CN1114495C - Process for preparing composite catalyst and its application - Google Patents

Abstract

A composite catalyst that can be used for olefin epoxidation, cyclohexanone ammoxidation, arene hydroxylation, saturated hydrocarbon oxidation, and alcohol oxidation is composed of 2.0-95.0% (weight) MFI structure titanium-silicon molecular sieve and 5.0-98.0% ( Heavy) composition of inorganic oxides. Titanium-silicon molecular sieves are prepared by formulating silicon source, titanium source, template agent, alkali and distilled water in a certain molar ratio, mixing them, and hydrothermal crystallization. Inorganic oxides can be pure oxides or complexes or mixtures of several types. Composite catalyst with spherical or irregular particles made by extrusion or spray molding method, suitable for batch kettle, fixed bed, moving bed reaction device.

Description

Preparation and application of a kind of composite catalyst

The invention relates to a method for preparing a catalyst for selective oxidation of organic matter and its application.

U.S. Patent No. 4,410,501 once disclosed the titanium silicon molecular sieve of MFI structure and preparation method thereof, and it is to use tetrapropyl ammonium hydroxide (abbreviated TPAOH) as template and alkali source, with tetraalkyl silicate or silica sol as The silicon source uses hydrolyzable titanium compounds as the titanium source, and they are mixed in a certain molar ratio, and the mixture is hydrothermally crystallized at 130-200° C. for 6-30 days in an autoclave.

Titanium silicate molecular sieve with MFI structure has excellent catalytic performance in a series of catalytic oxidation systems using hydrogen peroxide as oxidant. It can be applied to olefin epoxidation, cyclohexanone ammoxidation, aromatic hydrocarbon hydroxylation, saturated hydrocarbon oxidation, alcohol In reactions such as oxidation, it has the characteristics of high reaction selectivity, mild reaction conditions, simple and safe process, and environmental friendliness.

Another U.S. patent USP4,833,260 introduces an olefin epoxidation process using hydrogen peroxide as an oxidant and a titanium-silicon molecular sieve as a catalyst. The reaction temperature is 0-150°C and the pressure is 1-100 atm. Alcohol, acetone, dilute hydrogen peroxide as oxidant, ethylene, propylene, 2-butene, chloropropene, 1-octene and other olefin epoxidation, have obtained good results. However, the titanium-silicon molecular sieves used therein are in powder form or simply pressed into tablets, and cannot be used in industrial continuous devices.

Propylene oxide is synthesized by epoxidation of propylene with titanium-silicon molecular sieve as catalyst and hydrogen peroxide as oxidant, which has the advantages of high selectivity, mild conditions and no pollution, and meets the requirements of green chemistry and clean production. This process overcomes the shortcomings of the traditional chlorohydrin method that consumes a large amount of chlorine gas, causes serious environmental pollution, and has a long process, large investment, and many co-products of the indirect oxidation method. However, the propylene epoxidation process using hydrogen peroxide as an oxidant has not yet been industrialized. The main obstacles to the industrialization of this process are: (1), the high cost of the titanium-silicon molecular sieve as a catalyst; (2), the problem of forming the titanium-silicon molecular sieve has not been solved.

USP4410501 uses a large amount of high-purity TPAOH without alkali metal ions as a template to synthesize titanium-silicon molecular sieves, and the cost of the prepared titanium-silicon molecular sieves is relatively high. In recent years, there have been reports of using other templates instead of TPAOH to synthesize TS-1. Stud Surf Sci Catal, 84 (1994) 203 reported that tetrapropylammonium bromide (TPABr) was used as a template, and concentrated ammonia water was used as an alkali source to synthesize TS-1 molecular sieve. However, this method is slow in crystallization and requires high temperature, requiring 168 hours of crystallization at 185°C. Zeolites, 16 (1996) 108 reported the synthesis of TS-1 molecular sieve in TPABr-hexamethylenediamine system, and the obtained TS-1 molecular sieve showed certain activity in the hydroxylation reaction of phenol.

