A method for preparing a catalyst for synthesizing propylene oxide

Abstract

The application discloses a preparation method of a synthetic propylene oxide catalyst. Specifically, methyl allyl diphosphate triammonium salt and vinyl ferrocene are subjected to addition reaction with mercapto respectively, the amino group of guanidino 5'-ammonium phosphonate is subjected to addition reaction with methyl allyl, and TS-1 zeolite is subjected to impregnation modification; the transition metal complex has good catalytic performance and can promote the generation of propylene oxide in the reaction of catalytic synthesis of propylene oxide; the conversion rate of propylene liquid phase epoxidation reaction and the selectivity of propylene oxide can be obviously improved; the process is simple, the reaction condition is mild, and the byproduct is few, so the application belongs to a green and environment-friendly technology.

Description

Technical Field

[0001] The present invention relates to the technical field of propylene oxide catalysts, in particular to a method for preparing a catalyst for synthesizing propylene oxide. Background Art

[0002] Propylene oxide is one of the three major derivatives of propylene. Due to the problems of environmental pollution, process complexity and by-products in the traditional chlorohydrin and co-oxidation production processes, people have placed high hopes on the new technology of liquid-phase epoxidation of propylene and hydrogen peroxide to synthesize propylene oxide using titanium silicalite TS-1 as a catalyst in the past 30 years. The advantage of this process is that it can overcome the above-mentioned shortcomings of the traditional process, and can use low-concentration hydrogen peroxide as the oxidant. Its reaction conditions are mild and it belongs to green chemical technology.

[0003] Chinese patent CN202110463168.6: relates to a catalyst for preparing propylene oxide by gas-phase epoxidation of propylene and its preparation method. The catalyst of the present invention is a supported single-atom Au catalyst, comprising an active component single-atom Au and a carrier molecular sieve. By mass ratio, the molecular sieve is 97.0% to 99.99%, and Au is 0.01% to 3.0%. The single-atom Au is confined in the microporous channels of the carrier molecular sieve. The catalyst is used for the reaction of propylene gas-phase epoxidation to propylene oxide with O2 as the oxidant and H2 in the presence of H2. Under mild reaction conditions (reaction temperature of 80 to 350°C, reaction pressure of 0.1 to 0.6 MPa), the propylene oxide selectivity is ≥98%, the propylene conversion rate is ≥14%, and it has good stability. The single-atom Au catalyst is synthesized by impregnation method, does not use organic solvents and surfactants, is environmentally friendly, the components are easy to control, the process is simple and convenient, the cost is low, the repeatability is good, and it is suitable for industrial production.

[0004] Chinese patent CN202111058005.6 discloses a catalyst for the HPPO synthesis of propylene oxide, its preparation method, and its application. The preparation method includes the steps of preparing an MWW molecular sieve precursor, preparing an MWW molecular sieve, and preparing a titanium silicalite molecular sieve Ti-MWW, which is a catalyst for the HPPO synthesis of propylene oxide. The catalyst prepared by the present method is used in the HPPO synthesis of propylene oxide, improving propylene conversion and propylene oxide selectivity.

[0005] Chinese patent CN201711024586.5 discloses a method for preparing a propylene epoxidation catalyst. A silicon source is pre-hydrolyzed, and then a titanium source is added to form a sol. The sol is atomized and sprayed into liquid ammonia to form a sol. The sol is then expanded and dried, calcined, and silanized to produce a Ti-SiO2 composite oxide catalyst. This catalyst can be used in the propylene epoxidation process to produce propylene oxide, achieving an average selectivity of 97.5% for propylene oxide, demonstrating promising industrial applications.

[0006] In summary, based on the above discussion of the prior art methods for synthesizing propylene oxide catalysts, the current novel process for synthesizing propylene oxide by liquid-phase epoxidation with hydrogen peroxide uses water as the sole byproduct. However, due to the presence of hydrolysis and solvolysis side reactions, the process actually also produces a considerable amount of byproducts such as propylene glycol and propylene glycol methyl ether, significantly reducing the selectivity of the epoxidation reaction. Therefore, how to reduce the output of these byproducts and improve the selectivity of the epoxidation reaction as much as possible has become the key to the economic efficiency and market competitiveness of this process technology. Summary of the Invention

[0007] The present invention aims to meet these needs and provide a method for preparing a catalyst for synthesizing propylene oxide, which method does not have the disadvantages of the prior art methods discussed above. The method is simple in process, has mild reaction conditions, produces few by-products, and is a green and environmentally friendly technology.

