Bimetal modified ZSM-11 zeolite catalyst, preparation method and application

Abstract

The invention discloses a bimetallic modified ZSM-11 zeolite catalyst as well as a preparation method and application thereof. According to the catalyst, two metal oxides MOx-M 'Ox are loaded on an H-ZSM-11 molecular sieve, M is Mg or Ca, M' is La or Ce, a NaZSM-11 catalyst matrix is synthesized through a hydrothermal reaction, the obtained matrix is subjected to acid exchange, modification by loading the two metal oxides, washing, drying and roasting, and finally the catalyst is obtained. The prepared catalyst is suitable for preparing p-diethylbenzene through ethylbenzene ethanol / ethylene alkylation, the conversion rate is higher than 21%, the selectivity of p-diethylbenzene is higher than 97%, and the catalyst has the advantages of being high in activity, good in target product selectivity, easy to reuse and regenerate and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of high-efficiency catalytic synthesis catalysts for p-diethylbenzene, and in particular relates to a bimetallic modified ZSM-11 zeolite catalyst, a preparation method and an application thereof. Background Art

[0002] p-Diethylbenzene is an important chemical raw material, which is mainly prepared by ethylbenzene ethanol / ethylene alkylation reaction. The alkylation catalysts used in the past are AlCl 3 、FeCl 3 , BF 3 , HF, HCl or molecular sieve catalysts, etc., have the problems of short service life and low selectivity. For this reason, people are committed to developing highly stable and highly selective alkylation catalysts, but the effect is still not ideal.

[0003] The invention patent application with application number CN90101436.2 discloses a "catalyst for the alkylation of ethylbenzene and ethanol to synthesize p-diethylbenzene". Specifically, the HZSM-5 molecular sieve is modified with aluminum, magnesium and other components and then calcined. However, the maximum ethylbenzene conversion rate is only 10%, and the p-diethylbenzene selectivity is 95~98%.

[0004] The invention patent application number is CN200310116628.X, which discloses a "preparation and application of nano HZSM-5 zeolite metal ion composite modified catalyst", which is based on nano HZSM-5 molecular sieve and Al 2 O 3 The modified catalyst is prepared by using 1-2 active components containing lanthanum, silicon, phosphorus or magnesium as the matrix. It is applied to the synthesis of p-diethylbenzene by ethylbenzene-ethylene alkylation. The p-diethylbenzene selectivity is maintained at 97.0%, but the diethylbenzene yield is only 10.35-16.50%, that is, the conversion rate is low, which increases the energy consumption of single-pass production.

[0005] The Chinese invention patent application with application number 94110202.5 discloses a "preparation and application of silicon-mixed rare earth modified catalyst", which uses silicon-mixed rare earth modified HZSM-5 molecular sieve catalyst. The ethylbenzene conversion rate is 19.2%, but the selectivity for diethylbenzene is only 95%. The relatively low selectivity limits the industrial application of the catalyst. Summary of the invention

[0006] The present invention aims to solve the above technical problems existing in the prior art and provides a bimetallic modified ZSM-11 zeolite catalyst, a preparation method and an application thereof.

[0007] The technical solution of the present invention is: a bimetallic modified ZSM-11 zeolite catalyst is a catalyst in which two metal oxides MO are loaded on H-ZSM-11 molecular sieve.x -M'O x , named MO x -M'O x / H-ZSM-11, wherein M is Mg or Ca, M' is La or Ce, x is 1-3, and MO x The mass percentage of H-ZSM-11 is 1.5-4.0%, and the M'O x The mass percentage of H-ZSM-11 is 3.0-7.5%.

[0008] A method for preparing the above-mentioned bimetallic modified ZSM-11 zeolite catalyst is carried out according to the following steps: Step 1. preparing H-ZSM-11 molecular sieve; Step 2: Metal salts were loaded onto H-ZSM-11 molecular sieves by impregnation, and the obtained solid was calcined to obtain bimetallic modified catalyst MO. x -M'O x / H-ZSM-11.

