hydrocracking zone includes a suitable hydrocracking catalyst such as one comprising rhodium on a silica-alumina base, a molecular sieve base or on a base comprising a mixture of silica-alumina and zeolitic molecular sieve material. It has been found that a hydrocracking catalyst containing about 0.6 percent rhodium is effective.
  • the nitrogen is converted to ammonia by passing the hydrocracked material through a hydrogenation zone containing a suitable hydrogenation catalyst.
  • a suitable hydrogenation catalyst which has been found to be suitable comprises nickel on a magnesia base.
  • the nitrogen-containing sample is mixed with a carrier gas such as hydrogen prior to being passed through the hydrocracking and hydrogenation zones.
  • humidification of the hydrogen gas carrier has proven satisfactory.
  • my method comprises introducing the nitrogen-containing material into a vaporizing zone, mixing the vaporized material with humidified hydrogen, passing the vaporized material and humidified hydrogen through a hydrocracking zone at a temperature in the range of between about l,400 F. and about l,440 F., passing the vaporized hydrocracked product and humidified hydrogen through a bed of nickel granules at a temperature in the range of between about 1,400 F. and l,440 F., passing the hydrocracked material and humidified hydrogen through a hydrogenation zone at a temperature in the range of between about 680 F. and about 750 F.
  • the nitrogen-containing material is conveniently introduced into the vaporizing zone by encapsulating it in a material which melts at a temperature no higher than that encountered within the vaporizing zone and introducing the encapsulated material into the vaporizing zone through a vapor lock. Less viscous samples of nitrogencontaining material can be introduced into the vaporizing zone by means of the syringe and septum technique described above.
  • the apparatus ofmy invention for determining the nitrogen content of an organic material, comprises a reactor including a vaporizing zone, a hydrocracking zone, a hydrogenation zone, and an analyzing means in communication with said reactor for quantitatively detecting the presence of ammonia.
  • the reactor provides for the passage of the nitrogen-contain ing sample sequentially through the vaporizing, hydrocracking and hydrogenation zones, and further provides for the passage of a sample to the analyzing means.
  • the vaporizing zone includes a heating means sufficient to permit the passage of the nitrogen-containing sample into the hydrocracking zone as a vapor. Accordingly, the heating means should be capable of heating the sample to a temperature of at least about 1,400" F.
  • the hydrocracking zone must contain a hydrocracking catalyst, such as the conventional silica-alumina base catalyst, or the newer molecular sieve-type hydrocracking catalyst.
  • a hydrocracking catalyst such as the conventional silica-alumina base catalyst, or the newer molecular sieve-type hydrocracking catalyst.
  • the incorporation of minor amounts of rhodium on either the silica-alumina base catalyst or the molecular sieve catalyst provides improved hydrocracking performance.
  • About 0.6 percent rhodium has been found to be a suitable amount to incorporate in the hydrocracking catalysts of my invention.
  • the hydrogenation zone includes a suitable hydrogenation catalyst such as is described in 24 Analytical Chemistry 1755-1756. Modifications of that particular catalyst or other hydrogenation catalysts might also be used in the hydrogenation zone of myapparatus.
  • the reactor should also include provisions for the introduction of a carrier gas to be mixed with the nitrogen-containing sample material prior to the hydrogenation zone, which successively sweeps the sample through the reactor and into the analyzing means.
  • a carrier gas for use in my invention is hydrogen because it is needed in the hydrocracking and hydrogenation zones of the reactor and is also used for the determination of nitrogen when using the preferred coulometric titrating apparatus.
  • the hydrogen carrier gas should be humidified and heated to about 200 F. before being introduced into the reactor in order to inhibit coking of the hydrocracking catalyst.
  • This inlet means includes a vapor tight chamber capable of communication alternatively with the reactor vaporizing zone and the exterior of the apparatus.
  • An embodiment of such an inlet means comprises a substantially vertical conduit in communication with the reactor vaporizing zone.
  • the conduit contains a plug mounted for rotation within the conduit flow passage so as to prevent the passage of material through the conduit.
  • a well or other type of receptacle is present within the plug and adapted to receive a sample container introduced into the conduit. Due to the substantially vertical nature of the conduit, the sample container is held within the well by gravitational forces.
  • Rotation of the plug within the conduit reorients the well from its container-receiving position to a position such that the well communicates with the reactor vaporizing zone. Again, because of the substantially vertical nature of the conduit, any sample container present within the well drops from the well and is introduced into the reactor vaporizing zone. It is evident the plug must be properly seaied within the conduit flow passage to prevent the escape of carrier gas from the reactor.
  • the tube has mounted within it a large bore stopcock.
  • a stopcock made of Teflon would be most suitable, although one made from Pyrex glass would also be satisfactory.
  • the stopcock has its bore sealed at one end by the presence of a septum, preferably composed of silicone rubber. This septum prevents material from passing through the stopcock bore, but is also of such a nature that it can be pierced by a hypodermic needle and still remain substantially vapor tight once the needle is removed.
  • a sample container receptacle is formed by the walls of the stopcock bore and the septum.
  • the stopcock is first turned so that the unsealed end of the bore is in communication with the upper end of the tube.
  • a container holding the sample material sized so as to fit completely within the container receptacle, is inserted into the tube so that it drops into the container receptacle.
  • the stopcock is merely turned about 180. This permits the sample container to fall from the receptacle into the reactor vaporizing zone. It is essential that the sample container be composed of a material which melts at the temperature encountered within the vaporizing zone so that the sample can be vaporized, mixed with the carrier gas and passed through the reactor.
  • any apparatus for ammonia determination may be used as the analyzing means of my invention.
  • This includes, but is not limited to, colorimetric and acidimetric analyzers.
  • a particularly desirable type of analyzing means which is conveniently adapted for use with my invention is the automatic coulometric titration apparatus described in U.S. Pat. No. 3,461,042.
  • the automatic coulometric titration apparatus is particularly convenient for use with my invention, not only because of its sensitivity and rapidity of analysis, but also because the hydrogen gas required is readily available as the carrier sweep gas. Since the automatic coulometric titration apparatus and method are fully described in the above-mentioned patent applications, there is no need to repeat such a description here.
  • FIGS. 1 and 2 The method and apparatus of this invention may be more fully understood by referring to FIGS. 1 and 2. It is understood that in FIG. 1, all connecting lines are of% inch copper tubing unless other wise noted.
  • a source of hydrogen gas is connected to water tank 11 of humidifier 12 via line 13 and valve 14.
