CN115869990A - Preparation method of high-concentration ethylene and benzene liquid-phase alkylation molecular sieve catalyst - Google Patents

Abstract

The invention provides a preparation method of a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene and benzene, belonging to the field of molecular sieve catalysts. The preparation method of the catalyst comprises the following steps: mixing and kneading the binder and Beta molecular sieve raw powder, molding, drying, then performing heat treatment in steam of mixed aqueous solution of ammonia water and imidazole, and further performing drying, roasting, acidification and roasting to obtain the required HBetaA molecular sieve catalyst; it is then applied to a high concentration ethylene and benzene liquid phase alkylation process. High-concentration ethylene containing ethylene 60-99% v, hydrogen 0.1-0.5% v, nitrogen 0.1-0.5% v, COx0.1-0.2% v, methane 0.1-0.5% v, ethane 0.1-25% v, propane 0.1-20% v, and butane 0.1-20% v. Compared with the conventional catalyst, the catalyst prepared by the method has higher stability for the liquid-phase alkylation reaction of the benzene-absorbed high-concentration ethylene.

Description

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

Technical Field

The invention belongs to the field of molecular sieve catalysts, and particularly relates to a preparation method of a liquid-phase alkylated molecular sieve catalyst for high-concentration ethylene and benzene.

Background

Ethylbenzene is an important organic chemical raw material and is mainly used for producing styrene. At present, the ethylbenzene production mainly comprises a gas phase method and a liquid phase method. Based on the excellent performance of the molecular sieve, the conventional AlCl is replaced by the molecular sieve ₃ The catalyst system becomes the mainstream catalyst system for producing the ethylbenzene by a gas phase method and a liquid phase method. The Mobil and Badger company collaborated in the seventies of the last century to develop a pure ethylene gas phase process (f.dwyer. Manual of ethyl benzene. Usp 4107224,1978) using a high-silicon ZSM-5 molecular sieve as a catalyst and was industrialized in the united states in 1980. In the last 80 th century, a university chemical and physical research institute, a Fushun petroleum II plant and a China general petrochemical company collaborate to develop a catalyst for preparing ethylbenzene by catalytic cracking dry gas, firstly develops a novel rare earth-ZSM-5/ZSM-11 cocrystallization molecular sieve catalyst, and develops a process for preparing ethylbenzene by gas phase dry gas (Wang Qingxia; zhang Shurong; cai Guangyu; wei Yongzhen; li Feng; huang Zuxian, a process for preparing ethylbenzene by alkylation of dilute ethylene and a zeolite catalyst used in the process, namely ZL87105054.4,1993). Recently, shanghai institute of Petroleum and chemical Engineers has also developed a ZSM-5 molecular sieve catalyst and process for the successful gas phase synthesis of ethylbenzene (Sun Hongmin; yang Min; zhang Bin; huan Mingyao, ZL 200910201666.2,2014, a method for producing ethylbenzene by the reaction of pure ethylene or dry gas with benzene).

The reaction temperature for preparing ethylbenzene by alkylation in a liquid phase method is lower (generally less than 300 ℃), the byproducts are less, and especially the impurity content of dimethylbenzene (< 100 ppm) is far lower than that of a gas phase method. In addition, the liquid phase method also has the advantages of easy control of the operation temperature, long service life of the catalyst and the like. Due to the low operating temperature and slow diffusion of reactants in the micropores of the molecular sieve, molecular sieves with larger pore diameters, such as BEA (Beta), FAU (Y) and MWW (MCM-22, MCM-49, MCM-56, etc.) molecular sieves, are often used in liquid phase alkylation processes. Molecular sieves currently used in commercial production include Y, MCM-22 and Beta molecular sieves.

In the 80 s of the 20 th century, unocal, lummus and UOP in the United states developed a technology for producing ethylbenzene by a liquid phase method of benzene and ethylene with USY molecular sieves as catalysts, and a first industrial production device was built in Japan Oita in 1990. The Beta molecular sieve catalyst developed by Chevron corporation in the early 90 s had higher catalytic activity and ethylbenzene selectivity compared to the Y molecular sieve catalyst (R.A. Innes, S.I. Zones, G.J. Nacamuli, liquid phase alkylation or transesterification process using zeolite BETA, USP 4891458,1990). Beta molecular sieve-gamma-alumina catalyst is developed by China petrochemical engineering science research institute and used in the ethylbenzene synthesis process (Huang Zhiyuan; tian Suxian; xu Yali; zhu Bin; wang Weidong; zhang Fengmei, beta zeolite-gamma-alumina catalyst and its preparation method, ZL93106946.7,1998). Cheng et al (J.Cheng, T.Degnan, J.Beck, et al. Stud. Surf.Sci.Cat., 1999, 121).

