KR100277545B1 - Form Selective Conversion Catalyst - Google Patents

Abstract

The present invention relates to a form-selective conversion catalyst which is treated with a mixture of a selector and toluene at reaction conditions for converting toluene to xylene and contains molecular sieves having a Constraint Index of 1 to 30.

Description

Form Selective Conversion Catalyst

The present invention relates to a catalyst for morphologically selective conversion, such as the conversion of toluene to para-xylene.

The term form selective catalysis refers to unexpected catalytic selectivity in zeolites. The principle for form-selective catalysis is, for example, n. Why. N. Y. Chen, W. this. W. E. Garwood and F. rat. It has been extensively re-studied by F. G. Dwyer (see "Shape Selective Catalysis in Industrial Applications," 36, Marcel Dekker, Inc.). (1989). In zeolite pores, hydrocarbon conversion reactions such as paraffin isomerization, olefin backbone or double bond isomerization, oligomerization and aromatic disproportionation, alkylation or transalkylation reactions are affected by channel size. Reactant selectivity occurs when the feedstock components are so large that they do not flow into the zeolite pores where the reaction occurs; Product selectivity, in contrast, occurs when some of the product cannot exit the zeolite channel. The product distribution can also be varied by the transition state selectivity at which a particular reaction cannot occur because the reaction transition state is too large to form in the zeolite pores or cages. Another form of selectivity arises due to structural diffusion when the size of the molecules is close to that of the zeolite pore system. Even small changes in zeolite pore or molecular size can lead to significant diffusion and vary product distribution. This type of form-selective catalysis is evidenced by the reaction of selective disproportionation with, for example, toluene p-xylene.

Para-xylene is a very valuable industrial product useful for the production of polyester fibers. The catalytic preparation of para-xylene has received very great scientific attention, and many methods are known for increasing para-selectivity by catalyst.

The synthesis of para-xylene is generally carried out by methylation of toluene in the presence of a suitable catalyst. Such examples are described by Chen et al. Amer. Chem. Sec. Reaction of toluene and methanol as described in 1979, 101, 6783, and by Pines, "The Chemistry of Catalytic Hydrocarbon Conversions", Academic Press, N.Y., 1981, p. 72, there is a toluene disproportionation reaction as described. This method generally produces a mixture comprising para-xylene, ortho-xylene and meta-xylene. Depending on the reaction conditions and the para-selectivity of the catalyst, different proportions of para-xylene are obtained. The yield, ie the amount of feedstock actually converted to xylene, is also influenced by the catalyst and reaction conditions.

The equilibrium reaction in which toluene is disproportionate to xylene and benzene proceeds as follows:

One known method of increasing the para-selectivity of zeolite catalysts is to modify the catalyst by treating it with a "selective agent." A reforming method has been proposed that treats the catalyst before use to provide a silica coating. For example, US Pat. Nos. 4,477,583 and 4,127,616 describe methods for contacting a catalyst with a modifying compound such as phenylmethyl silicone in a hydrocarbon solvent or an aqueous emulsion at ambient temperature, followed by calcination. This reforming method has been successful in obtaining para-selectivity of up to about 90%, but is not commercially available because only about 10% of toluene is converted so that the yield does not exceed about 9% (ie, 10% x 90%). . This method also requires costly separation processes such as fractional crystallization and adsorptive separation to separate para-xylene from isomers other than para-xylene by forming significant amounts of ortho-xylene and meta-xylene. Isomers other than para-xylene are usually recycled, requiring a xylene isomerization unit to further convert the recycled xylene isomer into an equilibrium xylene mixture containing para-xylene.

Those skilled in the art recognize that the cost of the separation process is proportional to the degree of separation required. Thus, increasing the selectivity to para-isomers while maintaining the conversion rate at a commercial level can save significant costs.

Another conversion process that can benefit from the type selectivity of the catalyst used is dewaxing of the hydrocarbon feedstock; Isomerization of alkyl aromatic compounds; Oligomerizing olefins to form gasoline, distillate, lubricating oil or chemicals; Alkylation of aromatic compounds; Conversion of oxygenate to hydrocarbons; Rearrangement of oxygenates; And conversion of light paraffins and olefins to aromatic compounds.

It is therefore an object of the present invention to provide an improved selective conversion catalyst.

Accordingly, the present invention relates to a morphologically selective conversion catalyst which is treated with a mixture of a selector and toluene under reaction conditions for converting toluene to xylene and contains molecular sieves having a Constraint Index of 1 to 30.

