Preparation method of molecular sieve catalyst for liquid phase alkylation of high concentration ethylene and benzene

Abstract

The present invention provides a method for preparing a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene and benzene, and belongs to the field of molecular sieve catalysts. The preparation method of the catalyst is: kneading a binder and a Beta molecular sieve raw powder into a mold, drying, and then heat-treating in the steam of a mixed aqueous solution of ammonia and imidazole, and further drying, roasting, acidifying and roasting to obtain the required HBetaA molecular sieve catalyst; and then applying it to the liquid-phase alkylation process of high-concentration ethylene and benzene. The high-concentration ethylene contains 60-99% v of ethylene, 0.1-0.5% v of hydrogen, 0.1-0.5% v of nitrogen, 0.1-0.2% v of COx, 0.1-0.5% v of methane, 0.1-25% v of ethane, 0.1-20% v of propane, and 0.1-20% v of butane. Compared with conventional catalysts, the catalyst prepared by the method has higher stability for the liquid-phase alkylation reaction of benzene absorbing high-concentration ethylene.

Description

Technical Field

[0001] The invention belongs to the field of molecular sieve catalysts, and in particular relates to a method for preparing a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene and benzene. Background Art

[0002] Ethylbenzene is an important organic chemical raw material, mainly used in the production of styrene. At present, ethylbenzene is mainly produced by gas phase method and liquid phase method. Based on the excellent performance of molecular sieve, molecular sieve has replaced the traditional AlCl3 and become the mainstream catalyst system for the production of ethylbenzene by gas phase method and liquid phase method. Mobil and Badger Company jointly developed the pure ethylene gas phase process using high silicon ZSM-5 molecular sieve as catalyst in the 1970s (F.Dwyer.Manufacture of ethylbenzene.USP 4107224,1978), and realized industrialization in the United States in 1980. In the 1980s, Dalian Institute of Chemical Physics, Fushun Oil Plant No. 2 and Sinopec developed a catalyst for catalytic cracking dry gas to ethylbenzene, and developed a new rare earth-ZSM-5 / ZSM-11 co-crystallized molecular sieve catalyst for the first time, and developed a gas-phase dry gas to ethylbenzene process (Wang Qingxia; Zhang Shurong; Cai Guangyu; Wei Yongzhen; Li Feng; Huang Zuxian, Process for preparing ethylbenzene by alkylation of dilute ethylene and the zeolite catalyst used, ZL87105054.4, 1993). Recently, Shanghai Research Institute of Petrochemical Technology has also successfully developed a ZSM-5 molecular sieve catalyst and process for the gas-phase synthesis of ethylbenzene (Sun Hongmin; Yang Weimin; Zhang Bin; Huan Mingyao, Method for producing ethylbenzene by reacting pure ethylene or dry gas with benzene, ZL 200910201666.2, 2014).

[0003] The reaction temperature of liquid phase alkylation to produce ethylbenzene is low (generally <300°C), and there are fewer by-products, especially the xylene impurity content (<100ppm) is much lower than that of the gas phase method. In addition, the liquid phase method also has the advantages of easy control of operating temperature and long catalyst life. Due to the low operating temperature, the diffusion of reactants in the micropores of the molecular sieve is slow, so molecular sieves with larger pores are often used in the liquid phase alkylation method, such as BEA (Beta), FAU (Y) and MWW (MCM-22, MCM-49 and MCM-56, etc.) molecular sieves. The molecular sieves currently used in industrial production include Y, MCM-22 and Beta molecular sieves.

