CN102344328B - Semi-continuous method for converting methyl alcohol into propylene by using moving bed technology - Google Patents

Abstract

The invention discloses a semi-continuous method for converting methanol into propylene by using moving bed technology, comprising: mixing a molecular sieve catalyst with a diluent and passing it into a first reaction zone; methanol raw material is passed into the first reaction zone to contact and react with the molecular sieve catalyst , to generate the first stream; the first stream is passed into the second reaction zone to contact and react with the molecular sieve catalyst to produce the second stream; the second stream is separated from the methanol raw material after heat exchange, dehydration and deoxidation, and the second stream is obtained. The return material of the second reaction zone, the output of the second reaction zone and the feed of the third reaction zone, the return material of the second reaction zone is merged into the first stream; the feed of the third reaction zone is passed into the third reaction zone and contacted with the molecular sieve catalyst to produce The third stream: the molecular sieve catalyst adopts a catalyst collector, which is periodically transported to the regeneration device for regeneration, and then intermittently merged into the molecular sieve catalyst for circulation. Only one molecular sieve catalyst is used to realize the three-stage reaction from methanol to propylene, thereby increasing the yield of propylene.

Description

A semi-continuous process for the conversion of methanol to propylene using moving bed technology

technical field

The invention relates to the field of preparing propylene by using the moving bed technology, in particular to a semi-continuous method for converting methanol into propylene by using the moving bed technology.

Background technique

Propylene is an important basic chemical raw material in the modern chemical industry, and is currently the second largest chemical in global demand. With the development of industrial economy in various countries in the world, the demand for propylene will increase. The traditional production route of propylene is the catalytic cracking of petroleum raw materials. Due to the limited amount of oil in the world and the rising international crude oil prices, the cost of producing propylene from oil is constantly increasing, which has triggered a research boom in the production of propylene technology (MTP) from relatively cheap methanol. Under the circumstances that the current crude oil price is very high and it is difficult to decrease in the future, for China, which is short of oil, gas, and rich in coal, the process technology of producing propylene from methanol has highlighted its strong competitiveness and far-reaching strategic significance.

At present, the relatively mature methanol-to-olefins processes in the world mainly include the methanol-to-olefins process (MTO) of UOP Company of the United States and the fixed-bed methanol-to-propylene process (MTP) of Lurgi Company of Germany. Domestically, there are the methanol-to-light olefins process (DMTO) developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the fluidized bed methanol-to-propylene process (FMTP) developed by Tsinghua University. The MTO process is mainly used to prepare ethylene and propylene, and the MTP process is mainly used to prepare propylene.

The fixed-bed methanol-to-propylene process was mainly developed by German Lurgi Company and formed a patented technology. European patent EP0448000B1 and Chinese patent CN1431982A have disclosed the process and the catalyst used. The process method is based on the modified ZSM-5 molecular sieve catalyst provided by Südchem, Germany, and adopts single-stage and multi-stage adiabatic fixed-bed reactors, which has a high yield of propylene and a small amount of by-products of ethylene, gasoline and liquefied petroleum gas ( LPG). Since the catalyst in the fixed bed needs to be regenerated intermittently in situ, usually a plurality of fixed bed reactors (such as two open and one standby, that is, two fixed bed reactors are used and one spare fixed bed reactor) is used to switch to solve the problem. However, this design method has the problems of high requirements for system equipment and complicated operation.

Fluidized bed technology was initially successfully researched and developed by UOP company. In addition, Dalian Institute of Chemical Physics and Tsinghua University are currently engaged in the development of this process in China. The fluidized bed technology mainly uses SAPO-34 catalyst, which has high selectivity to light olefins, but the single-pass selectivity to propylene is not high, and the wear of SAPO-34 catalyst in the fluidized bed is serious. Its industrial application needs to overcome the problems.