The molecular sieve catalyst used in the process of the present invention preferably has an initial limit index value of 1 to 30, preferably 1 to 20, more preferably 1 to 12, preferably ZSM-5, ZSM-11, Medium pore size zeolites such as ZSM-22, ZSM-23 or ZSM-35, most preferably ZSM-5 are included. The catalyst preferably has an alpha value of greater than 100, for example an alpha value of 150 to 2000, and the silica-alumina ratio is less than 100, preferably 20 to 80. The alpha value of the catalyst can be increased by treating the catalyst with nitric acid or by gently steaming as described in US Pat. No. 4,326,994.

The alpha value is an approximate indicator of the catalytic cracking activity of the catalyst obtained in comparison with the standard catalyst, which gives a relative rate constant (rate of conversion of n-hexane per unit volume of catalyst). This is based on the activity of the amorphous silica-alumina decomposition catalyst and its alpha value is 1 (rate constant = 0.016 sec ^-1 ). Alpha tests used in the present invention are described in US Pat. No. 3,354,078 and in The Journal of Catalysis, Vol. 4, pp. 522-529 (Augu st 1965): Vol. 6, p. 278 (1966); And Vol. 61, p. 395 (1980). The intrinsic rate constants of most acid-catalyzed reactions are proportional to the alpha value of certain crystalline silicate catalysts (see, eg, "The Active Site of Acidic Aluminosilicate catalysts," Nature, Vol. 309, No 5959, pp 589-). 591, 14 June 1984). The experimental conditions of the test used herein are constant temperature of 538 ° C. and Journal of Catalysis, Vol. 61, p. 395, variable flow rate described in detail. The limiting index and its measuring method are described in US Pat. No. 4,016,218.

The molecular sieve catalyst used in the process of the invention can be used in combination with a support or binding material, for example a porous inorganic oxide support or a clay binder. Preferred binders are mainly silica. Examples of other non-limiting binding materials include alumina, zirconia, magnesia, toria, titania, boria, and combinations thereof, generally in the form of dried inorganic oxide gels or gelatinous precipitates. Suitable clay materials include, for example, bentonite and kieselguhr. The relative ratio of suitable crystalline molecular sieves to the total composition of the catalyst and the binder or support may be 30 to 90% by weight, preferably 50 to 80% of the composition. The composition may be in the form of extrudates, beads or fluidizable microspheres.

The molecular sieve catalyst is provided with the required form selectivity by treatment with a mixture of selector and toluene under conditions sufficient to disproportionate toluene to xylene (hereinafter referred to as "trim-selection"). . The selector is supplied in an amount of 0.1 to 50% by weight, preferably 0.1 to 20% by weight of toluene. The trim-selective agent is preferably a volatile organosilicon compound, and the reaction conditions are conveniently between 100 ° C. and 600 ° C., preferably between 300 ° C. and 500 ° C., with a pressure between 100 and 14000 kPa (0 and 2000 psig). , Preferably 200 to 5600 kPa (15 to 800 psig); The molar ratio of hydrogen to hydrocarbon is from 0 (ie no hydrogen present) to 10, preferably 1 to 4; The visual weight space velocity (WHSV) is between 0.1 and 100, preferably between 0.1 and 10. The trim-selection reaction preferably takes place in the same vessel as the reaction vessel used for the catalyzed conversion reaction and preferably lasts for 50 to 300 hours, most preferably less than 170 hours. Upon pyrolysis, siliceous coatings are deposited on the zeolite surface to improve shape-selectivity by reducing or eliminating zeolite surface activity.

Preferably, prior to trim selectivity, the molecular sieve catalyst is pretreated in another vessel with a selector in the form of a silicon-containing compound (hereinafter referred to as "pre-selection"). In the case of pre-selection, the silicon compound is deposited on the outer surface of the catalyst by any suitable method. For example, the silicon compound may be dissolved in a solvent, mixed with a catalyst and then dried. The silicon compound used may be in solution, liquid or gas form under contact conditions with the zeolite. Examples of methods for depositing silicon on zeolite surfaces are described in US Pat. Nos. 4,090,981, 4,127,616, 4,465,886, and 4,477,583.

The catalyst is preferably calcined after depositing the silicon-containing compound in the pre-selection. For example, the catalyst can be calcined under an oxygen-containing atmosphere, preferably in air, to a temperature above 300 ° C. at a heating rate of 0.2 ° C. to 5 ° C. per minute, but to a temperature that does not adversely affect the crystallinity of the zeolite. . Generally, the temperature which does not adversely affect the crystallinity of zeolite is 600 degrees C or less. Preferably the calcination temperature is in the range of about 350 ° C to 550 ° C. The product is maintained at calcination temperature for 1 to 24 hours in general.