  • Bypass line 15, using valve 150 as a bypass control, is connected to line 13 ahead of valve 14 to permit the flow of dry hydrogen gas around water tank 11.
  • Water tank 11 is wrapped with heating tape (not shown) to permit the heating of the water contained therein to a temperature of at least 200 F.
  • Line 16 extends from the outlet of water tank 11 and connects to Swagelock joint 18.
  • Bypass line 15 connects to outlet line 16 ahead ofhydrogen flow valve 17.
  • Reactor 19 consists of a is-inch O.D. quartz U-shaped tube having a sample inlet 20 attached to vertical arm 19a.
  • Sample inlet 20 is of Pyrex glass and contains a large 8 mm. bore Pyrex stopcock 21.
  • Sample inlet 20 is attached to reactor 19 by graded seal 22.
  • Graded seal 22 is required in order to bond Pyrex sample inlet 20 to quartz vertical arm 19a.
  • Reactor 19 is provided with hydrogen inlet 23 at a point somewhat below graded seal 22. Hydrogen inlet 23 connects with Swagelock joint 18 by butyl rubber tubing joint 24 and line 25. Tubing joint 24 is needed to provide sufficient flexibility to minimize breakage of hydrogen inlet 23 when connecting or disconnecting humidifier 12 from the reactor.
  • Vaporizing zone 26 is in the horizontal portion of reactor 19 and is provided with a resistance wire heating means 29. Heating means 29 should be capable of providing temperatures of at least 1,030 F. within vaporizing zone 26.
  • Hydrocracking zone 27 and hydrogenation zone 28 are both located in vertical arm 31 of reactor 19.
  • Hydrocracking catalyst 30 is present within hydrocracking zone 27 and comprises 0.6 percent rhodium on a silica-alumina cracking catalyst support. This catalyst is prepared by dissolving the calculated amount of rhodium chloride in the maximum amount of water (predetermined by titration) that the silicaalumina support can absorb without appearing "wet.” The rhodium chloride solution and silica-alumina support are mixed, air-dried, and pelleted to 56-inch pellets. These pellets are calcined at l,020 F. for 2 hours and then ground to 16-35 mesh.
  • hydrocracking catalyst 30 is a bed of reagent grade nickel granules 32, also having a size of from 16 to 35 mesh.
  • Hydrocracking zone 27 is provided with a heating means, such as a furnace (not shown) which keeps the hydrocracking catalyst 30 and nickel granules 32 at about l,400 F. This furnace should be capable of maintaining hydrocracking catalyst 30 and nickel granules 32 at a temperature of about l,650 F.
  • a hydrogenation catalyst 33 comprising nickel on a magnesia base, is located in hydrogenation zone 28, which is above hydrocracking zone 27.
  • Hydrogenation zone 28 is provided with a heating means, such as a furnace (not shown), which ordinarily keeps hydrogenation catalyst 33 at a temperature of about 680 F. This furnace should be capable of heating hydrogenation catalyst 33 to about l,100 F.
  • Outlet 34 of reactor 19 connects to inlet 35 of titration cell 36 via glass connection line 37.
  • Titration cell 36 electrically connects to coulometer 38, which in turn electrically connects to recorder 39.
  • Titration cell 36 contains a suitable electrolyte such as aqueous sodium sulfate at a pH of about 5.95. Such an electrolyte may be prepared by dissolving about 5 g. of reagent grade sodium sulfate in 1 liter of ion-exchanged water.
  • tin sample container 40 is about 5X13 mm. in size.
  • Table 1 shows results of analyses performed with lubricating oils or base stock lubricating oils.
  • the nitrogen content in the samples ranged from about 50 p.p.m. to over 1,000 ppm.
  • the data presented in table 2 are the results of similar analyses on oil additives and miscellaneous oils. These samples had nitrogen contents much higher than those shown in table 1.
  • Hydraulic fluid 0.0802 0.0800 02 Except as indicated, all comparison runs were made using the Kjeldahl method. Two comparison runs were made using the Dumas method because the compounds being tested contained nitrogen-nitrogen linkages and therefore could not be analyzed by the Kjeldahl method. All samples analyzed in tables l and ll were similar in viscosity and boiling points.
  • a method for automatically determining the nitrogen content of an organic material by the steps of converting the nitrogen to ammonia by means of passing the organic material through a hydrogenation zone containing a nickel-on-magnesia catalyst and then determining the quantity of ammonia present, the improvement comprising first introducing the organic material into a vaporizing zone, mixing the vaporized organic material with hydrogen, passing the vaporized material and hydrogen through a hydrocracking zone containing a hydrocracking catalyst at a temperature sufficient to hydrocrack the organic material, and then passing the vaporized hydrocracked product to said hydrogenation zone.
  • hydrocracking catalyst comprises rhodium on a molecular sieve base.
  • hydrocracking catalyst comprises rhodium on a silica-alumina base.
  • a method for automatically determining the nitrogen content of an organic material comprising:
  • step (d) Coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic materi al.
  • hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base.
  • hydrocracking catalyst comprises 0.6 percent rhodium on a silica-alumina base.
  • An apparatus for determining the nitrogen content of an organic material comprising:
  • a vaporizing zone including a heating means for vaporizing said organic material
  • a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about 1,400 F. and 1,440 F;
  • Analyzing means for quantitatively detecting the presence of ammonia said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially:
  • effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
  • said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
  • said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on silica-alumina, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
  • the apparatus of claim 11 further including a hydrogen supply means in fluid communication with said reactor and adapted to supply hydrogen to said reactor at a point within said reactor prior to said hydrocracking zone.
  • a method for automatically determining the nitrogen content of an organic material comprising:
  • step (d) coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic material.
  • An apparatus for determining the nitrogen content of an organic material comprising:
  • a vaporizing zone including a heating means for vaporizing said organic material
  • hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about l,400 F. and L440 F; and 3. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680 F. and 715F.; and
  • a substantially vertical conduit having an upper end, a lower end which is in communication with said vaporizing zone, and an interior passageway along its longitudinal axis;
  • a plug having a well, said plug being rotatably mounted within said passageway, said well being in registration with the passage of said conduit so that as said plug is rotated within said bore, the well alternatively communicates with the upper end of said conduit and the lower end of said conduit;
  • analyzing means for quantitatively detecting the presence of ammonia said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially:
  • effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
  • An apparatus for determining the nitrogen content of an organic material comprising;
  • a vaporizing zone including a heating means for vaporizing said organic material
  • a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about l,400 F. and 1440 F.;
  • a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680 F. and 7 l 5 F.;
  • a substantially vertical tube having an upper end and a lower end which is in communication with said vaporizing zone, and a passageway along its longitudinal axis, and a hole passing through the surface of said tube communicating with the passageway of said tube;
  • a stopcock mounted for rotation within said hole in said tube, said stopcock at all times preventing flow through the passageway in said tube, said stopcock having a flow passage, one end of which is sealed;
  • analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially;

Abstract

A method and apparatus for quantitatively determining the nitrogen content of organic materials, especially those organic materials having boiling points in excess of about 450* F. The method involves hydrocracking the organic material, hydrogenating the nitrogen to ammonia, and measuring the quantity of ammonia present, which may then be related to the original nitrogen composition.