The moving bed technology has been paid more and more attention by researchers because of the small back-mixing of solids in the bed and the reaction close to plug flow, so the conversion rate of raw materials is high, and the catalyst in the bed is constantly moving (regenerated) so that it can maintain good catalytic performance. The Chinese patent application with the publication number CN1803738A discloses a moving-bed methanol-to-propylene technology. By using a dual-functional molecular sieve catalyst, the reaction-regeneration method is used to realize the cycle of the catalyst, and at the same time, the cycle conversion of by-products is introduced to improve the selection of propylene. sex. ZSM-5 is a molecular sieve catalyst with mesoporous nature and moderate carbon deposition rate. Moving bed technology is a continuous reaction regeneration technology, especially suitable for catalysts with medium carbon deposition rate. It can be continuously reacted and regenerated like a circulating fluidized bed, and at the same time it does not require a catalyst with high wear resistance.

The Chinese patent whose authorized announcement number is CN1152944C discloses a continuous reaction-regeneration device containing four reaction zones; the Chinese patent application whose publication number is CN 101367701A discloses a two-stage reaction zone, and the oxygen-containing compound raw material is used in the first stage The product is generated in the reaction zone, and then the components above C5 in the product are passed into the second reaction zone for catalyst pre-coking, and then the catalyst pre-coked in the second reaction zone is used for the reaction in the first reaction zone, and finally the catalyst is passed into Regenerator. This process of continuous reaction regeneration using a continuous reaction-regeneration device and the transfer of the catalyst from the second reaction zone to the first reaction zone require special air stripping between the reaction system and between the reaction system and the regeneration device. The device transports the catalyst flowing out of the reactor to the regeneration device for regeneration, which requires a lot of power for transmission, and has technical defects such as high energy consumption and poor economic benefits.

Contents of the invention

The invention provides a semi-continuous method for converting methanol into propylene by using the moving bed technology. Only one molecular sieve catalyst is used to realize the three-stage reaction from methanol to propylene in the moving bed, and finally achieve the purpose of increasing the yield of propylene.

A semi-continuous process for converting methanol to propylene using moving bed technology comprising the steps of:

1) The molecular sieve catalyst is mixed with the catalyst diluent and then continuously passed into the first reaction zone, and the methanol raw material is passed into the first reaction zone to contact with the molecular sieve catalyst. Stay in the first reaction zone for 30h to 100h to generate the first stream;

The first stream includes methanol, dimethyl ether and water;

The first reaction zone includes at least one moving bed reactor;

2) The molecular sieve catalyst after passing through the first reaction zone enters the second reaction zone, and the first stream obtained in step 1) is passed into the second reaction zone to contact with the molecular sieve catalyst. Under the condition of 0.8MPa, the molecular sieve catalyst stays in the second reaction zone for 30h to 100h to generate the second stream;

The second stream includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ;

The second reaction zone includes at least one moving bed reactor;

3) After the second stream produced in step 2) is exchanged heat with the methanol raw material in step 1), it is separated after dehydration and deoxidation (i.e., after gas-liquid separation and rectification, water and unconverted Oxidants such as methanol and dimethyl ether are separated), to obtain the second reaction zone return material, the second reaction zone output and the third reaction zone feed, and the second reaction zone return material is merged into the first stream and recycled to the step 2);

The return material of the second reaction zone includes ethylene, butene and C ₂ -C ₄ alkanes, the output of the second reaction zone includes C ₁ alkanes and propylene, and the feed of the third reaction zone includes C ₅ the above components;

4) The molecular sieve catalyst after passing through the second reaction zone enters the third reaction zone, and feeds the third reaction zone feed obtained in step 3) into the third reaction zone to contact with the molecular sieve catalyst. Under the condition of MPa～0.5MPa, the molecular sieve catalyst stays in the third reaction zone for 30h～100h to generate the third stream;

The third stream includes propylene, ethylene, butene, C ₁ -C ₄ alkanes and hydrocarbons above C ₅ ;

The third reaction zone includes at least one moving bed reactor;

The molecular sieve catalyst is mixed with the catalyst diluent and then transported continuously to the first reaction zone. The molecular sieve catalyst moves slowly and continuously, and flows through the first reaction zone, the second reaction zone, and the third reaction zone in sequence, and the molecular sieve catalyst is collected after passing through the third reaction zone. Afterwards, the regenerated catalyst is periodically regenerated to obtain the regenerated catalyst, which is intermittently incorporated into the molecular sieve catalyst and circulated to step 1).