It has been found that preselective of the catalyst can reduce the amount and time of selector required to trim-select the catalyst.

Silicon compounds used for pre-selection and / or trim-selection may include polysiloxanes containing silicon, siloxanes, and silanes containing disilanes and alkoxysilanes.

Silicone compounds that can be used in the present invention can be characterized by the following general formula:

Where

R ₁ is hydrogen, fluorine, hydroxy, alkyl, aralkyl, alkaryl or fluoro-alkyl. Hydrocarbon substituents generally contain 1 to 10 carbon atoms and are preferably methyl or ethyl groups. R ₂ is selected from the same group as R ₁ and n is an integer of at least 2, generally 2 to 1000. The molecular weight of the silicone compound used is generally 80 to 20,000 and preferably 150 to 10,000. Examples of representative silicone compounds include dimethylsilicone, diethylsilicone, phenylmethylsilicone, methylhydrogensilicone, ethylhydrogensilicone, phenylhydrogensilicone, methylethylsilicon, phenylethylsilicone, diphenylsilicone, methyltrifluoropropylsilicone , Ethyltrifluoropropylsilicone, tetrachlorophenylmethyl silicone, tetrachlorophenylethyl silicone, tetrachlorophenylhydrogen silicone, tetrachlorophenylphenyl silicone, methylvinylsilicon and ethylvinylsilicon. The silicone compound need not be linear, but may be cyclic, such as, for example, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, and octaphenylcyclotetrasiloxane. Mixtures of these compounds can also be used as silicones with other functional groups.

Useful siloxanes or polysiloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, hexaethylcyclo Trisiloxane, octaethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, and octaphenyl-cyclotetrasiloxane, including but not limited to these.

Useful silanes, disilanes or alkoxysilanes include organic substituted silanes having the following general formula:

In the above formula,

R is a reactive group such as hydrogen, alkoxy, halogen, carboxy, amino, acetamide, trialkylsilyl. R ₁ , R ₂ , and R ₃ may be the same as R, or an alkyl moiety of 1 to 40 carbon atoms, an organic moiety of alkyl containing 1 to 30 carbon atoms, and an aryl group containing 6 to 24 carbon atoms It may be an organic radical which may contain alkyl or aryl carboxylic acids containing, aryl groups having 6 to 24 carbon atoms which may be further substituted, alkylaryl and arylalkyl groups having 7 to 30 carbon atoms. Preferably, the alkyl group of the alkyl silane has 1 to 4 carbon atoms in the main chain. Mixtures may also be used.

Examples of silanes or disilanes include, but are not limited to, dimethylphenylsilane, phenyltrimethylsilane, triethylsilane and hexamethyldisilane. Useful alkoxysilanes are those having at least one silicon-hydrogen bond.

Theoretically limited, it is believed that the advantage of the present invention is obtained by applying an acid moiety to the outer surface of the catalyst which is not actually accessible to the reactants while increasing the catalyst distortion. It is believed that the acid sites present on the outer surface of the catalyst isomerize para-xylene exiting the catalyst pores and remain in equilibrium with the other two isomers to reduce the amount of para-xylene in xylene to about 24%. The amount of para-xylene can be maintained at a relatively high level by reducing the extent of the acid site acting on the para-xylene exiting the catalyst pores. Selective agents of the present invention block the acid sites present on the outer surface or chemically modify them so that these acid sites do not have access to para-xylene.

Preferably, the diameter of the selector should be larger than the diameter of the zeolite pores to prevent the internal activity of the catalyst from decreasing.

In addition, the presence of hydrogen in the reaction zone is believed to be important when using silicone compounds as trim-selecting agents.

