CA1125266A

CA1125266A - Process for the conversion of relatively low molecular weight hydrocarbons, to higher molecular weight hydrocarbons catalyst-reagents for such use in such process, and the regeneration thereof

Info

Publication number: CA1125266A
Application number: CA332,109A
Authority: CA
Inventors: Howard L. Mitchell, Iii; Robert H. Waghorne
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1979-04-05
Filing date: 1979-07-19
Publication date: 1982-06-08
Also published as: US4239658A; NO792967L

Abstract

ABSTRACT OF THE DISCLOSURE

Novel regenerable catalyst-reagents, and a new and improved process utilizing said regenerable catalyst-reagents, for the conversion, and oligomerization of hydrocarbons, notably methane, at relatively low temperatures to produce products rich in ethylene and/or benzene, and process for the regeneration of said catalyst-reagents. The catalyst-reagents are multi-functional and are comprised of (1) a Group VIII
noble metal having an atomic number of 45 or greater, nickel, or Group I-B noble metal having an atomic number of 47 or greater; (2) a Group VI-B metal oxide which is capable of being reduced to a lower oxide, or admixture of metal oxides which includes one or more of such metal oxides; and, (3) magnesium, strontium or barium, composited with a suitably passivated, spinel-coated refractory support, notably an inorganic oxide support, or calcium composited with a non-zinc containing passivated, spinel-coated refractory support, preferably alumina.

Description

1~2~6~i 1 It is the business of many refineries and chemical

2 plants to obtain, process and upgrade relatively low value

3 hydrocarbons to more valuable feeds, or chemical raw mater-

4 ials. For example, methane, the simpliest of the saturated hydrocarbons, is often available in rather large quantities 6 either as an undersirable by product in admixture with other 7 more valuable higher molecular weight hydrocarbons, or as 8 a component of an off gas from a process unit, or units.
9 Though methane is useful in some chemical reactions, e.g., as a reactant in the commercial production of methanol and 11 formaldehyde, it is not as useful a chemical raw material 12 as most of the higher molecular weight hydrocarbons. For 13 this reason process streams which contai~ methane are usually 14 burned as fuel.
Methane is also the principal component of natural 16 gas, which is composed of an admixture of normally gaseous 17 hydrocarbons ranging C4 and lighter and consists principally 18 of methane admixed with ethane, propane, butane and other 19 saturated, and some unsaturated hydrocarbons. Natural gas is produced in considerable quantities in oil and gas fields, 21 often at remote locations and in difficult terrains, e.g., 22 off-shore sites, artic si~es, swamps, deserts and the like.
23 Under such circumstances the natural gas is often flared 24 while the oil is reco~ered, or the gas is shut in, if the field is too remote for the gas to be recovered on a commer-26 cial basis. The construction of pipelines to carry the gas 27 is often not economical, due particularly to the costs of 28 connecting numerous well sites with a main line. Transport 29 of natural gas under such circumstances is also uneconomical 31 because methane at atmospheric pressure boils at -258F and ~

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,~z~2266 1 transportation economics dictate that the gas be liquefiable 2 at substantially atmospheric pressures to reduce its volume.
3 Even though natural gas contains components higher boiling 4 than methane, and such mixtures can be liquefied at somewhat higher ~emperatures than pure methane, the temperatures re-6 quired for condensation of the admixture is nonetheless too 7 low for natural gas to be liquefied and shipped economically.
8 Under these circumstances the natural gas, or methane, is 9 not even of sufficient value for use as fuel, and it is wasted.
The thought of utilizing methane from these sources, 11 particularly avoiding the tremendous and absolute waste of a 12 natural resource in this manner, has challenged many minds;
13 but has produced few solutions. It is highly desirable to 14 convert methane to hydrocarbons of higher molecular weight lS than methane (hereinafter, C2+) particularly admixtures of 16 C2 hydrocarbon products which can be economically liquified 17 at remote sites; especially admixtures of C2~ hydrocarbons 18 rich in ethylene or benzene, or both. Ethylene and benzene 19 are known to be particularly valuable chemical raw materials for use in the pet~oleum:i petrochemical, pharamaceutical, 21 plastics and heavy chemicals industries. Ethylene is thus 22 useful for the production of ethyl and ethylene compounds in-23 cluding ethyl alcohol, ethyl ethers, ethylbenzene, styrene, 24 ethylene oxide, ethylene dichloride, ethylene dibromide, ace-tic acid, polyethylene and the like. Benzene is useful in 26 the production of ethylbenzene, styrene, and numerous other 27 alkyl aromatics which are suitable as chemical and pharmaceu-28 tical intermediates, or suitable in themselves as end pro-29 ducts, e.g. as solvents or high octane gasoline components.
It is a primary objective of the present invention 31 to provide the art with novel catalysts, and a catalyst pro-32 cess for the production of higher molecular weight hydrocar-33 bons from lower molecular weight hydrocarbons, especially 34 for the production of C2+ hydrocarbons from rnethane, natural gas, process streams rich in methane, and the like.
36 A specific object is to provide novel regenerable :

