NL9320046A - Hydroalkylation of aromatic hydrocarbons. - Google Patents

Description

Hydroalkylation of aromatic hydrocarbons

The invention provides a new route for the production of specification grade fine chemicals and aircraft and diesel fuel from highly aromatic materials, for example, liquids obtained from hydrogenation processes of coal or petroleum reformers. It is also known that aromatic constituents are present in liquids from the pyrolysis of coal, some shell oils and in liquids obtained from the conversion of oxygenates and hydrocarbons over zeolite catalysts.

Aromatics, because of their high octane rating, are considered excellent fuel components, however they are considered too "smoky" for commercial jet fuel and give a low cetane rating for diesel fuels. Furthermore, the emission of aromatics into unburnt and burnt fuel is an important environmental aspect, with recent and declared government legislation regarding the reduction of the aromatics content of gasoline and diesel fuels. So the saturation of the aromatics fraction or the development of alternative processing strategies, such as its hydroalkylation to non-condensed cycloalkanes, which are suitable distillate mixtures, provides a real option for refineries to cater to existing and proposed legislative and environmental pressure to decrease the aromatics content in transport fuels.

The hydroalkylation of aromatics over dual functional catalysts has previously been demonstrated and examples are to be considered incorporated herein. Slaugh, L.H. and Leonard, J.A., in U.S. Patent 3-412,165, have produced cyclohexylbenzene from benzene over a variety of transition metal catalysts, including nickel / tungsten, palladium, and platinum on zeolite and alumina supports.

Extensive research regarding the hydroalkylation of benzene has been reported by Crone, J.M. and Suggit, R.M. et al., in U.S. Patents 3-760,018, 3-760,019, 3-839-477, 3-784,617, 3-837-477, 3,869,523, and 3-926,842. The use of nickel / tungsten and cobalt / tungsten catalyst systems, along with some rare earth metals, has been investigated.

Murtha, T.P., and collaborators have extensively investigated hydroalkylation catalysts. Their work is described in U.S. Patents 4,094,918, 4,093,671, 4,094,920, 4,122,125, 4,118,434, 4,152. 362, 4,219,689. 4,268,699 βη 4,329 · 531 · Aromatic hydrocarbons, under hydroalkylation conditions and in the presence of hydrogen, were contacted with a catalyst consisting of a platinum compound or other Group VIII precious metal supported on a nickel and rare earth metal treated crystalline zeolite, which had been calcined to provide an acidic carrier.

Finally, Makkee, M., in European Patent No. 3,338,734, describes a reductive alkylation process (hydroalkylation), in which a monocycloalkyl-aromatic hydrocarbon or a substituted mono-cycloalkyl-aromatic hydrocarbon is prepared in the presence of a catalyst containing ruthenium and nickel supported on beta zeolite includes contacting an aromatic hydrocarbon or an alkyl-substituted aromatic hydrocarbon with hydrogen, respectively. The catalyst may optionally also comprise a rare earth metal or tungsten. The hydroalkylation takes place via the partial hydrogenation of the aromatic hydrocarbon to a cycloalkene. Then, the cycloolefin reacts with the aromatic hydrocarbon or the alkyl-substituted aromatic hydrocarbon to give the desired monocycloalkyl-aromatic hydrocarbon or substituted monocycloalkyl-aromatic hydrocarbon.

In a first aspect, the present invention provides a catalyst for the hydroalkylation of an aromatic hydrocarbon, the catalyst comprising a molecular sieve material with an acid function, a hydrogenation component, and a shape-selecting function, the molecular sieve material has a pore size that can accommodate molecules of the products to be produced and excludes molecules of reactants that are too large.

In a second aspect, the present invention provides a method for the hydroalkylation of an aromatic hydrocarbon, the method comprising contacting an aromatic hydrocarbon in the presence of the catalyst.

The specific limitations on the size of different molecular sieve framework structures limit the reactants and the size of product molecules through product selectivity and active site selectivity. The controlling function is the diffusion rate of product from the x-active sites, through the pores and from the crystal. Reactant selectivity is based on the exclusion of a potential reactant by its size and pore size. The shape of the product is controlled by the volume available at the active site, thereby precluding the formation of oversized intermediates at that site.