Selected catalysts of the present invention include hydrocarbon cracking under reaction conditions including temperatures of 300 ° C. to 700 ° C., pressures of from 10 to 3000 kPa (0.1 to 30 atmospheres), and an initial weight space velocity of 0.1 to 20; Dehydration of the hydrocarbon compound under reaction conditions including a temperature of 300 ° C. to 700 ° C., a pressure of 10 to 1000 kPa (0.1 to 10 atmospheres) and a weight hourly space velocity of 0.1 to 20; Converting paraffins to aromatics under reaction conditions including temperatures of 300 ° C. to 700 ° C., pressures of from 10 to 6000 kPa (0.1 to 60 atm), hourly space velocity of 0.5 to 400 and molar ratios of hydrogen / hydrocarbon of 0 to 20 reaction; The olefin may be converted into an aromatic compound, for example, under reaction conditions including a temperature of 100 ° C. to 700 ° C., a pressure of 10 to 6000 kPa (0.1 to 60 atm), an hourly weight space velocity of 0.5 to 400 and a mole ratio of hydrogen / hydrocarbon of 0 to 20. Reactions such as conversion to benzene, toluene and xylene; Alcohols, for example methanol or ethers, for example dimethyl ether, or under reaction conditions including temperatures from 275 ° C. to 600 ° C., pressures from 50 to 5000 kPa (0.5 to 50 atm) and hourly space velocity from 0.5 to 100; Reaction of converting a mixture thereof into a hydrocarbon; Isomerize the xylene feedstock component under reaction conditions including a temperature of 230 ° C. to 510 ° C., a pressure of 300 to 3500 kPa (3 to 35 atmospheres), an hourly weight space velocity of 0.1 to 200, and a hydrogen / hydrocarbon molar ratio of 0 to 100. Reaction; Toluene disproportionation under reaction conditions including a temperature of 200 ° C. to 760 ° C., a pressure of 100 to 6000 kPa (atmospheric pressure to 60 atm) and a weight hourly space velocity of 0.08 to 20; Alkylating agents under reaction conditions including temperatures from 250 ° C. to 500 ° C., pressures from 100 to 20000 kPa (atmospheric to 200 atmospheres), time weight space velocities from 2 to 2000 and molar ratios of aromatic hydrocarbons / alkylating agents from 1/1 to 20/1, Reactions for alkylating aromatic hydrocarbons such as benzene and alkylbenzenes, for example in the presence of olefins, formaldehyde, alkyl halides and alcohols; And a reaction comprising a temperature of 340 ° C. to 500 ° C., a pressure of 100 to 20000 kPa (atmospheric to 200 atmospheres), a time weight space velocity of 10 to 1000 and an aromatic hydrocarbon / polyalkylaromatic hydrocarbon mole ratio of 1/1 to 16/1. Suitable for use in various morphologically selective hydrocarbon conversion reactions include, but are not limited to, transalkylation of aromatic hydrocarbons in the presence of polyalkyl aromatic hydrocarbons under conditions.

Thus, generally, catalytic conversion conditions for the modified zeolite catalysts of the present invention include temperatures of 100 ° C. to 760 ° C., pressures of 10 to 20000 kPa (0.1 to 200 atmospheres), time weight space velocities of 0.08 to 2000, and zero Hydrogen to organic compounds, such as hydrocarbon compound ratios, from 100 to 100 are included.

The modified catalyst of the present invention is also advantageously used for the synthesis of pyridine. Pyridine bases can be prepared by the reaction of aldehydes and ketones with ammonia. Reacting the aldehyde with ammonia in the presence of a heterogeneous catalyst at 350 ° C. to 550 ° C. produces 2- and 4-methylpyridine. Acetaldehyde, formaldehyde and ammonia react to form pyridine and 3-methylpyridine. Pyridine synthesis is described, for example, in US Pat. No. 4,675,410 by Feitler and US Pat. No. 4,220,783 by Chang et al.

Selected catalysts of the present invention are also used in the synthesis of caprolactam used in the industrial production of nylon. Caprolactam can be prepared by Beckman rearrangement of cyclohexane oxime using an acid catalyst including zeolite. The synthesis of caprolactam is described, for example, in US Pat. No. 4,359,421.

The catalyst of the present invention is particularly useful for disproportionating toluene to para-xylene. For example, the purity of para-xylene is at least 90%, preferably at least based on the total C ₈ product, while maintaining toluene conversion at least 15%, preferably at least 20%, and most preferably at least 25%. 95% can be achieved. Furthermore, the ortho-xylene isomers can be reduced to about 0.5% or less of the total xylene content, and the meta-xylene isomers can be reduced to less than about 5% of the total xylene content. In addition, proper treatment of the reaction system, such as by depositing platinum on molecular sieves, can significantly reduce the amount of ethylbenzene present, for example less than about 2% of the C ₈ product.

Operational conditions for the toluene disproportionation method of the present invention include 350 to 540 ° C., preferably 400 ° C. or higher, 100 to 35000 kPa (atmospheric pressure to 5000 psig), preferably 800 to 7000 kPa (100 to 1000 psig). Pressures of 0.1 to 20, preferably 2 to 4, and hydrogen to hydrocarbon molar ratios of 0.1 to 20, preferably 2 to 4, inclusive. The disproportionation method of the present invention can be carried out in a fixed bed or fluidized bed mode where the side benefits can be easily obtained.

The eluate is separated and distilled to separate the desired product, para-xylene and other by-products. The unreacted reactant, ie toluene, is preferably recycled to further reaction. Benzene is a useful coproduct.