Description

United States Patent [72] Inventor Itsumi Jack Oita Chicago, Ill. [21] Appl. No. 717,889 [22] Filed Apr. 1, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Standard Oil Company Chicago, Ill.
[54] NITROGEN DETERMINATION AND APPARATUS THEREFOR 20 Claims, 2 Drawing Figs.
[52] U.S. Cl 204/1 T, 23/230 l-lC, 23/230 M, 23/232 E, 23/253 R, 23/254 E, 204/195 [51] Int. Cl ..G0ln 27/42 [50] Field of Search 204/1.l, 195; 23/230, 232, 253, 254 E; 208/97, 111
[56] References Cited UNITED STATES PATENTS 3,438,887 4/1969 Morris et al. 208/111 X HUMIDIFIER I l 7 3,468,788 9/1969 Wilkinson 208/111 X 3,503,871 3/1970 Gladrow et al. 208/111 3,461,042 8/1969 Martin et a1. 204/1 OTHER REFERENCES Ronald L. Martin, Analytical Chemistry, Vol. 38, No. 9, pp. 1209- 12l3,(l966).
Dohrmann Tech. Bulletin 508 Dohrmann Tech. Bulletin 522 Journal ofGas Chromatography, p. 9A, July 1966.
Primary Examiner-G. L, Kaplan Attorneys-Arthur G. Gilkes and William T. McClain ABSTRACT: A method and apparatus for quantitatively determining the nitrogen content of organic materials, especially those organic materials having boiling points in excess of about 450 F. The method involves hydrocracking the organic material, hydrogenating the nitrogen to ammonia, and measuring the quantity of ammonia present, which may then be related to the original nitrogen composition.
TITRATION CELL COULOMETER RECORD R \HYDROGENATION E *HYDROCRACKING ZONE VAPORIZING PATENTEDUET 2 6 ISTI SHEET 2 BF 2 V HYDROGENATION ZONE /HYDROCRACKING ZONE g7 Hydrogen VAPORIZING ZONE INVENTOR. lfsumi Jack Oifa A TTOR/VEY NITROGEN DETERMINATION AND APPARATUS THEREFOR BACKGROUND OF THE INVENTION My invention relates to a method and apparatus for automatic quantitative analysis. More specifically, it relates to an improved method and apparatus for analyzing the nitrogen composition of nitrogen-containing materials. In particular, my invention relates to a method and apparatus for hydrocracking nitrogen-containing organic materials, hydrogenating the nitrogen contained therein to ammonia, and measuring the ammonia present in the material from which the original nitrogen composition of the material can be determined. Coulometric titration means are particularly advantageous and convenient for the required ammonia analysis.
Rapid and accurate organic nitrogen determinations are of great importance in many processes, particularly in the petroleum industry. In certain refinery processes, especially those using platinum catalysts, the presence of nitrogen compounds have a deleterious effect on the process due to nitrogen poisoning of the catalyst. On the other hand, in other processes, the presence of certain nitrogen compounds in the process streams is necessary. An example of this is when nitrogen compound additives are blended into lubricating oils. The level of nitrogen present in process streams can range from less than a few parts per million to well over 5 percent. Furthermore, the boiling point of nitrogen-containing materials in process streams can range from about 150 F., as in naphtha, to over l,000 F. for certain oil additives. Therefore, it is difficult to have a single method and apparatus which can determine the nitrogen composition of most of the process streams found in a refinery. As a result of this, improved methods and means for nitrogen analysis of samples having widely varying properties are of great importance to those in the petroleum industry.
Essentially, most methods for the determination of nitrogen use one of three basic approaches: Kjeldahl, Dumas or ter Meulen. Modifications and improvements of these three basic approaches are many, but none have achieved the desired goals of high sensitivity and short analysis time, and can also be used in analyzing high-boiling nitrogen-containing samples. Usually, the nitrogen content of a sample can be determined by the Kjeldahl method, which employs sulfuric acid digestion and steam distillation of ammonia. This method, although being quite sensitive, requires a relatively long digestion time so that the total time required in an analysis can be from 2 to 6 hours. For many applications this lengthy analysis time is unsatisfactory. The Dumas method, involving the oxidation of nitrogen compounds over copper oxide and the subsequent reduction of the nitrogen present to elemental nitrogen, requires less time for analysis but is less sensitive. The ter Meulen method involves the catalytic production of ammonia from nitrogen-containing compounds and the subsequent measurement of the ammonia formed. This method offers the advantages of both high sensitivity and relatively short analysis times. The drawback to the ter Meulen method, up to this time, is that it has not been adaptable to the analysis of higher boiling nitrogen-containing materials.
The ter Meulen method converts nitrogen to ammonia by hydrogenation over a nickel-on-magnesia catalyst. lnvestigations show that at temperatures of from about 600 to about 750 F., the alkaline nickel-on-magnesia catalyst traps and holds acidic gases such as H 8 and HCl. Then, at temperatures above 750 F these acidic gases are slowly released and pass with the ammonia to the device used in measuring the ammonia present. The gases may then interfere with the required ammonia analysis. Since temperatures in excess of l,000 F. are often required for vaporization of certain nitrogen-containing organic materials such as heavy cycle oils, decanted oils, lubricating oils and lubricating oil additives, the nickelon-magnesia catalyst would necessarily be at a temperature at which the acidic acids are released and thus such high boiling samples cannot be analyzed using the basic ter Meulen method.
Prior art nitrogen analyzers have often had difficulty in analyzing viscous, nitrogen-containing samples because of problems encountered in introducing the sample into the analyzer. Conventional methods of introducing nitrogen-containing samples into nitrogen analyzers are by drawing the sample into a long needle syringe, introducing the needle of the syringe into a permeable septum system built into the analyzer, and injecting the sample through the needle into the analyzer. Viscous, nitrogen-containing samples will not flow easily through the relatively small bore syringe needle and, therefore, such a method often becomes impractical My invention includes a method and apparatus for eliminating this problem.
