CS218565B2 - Catalyser for selective production of the p-dialkylbenzenes - Google Patents

Description

The invention relates to a catalyst suitable for the selective production of p-dialkyl-substituted benzenes.

Disproportionation of aromatic hydrocarbons in the presence of zeolite catalysts has been described by Grandio et al. In Oll and Gas Journal vol. 69, No. 48 (1971). U.S. Pat. Nos. 3,126,422, 3,413,374, 3,598,878, 3,598,679, and 3,660,961 disclose vapor phase disproportionation on various catalysts. These processes produce an equilibrium mixture of xylenes containing about 24% o / o para-, 54% meta and 22% ortho-isomer.

Of the xylene isomers, m-xylene is the least desirable, while p-xylene is of particular importance since it is suitable for the production of terephthalic acid, which is an intermediate product in the manufacture of synthetic fibers. Mixtures of xylene isomers, either alone or together with ethylbenzene, containing an equilibrium concentration of p-xylene, were previously separated by expensive super-refractionation or multi-step freeze-drying.

In the context of the invention, a catalyst has now been found which has the ability to convert many of the available raw materials with sufficient selectivity to p-dialkylbenzenes. The catalyst according to the invention consists of a crystalline aluminosilicate zeolite having an activity of 2 to 5000, a xylene sorption capacity of more than 1 g / 100 g of zeolite, an o-xylene sorption time of 30% of the above capacity of more than 10 minutes, the sorption capacity and time sorptions are measured at 120 ° C and a pressure of 0.6 + 0.1 kPa, an S1O2 / Al2O3 ratio of 12 to 3000 and a C-index (constraint index · defined below) ranging from 1 to 12.

A catalyst which satisfies the above requirements and which is therefore able to catalyze with the desired selectivity of conversion may be formed in various forms, the following forms being preferred.

According to a first preferred embodiment, the determining factor is the crystal size of the zeolite, wherein at least a portion of the zeolite is to be present in the form of crystals having a size of 0.5 to 20 μη, preferably 1 to 6 µm.

According to a second preferred embodiment, the catalyst achieves its properties by coking, in particular by depositing coke in an amount of 15 to 75% by weight, based on the weight of the non-coked catalyst, preferably in an amount of 20 to 40% by weight. of an unquenched catalyst.

According to a third preferred embodiment, the prescribed activity and sorption properties are achieved with zeolite which is perfectly mixed with in each case 2 to 30% by weight of the zeolite, of one or more hardly reducible oxides, in particular antimony, phosphorus, boron, uranium, magnesium, zinc and / or calcium.

In a particularly preferred embodiment, the zeolite is admixed with 0.25 to 25% by weight of phosphorus oxide and magnesium oxide, the amount of phosphorus oxide preferably being 0.7 to 15 and the amount of magnesium oxide being 1 to 15%.

According to a fourth preferred embodiment, the prescribed properties are achieved in that the interior of the zeolite crystalline structure contains 0.1-10% by weight of the zeolite weight of the amorphous silica added, preferably the proportion of this silica is 2-10% by weight. According to one suitable method, the added amorphous silica is a decomposition product of a silicon compound capable of siloxanes or polysilanes or their monomethyl, monochloro or monofluorivatives. Particularly suitable silicon compounds have the general formula to enter the zeolite pores, such as silicones Si R 1 R 2 R 3 R 4 wherein each of the symbols

R 1 and R 2 are hydrogen, fluoro, chloro, methyl, ethyl, amino, methoxy, or ethoxy,

R 3 is hydrogen, fluoro, chloro, methyl or amino and

R 4 is hydrogen or fluoro.

Other suitable compounds are silane, dimethylsilane, dichlorosilane, methylsilane, or silica fluoride.

The fifth preferred embodiment differs from the fourth embodiment in that the desired properties are imparted to the catalyst by silica which is not present in the internal crystalline structure. According to this embodiment, a silica coating is provided on the outer surface of the zeolite in an amount of from 0.5 to 30% by weight, based on the zeolite. The silica may be a decomposition product of a silicon compound that cannot enter the pores of the zeolite, as a compound of the general formula wherein each symbol

R 1 and R 2, which are the same or different, are fluoro, hydroxy, alkyl, aralkyl, alkylaryl or fluoroalkyl, and

In addition, R 1 can also represent hydrogen, n is from 10 to 1000, wherein R 1 or R a contains from 1 to 10 carbon atoms.

The silicon compound preferably has a molecular weight of 500 to 20,000, preferably

1000 to 10 000. Particularly suitable compounds include dimethylsiloxane, diethylsiloxan, phenylmethylsiloxane, methyl hydrogen, ethylhydrogensiloxan, fenylhydrogensiloxan, methylethylsiloxan, fenylethylsiloxan, diphenylsiloxane, methyltrifluorpropylsiloxan, ethyltrifluorpropylsiloxan, polydimethylsiloxane, tetrachlorfenylmethylsíloxan, tetrachlorfenylethylsiloxan, tetrachlorfenylhydrogensiloxan, tetrachlorfenylfenylsiloxan, and methylvinylsíloixan ethylvinylsiloxan.

As preferred zeolites, zeolites ZSM-5, ZSM-11, ZSM-12, ZSM-35 or ZSM-38 are used in the catalysts of the invention and are generally preferred in a form characterized by the presence of hydrogen cations. Preferred catalysts are further those in which the zeolite has activity and in the range of 5 to 200.

The catalyst does not have to consist exclusively of zeolite, but can be as well composed of a zeolite mixture as the above zeolite with a binder, for example a refractory natural or synthetic type oxide. Suitable natural oxides are montmorillonite or kaolin, suitable synthetic oxides are silica, alumina, magnesium oxide, zirconia, thorium, beryllium and / or titanium dioxide. When used, the binder may comprise 1 to 99%, preferably 20 to 95% by weight of the catalyst. The preferred content is 30 to 40% by weight.

The present invention further provides a process for the selective production of p-dialkylbenzenes wherein each of the alkyl groups contains 1 to 4 carbon atoms, characterized in that the C 1 -C 4 monoalkylbenzene, the C 2 -C 18 olefin and / or C 2 -C 44 paraffin or any mixture thereof of the aforementioned compounds with benzene under conditions of conversion with the catalyst described above. Preferred conversion conditions are: temperature 250 to 750 ° C, pressure 9,81 kPa to 9,81.10 ³ kPa and mass hourly space velocity 0.1 to 2000 hr ^-1 .

The disproportionation or alkylation of toluene with a C 1 -C 4 alkylating agent can be carried out with very good results at a temperature of 400 to 700 ° C, a pressure of 98.1 to 9.81.10 ³ kPa and a mass hourly space velocity of 0.1 to 100 h ^-1. . The preferred space velocity for the two conversions is 1 to 50 h ^-1 . The same conditions may also be applied to the batch consisting of C12-C44 paraffins. The cis olefins are reacted with the above catalyst at a temperature of 300 to 700 ° C, a pressure of 9.81 to 9.81 x ³ kPa and a space velocity of 1 to 1000 h -1 to produce the desired p-dialkylbenzenes.

The most useful products obtainable by the process of the invention are p-xylene, p-diethylbenzene or p-ethyltoluene. In some cases, their yield can be increased by carrying out the reaction in the presence of hydrogen at a molar ratio of hydrogen to hydrocarbon feed of conveniently between 2 and 20.

The above catalyst is particularly suitable for the selective production of C 1 -C 4 -alkyl-substituted benzenes containing C 1 -C 4 alkyl such that a hydrocarbon precursor such as C 1 -C 4 monoalkyl-substituted benzene, C 2 -C 18 -olefins or C 2 -C 4 -olefins. The C44-paraffin or a mixture thereof is contacted under such conversion conditions with such a catalyst.

According to a preferred embodiment of the invention, the conversion of specific precursors to xylenes is carried out in which the proportion of p-xylene is substantially higher than its normal equilibrium concentration, and is preferably greater than 40% by weight, based on the xylene product. The conversion according to the invention is carried out in the presence of a specific catalyst at a temperature of 250 to 750 ° C, a pressure of 9.81 to 9.81 x ³ kPa, at a mass hourly space velocity of 0.1 to about 2000 h ^-1 . The mass hourly space velocity of the feed is based on the weight of the catalyst mixture, i.e. the total weight of active catalyst and binder. The product leaving the reaction zone is subjected to separation and distillation to obtain the desired product, for example p-xylene. Unreacted product is recycled to the next reaction.

Figure 1 shows the change in selectivity to p-xylene versus different sorption time for 30% xylene sorption capacity of the zeolite used.

Giant. 2 shows a comparison of selectivity to p-xylene achieved with crystalline aluminosilicate zeolite as a catalyst having both small and large crystal size.

Giant. 3 shows changes in toluene conversion and selectivity to p-xylene as a function of catalyst operating time using toluene and hydrogen as a common batch.

The hydrocarbon precursor used in the process of the invention may be monoalkyl substituted benzene having 1 to 4 carbon atoms in the alkyl substituent such as toluene, C2-C18 olefin such as ethylene, propyl, butenes, pentenes, hexenes, heptenes, octenes, nonenes, decenes, pentadecenes or mixtures thereof; or C12 -C44 paraffins, such as butane, hexane, octane, dodecane, eicosan, dotriacontane, tetracontane, or mixtures thereof. Preferably, these paraffins have a straight or only slightly branched chain.

A typical process within the scope of the invention is the disproportionation of toluene to benzene and xylene, in which the proportion of the obtained p-xylene is substantially higher than its normal equilibrium concentration. Such a process is effectively carried out at a temperature in the range of about 400 to 700 ° C, under pressure

9,81.10 ³ to 98.1 kPa at a weight hourly space velocity of about 1 to about 50 h ^-1.

Another suitable feedstock for the process of the invention is a stream rich in C 2 -C 15 -olefins. Thus, using the catalyst described above, ethylene, propylene, butenes, pentenes, hexenes, marrows such as butadiene, pentadienes, cycloolefins such as cyclopentene and cyclohexene, alkyl-substituted cycloolefins such as ethylcyclopentene, cyclopentadiene and cyclohexadiene can be effectively converted into p- dialkylsubstituted benzenes. Conversion of such olefin feed is carried out at about 300 to 700 ° C and a pressure from atmospheric pressure to 9,81.10 ³ kPa at a WHSV of from about 1 to about 1000 h ^_1. The sources of the olefinic reactant may be either substantially pure streams containing Ca-C18 olefins or streams obtained from refining or chemical processes which contain a high proportion of the reactant, i.e. generally greater than 25% by volume.

Yet another feedstock that can be effectively selectively processed by the process of the invention into p-dialkyl-substituted benzenes containing C1-C4 alkyl groups is paraffinic hydrocarbons having from 3 to 44 carbon atoms. Representative examples of such paraffins include butanes, pentanes, hexanes, heptanes, octanes, dodecanes, eiconsanes, dotriacontanes, tetracontanes and alkyl substituted paraffins. A paraffinic batch of this type is contacted with the above-described zeolite-type crystalline aluminosilicate catalyst at a temperature of from about 400 to about 700 ° C, a pressure of from about atmospheric pressure to about ⁹ kPa and a mass hourly space velocity of about 0.1 to about 100 h -1.

Mixtures of flavoring agents may also be used as sticks. For example, a mixture of ethylbenzene and toluene is converted selectively into a mixture rich in p-diethylbenzene and p-ethyltoluene, with p-ethyltoluene predominating when a high ratio of toluene to ethylbenzene is used in the feed.

Reaction of benzene, toluene, ethylbenzene, propylbenzene or butylbenzene with C2-C20 olefins or C5-C25 paraffins at 250-500 ° C gives p-dialkylbenzenes. This reaction is preferably carried out at an overpressure greater than 1.38 MPa.

For example, benzene and ethylene in a molar ratio of 1: 2 to 10: 1 give p-diethylbenzene in addition to ethylbenzene (pressure 2.76).

MPa, temperature 415 ° C); toluene and 1-octene of 18565 provide p-ethyltoluene and a mixture of n- and isopropyltoluene rich in p-isomer.

In the absence of added aromatics, both the C 21 -C 18 olefins and the C 22 -C 44 paraffins provide a mixture of aromatics rich in p-dialkylbenzenes. The olefins and higher paraffins are more reactive and require less stringent operating conditions, for example 230 to 600 ° C, and preferably 300 to 330 ° C, while lower paraffins, for example C3-C3 paraffins, provide aromatics in a practically usable yield only above 400 ° C. The aromatization can be carried out under atmospheric or elevated pressure. Low hydrogen partial pressure can be used to slow the aging of the catalyst. However, a high hydrogen partial pressure above 1.38 MPa results in a decrease in aromatic formation. Higher pressure and lower temperatures favor the production of p-dialkylated benzenes containing higher alkyl groups than C 1, for example p-ethyltoluene arises from either dodecane or 1-butene at 400 ° C, while p-xylene is formed as dialkylbenzene at higher temperature .

The methylation of toluene in the presence of the above-described catalyst, especially a catalyst on which carbonaceous deposits (coke) are deposited, is carried out by contacting toluene with a methylating agent, preferably methanol, at a temperature of about 300 to about 730 ° C, preferably about 400 to about 700 ° C.

At higher temperatures, zeolites with a high silica / alumina ratio are preferred. For example, a ZSM-3 catalyst with a SiO2 / Al2O3 ratio of 300. or higher is very stable at higher temperatures. The reaction is typically carried out at atmospheric pressure, but the pressure may be in the range of about 100 psig to about 60 psig. The weight hourly space velocity as used in this process is typically about 1 to 2000 h ^_1. The molar ratio of methylating agent to toluene is usually from about 0.03 to about 3. Using methanol as the methylating agent, a molar ratio of methanol to toluene of about 0.1 to about 8 moles of methanol per mole of toluene is suitable. Using other methylating agents, such as methyl chloride, methyl bromide, dimethyl ether or dimethylsulfide, the molar ratio of methylating agent to toluene may vary within the above range. The reaction is conveniently carried out at a mass hourly space velocity in the range of from about 1 to about 2000, preferably from about 3 to about 1300 hr ^-1 (i.e., parts by weight of the feed per part by weight of catalyst per hour). The reaction product, consisting predominantly of p-xylene, together with relatively smaller amounts of m-xylene and o-xylene, can be used. separated by any suitable means, for example by passing through a water condenser, whereupon the organic phase is fed to a column in which the xylene isomers are chromatographically separated.

In accordance with the present invention, the feedstock hydrocarbon precursors described above are contacted under conversion conditions with a catalyst bed consisting of a crystalline aluminosilicate having 1) an activity defined by a value and in the range of about 2 to about 5 ° C; 1 g / 100 g zeolite and 3) o-xylene sorption time for 30 ° / of the above capacity greater than 10 minutes, the sorption capacity and sorption time are measured at 120 ° C and xylene pressure 0.6 + 0.1 kPa.

The α value reflects the relative activity of the catalyst relative to the highly active silica-alumina cracking catalyst. For the determination and values as used in the substrates, the conversion of n-hetane at about 338 ° C is determined. The conversion is varied by varying the space velocity in the n-hexane conversion range of 10 to 60%, a constant per unit volume of zeolite is determined, and this value is compared to the value for a silico-alumina catalyst whose activity at 338 ° C serves as a reference value. The catalytic activity of the catalysts is then expressed as a multiple of this standard value, i.e. the value for the silico-aluminum standard. The silico-alumina reference catalyst contains about 10 wt% alumina, the remainder being silica. This method of determining the α-value (modified method described above) is thoroughly described in J-ournal of Catalysis, Vol. VI, pp. 278-287, 1966.