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1 catalyst-reagents, and a new and improved process u~ilizing 2 said regenerable catal~st-reagents, for the conversion, and 3 oligomerization of methane at relatively low tempera-tures 4 to higher molecular weight hydrocarbons, particularly pro-ducts rich in ethylene or benzene, or both, usually in admix-6 ture with other hydrocarbons.
7 These and other objects are achieved in accordance 8 with the present invention which embodies:
9 (a) novel multi-functional regenerable catalyst-reagents which are comprised of (l) a Group VIII noble me-11 tal having an atomic number of 45 or greater, nickel, or a 12 Group I-B noble metal having an atomic number of 47 or grea-13 ter (Periodic Table of the Elements; Sargent Welch Scienti-14 fic Company, Copyright 1968), or admixture which includes one or more of said metals; (2) a Group VI-B metal oxide 16 of the Periodic Table of the Elements which is capa~le of 17 being reduced to a lower oxide, or admixture of metal oxides 18 which includes one or more of such metal oxides; and, addi-l9 tionally (3) selected from the group consisting of barium, magnesium, strontium or an admixture which includes one or 21 more of such me~als, composited with a suitably passivated, 22 spinel-coated refractory support, notably an inorganic oxide 23 support, preferably alumina; Gr calcuim, composited with a 24 suitably possivated, non-zinc containing spinel coated re-fractory support, notably an inorganic oxide support, prefer~
26 ably aluminai 27 (b) a novel hydrocarbon conversion process where-28 in a hydrocarbon feed, notably methane, or methane-containing 29 gas, is contacted with a catalyst-reagent as characterized in (a), supra, at temperature ranging from about 1150F to 31 about 1600F. preferably from about 1250F, to about 1350F
32 at sub-atmosphere, or supra atmospheric pressure sufficient to 33 react and form C2+ hydrocarbons; and 34 (c) a proces~s for regeneration of said catalyst-reagent which has become i.nactivated as by use in the pro-36 cess characterized in (b), supra, by contact thereof in an ~' .
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1 exothermic reaction wlth water, oxygen or an oxygen-contain-2 ing gas, preferably air, at temperatures sufficient to re-3 oxidize the Group vI-s metal oxide, or metal oxides, and pre-4 ferably also sufficient to provide the required sensible heat to said novel hydrocarbon conversion process (b), supra 6 on recycle of the catalyst-reagent; which suitably ranges 7 from about 100F to about 1600F, pre~erably from about 1250F
8 to about 1450F, carbon dioxide and water being released in 9 the regeneration reaction.
The novel catalyst-reagents are multi-functional 11 and, though the exact nature of the reaction paths are by no 12 means certain, the included components are believed to play 13 different mechanistic functions in the production of oligo-14 mers from the low molecular weight h~drocarbon feeds, nota-bly methane. The Group I-B (silver, gold) or VIII (rhodium, 16 palladium, osmium, iridium and platinum) noble metals, or 17 nickel, the first essential component, of which the Group VII
18 noble metals notably platinum, iridium and palladium, but par-19 ticularly platinum, are preferred, is believed to enter into a dissociative chemisorption reaction with the h~drocarbon 21 feed and cause it to lose hydrogen. For example, in the reac-22 tion with methane, the Group I-B, Group VIII noble metal, or 23 nickel, functions to cause dissociative chemisorption of the 24 methane onto the surface of the catalyst to produc e species which can react to form ethylene directly, another species `26 which reacts to form ethane and higher molecular weight ali-27 phatic hydrocarbons, or both, and other species which can 28 directly react with the Group VI-B metal oxide to form water.
29 The`Group VI-B metal oxide, the second essential component, is characterized as an oxide which is capable of 31 being reduced in the reaction to a lower oxide or the zero 32 valent metal, or both. The reducible Group VI-B metal oxide 33 component, comprising an oxidej or oxides, of the multivalent -34 metals chromium, molybdenum and tungsten, is believed to pro-vide a catalytic function, in addition to the reagent function 36 which is a function of the change o oxidation state of the 37 metal. Thus, it acts as a reagent in that it is ~, ~ , .

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1 believed to donate o~ygen for reaction with abstracted hydro-2 gen to ~orm water and thereby provide the energy necessary to 3 sustain the reaction. In its catalytic function, it is be-4 lieved that the low valence oxides of the Group VI-B metal, or the completely reduced metal, provide a cyclization func-

6 tion whereby acetylene, acetylldes and the like, and perhaps

7 even ethylene are converted into aromatics, notably benzene.

8 Thus, it is one or more of the products of the reagent func-

9 tion of the Group VI-B metal oxide components which are be-lieved to provide the catalytic function of the G~oup VI-B
11 metals.
12 It has also been found that the activity of the 13 Group VI~s reducible metal oxide to react with abstracted 14 hydrogen and form water can be supplemented, or enhanced, by the additional presence of oxides of (i) 5roup III-A
16 metals having an atomic number of 31 or greater (gallium, 17 indium and thallium), (ii) ~roup IV-B transition metals of 18 atomic number ranging from 22 to-40 (titanium and zirconium), 19 5iii) Group V-B transition metals (vanadium, niobium and tan-talum), ~iv) Group VII-B transition metals (manganese and 21 rhenium), (v) Group VIII non-noble metals of atomic number 22 ranging from 26 to 27 ~iron and cobalt), (vi) metals of the 23 lanthanum series of atomic number ranging from 58 to 71 (cer-24 ium, praseodymium, neodynium, samarium, europium, gad~linium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, 26 lutetium), and (vii) metals of the actinum series of atomic 27 number ranging from 90 to 92 (thorium and uranium. Of these, 28 the preferred oxygen donor compounds comprise the oxides of 29 vanadium, noibium, rhenium, cerium and uranium.
The Group II-A metals (magnesium, calcium, stron-31 tium and barium,) of which barium is highly preferred, con-32 stitute the third ~ssential component of the catalyst. The - 33 Group II-A metal is put on the catalyst support as an oxide 34 and, in performing its function, is believed to form a Group '!
II-A metal carbide, or carbides as intermediates during the 36 course of the reaction. This, of course, does not suggest :.