The method and apparatus of my invention are improvements over the inventions claimed and disclosed in U.S. Pat. No. 3,461,042. This patent discloses a method for nitrogen determination by the catalytic conversion of nitrogen to ammonia and the coulometric titration of the ammonia so produced. The invention of this patent requires the use of the nickel-on-magnesia ter Meulen catalyst and therefore is limited to the analysis of lower-boiling nitrogen-containing materials. My invention, however, extends the use of the apparatus and method of that patent application to the analysis of higher-boiling samples.
SUMMARY OF THE INVENTION I have found that the determination of nitrogen in nitrogencontaining materials can be improved by first hydrocracking the material, in the presence of hydrogen and a suitable hydrocracking catalyst, to lower molecular weight components and then hydrogenating the lower molecular weight components to convert the nitrogen present to ammonia. The hydrocracked products will have a lower boiling point than the original sample and can thus be hydrogenated at lower temperatures. A suitable catalyst for hydrocracking the nitrogen-containing material comprises rhodium on either a silica-alumina base, a molecular sieve base or a base comprising mixtures of silica-alumina and zeolitic molecular sieve material. Additionally, I have found that the determination of nitrogen present can be improved by passing the hydrocracked material through a bed of nickel granules immediately after passing it through the hydrocracking catalyst. It is understood that the term nickel granules is intended to include nickel shot, nickel particles, nickel turnings and other particulate forms of nickel. For best results, the hydrocracking catalyst should be at a temperature of about l,400 F. and if a bed of nickel granules is also used, this bed can also be at about 1,400 F. or somewhat lower.
In order to perform the steps of hydrocracking and hydrogenation, it is necessary to mix the vaporized nitrogencontaining sample with a carrier gas. The carrier gas acts to dilute the sample and to sweep it through the zones of hydrocracking and Although any nonnitrogen-containing inert gas may be used as the carrier, it is most advantageous to use hydrogen gas for this purpose since hydrogen is required in the hydrocracking and hydrogenation steps. Humidifying the hydrogen gas is effective in inhibiting the coking of the hydrocracking catalyst.
The apparatus for determining the nitrogen content of a nitrogen-containing material which uses the method of my invention comprises a reactor, including zones for vaporizing, hydrocracking and hydrogenating the sample and a means for analyzing the reactor effluent for nitrogen contained therein. Various means of analyzing the nitrogen are possible but one that has been found most convenient comprises an automatic coulometric titrator as described in U.S. Pat. No. 3,461,042. Means for introducing hydrogen into the reactor must be provided and preferably this means should also include provisions for humidifying and heating the hydrogen gas.
In order to solve the problem of introducing viscous nitrogen-containing material into the nitrogen analyzer without permitting the escape of carrier gas or the vaporized, nitrogen-containing material, I have found that the nitrogen material should be encapsulated in a substance which melts at a temperature no higher than the temperature encountered in the vaporizing zone of the nitrogen analyzer. The encapsulated nitrogen-containing material is then introduced into the vaporizing zone. The encapsulated material may be introduced into the analyzer through a vapor lock" zone comprising a chamber communicating alternatively with the nitrogen analyzer vaporizing zone and the exterior of the analyzer. In this manner an operator may insert the samplecontaining capsule into the chamber, interrupt the communication between the exterior of the analyzer and the chamber, and initiate communication between the chamber and the vaporizing zone of the nitrogen analyzer so that the capsule is introduced into the vaporizing zone.
BRIEF DESCRIPTION OF THE DRAWING Hg. 1 is a schematic view of the complete nitrogen determination system showing a hydrogen humidifier, a reactor, and a titration cell.
FIG 2 is an enlarged view of the reactor, partially in section, showing the vaporization, hydrocracking and hydrogenation zones, as well as an improved sample inlet means.
DESCRIPTION OF A PREFERRED EMBODIMENT Briefly, the method of my invention for automatically determining the nitrogen content of an organic material involves the steps of passing the organic material through a hydrocracking zone to crack the organic material into lower molecular weight components, converting the nitrogen in the material to ammonia by hydrogenation and determining the quantity of ammonia produced. In my method, the hydrocracking zone includes a suitable hydrocracking catalyst such as one comprising rhodium on a silica-alumina base, a molecular sieve base or on a base comprising a mixture of silica-alumina and zeolitic molecular sieve material. It has been found that a hydrocracking catalyst containing about 0.6 percent rhodium is effective. After hydrocracking the sample, the nitrogen is converted to ammonia by passing the hydrocracked material through a hydrogenation zone containing a suitable hydrogenation catalyst. One type of hydrogenation catalyst which has been found to be suitable comprises nickel on a magnesia base. Conveniently the nitrogen-containing sample is mixed with a carrier gas such as hydrogen prior to being passed through the hydrocracking and hydrogenation zones. In order to inhibit coking of the hydrocracking catalyst, humidification of the hydrogen gas carrier has proven satisfactory.
More specifically, my method comprises introducing the nitrogen-containing material into a vaporizing zone, mixing the vaporized material with humidified hydrogen, passing the vaporized material and humidified hydrogen through a hydrocracking zone at a temperature in the range of between about l,400 F. and about l,440 F., passing the vaporized hydrocracked product and humidified hydrogen through a bed of nickel granules at a temperature in the range of between about 1,400 F. and l,440 F., passing the hydrocracked material and humidified hydrogen through a hydrogenation zone at a temperature in the range of between about 680 F. and about 750 F. to convert the nitrogen present to ammonia, and coulometrically titrating the ammonia produced in the hydrogenation zone to determine the amount therein. For viscous samples, the nitrogen-containing material is conveniently introduced into the vaporizing zone by encapsulating it in a material which melts at a temperature no higher than that encountered within the vaporizing zone and introducing the encapsulated material into the vaporizing zone through a vapor lock. Less viscous samples of nitrogencontaining material can be introduced into the vaporizing zone by means of the syringe and septum technique described above.
The apparatus ofmy invention, for determining the nitrogen content of an organic material, comprises a reactor including a vaporizing zone, a hydrocracking zone, a hydrogenation zone, and an analyzing means in communication with said reactor for quantitatively detecting the presence of ammonia. The reactor provides for the passage of the nitrogen-contain ing sample sequentially through the vaporizing, hydrocracking and hydrogenation zones, and further provides for the passage of a sample to the analyzing means. The vaporizing zone includes a heating means sufficient to permit the passage of the nitrogen-containing sample into the hydrocracking zone as a vapor. Accordingly, the heating means should be capable of heating the sample to a temperature of at least about 1,400" F. The hydrocracking zone must contain a hydrocracking catalyst, such as the conventional silica-alumina base catalyst, or the newer molecular sieve-type hydrocracking catalyst. The incorporation of minor amounts of rhodium on either the silica-alumina base catalyst or the molecular sieve catalyst provides improved hydrocracking performance. About 0.6 percent rhodium has been found to be a suitable amount to incorporate in the hydrocracking catalysts of my invention. Furthermore, I have found that providing a bed of nickel granules subsequent to the hydrocracking zone improves and enhances the operation of the apparatus.