The titanium-silicon molecular sieve obtained by hydrothermal synthesis is an extremely fine powdery solid, which is difficult to separate from the product when directly used as a catalyst, and cannot be used for industrial continuous production. From the perspective of industrial application, EP0200260 studies the formation of titanium-silicon molecular sieve catalysts. SiO ₂ was oligomerized on the periphery of TS-1 crystals, and then sprayed to form high-strength microspheres with an average particle size of about 20 μm. The reaction was carried out in a batch reactor, the conversion rate of H ₂ O ₂ reached 97%, and the selectivity of PO reached 92%. The continuous reaction in the fixed bed reactor stabilized after 40 hours. After 400 hours of operation, the conversion rate _{of H2O2} was stable at 60%, and the selectivity of PO was 93%. TPAOH is used in large quantities in the preparation process of this catalyst, the cost is high, and its activity cannot meet the industrial requirements.

USP5736479 discloses a composite catalyst composed of a metal oxide and a titanium-silicon molecular sieve formed by in-situ crystallization on the metallization. Metal oxide refers to TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ or mixtures thereof. The titanium silicon molecular sieve in the catalyst accounts for 1-90% (weight) of the composite catalyst. The preparation method of the catalyst is: in the presence of the template agent TPAOH, the mixture of the titanium source and the silicon source is deposited on the metal oxide, or the metal oxide of the deposited silicon dioxide is fully impregnated with a titanium compound, and then placed in an autoclave React for 48-240 hours at 150-200°C and autogenous pressure. However, titanium-silicon molecular sieves are directly connected to each other on metal oxides, and the bonding strength is poor.

So far, no cheap template agent tetrapropylammonium bromide (TPABr) has been used to synthesize titanium-silicon molecular sieves with MFI structure, which is molded with inorganic oxides to make composite catalysts for the epoxidation of propylene to propylene oxide (PO) reports.

The purpose of the present invention is to provide a kind of composite catalyst that is made up of MFI structure titanium silicon molecular sieve and inorganic oxide on the basis of prior art, is used for the selective oxidation reaction such as propylene epoxidation, and provides the preparation method of this composite catalyst and its use.

The composite catalyst provided by the invention is composed of 2.0-95.0% (weight) of titanium-silicon molecular sieve with MFI structure and 5.0-98.0% (weight) of inorganic oxide. The MFI structure titanium-silicon molecular sieves are connected by inorganic oxides. Wherein, the inorganic oxide is selected from SiO ₂ , Al ₂ O ₃ or their composites.

The preparation method of the composite catalyst by spraying is to spray the mixture of titanium-silicon molecular sieve and binder directly on the inorganic oxide, and then dry and bake it; extrusion molding is to mix titanium-silicon molecular sieve with binder The extruder is extruded into strips, dried and cut into granules. The composite catalyst prepared by the above method is formed by the interaction between titanium-silicon molecular sieves with MFI structure and inorganic oxides to form a firm connection.

The method for preparing MFI structure titanium silicon molecular sieve is to combine silicon source, titanium source, template agent (such as: tetraalkylammonium bromide TRABr), alkali and distilled water in a molar ratio of 1: 0.001～0.2: 0.03～0.3: 0.1～4.0 : 20-100 to prepare a reaction glue solution, mix well, and crystallize by hydrothermal treatment at 120-200°C for 1-10 days.

The silicon source is selected from silica gel, silica sol, white carbon black or organosilicate with general formula (R ¹ O) ₄ Si, wherein R ¹ is an alkyl group with 1 to 4 carbon atoms.

Said titanium source is organic titanate or inorganic titanium salt. The general formula of organic titanate is (R ² O) ₄ Ti, wherein R ² is an alkyl group with 1 to 4 carbon atoms; the inorganic titanium salt is selected from TiCl ₄ , TiCl ₃ , TiOCl ₂ , TiOSO ₄ .

Said templating agent TRABr is selected from tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide. Due to the low price of the template agent tetrapropylammonium bromide (TPABr), the amount used in the reaction glue is low, that is, the TPABr/silicon source (molar ratio) can be reduced to 0.03-0.05, thus greatly reducing the MFI structure. The cost of titanium-silicon molecular sieve TS-1, thereby also reducing the cost of the composite catalyst.