The measurement of hydrocarbon sorption capacities and sorption velocities is conveniently performed gravimetrically on thermo-balances. This measurement has shown that the catalyst would be sufficiently selective for p-dialkylsubstituted benzenes, it must have an equilibrium sorption capacity of xylene, either p-, m-, o-xylene or a mixture thereof, preferably p-xylene, since this isomer achieves equilibrium in the shortest time, at least 1 g per 100 g zeolite, measured at 120 ° C and 0.6 x 0.1 kPa xylene pressure, and further having an o-xylene sorption time for 30 ·% of this capacities greater than 10 minutes (under the same temperature and pressure conditions).

Zeolites, which have a very high selectivity in the preparation of p-dialkylbenzene, require a very long time, up to 1000 minutes or more, for the sorption of o-xylene in an amount of 30% of the total sorption capacity of xylene. For these substances it is preferable to determine the sorption time to a lower degree of sorption, for example a sorption time of 3, 10 or 20% of the sorption capacity. The sorption time for 30% capacity can then be estimated using the following formula (in the case of measuring the sorption time for 3% capacity) to, 3 = F. this, 03 where 3 means sorption time for · 30% capacity, it.os means sorption time for 5% capacity,

F represents a factor whose value for the sorption time for 5, 10 and 20 ° / o capacities is given in the table below% of capacity The value of the factor F serves for the sorption time for 30% sorption capacity

536

109

202.2

The determination of the crystal size of the zeolite can be carried out by conventional electron microscopy (SEM), the smallest dimension of the crystal being taken as the dimension of the crystal. The crystalline aluminosilicate zeolites, which form an essential component of the catalysts of the invention, are characterized in that their crystal size is greater than about 0.5 µπι. The amount of zeolite having this crystal size should be such that the zeolite has a controlling effect on the desired selective production of p-dialkyl-substituted benzenes. Typically, the predominant amount of zeolite present in the catalyst, i.e., above 50% by weight and preferably up to 100% by weight, has the above crystal size.

In addition to electron microscopy, measuring the hydrocarbon sorption capacity and sorption rate is useful as a means for selecting crystalline aluminosilicate zeolites effective as catalysts in the method of the invention. These measurements are expediently carried out gravimetrically on thermo-balances.

The deposition of carbonaceous deposits on the catalyst, commonly referred to as " coke ", which results from the decomposition of hydrocarbons, usually takes place during the reaction, such as the methylation of toluene in the presence of the described catalyst at a higher temperature. Pre-coking of the catalyst is usually carried out by first using the desired non-coking catalyst reaction, during which the coke is deposited on the catalyst surface. The amount of coke on the catalyst is then controlled in the above range from about 15 to about 75% by weight of the periodic regenerations which are performed by exposing the catalyst to an oxygen atmosphere at elevated temperature.

One advantage of using the catalyst described above is the ease with which it is regenerated. After using the precoking catalyst to carry out the desired reaction for a time such that the activity of the catalyst is reduced to the point where further use is uneconomical, the catalyst can be easily regenerated by burning excess coke in an oxygen atmosphere, e.g. air, usually at about 400 DEG-700 DEG. In this operation, the catalyst may be substantially free of coke, so that the catalyst needs to be subjected to precoking, or the catalyst may be partially cured of the coke regeneration, with the remainder of the coke deposits, i.e. an amount of approximately 15 to 75% by weight is left on the catalyst surface. The catalyst thus regenerated can then be further used in the desired selective production of p-xylene.

According to a preferred embodiment of the invention, a crystalline aluminosilicate zeolite may be used after a preliminary modification consisting in selective coking, i.e., at least about 1% by weight and usually about 2 to about 40% by weight carbonaceous deposits on the catalyst surface. The weight of the whole catalyst. When zeolite is used in substantially pure form or in combination with a binder causing small coking, such as silica, the weight percent of coke on the catalyst is usually in the range of 2 to 10% by weight. When the zeolite is combined with a binder that has a high tendency to coke, such as alumina, the coke content of the total catalyst is in the range of about 1 to 40% by weight. The precursion can be carried out by contacting the catalyst with a hydrocarbon feed, for example toluene, under very stringent conditions or alternatively at a reduced hydrogen / hydrocarbon concentration ratio, i.e. at a ratio of 0 to 1 mol of hydrogen to hydrocarbon. sufficient time to eliminate the desired amount of coke on the catalyst.

Preliminary modification of zeolite can suitably also be performed such that the zeolite is combined with a small amount, usually about 2 ^and about 30 ^hours motnostmmi% OBT ^{Iz some} redu ^to ovatelného oxide such as antimony oxide, phosphorus, boron, magnesium, uranium, zinc and / or calcium. The mixing of the desired oxide with the zeolite can readily be accomplished by mixing the zeolite with a solution of a suitable compound of the element to be introduced, then drying the catalyst and finally converting the calcining compound of the element into the oxide form.

According to a preferred embodiment, the aforementioned modification by means of hardly reducible oxides is carried out by simultaneously introducing phosphorus and magnesium oxide into the catalyst. The preparation of such a catalyst (which is particularly effective in toluene disproportionation) is carried out in two stages. In the first step, the zeolite crystals are such that they are substantially free of alkali metal, i.e., containing less than about

1.5 wt.% Of the alkali metal, and in which at least a portion of the original associated cations are replaced by hydrogen cations, are contacted with the phosphorus compound.

Representative phosphorus-containing compounds are derivatives falling within the group of compounds defined by the general formulas

РХз, RPX2, R3P, ХзРО, (ХОз) РО, (ХО) зР, КзР =,, RsP = S, R2PX, RPOž, RPS2, R'P (O) (OX) 2, RP (S) (SX) 2, R2P (O) OX, R ₂ P (S) SX, RP (OX) _2, RP (SX) 2, ROP (OX) 2, RSP (SX) _2, (RS] 2PSP (SR) 2, and ( RO) 2POP (OR) 2 where

R is alkyl or aryl, such as phenyl,

X is hydrogen, R or halogen.

These compounds include primary phosphines of formula RPH2, secondary phosphines of formula R2PH and tertiary phosphines of formula R3P such as butylphosphine, tertiary phosphine oxides of formula R3PO such as tributylphosphine oxide, tertiary phosphine sulfides of formula R3PS, phosphonic acids of primary formula RP (O) (OX) 2 and secondary formulas R2P (.O) OX, such as benzenephosphonic acid, the corresponding thioderivatives of formulas RP (S] (SX) 2 and R2P (S) SX, phosphonic acid esters such as diethylphosphonate of formulas (RO) 2P (O) H, dialkylalkylphosphonates of formulas ( RO) 2P (O) R and alkyldialkylphosphinates of formulas (RO) P (O) R2, phosphoric acids of formula R2POX such as diethylphosphoric acid, phosphites of primary formula (RO] P (OX) 2, secondary formulas (ROJ2POX and tertiary formulas (ROJsP) esters such as monopropyl ester, alkyldialkylphosphinites of formula (ROJPR2 and dialkylalkylphosphonite esters of formula (ROjZPR). The corresponding thioderivatives may also be used as compounds of formulas (RSjzPfSJH, (RS) p (SJR, (RS) P (S) R2, R2 PSX, (RS) P (SX) 2, [RSaPSX, (RS) 3P, (RS) PR2, and (RS) 2 ^! PR. Examples of phosphorous acid esters include trimethyl phosphite, triethyl phosphite, diisopropyl phosphite, butyl phosphite and pyrophosphites such as tetraethylpyrophosphite. The alkyl groups in said compounds contain 1 to 4 carbon atoms.

Other suitable phosphorus-containing compounds include phosphorus halides such as phosphorus trichloride, bromide and iodide, alkylphosphorodichloridities of formula [ROJPCI2, dialkylphosphorochloridities of formula (ROJ2PX), dialkylphosphionochloridities of formula R2PCI, alkylalkylphosphonochloridates of formula (RO) (R) P (O) Cl, dialkylphosphorochlorides R2P (OJC1 and RP (O) C12) The corresponding thioderivatives of formulas (RSJPCI2, (RSJPX, (RS) (R) P (S) C1 and RzPfSjCl) may also be used.

Preferred phosphorus-containing compounds are diphenylphosphine chloride, trimethylphosphite and phosphorus trichloride, phosphoric acid, phenylphosphinoxy chloride, trimethylphosphate, diphenylphosphoric acid, diphenylphosphinic acid, diethylchlorothiophosphate, acid methylphosphate and other reaction products of alcohols with phosphorus pentoxide.

The reaction of the zeolite with a phosphorus compound is carried out by contacting the zeolite with the phosphorus compound. When the phosphorus compound used is liquid, it can be used as a solution in a solvent to treat the zeolite. Any solvent that is relatively inert to the compound used and to the zeolite can be used. Suitable solvents are water and liquid aliphatic, aromatic hydrocarbons or alcohols. If the phosphorus-containing compound is, for example, trimethylphosphite or liquid phosphorus trichloride, a hydrocarbon solvent such as n-octane may be used. Liquid phosphorus-containing compounds can also be used without solvent as pure liquid substances. If the phosphorus-containing compound is in the gas phase, for example when phosphorus trichloride is used, it can be used as such or used in admixture with a gaseous diluent that is relatively inert to the phosphorus-containing compound and to the zeolite, such as air or nitrogen, or with an organic solvent such as octane or toluene.

The zeolite may be dried before being reacted with the phosphorus-containing compound. The drying may be carried out in the presence of air and may be carried out at higher temperatures. However, the temperature used should not be so high as to disrupt the crystalline structure of the zeolite.

The phosphorus-containing catalyst is also preferably subjected to heating after preparation and before use. The heating may be carried out in the presence of oxygen, for example air, and may be carried out at a temperature of about 150 ° C. Preferably, however, the catalyst is heated to higher temperatures, i.e. up to about 500 ° C for 1 to 5 hours, but may be heated for longer, for example up to 24 hours or more. Although temperatures of about 500 ° C may be used, this is not necessary. At temperatures of about 1000 ° C, the crystalline structure of the zeolite begins to deteriorate. After heating in air at elevated temperatures, phosphorus is present as an oxide.

The amount of phosphorus oxide introduced into the zeolite should be at least 0.25% by weight. Preferably, however, the amount of phosphorus oxide in the zeolite is at least 2% by weight, especially when the zeolite is mixed with a binder, for example 35% by weight of alumina. The amount of phosphorus oxide may be up to about 25% by weight or more, depending on the amount and type of binder present. Preferably, the amount of phosphorus oxide introduced into the zeolite is in the range of about 0.7 to about 15% by weight.

The amount of phosphorus oxide introduced into the zeolite by reaction with elemental phosphorus or a phosphorus-containing compound is dependent on several factors. One of these is the reaction time, i.e. the time for which the zeolite and the phosphorus-containing source are maintained in contact with each other. As the reaction time increases, more phosphorus is introduced into the zeolite at constant values of other factors. Other factors upon which the amount of phosphorus introduced into the zeolite depends are the reaction temperature, the concentration of the phosphorus compound with the reaction mixture, the degree to which the zeolite was dried before reaction with the phosphorus-containing compound, drying conditions of the zeolite after reaction of the zeolite with the phosphorus-containing compound. binders mixed with zeolite.

Magnesium oxide is then introduced into the phosphorous-containing zeolite by contacting the zeolite with a suitable magnesium compound. Representative magnesium containing compounds include magnesium acetate, magnesium nitrate, magnesium benzoate, magnesium propionate, magnesium 2-ethylhexanate, magnesium carbonate, magnesium formate, magnesium oxalate, magnesium amide, magnesium bromide, magnesium hydride, magnesium lactate, magnesium laurate, magnesium laurate, magnesium palmitate, magnesium salicylate, magnesium stearate and magnesium sulfide.

The reaction of the zeolite with the magnesium compound is carried out by contacting the zeolite with the magnesium compound. If the magnesium compound used is liquid, it can be used as a solution in a solvent to treat the zeolite. Any solvent that is relatively inert to the compound used and to the zeolite can be used. Suitable solvents are water and liquid aliphatic, aromatic hydrocarbons or alcohols. Liquid magnesium-containing compounds can also be used without solvent as pure liquid substances.

If it contains. the magnesium compound in the gas phase may be used as such or may be used in admixture with a gas diluent which is relatively inert to the magnesium containing compound and to the zeolite, such as helium or nitrogen, or an organic solvent such as octane or toluene.

After introduction of the magnesium-containing compound and prior to use, the zeolite may preferably be heated. The heating may be carried out in the presence of oxygen, for example air, and may be carried out at a temperature of about 150 ° C. Preferably, however, the catalyst is heated to higher temperatures, i.e. up to about 500 ° C for 1 to 5 hours, but may be heated for longer, for example, up to 24 hours or more. Although temperatures above about 500 ° C can be used, this is not usually necessary. At temperatures of about 1000 ° C, the crystalline structure of the zeolite begins to deteriorate. After heating in air at elevated temperatures, magnesium is present as an oxide.

The amount of magnesium oxide introduced into the zeolite should be at least 0.25% by weight. Preferably, however, the amount of magnesium oxide in the zeolite is at least 1% by weight, especially when the zeolite is mixed with a binder, for example 35% by weight of alumina. The amount of magnesium oxide may be up to about 25% by weight or more, depending on the amount and type of binder present. Preferably, the amount of magnesium oxide introduced into the zeolite is in the range of about 1 to about 15% by weight.

The amount of magnesium oxide introduced into the zeolite by reaction with a solution of the magnesium compound and subsequent calcination in air is dependent on several factors. One of these is the reaction time, i.e. the time during which the zeolite and the magnesium-containing source are kept in contact with each other. As the reaction time increases, more magnesium is introduced into the zeolite at constant values of other factors. Other factors on which the amount of magnesium introduced into the zeolite depends are the reaction temperature, the concentration of the magnesium compound in the reaction mixture, the degree to which the zeolite was dried before reaction with the magnesium-containing compound, drying conditions of the zeolite after the zeolite reaction. and a type of binder mixed with zeolite.

After contacting the phosphorous-containing zeolite with the magnesium-containing reagent, the resulting catalyst is dried and heated in a manner similar to that described for the preparation of the phosphorous-containing zeolite.

In another variation, another preferred catalyst of the invention, which is particularly useful in the selective disproportionation of toluene to p-xylene, is a catalyst in which the zeolite contains dispersed amorphous silica within its crystalline structure until it is formed. The amount of silica introduced is at least about 0.1% by weight, and is usually in the range of about 2 to 10% by weight.

Suitably, such a catalyst is prepared by adsorption of a silicon-containing compound, usually siline, into the pores of a crystalline aluminosilicate zeolite having the aforementioned silica / alumina ratio and a C-index. The molecular dimensions of the silicon compound used are such that they readily adsorb from the pores of the crystalline aluminosilicate zeolite. The adsorbed silicon compound contained in the pores of the crystalline aluminosilicate is subjected to catalyzed hydrolysis either by base catalyzed hydrolysis, i.e. by contact with an aqueous ammonia solution or by acid catalyzed hydrolysis in the presence of a Lewis or Bronsted acid, for example using an aqueous hydrochloric acid solution. calcination in air at a temperature in the range of about 300 to 700 ° C to form amorphous silica contained in the pores of the crystalline aluminosilicate zeolite.