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~hat other species containing the Group II-A metal are not formed, and possibly active during the reaction. However, in an i~itial stage it is believed that the oxide of the Group II-A metal supplies oxygen which reacts with abstrac~ed hydrogen to form water, thus providing some of the energy for the reaction.
Barium particularly as barium peroxide (BaO2) ab initio, is believed to function particularly well in this aspect. The Group II-A metal carbides, particularly carbides of the heavier Group II-A metals, are also believed to orm compouncls which possess carbon-carbon bonds, or polycarbon-carbides which are through to be intermediates, or precursors of intermediates, in the formation of cyclic compounds. While most of these polycarbon-carbides are believed to be C2 species, bari~m, in particular is believed to form some C3 species, making barium especially preferred ~or generation of cyclic hydrocarbons by the present process.
It is also essential in the formation of these catalysts that the several components be composited with a passivated surface, spinel-coated inorganic metal oxide support, preferably a spinel-coated alumina upon which the several components are sequentially impregnated, or co-impregnated by any of the common techniques in use for the preparation of heterogeneous catalysts.
The term "spinel", as used herein, designates a binary oxide which is characterized as having either a normal or inverse spinel structure. The normal spinel structur~ can be represented by the formula MY2O4 wherein M and Y are cations of dif~erent metals, and the inverse spinel structure can be represented by the formula Y (XY~O4 wherein Y and X are cations of different metals. The sum of the cationic charges o~ a spinel, whether normal or inverse, is equal to 8. A description of the spinel-type structures is found in Structural Inorganic Chemist~y, A. Fo Wells, 3rd Edition, Oxfoxd, the Clarendon Press, 1962, at pages 487-488.
While calcium is the preferred Group II-A reagent metal it is nonetheless essential that calcium reagent not be , -, .

1 employed in the presence of æinc. This is true even when 2 the zinc ls present as a constituent or part of the passi-3 vated, spinel-coated surface, e.g., as when the calcium is 4 depsoited on a zinc aluminate spinel carrier, or zinc alu-minate spinel coated support. The presence of zinc, among 6 other things, causes the formation of considerable amounts 7 o~ coke with drastic reduction i~ the formation of the de-8 sired products.
9 Thermodynamic considerations of the possible reac-tion paths leave little doubt but that numerous possible re-11 action paths favor the formation of a considerable amount 12 of coke and/or carbon dioxide, with little or no yield of 13 potentially valuable products, a conclusion which fits well 14 with the results of many past experiments. However, pursuant lS to the practice of this invention, albeit some coke, poly-16 meric, or carbonaceous meterial is produced, essentially all 17 of this material that is formed in the reaction is burned 18 to carbon dioxide and fully utilized in the regeneration 19 stage to provide process heat. On the other side of the pro-cess, relatively little carbon dioxide is formed in the reac-21 tions taking place in the main reactor. It has been demon-22 strated that the catalyst-reagents of this invention, under 23 the desired conditions for conducting the process, produce 24 products containing an admixture of valuable oligomers, particularly ethylene and benzene.
26 Though the exact nature of the reaction paths is 27 by no means certain, as suggested, it is believed that the 28 Group I-B noble metaIs and Group VIII noble metals, inclusive 29 of nickel, function to cause one or more dissociative chemi-sorptions of the methane onto the surface of the catalyst to 31 produce species which may react to form ethylene directly, or 32 another species which may react to form ethance and higher 33 molecular weight aliphatic hydrocarbons, or both, and another 34 species such as adsorbed hydrogen, which may react directly with the transition metal or other oxide to form water. Or 36 such species may react with the Group II-~ carbides to . .
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-,', 1 liberate ethylene, form acetylene, or other products, form 2 intermediates which lead to cyclization, or react with cy-3 clization or polymerization products to form benzene or 4 other products which appear in the exit gases from the reac-tor. The Group VI-s metal oxide also may react directly with 6 abstracted or liberated hydrogen to form water, and by inter-7 action with a Group I-s noble metal or Group VIII noble metal, 8 or nickel, is believed to form water and a species which fur-9 ther reacts to form ethylene. Where methane is used as a feed, it is thus envisioned that the reaction mechanisms with 11 a multivalent Group I-B noble metal or Group VIII noble metal, 12 or nickel, referred to as "M", may include the following se-13 quences of reactions, to wit:
14 ~CH3 ~1) M l CH4 ~ M~ ~ MH ~ ~CH3 16 (2) 2MCH~ ~ 2M + H3C-CH3 17 (3) MCH3 + ~1 ~ M=CH2 + MH
18 (4)2M=CH2 ~~ 2M ~ H2C-CH2 19 and, 21 (5)M + C2H6 ~ M