According to a preferred embodiment of the present invention, when used for disproportionation of toluene, the catalyst is further modified to reduce the amount of undesirable by-products, especially ethylbenzene. The reactor eluate produced by toluene disproportionation according to the method of the art generally contains about 0.5% ethylbenzene byproduct. Distillation of the reaction product increases the amount of ethylbenzene in the C ₈ fraction to 3-4%. This amount of ethylbenzene is unsuitable for polymer grade p-xylene because, if not removed, ethylbenzene in the C ₈ product will degrade the fiber made from the p-xylene product. Therefore, the content of ethylbenzene should be kept at a low level. It is determined that the standard amount of ethylbenzene in the C ₈ product should be less than 0.3% industrially. Ethylbenzene can be substantially removed by isomerization or superfractionation. Removal of ethylbenzene by conventional isomerization results in the present invention because at least 90% isomerizes the xylene stream consisting of para-xylene to equilibrium xylene to reduce the amount of para-xylene in the xylene stream to about 24%. Not available. In addition, another method of removing ethylbenzene by fractional distillation is very expensive.

In order to eliminate the need to remove the downstream ethylbenzene, it is advantageous to reduce the amount of ethylbenzene by-product by adding a metal compound such as platinum to provide the hydrogenation-dehydrogenation functionality to the catalyst. Platinum is the preferred metal, but other metals can be used, such as palladium, nickel, copper, cobalt, molybdenum, rhodium, ruthenium, silver, gold, mercury, osmium, iron, zinc, cadmium, and mixtures thereof. The metal may be added by cation exchange in an amount of 0.01 to 2%, generally about 0.5%. The metal enters the pores of the catalyst and is present in the subsequent calcination step. For example, a platinum modified catalyst can be prepared by first adding ammonium nitrate solution to the catalyst to convert the catalyst into ammonium form, and then adding an aqueous solution of tetraamine platinum 11 to increase the activity. The catalyst is then filtered off, washed with water and then calcined at a temperature of 250 ° C to 500 ° C.

The invention is described in more detail with reference to examples and the accompanying drawings:

FIG. 1 is a graph comparing xylene para-selectivity and toluene conversion for silicon trim-selected ZSM-5 catalysts in the presence of hydrogen (Example 1) or nitrogen as a function of stream time.

FIG. 2 is a graph similar to that of FIG. 1 showing the results when co-feeding hydrogen at somewhat lower temperatures used in Example 2. FIG.

FIG. 3 also shows a result obtained in a graph similar to that of FIG. 1, without a common supply of hydrogen (Example 3).

4 is a graph showing para-xylene and toluene conversion as a function of time for the stream.

5 shows para-selectivity and conversion for zeolites preselected with 10% SiO ₂ .

6 shows para-selectivity and conversion for zeolites preselected with 5% SiO ₂ .

Toluene disproportionation is carried out in a fixed bed reactor using 2 g of silica bonded HZSM-5 catalyst having a silica / alumina ratio of 26, a crystal size of 0.1 micron, and an alpha value of 731. Toluene is fed to the reactor containing 1% of a silicone compound having a phenylmethyl silicone to dimethyl silicone ratio of 1: 1. Operating conditions were WHSV 4.0, temperature 480 ° C., pressure 3550 kPa (500 psig), and hydrogen / hydrocarbon ratio 2. Table 1 below shows toluene conversion and para-xylene selectivity as a function of time for trim-selection and subsequent streams.

TABLE 1

* Stop supplying silicone joints.

It is noteworthy that silicon trim-selection increases para-xylene selectivity substantially from the initial 22% to over 90%. The feed was switched to 100% toluene at 174 hours for the stream, ie the silicon co-feed was stopped. Over a week of testing, the toluene conversion was constant at 25% and para-xylene selectivity was constant at 91%.

The above-mentioned results are shown in FIG. 1, which also shows the results of the selection carried out in the presence of nitrogen other than hydrogen. In the presence of nitrogen, the catalyst is rapidly deactivated and the conversion rate approaches zero very quickly.

Example 2

The toluene disproportionation method of Example 1 is repeated at WHSV 4.0, temperature 446 ° C., pressure 3550 kPa (500 psig), and hydrogen / hydrocarbon ratio 2. Table 2 below shows toluene conversion and para-xylene selectivity as a function of time for the stream.

TABLE 2

* Stop supplying silicone joints.

Silicon trim-selection increases para-xylene selectivity from 24% (thermodynamic value) to 97% (toluene conversion 25%) or more. Para-xylene selectivity and toluene conversion did not change to 97% and 25%, respectively, when the silicon co-feed was stopped. The results are shown in FIG.