The preparation of the modified zeolite is preferably carried out in such a way that the zeolite crystals are in a form substantially free of alkali metal, i.e. containing less than about

1.5 wt.% Of an alkali metal, which, preferably at least a portion of the original associated cations are replaced with hydrogen, are contacted with a silicon-containing compound having a molecular size such that it is immediately absorbed into the pores of the zeolite. Generally, a silicone compound of the general formula is used as the silicon-containing compound

Ri

AND

R4 — Si — R?

AND

R3 wherein each of the symbols

R1 and R2 are hydrogen, fluoro, chloro, methyl, ethyl, amino, methoxy or ethoxy,

R 3 is hydrogen, fluoro, chloro, methyl, amino or methoxy and

R 4 is hydrogen or fluoro.

Other suitable silicon-containing compounds are siloxanes, such as disiloxanes, trisiloxanes and higher siloxanes, up to decasiloxanes, and polysilanes, such as disilanes, trisilanes and higher silanes, up to decasilanes. It is also possible to use derivatives of the abovementioned siloxanes and polysilanes containing methyl, chlorine or fluorine substituents in which the silicon atom contains no more than 1 such substituent.

The silicon compound used can be styrene with the zeolite in the form of either a liquid or a gas under conditions. The zeolite pores are preferably, but not necessarily, saturated with a liquid or gaseous silicon compound. Then, the silicon compound is subjected to the catalysed hydrolysis described above, for example by contacting the sorbed silicon compound-containing zeolite with a suitable acid or base for a time sufficient to effect the desired hydrolysis. Hydrolysis releases hydrogen. The resulting product is then calcined in an oxygen-containing atmosphere, for example in air, at a temperature in the range of about 300 to 700 ° C for 1 to 24 hours, to form a catalyst containing a specific crystalline alumino-silicate zeolite containing silica in its internal structure.

The amount of silica introduced into the zeolite depends on several factors. One is the time the zeolite and the silicon-containing source are kept in contact with each other. With increasing contact time, the amount of silica introduced into the zeolite increases with the constant value of other factors. Other factors on which the amount of silica introduced into the zeolite depends are the temperature, the concentration of the silicon compound used in the sorption medium, the degree to which the zeolite was dried before contact with the silicon-containing compound, hydrolysis conditions and calcination of the zeolite after contacting the zeolite with the silicon compound. and the amount and type of binder mixed with the zeolite.

Alternatively, the modified zeolite comprises a silica coating deposited on its outer surface. This coating extensively covers the outer surface of the zeolite, with silica being contained almost exclusively on the outer surface, although a number of factors influence the final location of the silica. The silica coating is deposited on the surface of the zeolite by contacting the zeolite with a silicon compound having a molecular size that cannot penetrate the zeolite pores and then heating in an oxygen-containing atmosphere such as air at a temperature above 300 ° C, but below the temperature at which the zeolite crystallinity is impaired. The heating rate is selected such that the silicon compound does not flow out before it is oxidized to silica.

Compounds of the general formula are used as silicon coating compounds

--Are - O-i fy. >

where,

R 1 is hydrogen, fluoro, hydroxy-, alkyl-, aralkyl-, alkaryl- or fluoroalkyl.

The hydrocarbon substituents usually contain 1 to 10 carbon atoms and are preferably methyl or ethyl groups.

R2 represents the same substituents as R1, except for sodium, and n represents a number of at least 10 and usually a number of from 10 to 1000.

The molecular weight of the silicon compound used is usually about 500 to about 20,000, preferably about 1000 to 10,000.

Representative silicone compounds include dimethyl siloxane, diethylslloxan, phenylmethylsiloxane, methyl hydrogen, ethylhydrogensiloxan, fenylhydrogensiloxan, methylethylsiloixan, fenylethylsiloxan, diphenylsiloxane, methyltrifluorpropylsiloxan, ethyltrifluorpropylsiloxan, polydimethylsiloxane, tetrachlorfenylmethylsiloxan, tetrachlorfenylethylsiloxan, tetrachlorfenylhydrogensiloxan, tetrachlorfenylfenylsiloxan, methylvinylsiloxane and ethylvinylsiloxan.

The silicon compound dissolved in a suitable solvent, such as n-hexane, pentane, heptane, benzene, toluene, chloroform, carbon tetrachloride, is contacted with the above-described zeolite at a temperature of about 10 to about 100 ° C for a time sufficient to store the desired amount. silicon on the surface of the zeolite. The contact time is usually in the range of 0.2 to 5 hours during which time the mixture is evaporated. The residue is then calcined in an oxygen-containing atmosphere, preferably in air, at a rate of 0.2 to 5 ° C / min up to a temperature above 300 ° C, but below the temperature at which the zeolite crystallinity is impaired. Generally, the temperature is below 600 ° C and preferably the calcination temperature is in the range of 350 to 550 ° C. The product is kept at a calcination temperature for usually 1 to 24 hours. A silica-coated zeolite is obtained containing about 0.5 to about 30% by weight and preferably about 1 to 15% by weight of silica.

Zeolites such as zeolite X, zeolite Y, ZSM-4, faujasite, mordenite, ferrierite and offretite, which exhibit the above-defined activity and sorption properties, are within the scope of the invention. Particular preference is given to zeolites in which the silica / alumina ratio is at least 12 and which have a C-inde.x value of approximately cd 1 to 12. These zeolites cause the transformation of aliphatic hydrocarbons into aromatic hydrocarbons in industrially useful yields and are generally highly efficient in conversions including aromatic hydrocarbons. They have an extremely low alumina content, i.e. a high silica / alumina ratio, and are very effective even at a silica / alumina ratio higher than 30. This activity is surprising since the activity of zeolites is usually attributed to the aluminum atoms in the backbone and the cations associated with these aluminum atoms. These zeolites retain their crystallinity for a long time despite the presence of steam, even at high temperatures, which cause an irreversible collapse of the crystalline backbone of other zeolites, such as type X or A. In addition, carbonaceous deposits, if any, can be removed normal temperature. In many media, zeolites in this class have a very low coke formation tendency, which results in being put into operation between two firing regenerations for a long time.

An important feature of the crystal structure of this class of zeolites is that they allow limited entry and exit of intracrystalline free space by having pore dimensions greater than about 5 A and pore windows of about dimensions that would form 10-membered rings of oxygen atoms. Of course, it should be appreciated that these rings are those formed by the regular placement of tetrahedrons forming the anionic backbone of the crystalline aluminosilicate, with the oxygen atoms themselves bound to silicon or aluminum atoms located in the middle of the tetrahedra. In summary, preferred zeolites suitable for use in the method of the invention have the following combination of properties: a silica / alumina ratio of at least about 12 and a structure guaranteeing limited access to the free crystalline space.

The silica / alumina ratio can be determined by conventional analysis. This ratio should represent as accurately as possible the ratio in the solid anionic backbone of the zeolite crystal and should not include aluminum in the binder or in cationic form or in any other form located in the channels. While zeolites with a silica / alumina ratio of at least 12 can be used, it is preferred to use zeolites with a higher ratio of at least about 40. Especially preferred is the use of zeolites with a silica / alumina ratio of at least 70. Such zeolites have a higher intracrystalline sorption capacity for activation. n-hexane than for water, i.e., exhibit hydrophobic properties. This hydrophobic character is believed to be advantageous in the process of the invention.

Zeolites useful as catalysts in the process of the invention freely absorb n-hexane and have a pore size greater than about 5 A. In addition, their structure must allow limited entry for some larger molecules. Sometimes, based on the known crystalline structure, it can be judged whether there is an entry restriction. For example, when the pore windows in the crystal are made up of only eight-membered rings of oxygen atoms, the entry of molecules with a larger cross-section than n-hexane is substantially eliminated and the zeolite is not suitable for the purposes of the invention. Preference is given to zeolites with 10-ring windows, although exaggerated ripple or pore clogging may render these zeolites almost ineffective. Zeolites with twelve-membered ring windows usually do not exhibit sufficient limitations and do not achieve the advantageous conversions required by the invention, although, for example, there are corrugated products such as TMA offretite, known as an effective zeolite. There may be other such structures that are suitable due to pore blocking or other causes.

A more effective way of determining whether a zeolite exhibits the necessary "input restriction" than that predicted by the crystalline structure is by simply determining the "constraint index" (C-index) by taking a small sample of zeolite weighing about 1 g or a mixture of equal amounts of n-hexane and less is continuously passed through. 3-methylpentane at atmospheric pressure. The procedure is as follows. A sample of zeolite in the form of pellets or extrudates is crushed to particles of approximately coarse sand size and placed in a glass tube. Prior to testing, the zeolite was treated with an air stream of 538 ° C for at least 15 minutes. The zeolite is then flushed with helium and the temperature is adjusted between 288 and 510 ° C to ensure a total conversion of between 10 and 60%.

The hydrocarbon mixture is passed at hourly space velocity of liquid phase 1 liquid hydrocarbon volume / catalyst volume per hour by zeolite at a dilution with helium such that the molar ratio of helium to total hydrocarbon is 4: 1.

After 20 minutes of operation, a sample of the stream exiting the tube is taken and analyzed, most preferably by gas chromatography, to determine the unconverted proportions of the two hydrocarbons.

The C-index is calculated as follows:

C-index = logio (remaining n-hexane) logio (remaining 3-methylpentane)

C-mdex approximates the ratio of the cracking rate constants of the two hydrocarbons. Catalysts suitable for the purposes of the invention are those which. they contain a zeolite having a C-index in the range of 1.0 to 12.0. The C-ndex values of some typical zeolites are as follows:

Zeolite C-index

ZSM — 58.3

ZSM — 118.7

ZSM — 122

ZSM — 382

ZSM — 354.5

TMA offretit3,7

Beta0,6

ZSM — 40.5

H — Zeplon 0.4

REY0.4 amorphous silica / alumina0.6 erionit38

It will be appreciated that the above-mentioned C-index values typically characterize said zeolites, but that they are a composite result of several variables used in their determination and calculation. As a result, the C-index of the zeolite to be tested may vary within a range of approximately 1 to 12, depending on the temperature used, falling within the aforementioned 288 to above range.

510 ° C and a corresponding conversion in the range of 10 to 60%. Other variables, such as the size of the zeolite crystals, the possible presence of occluded impurities and the perfect blend with the zeolite may also influence the C-index value. Thus, it will be apparent to those skilled in the art that although the C-index is a highly useful means of characterizing suitable zeolites, it is an approximate value which is dependent on the assay method, and that in some cases it may have limit values. In all cases, however, any zeolite that is interesting in terms of this. An alternative of the invention has a C-index measured at a temperature in the range of 289 to above

511 ° C, about 1-12 ° C.

Examples of zeolite classes defined above include zeolites ZSM-5, ZSM-11,

ZSM — 12, ZSM — 35, ZSM — 38 and other similar materials. ZSM-5 is described and protected in US Patent No. 3,702,886. ZSM-11 is described in detail in US Patent No. 3,709,979 and

ZSM-12 in U.S. Patent No. 3,832,449.

The ZSM-38 zeolite can be identified by the molar ratio of anhydrous oxides as follows:

(0,3-2,15) R2O: (0-0,8) θ2θ: Al2O3:> 8 SiO2 where represents

R is an organic nitrogen cation derived from a 2- (hydroxyalkyl) trialkylammonium compound and a

Alkali metal cation.

This zeolite is also characterized by a specific powder X-ray pattern.

Preferably, the zeolite is synthesized in such a form that its zeolite is synthesized. the anhydrous ratio of oxides corresponded to the following ratio:

(0,4-2,5JR2O: (0-0,6) θ2θ: AI2O3: xSiO2 where

R represents an organic nitrogen cation derived from a 2- (hydroxyalkyl) triacylammonium compound in which the alkylene is methyl, ethyl or a mixture thereof,

M represents an alkali metal, especially sodium, and x is a number greater than 8 and up to about 50.

Synthetic zeolite ZSM-38 has a certain characteristic structure allowing its resolution. The x-ray diffraction pattern contains the significant lines shown in the table. I. It is clear that the X-ray diffraction pattern (significant lines) is similar to that of natural ferrierite, with the important exception that the natural ferrierite X-ray patterns contain a significant line at 11.33 A.

Table I d (A) 1/0

9.8 + 0.20 strong 9.1 + 0.19 medium 8.0 + 0.16 weak 7.1 + 0.14 medium 6.7 + 0.14 medium 6.0 + 0.12 weak 4.37 + 0.09 weak 4.23 + 0.09 weak

Table I - continued

I / Od (A)

4.01 + 0.08 3.81 + 0.08 very strong very strong 3.69 + 0.07 medium 3.57 + 0.07 very strong 3.51 + 0.07 very strong 3.34 + 0.07 medium 3.17 + 0.06 strong 3.08 + 0.06 medium 3.00 + 0.06 weak 2.92 + 0.06 medium 2.73 + 0.06 weak 2.66 + 0.05 weak 2.60 + 0.05 weak 2.49 + 0.05 weak

Another characteristic of ZSM-38 is its sorption capacity. Zeolite ZSM-38 has

R +

The wider range is the higher sorption capacity for 2-methylpentane (due to the sorption of n-hexane, as evidenced by the sorption ratio of n-hexane / 2-methylpentane) compared to the hydrogen form of natural ferrierite obtained by calcination of the form containing cation exchanged ammonium . The characteristic sorption ratio of n-hexane / 2-methylpentane for ZSM-38 (after calcination at 600 ° C) is less than 10, while the same ratio for natural ferrierite is substantially greater than 10, for example 34 or even higher.

The ZSM-38 zeolite may conveniently be prepared by preparing a solution comprising a source of an alkali metal oxide, preferably sodium oxide, organic nitrogen oxide, alumina and silica, and water having a composition defined as the ratio of oxides in the following range:

Preferred range

R @ + + M @ +

OH— / SiO2

H2O / OHSO2 / A12O3

0.2 - 1.0

0.05 - 0.5 - 500

8.8 - 200

0.3 —0.9

0.07 - 0.49

100 - 250 - 60 where represents

R is an organic nitrogen cation derived from a 2- (hydroxyalkyl) trialkylammonium compound and a

The alkali metal M ion and the mixture is held until zeolite crystals are formed. (The amount of OH 'groups is calculated only from inorganic alkali sources and does not include the contribution of organic bases). Then the crystals are separated from the liquid. Typically, the reaction mixture is heated to about 90 ° C to about 400 ° C for about 6 hours to about 100 days. A more preferred temperature range is about 150 ° C to about 400 ° C, and the time required at this temperature is about 6 hours to about 80 days.

Digestion of the gel particles is continued until crystals are formed. The solid product is then separated from the reaction medium, for example by cooling the mixture to room temperature, filtering and washing. The crystalline product is then dried, for example 8 to 24 hours at 110 ° C.

The ZSM-35 zeolite can be identified by the anhydrous molar ratio as follows:

(C-, 3-2.5) R2O: · (0-0.8) θ2θ: Al2O3:> 8 SiO2 where represents

An organic nitrogen cation derived from ethylenediamine or pyrrolidine; and

Alkali metal cation,

This zeolite is also characterized by a specific powder X-ray pattern.