23 It is also envisioned that the multivalent transition metal 24 oxide, M'On, the transition metal being designated as M', the oxygen atoms associated with ~', or the ratio o~ oxygen atoms 26 to M atoms in the association since n need not be an integer, 27 reacts with the intermediate MH [Equation (1), supra] as 28 follows:
29 (6) 2MH + M~On ~ M + M~On 1 + H20 and with abstracted and liberated hydrogen as follows;
31 (7) M'On ~ H2 ~~ M n-l ' H20 32 and, M' participates with M in reacting with methane, as follows:

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1 (8) M'On + CH4 + M ; M'On l + H20 + ~=C~2 2 Likewise, I'n_l and M n-l can further react in similar man-3 ner to produce additional water, ethylene, ethane, and other 4 hydrocarbons until ~he valence of M, M' and M" have been re-duced to some lower level or to zero, at which time further 6 reactions such as described are no longer possible without 7 reoxidation of the catalyst by regeneration.
8 The presence of the Group II-A metal component, 9 favors the production of larger amounts of benzene in the pro-ducts of the reaction. In this type of reaction, i-t is be-11 lieved that the methane or organometallic intermediates inter-12 act with the Group II-A metal component to form metal carbides 13 and water. The carbides, acetylides, propadiynides and the 1~ like, it is believed, react in turn with the water or ab-stracted or liberated hydrogen to generate benzene, ethylene, 16 and/or the other products of the process.
17 It is known that acetylene can be trimerized at cer-18 tain conditions to yield benzene, but it is also known that 19 free acetylene also has a propensity to react to form coke;
which form of reacting is high undesirable. Such reaction 21 can thus be represented by the following equation, to wit:
22 (9) C2 2 --~ Heat ~ (C2)x ~ ~2 ( or Coke + H2) 23 In the catalytic reaction of this invention, howe~er, it is 24 not believed that free acetylene is formed and whereinafter C2H2 is represented in the equation, the acetylene is believed 26 present only as a transient, or molecular species complexed 27 with one or more metal atoms, and which is rapidly converted 28 into benzene, ethylene or other hydrocarbon or coke. There-29 fore, it is theorized that the reaction pathway to the forma-tion of benzene may be shown by equations 10-16, infra. Re-31 presenting a Group II-A metalsas M", and a carbide, acetylide, 32 or the like of such metals as M"mC, ~"mC2, M"mC3, the designa-33 tions denoting the degree of association of carbon/carbide 34 anions within the material, all of which generally fit in the "metal carbide" category, and the subscripts denoting generally 36 the number of metal atoms associated with e~ch carbide anion ` .
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1 carbon or group of carbons, the following reactions are be-2 lieved to occur in forming the carbides, ~cetylides, to wit:
3 (10) ~M"0 + CH4 ~ M 2C + _H20 4 (11) M"02 + CH4 ~ M"C + 2H20 (12) M"2C, M"C, etc. ~ M"C2, M"C~, M"2C~, etc.
6 The acetylene forming reaction i5 representiny by the follow-7 ing equation, to wit:
8 (13) M"C2 ~ H2O ~~ M~0 + C2H2 9 The ace~ylene ~rl~eri~a~ion m.a~ be represented by the follow-ing equation:
11 (14) 3C2H2 ~ Catalyst ~ C6H6 + Catalyst 12 ,~here the catalyst is M' or lower valent `I'Oz and a similar 13 sort of dimerization of C3 materials is likewise possible.
14 An alternate more likely cyclization route can also take place directly from the carbide, to wit:
16 ~15) ;M"C2 ~ M'02 ~ 2M"0 l M'C6, etc.
17 (16) M'C6 + 6MH ~ .6M + ~1l C6H6 18 (17) 2M"C3 ~ M'02 -~ 2M"0 M'C6 19 (18) M'C6 + 6CH4 ~ 6M ~ M' + 6MCH3 ~ C6H6 2Q Another alternate pathway ~or the cyclization to 21 benzene involves the dehydrogenation and cyclization of three 22 ethylenes via reactions on the M and M' catalyst and reagent 23 metals.
24 ~owever, it is also possible that the reaction path-way to C2 hydrocarbons, inclusive of ethylene and benzene may 26 be through.the catalytic or thermal formation of a particular 27 type of "coke" which catalytically or thermally decomposes in 28 the reaction to form the thermally stable volatile products, 29 benzene and ethylene, to wit:
(19) CH4 + Catalyst ~ "Coke" + Catalyst + H~0 31 (20) "Coke" ~ Catalyst (+2CH4) ~ Coke + C2H41 C6H6 32 The catalyst or feed, or both~, may be urnishing hydrogen to : ,~ -:

1 decompose the ''Coke" as, to wit:
2 (21) ~5 + CH4 ~ ~ + "Coke"
3 ~22) MH ~ "Coke" ~ M ~ C2H4 + C6H6 4 In the preparation of the catalyst-reagents, a por-ous metal oxide support, preferably one which has been desur 6 faced by contact with steam, i5 first passivated and the sur-7 face thereof converted to a spinel. This is accomplished by 3 treatment of the support with at least one metal component, 9 (other than zinc when calcium is to be deposited on the sup-port), preferably a Group II-A metal, such that the sum of 11 the ionic charges of the metal of the metal oxide support and 12 the metallic element, or metallic elements, of the metal com-13 ponent used to treat the support satisfy the requirement for 14 spinel formation, i.e., that the sum of the valences equals 8 and the ionic radii of the metals satisfy the requirements 16 for formation of the normal or inverse spinel type structures.
17 Exemplary of materials which can be used as supports are mag-18 nesium oxide, titanium oxide, zirconium oxide, hafnium oxide, 19 and the like, preferably alumina. Suitably, the metal oxide support, preferably one having an initial surface area ranging 21 from about 50 m2/g to about 250 m2/g, preferably about 150 m2/
22 g, is treated by contact, and impregnation with a solution of 23 a compound of the desired me~al component which is deposited 24 on the metal oxide support. The treated or impregnated metal oxide is subsequently calcined, suitably a~ a temperature rang-26 ing from about 925F to about 1825F, this producing a surface 27 spinel or spinel-coating on the metal oxide support. The spi-28 nel surfaced support is then treated with a solution, or solu-29 tions, containing compounds which provide the essential sub-stitutents characterized in (a), supra.
31 The~several components are deposited on the passi-32 vated spinel-coated support by the impregnation method. Pur-33 suant` to this method, a compound, or compounds which contain 34 the desire~ metal, or metals, are dissolved in solution in the desired concentration. The support in solvated, dry or .

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1 calcined state is contacted with the metal or metals-contain-2 ing solution, or solutions, and thereby impregnated by either 3 the so-called "incipient wetness" technique, or technique em-4 bodying adsorbtion from a dilute solution, or solutions, with subsequent drying of the support. In the impregnation pro-6 cedure, the Group II A metal is generally first impregnated 7 onto the passivated, spinel-coated support; the amount added 8 to the support being additional to any such similar or dis-9 similar metal which may have been used to form the spinel-coating, since that used in forming the spinel is not con-11 tained thereon in active form. The Group II~A metal impreg-12 nated support is then, preferably, calcined in an inert or 13 oxidizing atmosphere and the Group VI-R metal is then impreg-14 nated onto the support, and again calcined. Suitably also, compounds of the Group II-A and VI-B metals can be coimpreg-16 nated onto the passivated, spinel-coated surface and the sup-17 port then dried and calcined. It is essential, in either 18 event, after deposition of the Group VI-B metal to calcine the 19 catalyst-reagent in an oxidizing atmosphere, i.e., in the pre-sence of air or an oxygen-containing gas, to convert the 21 Group VI-B metal to an oxide. The Group III-A, and transition 22 metals of IV-B, V-B, VII-B, inclusive also of the lanthanide 23 and actinium series metals, and iron and cobalt, alone or in 24 admixture with other metals are similarly imprengated onto the support and the impregnated support calcined in an oxidizing 26 atmosphere to form an oxide, or oxides of the metal. The 27 Group I-B or Group VIII noble metal, or nickel, is generally 28 impregnated onto the passivated, spinel-coated support after 29 depsoition of the other essential components and then calcined, suitably in nitrogen, or added by compregnakion with one or 31 more of the other essential or non-essential components.
32 Where the impregnating compound contains halogen, or other un-33 desirable component, wet calcination may be employed to remove 34 the halide from the catalyst-reagent. In all embodiments, the support can be treated by contact with a single solution con-36 taining the desired amounts of a metal, or metals, or treated 1 sequentially by contact with a solution containing one metal, 2 and then with a solution which contains another metal, or me-3 tals, in the desired amounts. Large particles, whether pilled, 4 pelleted, beaded or extruded, can be so-treated and then crushed to the desired size, or the particle can be pre-re-6 duced in size, and then treated. The catalyst-reagent, in 7 either instance, can then be dried, calcined and then con-8 tacted as fixed, fluidized or moving bed with the feed at the 9 desired reaction conditions.
In the preparation of ~he catalyst-reagents the Group 11 I-B or Group VIII noble metals, or nickel, is deposited on the 12 support in concentration ranging from abou~ 0.01 percent to 13 about 2 percent, preferably from about 0.1 to about 1 percent, 14 calculated as metallic metal based on the weight of the tokal catalyst-reagent (dry basis). The reducable Group VI-B metal 16 oxide is deposited on the catalyst-reagent in concentration 17 sufficient to supply at least one-half of an atom of oxygen 18 for each hydrocarbon molecule which is to be oligomerized, 19 and preferably at least one atom of oxygen for each hydrocar-bon which is to be oligomerized. Generally, at least about 21 1.1:1 to at Ieast 1.5:1 atoms of oxygen are supplied for each 22 molecule of methane when high ethylene content is desired in 23 the product. At least 1.5:1 atoms of oxygen are supplied 24 for each molecule of methane when high benzene content is desired in the product. The Group VI-B metal is deposited on 26 the catalyst-reagent in concentration ranging from about 1 per-27 cent to about 20 percent, preferably from about 3 percent to 28 about 10 percent, calculated as metallic metal based on the 29 weight of the total catalyst-reagent (dry~basis). Suitably also the oxldes of the Group III-A metals, the oxides of the 31 Group IV-B, V-B, VII~ transitional metals, the oxides of iron, 32 cobalt and the oxides of the metals of the lanthanide and ac-33 tinide series are deposited on the catalyst in concentration 34 ranging from about 0.01 percent to about 25 percent, prefera-bly from about 5 percent to about 15 percent calculated as 36 metallic metal based on the weight of the total catalyst-,, , , . . , - . : '' ' ' ~, . . . .