The conventional ethylene production comes from the cracking of petroleum hydrocarbons, initially using ethane and propane recovered from natural gas as raw materials, but with the rapid increase of olefin demand, the market demand is far from being met only by using ethane and propane as cracking raw materials, and the cracking raw materials are developed to be heavy, such as naphtha, kerosene, light diesel oil and heavy diesel oil. With the decrease of petroleum resources, non-petroleum resources are attracting attention for producing ethylene, such as coal-based low-carbon olefins produced by methanol, ethylene produced by ethane in shale gas, and the like. The utilization of high-concentration ethylene obtained by separating the olefin mixed hydrocarbon gas is more and more attracting attention, for example, after the olefin mixture obtained by pyrolysis of C2-C4 alkane is separated, mixed hydrocarbon (the rest is methane, ethane, propylene and the like) with more than 45% of ethylene can be obtained.

Aiming at the utilization of the part of olefin, the first mode is to obtain pure ethylene through cryogenic separation, but the energy consumption is high; the second mode is a gas phase method reaction of benzene and ethylene, but the xylene content in the product is high; the third mode is benzene and high-concentration ethylene direct liquid phase alkylation, and because alkane can not be completely dissolved in benzene, empty flooding (gas-liquid phase state caused by inert gas escape, which is a phenomenon that a catalyst is placed in a short-time gas phase) is easily caused, so that the service life of the catalyst is shortened; the fourth mode is the liquid phase of the benzene absorption high concentration ethylene combined with the alkylation of the gas phase process. The liquid phase alkylation of the ethylene with high concentration absorbed by the benzene is that the benzene and an olefin mixture obtained by pyrolysis of C2-C4 alkane are reversely adsorbed under higher pressure (2.0-3.0 MPa) to obtain a benzene mixture of C1-C4 hydrocarbon of ethylene with higher concentration, the benzene mixture enters a liquid phase reactor to carry out liquid phase alkylation under higher pressure (3.5-5.0 MPa) and normal reaction temperature (180-260 ℃), the alkane and the olefin are both dissolved in mixed aromatic hydrocarbon of the benzene and a product without escaping in the reaction process, so that the empty flooding is not caused, the service life of the catalyst is better than that of the third mode, and the catalyst related to the application patent is mainly directed at the fourth mode. In the liquid phase alkylation reaction of high-concentration ethylene and benzene, compared with the conventional HBetaA catalyst prepared by the invention, the HBetaA catalyst has better stability on the basis of keeping similar initial reaction activity.

Disclosure of Invention

The invention aims to develop a preparation method of a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene in benzene absorption, and the HBetaA catalyst prepared by the method has better stability in liquid-phase alkylation of high-concentration ethylene and benzene compared with the conventional catalyst. The invention is simple and easy to operate, and has strong practicability. The catalyst prepared by the invention is named as HBetaA molecular sieve catalyst.

The invention provides a preparation method of a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene for benzene absorption, which comprises the following steps:

(1) Kneading Beta molecular sieve raw powder and a binder, molding and drying; wherein the Beta accounts for 65-85 wt%, the binder accounts for 15-35 wt%, and the binder is one or two of aluminum oxide and silicon oxide;

(2) Placing the molded and dried sample into steam of a mixed aqueous solution of ammonia water and IMD for heat treatment, wherein the weight ratio of the ammonia water to the dry basis of the molded sample is 1.2-6.0%, and the weight of the IMD is 1.0-5.0% of the dry basis weight of the molded sample; the temperature is 60-150 ℃, and the time is 5-20 hours;

(3) Drying and roasting the hydrothermally treated sample, wherein the drying temperature is 120-150 ℃, the roasting temperature is 450-600 ℃, the roasting time is 5-10 h, and then oxalic acid is acidified, and the concentration is as follows: 0.1 to 0.2N, the liquid-solid ratio of 4 to 6, the temperature of 60 to 80 ℃, the time of 1 to 2 hours, the roasting temperature of 400 to 500 ℃, the roasting time of 1 to 2 hours, and roasting to prepare the HBetaA molecular sieve catalyst.