Preferably, the zeolite is synthesized in such a form that its anhydrous oxide ratio corresponds to the following ratio:

(0,4-2,5JR2O: (0-0,6) ΜΜ Ο: AI2O3: xSiCh where

R represents an organic nitrogen cation derived from ethylenediamine or pyrrolidine,

M is an alkali metal, especially sodium, and x is a number greater than 8 - up to about 50.

Synthetic zeolite ZSM-35 has a certain characteristic structure, allowing as a resolution. The x-ray diffraction pattern contains the significant lines shown in Table II. Obviously, the X-ray diffraction pattern (significant lines) is similar to that of natural ferrierite, with the important exception that the natural ferrierite X-ray patterns containing the significant line at 11.33 A. Detailed examination of some individual ZSM-35 samples reveals very weak This line, however, is not an important line characteristic of ZSM-35.

Table II d (A)

I / Io

9.6 + 0.20

7.10 + 0.15

6.98 + 0.14

6.64 + 0.14

5.78. + 0.12 5.68 '+ 0.12 4.97' + 0.10

4.58 + 0.09

3.99 + 0.08 3.94 + 0.08

3.85 + 0.08

3.78 + 0.08 3.74 + 0.08 3.66 + 0.07

3.54 + 0.07

3.48 + 0.07 3.39 + 0.07 3.32 + 0.07 3.14 + 0.06 2.90 + 0.06

2.85 + 0.06 2.71 + 0.05

2.65 + 0.05 2.62 + 0.05

2.58 + 0.05

2.54 + 0.05

2.48 + 0,05 very strong to very strong medium medium medium weak mild weak mild mild moderate medium strong mild moderate very strong very strong weak weak - medium weak - medium weak weak weak weak weak weak weak

Another characteristic of ZSM-35 is its sorption capacity. Indeed, the ZSM-35 zeolite has a higher sorption capacity for 2-methylpentane (relative to the sorption of n-hexane, which is evident from the n-hexane / 2-methylpentane ratio) compared to the hydrogen form of natural · ferrierite obtained by calculating the form containing ionic cations exchanged ammonium ions. The n-hexane / β-methylpentane sorption ratio for ZSM-35 (after calcination at 600 ° C) is less than 10, while the same ratio for natural ferrierite is substantially higher than 10, for example 34 or even higher.

The ZSM-35 zeolite may conveniently be prepared by preparing a solution comprising an alkali metal oxide source, preferably sodium oxide, organic nitrogen containing oxide, alumina and silica, and water having a composition defined as the ratio of oxides in the following range:

Wider range

Preferred range

R- + + Μ-ψ OH- / SiO2 Щ0 / 0Н S1O2 / A13O3

0.2 - 1.0

0.05 - 0.5 - 500

8.8 - 200

0.3 - 0.9

0.07 - 0.49

100 - 250 - 60 where it represents

An organic nitrogen cation derived from pyrrolidine or ethylenediamine; and

M. an alkali metal ion, and the mixture is held until the zoolite crystals are formed. (The amount of OH groups is calculated from inorganic alkali sources only and does not include the contribution of organic bases.) The crystals are then separated from the liquid. Typically, the above reaction mixture is heated for about 6 hours to about 10D days. to a temperature of about 90 ° C to about 400 ° C A more preferred temperature range is about 150 to about 400 ° C, with the time required at a temperature in the range of about 6 hours to about 80 days.

The gel particles are digested until crystals are formed. The solid product is then separated from the reaction medium, for example by cooling the mixture to room temperature, filtering and washing. The crystalline product is then dried, for example 8 to 24 hours at 110 ° C.

The specific zeolites described above are substantially catalytically inactive when prepared in the presence of organic cations, possibly because the organic cations originating from the solution used in their manufacture occupy the intercrystalline free space. Such zeolites can then be activated by heating in an internal atmosphere at 538 ° C for 1 hour, then, for example, base exchange with ammonium salts and finally calcination at 538 ° C in air. The presence of organic cations in the solution used for the preparation may not be absolutely necessary for the formation of a special type of zeolite, however, their presence seems to affect the preferential formation of this special type of zeolite. Most often, it is expedient to activate this type of zeolite by base exchange using ammonium salts, after which it is calcined in air at about 538 ° C. about 15 minutes to about 24 hours.

Sometimes natural zeolites can be converted to this type of zeolite by various activation procedures and other treatments such as base exchange, steam treatment, alumina extraction and calcination, either alone or in combination. Natural minerals that can be treated include ferrierite, brewsterite, stilbit, dachiardite, epistilbit, heulandite and clinoptilolite. Preferred crystalline aluminosilicates are ZSM-5, ZSM-11, ZSM-12, ZSM-38, and ZSM-35, with ZSM-5 being particularly preferred.

According to a preferred embodiment of the present invention, zeolites suitable as catalysts are products which do not have a crystalline backbone density of less than about 1.6 grams per cm 3 in the dry state in hydrogen form. It has been found that zeolites that meet all three of the above criteria are the most suitable, as they tend to favor the production of hydrocarbon products with a boiling point range of petrol. Thus, preferred catalysts of the invention are those zeolites having the above-mentioned C-index in the range of from about 1 to about; 12, a silica / alumina ratio of at least about 12, and a crystal density in. not less than about 1.6 g / cm ³ dry state. The dry state density of known structures can be calculated by adding the number of silicon and aluminum atoms per 1000 cubic A, as shown, for example, on WM Meier's Zeolite Structure. The cited article is part of the Society of Chemical Industry, London, 1968. Proceedings of the Conference on Molecular Sieves, London, April, 1967. When the crystal structure is unknown, the density of the crystal skeleton can be determined by the classical pycnometric method. For example, it can be determined by immersing the dry hydrogen form of the zeolite in an organic solvent that is not sorbed by the crystal. It is possible that the unusually sustained activity and stability of this zeolite class is due to the high density of the anionic crystal backbone, which should not be less than 1.6 g / cm ³ . This high density must of course result in a relatively small free space in the crystal, which is likely to make these structures more stable. On the second . however, free space is important as a site of catalytic activity.

The density of the crystalline backbone of some typical zeolites is as follows:

Zeolite Empty volume Skeletal density

Ferrierite 0.28 cm ³ / cm ³ 1.76 g / cm ³ Mordenite 0.28 1.7 ZSM-5 0.29 1.79 Dachiardit 0.32 1.72 L 0.32 1.61 Clinoptilolite 0.34 1.71 Laumontit 0.34 1.77 ZSM-4 Omega 0.38 1.65 Heulandit 0.39 1.69 P 0.41 1.57 Offretit 0.40 1.55 Levynite 0.40 1.54 Erionite 0.35 1.51 Gmelinit 0.44 1.46 Chabazit 0.47 1.45 AND 0.5 1.3 Y 0.48 1,27

When the zeolite is synthesized in the form of an alkali metal, it can conveniently be converted to a hydrogen form generally via the intermediate formation of the ammonium form. This is done by subjecting the alkali metal form to ion exchange with an ammonium ion and calcining the ammonium form to form a hydrogen form. In addition to the hydrogen form, the zeolite can also be used in other forms in which the original alkali metal content is reduced to less than 1.5% by weight. The original alkali metal ions in the zeolite may be replaced by other suitable ions of the group IB by ion exchange. to VIII. periodic tables such as nickel, copper, zinc, palladium, calcium and rare earth metals.

In carrying out the desired conversion method, it may be desirable to introduce the above-described crystalline aluniinosilicate zeolites into another temperature-resistant material and other conditions used in the process. These matrix forming materials may be synthetic or naturally occurring substances and inorganic materials such as clays, silica and / or metal oxides. The metal oxides may be present as they occur in nature, or in the form of gelatinous precipitates or gels formed by mixtures of silica and metal oxides. Naturally occurring clay that can be blended with zeolite include montmorillonite and kaolin type clays. Said type of clay includes subbentonites and kaolins of various origins and other materials in which the main mineral component is halloysite, kaolinite, dickite, nakrit or anauxite. These clays can be used in the raw state as obtained in mines or after pretreatment by calcination, acid treatment or chemical modification.

In addition to these materials, the zeolites used in the process of the invention may be mixed with. materials that form a porous matrix, such as alumina, silica-alumina, silica-magnesium, silica-zirconia, silica-thorium, silica-beryllium, silica-titanium dioxide, or titanium dioxide, or titanium dioxide; , for example, silica ~ alumina - thorium oxide, silica - alumina - zirconia, silica - alumina - magnesium oxide, and silica - magnesium oxide · - zirconium oxide. The matrix may be in the form of a cogel. The relative ratio of the zeolite component and the inorganic oxide component of the gel matrix may vary within wide limits, i.e. the zeolite content may be about 1 to about 99 weight percent, and more usually about 5 to 80 weight percent, based on the resulting mixture.

The conversion process according to the invention can be carried out as a discontinuous, senicontinuous or continuous process using a catalyst system. fixed or movable bed. After use, the catalyst is directed to a regeneration zone where it is freed from carbonaceous deposits, i.e. coke, at elevated temperature by firing in an oxygen-containing atmosphere, for example in air. The regenerated catalyst is then recycled to the conversion zone where it is re-contacted with the feedstock. It is very advantageous to carry out the conversion according to the invention in the presence of hydrogen at a molar ratio of hydrogen to hydrocarbon precursor in the range of about 2 to 20, at a hydrogen pressure in the range of 98.1 kPa to 9.81. 103 kPa. The presence of hydrogen in the reaction zone greatly reduces the aging rate of the catalyst.

Although the above process is further described by way of example for the selective preparation of p-dimethylsubstituted benzenes such as p'-xylene, it should be appreciated that other p-dialkylsubstituted benzenes in which alkyl groups contain 1 to 4 carbon atoms can be selectively produced in the same manner. . By selecting a suitable precursor, a mixture of ethylbenzene and toluene can be selectively converted to ethyltoluene using the technique described in the Backgrounds, similarly dodecane or 1-butene can be converted to p-ethyltoluene in addition to p-xylene; butylbenzene can be selectively converted to dibutylbenzene.

The following examples serve to illustrate the invention in more detail, but do not limit the scope thereof in any way. *

Example 1 kg of sodium silicate (type Q) is mixed with 23.8 kg of water. The resulting solution is designated as solution A. 0.61 kg of commercial grade aluminum sulphate [A12S (O45.14 H2O), 7.13 kg of commercial grade sodium chloride and 1.58 kg of sulfuric acid (96.5 wt% H2SO4) are added. mixed with 32.5 kg of water, the resulting solution is designated as solution B. 1.17 kg of water are introduced into an autoclave equipped with a stirrer, solution A and solution B are mixed in a nozzle and injected simultaneously into the autoclave. 1.28 kg of tri-n-propylamine and 1.10 kg of n-propyl bromide are then added to the contents of the autoclave and the mixture is allowed to react with stirring at 160 DEG C. After 20 hours at 100 DEG C. The autoclave mixture was sampled and the solid product was found to be 100% ZSM-5 by X-ray diffraction, and after a total reaction time of 28.7 hours at 160 ° C, the autoclave content was cooled. deionized water containing 3500 ppm Pri mafloc C-7 (polyammonium bisulfate) until the decanted water is free of chloride The solid product is filtered off and dried at 121 ° C.

500 g of the dried filter cake obtained as product are calcined under nitrogen at 538 ° C for 3 hours. 444 g. Of the calcined product are stirred for 1 hour at ambient temperature with 2220 ml of 1 N ammonium nitrate solution. The mixture was filtered under vacuum. The ion exchange is repeated. The filter cake is washed with 1776 ml of water and the solid product is dried at 121 ° C. The hydrogen content of the final product is less than 0.01%.

The resulting catalyst had a crystal size of 1-2 activity and 162, a p-xylene sorption capacity of 6.5 weight percent, and an o-xylene sorption time for 30% of this capacity of 92 minutes. Measurement of the last two values is performed at 120 ° C. When measuring the sorption of p-xylene, the hydrocarbon partial pressure is 679.8 Pa. In determining the sorption time of the o-xylene, the hydrocarbon partial pressure is 506.5 Pa.

Example 2

Toluene was passed through the catalyst of Example 1 at a temperature of 550 ° C and an overpressure of 2.69 MPa at an hourly space velocity of 50 h ^-1 at a hydrogen / hydrocarbon ratio of 6. The toluene conversion was 20.1 weight percent and the p-xylene yield based on xylene is 30%.

Example 3

The catalyst of Example 1 was treated with toluene at 640 ° C, hourly space velocity of 50 hi and a pressure of 98.1 kPa for 5 hours. 4% by weight of coke is deposited on the catalyst. The catalyst thus treated absorbs 6.1 g of p-xylene per 100 g of zeolite at 120 ° C and p-xylene pressure

679,8 Pa. The sorption time of the o-xylene to · 30% xylene capacity, measured at 120 ° C and the o-xylene pressure of 506.5 Pa, is 6000 minutes. The catalyst has a value of 281.

A catalyst containing about 4 percent by weight of coke is contacted with toluene at 550 ° C, an overpressure of 4.14 MPa, an hourly space velocity of 40 h1 and a hydrogen / hydrocarbon molar ratio of 10. The liquid product contains 80.7 percent by weight of toluene (19, 3% conversion) and 9.6 weight percent xylenes and benzene. The xylene portion contains 82 percent p-xylene.

Example 4 4 g of the catalyst of Example 1 are contacted with a solution containing 1.02 grams of magnesium acetate tetrahydrate in 4 ml of water. The resulting suspension was evaporated to dryness in air for 24 hours and then the residue was calcined at 538 ° C for 10 hours to give the product HZSM-5 containing 6 weight percent magnesium oxide. The catalyst absorbs 6.3 g of p-xylene per 100 g of zeolite at 120 ° C and a p-xylene pressure of 679.8 Pa. The sorption time of the o-xylene at 120 ° C and the o-xylene pressure of 506.5 Pa to 30% of the o-xylene capacity is 583 minutes. The catalyst has a 129 value of 129.

Example 5

The catalyst of Example 4 is contacted with toluene at a temperature of 550 ° C, a pressure of 40 psi, a mass hourly space velocity of 40 and a hydrogen / hydrocarbon ratio of 4. The toluene conversion is 29.4%. The liquid product contains 15.3 weight percent xylene containing 53% of the β-isomer.

Example 6

Zeolite HZSM-5 with a crystal size of approx

0,03 μΐη is produced as follows:

(a) preparing the solution

Silicate solution

40.9 kg silicate. sodium,

23.7 kg of water,

118 g of Daxad 27 dispersant (sodium salt of polymerized substituted benzenoid alkylsulfonic acid mixed with a suspending agent).

Acid solution

1430 g A12 (SO4) 3xH O (molecular weight = 595),

3440 g H2SO4

4890 g NaCl,

24.3 kg H2O.

Additional solids

2840 g NaCl,

2390 g of n-propyl bromide, 4590 g of methyl ethyl ketone,

Additional liquid

1180 g H2O.

(b) Procedure

The silicate solution and the acid solution are mixed in a mixing nozzle to form a gel which is sprayed into a 114-liter autoclave to which 1180 grams of water is introduced.