Example 3

The toluene disproportionation method of Example 1 is repeated at WHSV 4.0, temperature 420 ° C., pressure 100 kPa (0 psig), and hydrogen / hydrocarbon ratio 0. Table 3 and Figure 3 below show toluene conversion and para-xylene selectivity as a function of time for the stream. When performed in the presence of hydrogen, the conversion is stabilized to 25% at 184 hours for the stream, while in this example the conversion actually drops to zero at 184 hours for the stream.

TABLE 3

Example 4

Toluene disproportionation is carried out on SiO ₂ -HZSM-5 using 1% octamethylcyclotetrasiloxane in the toluene feed as trim-selective agent. The operating conditions are temperature 446 ° C., pressure 3550 kPa (500 psig), WHSV 4.0, and H ₂ / CH ratio 2. The results are shown in Table 4 below.

TABLE 4

Example 5

Toluene disproportionation is performed by trim-selection as in Example 4 using hexamethyldisiloxane (HMDS). The results are shown in Table 5 and FIG. 4 below.

TABLE 5

4 shows high p-xylene selectivity and toluene conversion over 350 hours applied to the stream. Toluene conversion remained at about 18-20% while maintaining the p-xylene selectivity at 99% for the duration of time. After about 50 hours HMDS was stopped.

[Examples 6 to 14]

The method of Example 4 is repeated with trim-selection using the siloxanes described in Table 6. The operating conditions are temperature 446 ° C., pressure 3550 kPa (500 psig), WHSV 4.0, and H ₂ / CH ratio 2. The results after 24 hours are shown in Table 6 below.

TABLE 6

^a —Continuing selectivity under the above quoted time achieves p-xylene selectivity above 90% while maintaining toluene conversion at least 15%.

[Examples 15 to 19]

The trim-selection of Examples 4 and 5 is repeated using the silanes listed in Table 7. The operating conditions are temperature 446 ° C., pressure 3550 kPa (500 psig), WHSV 4.0, and H ₂ / CH ratio 2. The results after 24 hours are shown in Table 7 below.

TABLE 7

Continued selectivity under ^a -24 hours achieves p-xylene selectivity above 90%.

[Examples 20 to 24]

For comparison, the compounds described in Table 8 were tested as in Examples 6-19 and the results are shown in Table 8.

TABLE 8

Example 25

Silica pre-selective ZSM-5 catalyst was prepared by adding 5.00 g of HZSM-5 to 1.26 g of phenylmethylpolysiloxane in 40 cc of hexane. The solvent is distilled off and the catalyst is air calcined at 1 ° C./min to 538 ° C. and then at 538 ° C. for 6 hours. The pre-selected catalyst contains 10% added silica.

Silicon trim selectivity of 10% SiO ₂ -HZSM-5 is performed at a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4.0, and a hydrogen / hydrocarbon ratio of 2. Table 9 and Figure 5 below show toluene conversion and para-xylene selectivity for 10% SiO ₂ -HZSM-5 as a function of time for the stream.

Table 9 Silicon Selectivity of 10% S: O ₂ -HZSM-5

Silicon trim selectivity actually increases para-xylene selectivity from 33% to 98% over the 28 hours applied to the stream. The feed was then changed to 100% toluene. After 10 hours, the selectivity increased to 99% while the conversion remained at 16%. To further increase the conversion, the temperature is increased to 457 ° C. and then immediately increased to 468 ° C. After the conversion rate has risen to 21%, it is slightly reduced to 20% over the next 80 hours. Para-xylene selectivity increases from 99.2% to 99.6% during the above 80 hours.

Compared to the HZSM-5 of Example 1, the 10% SiO ₂ -HZSM-5 (pre-selected) catalyst of Example 25 actually shows higher selectivity. In the case of pre-selected HZSM-5, 89% para-xylene selectivity is achieved after application for only 10 hours (17 times faster than 170 hours for the parent HZSM-5) for the stream. In addition, the time required to reach optimal para-selection is one week for HZSM-5, whereas HZSM-5 for pre-selected is one day, with higher selectivity temperatures for HZSM-5 (480 ° C vs. 446 ° C). Nevertheless, the time required to reach optimal para-selection of pre-selected HZSM-5 is shorter than the time required to reach optimal para-selection of HZSM-5.

The total consumption of phenylmethyl silicone is 6.80 grams of silicon per gram of HZSM-5 and 1.42 grams of silicon per gram of HZSM-5 pre-selected. Thus, trim-selection of the pre-selected HZSM-5 consumes almost five times (4.79 times) less silicon than without the catalyst pre-selection.