The invention provides a preparation method of a molecular sieve catalyst for liquid-phase alkylation of high-concentration ethylene and benzene, which applies an HBetaA catalyst to the liquid-phase alkylation of high-concentration ethylene and benzene under the reaction conditions of 180-260 ℃, 30-50 atm and ethylene weight space velocity: 0.1 to 0.8 hour ^-1 And the molar ratio of benzene to ethylene is 10-30. The high concentration ethylene comprises 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 0.5% v of COx0.1 to 0.2% v, 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 and the like.

The raw material benzene used in the invention is industrial pure benzene, and can also be a mixture of benzene and ethylene and benzene alkylation products. The concentrated ethylene raw material gas is from cracking of petroleum hydrocarbon, naphtha, kerosene, light diesel oil and heavy diesel oil, and also from coal-based low-carbon olefin prepared by methanol, ethylene prepared by ethane in shale gas and the like. The benzene needs to be dehydrated (<50 ppm) and dealkalized nitrogen (A), (B), (C)<50 ppm); the concentrated ethylene feed gas being purified, e.g. desulphurised<50 ppm), dehydration (<50 ppm) and deorganobasic nitrogen (b)<50 ppm) and the like, high concentration ethylene content of 60 to 99% v, hydrogen 0.1 to 0.5% v, nitrogen 0.1 to 0.5% v, and COx0.1 to 0.2% v, methane 0.1 to 0.5% v, ethane 0.1 to 25% v, propane 0.1 to 20% v, butane 0.1 to 20% v, and the like. Wherein COx represents CO and CO ₂ The sum of (a) and (b).

The catalyst provided by the invention is prepared by mixing Beta molecular sieve raw powder containing a template agent with amorphous alumina andor silicon dioxide binder, carrying out hydrothermal treatment in steam containing ammonium and IMD after molding and drying, and then drying, roasting, acidifying and roasting. The molecular sieve catalyst prepared by the invention has high crystallinity and simple preparation process. The method provided by the invention utilizes the synergistic effect of ammonium and IMD (comparative examples 1-3 and example 1) on the Beta molecular sieve catalyst containing the template agent, and solves the problems that the adhesive has dilution and structure damage effects on the crystallinity of the molecular sieve, further influences the diffusion of reactants and products in the catalyst, promotes the reaction activity of the catalyst and the like.

The invention has the beneficial effects that:

compared with the sample obtained by the traditional method, the HBetaA catalyst prepared by the method has better reaction stability when being used in the liquid phase alkylation reaction of high-concentration ethylene and benzene on the basis of keeping similar initial reaction activity.

Detailed Description

The following examples further illustrate the invention but are not intended to limit the invention thereto.

Comparative example 1

Weighing 10 g of Beta raw powder molecular sieve (Na) ₂ 0.15% by weight, 80% by weight on a dry basis, the same below), 1.62 g of alumina (87% by weight on a dry basis, the same below) was added and mixed, and then extrusion-molded, followed by drying at 120 ℃ to obtain sample A. A mixture of 1.8 g of aqueous ammonia (26% by weight, the same applies hereinafter) and 30 g of distilled water was preliminarily charged into a reaction vessel, and sample A was sealed above a porous stainless steel net in the reaction vessel and then subjected to gas-solid phase treatment at 120 ℃ for 10 hours. After the product is taken out, the product is washed for 2 times by water, dried for 2 hours at 120 ℃, roasted for 5 hours at 500 ℃, and then acidified by oxalic acid with the concentration: 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, wherein the obtained catalyst is marked as Cat-A. XRF results showed Na for Cat-A samples ₂ Content of O<0.05% by weight of W, the RC of Cat-A is 82%.

Based on the characteristic peak of XRD diffraction of Beta without template agent, the Relative Crystallinity (RC) is defined as 100%, the ratio of the diffraction peak intensity of other samples to the diffraction peak intensity of the XRD diffraction peak of Beta (without template agent) with corresponding content of the sample is RC, for example, RC (82%) of Cat-A in comparative example 1 is the diffraction peak intensity of Cat-A sample in comparative example 1/(85% of diffraction peak intensity of Beta without template agent, 85% is Beta: al in Cat-A sample ₂ O ₃ ＝85:15W/W)。

Comparative example 2

Weighing 10 g of Beta raw powder molecular sieve, adding 1.62 g of alumina, mixing, extruding, and drying at 120 ℃ to obtain a sample A. 0.29 g of imidazole (IMD,>99%, the same applies hereinafter) and 30 g steamDistilling the mixture of water, placing the sample A in a reaction kettle above a porous stainless steel net for sealing, and then carrying out gas-solid phase treatment for 10 hours at 120 ℃. The product was taken out, washed 2 times with water, dried at 120 ℃ for 2h, and calcined at 500 ℃ for 5h, followed by oxalic acid acidification at the concentration: 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, wherein the obtained catalyst is marked as Cat-B. XRF results show Na for Cat-B samples ₂ O content 0.10% w. The RC of Cat-B was 85%.