The term "molecular sieve" includes all materials which, regardless of the composition or the degree of crystallinity, exhibit shape selectivity.

The molecular sieve characteristic of the material exists where the framework structure forms a regular porous arrangement of openings. The openings are of such a size that they are able to incorporate molecules into their porous structure, while others are retained on the basis of their larger effective molecular dimensions.

Although zeolites are considered the primary molecular sieves [zeolites are crystalline aluminosilicates which are three-dimensional structures arising from a framework of coordinated [SiOi,] 4 'and [Δ10 /,] 5', which are polyedrically bonded to their angular atoms] and of great interest in the invention, other non-aluminum silicate materials, such as some carbon and silicon compounds, have molecular sieve properties. In addition, an increasing number of crystalline porous substances are synthesized, which contain a polyhedral coordination of elements other than only silicon or aluminum. Candidate elements for such an isomorphic replacement are, for example, Ga and B, near Al in group III of the periodic table of the elements, and Ge, near Si in group IV.

Other compounds based on the [PO4] 3 bonding - polyhedral coordination are known. Typical examples are the "AlPOZ)" substances prepared by the research laboratories of the Union Carbide Corporation. These are crystalline, have three-dimensional structures, are porous and are classified as molecular sieves. The total charge of the framework of pure AIPO4 is neutral, they have no ion-exchange properties, and their catalytic activity is limited. However, other similar compounds, referred to as SAPOs, have structures of Si, Al and P in tetrahedral frameworks, have a negative charge and thus ion exchange properties. Furthermore, the compounds also include MeAPOs (Me = metal), framework structures incorporating some metals from groups III, IV, V, VI, VII and VIII of the periodic table of the elements. Studies have shown that some of these materials have high catalytic activity.

Also of interest are the large number of molecularly constructed layer structures (MELs) and the columnar clay interlayers (PILC), which fill the pore site and the activity gap between the zeolites and the larger-pore amorphous gel catalysts. These are large surface solids with unique structures that have large pores that are more useful for forming the multi-ring aromatic or naphthenic molecules that are too large for conventional small pore zeolites. Materials have been developed for high thermal, reaction and regeneration stability, with new catalytic activity provided by the charged species in the intermediate layer in, for example, layered metal hydroxides or by the pillar-shaped cations that form the layers of plate minerals or clays, such as Montmorillo , smectite and hectorite, push open. The molecular sieve sorption properties of these materials and their diversity in composition makes this a versatile group of possible catalysts.

Molecular sieves with an ion exchange capacity have an increased ability to control the pore size because the exchange of ions may increase or decrease the pore size to dimensions comparable to the size of the reactant molecules and / or of the possible product. Furthermore, ion exchanges can be used to place cations at specific framework sites to form active sites that attract reactant molecules, thus promoting bond deformation and breakage, essential for molecular rearrangements. Another feature of ion exchange is that it provides a pathway for the introduction of metal cations, which can then be reduced to catalytically active metal particles. This introduces a bifunctional nature to the molecular sieves.

Molecular sieves obtain their acid or catalytic activity from the proton associated with the aluminum of the framework. This Bronsted acid site results from the formation of "hydroxyls" in the pore structure, which are usually formed by ammonium exchange followed by a calcination step. In zeolites with a high silicon content, these "protonated" species can be formed by direct exchange with inorganic acids. In this form, the hydroxyls are protons associated with negatively charged oxygen of the framework, which are bonded with alumina tetrahedra to form the Bronsted sites. These protons, especially at temperatures above 200 ° C, have great mobility and at 550 ° C they lose water, forming Lewis acid sites. The

Lewis sites, in turn, are unstable, especially in the presence of water vapor, and a tempering process occurs with the removal of Al from the framework, which becomes more stable (dealuminating).