Example 26

The procedure of Example 25 is repeated except that the pre-selected catalyst contains only 5% added silica. Tables 10 and 6 below show the para-xylene selectivity and toluene conversion for the 5% SiO ₂ -HZSM-5 catalyst as a function of time for the stream.

TABLE 10

Silicon trim-selection actually increases para-xylene selectivity from 25% to 98% for 26 hours for the stream. Compared with 10% SiO ₂ -HZSM-5, the 5% SiO ₂ catalysts show higher conversions at all times during the day's selectivity time. The feed is then changed to 100% toluene. During the next 6 hours, the selectivity increased to 99% with a conversion of 24%, the temperature increased to 468 ° C, and the WHSV decreased to 3. The conversion rate increases to 27% and then gradually decreases to remain constant at 21% for 6 days (146 hours). Correspondingly, para-xylene selectivity did not initially vary from 99% and then gradually increased to remain constant from 99.6 to 99.9% for 6 days when randomly stopped running.

Example 27

0.05% Pt-10% SiO ₂ -HZSM-5 catalyst was prepared by adding 2.50 g of 10% SiO ₂ -HZSM-5 prepared in Example 25 to 12.5 cc of 1 M ammonium nitrate solution. After 1.5 hours, a solution of 0.0025 g of tetraamine platinum nitrate (II) in about 0.5 cc water is added. After standing overnight, the catalyst is filtered off, washed with water, air and calcined at 350C at 5C / min and then at 350C for 3 hours.

Toluene disproportionation is carried out using 2.00 g of the resulting catalyst at a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4, and a hydrogen / hydrocarbon molar ratio of 2. Table 11 below shows the product distributions compared to silica-modified HZSM-5 containing no Pt prepared in Example 25 tested under the same operating conditions. At similar toluene conversion, the ethylbenzene product when using the Pt-catalyst was reduced by nearly 12 times. Unnecessary C ₉ ⁺ aromatics product was also reduced by nearly a factor of two.

TABLE 11

Example 28

The catalyst of Example 27 was treated in a single vessel using a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4, and a 1% solution of phenylmethylpolysiloxane in toluene at a hydrogen / hydrocarbon molar ratio of 2 do. After 32 hours for the stream, the feed is changed to 100% toluene. Table 12 below shows the product distributions compared to silica-modified HZSM-5 treated with siloxane and tested without Pt under the same operating conditions.

TABLE 12

At similar toluene conversions, the ethylbenzene product when using the Pt-catalyst was reduced by almost 3.6-fold, with the p-xylene selectivity being very high, from 98.4% to 98.7%. Unnecessary C ₉ ⁺ aromatics product was also reduced by nearly three-fold.

The results of Examples 29-31 described in Table 13 show that the addition of platinum to the catalyst molecular sieve provides a beneficial effect on ethylbenzene in the product stream.

Example 29

Silicon trim-selection of 10% SiO ₂ -HZSM-5 using a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4.0, and a 1% solution of phenylmethyl silicon in toluene at a hydrogen / hydrocarbon ratio 2 Perform anger. At 31 hours for the stream, the feed is changed to 100% toluene. The temperature is increased to 468 ° C. at 52 hours for the stream and the WHSV is reduced to 3.0 at 165 hours. Data for day 39 for the stream is shown in the first column of Table 13.

Example 30

Silicon of 0.025% Pt 10% SiO ₂ -HZSM-5 using a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4.0, and a 1% phenylmethyl silicon feed in toluene at a hydrogen / hydrocarbon ratio of 2 Perform the selection. At 56 hours for the stream, the feed is changed to 100% toluene. The temperature is increased to 468 ° C. at 73 hours for the stream. Data for day 7 for the stream is shown in the second column of Table 13.

Example 31

Nitric acid activated 0.05% Pt 10% SiO ₂ -HZSM- using a 1% phenylmethyl silicone feed in toluene at a temperature of 446 ° C., a pressure of 3550 kPa (500 psig), a WHSV of 4.0, and a hydrogen / hydrocarbon ratio of 2 Perform silicon selectivity of 5. At 27 hours for the stream, the feed is changed to 100% toluene. The temperature, WHSV, and hydrogen / hydrocarbon ratio are changed during the run. Data for day 13 for the stream is shown in the third column of Table 13.

TABLE 13

Examples 29-31 suggest that the use of catalyst molecular sieves having hydrogenation / dehydrogenation functional groups such as platinum incorporated into the catalyst molecular sieves can reduce the amount of ethylbenzene in the reaction products of the present invention. The amount of ethylbenzene in the product stream is preferably at an industrially acceptable level of 0.3% or less, most preferably about 0.2% or less.