Comparative example 3

Weighing 8 g of Beta molecular sieve without the template, adding 1.62 g of alumina, mixing, extruding, molding, and drying at 120 ℃ to obtain a sample B. A mixture of 1.8 g of ammonia, 0.29 g of IMD and 30 g of distilled water was added to the reaction vessel, and the sample B was sealed above a porous stainless steel net in the reaction vessel and then subjected to gas-solid phase treatment at 120 ℃ for 10 hours. The product was taken out, washed 2 times with water, dried at 120 ℃ for 2h, and calcined at 500 ℃ for 5h, followed by oxalic acid acidification at the concentration: 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, wherein the obtained catalyst is marked as Cat-C. XRF results showed Na for Cat-C samples ₂ O content<0.05% by weight of W. RC of Cat-C was 86%.

Example 1

Weighing 10 g of Beta raw powder molecular sieve, adding 1.62 g of alumina, mixing, extruding, molding, and drying at 120 ℃ to obtain a sample A. A mixture of 1.8 g of ammonia, 0.29 g of IMD and 30 g of distilled water was added to the reaction vessel, and the sample A was sealed above a porous stainless steel net in the reaction vessel and then subjected to gas-solid phase treatment at 120 ℃ for 10 hours. The product was taken out, washed 2 times with water, dried at 120 ℃ for 2h, and calcined at 500 ℃ for 5h, followed by oxalic acid acidification at the concentration: 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, wherein the obtained catalyst is marked as Cat-D. XRF results showed Na for Cat-D samples ₂ Content of O<0.05% by weight of W. RC of Cat-D is 100%.

Example 2

Weighing 7.64 g of Beta raw powder molecular sieve, 2.63 g of alumina and 1 g of silica powder (A), (B) are added>99%) and then extrusion moldingAnd drying at 120 ℃ to obtain a sample C. A mixture of 0.44 g of ammonia, 0.10 g of IMD and 30 g of distilled water was preliminarily added to the reaction vessel, and the sample C was sealed above a porous stainless steel net in the reaction vessel and then subjected to gas-solid phase treatment at 60 ℃ for 20 hours. The product was taken out, washed 2 times with water, dried at 150 ℃ for 2h, and calcined at 450 ℃ for 10h, followed by oxalic acid acidification at the concentration: 0.2N, the liquid-solid ratio is 6, the temperature is 80 ℃, the time is 1h, the roasting temperature is 500 ℃, the roasting time is 1h, and the obtained catalyst is marked as Cat-E. XRF results showed Na for Cat-E samples ₂ Content of O<0.05% by weight of W. The RC of Cat-E was 126%.

Example 3

Weighing 9.4 g of Beta raw powder molecular sieve, adding 2.16 g of alumina, mixing, extruding, molding, and drying at 130 ℃ to obtain a sample D. A mixture of 2.2 g of ammonia, 0.48 g of IMD and 30 g of distilled water was added to the reaction vessel, and the sample D was sealed above a porous stainless steel mesh in the reaction vessel and subjected to gas-solid phase treatment at 150 ℃ for 5 hours. After the product is taken out, the product is washed for 2 times by water, dried for 2h at 150 ℃, roasted for 7h at 600 ℃, and then acidified by oxalic acid with the concentration: 0.15N, a liquid-solid ratio of 5, a temperature of 70 ℃, a time of 1.5h, a calcination temperature of 450 ℃, and a calcination time of 1.5h, wherein the obtained catalyst is named Cat-F. XRF results show Na for Cat-F samples ₂ Content of O<0.05% by weight of W. The RC of Cat-F was 109%.

Comparative examples 1 to 3 and examples 1 to 3 reaction evaluation

The catalysts obtained in comparative examples 1 to 3 and examples 1 to 3 were placed in a continuous flow fixed bed reactor having an inner diameter of 16mm, respectively, to evaluate the performance of the catalyst, and the loading of the catalyst was 5g in N ₂ Heating to 420 ℃ under the atmosphere for activation for 1h, and then activating in N ₂ The atmosphere is reduced to the reaction temperature, and the raw materials are high-concentration ethylene and benzene which are qualified after purification. And cooling the product after reaction by a cooler for gas-liquid separation. Both gaseous and liquid products were analyzed for composition using an Agilent 7890A chromatography system. The ethylene conversion for 20h of reaction was defined as the initial activity and the ethylene conversion for reaction to 240h and the ethylene conversion change for 20h was defined as the stability of the catalyst.