The hydrogenation zone includes a suitable hydrogenation catalyst such as is described in 24 Analytical Chemistry 1755-1756. Modifications of that particular catalyst or other hydrogenation catalysts might also be used in the hydrogenation zone of myapparatus.
The reactor should also include provisions for the introduction of a carrier gas to be mixed with the nitrogen-containing sample material prior to the hydrogenation zone, which successively sweeps the sample through the reactor and into the analyzing means. The optimum carrier gas for use in my invention is hydrogen because it is needed in the hydrocracking and hydrogenation zones of the reactor and is also used for the determination of nitrogen when using the preferred coulometric titrating apparatus. Preferably, the hydrogen carrier gas should be humidified and heated to about 200 F. before being introduced into the reactor in order to inhibit coking of the hydrocracking catalyst.
As stated previously, carrier gas leakage becomes a problem when introducing heavy, viscous nitrogen-containing samples into the apparatus. 1 have solved this probiem by providing the reactor with a novel inlet means. This inlet means includes a vapor tight chamber capable of communication alternatively with the reactor vaporizing zone and the exterior of the apparatus. An embodiment of such an inlet means comprises a substantially vertical conduit in communication with the reactor vaporizing zone. The conduit contains a plug mounted for rotation within the conduit flow passage so as to prevent the passage of material through the conduit. A well or other type of receptacle is present within the plug and adapted to receive a sample container introduced into the conduit. Due to the substantially vertical nature of the conduit, the sample container is held within the well by gravitational forces. Rotation of the plug within the conduit reorients the well from its container-receiving position to a position such that the well communicates with the reactor vaporizing zone. Again, because of the substantially vertical nature of the conduit, any sample container present within the well drops from the well and is introduced into the reactor vaporizing zone. It is evident the plug must be properly seaied within the conduit flow passage to prevent the escape of carrier gas from the reactor.
Another embodiment of the above-described inlet means comprises a substantially vertical tube having a'lower end in communication with the vaporizing zone of the reactor and an upper end adapted for receiving samples from a source outside of the reactor. The tube has mounted within it a large bore stopcock. A stopcock made of Teflon would be most suitable, although one made from Pyrex glass would also be satisfactory. The stopcock has its bore sealed at one end by the presence of a septum, preferably composed of silicone rubber. This septum prevents material from passing through the stopcock bore, but is also of such a nature that it can be pierced by a hypodermic needle and still remain substantially vapor tight once the needle is removed. Thus a sample container receptacle is formed by the walls of the stopcock bore and the septum. In using this novel inlet means, the stopcock is first turned so that the unsealed end of the bore is in communication with the upper end of the tube. A container holding the sample material, sized so as to fit completely within the container receptacle, is inserted into the tube so that it drops into the container receptacle. In order to introduce the sample container into the reactor, the stopcock is merely turned about 180. This permits the sample container to fall from the receptacle into the reactor vaporizing zone. It is essential that the sample container be composed of a material which melts at the temperature encountered within the vaporizing zone so that the sample can be vaporized, mixed with the carrier gas and passed through the reactor.
Any apparatus for ammonia determination may be used as the analyzing means of my invention. This includes, but is not limited to, colorimetric and acidimetric analyzers. However, a particularly desirable type of analyzing means which is conveniently adapted for use with my invention is the automatic coulometric titration apparatus described in U.S. Pat. No. 3,461,042. The automatic coulometric titration apparatus is particularly convenient for use with my invention, not only because of its sensitivity and rapidity of analysis, but also because the hydrogen gas required is readily available as the carrier sweep gas. Since the automatic coulometric titration apparatus and method are fully described in the above-mentioned patent applications, there is no need to repeat such a description here.
The method and apparatus of this invention may be more fully understood by referring to FIGS. 1 and 2. It is understood that in FIG. 1, all connecting lines are of% inch copper tubing unless other wise noted. A source of hydrogen gas is connected to water tank 11 of humidifier 12 via line 13 and valve 14. Bypass line 15, using valve 150 as a bypass control, is connected to line 13 ahead of valve 14 to permit the flow of dry hydrogen gas around water tank 11. Water tank 11 is wrapped with heating tape (not shown) to permit the heating of the water contained therein to a temperature of at least 200 F. Line 16 extends from the outlet of water tank 11 and connects to Swagelock joint 18. Bypass line 15 connects to outlet line 16 ahead ofhydrogen flow valve 17.
Reactor 19 consists of a is-inch O.D. quartz U-shaped tube having a sample inlet 20 attached to vertical arm 19a. Sample inlet 20 is of Pyrex glass and contains a large 8 mm. bore Pyrex stopcock 21. Sample inlet 20 is attached to reactor 19 by graded seal 22. Graded seal 22 is required in order to bond Pyrex sample inlet 20 to quartz vertical arm 19a. Reactor 19 is provided with hydrogen inlet 23 at a point somewhat below graded seal 22. Hydrogen inlet 23 connects with Swagelock joint 18 by butyl rubber tubing joint 24 and line 25. Tubing joint 24 is needed to provide sufficient flexibility to minimize breakage of hydrogen inlet 23 when connecting or disconnecting humidifier 12 from the reactor. Within reactor 19 are vaporizing zone 16, hydrocracking zone 27 and hydrogenation zone 28. Vaporizing zone 26 is in the horizontal portion of reactor 19 and is provided with a resistance wire heating means 29. Heating means 29 should be capable of providing temperatures of at least 1,030 F. within vaporizing zone 26.
Hydrocracking zone 27 and hydrogenation zone 28 are both located in vertical arm 31 of reactor 19. Hydrocracking catalyst 30 is present within hydrocracking zone 27 and comprises 0.6 percent rhodium on a silica-alumina cracking catalyst support. This catalyst is prepared by dissolving the calculated amount of rhodium chloride in the maximum amount of water (predetermined by titration) that the silicaalumina support can absorb without appearing "wet." The rhodium chloride solution and silica-alumina support are mixed, air-dried, and pelleted to 56-inch pellets. These pellets are calcined at l,020 F. for 2 hours and then ground to 16-35 mesh. Above hydrocracking catalyst 30 is a bed of reagent grade nickel granules 32, also having a size of from 16 to 35 mesh. Hydrocracking zone 27 is provided with a heating means, such as a furnace (not shown) which keeps the hydrocracking catalyst 30 and nickel granules 32 at about l,400 F. This furnace should be capable of maintaining hydrocracking catalyst 30 and nickel granules 32 at a temperature of about l,650 F.