[0008] Specifically, a preparation method for a catalyst for synthesizing propylene oxide comprises the following steps:

[0009] S1: Weigh 20-40 parts of silver nitrate and dissolve it in 500-1000 parts of deionized water, add 60-70 parts of p-mercaptoterephthalic acid and 2-5 parts of zinc chloride, then add 100-150 parts of TS-1 molecular sieve to the solution, heat and stir to react, then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver;

[0010] S2: Then, the organic silver-containing TS-1 molecular sieve is placed in 500-1000 parts of DMF, and 4-12 parts of dimethylallyl triammonium diphosphate, 0.001-0.2 parts of vinyl ferrocene, and 2-5 parts of sodium ethoxide are added, and the mixture is stirred for reaction;

[0011] S3: Add 0.04-0.5 parts of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash and dry to obtain a catalyst for synthesizing propylene oxide.

[0012] Typically, the reaction temperature of S1 is 30-40° C., and the reaction time is 100-200 minutes.

[0013] Typically, the drying temperature of S1 is 100-120°C.

[0014] Typically, the stirring rate is 300-500 rpm.

[0015] Typically, the reaction temperature of S2 is 50-60°C and the reaction time is 40-100 minutes.

[0016] Typically, the stirring time of S3 is 6-10 hours.

[0017] Typically, the drying temperature of S3 is 90-110°C.

[0018] Reaction mechanism:

[0019] (1) Silver nitrate reacts with p-mercaptoterephthalic acid to form an organometallic complex, which is then loaded into TS-1 molecular sieve;

[0020] (2) Methylallyl diphosphate triammonium salt and vinyl ferrocene react with thiol groups respectively;

[0021] (3) The amino group of guanidino 5'-aminophosphoric acid ammonium salt undergoes addition reaction with methyl allyl group to obtain a catalyst for synthesizing propylene oxide.

[0022] Technical effect:

[0023] The preparation method of a catalyst for synthesizing propylene oxide of the present invention has the following significant effects compared with the prior art:

[0024] 1. The present invention uses methylallyl diphosphate triammonium salt and vinyl ferrocene to react with thiol groups, and the amino group of guanidino 5'-aminophosphoric acid ammonium salt to react with methylallyl groups to impregnate and modify TS-1 zeolite. The transition metal complex has good catalytic performance and can promote the formation of propylene oxide in the catalytic synthesis of propylene oxide. It can significantly improve the conversion rate and propylene oxide selectivity of the liquid-phase epoxidation reaction of propylene.

[0025] 2. The process of the present invention is simple, the reaction conditions are mild, and there are few by-products, which is a green and environmentally friendly technology. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to implementation examples. The following implementation examples are illustrative rather than restrictive, and the scope of protection of the present invention cannot be limited by the following implementation examples.

[0027] Example 1

[0028] A preparation method for a catalyst for synthesizing propylene oxide, comprising the following steps:

[0029] S1: Weigh 20g of silver nitrate and dissolve it in 500g of deionized water, add 60g of para-mercaptoterephthalic acid and 2g of zinc chloride, and then add 100g of TS-1 molecular sieve to the solution. Heat and stir to react, then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver;

[0030] S2: Then, the organic silver-containing TS-1 molecular sieve was placed in 500 g of DMF, and 4 g of dimethylallyl triammonium diphosphate, 0.001 g of vinyl ferrocene, and 2 g of sodium ethoxide were added, and the mixture was stirred for reaction;

[0031] S3: Add 0.04 g of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash, and dry to obtain a catalyst for synthesizing propylene oxide.

[0032] The reaction temperature of S1 is 30° C. and the reaction time is 100 minutes.

[0033] The drying temperature of S1 is 100°C.

[0034] The stirring rate is 300 rpm.

[0035] The reaction temperature of S2 is 50°C and the reaction time is 40 minutes.

[0036] The stirring time of S3 is 6h.

[0037] The drying temperature of S3 is 90°C.

[0038] Example 2

[0039] A preparation method for a catalyst for synthesizing propylene oxide, comprising the following steps:

[0040] S1: Weigh 25g of silver nitrate and dissolve it in 600g of deionized water, add 64g of para-mercaptoterephthalic acid and 3g of zinc chloride, and then add 110g of TS-1 molecular sieve to the solution. Heat and stir to react, then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver;

[0041] S2: Then, the organic silver-containing TS-1 molecular sieve was placed in 600 g of DMF, and 6 g of dimethylallyl triammonium diphosphate, 0.1 g of vinyl ferrocene, and 3 g of sodium ethoxide were added, and the mixture was stirred for reaction;

[0042] S3: Add 0.2 g of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash, and dry to obtain a catalyst for synthesizing propylene oxide.

[0043] The reaction temperature of S1 is 35° C. and the reaction time is 140 minutes.

[0044] The drying temperature of S1 is 105°C.

[0045] The stirring rate is 350 rpm.