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

The reactivity of the catalysts is shown in table 2, and the ethylation selectivity in the reaction product over all catalysts is greater than 99.7% during the reaction. The lowest ethylene conversion of 20h for Cat-B catalyst was only 90.00%, possibly with this sample containing a higher amount of Na ₂ O, resulting in a lower acid content of the catalyst. The ethylene conversion of the other catalysts for 20h did not change significantly,>99 percent, but when the reaction is carried out for 240 hours, the conversion rate of the ethylene on the catalyst containing the template agent Beta molecular sieve is respectively 90.14 percent and 92.62 percent when the catalyst containing the template agent Beta molecular sieve is treated by only ammonia water to obtain Cat-A and the catalyst not containing the template agent Beta molecular sieve is treated by ammonia water and IMD, and the conversion rate of the ethylene on the catalyst (Cat-D, cat-E, cat-F) prepared by the catalyst containing the template agent Beta molecular sieve through ammonia water and IMD is maintained to be more than 99 percent. We speculate that the ammonia water and the IMD treatment template-containing Beta molecular sieve catalyst have synergistic effect, but the synergistic effect of the template-free Beta molecular sieve catalyst is not obvious, and the RC of XRD of a sample can be proved, so that the stability of the catalyst is distinguished, and the specific reason needs to be further considered.

TABLE 1 composition of concentrated ethylene feed gas (% v)

Raw materials	H 2	N 2	CO x	CH 4	C 2 H 4	C 2 H 6	C 3 H 8	C 4 H 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

TABLE 2 evaluation results of catalytic reaction of catalysts

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (8)

1. A preparation method of a molecular sieve catalyst for high-concentration ethylene and benzene liquid-phase alkylation is as follows:

(1) Kneading Beta molecular sieve raw powder and a binder, molding and drying; wherein the weight content of the Beta molecular sieve raw powder is 65-85 percent, the weight content of the binder is 15-35 percent, and the binder is derived from one or two of aluminum oxide and silicon oxide;

(2) Placing the molded and dried sample in steam of mixed aqueous solution of ammonia water and Imidazole (IMD) for heat treatment, wherein the temperature is 60-150 ℃, and the time is 5-20 hours;

(3) And drying, roasting for the first time, acidifying and roasting for the second time on the treated sample to obtain the HBetaA molecular sieve catalyst.

2. The preparation method of the molecular sieve catalyst for the liquid-phase alkylation of high-concentration ethylene and benzene according to claim 1, wherein the weight ratio of the ammonia water in the step (2) to the dry basis of the molded and dried sample is 1.2-6.0%, and the weight of Imidazole (IMD) is 1.0-5.0% of the dry basis of the molded sample.

3. A process for the preparation of a catalyst for the liquid phase alkylation of ethylene with benzene in high concentration according to claim 1, wherein: the drying temperature in the step (3) is 120-150 ℃; the first roasting temperature is 450-600 ℃, and the roasting time is 5-10 h.

4. The process of claim 1 for the preparation of a molecular sieve catalyst for the liquid phase alkylation of ethylene with benzene at high concentration, wherein: the acidifying agent used in the step (3) is oxalic acid, and the concentration is as follows: 0.1-0.2N, the liquid-solid ratio is 4-6, the temperature is 60-80 ℃, and the acidification time is 1-2 h; the second roasting temperature is 400-500 ℃, and the roasting time is 1-2 h.

5. An HBetaA molecular sieve catalyst prepared by the process of any one of claims 1 to 4.

6. Use of a molecular sieve catalyst according to claim 5, wherein: the HBetaA catalyst is used for the liquid-phase alkylation reaction process of high-concentration ethylene and benzene.

7. Use according to claim 6, wherein the reaction conditions are: 180-260 ℃, 30-50 atm, ethylene weight space velocity: 0.1 to 0.8 hour ^-1 And the molar ratio of benzene to ethylene is 10-30.

8. Use according to claim 6, characterized in that: the high-concentration ethylene contains ethylene 60 to 99% v, hydrogen 0.1 to 0.5% v, nitrogen 0.1 to 0.5% v, and COx0.1 to 0.2% v, and methane 0.1 to 0.5% v, ethane 0.1 to 25% v, propane 0.1 to 20% v, and butane 0.1 to 20% v.