The size exclusion and the steric inhibition, together with the intermolecular forces between the molecular sieve components and the sorbate molecules, provide opportunities for unique selectivity based on competitive sorption properties of different molecular sieves. Variables such as the ratio of silica to alumina, the nature of the cation species and the geometry of the channels (one-dimensional, multi-dimensional or supercaged interconnected) are important considerations for the catalyst. These also contribute to the stability of the catalyst, reduce its tendency to coke and increase its regeneration ability.

In the present invention, the process feed or raw material for conversion to fine chemicals and / or products or mixtures with a boiling point in the range of aviation or diesel fuel consists of an aromatic or aromatic compound containing hydrocarbon, preferably benzene and / or an alkyl-substituted aromatic hydrocarbon. The alkyl substituent may contain less than 10, preferably 1 to 5, carbon atoms. The most preferred alkyl substituent is methyl. The aromatic core can contain one or more alkyl and / or aromatic substituents. Examples of suitable starting materials include benzene, toluene, ethylbenzene, the xylenes, trimethylbenzenes, tetramethylbenzenes, biphenyl and alkyl-substituted biphenyls or mixtures thereof.

The starting mixture may contain an aromatics or a mixture of aromatics, in any other liquid or gas mixture comprising from 0 to 95 volume percent of the feed stream. The mass space velocity per hour (MHSV) of the aromatic feed can vary between 0.1 and 100 hours 1, preferably between 1 and 50 hours 1.

In the aromatic hydroalkylation process, the feed can be added to the catalyst in a reactor under a wide range of conditions. It is preferred that hydrogen be present at pressures between 1 and 200 atmospheres, more preferably between 1 and 100 atmospheres. Furthermore, the feed rate of hydrogen is preferably in a range from 0.2 to 5 moles of hydrogen per mole of aromatic feed, and more preferably between 0.2 to 1.5 moles / mole of aromatic feed.

The reaction temperature is not particularly critical, however, it preferably ranges from 80 ° C to 350 ° C.

The hydroalkylation process can be carried out in a fixed bed reactor, wherein the aromatic feed and hydrogen contact the catalyst in an upflow and downflow manner. It is also possible to use countercurrent of hydrogen and an aromatic feed over the catalyst. Although a fixed bed reactor has been described, any other type of reactor, for example, a fluidized bed reactor, a stirred phase slurry reactor, etc. may be used.

The invention provides a catalyst comprising a molecular sieve support having a pore or channel structure of sufficient size for entering reactants and leaving products and an active site selective for aromatic hydroalkylation products. The molecular sieve preferably contains what is called a medium to large pore size formed by the framework structure. The pores or channels of the molecular sieve structure should be greater than 5 Å and should preferably be of a 2-dimensional and more preferably of a 3 dimension dimensional nature and preferably interconnected. The molecular sieve support may be selected from the group of the aluminum silicate zeolites consisting of beta zeolite, Nu-2, EU-1, ZSM-4, ZSM-5, ZSM-5 / ZSM-11, ZSM- 12, ZSM-20, ZSM-23, ZSM-35. ZSM-38, ZSM-47, ZSM-48, ZSM-50, Type X, Type Y, EMC-2, CSZ-1, ECR-30, Mordenite, Offretite, Zeolite-L, Omega Zeolite and Zeolite-PHI. It may also be selected from any metal-substituted zeolite, with a portion of the aluminum and / or silicon or all aluminum and / or silicon of the previous zeolites replaced by one or more elements from groups II through VIII of the periodic table of the elements, for example Ga, B, Fe, Cr, Mn, V, Ti, Ge, As, Be, etc. The molecular sieve support may be selected from the aluminum phosphates (AlPO3s), silicon aluminum phosphates (SAPOs), metal aluminum phosphates (MeAPOs), in particular VPI-5, AlPO-5, SAP0-5, SAP0-11, SAPO-31, SAPO-36, SAPO-37, SAP0-40, SAP0-41, CoAPO-50, and other metal-substituted materials with a similar structure, e.g. BeGeAPO-11 and AsBeAP0-31. etc.