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1 reagent (dry basis). The oxide of the Group II-A, or alka-2 line earth metal is deposited on the catalyst-reagent in con-3 centration ranging from about 1 percent to about 30 percent, 4 preferably from about 5 percent to about 25 percent calcula-ted as metallic metal based on the weight of the total ca-6 talyst-reagent (dry basis). In compositing these metals with 7 the catalyst-reagent, the Group II-A metal is composited in 8 an amount sufficient to provide an atomic ratio of at least 9 about 3:1 relative to the Group VI-B metal, and preferably the ratio of the Group II metal/Group VI-B metal ranges from 11 about 3:1 to about 40:1, preferably from about 5:1 to about 12 12:1 when a relatively high concentration of benzene is de-13 sired in the product.
14 The catalyst-reagent~ particularly in view of its dual role as reagent and catalyst, eventually loses its acti-16 vity and its activity must be restored. Restoration of the 17 activity o~ the catalyst-reagent is performed by oxidative 18 regeneration, i.e., by contact of the catalyst-reagent with 19 water, oxygen or oxygen-containing gas, perferably air, at temperatures sufficiently elevated to burn off accumulated 21 coke and reoxidize the Group VI-B metals and Group II-A me-~2 tals; as well as the metals of Groups ~ A,IV-B, V-B, VII-~, 23 iron, cobalt and the lanthanides and actinides, to the extent 24 they are present in the catalyst-reagent. Temperatures on the order of about 700F are generally adequate to reoxidize 26 these metals and restore the activity of the catalyst-reagent, 27 but preferably temperatures on the order of about 1000F to 28 about 1600F, more preferably from about 1250F to about 29 1450F, are employed in the regeneration zone and the hot regenerated catalyst-reagent is recycled to the hydrocarbon 31 reaction zone in quantity sufficient to supply the sensible 32 heat needed for the reaction. Generally, adequate heat is 33 maintained by burning the coke from the catalyst-reagent 34 during the regeneration~ Pressure, while not critical, is generally maintained above atmospheric, suitably between 36 atmospheric and about 20 atmospheres.

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. : , , - , : , - 15 ~ 66 1 The invention will be more fully understood by re-2 ference to the following non-limiting examples which illus-3 trate its more salient features. All parts are in terms of 4 weight except as otherwise specified.

6 A catalyst-reagent, Catalyst A, was prepared from 7 a MgA12O4 spinel blocked alumina support made by impregnating 8 via the incipient wetness technique a commercially available, 9 high purity gamma alumina calcined at 1000F for two hours to produce an alumina having a surface area of 193 m /g (B.E.T.) 11 with an aqueous solution of magnesium nitrate. The magnesium 12 solution was added to the support in amount calculated to de-13 posit 2.9 percent Mg onto the support. The impregnated sup-14 port was dried, and then subjected to a subsequent calcination at 1000F for four hours, and at 1300F for an additional hour.
16 The MgA12O4 spinel blocked alumina support was then impregna-17 ted with an aqueous barium nitrate solution and calcined for 18 4 hours at 1000F. The barium nitrate impregnation was also 19 via the incipient wetness technique with subsequent calcina-tion, alternate impregnations and calcinations having been 21 conducted nine times in sequence to bring the barium concentra-22 tion up to 6.9 percent. After the final calcination, a chro-23 mium nitrate solution was then impregnated onto the catalyst-24 reagent to provide chromium concentration of 5.0 percent after calcination for 4 hours at 1000F wi~h subsequent calcination 26 in air at 1300F for 1 hour. The calcined catalyst-reagent 27 was then impregnated by adsorption from dilute solution with 28 a hexchloroplatinic acid, H2PtC14, solution sufficient to 29 provide 0.3 weight percent platinum on the catalyst-reagent, and again calcined for 16 hours in air at 1300F.

__ 32 A 5 gram portion of Catalyst-reagent A was charged 33 into a quartz tube furnace and heated slowly at essentially 34 ambient pressure with a flowing stream of nitrogen over a per-iod of 6 hrs. to 1300F. The flow of nitrogen was then dis-36 continued, and then a stream of essentially pure methane 37 ~99.4~) was passed across the catalyst-reagent for 30 :