[0009] Preferably, the step 1 is to mix 30wt% silica sol, sodium metaaluminate, tetrabutylammonium bromide, Na 2 O and water are mixed, crystallized at 80-200℃ for 5-120 h, washed and dried, and then calcined at 400-650℃ for 4-48 h to obtain NaZSM-11 matrix; the NaZSM-11 matrix is ​​mixed with an ammonium nitrate solution and allowed to stand, the solid obtained after filtration is dried, and then calcined at 200-650° C. for 4-120 hours to obtain a HZSM-11 catalyst.

[0010] Preferably, the step 2 is to immerse the H-ZSM-11 molecular sieve in two metal salt solutions of M-M', and the obtained solid is dried and then calcined at 500-600° C. for 4-48 hours.

[0011] Preferably, the step 2 is to immerse the H-ZSM-11 molecular sieve in a metal salt solution of M, and then dry the obtained solid and calcine it at 500-600°C for 4-48h to obtain the product MO. x / H-ZSM-11; then the product MO x / H-ZSM-11 is impregnated in a M' metal salt solution, and the obtained solid is dried and calcined at 500-600°C for 4-48h.

[0012] An application of the bimetallic modified ZSM-11 zeolite catalyst in the alkylation of ethylbenzene to prepare p-diethylbenzene.

[0013] The present invention is to load two kinds of metal oxides MO on H-ZSM-11 molecular sieve x -M'Ox , wherein M is Mg or Ca, and M' is La or Ce. The prepared catalyst is suitable for the alkylation of ethylbenzene ethanol / ethylene to prepare p-diethylbenzene, with a conversion rate higher than 21% and a p-diethylbenzene selectivity higher than 97%. It has the advantages of high activity, good selectivity for the target product, and easy reuse and regeneration of the catalyst. DETAILED DESCRIPTION Example 1

[0014] The bimetallic modified ZSM-11 zeolite catalyst of the present invention is prepared according to the following method: Step 1. Preparation of H-ZSM-11 molecular sieve: 30 wt% silica sol, sodium aluminate, tetrabutylammonium bromide, Na 2 O mixed with water, SiO 2 and Al 2 O 3 The molar ratio is 60:1, crystallized at 175 °C for 23 h, washed and dried, and then calcined at 550 °C for 6 h to obtain NaZSM-11 matrix; the NaZSM-11 matrix is ​​mixed with ammonium nitrate solution and allowed to stand, the solid obtained after filtration is dried, and then calcined at 550 °C for 6 h, and the reaction is repeated 2-3 times to obtain HZSM-11 catalyst.

[0015] Step 2: The H-ZSM-11 molecular sieve was impregnated in a magnesium salt and lanthanum salt solution, and the obtained solid was dried and calcined at 550 °C for 26 h to obtain the catalyst MgO-La 2 O 3 / H-ZSM-11, where the mass percentage of MgO and H-ZSM-11 is 2.5%, La 2 O 3 The mass percentage of H-ZSM-11 is 6.0%. Example 2

[0016] The bimetallic modified ZSM-11 zeolite catalyst of the present invention is prepared according to the following method: Step 1. Prepare H-ZSM-11 molecular sieve, the specific method is the same as Example 1; Step 2. Place the HZSM-11 catalyst in a magnesium salt solution, dry the solid at 120 °C for 26 h, and calcine at 550 °C for 26 h to obtain catalyst MO. x / H-ZSM-11; then the catalyst MO x / H-ZSM-11 was placed in a lanthanum salt solution, and the obtained solid was dried at 120 °C for 26 h and calcined at 550 °C for 26 h to obtain the catalyst MgO-La 2 O 3 / H-ZSM-11, where the mass percentage of MgO and H-ZSM-11 is 2.5%, La 2 O 3 The mass percentage of H-ZSM-11 is 6.0%. Example 3