[0046] The reaction temperature of S2 is 55°C and the reaction time is 60 minutes.

[0047] The stirring time of S3 is 7h.

[0048] The drying temperature of S3 is 95°C.

[0049] Example 3

[0050] A preparation method for a catalyst for synthesizing propylene oxide, comprising the following steps:

[0051] S1: Weigh 35g of silver nitrate and dissolve it in 900g of deionized water. Add 68g of para-mercaptoterephthalic acid and 4g of zinc chloride. Then add 140g of TS-1 molecular sieve to the solution. Heat and stir to react. Then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver.

[0052] S2: Then, the organic silver-containing TS-1 molecular sieve was placed in 900 g of DMF, and 10 g of dimethylallyl triammonium diphosphate, 0.15 g of vinyl ferrocene, and 4 g of sodium ethoxide were added, and the mixture was stirred for reaction;

[0053] S3: Add 0.4 g of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash, and dry to obtain a catalyst for synthesizing propylene oxide.

[0054] The reaction temperature of S1 is 35° C. and the reaction time is 180 minutes.

[0055] The drying temperature of S1 is 115°C.

[0056] The stirring rate is 450 rpm.

[0057] The reaction temperature of S2 is 55°C and the reaction time is 80 minutes.

[0058] The stirring time of S3 is 9h.

[0059] The drying temperature of S3 is 105°C.

[0060] Example 4

[0061] A preparation method for a catalyst for synthesizing propylene oxide, comprising the following steps:

[0062] S1: Weigh 40g of silver nitrate and dissolve it in 1000g of deionized water, add 70g of para-mercaptoterephthalic acid and 5g of zinc chloride, then add 150g of TS-1 molecular sieve to the solution, heat and stir to react, then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver;

[0063] S2: Then, the organic silver-containing TS-1 molecular sieve was placed in 1000 g of DMF, and 12 g of dimethylallyl triammonium diphosphate, 0.2 g of vinyl ferrocene, and 5 g of sodium ethoxide were added, and the mixture was stirred for reaction;

[0064] S3: Add 0.5 g of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash, and dry to obtain a catalyst for synthesizing propylene oxide.

[0065] The reaction temperature of S1 is 40° C. and the reaction time is 200 minutes.

[0066] The drying temperature of S1 is 120°C.

[0067] The stirring rate is 500 rpm.

[0068] The reaction temperature of S2 is 60°C and the reaction time is 100 minutes.

[0069] The stirring time of S3 is 10h.

[0070] The drying temperature of S3 is 110°C.

[0071] Comparative Example 1

[0072] A preparation method for a catalyst for synthesizing propylene oxide, comprising the following steps:

[0073] S1: Weigh 20g of silver nitrate and dissolve it in 500g of deionized water, add 2g of zinc chloride, and then add 100g of TS-1 molecular sieve to the solution. Heat and stir to react, then filter, wash and dry to obtain TS-1 molecular sieve containing organic silver;

[0074] S2: Then, the organic silver-containing TS-1 molecular sieve was placed in 500 g of DMF, and 4 g of dimethylallyl triammonium diphosphate, 0.001 g of vinyl ferrocene, and 2 g of sodium ethoxide were added, and the mixture was stirred for reaction;

[0075] S3: Add 0.04 g of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash, and dry to obtain a catalyst for synthesizing propylene oxide.

[0076] The reaction temperature of S1 is 30° C. and the reaction time is 100 minutes.

[0077] The drying temperature of S1 is 100°C.

[0078] The stirring rate is 300 rpm.

[0079] The reaction temperature of S2 is 50°C and the reaction time is 40 minutes.

[0080] The stirring time of S3 is 6h.

[0081] The drying temperature of S3 is 90°C.

[0082] Comparative Example 2

[0083] A preparation method of a propylene oxide synthesis catalyst, the operation steps of which are as follows:

[0084] S1: 20g of silver nitrate is weighed and dissolved in 500g of ionized water, 60g of p-mercapto terephthalic acid is added, and then 100g of TS-1 molecular sieve is added to the solution, heated and stirred for reaction, and after filtration, washing and drying, the organic silver-containing TS-1 molecular sieve is obtained;

[0085] S2: Then the organic silver-containing TS-1 molecular sieve is placed in 500g of DMF, 4g of dimethylallyl diphosphate ammonium salt, 0.001g of vinyl ferrocene, and 2g of sodium ethoxide are added, and stirred for reaction;

[0086] S3: 0.04g of guanidyl 5'-amino phosphoric acid ammonium salt is added, and stirring is continued, and after filtration, washing and drying, the propylene oxide synthesis catalyst is obtained.

[0087] The reaction temperature of S1 is 30℃, and the time is 100 minutes.