The gel is whisked by stirring, 2840 g of sodium chloride are added and mixed thoroughly. After stirring, the organic solution is added to overlay the gel. The autoclave is sealed and heated to about 104 ° C without stirring and held under these conditions for 14 to 15 hours to pre-react the organics. At the end of this pre-reaction period, the initial crystallization period begins with stirring. After about 75 to 80 hours, the temperature is raised to 160 ° C and held for about 3 hours to complete the crystallization. Excess unreacted organic matter is removed by vigorous evaporation and the contents of the autoclave are cooled and the autoclave is emptied. The product was analyzed by X-ray diffraction and determined to be 100% crystalline zeolite ZSM-5. Chemical analysis thoroughly washed. the crystalline product is as follows:

weight percent molar ratio AlaOs 2.21 1.0 SiO2 94.9 72.8 On 0.81 - Na20  - 0.82 N 0.67 2.48 C <· 8.2 35.6

After thorough washing and drying at about 121 ° C, the zeolite is converted to the catalytic form using the following multi-step procedure:

(a) Preliminary calcination is carried out in a 100% nitrogen atmosphere at 538 ° C for 3 hours. at atmospheric pressure at a controlled speed of 2.8 ^e C / min from ambient temperature to 538 ° C.

b) An ion exchange is performed with! N ammonium nitrate solution at room temperature for 1 hour using 5 ml reagent solution per gram zeolite.

c) Wash the zeolite with 4 volumes of water.

d) Repeat steps b] and c) and air dry at 121 ° C.

The analysis revealed that the cation exchange zeolite contained 0.01 wt. It has an o-xylene sorption capacity of 5.6% by weight of sodium. and the sorption time of o-xylene at 30 ·% of this capacity is less than 1.3 inin. Both measurements are performed at 120 ° C and 506.5 Pa of the hydrocarbon.

Example 7

Toluene was passed through the microcrystalline catalyst HZSM-5 of Example 6 at a pressure of 98.1 kPa at 600 ° C at a hourly space velocity of 50. The toluene conversion was 15 wt. % and the yield of p-xylene based on xylenes is 25%, i.e. about a normal equilibrium concentration of p-xylene.

Example 8

The catalyst prepared according to Example 6 is mixed with alumina and extruded. A catalyst of 65 weight percent zeolite and 35 weight percent alumina is obtained. After using the resulting catalyst for the toluene disproportionation under various regeneration conditions, toluene is passed through the catalyst at a temperature of 474-521 ° C at a pressure of 3 bar, a hydrogen / hydrocarbon ratio of 0.5 and a mass hourly space velocity of 5-6.3. h ^_ 1 for 38 days.

The coke content after this time is 45 g / 100 g of catalyst. The sorption capacity of p-xylene, measured at 679.8 Pa, is 2 g per 100 g of zeolite and the sorption time of o-xylene for 30% of the xylene sorption capacity is 2900 minutes. The sorption time is measured at a pressure of 506.5 Pa.

The catalyst has a value of 20. The toluene is passed over the catalyst at 521 ° C at 3.1 MPa, a mass hourly space velocity of 6.3 h ^-1 and a hydrogen / hydrocarbon ratio of 0.5. The toluene conversion is 37% by weight and the yield of p-xylene based on the xylenes produced is 43%.

Example 9

The catalyst was prepared by adding 3 g of the catalyst of Example 1 to a solution of 0.3 g of magnesium nitrate hexahydrate in 2.2 ml of water. The suspension is mixed thoroughly and calcined in air by heating to 538 ° C. The heating was carried out at a rate of 1.6 ° C per minute, and then the catalyst was held at 538 ° C for 10 hours. The resulting catalyst contained 2.4 weight percent magnesium. Its sorption capacity is 5.2 g p-xylene per 100 g zeolite at 120 ° C and p-xylene pressure 679.8 Pa. At 120 ° C and an o-xylene pressure of 506.5 Fri, the sorption time for 30% xylene capacity is 2600 minutes. The catalyst has a value of 36.

Example 10

The toluene is passed through the catalyst of Example 9 at 550 DEG C., 4 psig, a hydrogen / hydrocarbon ratio of 4 weight per hour space 10. The toluene conversion is 20 weight percent and the p-xylene yield based on xylenes is 45 percent .

Example 11

A sample of 5 g of HZSM-5 catalyst of the type described in Example 6 is placed in a glass tube equipped with a glass frit disc. Dimethylsilane was passed through the HZSM-5 bed at a rate of 40 ml / min. After 15 minutes, 0.60 g of dimethysilane is absorbed in HZSM-5. The product was added to 200 mL of 15% aqueous ammonia to hydrolyse the silane. Hydrogen evolves rapidly. After 1 hour, the product was filtered off and calcined at a rate of 1 ° C / min to a temperature of 538 ° C for 6 hours.

The above procedure is repeated a total of three times. HZSM-5 is obtained with a silica content of 5% by weight.

The catalyst absorbs 4.1 g of o-xylene per 100.

grams of zeolite at 120 ° C and o-xylene pressure

506,5 Pa. 30% of the sorption capacity is reached in 2.7 minutes.

Example 12

Toluene is passed through the catalyst of Example 11 at a temperature of - 600 ° C, a pressure of 98.1 kPa, a mass hourly space velocity of 40 and a hydrogen / hydrocarbon pressure 2. The toluene conversion is 2% by weight and the yield of p-xylene based on xylenes is 62%. With a more realistic conversion of toluene, for example 20 percent, the selectivity to p-xylene is only 27 percent, i.e. the p-xylene concentration is substantially the same as the equilibrium concentration, indicating that the sorption time to reach 30% of the sorption capacity is 2. 7 min is too low.

Example 13 g of NH4-ZSM-5 having a crystal size of 0.03 µm is suspended in a solution of 5.35 g of orthoboric acid in 40 ml of water at 80 ° C. The suspension was left overnight (16.5 hours) at 90 ° C and then poured into a 30 X 50 mm crystallization dish and placed in an oven thermostated at 110 degrees Celsius. The contents of the dish are often mixed until a uniform dry powder is formed. The temperature is gradually raised to 200 ° C and the catalyst is left at this temperature for 1 to 2 hours. It is then transferred to an oven for annealing at 500 ° C in the same open crystallization dish for 17.5 hours. The theoretical amount of boron present in the form of the oxide is 4.06 wt. The powder is pressed into plates and crushed and sieved. 14 - 20 mesh sieve fractions are used.

The catalyst obtained absorbs 3.1 g of p-xylene at 120 ° C and a p-xylene pressure of 679.8 Pa. At 120 ° C and an o-xylene pressure of 506.5 Pa, the sorption time to 30% capacity is 270 minutes. The catalyst has an α-value of 3.8.

Example -14

Via 5 g of the catalyst - according to example 13 - at 600 ° C and 98.1 kPa pressure, the mass per hour space velocity is conducted.

4.5 toluene. The toluene conversion was 11.9 wt% and the yield of p-xylene relative to xylenes was 74%.

EXAMPLE 15 g of a zeolite of the type described in Example 6 are mixed with 6.5 g of antimony methoxide and 75 ml of p-xylene. The suspension was refluxed under nitrogen for 17 hours. The solid is washed with 100 ml of toluene, then with 100 ml of methanol - and 100 ml of n-hexane. The product is air dried and placed in a vacuum oven where it is left at 100 ° C for 3 hours. Then the product is calcined in air at 538 ° C for 10 hours. The product contains 24 wt. % antimony.

The catalyst absorbs 3.5 g of p-xylene per 100 grams of zenlite at 120 DEG C. and p-xylene pressure.

679.8 - Pa. At 120 ° C and an o-xylene pressure of 506.5 Pa, its sorption time for 30% xylene capacity is 89 minutes. The catalyst has an α-value of 8.

Example 16

10 'g of the ammonium form - ZSM-5 - is suspended in a solution of 5 g of uranyl dinitrate hexahydrate in 20 ml of water. The suspension was heated to 73 ° C and allowed to stand overnight. The entire contents of the vessel are then poured into a crystallization dish and the dish is placed in an oven heated to 130 ° C. The catalyst is stirred every 30 minutes. After about 2 hours, when the catalyst has the appearance of a dry powder, it is placed in a 500 ° C oven where it is left to stand overnight. The final weight of the calcined catalyst is 12.17 g. The catalyst has a xylene sorption capacity at 120 degrees Celsius and a xylene pressure of 599.8 ± 106.6 Pa and 6.3 g of xylene per 100 g of zeolite. The sorption time of the o-xylene at 120 ° C at a pressure of 506.5 Pa to 30 percent of the sorption capacity is 4.8 minutes. The catalyst has an «value of 83.

Example 17

Toluene is ^passed through a mass hourly space rate of 3.5 h at a pressure of 98.1 kPa at a temperature of 550 ° C through the catalyst of Example 16. The toluene conversion was 46% by weight and the yield of p-xylene, based on the xylenes, was 24%.

Example 18

Dissolve 11.6 g of magnesium acetate tetrahydrate in 25 ml of water. To the solution was added 10 g of 1/8 pellet ammonium form of crystalline zeolite ZSM-5. The catalyst is - - left - - several -. minutes - soak, - then - - the excess liquid - - separates - - and - keeps. The catalyst is placed in an oven and the water is evaporated. After cooling, the dry catalyst was added to the remainder of the magnesium acetate solution. The excess liquid is - separated - and the wet catalyst - is placed in an oven and allowed to dry. - The process is repeated until all liquid is adsorbed to the catalyst. Finally, the catalyst is placed in an oven where it is kept overnight at 500 ° C. The weight of the final catalyst was 11.56 g. The catalyst had an xylene sorption capacity at 120 ° C and a xylene pressure of 599.8 ± 106.6 Pa of 4.2 grams of xylene per 109 g of zeolite. The sorption time of the o-xylene at 120 ° C and the pressure of 506.5 Pa to 30% of the sorption capacity is 7.5 minutes. The catalyst has a -a-value of 21.

Example 19

Toluene is passed through the catalyst of Example 18 at 550 ° C at a pressure of -98.1 kPa and a mass hourly space velocity of 3.5 h ¹ . The toluene conversion is 12 wt. % and the yield of p-xylene based on xylene is 25%.

EXAMPLE 1 20 g of ammonium form ZSM-5 is added to a solution of 7.28 g of zinc nitrate hexahydrate in 20 ml of water. The suspension is heated to approximately 90 ° C and allowed to stand overnight. The entire contents of the vessel are then poured into a crystallization dish and the dish is placed in an oven at about 130 ° C. After about 2 hours, the catalyst was placed in an oven at 500 ° C and allowed to stand for about 8 hours. The final weight of the catalyst after calcination is 11.21 g. The catalyst has a xylene sorption capacity at 120 ° C and a xylene pressure of 599.8 ± 106.6 Pa of 4.9 g xylene per 100 g zeolite. Sorption time of o-xylene at 120 ° C and pressure

506.5 Pa to 30% of the capacity is 38 minutes. The value of α of the catalyst is 504.

Example 21

Over the catalyst of Example 20 at 550 ° C and 98.1 kPa leads tloku weight hourly velocity of 3.5 h ¹ toluene. The toluene conversion is 20 wt. % and the yield of p-xylene based on xylenes is 28%.

Example 22 g of acid form ZSM-5 is suspended in a solution of 12.9 g of calcium nitrate tetrahydrate in 25 ml of water. The suspension is heated to 88 ° C and allowed to stand overnight. The entire contents are then poured into a crystallization dish, which is placed in an oven at 100-130 ° C. After about 4 hours, the temperature is raised to about 200 ° C in about 2 hours. The catalyst was placed in an oven at 500 ° C overnight. The final weight of the catalyst after calcination is 12.80 g. The catalyst has a xylene sorption capacity at 120 ° C and xylene pressure of 599.8 ± 106.6 Pa; 1.2 g xylene per 10-0 g Zeolite. Sorption time of o-xylene at 120 ° C and pressure

506.5 Pa to 30% capacity is 116 minutes. The catalyst has an α value of 0.9.

Example 23

Toluene is passed through the catalyst of Example 22 at 550 ° C at a pressure of 98.1 kPa at a mass hourly space rate

3.5 h ^{_ l} . The toluene conversion is 0.4 wt. % and the yield of p-xylene based on xylenes is 67 percent.

Example 2 4 g of the ammonium form of the powdered catalyst ZSM-5 are placed in a solution of 11.6 g of magnesium acetate tetrahydrate in 25 ml of water. The suspension was heated to 95 ° C and allowed to stand overnight. The entire contents are then poured into a crystallization dish and the dish is placed in an oven heated to 56 ° C. Then

The temperature rises to 100 to 120 ° C. The suspension is often mixed until it appears to be a dry powder. The temperature was then gradually raised to 200 ° C and maintained at this temperature for about an hour. The catalyst is then placed in an oven where it is annealed at 500 ° C overnight. The final weight of the catalyst is 11.37 g. The catalyst has a xylene sorption capacity at 120 ° C and a xylene pressure of 599.8 + 106.6 Pa

4.4 g xylene per 100 g zeolite. The sorption time of the o-xylene at 120 ° C and the pressure of 506.5 Pa to 30 percent of the capacity is 655 min. The catalyst has an α-value of 24.

Example 25

Over the catalyst of Example 24 at 550 ^Q C, a pressure of 98.1 kPa and a weight hourly space velocity of 4.5 h ^_l leads toluene. The toluene conversion is 16 wt. % and the yield of p-xylene based on xylenes is 59%.

Example 26

The boron-containing ZSM-5 catalyst was prepared as in Example 13, except that 0.22 g of orthoiboronic acid was used per g of ammonium form ZSM-5. The boron content determined by calculation is

3.34 wt. %. Boron is probably present as an oxide.

Despite the above catalyst is conducted at 400 ° C, a weight hourly space velocity of 2.6 h ¹ propylene. The conversion is 94%. The resulting aromatics (25 wt%) contain 31% xylenes. The p-xylene content of the xylene fraction is 56%.

Example 27

A sample of HZSM-5 was mixed with antimony oxide in a ratio of 0.43 g Sb ₂ O _i per gram of HZSM-fifth The mixture was compressed, crushed and 8 to 14 mesh fractions were sieved. 1 g of this fraction was placed in a glass microrreactor with a length of 15-20 cm and a diameter of 14-18 mm. A reservoir for a heater is placed in the catalyst bed. The catalyst was heated to 525 ° C for 1 hour while passing nitrogen at 50 ml / min. The catalyst is left under constant nitrogen for 3 hours at 500-525 ° C and then calcined for half an hour in air (flow rate 50 ml / min). The resulting catalyst contains 30% antimony trioxide.

Example 28

A sample of HZSM-5 modified 30 Sb ₂ ; O 3, prepared according to Example 27, is placed in a vertical flow reactor. Propylene is passed through the catalyst at 400 ° C and a mass hourly space velocity of 3.0.

The propylene conversion is 90.3%. Aromates are produced with a selectivity of 14.8% and contain 185656 as the major components benzene, toluene, xylenes and ethyltoluene. The largest fraction is xylene (34 percent) containing 91% of the β-isomer.

Example 29

Another sample of HZSM-5 catalyst, modified with 30% Sb 2 O, 3 of Example 27, was used for the selective disproportionation of toluene. The toluene is passed through the catalyst in a vertically arranged fixed bed reactor at a temperature of 550 ° C, atmospheric pressure and a mass hourly space velocity of 1.0 h -1. After 6 hours of operation, the toluene conversion is 20%. Benzene and xylenes are obtained as products. The xylenes contain 81% of the β-isomer.

Example 30

As described in Example 27, another sample of the Sb2 & lt _{; 0.1} modified Modified ZSM-5 catalyst was prepared except 0.33 g of antimony trioxide was used per gram of HZSM-5. The resulting catalyst contains 25% Sb 2 O _;

Example '31

The catalyst prepared according to the example is used for the disproportionation of toluene to benzene and xylene at 550 ° C, atmospheric pressure and a mass hourly space velocity of 1 h / t. After 6 hours of operation, the toluene conversion is 9.5%. The xylene portion contains 83% xylene.