The molecular sieve used in the method of this invention may, in the form thus synthesized, comprise exchangeable cat ions, such as lithium, sodium, potassium, cesium, rubidium, beryllium, calcium, magnesium, strontium, barium, etc. . These cations can be partially or completely replaced by other cations. Particular preference is given to rare earth ions, transition metal ions (or mixtures of these ions) and other ions such as hydrogen and ammonium. The basic structure of the molecular sieve support should not change by the replacement of the initial ions, and preferably the amount of ions exchanged on the sieve is as much as can be achieved. The rare earth metal may be selected from the group consisting of cerium, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and mixtures thereof.

A preferred aspect of the molecular sieve is that it has an acid function obtained by ion exchange and / or impregnation with ammonium nitrate, ammonium fluoride, ammonium chloride, etc., followed by calcination in air at a temperature between 200 ° C and 800 ° C.

The molecular sieve can be used as prepared either after air calcination or after calcination and / or ion exchange treatment, impregnation and / or initial wetting techniques with inorganic and / or organic, metal or ammonium containing compounds. In the treatment of the molecular sieve, aqueous and / or non-aqueous solutions can be used. The preferred catalyst of this invention contains, after treatment, an active metal or active metals of group lb, lib, Mb, VIb, Vllb and VIII of the periodic table of the elements, in amounts from 0.1 wt% to 25% by weight of the catalyst. Most preferred are those elements which impart a hydrogenation component to the support. Usually it includes one or more metals selected from copper, chromium, cobalt, nickel, tungsten, molybdenum and zinc.

The catalyst may contain an additional elements or additional elements of groups V, VI, VII and VIII of the Periodic Table of the Elements which may serve as a promoter. The promoter or promoters can be added by ion exchange, impregnation and / or precipitation from aqueous and / or non-aqueous solutions of inorganic or organic compounds. Furthermore, the promoter may also be added by dry mixing a simple decomposing compound such as an acetate, nitrate, chloride, bromide, carbonyl compound, sulfide, etc. The promoter may be 0.001 wt% to 10 wt% of the catalyst. Preferred promoters are silver, copper, platinum, palladium, ruthenium, rhenium, iridium or rhodium or mixtures thereof.

The catalyst containing the metal compounds can be activated by reduction. This reduction can be carried out for 5 minutes to 2 hours in an atmosphere of 3% to 100% hydrogen, at a temperature of 50 ° C to 600 ° C and at a pressure of 0 to 200 atmospheres.

The molecular sieve can be combined, dispersed, or alternatively intimately mixed and pressed with an inorganic oxide matrix, in ratios resulting in a product containing from 10 wt% to 100 wt% catalyst in the final product. Matrices that impart desirable properties, such as increased strength and abrasion resistance of the catalyst, to the catalyst and which aid in the dissipation of the heat of reaction are preferred. Oxides of silicon, aluminum, zircon, titanium, chrome, etc. can be used. The present invention provides a catalyst and a process for the hydroalkylation of aromatics.

In a preferred form of the invention, there is provided a catalyst comprising copper, nickel and a rare earth element, which are supported on a molecular sieve having a medium to large interconnected 3-dimensional channel structure. The preferred molecular sieve may be Type X, Type Y, ZSM-20 or beta zeolite zeolite, or a combination thereof. The copper content of the catalyst can range from 2 to 25 weight percent of the catalyst, the nickel content from 1 to 25 weight percent, and the rare earth elements from 0.2 to 15 weight percent.

The active metals can be stimulated by an additional element or elements that further increase the activity, selectivity, stability and / or regenerability of the catalyst. The preferred promoter is platinum or ruthenium, and the content can range from 0.001 to 2 wt% of the catalyst.

The process of the present invention can be used to hydroalkylate aromatic compounds that boil in the gasoline range, to obtain compounds that boil in the jet and / or diesel fuel range. This increases the jet and diesel fuel fraction of a hydrocarbon stream and provides a process for reducing the benzene and total aromatics content of gasoline. The US "Clean Air Act" of November 15, 1990 requires that benzene in gasoline be limited to 1 vol. #, While the total aromatics content should be less than 25 vol. #.

The process of the present invention can be used to hydroalkylate a substantially pure compound to obtain a more valuable product or a fine chemical, for example, benzene can be hydroalkylated to cyclohexylbenzene.