.
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1 minutes. The flow of methane was then discontinued and ni-2 trogen was again introduced, the nitrogen having been sub-3 stituted at the end of this period to act as a carrier gas.
4 The entire effluent was collected in a neoprene rubber bag during the time that hydrocarbons were evlolved from the 6 system. A sample of the collected product was then subjected 7 to a mass spectrometric gas analysis. The following Table I
8 shows the hydrocarbon components present in the gaseous pro-9 duct ln significant quantity.
Table I
11 ComE~onent Mol Percent Weight Percent 12 CH4 55.480 39.441 13 C2H4 4 . 000 4 . 983 14 C2H6 1.634 2.178 C4H~ 0.014 0.028 16 n~C4Hlo -0.901 0.002 17 C6H6 2.367 8.192 18 The coke on the catalyst was me~sured at 1.04 wt.
19 %, approximately 44.8 mole percent of the methane haYing been converted with a maximum of 19.3 mole percent of the methane 21 having formed coke; for a significant amount of the coke is 22 carbides which are capable of further conversion. Approxi-23 mately 25.4 mole percent of the methane was converted to C2+
24 product, 8 mole percent of the methane having formed ethylene, 3.26 mole percent of the methane having formed ethane, and 26 14.4 percent of the methane having formed benzene.

28 An additional series of catalysts, prepared as ln 29 Example 1, but with the impregnation of other essential metal-lic or metal oxide components, or other blocking agent for 31 preparation of the spinel; and these catalysts employed in a 32 series of runs at conditions similar to that described in Ex-33 ample 2. The results obtained are tabulated in Table II.

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1 EX~PLE 4 2 Catalyst-reagents were prepared from spinel blocked 3 alumina supports made by impregnating via the incipient wet-4 ness technique a commercially available, high purity gamma alumina calcined at 1000F for two hours to produce an alumina 6 having a surface area of 193 m2/g (B.E.T.) with an aqueous 7 solution of a salt of the blocking metal. For example, in the 8 preparation of a CaA12O4 spinel blocked alumina support, a 9 calcium nitrate solution was formed by dissolving calcium ni-trate in water, and the calcium solution was then added to the 11 support in amount calculated to deposit 3.5 percent Ca onto 12 the support. The impreganted support was dried, and then sub-13 jected to a subsequent calcination at 1000F for four hours, 14 and at 1300F for an additional hour. The CaA12O4 spinel blocked alumina support was then impregnated with an aqueous 16 solution of a salt of the desired Group II-~ metal, e.g., cal-17 cium nitrate, as in the preparation of Catalyst F, and calcined 18 for 4 hours at 1000F. Impregnation was also via the incipient 19 wetness technique with subsequent calcination, alternate im-pregnations and calcinations having been conducted a number 21 of times insequence to bring the Group II-A metal concentra-22 tion to the desired concentration. After the final calcination, 23 a Group VI-B metal, Cr was deposited from a solution of a 24 salt of the Group VI-B metal onto the catalyst-reagent to pro-vide the desired Group VI-B metal conecntration after calcina-26 tion for 4 hours at 1000F with subsequent calcination in air 27 at 1300F for 1 hour. The calcined catalyst-reagent was then 28 impregnated by adsorption from dilute solution with an acid 2g salt of the Group VIII noble metal, e.g., a hexachloropla-tinic acid, H2PtC14, solution sufficient to provide the de-31 sired concentration of platinum on the catalyst-reagent, and 32 again calcined for 16 hours in air at 1300F.
33 A 5 gram portion of each catalyst was charged into 34 a quartz tube furnace and heated slowly at es~entially ambient pressure with a flowing stream of nitrogen over a period of 36 6 hrs. to 1300F. The flow of nitrogen was then discontinued ` ~:

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1 and then a stream of essentially pure methane (99.4~) was 2 passed across the catalyst-reagent for 30 minutes. The flow 3 of methane was then discontinued and nitrogen was again intro-4 duced the nitrogen having been substituted at the end of this period to act as a carrier gas. The entire effluent was col-6 lected in a neoprene rubber bag during the time that hydro-7 carbons were evolved from the system. A sample of the col-8 lected product was then subjected to a mass spectrometric 9 gas analysis to determine the hydrocarbon quantity, and the amount of coke deposited on the catalyst was measured.
11 The results obtained are given in Table III below.