[0004] In the 1980s, Unocal, Lummus and UOP in the United States jointly developed a liquid phase process for the production of ethylbenzene from benzene and ethylene using USY molecular sieve as a catalyst, and built the first industrial production unit in Oita, Japan in 1990. Compared with the Y molecular sieve catalyst, the Beta molecular sieve catalyst developed by Chevron in the early 1990s has higher catalytic activity and ethylbenzene selectivity (RA Innes, SI Zones, GJ Nacamuli, Liquid phase alkylation or transalkylation process using zeolite BETA, USP 4891458, 1990). Sinopec Research Institute of Petrochemical Technology developed the Beta molecular sieve-γ-alumina catalyst and used it in the ethylbenzene synthesis process (Huang Zhiyuan; Tian Suxian; Xu Yali; Zhu Bin; Wang Weidong; Zhang Fengmei, β zeolite-γ-alumina catalyst and its preparation method, ZL93106946.7, 1998). Cheng et al. (J. Cheng, T. Degnan, J. Beck, et al. Stud. Surf. Sci. Catal., 1999, 121: 53) compared the catalytic performance of Y, Beta and MCM-22 molecular sieves in the process of studying the liquid phase alkylation reaction of benzene and ethylene, and found that Beta molecular sieve had the highest activity, while MCM-22 molecular sieve had the highest selectivity for monoalkylation reaction.

[0005] Traditional ethylene production comes from the cracking of petroleum hydrocarbons. Initially, ethane and propane recovered from natural gas were used as raw materials. However, with the rapid increase in demand for olefins, ethane and propane alone cannot meet market demand. Cracking raw materials are developing towards heavy materials, such as naphtha, kerosene, light diesel and heavy diesel. With the reduction of petroleum resources, non-petroleum resource production routes for ethylene have begun to attract attention, such as coal-based methanol to low-carbon olefins, ethane in shale gas to ethylene, etc. The utilization of high-concentration ethylene obtained by separation of these olefin mixed hydrocarbon gases has attracted more and more attention. For example, the olefin mixture obtained by high-temperature cracking of C2-C4 alkanes can be separated to obtain a mixed hydrocarbon with >45% ethylene (the rest is methane, ethane and propylene, etc.).

[0006] For the utilization of this part of olefins, the first way is to obtain pure ethylene through deep cold separation, but the energy consumption is high; the second way is the gas phase reaction of benzene and ethylene, but the xylene content in the product is high; the third way is the direct liquid phase alkylation of benzene and high concentration ethylene. Since the alkanes cannot be completely dissolved in benzene, this can easily cause voiding (gas-liquid phase caused by the escape of inert gas, which is a phenomenon in which the catalyst is placed in the gas phase for a short time) and thus shorten the catalyst life; the fourth way is the alkylation of benzene absorbing high concentration ethylene in liquid phase combined with the gas phase method. Benzene absorption high concentration ethylene liquid phase alkylation is the reverse adsorption of benzene with olefin mixture obtained by high temperature cracking of C2-C4 alkanes under higher pressure (2.0-3.0MPa) to obtain a benzene mixture of C1-C4 hydrocarbons with higher concentration of ethylene, which enters the liquid phase reactor for liquid phase alkylation at higher pressure (3.5-5.0MPa) and normal reaction temperature (180-260°C). During the reaction, alkanes and olefins are dissolved in benzene and mixed aromatic hydrocarbons of the product without escape, which will not cause cavitation. The life of the catalyst and product quality are better than the third method. The catalyst involved in this patent application is mainly for the fourth method. In the liquid phase alkylation reaction of high concentration ethylene and benzene, the HBetaA catalyst prepared by the present invention has better stability than the conventional one while maintaining similar initial reaction activity. Summary of the invention

[0007] The purpose of the present invention is to develop a method for preparing a molecular sieve catalyst for liquid phase alkylation of high-concentration ethylene by benzene absorption. The HBetaA catalyst prepared by the method has better stability in the liquid phase alkylation reaction of high-concentration ethylene and benzene than the conventional one. The present invention is simple and easy to operate and has strong practicality. The catalyst prepared by the present invention is named HBetaA molecular sieve catalyst.