In the process, any hydroalkylated product or compounds from the hydroalkylation reactor can be further purified after separation of the unreacted feed. The feed can be recycled, while the product can be further treated to a fully saturated product by adding it with hydrogen to a hydrogenation unit operated under conditions and with a catalyst known in the industry. For example, the hydroxyalkylated product of benzene, cyclohexylbenzene, can be further hydrogenated to bicyclohexyl. Purified product can be sold as fine chemicals, while less purified product can be used as a product or mixture boiling in the range of jet or diesel fuel.

To illustrate the invention, the following are included. The examples are not to be construed as limiting the scope of the invention.

Example I

The following amounts of material were put together, stirred well and sealed in a stainless steel autoclave. Sodium aluminate 12.5 g Tetraethylammonium hydroxide (40%) 263 g Ludox * HS (40% Si02) 521 g Water 188 g

The autoclave was heated to 150 ° C with stirring and kept at that temperature for 6 days. The crystalline material obtained was identified as beta zeolite (XRD, US Patent 3 * 308,069) and after washing twice with water and calcining overnight at 600 ° C, it had a chemical composition of 2.4% Al2 O3, 97.2% SiO2 and 0.01% Na2O.

40 g of the beta zeolite were ion exchanged with ammonium nitrate three times and then exchanged with a solution of nickel and a rare earth metal (1 liter containing 29.1 g Ni (NO 3) 2.6H 2 O and 0.5 g misch metal dissolved in acid. The zeolite was collected, washed, dried and then impregnated with 11.8 g copper acetate, 12.4 g nickel nitrate and 0.1 g ruthenium chloride dissolved in 200 g water. The mixture was stirred until a firm paste had formed and then dried overnight at 140 ° C, calcined at 550 ° C, pressed, milled and processed to a fraction of -500 + 250 µm.

Example 2 287 g of type Y zeolite (Strem), which has been exchanged with a rare earth metal, was further exchanged with nickel nitrate. This was dried, calcined at 550 ° C and then added to a 1000 ml solution containing 79.16 g copper acetate, 83.2 g nickel nitrate and 0.7 g ruthenium chloride. The mixture was heated and stirred until a paste had formed, dried at 140 ° C, calcined at 550 ° C, pressed, milled and processed to a fraction of -500 + 250 µm.

The catalysts described above were used in hydroalkylation tests of aromatic compounds in a pressure-fixed bed falling film reactor. The aromatics used in Test 3 were obtained from a reformate. The operating conditions as well as the results are shown in the table. The tests indicate that the support molecular sieve with the ruthenium-stimulated copper, nickel and rare earth active metals is an active catalyst for the hydroalkylation of aromatic feeds to higher boiling compounds suitable for distillation feeds or, if purified, for fine chemicals.

Hydroalkylation tests

CH = cyclohexane BCH = bicyclohexyl CHB = cyclohexylbenzene

Claims (32)