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l TAB'.' III
2 rCSTlNG OF CATALYST REAGr.~TS rOP~ M'THANE PO~YMER~7AT10~' 3 Test ~un .~u~ber 7 8 9 10 4 Ca:alvst Designation c F ~2 G
S No~inal Catalyst Type CaCrPt CaCsPt CaCrPt (2) Ca,~IoVP~ (1) 6 Use Originaltl) Original(1) Re3enera;ed Orisinal 7 Base ~aterial M""' ~n y-A1203 r-Al,03 y-Al23 y-A~o6 8 Blocking ~Ietal Ir"' ~n Ca(;; Ca~) Ca(;~
9 Concentration Blockina ~e~al ;.7 i.; ;.S 3.4 lo ~r~ (Wt. 'i) ll ~Ietal ~I Pt P: Pt Pt 12 Concentration ~ t. ';~ 0.2 0.2 0.2 O.i l; Me:al M' Cs Cr Cr ~o l; Concentration ~ t. 'i) ;.8 3.8 3.8 7.0 lS Metal ~' Ca Ca Ca Ca 16 Concen:ratiOn M" (Wt. ~) 8.i 8.3 8.; 9.2 17 ~Ie:al M"' 18 Concontra;ion M"' (~'t. ~) o.o 0.0 0.0 10.2 19 Product Analysis Co~uonent (~ole ~;) 21 CH4 6;.. '4 ;9.93 46.20 44.7., 2' C.H, 23 C2~4 0.03 2.;3 2.~7 ;.6~
24 C,H6 0.16 0.36 0.46 0.19 2i C~H6 -- _- _ 0.O~26 C-~, -- 0.01 -- o.oo 27 C4~8 O.oo., __ 0.01 0.00 28 n~C4Hlo 0.01 -- - 0Ø 0.0129 C6H6 0.00 2.11 2.46 1.9 ;0 ~2 36.5; ;S.'l 47.98 49.;7 31 Product Conposition 32 Cosr,onent (h~
3j C~ 49.61 26.3~ 31.23 30.;4 C H -- -- -- 0.0;
;3 C2H4 0.04 2.69 ;.39 4.32 ;6 C,H6 0.24 0.47 0.;8 0.24 ;7 C,H6 -- -- -- O. 04 38 C_H8 0.02 -- 0.00 39 C4H8 0.01 -- 0.02 0.01 n-C4Hlo 0.0; __ 0.05 0.02 41 C6H6 6.E7 8.10 6.57 42 ~2 50.07 63.60 So.6i i6.
4; Coke on Catalyst (Wt. %)(4) 28.73 2.48 2.16 1.7' 4~ Coke on Catalyst Aftes 45 Regeneration (Wt. ~)(6) 0.24 O.ll 0.'2 0.16 46 (1) Orisinal eatalysts used in firs; cycle of methane polymeri~ætion.
47 (2) F~ Catalyst F once rogenerated, used in ~he second eyele of nethane pol~eri:ation.
48 (;) Coneentration of bloc~ing reagent ~etal M"" used for spinel fosr~ation is not includet as psr. of ~,~
49 concentration even though the iden~ical metal ~as used for bo;h our w ses.
(4) "Coke on Ca:alys~" cay also include significant o~uan~ities o' netal carbioe "ca.bon."
Sl (S) Testing at l atu. pressure, pure CH4 feed, ~ purge before and after, 0.; hrs~run except firs; cycle or.
52 8 above at 4.0 hss.
; (6) Regencration by f~nal 700~C air burning.

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1 From these data it will be observed that catalysts 2 which contain the Group II~A metal catalyst component, ex-3 cept where zinc is present (Test Run Number 7), are quite 4 effective in oligomerizing methane to produce product com-positions rich in ethylene and benzene. Where zinc is pre-6 sent, however, a major amount of the methane s converted to 7 coke, with minimal production of C2+ gases.
8 It is apparent that various modifications and 9 changes can be made without departing the splrit and scope of the invention.

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:

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A multi-functional regenerable catalyst-reagent composition suitable for the oligomerization of hydrocarbons which comprises (1) a Group VIII noble metal having an atomic number of 45 or greater, nickel, or a Group I-B noble metal having an atomic number of 47 or greater, (2) a Group VI-B
metal oxide which is capable of being reduced to a lower oxide, and (3) a Group II-A metal selected from the group con-sisting of barium, magnesium, strontium and an admixture which includes one or more such metals, composited with a spinel-coated refractory support, or calcium composited with a non-zinc containing spinel-coated refractory support.

2. The composition of claim 1 wherein the Group VIII
noble metal is platinum, iridium or palladium.

3. The composition of claim 1 or claim 2 wherein the Group VI-B metal is chromium, molybdenum or tungsten.

4. The composition of claim 2 wherein the spinel-coated inorganic oxide is alumina.

5, The composition of any one of claims 1, 2 and 4 wherein the said Group VIII noble metal or said Group I-B
metal is present in a concentration ranging from about 0.01 percent to about 2 percent, the said Group VI-B metal oxide is present in a concentration ranging from about 1 percent to about 20 percent and said Group II-A metal is present in a concentration ranging from about 1 percent to about 30 percent, said concentrations being calculated as metallic metal based on the total weight of the composition.

6. The composition of any one of claims 1, 2 and 4 wherein the said Group II-A metal is present in an atomic ratio of at least about 3:1 relative to the said Group VI-B
metal.

7. The composition of any one of claims 1, 2 and 4 wherein the catalyst-reagent composition contains additionally a Group III-A metal having an atomic number of 31 or greater, a IV-B, V-B or VII-B transition metal, iron, cobalt, or a metal of the actinide or lanthanide series.

8. A process for the oligomerization of a hydrocarbon feed, preferably containing methane, which comprises contacting said hydrocarbon feed with a catalyst-reagent comprising (1) a Group VIII noble metal having an atomic number of 45 or greater, nickel, or a Group I-B noble metal having an atomic number of 47 or greater, (2) a Group VI-B metal oxide which is capable of being reduced to a lower oxide, and (3) a Group II-A metal selected from the group con-sisting of barium, magnesium, strontium, and an admixture which includes one or more such metals composited with a spinel-coated refractory support, or calcium composited with a non-zinc containing spinel-coated refractory support, at temperatures ranging from about 1150°F to about 1600°F.

9. The process of claim 8 wherein the Group VIII
noble metal is platinum, the Group VI-B metal is chromium, molybdenum or tungsten, the Group II-A metal is barium, and the support is alumina.