[0008] The present invention provides a method for preparing a molecular sieve catalyst for liquid phase alkylation of benzene absorbing high-concentration ethylene, which is specifically as follows:

[0009] (1) kneading Beta molecular sieve raw powder and a binder into a mold and drying; wherein the weight content of Beta is 65% to 85%, the weight content of the binder is 15% to 35%, and the binder is derived from one or both of alumina and silica;

[0010] (2) placing the molded and dried sample in the steam of a mixed aqueous solution of ammonia water and IMD for heat treatment, wherein the weight ratio of ammonia water to the dry weight of the molded sample is 1.2%-6.0%, and the weight of IMD to the dry weight of the molded sample is 1.0%-5.0%; the temperature is 60-150° C., and the time is 5-20 hours;

[0011] (3) The hydrothermally treated sample is dried and calcined, wherein the drying temperature is 120-150°C, the calcination temperature is 450-600°C, and the calcination time is 5-10 h. Then it is acidified with oxalic acid, with a concentration of 0.1-0.2N, a liquid-solid ratio of 4-6, a temperature of 60-80°C, a time of 1-2 h, a calcination temperature of 400-500°C, and a calcination time of 1-2 h, and calcination is performed to obtain HBetaA molecular sieve catalyst.

[0012] The present invention provides a method for preparing a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene and benzene. The HBetaA catalyst is applied to the liquid-phase alkylation process of high-concentration ethylene and benzene. The reaction conditions are 180-260°C, 30-50 atm, and ethylene weight space velocity: 0.1-0.8 h -1 , benzene / ethylene molar ratio is 10 to 30. The high concentration ethylene contains 60 to 99% v of ethylene, 0.1 to 0.5% v of hydrogen, 0.1 to 0.5% v of nitrogen, 0.1 to 0.2% v of COx, 0.1 to 0.5% v of methane, 0.1 to 25% v of ethane, 0.1 to 20% v of propane, 0.1 to 20% v of butane, etc.

[0013] The raw material benzene used in the present invention is industrial pure benzene, or a mixture of benzene and ethylene and benzene hydrocarbonation products. The concentrated ethylene raw gas comes from the cracking of petroleum hydrocarbons, naphtha, kerosene, light diesel and heavy diesel, and can also come from coal-based methanol to low-carbon olefins, ethane in shale gas to ethylene, etc. Benzene needs to be dehydrated (<50ppm) and de-alkali nitrogen (<50ppm); the concentrated ethylene raw gas needs to be purified, such as desulfurization (<50ppm), dehydration (<50ppm) and de-organic alkali nitrogen (<50ppm), etc. The high-concentration ethylene contains 60-99% v of ethylene, 0.1-0.5% v of hydrogen, 0.1-0.5% v of nitrogen, 0.1-0.5% v of COx, 0.1-0.2% v of methane, 0.1-0.5% v of ethane, 0.1-25% v of propane, 0.1-20% v of butane, etc. Wherein COx represents the sum of CO and CO2.

[0014] The catalyst provided by the present invention is a mixture of Beta molecular sieve raw powder containing a template with amorphous alumina and / or a silica binder, which is subjected to hydrothermal treatment in steam containing ammonium and IMD after molding and drying, and then dried, calcined, acidified and calcined to obtain the desired HBetaA catalyst. The molecular sieve catalyst prepared by the present invention has high crystallinity and a simple preparation process. The method provided by the present invention utilizes the synergistic effect of ammonium and IMD on the Beta molecular sieve catalyst containing a template (Comparative Examples 1-3 and Example 1), and solves the problem that the binder dilutes the crystallinity and destroys the structure of the molecular sieve, thereby affecting the diffusion of reactants and products in the catalyst and promoting the reaction activity of the catalyst.

[0015] Beneficial effects of the present invention:

[0016] Compared with the samples obtained by traditional methods, the HBetaA catalyst prepared by the patented method has better reaction stability when used in the liquid phase alkylation reaction of high-concentration ethylene and benzene while maintaining similar initial reaction activity. DETAILED DESCRIPTION

[0017] The present invention will be further described in the following examples, but the present invention is not limited thereto.