A hydrogenation catalyst 33, comprising nickel on a magnesia base, is located in hydrogenation zone 28, which is above hydrocracking zone 27. Hydrogenation zone 28 is provided with a heating means, such as a furnace (not shown), which ordinarily keeps hydrogenation catalyst 33 at a temperature of about 680 F. This furnace should be capable of heating hydrogenation catalyst 33 to about l,100 F.
Outlet 34 of reactor 19 connects to inlet 35 of titration cell 36 via glass connection line 37. Titration cell 36 electrically connects to coulometer 38, which in turn electrically connects to recorder 39. Titration cell 36 contains a suitable electrolyte such as aqueous sodium sulfate at a pH of about 5.95. Such an electrolyte may be prepared by dissolving about 5 g. of reagent grade sodium sulfate in 1 liter of ion-exchanged water.
In using the apparatus, it is necessary to first obtain properly sized samples. I have found that best results are obtained when sample sizes are selected according to the following table:
Sample size, mg. Nitrogen Content, I:
0. l0.4 3-6 0.4-1 0.3-3 2-10 (ml-0.2
if the nitrogen-containing sample material is volatile such as naphtha or refinery waste water, a measured amount can be introduced into reactor 19 by means of a long needle syringe inserted through the silicone rubber septum 21a of stopcock 21. Any samples, but particularly viscous ones which cannot be forced through a syringe, can be encapsulated in tin sample container 40. Sample container 40 is about 5X13 mm. in size.
The apparatus and method of my invention have been used to analyze a number of different nitrogen-containing samples and the results obtained have been compared with other methods of analyses. Table 1 shows results of analyses performed with lubricating oils or base stock lubricating oils. The nitrogen content in the samples ranged from about 50 p.p.m. to over 1,000 ppm. The data presented in table 2 are the results of similar analyses on oil additives and miscellaneous oils. These samples had nitrogen contents much higher than those shown in table 1.
TABTEII Nitrogen,
Run
Sample Kjeldahl Coulometric DiltZ, Z:
Blend lube oil 0.108 0106 2.0
(Dumas) J Oil additive 6.22 6.00 3,7
(Dumas) K Oil additive 1.53 L55 [.3 L
Oil additive [.43 1.46 2.1 M
Additive package 0.56 0.55 2.0 N
Additive package 0.5 B 0.56 2.0
Aluminum rolling oil 025 0.27 3.7 P
Hydraulic fluid 0.0802 0.0800 02 Except as indicated, all comparison runs were made using the Kjeldahl method. Two comparison runs were made using the Dumas method because the compounds being tested contained nitrogen-nitrogen linkages and therefore could not be analyzed by the Kjeldahl method. All samples analyzed in tables l and ll were similar in viscosity and boiling points.
In order to test the apparatus on nitrogen-containing samples having a wide range of boiling points, analyses were performed on a series of light cycle oils, heavy cycle oils and decanted oils. Again, the Kjeldahl method was used for the purposes of comparison. Results from these analyses are presented in table lil.- Run U was used to calibrate the coulometric titration apparatus. Theoretically, calibration is not required since the amount of titrant generated can be calculated from the coulombs used in the titration. However, calibration simplifies the use of the equipment. The samples analyzed cover a boiling point range from about 250 F. to about 1,200 F. Even for the higher boiling samples, it was possible to keep the nickel-magnesia hydrogenation catalyst at about a 700 F. temperature. If hydrocracking did not take place prior to hydrogenation, the samples having boiling points in the l,000 F. range would not have been correctly analyzed.
TABLE III Analyses of LCO, l-lCO and DO The apparatus described above gives quick and accurate determinations of nitrogen content. Nitrogen values can be reported within fifteen minutes after the sample is accepted for analysis. Thus, my invention can be used both to monitor plant processes or to make quick checks of certain blending operations. The catalysts used in my invention have long life times. Over 400 analyses were carried out on a single catalyst filling. The procedure is simple, and once the equipment is set up and operating conditions have stabilized, relatively unskilled personnel can perform the actual determinations.
The foregoing description of the present invention is given for illustrative purposes only and various modifications in the apparatus and in the process itself will become apparent to the skilled worker from a reading of the description. However, such modifications are intended to fall within the scope of my invention.
Having described the invention, what I claim is:
1. In a method for automatically determining the nitrogen content of an organic material, by the steps of converting the nitrogen to ammonia by means of passing the organic material through a hydrogenation zone containing a nickel-on-magnesia catalyst and then determining the quantity of ammonia present, the improvement comprising first introducing the organic material into a vaporizing zone, mixing the vaporized organic material with hydrogen, passing the vaporized material and hydrogen through a hydrocracking zone containing a hydrocracking catalyst at a temperature sufficient to hydrocrack the organic material, and then passing the vaporized hydrocracked product to said hydrogenation zone.
2. The method of claim 1' wherein said hydrocracking catalyst comprises rhodium on a molecular sieve base.
3. The method of claim 2 wherein said hydrocracking catalyst comprises about 0.6 percent rhodium.
4. The method of claim I wherein said hydrocracking catalyst comprises rhodium on a silica-alumina base.
5. The method of claim 4 wherein said hydrocracking catalyst includes about 0.6 percent rhodium.
6. The method of claim 1 wherein said organic material is mixed with hydrogen gas prior to being passed through said hydrocracking zone.
7. The method of claim 6 wherein said hydrogen is humidified to inhibit coking of the hydrocracking catalyst.
8. A method for automatically determining the nitrogen content of an organic material comprising:
a. Passing said organic material through a vaporizing zone in the presence of humidified hydrogen, wherein said organic material is converted to a vapor phase;
b. Passing the effluent from said vaporizing zone which includes vaporizing organic material and humidified hydrogen through a hydrocracking zone, said hydrocracking zone including a hydrocracking catalyst,
at a temperature in the range of between about l,400 F.
and about l,440 F.;
c. Passing the effluent from said hydrocracking zone through a bed of nickel granules at a temperature in the range of between about l,400 F. and about l,440 F.;
d. Contacting the effluent from said bed of nickel granules with a nickel-on-magnesia catalyst at a temperature in the range of between about 680 F. and about 7 l 5 F., to convert the nitrogen in said organic material to ammonia; and
e. Coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic materi al.