In order to obtain better invention effects, the following are further preferred as the present invention:

The semi-continuous method for converting methanol into propylene using moving bed technology also includes: 5) separating the third stream obtained in step 4) from the feedstock in the second reaction zone after heat exchange, and separating to obtain ethylene , butene and C ₂ -C ₄ alkanes are incorporated into the first stream and recycled to step 2). The addition of step 5) further improves the energy utilization rate and material utilization rate in the conversion of methanol into propylene by using the moving bed technology in the present invention, and has better economic benefits.

The moving bed reactor can specifically select the existing moving bed reactor, such as a tubular moving bed reactor for the production of propylene using oxygenates as raw materials disclosed in the Chinese patent application number 201010175837.1, the application number is 200810120839.3 A radial moving bed reactor for the production of propylene with oxygenates as raw materials disclosed in the Chinese patent application, and a horizontal moving bed reactor for the production of propylene with oxygenates as raw materials disclosed in the Chinese patent application with application number 200810120838.9 moving bed reactor.

The catalysts in the three reaction zones are the same molecular sieve catalyst, the molecular sieve catalyst is preferably ZSM-5 molecular sieve, ZSM-5 molecular sieve is a molecular sieve catalyst with mesoporous properties, and has a medium carbon deposition rate, and Good wear resistance in moving bed. Since the reaction of methanol to propylene is a strong exothermic reaction, it is necessary to add inert solid particles with large specific heat capacity to dilute the catalyst to prevent local hot spots. The catalyst diluent is ceramic particles or quartz sand particles, and the catalyst diluent with larger specific heat capacity and the same particle size as the molecular sieve is generally selected. The mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:1-20. The methanol raw material can be different industrial raw materials, such as using methanol or a mixture of methanol and water, and the methanol raw material can contain a small amount of impurities.

Owing to adopting the dimethyl ether of the first stream in step 1) to generate propylene and other olefins, the heat of reaction is much lower than directly converting methanol into propylene, the present invention converts methanol into propylene and divides it into three steps, wherein the first step is mainly Convert methanol into dimethyl ether (first reaction zone), the second step is mainly to convert dimethyl ether into propylene (second reaction zone), and the third step is to crack high-carbon hydrocarbons into propylene (third reaction zone ). Thus, the reaction heat of converting methanol into propylene is divided into two parts, and the two parts of reaction heat are released in the first and second reaction zones respectively. Since the coke formation reaction is accelerated at a higher temperature, and at the same time, the dealumination reaction of the molecular sieve catalyst is accelerated, the present invention divides the reaction heat of converting methanol into propylene into two parts, thereby avoiding the excessive temperature rise in the process of converting methanol into propylene , not only can inhibit the formation of coke, but also can inhibit the dealumination of the catalyst, so that the catalyst can maintain high activity.

In the step 2), water vapor is added to the first stream and then passed into the second reaction zone to contact with the molecular sieve catalyst. The water vapor can be specifically selected from public works water vapor. The increase of water vapor can significantly reduce the carbon deposition of the molecular sieve catalyst, and keep the activity of the molecular sieve catalyst within a certain range for a long time. Preferably, the molar ratio of the first stream to steam is controlled at 0.25-4:1.