Said alkali is ammonia water or organic amine. The general formula of the organic amine is an aliphatic amine compound of R ³ _m [NH _(3-m) ] _n , wherein R ³ is an alkyl group with 1-6 carbon atoms, m=1-3, n=1 or 2. The fatty amine compound may be selected from one of ethylamine, n-propylamine, n-butylamine, ethylenediamine, hexamethylenediamine, diethylamine, triethylamine, tripropylamine or tributylamine. When ammonia water, diethylamine, hexamethylenediamine, and ethylenediamine were selected as the base, in the infrared spectrum of the synthesized titanium-silicon molecular sieve TS-1 with MFI structure, there appeared characteristic peaks around 960cm ^-1 , which indicated that titanium entered the framework. The TS-1 molecular sieve synthesized by using TPABr as the template, ammonia, diethylamine, hexamethylenediamine, and n-butylamine as the base showed good catalytic performance in the epoxidation of propylene, and compared with TPAOH as the template. The catalytic performance of the TS-1 molecular sieve synthesized by the same reagent is comparable.

The composite catalyst provided by the invention is prepared by extrusion molding or spray molding. The extrusion molding method is to extrude the mixture of MFI structure titanium silicon molecular sieve and inorganic oxide into strips through an extruder, dry, and then cut into granules; the said spray molding method is to make the MFI structure The mixture of titanium-silicon molecular sieve, silica sol or aluminum glue and binder is sprayed on the spherical carrier.

The binder is selected from glycerin, polyvinylpyrrolidone, methylcellulose, carboxymethylcellulose, polyvinyl alcohol or a mixture of two or more of them.

The spherical support is selected from silicon pellets, Al ₂ O ₃ pellets, TiO ₂ pellets, ceramic pellets, aluminum silicate pellets, clay pellets or a mixture of two or more of them. The diameter of the spherical support is 0.2-20.0mm. In the composite catalyst prepared by the spray molding method, the titanium-silicon molecular sieve with MFI structure is evenly distributed on the surface of the spherical support, forming a thin layer with a thickness of only 0.1-0.2mm.

The composite catalyst provided by the invention can be used in reactions such as olefin epoxidation, styrene oxidation, cyclohexanone ammoxidation, aromatic hydrocarbon oxidation, saturated hydrocarbon oxidation, alcohol oxidation, etc. In the epoxidation reaction of propylene as an oxidant, the reaction temperature is 0-100° C., the pressure is 1-50 atm, methanol is used as a solvent, and propylene:H ₂ O ₂ =1-10:1 (molar ratio).

较高。由于喷涂成型法制得的复合催化剂MFI结构钛硅分子筛分布为一个薄层，反应物和产物的扩散路径较短，有利于反应物双氧水迅速到达催化活性中心上与丙烯反应，也有利于主产物环氧丙烷迅速离开催化活性中心扩散到体相，从而减少了双氧水自身分解和环氧丙烷与溶剂的副反应，提高了环氧丙烷选择性和双氧水利用率。Composite catalysts were prepared by extruding or spraying, respectively, and propylene oxide was catalyzed in a fixed-bed reactor to produce propylene oxide. The composite catalysts prepared by the two molding methods have the same catalytic activity for propylene epoxidation, but the composite catalysts prepared by the spray molding method have higher selectivity for Spo and hydrogen peroxide utilization.

higher. Since the composite catalyst MFI structure titanium-silicon molecular sieve prepared by the spray molding method is distributed as a thin layer, the diffusion path of the reactant and the product is relatively short, which is beneficial for the reactant hydrogen peroxide to quickly reach the catalytic active center to react with propylene, and is also conducive to the main product cycle. Propylene oxide quickly leaves the catalytic active center and diffuses into the bulk phase, thereby reducing the self-decomposition of hydrogen peroxide and the side reaction between propylene oxide and solvent, and improving the selectivity of propylene oxide and the utilization rate of hydrogen peroxide.

The appearance of the composite catalyst provided by the invention is strip shape, spherical shape or irregular particles. The composite catalyst can be used in batch tank, fixed bed, moving bed or catalytic rectification propylene epoxidation reaction device.