A catalyst for the hydroalkylation of an aromatic hydrocarbon, the catalyst comprising a molecular sieve material having an acid function, a hydrogenation component and a shape-selective function, the molecular sieve material having a pore size that allows molecules of accommodate the products to be produced and exclude molecules of reactants that are too large. Catalyst according to claim 1, wherein the hydrogenation component comprises an active metal or active metals selected from groups Ib, Ilb, Illb, VIb, Vllb and VIII of the Periodic Table of the Elements. Catalyst according to claim 2, wherein the hydrogenation component is selected from the group consisting of copper, chromium, cobalt, nickel, tungsten, molybdenum and zinc. Catalyst according to claim 3, wherein the hydrogenation component is copper, chromium, zinc or copper and nickel. Catalyst according to claim 4, wherein the hydrogenation component comprises copper and nickel. The catalyst of any one of claims 1 to 5, wherein the hydrogenation component comprises 0.1% to 25% by weight of the catalyst. Catalyst according to any one of the preceding claims, wherein the molecular sieve material is selected from a group of aluminum silicate zeolites consisting of beta zeolite, Nu-2, EU-1, ZSM-4, ZSM-5, ZSM -5 / ZSM-11, ZSM-12, ZSM-20, ZSM-23, ZSM-35, ZSM-38, ZSM-47, ZSM-48, ZSM-50, Type X, Type Y, EMC-2, CSZ -1, ECR-30, mordenite, offretite, zeolite-L, omega-zeolite and zeolite-PHI. Catalyst according to any one of the preceding claims, wherein the catalyst has pores with a size greater than 5 Å. Catalyst according to any one of the preceding claims, wherein exchangeable cations in the molecular sieve material are at least partially replaced by rare earth metal ions. Catalyst according to claim 9, wherein the rare earth metal is selected from the group consisting of cerium, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and mixtures thereof. Catalyst according to any one of the preceding claims, wherein the acid function is obtained by ion exchange and / or impregnation with a suitable ammonium salt, followed by calcination in air at a temperature in the range of 200 ° C to 800 ° C. The catalyst of claim 11, wherein the ammonium salt is ammonium fluoride. Catalyst according to any one of the preceding claims, wherein the catalyst contains a suitable promoter selected from an element of groups V, VI, VII and VIII of the periodic table. l. Catalyst according to claim 13, wherein the promoter comprises 0.001% to 10% by weight of the catalyst. A catalyst according to claim 13 or claim 14, wherein the promoter is selected from the group consisting of silver, copper, platinum, palladium, ruthenium, rhenium, iridium, rhodium and mixtures thereof. The catalyst of claim 15, wherein the promoter is ruthenium or platinum. A catalyst for hydroalkylating an aromatic hydrocarbon, the catalyst comprising copper, nickel and a rare earth element supported on a molecular sieve material having a medium to large interconnected 3 "dimensional channel structure. The catalyst of claim 17, wherein the molecular sieve material is selected from the group consisting of Type X, Type Y, ZSM-20, beta zeolite zeolite and combinations thereof. Catalyst according to claim 17 or claim 18, wherein copper comprises 2 to 25% by weight of the catalyst, nickel 1 to 25% by weight. $ of the catalyst and the rare earth element comprises 0.2 to 15% by weight of the catalyst. Catalyst according to any one of claims 17 to 19. wherein the catalyst contains 0.001 to 2% by weight of promoter based on the weight of the catalyst. The catalyst of claim 20, wherein the promoter is ruthenium or platinum. A process for the hydroalkylation of an aromatic hydrocarbon, the process comprising contacting an aromatic hydrocarbon with hydrogen in the presence of a catalyst according to any preceding claim. The method of claim 22, wherein the aromatic carbon comprises hydrogen benzene. The method of claim 22 or claim 23, wherein the aromatic hydrocarbon comprises an alkyl-substituted aromatic hydrocarbon. The method of claim 24, wherein the alkyl substituent comprises less than 10 carbon atoms. The method of claim 25, wherein the alkyl substituent comprises 1 to 5 carbon atoms. The method of claim 26, wherein the alkyl substituent is a methyl group. The method of claim 22, wherein the aromatic hydrocarbon is selected from the group consisting of benzene, toluene, ethylbenzene, a xylene, a trimethylbenzene, a tetramethylbenzene, biphenyl, an alkyl-substituted biphenyl, and mixtures thereof. A process according to any one of claims 22 to 28, wherein the process contacts a stream of aromatic hydrocarbons, at a mass rate per hour in the range of 0.2 to 100 hours, with hydrogen, at presence of the catalyst. The method of claim 29, wherein the hourly mass rate is in the range of 1 to 50 hours "1. The method of any one of claims 22 to 30, wherein hydrogen is present at a pressure in the range of 1 to 200 atmospheres. A process according to any one of claims 22 to 31 * wherein hydrogen is supplied to a contact zone at a rate in the range of 0.2 to 5 moles per mole of aromatic hydrocarbon. A process according to claim 32, wherein hydrogen is supplied to a contact zone at a rate in the range of 0.2 to 1.5 moles per mole of aromatic hydrocarbon. 3 ^. A process according to any one of claims 22 to 33, wherein the aromatic hydrocarbon is contacted with hydrogen at a temperature in the range of from 80 to 350 ° C.