The reaction temperature of the second reaction zone is selected from 430°C to 530°C. In this temperature range, oxygen-containing compounds can be effectively converted into olefins. The lower temperature in this range is beneficial to the formation of propylene, while the higher temperature is beneficial to the formation of ethylene. In order to increase the conversion rate of propylene, the reaction temperature is preferably 450°C to 500°C.

The flow of the reaction raw material in the first reaction zone, the second reaction zone and the third reaction zone is countercurrent to the flow of the molecular sieve catalyst. Among them, the reaction raw material flow is introduced into the lower part of the reaction zone and removed from the upper part of the reaction zone, and the molecular sieve catalyst moves downward under the action of gravity, thus presenting a countercurrent. When the flow rate of the reaction feed stream is high, it occurs in the initial stage of the conversion, and the reaction feed stream is in contact with the partially deactivated molecular sieve catalyst, while when the flow rate of the reaction feed stream is low, it occurs in the subsequent deep stage of the conversion, and the reaction The raw material flow is in contact with the highly active molecular sieve catalyst, therefore, the flow of the methanol raw material and the molecular sieve catalyst in countercurrent can effectively maintain the selectivity of the catalyst to light olefins.

The residence time of the catalyst in the reaction zone (that is, the contact time of the reactants and the catalyst) has a significant impact on the conversion of methanol to propylene and the distribution of reaction products. If the residence time is short, the contact between the raw material and the catalyst is insufficient, and the reaction conversion rate is low. If the residence time is too long, it will easily lead to the increase of by-products such as methane, propane, butane and other alkanes and aromatics in the product. The contact time of reactant and catalyzer is represented by weight hourly space velocity (WHSV) usually, and WHSV refers to the ratio of the quality of reaction raw material in the feed per hour and the catalyst mass in the reactor, and the larger value of WHSV represents that the residence time is shorter, the present invention The WHSVs of the first reaction zone, the second reaction zone and the third reaction zone are all preferably 0.1 to 20 hr ^-1 .

The residence time of the molecular sieve catalyst in the reaction zone is preferably 90-300 hours. After the molecular sieve catalyst or the molecular sieve catalyst incorporated into the regenerated catalyst enters the moving bed reactor in the first reaction zone from the feed inlet, it moves slowly in the moving bed reactor, and then continuously moves through the moving bed reactor in the second reaction zone, The moving bed reactor in the third reaction zone moves out of the moving bed reactor after 90 to 300 hours and enters the catalyst collector.

In step 4), the molecular sieve catalyst (that is, the carbon-deposited molecular sieve catalyst) after passing through the third reaction zone adopts a catalyst collector, and the collected molecular sieve catalyst is regularly transported to the regeneration device for regeneration to obtain a regenerated catalyst, and the regenerated catalyst is incorporated into the molecular sieve catalyst Loop to step 1). The mass ratio of the regenerated catalyst to the molecular sieve catalyst before being incorporated into the regenerated catalyst (ie fresh molecular sieve catalyst) is 0-3:7. The reaction system is independent from the catalyst regeneration device, that is, after the catalyst accumulates to a certain amount, it is sent to the regeneration device for regeneration, which not only saves transportation costs, but also reduces the complexity of the device.

A device for converting methanol into propylene, comprising a catalyst feeding tank, a catalyst feeding controller, a first reaction zone, a second reaction zone, a third reaction zone, a catalyst discharge buffer tank, a catalyst discharge controller and Catalyst collector. Wherein, the first reaction zone, the second reaction zone and the third reaction zone respectively include at least one moving bed reactor. Each moving bed reactor is placed at different levels. Between adjacent moving bed reactors, the bottom of the moving bed reactor communicates with the top of the next moving bed reactor, for example, through pipelines or overlapping series of moving beds. Then, after each moving bed reactor is connected, the two ends are respectively connected with the catalyst feeding controller and the catalyst discharge buffer tank. The moving bed reactors connected in this way can ensure that the catalyst moves from top to bottom by its own gravity, and passes through each moving bed reactor sequentially from top to bottom. The raw material methanol and the catalyst form a cross flow, and energy consumption can be reduced.