The composite catalyst prepared by the spray molding method catalyzes the propylene epoxidation reaction in a fixed-bed reactor, and the reaction results of 200 hours of long operation are shown in Table 1: Table 1 Spherical composite catalyst catalyzes the propylene epoxidation 200h reaction time (hour) (%) (%) Spo(%) SMME(%)

3 94.26 82.81 81.87 15.85

6 97.13 89.80 81.49 16.33

9 97.99 89.83 76.77 21.61

27 97.42 93.68 80.96 17.84

30 97.70 95.63 82.85 16.46

33 97.70 97.07 81.35 18.65

48 97.42 95.63 84.37 15.63

54 97.80 94.97 76.96 22.11

72 97.13 95.44 74.47 23.87

81 97.13 95.74 77.14 22.86

96 96.56 95.89 83.94 15.91

104 97.13 96.51 85.07 14.93

132 97.56 95.17 87.01 12.99

144 96.56 96.94 88.24 11.76

147 96.27 97.83 90.27 9.73

153 95.41 97.71 88.69 11.31

171 95.84 97.16 91.25 8.75

192 94.98 96.81 90.40 9.60

200 95.55 95.88 90.69 9.31

Average 96.71 94.76 83.88 15.55

为双氧水转化率； 为双氧水利用率；Spo为环氧丙烷选择性：S_MME为丙二醇单甲醚副产物选择性。in FIG. 1

is the conversion rate of hydrogen peroxide; is hydrogen peroxide utilization; Spo is propylene oxide selectivity; S _MME is propylene glycol monomethyl ether by-product selectivity.

The reaction conditions of the data in Table 1: temperature: 50°C, pressure 3.0Mpa, molar ratio of C ₃ H ₆ /H ₂ O ₂ is 4.17, solvent: methanol, H ₂ O ₂ 0.85 mol/L, weight of C ₃ H ₆ empty The speed is 0.10 h ^-1 .

和H₂O₂的利用率

保持在较高的水平，环氧丙烷选择性的平均值也达到了83.8％(副产物为环氧丙烷进一步与溶剂反应形成的丙二醇单甲醚(MME)和丙二醇(PG)，未检测到其它产物)。It can be seen from Table 1 that within 200 hours, the conversion rate of H ₂ O ₂

and H ₂ O ₂ utilization

Maintained at a relatively high level, the average value of propylene oxide selectivity has also reached 83.8% (by-products are propylene glycol monomethyl ether (MME) and propylene glycol (PG) that propylene oxide reacts with solvent to form further, do not detect other product).

The composite catalyst prepared by the spray molding method catalyzes the propylene epoxidation reaction in a single-tube enlarged fixed-bed reaction device, and the 1000-hour long-running reaction results are shown in Table 2:

Table 2 The reaction results of 1000h long-running reaction of propylene epoxidation catalyzed by spherical composite catalyst

Reaction conditions: catalyst loading 2.5Kg, propylene liquid feed 0.4Kg/h, methanol and H ₂ O ₂ mixed feed 2.5Kg/h, reactor outlet pressure 3.0Mpa, reaction temperature 55-60°C.

The average H ₂ O ₂ conversion rate is 98.05%, the propylene oxide selectivity is 92.04%, and the H ₂ O ₂ utilization rate is 98.31%. Such results have not been obtained in the prior art. It shows that the composite catalyst provided by the invention has high activity and epoxidation selectivity in the propylene epoxidation reaction using hydrogen peroxide as the oxidant, and has good industrial prospects.

The effect of the present invention: the composite catalyst prepared by extrusion molding or spray molding method is easy to separate the catalyst from the reaction product, which solves the problem of molding of MFI structure titanium-silicon molecular sieve and separation and recovery of catalyst; During use, the MFI structure titanium-silicon molecular sieve will not fall off from the composite catalyst; the composite catalyst provided by the invention can not only be used in small-scale propylene epoxidation reaction devices in the laboratory, but also can be used in large-scale industrial devices, which is a very Promising catalysts for propylene epoxidation.

Example 1

Take 2.62ml of tetrabutyl titanate, slowly drop it into 60ml of deionized water at 0-5°C, and stir for 30 minutes after the dropping. Add 11.1ml of 30% (weight) hydrogen peroxide and stir for 30min. Then add 27.2ml of 25% (weight) concentrated ammonia water and stir for 30min to obtain A solution. In another container, 60.3g 25.5% (weight) of silica sol (Qingdao Ocean Chemical Factory product), 6.82g TPABr and 0.8g MFI structure titanium silicon molecular sieve (as crystal seed) were mixed, stirred for 1 hour to obtain B solution. Add solution A into solution B, stir for 30 minutes, then raise the temperature to 70-80°C, stir and heat for 3 hours. The above reaction mixture was put into an autoclave, heated and crystallized at 170°C for 3 to 6 days, filtered, washed and dried by conventional methods, and calcined at 540°C for 5 hours to obtain 13.1g of MFI structure titanium silicon molecular sieve A.