[0018] Comparative Example 1

[0019] Weigh 10 grams of Beta molecular sieve powder (Na2O: 0.15% W, dry basis 80% W, the same below), add 1.62 grams of alumina (dry basis 87% W, the same below) and mix, extrude and shape, and dry at 120°C to obtain sample A. A mixture of 1.8 grams of ammonia water (26% W, the same below) and 30 grams of distilled water was added to the reactor in advance, and sample A was placed on the porous stainless steel mesh in the reactor and sealed, and then gas-solid phase treatment was carried out at 120°C for 10 hours. After the product was taken out, it was washed with water twice, dried at 120°C for 2h, and roasted at 500°C for 5h, followed by oxalic acid acidification, with a concentration of 0.1N, a liquid-solid ratio of 4, a temperature of 60°C, a time of 2h, a roasting temperature of 400°C, and a roasting time of 2h. The obtained catalyst is recorded as Cat-A. XRF results showed that the Na2O content of Cat-A sample was <0.05%W and the RC of Cat-A was 82%.

[0020] Taking the XRD diffraction characteristic peak of the template Beta removed as the benchmark, it is defined as 100%, and the ratio of the diffraction peak intensity of other samples to the XRD diffraction peak intensity of the corresponding Beta content (template removed) of the sample is the relative crystallinity (RC). For example, the RC (82%) of Cat-A in Comparative Example 1 is the diffraction peak intensity of the Cat-A sample in Comparative Example 1 / (85% of the diffraction peak intensity of the template Beta removed, 85% is Beta:Al2O3=85:15W / W in the Cat-A sample).

[0021] Comparative Example 2

[0022] Weigh 10 grams of Beta molecular sieve powder, add 1.62 grams of alumina and mix, extrude and shape, dry at 120℃ to obtain sample A. A mixture of 0.29 grams of imidazole (IMD,>99%, the same below) and 30 grams of distilled water was added to the reactor in advance, and sample A was placed on the porous stainless steel mesh in the reactor and sealed, and then gas-solid phase treatment was carried out at 120℃ for 10 hours. After the product was taken out, it was washed with water twice, dried at 120℃ for 2h, and roasted at 500℃ for 5h, followed by oxalic acid acidification, with a concentration of 0.1N, a liquid-solid ratio of 4, a temperature of 60℃, a time of 2h, a roasting temperature of 400℃, and a roasting time of 2h. The obtained catalyst was recorded as Cat-B. XRF results show that the Na2O content of Cat-B sample is 0.10%W. The RC of Cat-B is 85%.

[0023] Comparative Example 3

[0024] Weigh 8 grams of Beta molecular sieve without template agent, add 1.62 grams of alumina and mix, extrude and dry at 120℃ to obtain sample B. A mixture of 1.8 grams of ammonia water, 0.29 grams of IMD and 30 grams of distilled water was added to the reactor in advance, and sample B was placed on the porous stainless steel mesh in the reactor and sealed, and then gas-solid phase treatment was carried out at 120℃ for 10 hours. After the product was taken out, it was washed with water twice, dried at 120℃ for 2 hours, and roasted at 500℃ for 5 hours, followed by oxalic acid acidification, with a concentration of 0.1N, a liquid-solid ratio of 4, a temperature of 60℃, a time of 2 hours, a roasting temperature of 400℃, and a roasting time of 2 hours. The obtained catalyst was recorded as Cat-C. XRF results show that the Na2O content of the Cat-C sample is <0.05%W. The RC of Cat-C is 86%.

[0025] Example 1

[0026] Weigh 10 grams of Beta molecular sieve powder, add 1.62 grams of alumina and mix, extrude and shape, dry at 120℃ to obtain sample A. A mixture of 1.8 grams of ammonia water, 0.29 grams of IMD and 30 grams of distilled water was added to the reactor in advance, and sample A was placed on the porous stainless steel mesh in the reactor and sealed, and then gas-solid phase treatment was carried out at 120℃ for 10 hours. After the product was taken out, it was washed with water twice, dried at 120℃ for 2 hours, and roasted at 500℃ for 5 hours, followed by oxalic acid acidification, with a concentration of 0.1N, a liquid-solid ratio of 4, a temperature of 60℃, a time of 2 hours, a roasting temperature of 400℃, and a roasting time of 2 hours. The obtained catalyst was recorded as Cat-D. XRF results show that the Na2O content of the Cat-D sample is <0.05%W. The RC of Cat-D is 100%.