[0017] The bimetallic modified ZSM-11 zeolite catalyst of the present invention is prepared according to the following method: Step 1. Prepare H-ZSM-11 molecular sieve, the specific method is the same as Example 1; Step 2: The H-ZSM-11 molecular sieve was impregnated in a magnesium salt and cerium salt solution, and the obtained solid was dried and calcined at 550 °C for 26 h to obtain the catalyst MgO-CeO 2 / H-ZSM-11, where the mass percentage of MgO and H-ZSM-11 is 2.5%, CeO 2 The mass percentage of H-ZSM-11 is 6.0%. Example 4

[0018] The bimetallic modified ZSM-11 zeolite catalyst of the present invention is prepared according to the following method: Step 1. Prepare H-ZSM-11 molecular sieve, the specific method is the same as Example 1; Step 2: The H-ZSM-11 molecular sieve was impregnated in a solution of calcium salt and lanthanum salt. The obtained solid was dried and calcined at 550 °C for 26 h to obtain the catalyst CaO-La 2 O 3 / H-ZSM-11, wherein the mass percentage of CaO and H-ZSM-11 is 2.5%, La 2 O 3 The mass percentage of H-ZSM-11 is 6.0%. Example 5

[0019] The bimetallic modified ZSM-11 zeolite catalyst of the present invention is prepared according to the following method: Step 1. Prepare H-ZSM-11 molecular sieve, the specific method is the same as Example 1; Step 2: The H-ZSM-11 molecular sieve was impregnated in a solution of calcium salt and cerium salt. The obtained solid was dried and calcined at 550 °C for 26 h to obtain the catalyst CaO-CeO 2 / H-ZSM-11, where the mass percentage of CaO and H-ZSM-11 is 2.5%, CeO 2 The mass percentage of H-ZSM-11 is 6.0%.

[0020] Comparative Example 1: Synthesis of HZSM-5 One-time Loaded Bimetallic Catalyst Step 1. Prepare H-ZSM-5 molecular sieve. The specific method is basically the same as Example 1, except that the template agent is changed to tetrapropylammonium hydroxide to prepare H-ZSM-5 molecular sieve; Step 2. Impregnate the H-ZSM-5 molecular sieve in a magnesium salt and cerium salt solution, and the rest is the same as step 2 of Example 1 to obtain the catalyst MgO-CeO 2 / H-ZSM-5.

[0021] Comparative Example 2: Synthesis of HZSM-5 continuously loaded bimetallic catalyst Step 1. Prepare H-ZSM-5 molecular sieve according to step 1 of comparative example 1; Step 2. According to step 2 of Example 2, HZSM-5 is substituted for HZSM-11 to prepare the catalyst MgO-La 2 O 3 / H-ZSM-5.

[0022] Comparative Example 3: HZSM-11 catalyst prepared according to step 1 of Example 1.

[0023] Application Example 1: Catalytic Reaction Performance Evaluation The reactivity of the catalytic ethylbenzene ethanol alkylation reaction in Examples 1 to 5 in a continuous fixed bed reactor was determined.

[0024] The specific operation process is as follows: the reaction temperature is 365 °C, the reaction time is 12 h, the reaction pressure is 1.5 atm, and the molar ratio of the raw material liquid is n (Ethylbenzene): n (ethanol) = 2:1, the catalyst is loaded to maintain a weight hourly space velocity WHSV = 2.0. The specific reaction results of Examples 1-5 are shown in Table 1, and the specific reaction results of Comparative Examples 1-3 are shown in Table 3.

[0025] Table 1 Reaction results of ethylbenzene ethanol in Examples 1 to 5

[0026] Table 2 Reaction results of comparative examples 1-3 ethylbenzene ethanol

[0027] Application Example 2: Catalytic Reaction Performance Evaluation The reactivity of the catalytic alkylation reaction of ethylbenzene prepared in Example 1 in a continuous fixed bed reactor was determined.