Example 2

Take 1.31ml of tetrabutyl titanate, slowly drop it into 35ml of deionized water at 0-5°C, and stir for 30min after the dropping. Add 5.6ml of 30% (weight) hydrogen peroxide and stir for 30min. Add 2.0ml of diethylamine and stir for 30min to obtain A solution. In another container, 30.2g 25.5% (weight) silica sol (product of Qingdao Ocean Chemical Factory), 3.41g TPABr and 0.4g MFI structure titanium-silicon molecular sieve (as crystal seed) were mixed, stirred for 1 hour to obtain B solution . Add solution A into solution B, stir for 30 minutes, then raise the temperature to 70-80°C, stir and heat for 3 hours. The above reaction mixture was put into an autoclave, heated and crystallized at 170°C for 3 to 6 days, filtered, washed and dried by conventional methods, and calcined at 540°C for 5 hours to obtain 7.7g of titanium-silicon molecular sieve B with MFI structure.

Example 3

Take 1.31ml of tetrabutyl titanate, slowly drop it into 40ml of deionized water at 0-5°C, and stir for 30min after the dropping. Add 2.8ml of 30% (weight) hydrogen peroxide and stir for 30min. Add 0.9 g of hexamethylenediamine and stir for 30 min to obtain A solution. In another container, 30.2g 25.5% (weight) silica sol (Qingdao Ocean Chemical Factory product), 3.41g TPABr and 0.4gMFI structure titanium-silicon molecular sieve (as crystal seed) were mixed, stirred for 1 hour to obtain B solution. Add solution A into solution B, stir for 30 minutes, then raise the temperature to 70-80°C, stir and heat for 3 hours. The above reaction mixture was put into an autoclave, heated and crystallized at 170°C for 3 to 6 days, filtered, washed and dried by conventional methods, and calcined at 540°C for 5 hours to obtain 6.2g of titanium-silicon molecular sieve C with MFI structure.

Example 4

Take 1.31ml of tetrabutyl titanate, slowly drop it into 40ml of deionized water at 0-5°C, and stir for 30min after the dropping. Add 2.8ml of 30% (weight) hydrogen peroxide and stir for 30min. Add 1.3ml of ethylenediamine and stir for 30min to obtain A solution. In another container, 30.2g 25.5% (weight) silica sol (product of Qingdao Ocean Chemical Factory), 3.41g TPABr and 0.4g MFI structure titanium-silicon molecular sieve (as crystal seed) were mixed, stirred for 1 hour to obtain B solution . Add solution A into solution B, stir for 30 minutes, then raise the temperature to 70-80°C, stir and heat for 3 hours. The above reaction mixture was put into an autoclave, heated and crystallized at 170°C for 3 to 6 days, filtered, washed and dried by conventional methods, and calcined at 540°C for 5 hours to obtain 6.8 g of titanium-silicon molecular sieve D with MFI structure.

Example 5

Take 1.31ml of tetrabutyl titanate, slowly drop it into 40ml of deionized water at 0-5°C, and stir for 30min after the dropping. Add 2.8ml of 30% (weight) hydrogen peroxide and stir for 30min. Add 2.1ml of n-butylamine and stir for 30min to obtain A solution. In another container, 30.2g 25.5% (weight) silica sol (product of Qingdao Ocean Chemical Factory), 3.41g TPABr and 0.4g MFI structure titanium-silicon molecular sieve (as crystal seed) were mixed, stirred for 1 hour to obtain B solution . Add solution A into solution B, stir for 30 minutes, then raise the temperature to 70-80°C, stir and heat for 3 hours. The above reaction mixture was put into an autoclave, heated and crystallized at 170°C for 3-6 days, filtered, washed and dried by conventional methods, and calcined at 540°C for 5 hours to obtain 7.1g of MFI structure titanium silicon molecular sieve E.

Comparative example 1

In this comparative example, a titanium-silicon molecular sieve with an MFI structure was prepared according to the method disclosed in Example 1 of USP4410501.