[0088] The drying temperature of S1 is 100℃.

[0089] The stirring rate is 300rpm.

[0090] The reaction temperature of S2 is 50℃, and the time is 40 minutes.

[0091] The stirring time of S3 is 6h.

[0092] The drying temperature of S3 is 90℃.

[0093] Comparative Example 3

[0094] A preparation method of a propylene oxide synthesis catalyst, the operation steps of which are as follows:

[0095] S1: 20g of silver nitrate is weighed and dissolved in 500g of ionized water, 60g of p-mercapto terephthalic acid, and 2g of zinc chloride are added, and then 100g of TS-1 molecular sieve is added to the solution, heated and stirred for reaction, and after filtration, washing and drying, the organic silver-containing TS-1 molecular sieve is obtained;

[0096] S2: Then the organic silver-containing TS-1 molecular sieve is placed in 500g of DMF, 0.001g of vinyl ferrocene, and 2g of sodium ethoxide are added, and stirred for reaction;

[0097] S3: 0.04g of guanidyl 5'-amino phosphoric acid ammonium salt is added, and stirring is continued, and after filtration, washing and drying, the propylene oxide synthesis catalyst is obtained.

[0098] The reaction temperature of S1 is 30° C. and the reaction time is 100 minutes.

[0099] The drying temperature of S1 is 100°C.

[0100] The stirring rate is 300 rpm.

[0101] The reaction temperature of S2 is 50°C and the reaction time is 40 minutes.

[0102] The stirring time of S3 is 6h.

[0103] The drying temperature of S3 is 90°C.

[0104] Catalyst Evaluation Method: 34 g of 50% (mass fraction) H₂O₂ was prepared in 250 mL of methanol solution. 0.4 g of the catalyst and 40 mL of the methanol solution were added to a reactor. The reactor was sealed and the air was repeatedly replaced with propylene gas. The reaction was stirred at 40°C and 0.6 MPa for 1 hour. The product was analyzed using a GC-7890F chromatographic analyzer (FID flame ionization detector, injector temperature 250°C). The H₂O₂ content in the product solution was determined by titration, and the conversion and selectivity were then calculated.

[0105] Table 2 Conversion rate and propylene oxide selectivity of the reaction of the embodiment and the comparative example

[0106] Conversion of the propylene liquid phase epoxidation reaction / % Propylene oxide selectivity / % Example 1 94.71 95.87 Example 2 95.27 97.06 Example 3 96.53 99.07 Example 4 96.02 98.38 Comparative Example 1 80.29 83.63 Comparative Example 2 85.37 88.12 Comparative Example 3 88.25 89.61

[0107] By comparing the data of the above examples with the comparative examples, it can be seen that the catalyst prepared by the present invention has good catalytic performance. In the reaction of catalyzing the synthesis of propylene oxide, it can promote the formation of propylene oxide and significantly improve the conversion rate and propylene oxide selectivity of the propylene liquid phase epoxidation reaction.

[0108] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for synthesizing propylene oxide, wherein the steps are as follows: S1: Weigh 20-40 parts of silver nitrate and dissolve it in 500-1000 parts of deionized water, add 60-70 parts of p-mercaptoterephthalic acid and 2-5 parts of zinc chloride to obtain a mixed solution, then add 100-150 parts of TS-1 molecular sieve to the mixed solution, heat and stir to react, and then filter, wash and dry to obtain the organic silver-containing TS-1 molecular sieve; S2: Then, the organic silver-containing TS-1 molecular sieve is placed in 500-1000 parts of DMF, and 4-12 parts of dimethylallyl triammonium diphosphate, 0.001-0.2 parts of vinyl ferrocene, and 2-5 parts of sodium ethoxide are added, and the mixture is stirred for reaction; S3: Add 0.04-0.5 parts of guanidine 5'-aminophosphoric acid ammonium salt, continue stirring, filter, wash and dry to obtain a catalyst for synthesizing propylene oxide.

2. The method for preparing a catalyst for synthesizing propylene oxide according to claim 1, wherein: The reaction temperature of S1 is 30-40° C. and the reaction time is 100-200 minutes.

3. The method for preparing a catalyst for synthesizing propylene oxide according to claim 1, wherein: The drying temperature of S1 is 100-120°C.

4. The method for preparing a catalyst for synthesizing propylene oxide according to claim 1, wherein: The reaction temperature of S2 is 50-60°C and the reaction time is 40-100 minutes.

5. The method for preparing a catalyst for synthesizing propylene oxide according to claim 1, wherein: The stirring time of S3 is 6-10h.

6. The method for preparing a catalyst for synthesizing propylene oxide according to claim 1, wherein: The drying temperature of S3 is 90-110°C.