9. The method of claim 8 wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base.
10. The method of claim 8 wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a silica-alumina base.
11. An apparatus for determining the nitrogen content of an organic material comprising:
a. A reactor including in series:
i. a vaporizing zone including a heating means for vaporizing said organic material;
ii. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about 1,400 F. and 1,440 F; and
iii. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680 F. and 715 F., and
b. Analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially:
c. Through said vaporizing zone to insure that said organic material is in the vapor state;
d. Through said hydrocracking zone to convert said organic material to lower molecular weight components;
e. Through aid hydrogenation zone to convert any nitrogen present to ammonia; and
wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
12. The apparatus of claim 11 wherein said supply means further includes means for humidifying said hydrogen.
13. The apparatus of claim l 2 wherein said supply means further includes a temperature control means whereby said humidified hydrogen may be supplied to the reactor at a temperature of about 200 F.
14. The apparatus of claim 11 wherein said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
15. The apparatus of claim 14 wherein said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on silica-alumina, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
16. The apparatus of claim 11 further including a hydrogen supply means in fluid communication with said reactor and adapted to supply hydrogen to said reactor at a point within said reactor prior to said hydrocracking zone.
17. A method for automatically determining the nitrogen content of an organic material comprising:
a. introducing said organic material into a vaporizing zone in the presence of humidified hydrogen by the steps of 1. encapsulating said organic material in a substance which melts at a temperature less than the temperature within the vaporizing zone; and
2. introducing the encapsulated organic material into the va orizing zone;
. passing effluent from said vaporizing zone which includes vaporized organic material and humidified hydrogen through a hydrocracking zone, said hydrocracking zone including a hydrocracking catalyst, at a temperature in the range of between about l,400 F. and about l,440 F.;
. passing effluent from said hydrocracking zone through a bed of nickel granules at a temperature in the range of between about l,400 F. and about M402 F.;
d. contacting effluent from said bed of nickel granules with a nickel-on-magnesia catalyst at a temperature in the range of between about 680 F. and about 715 F.. to convert the nitrogen in said organic material to ammonia; and
e. coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic material.
18. The method of claim 17 wherein the encapsulating material is tin.
19. An apparatus for determining the nitrogen content of an organic material comprising:
a. a reactor including in series:
I. a vaporizing zone including a heating means for vaporizing said organic material;
2. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about l,400 F. and L440 F; and 3. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680 F. and 715F.; and
b. inlet means to said reactor comprising:
1. a substantially vertical conduit having an upper end, a lower end which is in communication with said vaporizing zone, and an interior passageway along its longitudinal axis; and
2. a plug having a well, said plug being rotatably mounted within said passageway, said well being in registration with the passage of said conduit so that as said plug is rotated within said bore, the well alternatively communicates with the upper end of said conduit and the lower end of said conduit;
c. analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially:
d. through said vaporizing zone to insure that said organic material is in the vapor state;
e. through said hydrocracking zone to convert said organic material to lower molecular weight components;
fr through said hydrogenation zone to convert any nitrogen present to ammonia; and
wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
20. An apparatus for determining the nitrogen content of an organic material comprising;
a. a reactor including in series:
1. a vaporizing zone including a heating means for vaporizing said organic material;
2. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about l,400 F. and 1440 F.;
3. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680 F. and 7 l 5 F.;
b. inlet means to said reactor comprising:
1. a substantially vertical tube having an upper end and a lower end which is in communication with said vaporizing zone, and a passageway along its longitudinal axis, and a hole passing through the surface of said tube communicating with the passageway of said tube; and
2. a stopcock mounted for rotation within said hole in said tube, said stopcock at all times preventing flow through the passageway in said tube, said stopcock having a flow passage, one end of which is sealed;
c. analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially;
d. through said vaporizing zone to insure that said organic material is in the vapor state;
e. through said hydrocracking zone to convert said organic material to lower molecular weight components;
f. through said hydrogenation zone to convert any nitrogen present to ammonia; and wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
i t t i t

Claims (26)

  1. 2. The method of claim 1 wherein said hydrocracking catalyst comprises rhodium on a molecular sieve base.
  2. 2. introducing the encapsulated organic material into the vaporizing zone; b. passing effluent from said vaporizing zone which includes vaporized organic material and humidified hydrogen through a hydrocracking zone, said hydrocracking zone including a hydrocracking catalyst, at a temperature in the range of between about 1,400* F. and about 1,440* F.; c. passing effluent from said hydrocracking zone through a bed of nickel granules at a temperature in the range of between about 1,400* F. and about 14402 F.; d. contacting effluent from said bed of nickel granules with a nickel-on-magnesia catalyst at a temperature in the range of between about 680* F. and about 715* F., to convert the nitrogen in said organic material to ammonia; and e. coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic material.
  3. 2. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about 1,400F. and 1,440* F; and
  4. 2. a plug having a well, said plug being rotatably mounted within said passageway, said well being in registration with the passage of said conduit so that as said plug is rotated within said bore, the well alternatively communicates with the upper end of said conduit and the lower end of said conduit; c. analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially: d. through said vaporizing zone to insure that said organic material is in the vapor state; e. through said hydrocracking zone to convert said organic material to lower molecular weight components; f. through said hydrogenation zone to convert any nitrogen present to ammonia; and wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
  5. 2. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about 1,400* F. and 1440* F.;
  6. 2. a stopcock mounted for rotation within said hole in said tube, said stopcock at all times preventing flow through the passageway in said tube, said stopcock having a flow passage, one end of which is sealed; c. analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially; d. through said vaporizing zone to insure that said organic material is in the vapor state; e. through said hydrocracking zone to convert said organic material to lower molecular weight components; f. through said hydrogenation zone to convert any nitrogen present to ammonia; and wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
  7. 3. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680* F. and 715* F.; b. inlet means to said reactor comprising:
  8. 3. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680* F. and 715* F.; and b. inlet means to said reactor comprising:
  9. 3. The method of claim 2 wherein said hydrocracking catalyst comprises about 0.6 percent rhodium.
  10. 4. The method of claim 1 wherein said hydrocracking catalyst comprises rhodium on a silica-alumina base.
  11. 5. The method of claim 4 wherein said hydrocracking catalyst includes about 0.6 percent rhodium.
  12. 6. The method of claim 1 wherein said organic material is mixed with hydrogen gas prior to being passed through said hydrocracking zone.