Take 40ml of tetrapropylammonium hydroxide and dissolve it in 80ml of distilled water, slowly drop it into 46ml of tetraethylsilicate at 0-5°C, and stir for 20min after the dropping. 1.36ml of tetraethyl titanate was added dropwise, and stirred for 1 hour after the drop was completed. Slowly raise the temperature to 80°C, stir and heat for 5 hours, and add 100ml of deionized water. The above reaction mixture was transferred into a polytetrafluoroethylene-lined autoclave, heated and crystallized at 175°C for 10 days. After the crystallization was completed, the reactant was taken out, filtered, washed, dried, and calcined at 540°C for 6 hours to obtain the product, coded as F.

Example 6-10

Examples 6-10 illustrate the catalytic performance of the titanium-silicon molecular sieve with MFI structure provided by the present invention in the epoxidation reaction of propylene. The propylene epoxidation reaction was carried out in the following batch tanks. Examples 6-10 respectively used MFI structure titanium-silicon molecular sieve samples A, B, C, D, and E as catalysts.

In a 0.4 liter stainless steel reaction kettle, add 0.4g of MFI structure titanium silicon molecular sieve, 31.6ml of methanol and 2.0ml of 30% (weight) hydrogen peroxide. Propylene is introduced to maintain a pressure of 0.4Mpa. Magnetic stirring, constant temperature water bath heating. Samples were taken after 60 minutes of reaction, and the concentration of H ₂ O ₂ was analyzed by iodometric method. The reaction product was analyzed with a 1102 type gas chromatograph from Shanghai Analytical Instrument Factory. The fixed liquid of the chromatographic column was polyethylene glycol, and the carrier was 101 white carrier. The obtained results are listed in Table 3:

Table 3 Catalytic propylene epoxidation performance of MFI structure titanium silicate molecular sieves synthesized by different methods

Sample Templating agent Alkali (%) Spo(%) (%)

A TPABr Ammonia 92.9 85.1 98.2

B TPABr Diethylamine 96.2 88.0 93.1

C TPABr Hexamethylenediamine 95.8 82.8 91.2

D TPABr ethylenediamine 94.2 59.5 89.0

E TPABr butylamine 96.7 91.1 93.2

F TPAOH Tetrapropylammonium Hydroxide 94.2 94.6 96.5

Reaction conditions: reaction temperature 60°C, H ₂ O ₂ 0.45 mol/L, propylene pressure 0.4Mpa, catalyst: 11.9g/L, reaction time: 1 hour, solvent: methanol.

Comparative example 2

This comparative example illustrates the catalytic performance of the titanium-silicon molecular sieve with MFI structure prepared according to the method disclosed in Example 1 of USP4410501 in the epoxidation of propylene.

The propylene epoxidation reaction was carried out in a batch tank, and the reaction conditions were the same as in Examples 6-10, but the MFI structure titanium-silicon molecular sieve sample F prepared in Comparative Example 1 was used as a catalyst. The reaction results are shown in Table 3.

Example 11

This example illustrates the catalytic performance of the titanium silicate molecular sieve with MFI structure provided by the present invention in the epoxidation reaction of allyl chloride. The epoxidation reaction of allyl chloride was carried out in a batch tank, and the MFI structure titanium-silicon molecular sieve sample A was used as a catalyst.

In a 0.4 liter stainless steel reaction kettle, add 0.5g of MFI structure titanium silicon molecular sieve, 20ml of methanol, 1.75ml of 9.99MH ₂ O ₂ , 5g of chloropropene, stir magnetically, heat in a constant temperature water bath, and react at 40°C for 1h. The reaction result is: the conversion rate of H ₂ O ₂ is 72.5%, the epichlorohydrin in the product accounts for 96.7%, the monomethyl ether of 3-chloropropanediol accounts for 3.3%, and the utilization rate of H ₂ O ₂ is 95.3%.

Example 12

This example illustrates the catalytic performance of the MFI structure titanium silicate molecular sieve provided by the present invention in the oxidation reaction of styrene. The styrene oxidation reaction was carried out in a batch tank, and the MFI structure titanium-silicon molecular sieve sample A was used as a catalyst.

In a 0.4 liter stainless steel reaction kettle, add 1.0 g of MFI structure titanium silicon molecular sieve, 30 ml of methanol, 10 ml of styrene, and 5 ml of 9.57M H ₂ O ₂ . Magnetic stirring, heating in a constant temperature water bath, and reacting at 75°C for 6h. The result of the reaction is: the conversion rate of styrene is 20.99%, the benzaldehyde in the product accounts for 54.45%, the phenylacetaldehyde accounts for 8.88%, and the acetophenone accounts for 36.67%.