As mentioned above, the present invention advantageously provides a product stream with high para-xylene purity for other C ₈ products. Table 14 provides the relative ratios of para-xylene to the combinations of the different products.

TABLE 14

Example 32

446 using 1.0 g trim-selected SiO ₂ -HZSM-5 catalyst with 1% phenylmethyl silicon feed in toluene at a temperature of 446 ° C., a pressure of 500 psig, a WHSV of 4 and a H ₂ / HC ratio 2 Toluene alkylation is carried out with ethylene at a temperature of 占 폚 and a pressure of 800 kPa (100 psig). Toluene is pumped to 4 WHSV. Ethylene and hydrogen are fed together to maintain the molar ratio of toluene / ethylene / hydrogen at 8/1/3. At 10% toluene conversion (80% for the theoretical maximum conversion of 12.5%), the selectivity for p-ethylenetoluene was very high at 99.1%, while the selectivity for m-ethyltoluene was only 0.9%.

Example 33

Toluene alkylation is carried out with methanol at a temperature of 446 ° C. and a pressure of 3550 kPa (500 psig) using 2.00 g of trim-selected SiO ₂ -HZSM-5 catalyst as mentioned above. Toluene is pumped to 4 WHSV. Methanol and hydrogen are fed together to maintain the molar ratio of toluene / methanol / hydrogen at 4/1/8. At 14% toluene conversion (56% for 25% theoretical peak conversion), the selectivity for p-xylene is very high at 99.9%, while the selectivity for m-xylene is only 0.1%.

Example 34

2.00 g of trim-selected SiO ₂ -HZSM-5 catalyst as mentioned above were used to carry out the conversion reaction of n-heptane at a temperature of 446 ° C., a pressure of 100 kPa (0 psig) and a WHSV of 4. The distribution of aromatic products at heptane conversion of 21% is shown in the table below. The p-xylene selectivity in the xylene fraction is very high at 99.3% while the m-xylene selectivity is only 0.7%.

Example 35

As mentioned above, 1.00 g of trim-selected SiO ₂ -HZSM-5 catalyst was used to carry out the conversion of methanol at a temperature of 371 ° C., a pressure of 100 kPa (0 psig) and a WHSV of 1. The distribution of the liquid product at 100% methanol conversion is shown in the table below.

Example 36

Fries displacement reaction of phenylacetate was carried out using a trim-selected SiO ₂ -HZSM-5 catalyst as mentioned above at a temperature of 400 ° C., a pressure of 800 kPa (100 psig) and a WHSV of 1 . The 4-hydroxyaceto-phenone product is obtained with high selectivity.

Example 37

Propylene oligomerization is carried out using a trim-selected SiO ₂ -HZSM-5 catalyst as mentioned above at a temperature of 200 ° C., a pressure of 4200 kPa (600 psig) and a WHSV of 0.25. Diesel and lubricating oil products with high selectivity for the desired straight chain hydrocarbons are obtained.

Example 38

Distillate dewaxing is carried out using a trim-selected SiO ₂ -HZSM-5 catalyst as mentioned above at a temperature of 343 ° C. (650 ° F.), a pressure of 2900 kPa (400 psig) and a WHSV of 1. Selective decomposition of waxy straight chain hydrocarbons greatly improves product quality. The pour point of heavy gas oil is improved from 35 ° C. (95 ° F.) to −7 ° C. (20 ° F.).

Claims (4)

Toluene is a catalyst containing a temperature of 100 ° C. to 600 ° C., a pressure of 100 to 14000 kPa (atmospheric pressure to 2000 psig), a WHSV of 0.1 to 100 and a molecular sieve having a limiting index of 1 to 30 at a hydrogen to hydrocarbon molar ratio of 0 to 10. A process for preparing a form-selective conversion catalyst in which toluene is converted to xylene by contact, wherein the toluene is supplied in the form of a vapor phase mixture containing at least 80 wt% toluene and at least 0.1 wt% selector, A method for producing a form-selective conversion catalyst, characterized in that the organosilicon compound selected from polysiloxane, siloxane, silane, disilane and alkoxysilane having at least one silicon-hydrogen bond. The method of claim 1 wherein the molecular sieve is treated with a silicon-containing selector prior to treatment with the mixture. The method of claim 1 wherein the molecular sieve catalyst has a limiting index of 1-20. The method of claim 1 wherein the catalyst molecular sieve comprises ZSM-5.