  13. 7. The method of claim 6 wherein said hydrogen is humidified to inhibit coking of the hydrocracking catalyst.
  14. 8. A method for automatically determining the nitrogen content of an organic material comprising: a. Passing said organic material through a vaporizing zone in the presence of humidified hydrogen, wherein said organic material is converted to a vapor phase; b. Passing the effluent from said vaporizing zone which includes vaporizing organic material and humidified hydrogen through a hydrocracking zone, said hydrocracking zone including a hydrocracking catalyst, at a temperature in the range of between about 1,400* F. and about 1,440* F.; c. Passing the effluent from said hydrocracking zone through a bed of nickel granules at a temperature in the range of between about 1,400* F. and about 1,440* F.; d. Contacting the effluent from said bed of nickel granules with a nickel-on-magnesia catalyst at a temperature in the range of between about 680* F. and about 715* F., to convert the nitrogen in said organic material to ammonia; and e. Coulometrically titrating the ammonia produced in step (d), the amount of titrant required for said titration being a measure of the nitrogen content in said organic material.
  15. 9. The method of claim 8 wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base.
  16. 10. The method of claim 8 wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a silica-alumina base.
  17. 11. An apparatus for determining the nitrogen content of an organic material comprising: a. A reactor including in series: i. a vaporizing zone including a heating means for vaporizing said organic material; ii. a hydrocracking zone including a hydrocracking catalyst bed and means for maintaining said hydrocracking catalyst bed at a temperature between about 1,400* F. and 1,440* F; and iii. a hydrogenation zone containing a nickel-on-magnesia hydrogenation catalyst bed and means for maintaining said hydrogenation catalyst bed at a temperature between about 680* F. and 715* F.; and b. Analyzing means for quantitatively detecting the presence of ammonia, said analyzing means in fluid communication with said reactor wherein said organic material passes sequentially: c. Through said vaporizing zone to insure that said organic material is in the vapor state; d. Through said hydrocracking zone to convert said organic material to lower molecular weight components; e. Through said hydrogenation zone to convert any nitrogen present to ammonia; and wherein effluent from said hydrogenation zone is passed to said analyzing means to determine the amount of ammonia present therein.
  18. 12. The apparatus of claim 11 wherein said supply means further includes means for humidifying said hydrogen.
  19. 13. The apparatus of claim 12 wherein said supply means further includes a temperature control means whereby said humidified hydrogen may be supplied to the reactor at a temperature of about 200* F.
  20. 14. The apparatus of claim 11 wherein said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on a molecular sieve base, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
  21. 15. The apparatus of claim 14 wherein said analyzing means is a coulometric titrator, wherein said hydrocracking catalyst comprises 0.6 percent rhodium on silica-alumina, and wherein said hydrocracking zone further includes at least one bed comprising nickel granules.
  22. 16. The apparatus of claim 11 further including a hydrogen supply means in fluid communication with said reactor and adapted to supply hydrogen to said reactor at a point within said reactor prior to said hydrocracking zone.
  23. 17. A method for automatically determining the nitrogen content of an organic material comprising: a. introducing said organic material into a vaporizing zone in the presence of humidified hydrogen by the steps of
  24. 18. The method of claim 17 wherein the encapsulating material is tin.
  25. 19. An apparatus for determining the nitrogen content of an organic material comprising: a. a reactor including in series:
  26. 20. An apparatus for determining the nitrogen content of an organic material comprising; a. a reactor including in series:
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US4081345A (en) * 1975-08-04 1978-03-28 Max-Planck-Gesellschaft Zur Foerderung Der Wissenschaften E.V. Apparatus for determining small amounts of nitrogen
US4929314A (en) * 1989-07-07 1990-05-29 The Dow Chemical Company Coulometric titrator apparatus and method
WO1995000842A1 (en) * 1993-06-22 1995-01-05 The University Of Newcastle Electrochemical sensor
US5976888A (en) * 1998-12-07 1999-11-02 Biochem Technology, Inc. Method for measuring NOx in biochemical processes
US6106718A (en) * 1998-07-01 2000-08-22 Biochem Technology, Inc. Enhanced denitrification process by monitoring and controlling carbonaceous nutrient addition
US6143246A (en) * 1998-08-18 2000-11-07 Biochem Technology, Inc. Apparatus for measuring ammonia in biochemical processes
US20040225455A1 (en) * 2003-03-27 2004-11-11 Southwest Research Institute Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection
DE19741810B4 (en) * 1997-09-23 2005-09-15 Ech Elektrochemie Halle Gmbh Method for total nitrogen determination

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3964869A (en) * 1973-03-01 1976-06-22 N.K. Verwaltungs Ag Analytical apparatus for serial determination of nitrogen in samples by the Kjeldahl method
US4081345A (en) * 1975-08-04 1978-03-28 Max-Planck-Gesellschaft Zur Foerderung Der Wissenschaften E.V. Apparatus for determining small amounts of nitrogen
US4929314A (en) * 1989-07-07 1990-05-29 The Dow Chemical Company Coulometric titrator apparatus and method
WO1995000842A1 (en) * 1993-06-22 1995-01-05 The University Of Newcastle Electrochemical sensor
DE19741810B4 (en) * 1997-09-23 2005-09-15 Ech Elektrochemie Halle Gmbh Method for total nitrogen determination
US6106718A (en) * 1998-07-01 2000-08-22 Biochem Technology, Inc. Enhanced denitrification process by monitoring and controlling carbonaceous nutrient addition
US6143246A (en) * 1998-08-18 2000-11-07 Biochem Technology, Inc. Apparatus for measuring ammonia in biochemical processes
US6416652B1 (en) 1998-08-18 2002-07-09 Bio Chem Technology, Inc. Method for measuring ammonia in biochemical processes
US6248595B1 (en) 1998-12-07 2001-06-19 Biochem Technology, Inc. Method of measuring a nitrification rate for liquids
US5976888A (en) * 1998-12-07 1999-11-02 Biochem Technology, Inc. Method for measuring NOx in biochemical processes
US20040225455A1 (en) * 2003-03-27 2004-11-11 Southwest Research Institute Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection
US7189574B2 (en) * 2003-03-27 2007-03-13 Southwest Research Institute Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection
US20070117210A1 (en) * 2003-03-27 2007-05-24 Owen Thomas E Measurement Of Nitrogen Content In A Gas Mixture By Transforming The Nitrogen Into A Substance Detectable With Nondispersive Infrared Detection
US7781220B2 (en) 2003-03-27 2010-08-24 Southwest Research Institute Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

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