The catalyst absorbs 1.39 g of p-xylene-per-100 g of zeolite at 120 ° C and a p-xylene pressure of 679.8 Ta. At 120 ° C and o-yylene pressure of - 006.5 Pa, the sorption time for - 30% xylene capacity t (), 3 is more than 300 minutes.

Example 3 2

Catalyst · opdle Example 1 is contacted with 1-butene at 400 ^Q C · Din HO- weight space velocity of 4 h '1 .For pressure -.98,1 · psi. Liquid - the product, which forms mass. % of the feed, contains 13.4 wt.% xylene and 3.9 wt. % ethyltoluene. The xylene portion contains 37% p-xylene and the ethyltoluene portion contains 43% p-ethyltoluene. Equilibrium concentrations of these isomers are 24 and 32%, respectively.

Example 33

The catalyst of Example 1 is contacted with dodecane at 400 ° C by a mass hourly space velocity of 10 h -1 at a pressure of 98.1 kPa. The liquid product comprising 41 wt. It contains 12.6 wt.% Xylene and 4.3 wt. % ethyl · tolueek. The xylene portion contains 63% p-xylene and the ethyltoluene portion contains 58%! p-ethyltoluene.

Example 34

This example illustrates the preparation of p-diethylbenzene using the catalyst of Example 1 pretreated with toluene as in Example 1, thereby storing about 4 wt. ° / o carbonaceous deposits (coke). A 1: 2 molar ratio of benzene and ethylene (fresh feed) is mixed with a recycle stream containing benzene and ethylbenzene and passed through the catalyst at a temperature of 440 to 454 ° C and a pressure of 2.07 MPa and a mass hourly space velocity of 2 h -1. based on - kg ethylene / h / kg catalyst. It separates the recycle stream as a overhead from the reactor effluent stream. This stream contains benzene, ethylbenzene and unreacted ethylene and is recycled to the reactor. The bottom fraction contains the desired product, i.e. p-diethylbenzene.

The specific selectivity to the β-dialkylaromatic compounds obtained by the use of the catalysts described in this specification depends on the particular charge used and the operating conditions. In toluene disproportionation, the p-xylene content of the xylenes produced is highest at a low toluene conversion. In addition, it has been found that the catalysts of the present invention exhibit a very surprising and unusual property, i.e., that at some toluene conversion, the selectivity to p-xylene increases with increasing temperature - in the range of - about 400 ° C. to 700 ° C.

When comparing the para-selectivity of the different catalysts, it is therefore desirable to perform a comparison at the same operating temperature, for example 550 ° C, and at the same conversion of toluene, for example 20%, which is set at the feed rate. Para-selectivity under these reference conditions can either be measured directly or extrapolated from other actual operating conditions.

Values of -selectivity to p-xylene (p-selectivity), i.e.% p-xylene in xylene fraction, under the above standard conditions (20 ° / o conversion; at - 550 - °°) and sorption time of o-xylene up to 30 % Of the absorption capacity at 120 °

Celsius (t0.3) are shown in Table III below.

Catalyst from Example Table Sorption time of o-xylene it0,3 (min) III Selectivity to p-xylene ⁴ · Selectivity factor ⁴ · ⁴ 6 1.3 24 0 11 2.7 27 Mar: 3.7 16 4.8 25 1.3 18 7.5 24 0 20 May 38 28 5.4 1 92 39 20 May 22nd 116 38 18 13 270 48 32 5 583 69 59 24 655 53 38 9 2600 45 28 8 2900 69 59 3 6000 80 73

using toluene at 550 ° C and 20% toluene conversion. 24% · p-xylene is the equilibrium concentration of p-xylene in the xylene mixture and therefore does not indicate high selectivity.

^{+ +} selectivity factor (%; p-xylene in xylene sub-24)

The above data. are graphically depicted in the attached figure where the selectivity factor for p-xylene is plotted against the sorption time of o-xylene for 30% capacity. It is immediately apparent from the graph of FIG. 1 that catalysts having a xylene sorption time of 30%. xylene capacities greater than 10 minutes are selective for p-xylene.

Example 35 kg of sodium silicate (type Q) are mixed with 23.8 kg of water. The resulting solution is designated as · solution A. 0.61 kg of commercial grade aluminum sulphate [A13 (SO4) 3.14 H2O], 7.13 kg of commercial grade sodium chloride and 1.58 kg of sulfuric acid (96.06 wt% H2SO4) 32.5 kg of water are added and the solution is designated as solution B. Solution A and solution B are mixed in a nozzle and injected into an autoclave equipped with a paddle stirrer, then 1.28 kg of tri-amide are added to the autoclave. n-propylamine and 1.10 kg of n-propyl bromide The mixture was allowed to react at 158 rpm with stirring at 121 rpm After 14.1 hours at 158 ° C, the solid stream was analyzed by x-ray diffraction to form a product 100 % ZSM-5 with S1O21 / A / 2O3 ratio 70.

A sample of 10 g of ZSM-5 thus prepared was contacted with 500 ml of 1 N ammonium chloride solution. The ion exchange is carried out in 3 stages. The first step was carried out for 2 hours at 100 ° C, the second for 18 hours at room temperature and the third for 3 hours at 100 ° C. The product is then calcined at a rate of 1 ° C / min up to a temperature of 538 ° C. The product is held at this temperature for 10 hours. The resulting HZSM-5 has a crystal size of 1 to 2 μπι, a sorption capacity of p-xylene of 6 wt. % and sorption time of o-xylene up to 30% capacity 116 minutes. The latter two measurements are carried out at 120 ° C. In determining the sorption capacity of p-xylene, the hydrocarbon partial pressure is 679.8 Pa, and in determining the sorption time for o-xylene, the hydrocarbon partial pressure is 506.5 Pa.

Example · 36

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Example 37

Zeolite HZSM-5 with a crystal size of about 0.03 μη is produced as follows:

a) Preparation of the solution

Silicate solution

40.9 kg sodium silicate

23.7 kg of water

118 g of Daxad 27 dispersant (sodium salt of polymerized substituted benzenoid alkylsulfonic acid mixed with a suspending agent)

Acid solution

1430 g Ah (SO 4) 3. xHzO (molecular weight = 595)

3440 g H2SO4 4890 g NaCl

24.3 kg H2O

Additional solids

2840 g NaCl

2390 g of n-propyl bromide 4590 g of methyl ethyl ketone

Additional liquid

1180 g H2O

(b) Procedure

The silicate solution and the acid solution are mixed in a mixing nozzle to form a gel which is sprayed into a 114-liter autoclave to which 1180 grams of water have been introduced.

The gel is whisked by stirring, 2840 g of sodium chloride are added and mixed thoroughly. After stirring, the organic solution is added to overlay the gel. The autoclave is sealed and heated to about 104 ° C without stirring and held under these conditions for 14 to 15 hours to pre-react the organics. At the end of this pre-reaction period, an initial crystallization period is initiated by stirring at 90 rpm. After about 75 to 80 hours, the temperature is raised to 160 ° C and held for about 3 hours to complete crystallization. Excess unreacted organic matter is removed by vigorous evaporation and the contents of the autoclave are cooled and the autoclave is emptied. The product was analyzed by X-ray diffraction and determined to be 100% crystalline zeolite ZSM-5. Chemical analysis of a thoroughly washed crystalline product is as follows:

weight% mole ratio

A12O3 2.21 1.0 S1O2 94.9 72.8 On 0.81 - NaaO - 0.82 N 0.67 2.48 C 8.2 35.6

After thorough washing and drying at about 121 ° C, the zeolite is converted to the catalytic form using the following multi-step procedure:

(a) First, calcination in 100% nitrogen atmosphere is performed for 3 hours at 538 degrees Celsius at atmospheric pressure at a controlled heating rate of 2.8 ° C / min from ambient temperature up to 538 ° C.

b] An ion exchange is carried out with 1 N ammonium nitrate solution at room temperature for 1 hour using 5 ml of reagent solution per gram of zeolite.

c] The zeolite was washed with 4 volumes of water.

d) Repeat steps b) and c) and air dry at 121 ° C.

The analysis revealed that the cation exchange zeolite contained 0.01 wt. It has an α-xylene sorption capacity of 5.6% by weight of sodium. % and the sorption time of o-xylene for 30% of this capacity is less than 1.3 min. Both measurements are carried out at 120 ° C and 506.5 Pa.

Example 38

Microcrystalline Over HZSM-5 catalyst of Example 3 at a pressure of 98.1 kPa at a temperature of 600-650 ° C results in a weight hourly space velocity of 20 to 100 h ^_1 toluene. The reaction conditions and the results in% by weight are given in Table V.

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From the above results, it is clear that the amount of p-xylene in the total xylene mixture produced corresponds substantially to the p-xylene concentration of the thermodynamically equilibrium mixture.

Figure 2 shows a comparison of selectivity to p-xylene of both HZSM-5 with small crystals, i.e. about 0.03 µm, and HZSM-5 with large crystals, i.e. about 1 µm. From this comparison, it is apparent that selectivity to p-xylene is greatly improved by using a large-crystal substance. Thus, with a 10% toluene conversion, the selectivity to paraxylene is 48% using large crystals, while the selectivity to p-xylene is 27% using a small crystal.

Example 39

A sample of the HZSM-5 large crystal catalyst of Example 35 was steam treated at 560 ° C and positive pressure for 2 hours.

98.1 kPa.

Example 40

Toluene is ^passed through a large-crystal catalyst according to Example 39 at a pressure of 98.1 kPa at a temperature of about 650 ° C. The reaction conditions and measured results are shown in Table VI.

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Example 41 at a molar ratio of hydrogen to hydrocarbon 2 over the HZSM-5 large crystal catalyst of Example 39 at a pressure of 98.1 kPa and at a temperature of about 650 ° C by an hourly space velocity of 10 h ^-1 . The reaction conditions are shown in Table VII.

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Table VII

Time Temperature Weight Benzene. Toluene Xylenes *) Total Сэ + Conversion (h) C hourly, p- m- o- amount space velocity

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Comparing the results in Tables VI and VII, it is clear that the presence of hydrogen, even at a total pressure of 98.1 kPa, significantly reduces the aging rate of the catalyst, thereby significantly increasing the catalyst life and reducing the regeneration frequency.

Example 42

Toluene was passed through a sample of the HZSM-5 large-crystal catalyst of Example 39 at about 625 ° C and a pressure of 20 psig at a hourly space velocity. in the presence of hydrogen at a hydrogen to hydrocarbon molar ratio of 6.

The initial conversion was 24.8 wt. % at selectivity to p-xylene (as a percentage of total xylene mixtures) 45%. After 14 days the conversion was 21% and the selectivity to p-xylene was 82%.

The changes in toluene conversion and selectivity to p-xylene that occur during the 14-day experiment are evident from Figure 3. In particular, Figure 3 shows that the aging rate is moderate and results in a relative decrease in conversion of 1.2 -%. During this period the selectivity to p-xylene (expressed as the proportion of p-xylene in the xylene mixture) increases by 2.9% per day.

Example 43

The catalyst is prepared by heating 8.5 g of zeolite ZSM-5 containing about 10% of the smallest crystal twins of up to 3 µm and about 90%. of polycrystalline spheroids of 5 to 10 μη, 5 hours at 538 ° C in air, followed by ion exchange in three stages at room temperature using 500 ml of 1 N ammonium chloride solution for 15,3 h , 3.8 hours and 3.0 h. The obtained material was calcined in air at 538 ° C for 10 h. The resulting product has a p-xylene sorption capacity of 6.2 wt. and the sorption time of o-xylene to 30% of the capacity of 40 minutes. The latter two measurements are carried out at 120 ° C. In determining the sorption capacity of p-xylene, the hydrocarbon partial pressure is 679.8 Pa, and in determining the sorption time for o-xylene, the hydrocarbon partial pressure is 506.5 Pa.

Toluene is passed through the catalyst obtained according to Example 43 at 600 ° C at a hourly space velocity of 50 h ^-1 at a pressure of 98.1 kPa. The toluene conversion is 10.6 wt. -%. The product contains 5.1 wt. % benzene, 89.4 wt. % toluene and 5.5 wt.% xylenes. The xylene fraction contains 35.2% p-xylene.

Example 44 kg of sodium silicate [type Q) is mixed with 23.8 kg of water. The resulting solution is designated as Solution A. 0.61 kg of aluminum sulfate- [Al2 (SO4)). 14 HzO] commercial purity,

7.13 kg of commercial grade sodium chloride and 1.58 kg of sulfuric acid (96.5 wt% H2SO4) are mixed with 32.5 kg of water. The resulting solution is designated as solution B. Solution A and solution B are mixed together in a nozzle and injected into an autoclave equipped with a high shear mixer. The resulting gel was mixed in an autoclave at 90 rpm for one hour, and 1.28 kg of tri-n-propylamine and 1.10 kg of n-propyl bromide were added. The mixture is allowed to react at 160 ° C with stirring at 90 rpm. After 20 hours at 160 ° C, a sample of the mixture is taken from the autoclave and the solid product is 100% ZSM-5 using an X-ray diffraction pattern. After a total reaction time of 28.7 h at -160 ° C, the autoclave content was cooled. The resulting solid product is washed by decanting with deionized water containing 3500 ppm -Primafloc C-7 (polyammonium bisulfate) until the decanted water is free of chloride. The solid product was filtered off and dried at 121 ° C.

500 g of the dried filter cake obtained as product are calcined under nitrogen at 538 ° C for 3 hours. 444 g of the calcined product was stirred for 1 hour at ambient temperature with 2220 ml of 1 N ammonium nitrate solution. The mixture was filtered under vacuum. The ion - exchange - repeats. The filter cake is washed with 1776 ml of water and the solid product is dried at 121 ° C. The hydrogen content of the final product is less than 0.01%.

The resulting - catalyst - has a crystal size of 1 to 2 µm, a p-xylene sorption capacity of 6.5% by weight, and an o-xylene sorption time for 30% of this capacity of 92 min. Measurements The last two values are carried out at 120 DEG C. When measuring the sorption of p-xylene, the partial pressure of the hydrocarbon is 679.8 Pa. In determining the sorption time of o-xylene, the hydrocarbon partial pressure is 506.5 Pa.

Example 45

The catalyst of Example 11 is contacted with 1-butene at -400 [deg.] C, a hourly space velocity of 4-h ^-1 and a pressure of 98.1 kPa. Liquid product, consisting of 98 pots. % of the batch, -contains -13.4 wt. % xylene and 3.9 wt. % ethyltoluene. The xylene fraction contains 37% p-xylene and the ethyltoluene fraction contains 43% p-ethyltoluene. The equilibrium concentration of p-xylene in the xylene mixture is -29% and of p-ethyltoluene in the ethyltoluene mixture is 32%.

Example 46

The catalyst of Example 44 is contacted with dodecane at -400 ° C, hourly space velocity of 10 h ^-1 and a pressure of 98.1 kPa. The liquid product, which constitutes 41% by weight of the feed, contains 12.6% by weight. % xylene and 9.3 wt. -% ethyltoluene. The xylene fraction contains 63% p-xylene and the ethyltoluene fraction contains 58% p-ethyltoluene.

