US2388100A - Production of terpenes - Google Patents

Description

Oct. 30, 1945. E. F. WADLEY 2,338,100

PRODUCTION OF TERPENES Filed Dec. 15, 1943 Fraction boiling Sulfuric below 85F. A Id l l so '4 Chemical Treating Gas 7 l3 Oil Catalytic 20 Cracking ll :2.

Fraction boiling above 250 F. Gasoline l Tarpon! 2' Fraction Allcycl c Fraction 34 SBHIOI 25 Alkoll 33 Acid Sludge 6" JYNV ENTOR.

v ATTORNEY.

Patented Oct. 30, 1945 Application December 13, 1943, Serial No. 514,012

" UNITED. STATE 4 Claims. (Cl. 260-6755) I The present invention is directed to a method for produclng'terpene type hydrocarbons; More particularly, it is concerned with a process which includes a combination of catalytic cracking and treating steps whereby alicyclics and terpene hydrocarbons are obtained in substantial quantities.

The presence of terpene hydrocarbons in petroleum fractions has long been suspected by numerous investigators, but none of them has ever demonstrated satisfactorily that these hydrocarbons are actually present in natural petroleum.

The presence of terpene hydrocarbons in thermally cracked products has likewise been suspected and efforts have been made to segregate the terpene compounds. However, all of the early investigations reported in the literature have met with little success. It has never been demonstrated to any satisfaction whether the suspected presence of these terpene hydrocabons was due to the effect of thermal conditions on the petroleum fraction or whether it was due to the subsequent treatment with chemicals suchas sulfuric acid and alkaline reagents. In eneral, the literature is uncertain as to the actualpresence or formation of terpene hydrocarbons in petroleum distillates.

These terpene hyrdocarbons are found occurring naturally in substantial quantities in the conifers and a large industry has sprung up to recover and exploit these naturally occurring compounds of vegetable origin.

I have now discovered that a substantial quan-,

tity of terpene hydrocarbons may be produced and recovered from a catalytically cracked naphtha. This discovery is of paramount importance since it makes available large quantities of terpene hydrocarbons whichheretofore were only obtained from the conifers. spe ifically the pines, at the expense of tedious labor and destruction of the pine forests.

I have found that these terpene hydrocarbons may be obtained by subjecting a paraflinic or naphthenic gas oil to conditions of catalytic cracking whereby gasoline and heavier hydrocarbons are produced. The light gasoline fraction boiling below about 25011. is 'then subjected to treatment with a chemical reagent such as by treatment with a strong mineral acid, specifically sulfuric acid, followed by distillation to recover a fraction rich in the terpenes.

In general, my invention comprises a series of processing operations from which a product containing the terpene hydrocarbons is obtained.

I This series of processing operations-includes a .7 catalytic cracking step under carefully controlled 5 carbons. It is also desirable to segregate a: fracpene-rich fraction. V

In the catalytic cracking step, specifically 0.

conditions, a distillation step to segregate a relatively narrow boiling range fraction, a chemical treating step such as with strong sulfuric :acid, and a final distillation step to recover the ter-.

catalytic cracking operation employing the fluid catalyst technique, in which the catalyst flows through the reactor system with the hydrocarbons and is regenerated and reused, it is preferred to employ asynthetic catalyst of the 81H! mina-silica gel type at a temperature of about 950 F. and a pressure of about 5 pounds per square inch; the use of low pressure cracking is recommended for this process since the type oleflns resulting in the 85-250 F. fraction are readily converted to terpenes by chemical treat- 'ment. The catalytic cracking step may include In the treating step 'of the present invention it i is preferred to use strong sulfuric acid as the treating reagent. The amount of sulfuric acid employed to contact the catalytically cracked' naphtha is important, since, if sufficient amounts of acid are not used, the terpene hydrocarbons will not be formed. Generally, the amount of acid will vary between 5 and 15% by weight based on the catalytically cracked fraction treated. The amount of acid should not be less than the minimum figure given, but larger quantities than the maximum figure may be employed,

under some circumstances.

The' acid treatment is usually conducted at atmospheric temperatures, for example 70 F., but if desired higher temperatures, as, in the range of to F., may be used. After the acidtreatment has been completed. a sludge is separated from the treated. naphtha and either may be reused again or discarded depending on its condition. The treated naphtha isneutralized by treatment with an, alkaline reagent and then distilled under conditions of temperature and pressure to segregate a fraction boilingup to about 300 F. which'may be used as, an aviation gasoline and a fraction boiling between about 300 and 370 F. whichcontains the terpene hydrotion boiling between about 370 and 500 I".- which is also rich in alicyclic hydrocarbons.