[0027] Example 2

[0028] Weigh 7.64 g of Beta molecular sieve powder, add 2.63 g of alumina and 1 g of silicon oxide powder (>99%), mix, extrude and shape, and dry at 120°C to obtain sample C. A mixture of 0.44 g of ammonia water, 0.10 g of IMD and 30 g of distilled water was added to the reactor in advance, and sample C was placed on the porous stainless steel mesh in the reactor and sealed, and then subjected to gas-solid phase treatment at 60°C for 20 hours. After the product was taken out, it was washed with water twice, dried at 150°C for 2h, and roasted at 450°C for 10h, followed by oxalic acid acidification, with a concentration of 0.2N, a liquid-solid ratio of 6, a temperature of 80°C, a time of 1h, a roasting temperature of 500°C, and a roasting time of 1h. The obtained catalyst was recorded as Cat-E. XRF results show that the Na2O content of the Cat-E sample is <0.05%W. The RC of Cat-E is 126%.

[0029] Example 3

[0030] Weigh 9.4 grams of Beta molecular sieve powder, add 2.16 grams of alumina and mix, extrude and shape, dry at 130°C to obtain sample D. A mixture of 2.2 grams of ammonia water, 0.48 grams of IMD and 30 grams of distilled water was added to the reactor in advance, and sample D was placed on the porous stainless steel mesh in the reactor and sealed, and then subjected to gas-solid phase treatment at 150°C for 5 hours. After the product was taken out, it was washed with water twice, dried at 150°C for 2 hours, and roasted at 600°C for 7 hours, followed by oxalic acid acidification, with a concentration of 0.15N, a liquid-solid ratio of 5, a temperature of 70°C, a time of 1.5 hours, a roasting temperature of 450°C, and a roasting time of 1.5 hours. The obtained catalyst was recorded as Cat-F. XRF results show that the Na2O content of the Cat-F sample is <0.05%W. The RC of Cat-F is 109%.

[0031] Comparative Examples 1 to 3 and Examples 1 to 3 Reaction Evaluation

[0032] The catalysts obtained in Comparative Examples 1 to 3 and Examples 1 to 3 were placed in a fixed bed reactor with an inner diameter of 16 mm and continuous flow for catalyst performance evaluation. The loading amount of the catalyst was 5 g. The temperature was raised to 420 ° C for activation for 1 hour in a N2 atmosphere, and then dropped to the reaction temperature in a N2 atmosphere. The raw materials were purified qualified high-concentration ethylene and benzene. The product after the reaction was cooled by a cooler for gas-liquid separation. The gas and liquid products were analyzed for composition using an Agilent 7890A chromatography system. The ethylene conversion rate of the reaction for 20 hours was defined as the initial activity, and the change in the ethylene conversion rate of the reaction to 240 hours and the ethylene conversion rate of 20 hours was defined as the stability of the catalyst.

[0033] The composition of the raw material benzene used (%w): benzene: 99.900; toluene: 0.095; others: 0.005. The composition of the concentrated ethylene raw gas is shown in Table 1. The liquid phase alkylation reaction conditions and results are shown in Table 2.