Example 13

This example illustrates the catalytic performance of the titanium-silicon molecular sieve with MFI structure provided by the present invention in the hydroxylation reaction of phenol. The hydroxylation reaction of phenol was carried out in a batch kettle, and the titanium-silicon molecular sieve sample A with MFI structure was used as a catalyst.

The reaction conditions are: phenol/H ₂ O ₂ =3:1 (mol/mol), add 0.05g of MFI structure titanium silicon molecular sieve as catalyst and 0.17ml of acetone as solvent for every g of phenol. Magnetic stirring, heating in a constant temperature water bath, and reacting at 80°C for 6h. The reaction result is: the conversion rate of phenol is 12.8%, catechol accounts for 47.3%, hydroquinone accounts for 42.6%, and p-benzoquinone accounts for 10.1% in the product.

Example 14

Mix 3.0g of the MFI structure titanium-silicon molecular sieve sample E prepared by Example 5 of the present invention, 1.5g of turnip powder, 20ml of 30% (weight) silica sol, 21.0g of white carbon black, and 5ml of deionized water, and knead repeatedly Knead, extrude into thin strips with a diameter of 1 mm with an extruder, then cut into particles with a length of 2 to 3 mm, dry naturally at room temperature, and roast at 540 ° C for 5 hours to obtain a strip-shaped composite catalyst.

Example 15

The MFI structure titanium-silicon molecular sieve sample E prepared according to Example 5 of the present invention, 30% by weight of silica sol and deionized water were mixed in a weight ratio of 1:5:5 and stirred to obtain a uniform suspension. Spray the suspension with compressed air on the surface of aluminum silicate pellets with a diameter of 2-3 mm, and heat and dry to form a thin layer of titanium-silicon molecular sieve with MFI structure on the surface of the aluminum silicate pellets. Finally, it was calcined at 540° C. for 5 hours to obtain a spherical composite catalyst.

The crushing strength of the spherical composite catalyst was 25.8Kgf.

Example 16

Put 8.0 g of the strip-shaped composite catalyst prepared according to Example 14 of the present invention into a pressurized fixed-bed reactor made of stainless steel, and keep the system pressure at 3.0 Mpa. Turn on the heating electric furnace to the reaction temperature (60° C.), open the feed valves of the methanol solution of H ₂ O ₂ and propylene, and carry out the reaction for 24 hours. The concentration of H ₂ O ₂ in methanol solution is 0.85mol/l. C ₃ H ₆ /H ₂ O ₂ (molar ratio) = 4.17. The total space velocity is 0.56h ^-1 . Samples were regularly taken from the receiving pipe in the cold bath for analysis. The average results of the 24-hour reaction were: H ₂ O ₂ conversion rate 97.66%, H ₂ O ₂ utilization rate 78.63%, and PO selectivity 76.4%.

Example 17

The spherical composite catalyst was used instead of the strip composite catalyst to carry out the propylene epoxidation reaction, and the reaction conditions were the same as in Example 16. The average result of reaction for 24 hours is: H ₂ O ₂ conversion rate 97.63%, H ₂ O ₂ utilization rate 90.54%, PO selectivity 81.96%.

Example 18

6.0 g of the spherical composite catalyst prepared according to Example 15 of the present invention was loaded into a pressurized fixed-bed reactor made of stainless steel, and a long run of 200 h of propylene epoxidation reaction was carried out. The reaction conditions are: reaction temperature 50°C, pressure 3.0Mpa, methanol as solvent, concentration of H ₂ O ₂ in methanol solution is 0.85mol/l, C ₃ H ₆ /H ₂ O ₂ (molar ratio) = 4.17, propylene empty The speed is 0.10h ^-1 . The reaction results are listed in Table 1.

Example 19

2.5 Kg of the spherical composite catalyst prepared according to Example 15 of the present invention was loaded into a stainless steel single-tube enlarged fixed-bed reactor, and a long run of 1000 h of propylene epoxidation reaction was carried out. The reaction results are shown in Table 2.

Claims (9)

1, a kind of composite catalyst of being made up of MFI structure titanium silicon molecular sieve and metal oxide is characterized in that this composite catalyst is the inorganic oxide SiO by the MFI structure titanium silicon molecular sieve and 5.0～98.0% (weight) of 2.0～95.0% (weights) ₂Or Al ₂O ₃And the compound composition, their mixture adopts extrusion or spray mo(u)lding to make between the MFI structure titanium silicon molecular sieve by firmly being connected with the interaction of inorganic oxide.