The terpene fraction obtained in accordance with the present invention has many valuable uses.- For example, terpenes may be considered to be derivatives of isoprene which is believed to be the building block of natural rubber. Therefore, the terpene-rich fraction segregated I as described may be employed in the production for high quality drying oils. The purified terpenev hydrocarbons from the terpene fraction may be used to produce synthetic flavors, ..deodorants,

inhalants, disinfectants and may be used in many other ways' too numerous to mention. The terpene-rich fraction may be subjected to further chemical action to produce alcohols, aldehyde's and ketones. In short, this fraction may be the starting material for numerous syntheses.

The invention will befur-ther illustrated by reference to the drawing in which the single figure is a flow diagram of a preferred embodiment of my invention. In the drawing the catalytic cracking and chemical treating steps are intended to include all auxiliary separating or setrtling operations usually associated with catalytic cracking and chemical treating.

Referring now to the drawing, numeral ll designates a line through which a gas oil, preferably a naphthenic gas oil, is introduced into catalytic cracking stage l2. In catalytic cracking stage I2 suitable conditions for conversion of the gas oil to gasoline in substantial quantities are provided. These conditions have been mentioned before but may include a synthetic type of alumina-silica gel catalyst, temperatures in the range between 900 and 1000 F. and low pressures of the order of 50 pounds or less, preferably; about pounds.

-After separation of the catalytically cracked product from the catalyst in catalytic cracking stage I 2, the hydrocarbons discharge therefrom through line [3' andare injected into distillation zone I4. It is understood that distillation zone l4 may include one or more fractionation towers.

' In the present instance distillation zone it is shown as one fractionation tower. Distillation zone I4 is provided with line l5 for removal of material boiling below about 85 F., line It for segregation of a fraction boiling between about 85 and 250 F. and line I! for withdrawal of heavier constituents which may either be recracked or further treated as desired. Distillation zone I4 is also provided with heating means I8, by which temperature and pressure conditions The side stream withdrawn from distillation zone l4 through line It is discharged into chemical treating zone i9. Within this treating zone. the fraction is contacted with a chemical reagent, such as strong sulfuric acid, which is added to the treating zone by means of inlet 30. The conditions obtaining inchemical treating zone I!) have been described previously herein and further reference to the specific treating operation is not necessary. Sufiice to say that the narrow boiling naphtha fraction is intimately contacted with the sulfuric acid under time and temperature conditions such that the desired result is obtained.

are adjusted to obtain the desired fractionation.

The mixture of catalytically cracked naphtha and sulfuric acid is withdrawn from chemical treating zone l9 by way of line 20 and introduced into a separating means, such as a settling 3 'vessel 3|, where it is allowed to separate under the influence of gravity into a naphtha fraction and an acid sludge fraction. The acid sludge may be removed from vessel 3| by means of outlet 32 controlled by valve 33, and the naphtha fraction is removed from vessel 3| by means of line 34 and introduced thereby into a second distillation zone 2|. Similar to distillation zone l4, distillation zone 2| may include several fractionation towers as desired. In the present instance, however, distillation zone 2l is shown as a single'fractionating tower provided with line 22 for removal of gasoline hydrocarbons, line 23 for-segregation-of the terpene-rich fraction, line 24 for segregation of an alicyclic fraction boiling between about 270 and 500 F.,. and line 25 for discharge of heavier material and alkaline reagent which is introduced into line 34 by opening valve 26 in line 21. The object of introducing alkaline reagent into line 34 is to neutralize any residual acidity in the treated catalytically cracked naphtha fraction and to prevent decomposition of any esters remaining in the treated fraction un- .der the conditions obtaining in distillation zone 2|.

U Connected to line 24 is line 28 controlled by valve 29. Line 28 connects with line H and allows recycling of the alicyclic fraction to catalytic cracking stage l2 whereby this fraction is subjected to catalytic cracking conditions to form 35 additional amounts of gasoline and terpene-rich Q for obtaining the purified terpene hydrocarbons.