[0034] The reaction performance of the catalysts is shown in Table 2. The ethylation selectivity in the reaction products of all catalysts was greater than 99.7% during the reaction. The ethylene conversion rate of the Cat-B catalyst was the lowest at 20h, which was only 90.00%, which may be due to the high amount of Na2O contained in the sample, resulting in a low acid content of the catalyst. The ethylene conversion rate of other catalysts did not change significantly at 20h, >99%, but when the reaction was carried out to 240h, the ethylene conversion rates of the Beta molecular sieve catalyst containing the template agent only treated with ammonia water to obtain Cat-A, and the Beta molecular sieve catalyst without the template agent treated with ammonia water and IMD to obtain Cat-C were 90.14% and 92.62%, respectively, while the ethylene conversion rates of the catalysts (Cat-D, Cat-E, Cat-F) prepared by treating the Beta molecular sieve catalyst containing the template agent with ammonia water and IMD were maintained above 99%. We speculate that there is a synergistic effect between ammonia and IMD treatment of Beta zeolite catalyst containing template, while the synergistic effect is not obvious for Beta zeolite catalyst without template, which can be supported by the RC of XRD of the sample. As a result, the stability of the catalysts is different, and the specific reasons need further investigation.

[0035] Table 1 Composition of concentrated ethylene feed gas (% v)

[0036] raw material <![CDATA[H2]]> <![CDATA[N2]]> <![CDATA[CO x ]]> <![CDATA[CH4]]> <![CDATA[C2H4]]> <![CDATA[C2H6]]> <![CDATA[C3H8]]> <![CDATA[C4H 10 ]]> I 0.1 0.2 0.1 0.3 74.3 24.8 0.1 0.1 II 0.3 0.5 0.2 0.5 60.0 10.0 9.0 19.5 III 0.5 0.4 0.2 0.1 70.0 4.0 19.0 5.8 IV 0.2 0.3 0.1 0.2 98.4 0.2 0.5 0.1

[0037] Table 2 Catalytic reaction evaluation results of catalysts

[0038]

[0039] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a molecular sieve catalyst for liquid phase alkylation of high concentration ethylene and benzene, the preparation method being as follows: (1) kneading Beta molecular sieve raw powder and a binder into a mold and drying; wherein the weight content of the Beta molecular sieve raw powder is 65% to 85%, the weight content of the binder is 15% to 35%, and the binder is derived from one or both of aluminum oxide and silicon oxide; (2) placing the formed and dried sample in the steam of a mixed aqueous solution of ammonia and imidazole for heat treatment at a temperature of 60 to 150° C. for a time of 5 to 20 hours; (3) drying, calcining for the first time, acidifying and calcining for the second time the treated sample to obtain HBetaA molecular sieve catalyst; The drying temperature of step (3) is 120-150°C; the first roasting temperature is 450-600°C, and the roasting time is 5-10 h; the acidulant used in step (3) is oxalic acid, with a concentration of 0.1-0.2N, a liquid-solid ratio of 4-6, a temperature of 60-80°C, and an acidification time of 1-2 h; the second roasting temperature is 400-500°C, and the roasting time is 1-2 h.

2. A method for preparing a molecular sieve catalyst for liquid phase alkylation of high concentration ethylene and benzene according to claim 1, characterized in that : In step (2), the weight ratio of the ammonia water to the sample dry basis after molding and drying is 1.2% - 6.0%, and the weight of imidazole is 1.0% - 5.0% of the sample dry basis weight after molding.

3. A HBetaA molecular sieve catalyst prepared by the method according to any one of claims 1 to 2.

4. An application of the molecular sieve catalyst according to claim 3, characterized in that: HBetaA catalyst is used in the liquid phase alkylation process of high concentration ethylene and benzene.

5. The use according to claim 4, characterized in that: Reaction conditions: 180~260℃, 30~50atm, ethylene weight space velocity: 0.1~0.8 h -1 , the benzene / ethylene molar ratio is 10~30.

6. The use according to claim 4, characterized in that: The high concentration ethylene contains 60-99% v of ethylene, 0.1-0.5% v of hydrogen, 0.1-0.5% v of nitrogen, 0.1-0.2% v of COx, 0.1-0.5% v of methane, 0.1-25% v of ethane, 0.1-20% v of propane, and 0.1-20% v of butane, wherein COx represents the sum of CO and CO2.

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