[0028] The specific operation process is as follows: the reaction temperature is 365 °C, the reaction time is 12 h, the reaction pressure is 1.5 atm, and the molar ratio of the raw material liquid is n (Ethylbenzene): n(ethylene) = 2:1, the catalyst is loaded to maintain a weight hourly space velocity WHSV = 2.0. The specific reaction results of Example 1-2 ethylstyrene are shown in Table 2, and the specific reaction results of Comparative Example 1-3 are shown in Table 3.

[0029] Table 3 Reaction results of Example 1-2 ethylbenzene

[0030] Application Example 3: Evaluation of the Alkylation Reaction Performance of Ethylbenzene and Ethanol after Catalyst Regeneration The catalyst MgO-La was prepared according to the method described in Example 1 2 O 3 / H-ZSM-11, and then the reaction activity of the alkylation reaction in the continuous fixed bed reactor was determined according to the method of Application Example 1. When the reaction reached the catalyst deactivation, the deactivated catalyst was calcined at 500 °C for 12 h until the catalyst as a whole recovered to its original color. Then, the reaction activity of the regenerated catalyst in the catalytic ethylbenzene / ethylene alkylation reaction was determined according to Application Example 1. The results are shown in Table 4.

[0031] Table 4 Reaction results after catalyst regeneration in Example 1

[0032] The experimental results show that the catalysts of Examples 1-5 of the present invention have the highest catalytic activity in the ethylbenzene ethanol / ethylene alkylation, which is much better than the ZSM-5 zeolite catalyst. The catalyst modified by one step of loading metal oxide has the best catalytic activity.

Claims

1. A bimetallic modified ZSM-11 zeolite catalyst, characterized in that: Two metal oxides MO are loaded on H-ZSM-11 molecular sieve x -M'O x , named MO x -M'O x / H-ZSM-11, wherein M is Mg or Ca, M' is La or Ce, x is 1-3, and MO x The mass percentage of H-ZSM-11 is 1.5-4.0%, and the M'O x The mass percentage of H-ZSM-11 is 3.0-7.5%.

2. A method for preparing a bimetallic modified ZSM-11 zeolite catalyst as claimed in claim 1, characterized in that Follow these steps: Step 1. preparing H-ZSM-11 molecular sieve; Step 2: Metal salts were loaded onto H-ZSM-11 molecular sieves by impregnation, and the obtained solid was calcined to obtain bimetallic modified catalyst MO. x -M'O x / H-ZSM-11.

3. The method for preparing the bimetallic modified ZSM-11 zeolite catalyst according to claim 2, characterized in that The step 1 is to mix 30 wt% silica sol, sodium metaaluminate, tetrabutylammonium bromide, Na2O and water, crystallize at 80-200°C for 5-120h, wash and dry, and then roast at 400-650°C for 4-48h to obtain NaZSM-11 matrix; the NaZSM-11 matrix is ​​mixed with an ammonium nitrate solution and then allowed to stand, the solid obtained after filtration is dried, and then calcined at 200-650° C. for 4-120 h to obtain a HZSM-11 catalyst.

4. The method for preparing the bimetallic modified ZSM-11 zeolite catalyst according to claim 3, characterized in that The step 2 is to immerse the H-ZSM-11 molecular sieve in two metal salt solutions of M-M', and then dry the obtained solid and calcine it at 500-600° C. for 4-48 hours.

5. The method for preparing the bimetallic modified ZSM-11 zeolite catalyst according to claim 3, characterized in that The step 2 is to first immerse the H-ZSM-11 molecular sieve in a metal salt solution of M, and then dry the obtained solid and calcine it at 500-600 ° C for 4-48 h to obtain the product MO x / H-ZSM-11; then the product MO x / H-ZSM-11 is impregnated in a M' metal salt solution, and the obtained solid is dried and calcined at 500-600 °C for 4-48 h.

6. Use of the bimetallic modified ZSM-11 zeolite catalyst as claimed in claim 1 in the alkylation of ethylbenzene to prepare p-diethylbenzene.

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