The reason for the unexpected result of the present invention in obtaining a terpene-rich fraction is not completely understood. However, it is believed that the catalytic cracking under the conditions mentioned results in the formation of compounds which, on treatment with proper chemical reagents, undergo various chemical re-- actions such as alkylation, polymerization, isomerization and cyclization such that hydrocarbons of considerably higher boiling point and molecular weight than those originally present in the cracked naphtha fraction are obtained. It is possible that all four of the several types of reactions mentioned occur in chemical treatin zone IQ of the present invention. The catalytic cracking operation is one of the essential features of the present invention. Thermal cracking is not equivalent to catalytic cracking in carrying out my improved process. Furthermore, the amount of chemical reagent such as sulfuric acid employed in chemical zone i9 should not be below an irreducible minimum, which figure will necessarily be determined by experimentation since the amount of chemical reagent required in chemical treating zone l9 will necessarily vary with the chemical reagent employed. While no less than'5% .by weight of chemical reagent should be employed when strong sulfuric acid is the treating reagent either larger or smaller amounts than this may be used when other treating reagents such as hydrogen fluoride, boron trifiuoride, aluminum chloride, or. phosphoric 'acid are substituted for the sulfuric'acid.

The boiling range ofthe catalyticallycracked naphtha subjected to' the chemical treatment in n isalsoimportantf in general, the fraction subiected to chemical treatment will includethe hydrocarbons having 8 carbon atomsin the molecule and those boiling up to about 250 1''. Preferably, however, the flnal boiling point of the fraction treated in accordance with my invention not exoeed about 215 F.

for best results.

As an important by-product of the presentinvention attention is 'directed to the fraction withdrawn from secondary distillation zone 2| 1!! line 24. This fraction boils between about 8'10 and 500 1''. and contains appreciable amounts of alicyclic hydrocarbons which in themselves may be utilized inmany syntheses; or as shown 15 in the preferred embodiment of my invention,

this fraction may be recycled to catalytic crack in'g none I! for .i'urther conversioninto gasoline or terpene-rich fractions.

The present invention will further illustrated by the following run. A catalytically cracked naphtha fraction boiling between 85 and 215' I". produced by cracking a naphthenic 8 oil in the presence of a'sy'nthetic alumina-silica J 1 catalyst at 950 1'. and pounds per square inch pressure was acid treated with pounds of strong sulfuric acid per barrel of naphtha fraction. The acid treated oil was-neutralized and rerun over a naphthenic soap obtained by ininducing caustic into the rerun still in which lubricating oil was being processed. A fraction boiling between 85 and 330 1'. was taken overhead from the distillation of the acid treated cracked naphtha and the heavier material was introduced into a vacuum still and distilled under '28 inches 0! vacuum. The fraction boiling between 840 and 370 1". was found to contain substsntial quantities oflimonene which has the structuralformula V cm inden of the polymer with limonene and turpentine as follows:

'Tcble lur 2.1.

can 1.4m cam cam-cases Lieu-rials As a further indication that products obtained in accordance with the present invention belonged to the terpene series. d y hydrogen chloride was bubbled through a terpene oil, produced as de- 5 scribed, to obtain a precipitate. Theprecipitate was removed from the unreacted material and dried and on examination was found'to have a decided odor of camphor, indicating the formation of pinene hydrochloride which is artificial camphor.-

The t'erpene-rich oil produced in accordance with the invention was also found to be insoluble inwater and soluble in alcohol which. is characteristic of the terpenes.

tion having been fully described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. A process for producing synthetic turpentine which comprises catalytically cracking a petroleurnvgas oil under temperature conditions of 900 to 1000' F. and at pressures below about 50 pounds per square inch' in the presence. of a synthetic alumina-silica gel catalyst, separating from the productsof the catalytic cracking a fraction boiling between 85 and 215 F... treating the segregated fraction with 5 to 15% by weight of strong sulfuric acid and distilling the chemically treated product to obtain a gasoline fraction, a terpene rich fraction, and a heavier I alicyclic fraction.

2. A process in accordance with, claim 1 in which the heavier alicyclic fraction is recycled to the catalytic cracking step. i

.85 3. A process for producing terp'ene-type hy'-' drocarbons which comprises the steps of subjecting a petroleum distillate boiling in the gas-oil boiling range to catalytic cracking in the presence of an alumina-silica gel catalyst, separating 40 a fraction boiling above 3 about 85 F. and no higher than 250' F. from the catalytically cracked product, chemically treating said fraction with no less than 5% by weight of strongsulfuric acid and recovering from the chemically'treated fraction a product rich in terpenes.

4. A process for producing terpene-type drocarbons which comprises the steps of subjecting a petroleum distillate boiling in the gasoil boiling range to catalytic cracking in the presence of an alumina-silica gel catalyst, separating a fraction boiling above about 85 F. and no higher than 250 1''. from the catalytically cracked product, chemically treating said.iraction with from 5 to 15% by weight or strong sulfuric acid and recovering from the chemically treated fraction a product ricli'in terpenes.

' nnwmn mans WADLEY,

The nature and objects of the presentinven-

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