Example 47

The catalyst of Example 44 was contacted with toluene at 550 ° C, hourly space velocity of 50 h1, pressure of 2.5 MPa, and hydrogen / hydrocarbon molar ratio 6. The liquid product containing 20 wt. % converted toluene, consisting of 12.1 wt. ·% Xylenes, the remainder being benzene. The xylene fraction contains 30% p-xylene.

Example 48

The catalyst of Example 44 was treated with toluene at 640 ° C, hourly space velocity of 50 h ¹ and pressure of 98.1 kPa for 5 hours. 4 wt. % of coke. The catalyst thus treated is contacted with toluene at 550 degrees Celsius, at a pressure of 40 psi, an hourly space velocity of 40 h ^-1 and a hydrogen / hydrocarbon molar ratio of 10. The liquid product contains 80.7 wt. toluene (19.3% conversion) and 9.6 wt% xylenes and benzene The xylene moiety contains 82% p-xylene.

Example 49 g of the catalyst of Example 44 were contacted with a solution containing 1.02 g of magnesium acetate tetrahydrate in 4 ml of water. The resulting suspension was evaporated to dryness in air over 24 hours and then the residue was calcined at 538 ° C for 10 hours to give HZSM-5 containing 6 wt. % of magnesium oxide.

Example 50

The catalyst of Example 49 is contacted with toluene at a temperature of 550 ° C, a pressure of 40 psi, a hourly space velocity of 40 in a hydrogen / hydrocarbon ratio.

4. The toluene conversion is 29.4%. The liquid product contains 15.3 wt. % xylene containing 53% of the β-isomer.

Example 51

This example illustrates the preparation of p-diethylbenzene using the catalyst of Example 44 pretreated with toluene as in Example 1, thereby storing approximately 4 'himot. ° / o carbonaceous deposits (coke). A 1: 2 molar ratio of benzene and ethylene (fresh feed) is mixed with a recycle stream containing benzene and ethylbenzene and passed through the catalyst at a temperature of 440 to 454 ° C and a pressure of 2.07 MPa and a mass hourly space velocity of 2 h_1 based on kg of ethylene / h / kg of catalyst. From the reactor effluent, the recycle stream is separated by distillation as overhead. This stream contains benzene, ethylbenzene and unreacted ethylene and is recycled to the reactor. The bottom fraction contains the desired product, i.e. p-diethylbenzene.

Example 52

A sample of HZSM-5 catalyst having a crystal size of 0.02-0.05 µm and a weight of 5 g is placed in a glass tube equipped with a glass frit disc. The HZSM-5 bed was passed through the methylsilane at a rate of 40 ml / min. After 15 minutes, 0.60 g of dimethylsilane is absorbed in HZSM-5. The product was added to 200 mL of 15% aqueous ammonia to hydrolyse the silane. Hydrogen evolves rapidly. After 1 hour, the product was filtered and calcined at a rate of 1 ° C / min up to 538 degrees Celsius for 6 hours.

The above procedure is repeated a total of three times. HZSM-5 is obtained with a content of 5% by weight of silica.

Example 53

A modified silicone HZSM-5 catalyst was prepared, as in Example 52, except that HZSM-5 having a crystal size of 1-2 µm was used; iii. instead of HZSM-5 measuring 0.02 to 0.05 μΐη.

Toluene (5.2 parts by weight) is contacted with 0.13 parts by weight of this catalyst at a temperature of 600 ° C and a hourly space velocity of 20. The p-xylene content of the xylene product, as determined by gas chromatography, is 79%. . This number is significantly higher than the 30% p-xylene concentration achieved using the initial HZSM-5 under comparable conditions.

Example 54

To 1.42 g of phenylmethylsiloxane (molecular weight 1686) dissolved in 40 ml of n-hexane is added 4 g of NH4 ZSM-5 having a crystal size of 1 to 2 μΐη. The NH4 ZSM-5 sample contains 35% alumina as a binder. The mixture was slowly evaporated in a rotary evaporator over 2 hours. The residue was calcined in air at a rate of 1 ° C / min up to 538 ° C and maintained at this temperature for 7 h. HZSM-5 modified silicone was obtained with a silica content of 14% by weight. %.

Example 55

To 0.73 g of phenylmethylsiloxane (molecular weight 1686), dissolved in 40 ml of n-hexane, are added 4 g of NH3 ZSM-5 having a crystal size of 1 to 2 μΐη. The mixture was evaporated in a rotary evaporator over 1/2 hour. The residue is calcined in air at a rate of l / C / min up to a temperature of · 538 ° C. The product was held at 538 ° C for 7 hours. Silica modified HZSM-5 with a silica content of 7.5 wt. %.

Example 56

Κ 0.32 g of methylhydrogensiloxane (molecular weight 308-7) dissolved in 40 ml of n-hexane are added 4 g of NH 2 ZSM-5 having a crystal size of 1 to 2 µm. The mixture was evaporated in a rotary evaporator over 1/2 hour. The residue is calcined in air at a rate of 1 ° C / min to a temperature of 538 ° C. The product was maintained at 538 ° C for 7 h. Silica modified HZSM-5 with a silica content of 7.5 wt. %.

Example 57

To 0.40 g of dimethylsiloxane (molecular weight 4385) dissolved in 40 ml of n-hexane is added 4 g of NH4 ZSM-5 having a crystal size of 1 to 2 μΐη. The mixture was evaporated in a rotary evaporator over 1/2 hour. The residue is calcined in air at a rate of 1 ° C / min up to 538 ° C. The product was held at 538 ° C for 7 hours. Silica modified HZSM-5 with a silica content of 7.5 wt. %.

Example 58

A sample of silica-modified HZSM-5 prepared according to Example 57 was pelleted, sieved to separate a 14-30 mesh fraction and was tested in a flow reactor by toluene disproportionation in the presence of hydrogen at a hydrogen / hydrocarbon molar ratio of 2 and atmospheric pressure. The reaction is carried out at 550 to 600 ° C and a mass hourly space velocity of 8 to 22 h ^-1 . The results are summarized in Table VIII.

Table VIII

Catalyst Content of p-xylene wt. % Conversion of toluene wt. % Mass hourly space velocity (h-1) Temperature unmodified HZSM-5 33 20 May 20 May 550 fresh S1O3 / HZSM-5 65 7 22nd 550 56 12 11 550 46 20 May 8 550 regenerated SiO2 / HZSM-5 71 7 22nd 550 61 12 11 550 . 49 20 May 8 550 79 12 22nd 600 67 20 May 11 600

From the above data, it is clear that the selectivity to p-xylene is substantially higher after modification with silica at the same conversion and temperature, and that this selectivity remains high after the catalyst has been regenerated by burning the carbonaceous deposits with air at 540 ° C.

Example 59

A sample of HZSM-5 modified with silica, prepared according to Example 55, was se. 14 to 30 mesh fractions were sieved and tested in a flow-through. reactor. - disproportionation of toluene in the presence of hydrogen at a hydrogen / hydrocarbon molar ratio of 2 - and - atmospheric pressure. The reaction is carried out at 550 to 600 ° C and a mass hourly space velocity of 6 to 25 h -1. The results are summarized in Table IX.

Table IX

Catalyst The content of p-xylene in the mixture of xylenes by mass. % Conversion of toluene wt. % Mass hourly space velocity (h-1) Temperature unmodified HZSM-5 33 20 May 20 May 550 fresh SiO2 / HZSM-5 92 7 25 550 90 12 13 550 84 20 May 6 550 regenerated SiO21HZSM’5 94 6 25 550 92 10 13 550 86 16 6 550

From the above results it is evident that the HZSM-3 catalyst modified with silica is fully regenerable (in air at 340 ° C) and exhibits a significantly higher selectivity to p-xylene compared to the unmodified catalyst at the same conversion and pressure.

Example 60

Silica-modified HZSM-3 catalyst prepared in a similar manner to Example 33 but containing 1.9 wt. % of silica, was tested by disproporting toluene in a flow-through reactor at atmospheric pressure in the presence of hydrogen at a hydrogen / hydrocarbon molar ratio of 2. The reaction was carried out at 30 to 20 h ^-1 . The results are summarized in Table X.

Table X

The content of p-xylene in the mixture of xylenes by mass. % Conversion of toluene wt. % Mass hourly space velocity (h-1) Temperature Noc: 2 ° C 78 7 20 May 330 68 12 10 330 34 19 Dec 3 330

Example 61

A sample of HZSM-3 modified with silica, prepared according to Example 36, was tested

Tabulk

Content of p-xylene - in the mixture of xylenes mass. % Conversion of toluene wt. % 80 11 66 20 May 33 28

toluene disproportionation carried out under the conditions of Example 60. The results are shown in Table XI.

XI

Weight Hour Temperature Room Speed ° C (h-i)

20330

10330

3330

Example 62 ..

Toluene was disproporated using a silica modified HZSM-3 sample prepared as described in Example 34. The reaction was carried out at 300 ° C under a pressure of 40 psi. Hydrogen / hydrocarbon ratio. · (Molar) · is 2 and the mass hourly, spatial • velocity is 7 h_1. During - 18. · Days · of operation · · conversion decreases slightly from 38 to 36%, while the proportion of p-xylene in the xylene mixture increases from - · 38 to 70 · ·%.

Example 63 in the presence of a silica-modified HZSM-3 sample prepared according to Example 33. The toluene / methanol molar ratio is 4 and a catalyst in the form of pellets having a particle size of 14 to 30 mesh is used. The reaction is carried out at a temperature of 400 ° C to 400 ° C. 330 ^e C, · atmospheric pressure, mass hourly space velocity - 10 ¹ · per -. · Use of · hydrogen, · with · molar · hydrogen / hydrocarbon ratio. is 2. Results - are summarized in Table - XII. The high selectivity to p-xylene is apparent from the results.

The alkylation of toluene with methanol is carried out

Table - XII

The content of p-xylene in the mixture of xylenes · wt. %

Conversion of toluene wt. %

Mass Hour Temperature Room Speed ° C (h-ij

88 84 10 330 91 60 10 300 94 44 10 430 93 36 10 400

Example 64

Crystals of ZSM-5 were produced using the following substances:

Silicate solution kg sodium silicate type Q (NazO / / SiO2 = 3,3)

23.8 kg water

Acid solution

612 g aluminum sulphate 1600 g sulfuric acid 7190 g sodium chloride

32.5 kg of water

Organic substances

1290 g of tri-n-propylamine s

1110 g of n-propyl bromide.

The silicate solution and the acid solution are mixed in a nozzle to form a gel-like precipitate which is metered into a 114 µL stirred autoclave. After the gelation is complete, the organic substances are added and the temperature is raised to 157 ° C with stirring. The reaction mixture was maintained at 157 ° C for 17 hours with stirring at 121 rpm. . The product is then analyzed by X-ray diffraction and identified as ZSM-5. The product is then washed free of soluble salts and dried. Analysis of the product yields the following composition (molar ratios)

A12O3 1.0 S1O2 74.4 NazO 0.31 N 2.26 C 21.9

The thus prepared ZSM-5 is first calcined in air at 370 ° C and then exchanged for ammonium ions by treatment with 5 N NHaCl solution at 100 ° C in two steps (15 ml solution per gram of zeolite) first for 16 hours and a second time for 4 hours. The catalyst was filtered off, washed with chlorides and air dried.

The resulting ammonium form ZSM-5 (NH4 ZSM-5) is converted to the hydrogen form by calcination in air at a rate of 1 ° C / min up to 538 ° C and then held at 538 ° C for 10 hours.

A mixture of toluene (1715 g) and methanol (426 grams) in a molar ratio of 1.4 / 1 is passed through 5 g of the HZSM-5 thus prepared at 550 ° C by an hourly space velocity of 5 parts by weight / part by weight. The catalyst activity decreases from an initial toluene conversion of 70 wt. % to zero at the end of the 85 hour period. Coking increases the catalyst weight by 77%.

A portion of the coke catalyst was regenerated overnight at 550 ° C in air.

Regenerated catalyst in amount

0.8 g, containing about 30% by weight of coke, is used for the alkylation of toluene with methanol, which is carried out using a toluene / methanol mixture in a molar ratio of 1.4: 1. The alkylation is carried out at 490 ° C and weight per hour. space velocities

11.5 wt. part catalyst / h. The toluene conversion is 60% and the ratio of the p-, m- and o-isomers of xylene in the xylene fraction is 50: 33: 17.

Example 65

After use in the procedure of Example 64, the catalyst was regenerated in air at 550 ° C for 16 hours. Regenerated catalyst in an amount of 0.8 g, containing about 30 wt. Is used for the alkylation of toluene with methanol, which is carried out using a toluene / methanol mixture in a molar ratio of 1.4 / 1. The alkylation is carried out at 490 ° C and a mass hourly space velocity of 18 masses, parts of batch / mass. part catalyst / h. The toluene conversion is 49% and the ratio of the p-, m- and o-isomers of xylene in the xylene fraction is 52: 32: 16.

Example 66

The catalyst is prepared by mixing 5 wt.% HZSM-5 and 95 wt.%. % silica gel.

Methanol and toluene are passed through the catalyst in a 1: 1 molar ratio at a temperature of 550 ° C and a mass hourly space velocity of 250 h -1. The methanol conversion is 11 wt. %. After 32.5 hours of operation, the catalyst is largely deactivated due to the accumulation of coke. The selectivity to p-xylene at this point is 100% with a toluene conversion of about 1%.

Example 67

The catalyst was prepared by mixing 5 wt% HZSM-5 extrudate (containing 65 wt. _/ Vol · HZSM-5 and 35 wt.% Alumina as a binder), and 95 wt. Parts of silica gel.

Toluene and methanol were passed through the catalyst at a molar ratio of 1: 1 at 550 ° C and a mass hourly space velocity of 241 h -1. The methanol conversion is 10 wt. %. The xylene content of the aromatic product is 100%. After 4.5 hours of operation, the catalyst is largely inactivated due to the accumulation of coke. The selectivity to p-xylene at this point is 100% with a toluene conversion of about 1%.

Example 68

In a fixed bed extruded catalyst comprising 35 wt. % alumina and 65 wt. % HZSM-5, prepared according to Example 1 of VSA Patent No. 3,751,506, is contacted with a toluene feedstock with methanol at a 2: 1 molar ratio of toluene / methanol. The reactor inlet temperature is 466 ° C and the reactor pressure is maintained atmospheric. . The total hourly hourly space velocity is 4 h ^-1 . The composition of the liquid product is as follows:

Component Share of total product in weight % toluene 59.6 xylenes 129.7 p-xylene / xylene mixture 24.5 m-xylene / mixture of xylenes 52.6 o-xylene / xylene mixture 22.9 benzene 3.2 Cg 6.2 Cg-I- 1.1 other quantities of coke 0.2 catalyst after experiment in% 3.6 Example 69

The results show that the amount of coke deposited on the catalyst, i.e. 3.6 wt. %, it is insufficient to achieve selective production of p-xylene, since the ratio of p-, m- and o-xylene concentrations is substantially the same as the equilibrium ratio.