2, a kind of preparation method with the described composite catalyst of claim 1, it is characterized in that it at first being the preparation of MFI structure titanium silicon molecular sieve, promptly be with the silicon source, the titanium source, the template agent, alkali and distilled water, 1: 0.001 in molar ratio～0.2: 0.03～0.3: 0.1～4.0: 20～100 are made into glue, after mixing, made in 1～10 day at 120～200 ℃ of following hydrothermal crystallizings, then MFI structure titanium silicon molecular sieve and inorganic oxide are made into mixture by the described weight percent composition of claim 1, after extruded moulding method or spray mo(u)lding method are made graininess or spherical composite catalyst.

3, according to the preparation method of the described composite catalyst of claim 3, the silicon source that it is characterized in that preparing the MFI structure titanium silicon molecular sieve is that to be selected from silica gel, Ludox, white carbon black or general formula be (R ¹O) ₄The organosilicon acid esters of Si, wherein R ¹It is the alkyl of 1～4 carbon atom.

4, according to the preparation method of claims 3 described composite catalysts, the titanium source that it is characterized in that preparing the MFI structure titanium silicon molecular sieve is to be selected from inorganic titanium salt TiCl ₄, TiCl ₃, TiOCl ₂, TiOSO ₄Or general formula is (R ²O) ₄The organic titanate of Ti, wherein R ²It is the alkyl of 1～4 carbon atom.

5, according to the preparation method of the described composite catalyst of claim 3, the template agent that it is characterized in that preparing the MFI structure titanium silicon molecular sieve is tetraalkyl ammonium bromide (TRABr), i.e. tetraethylammonium bromide, 4-propyl bromide or TBAB.

6, according to the preparation method of the described composite catalyst of claim 3, it is characterized in that preparing the used alkali of MFI structure titanium silicon molecular sieve is ammoniacal liquor or organic amine, and the general formula of organic amine is R ³M[NH (3-m)] fat amine compound of n, wherein R ³Be the alkyl of 1～6 carbon atom, m=1～3, n=1 or 2 one of can be selected from ethamine, n-propylamine, n-butylamine, ethylenediamine, hexamethylene diamine, diethylamine, triethylamine, tripropyl amine (TPA) or the tri-n-butylamine.

7, according to the preparation method of the described composite catalyst of claim 3, it is characterized in that described extruded moulding method is the mixture with MFI structure titanium silicon molecular sieve and inorganic oxide, be extruded into strip, oven dry, be cut into graininess again by banded extruder; And the spray mo(u)lding method to be mixture with MFI structure titanium silicon molecular sieve and Ludox or aluminium glue and binding agent be sprayed on the spherical carrier surface that diameter is 0.2～20.0mm, it is the thin layer of 0.1～0.2mm that drying, roasting form thickness; Binding agent is selected from glycerine, polyvinylpyrrolidone, methylcellulose, carboxymethyl cellulose, polyvinyl alcohol or the mixture in them; Spherical carrier is selected from silicon bead, Al ₂O ₃Bead, TiO ₂Bead, ceramic bead, alumina silicate bead, clay bead or their mixture.

8, a kind of purposes with the described composite catalyst of claim 1, it is characterized in that composite catalyst can be used for alkene epoxidation, styrene oxidation, ammoxidation of cyclohexanone, aromatic hydrocarbons hydroxylating, saturated hydrocarbons oxidation and oxidation of alcohols, be applicable to during reaction in batch still, fixed bed or the moving bed device, make corresponding product.

9, a kind of purposes with the described composite catalyst of claim 1, when it is characterized in that adopting spherical composite catalyst, the propylene to prepare epoxy propane that with the hydrogen peroxide is oxidant is in fixed bed reactors, and methyl alcohol is solvent, propylene: H ₂O ₂=1 ~ 10: 1 (mol ratio), reaction temperature are 0 ~ 100 ℃, pressure 1 ~ 50atm, and in 200 ~ 1000 hours reaction time, the selectivity of expoxy propane is 84 ~ 98%, H ₂O ₂Conversion ratio be 96 ~ 99%, H ₂O ₂Utilization rate 95 ~ 99%.