CN-116870803-B - Method for prolonging single-pass service life of MMA catalyst

Abstract

The invention provides a method for prolonging the single-pass service life of an MMA catalyst, which slightly changes the airspeed every a small period of time in the process of maintaining stable airspeed for a long time, changes the conversion rate of raw materials, thereby changing the atmosphere proportion in a catalyst layer bed, generating gas turbulence disturbance, driving the materials in the fine pore diameter of the catalyst to quickly wash and exchange, thereby reducing carbon deposition and prolonging the single-pass service life of the catalyst.

Inventors

• YANG DONGMEI
• ZHOU SHUAILIN
• QIN SHAOPENG
• DENG XIAONAN
• ZHANG LINGXIA
• WANG YAOHONG
• CHEN XIBO

Assignees

• 北京旭阳科技有限公司

Dates

Publication Date

20260505

Application Date

20230629

Claims (6)

1. 1. A method of extending the single pass service life of an MMA catalyst comprising the steps of: In the process of preparing methyl methacrylate by using an MMA catalyst to catalyze formaldehyde and methyl propionate to react, setting liquid hourly mass space velocity SV 0 of initial feeding in a fixed bed reactor, regulating the liquid hourly mass space velocity to SV 1 after reaction time H 1 , regulating the liquid hourly mass space velocity back to SV 0 +/-d after reaction time H 1 , regulating the liquid hourly mass space velocity to SV 2 after reaction time H 2 , regulating the liquid hourly mass space velocity back to SV 0 +/-d after reaction time H 2 , continuously repeating the above processes, namely regulating the liquid hourly mass space velocity to SV n after reaction time H n , regulating the liquid hourly mass space velocity back to SV 0 +/-d after reaction time H n , wherein d is the value of 0-1% SV 0 , n is an integer larger than 2, H 1 is 20-100 hours, H 2 、H n is independently 20-800 hours, H 1 is 0.08-0.15 hours, H 2 、h n is independently 0.08-0.5 hours, Wherein, the SV 0 is 0.5-10.5h -1 , SV 1 、SV 2 、SV n are each independently SV 0 ±d, where D is each 5% -20% SV 0 value.
2. 2. The method of claim 1, wherein, The MMA catalyst is a supported catalyst and comprises a carrier, an active component and an active auxiliary agent, wherein the carrier is one or more selected from SiO 2 、TiO 2 and Al 2 O 3 , the active component is oxide of Cs, and the active auxiliary agent is at least one oxide selected from Na, K, mg, ca, zr, cu, fe, au, ce.
3. 3. The method according to claim 1 or 2, wherein, The methyl methacrylate is prepared by catalyzing formaldehyde and methyl propionate to react by using an MMA catalyst, the methyl propionate and formaldehyde source serving as raw materials are dissolved in methanol and are sent into a fixed bed reactor containing the MMA catalyst to react by a micro metering pump.
4. 4. The method of claim 3, wherein, The formaldehyde source is one selected from formaldehyde, paraformaldehyde, trioxymethylene and methylal.
5. 5. The method of claim 3, wherein, The molar ratio of methyl propionate to formaldehyde source is 1:5 to 10:1, and the molar ratio of methanol to formaldehyde source is 0.5:1 to 10:1.
6. 6. The method of claim 3, wherein, The reaction temperature is 300-450 ℃ and the pressure is 0.1-1.0MPa.

Description

Method for prolonging single-pass service life of MMA catalyst Technical Field The invention relates to the technical field of catalyst use, in particular to a method for prolonging the single-pass service life of an MMA catalyst. Background Methyl methacrylate (abbreviated as MMA, english name METHYL METHACRYLATE) is an important organic chemical raw material, is mainly used for producing organic glass (polymethyl methacrylate, PMMA), and is also used for producing other resins, plastics, paint, adhesives, lubricants, impregnating compounds for wood and cork, impregnating compounds for motor coils, paper polishing agents, printing and dyeing auxiliary agents, insulating pouring materials and the like, and the application is quite wide. The traditional MMA synthesis method mainly comprises an acetone cyanohydrin method (ACH method), an isobutene method and an ethylene method, and an Alpha method appears later, wherein the main raw materials of the MMA synthesis method are ethylene, CO, methanol, formaldehyde, water and the like, and can be produced by coal chemical industry, and China has rich coal resources, so that the situation of insufficient production of low-carbon olefin can be obviously solved along with the production of devices such as coal-to-olefin and the like in the market. Compared with the existing acetone cyanohydrin method or isobutene method, the Alpha method for producing MMA by using the coal chemical raw material can reduce the production cost of MMA by 40%. The method has the advantages of environment friendliness, safety, mild reaction, low corrosion of the device, low production cost and the like, enriches the technology of manufacturing large chemical products by non-petroleum routes, and has great significance. The Alpha process mainly comprises the steps of reacting ethylene, methanol and CO to generate methyl propionate, and reacting methyl propionate with formaldehyde to generate MMA and water, wherein a special heterogeneous catalyst is adopted, the Alpha process has multi-variable multi-factor mutual influence, and the variable adjustment is complex. The biggest problem at present is the reduction of catalyst activity caused by carbon deposition, and the single-pass service life is short. Disclosure of Invention The invention aims to provide a method for prolonging the single-pass service life of an MMA catalyst. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: The invention provides a method for prolonging the single-pass service life of an MMA catalyst (particularly a catalyst for preparing methyl methacrylate by reacting formaldehyde and methyl propionate), which comprises the following steps: In the preparation of methyl methacrylate by using a MMA catalyst to catalyze the reaction of formaldehyde and methyl propionate, the liquid hourly mass space velocity SV 0 of the initial feed is set, the liquid hourly mass space velocity is regulated to SV 1 after the reaction time H 1, the liquid hourly mass space velocity is regulated back to SV 0 + -d after the reaction time H 1, the liquid hourly mass space velocity is regulated to SV 2 after the reaction time H 2, the liquid hourly mass space velocity is regulated back to SV 0 + -d after the reaction time H 2, the liquid hourly mass space velocity is regulated to SV n after the reaction time H n, the liquid hourly mass space velocity is regulated back to SV 0 + -d after the reaction time H n, wherein d is the value of 0-1% SV 0 (such as 0.5% SV 0), and n is an integer (such as 3,4, 5, 6, 7, 8, 9, 10), preferably 3,4, 5 and the like. The single-pass service life of the MMA catalyst refers to the time that the catalyst can be used once per activation, the testing method can stop when the mass percentage of MMA in the product liquid is reduced to 90% of the initial value, and the time is recorded as the single-pass service life of the MMA catalyst. Liquid hourly space velocity refers to the mass of MMA catalyst per unit mass per hour of liquid reactant treated, i.e., the total feed mass per unit mass of MMA catalyst per hour of total liquid material such as methyl propionate, formaldehyde source, and methanol. According to one embodiment of the present disclosure, SV 0 is 0.01-20h -1, preferably 0.5-10.5h -1, e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 12, 15, 16, 18h -1. According to one embodiment of the present disclosure, SV 1、SV2……SVn is each independently SV 0 ±d, where D is each a value of 5% -20% SV 0, e.g., a value of 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, 16%, 18%, 20% SV 0. According to one embodiment of the present disclosure, each H 1、H2……Hn is independently 20-800 hours, e.g., 24, 36, 48, 60, 72, 84, 100, 200, 300, 400, 500, 600, 700H, 800H. According to one embodiment of the present disclosure, h 1、h2……hn is each independently 0.08-0.5 hours, e.g., 0.1, 0.15, 0.2, 0.25, 0.3, 0.5 hours. Under the fluctuation condition that th