Examples 6Θ to 71

The exuded catalyst similar to that used in Example 68 is pre-coked prior to alkylation. The reaction batch and conditions are the same as in the previous example. The composition of the liquid product is as follows:

7Ό 71 amount of coke on catalyst (wt%) toluene (wt%) xylenes (wt%) content of p-xylene in xylene mixture (% ji content of m-xylene in xylene mixture (%) content of o-xylene in xylene mixture (%) benzene (wt.%)

Cg

Cg — other

30 .26 .27 72.9 7,2,4 72.8 120.7 20.6 19.8 37.8 30.0 30.7 42.3 48.6 48.1 119.9 21.4 21.2 0.2 0.5 0.4 5.6 .5,9 6.4 0.5 0, '5 0.5 0.1 0.1 0.1

From the above results, it is apparent that by depositing the coke on the catalyst within the range, the amount of p-xylene produced is increased beyond the amount corresponding to the equilibrium concentration, i.e. selectively p-xylene is produced.

Example 1 a d 72 to 80

The HZSM-5 catalyst prepared according to Example 64 is used to methylate toluene at a molar ratio of toluene to methanol of 2: 1. The inlet temperature is 466 ° C, the pressure is atmospheric and the mass hourly space velocity is 4 h ^-1 . The catalyst used in Example 72 is not pre-coked, while in the remaining Examples s ^; e uses catalysts on which the spinning has deposited various coke amounts as indicated in the table. The composition of the liquid products obtained in all cases is given in Table XIII.

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From the above results, it is clear that the catalyst must contain at least 15% by weight of the selective production of p-xylene. % of deposited coke.

From the results obtained in Example 73, it can be seen that even if the amount of coke deposited on the catalyst is greater than 8% by weight, it is equally possible to achieve a ratio of concentrations of the β-, m- and o-isomers in the mixture. xylenes, which corresponds to a substantially equilibrium ratio.

Example 81

This example describes the disproportionation of toluene in the presence of HZSM-5 catalyst, which is not modified with phosphorus and magnesium.

iCatatizer - containing 6: 5 wt. % - acid forms of ZSM-5 and 35 wt. % alumina -se is prepared as follows:

A sodium silicate solution is prepared by mixing 3798 kg of sodium silicate (type Q - 28.9 wt% SKh, -8.9 wt% Na 2 - -62.2.2 wt% water) and 22.27 L - -water. Add 10.8 kg of a dispersant, which is a sodium salt of a polymerized substituted -benzenoid alkylsulfonic acid in a mixture of an inert organic solvent suspension (Daxad 27) and cool to about 13 ° C. . The acidic aluminum-containing solution is prepared by dissolving 137.25 kg of aluminum sulfate (17.2 percent Al 2 O 3), 330 kg of sulfuric acid (93 percent) and 170 kg of sodium chloride in -2287 liters of water. The solutions are mixed in a mixing nozzle and sprayed in the form of a gel with a stirrer equipped with a stirrer. While stirring, 540 kg of 'sodium chloride' are added to the gel and mixed thoroughly with the contents of the 'autoclave'. The resulting gel was vigorously stirred and heated to 93 ° C in a sealed container. After reducing the agitation intensity, an organic solution prepared by mixing -2.55.6 kg of tri-n-propylamine, 219.6 kg of nipropyl bromide and

The mixture is reacted for 14 hours at a temperature of 93-99 ° C. At the end of this period, the intensities of the stirring are increased and the conditions are maintained until the crystallinity of the product, as determined by X-ray diffraction, is maintained. It reaches at least -65 percent of ZSM-5. The temperature is then raised to 160 degrees Celsius and maintained at this value until crystallization is complete, and the remaining organics are removed from the autoclave and the product suspension is cooled.

The product was washed with a decanter using polyammonium bisulphate as a flocculating agent. The washed product containing less than 1% hydrogen was filtered and evaporated. The weight of the dried zeolite is about 10: 3) 5 kg. - The dried product - is mixed with the monohydrate - α-alumina and water (65% zeolite, 35% alumina, based on the annealed mixture) and - then extrudes - into pellets of - dimensions -1.6 mm, free-flowing weight <-0.98 g / cm3 and crush resistance> 3.6 kg / cm.

After drying, the extruded pellets are calcined in - nitrogen - (700 to 1003 - SCFM) for 3 hours at - 538 ° C, then - cooled - and - passed through the bed for 5 hours - - air. Then, the kattons are exchanged for the ions by one hour of treatment with 108 kg of sodium nitrate dissolved in 3040 ^{l of} deionized water at room temperature. The ion exchange is repeated and the pellets are washed and dried. The hydrogen concentration in the cation exchange pellets is less than 0.05% by weight.

The dried pellets are calcined in nitrogen-air - (10 to 12.5% air - 90 to 97.5 -% nitrogen) for 6 hours at 538 ° C and then cooled in nitrogen only. .....

The catalyst is used for - the disproportionation - of toluene, which is carried out by passing - through toluene - over 6.0 g of catalyst - by mass - at an hourly space velocity of 3.5 to 3.6 &lt; ^-1 &gt; C. The conditions and results are summarized in Table XIV.

Table XIV

Temperature Noc: 2 ° C Mass hourly space velocity '(h- ¹ ) Toluene conversion (mol%) 'Selectivity ·% % Of the β-isomer in xylene in the product benzene xylenes 450 3.6. 7.4. 43.5 55.5. 24.7. 500 3.5 20., 5 44.6 5.3,8 24.5 550 3.5 38.8 48.0 48.8 . 24,2 .. 600 3.5 49.2 54.4 41.7 , 24,1 '

216565

From the above results, it is clear that the unmodified catalyst provides a xylene product in which the β-isomer is present at its normal equilibrium concentration of about 24 wt. %, Based on the xylene fraction.

Example 82

To a solution of 8 g of 85% phosphoric acid (H 3 PO 4) in 10 ml of water was added 10 g of extruded HZSM-5, which was allowed to stand overnight at room temperature. After filtration and drying at 120 ° C for three hours, the product is calcined at 500 ° C for 3 hours to give 11.5 grams of ZSM-5, modified with 11.5 grams of phosphorus.

g of the phosphorus-modified ZSM-5 thus obtained is then added to a solution of 2 ^to 5 g of magnesium stannate tetrahydrate in 20 ml of water and the resulting mixture is allowed to stand overnight at room temperature. After filtration and drying at 120 ° C, the product is calcined at 500 ° C for 3 hours. 10.8 g of magnesium and phosphorus-modified ZSM-5 are obtained. The phosphorus concentration was determined to be 9.2% by weight. % and a magnesium concentration of 3.0 wt. %.

Example 83

Toluene is passed through 5 g of the catalyst of Example 82 at a hourly space velocity of 3.5 h @ ^-1 (based on the total catalyst) at 600 ° C. The toluene conversion is% and the p-xylene concentration in the total xylene mixture is 98.2%.

Example 8'4

Toluene is passed through 5 g of the catalyst of Example 82 with an hourly space velocity of 0.5 h ¹ (based on total catalyst) at 550 ° C. The toluene conversion is 39.5% and the p-xylene concentration in the total xylene mixture is 91.2%.

Example 85

The catalyst was prepared as described in Example 82 except that 7 g of 85% phosphoric acid (H 3 PO 4) was used. The weight of the resulting catalyst was 10.9 g. The following concentrations of modifying agents were found by analysis: phosphorus 7.4 wt. % magnesium

4.2 wt. %.

Example 86

Over 5 g of the catalyst of Example 85 is fed with toluene at a temperature of 3.5 ^{l / l} (based on the total catalyst) at a hourly hourly space velocity. The toluene conversion was 27.2% and the p-xylene concentration in the total xylene mixture was 96.6%.

When the experiment is repeated at different temperatures and space velocities, the following results are obtained:

Temperature ° C Weight Hour Conversion The concentration of p-xylene in the total xylene mixture space speed (h ¹ ) toluene 500 0.5 i32 85 400 0.16 21.9 93.6 300 0.08 8 88 2 250 0.08 4.3 92.8 203 0.08 2.2 95.7 Example 87 Example 88

To a solution of 3 g of 85% H 3 PO 4 in 12 mL of water was added 10 g of excreted HZSM-5, which was allowed to stand overnight at room temperature. The water was evaporated at 130 ° C with occasional stirring and then the product was dried at 200 ° C for 2 hours. It is obtained after calcination at 500 ° C

11.2 g of product. The analysis shows a phosphorus content of 7.5% by weight.

To a solution of 11 g of magnesium acetate Mgi (0Ac) 2.4 H2O in 20 ml of water was added 10 g of extruded phosphor modified ZSM-5, which was allowed to stand overnight at room temperature. The mixture was evaporated to dryness and then heated to 200 ° C. Calcination was carried out at 500 ° C for 2 hours. 11.3 g of magnesium and phosphorus-modified ZSM-5 are obtained. The analysis shows the following content of modifying agents: phosphOr 5.4 wt. % and magnesium 8.5 wt.%.

The toluene is passed through 5 g of the catalyst of Example 87 at a hourly space velocity of 3.5 h @ ^-1 (based on total catalyst) at 600 ° C. The toluene conversion is 18.2% and the p-xylene concentration in the total xylene mixture is 85.5%.

Example 1 a d 89

The toluene is passed through 5 g of the catalyst of Example 87 by a mass hourly space velocity of 0.4 h ^-1 at 550 ° C. The toluene conversion is 30.6% and the p-xylene concentration in the total xylene mixture is 40%.

Example 90

The general procedure of the example is repeated

82, to form a catalyst modified by magnesium and phosphorus ZSM-5. Analysis revealed the following content of modifiers: phosphorus 10.2 wt%. % and magnesium 4.7 wt.

Example _91:; Over 5 µg of the catalyst of Example 90 with a mass hourly space velocity; polish3.5 h ^-1 · (relative to total; catalyst) leads to toluene at 600 ° C. The toluene conversion is 21.8% and the concentration of p-xylene in the total xylene mixture is 65.2

Example. 32:

The toluene is passed through 5 g of catalyst according to Example 90 by a mass hourly space velocity of 0.4. h @ ¹ (based on total catalyst) at 550 ° C. The toluene conversion is 3.5% and the concentration of p-xylene in the total xylene mixture is 38.4%.

. It is apparent from the above results that high selectivity, to the β-isomer, is achieved by using the modified zeolites described in these floors as catalysts. Unmodified catalyst. provides under the same reaction. of the conditions specified in the preceding examples, p-xylene in an amount corresponding to the equilibrium content of p-xylene in the mixture of xylene isomers, 24%. . ’’

Claims (21)

CLAIMS 1. Catalyst for the selective production of p-dialkylbenzenes, characterized in that it consists of a crystalline aluminosilicate zeolite having an activity of 2 to 5000, a xylene sorption capacity of more than 1 g / 1.00 g of zeolite, for a period of time. xylene sorption for 30% of the above capacity greater than 10 minutes, the sorption capacity and sorption time measured at 120 ° C and 0.6 + 0.1 kPa pressure, S11O2 / / Al2O3 ratio 12 to 3000 and C-index in ranging from 1 to 12. 2. Catalyst according to claim 1, characterized in that at least part of the zeolite is present in the form of crystals of 0.5 to 20 .mu.m, preferably 1 to 6 .mu.m. and Catalyst according to Claims 1 and 2, characterized in that it contains carbonaceous deposits in an amount of 15 to 75, preferably 20 to 40% by weight, based on the catalyst without deposits. 4. Catalyst according to Claims 1 and 2, characterized in that the prescribed activity and sorption properties are achieved with zeolite which is perfectly mixed with 2 to 30% by weight, based on the weight of the zeolite, of one or more difficult-to-reduce hydrogen oxides. . Catalyst according to claim 4, characterized in that the hardly reducible oxide is an antimony, phosphorus, boron, uranium, magnesium, zinc and / or calcium oxide. 6. Catalyst according to claim 4 or 5, characterized in that the zeolite is admixed with 0.25 to 27% by weight of phosphorus oxide and magnesium oxide. 7. Catalyst according to claim 6, characterized in that the amount by weight of phosphorus oxide is preferably 0.7 to 15 and the amount by weight of magnesium oxide is 1 to 15%. 8. The catalyst of claim 1 wherein the interior of the zeolite crystalline structure contains 0.1-10% by weight of the zeolite added amorphous silica. 9. The catalyst of claim 8 wherein the silica fraction is from about 2% to about 10% by weight. Catalyst according to claim 8 or 9, characterized in that the silica is a degradation product of a silicon compound capable of entering the pores of the zeolite, VYNALEZU 11. The catalyst of claim 1, wherein the silicon compound is a silicone, a siloxane or a polysilane, or a monomethyl, inunochlor, or menofluorivative thereof. 12. The catalyst of claim 10 wherein the silicon compounds have the general formula S1R1R2R3R4 wherein each represents a symbol R1 and R2 are hydrogen, fluoro, chloro, methyl, ethyl, amino, meithoxy or ethoxy, R 3 is hydrogen, fluoro, chloro, methyl or amino; R 4 is hydrogen or fluoro. 113. The catalyst of claim 10 wherein the silicon compound is silane, di methylsilane ^1, dichlorosilane, or silicon tetrafluoride methylsiian. 1’4. 2. A catalyst as claimed in claim 1 wherein a coating of silica in an amount of from 0.5 to 30% by weight, based on the zeolite, is provided on the outer surface of the zeolite. 15. The catalyst of claim 11 wherein the silica is a decomposition product of a silicon compound that cannot enter the zeolite pores. 16. The catalyst of claim 15 wherein the silicon compound has the general formula Sí.o3- _n wherein each R IRI and R2, which are identical or different, represent fluoro, hydroxy, alkyl, aralkyl, alkylaryl or fluoroalkyl and In addition, R 1 can also represent hydrogen, n is an integer of 10 to 1000, wherein 2 18 5 64 R1 or R2 contains 1 to 10 carbon atoms. 17. Catalyst according to claim 15 or 16, characterized in that:. the silicon compound has a molecular weight of 500 to 20,000, preferably 1000 to 10,000. 18th Catalyst according to claim 15 .When 17 vy- labeled by • the silicon compound is dimethyl-hhlsilloxan, dlethylsiloxan, fenylmethylsítoxan, methyl hydrogen, ethylhydrogensiloxan, fenylhydrogensiloxan, .methýlethylsiloxan, fenylethylsiloxan, diphenylsiloxane, methyltrlflu ^ι · ropylsiloxan CRP, ethyltrifluorpropylsHoxan, poiydimethyteUoxan , tetrachlorophenylmiethylsulfoxane, tetrachlorophenylphenylstloxane, tetraichlorophenylhydroxysiloxane, tetrachlorophenylphenylsiloxane, methylvinylsiloxane and ethylvinylsiloxane. Catalyst according to Claims 1 to 18, characterized in that the zeolite comprises zeolite ZSM-5, ZSM-11, ZSM-12, ZSM-35 or ZSM-31. ; 20. A catalyst according to any one of claims 1 to 19, wherein the zeolite comprises hydrogen cations. Catalyst according to Claims 1 to 20, characterized in that the zeolite has an activity in the range of. · 5 to 200. 22. Catalyst according to points. 1 to 21, characterized in that it consists of a mixture of the above-defined zeolite with a binder, the binder content in the mixture being 1 to 99, preferably 20 to 95% by weight, preferably 30 to 40% by weight. 23. The catalyst of claim 22 wherein the binder is a naturally occurring or synthetic refractory oxide. 24. The catalyst of claim 23 wherein the naturally occurring oxide is montmorillonite or kaolin clay, and the synthetic oxide is silica, alumina, magnesium oxide, oxide, zirconia, thorium oxide. beryllium oxide and / or titanium dioxide.