The catalyst feeding controller is a valveless device for transferring catalyst from low pressure to high pressure. This valveless device controls the flow and cut-off of particles from low pressure to high pressure section through low pressure upper section, transition middle section, high pressure lower section, feeding pipe connecting adjacent two ends, blocking valve and attached throttling device.

The catalyst discharge controller is a valveless pressure locking device. When the pressure in the reactor is higher than the external atmospheric pressure, in order to transport the catalyst from the hopper to the reaction zone, it is necessary to increase the pressure of the catalyst inlet or reduce the pressure of the first reaction zone. A valveless pressure lock delivery device, the valveless pressure lock device can realize the delivery of catalyst particles from high pressure to low pressure without leaking the pressure in the moving bed reactor, realize a pressure lock function, and the pressure lock device can control the catalyst The feeding rate can greatly reduce the wear phenomenon of the catalyst during the feeding flow process.

The device for converting methanol into propylene also includes a regeneration device. The molecular sieve catalyst in the catalyst collector is sent to the regeneration device for regeneration by manual delivery, and then intermittently added to the catalyst feeding tank.

The first reaction zone, the second reaction zone and the third reaction zone are all equipped with heat exchange devices. The heat exchange device is located in the moving bed reactor and/or between the moving bed reactors. Installing a heat exchange device between the moving bed reactors can not only remove the reaction heat generated during the reaction process, but also facilitate better control of the reaction temperature of each step of the reaction, and the exchanged heat can preheat the materials at the entrances of each reaction zone , saving the heat input of public works, and achieving the purpose of comprehensively utilizing the heat energy of the system. When the exothermic heat is too large, the quenching device added between the moving bed reactors at this time, the specific heat exchanger of the quenching device can be selected, which can effectively remove unnecessary heat of reaction, as the second stream in step 3). After exchanging heat with the methanol raw material, the quenching liquid in the chilling device specifically uses methanol raw material, and the methanol raw material can be methanol or a mixture of methanol and water. When the methanol raw material is used, the processing capacity of the methanol raw material can be increased.

Compared with the prior art, the present invention has the following advantages:

1) The regenerated catalyst of the present invention is intermittently incorporated into the molecular sieve catalyst (i.e. fresh molecular sieve catalyst), continuously passes through the moving bed reaction zone, and the coke catalyst is collected in a centralized manner, and is regularly sent to the method for regeneration, using a molecular sieve catalyst to complete methanol The three-stage reaction of dimethyl ether production, dimethyl ether production of propylene, and cracking of high-carbon hydrocarbons realizes the continuous reaction between the material in the reactor and the molecular sieve catalyst, and the semi-continuous moving bed process of feeding and collecting the molecular sieve catalyst outside the reactor, which increases the reaction rate. The independence of the system and the regeneration device reduces the complexity of the whole set of equipment.

2) The present invention uses moving bed technology to convert methanol into propylene in a semi-continuous method. The reaction is divided into three sections for reaction. The three sections use the same molecular sieve catalyst, which can not only improve the conversion rate of methanol to dimethyl ether reaction section, but also reduce the final The content of methanol in the separated wastewater, and the reclamation of C ₂ ~ C ₄ low-carbon hydrocarbons and the cracking of high-carbon olefins above C 5 improve the selectivity of the final target product propylene, and at the same time avoid the need to draw out different catalysts in batches in operation Complexity of reproduction.

3) The present invention divides the reaction heat of methanol into propylene reaction process into two sections, and utilizes the reaction heat released by the etherification reaction in the first reaction zone to preheat the reaction raw materials entering the second reaction zone, so that the propylene synthesis reaction zone The average temperature rise can be effectively controlled, thereby reducing the carbon deposition and dealumination of the catalyst, and maintaining the high activity of the catalyst.

4) The present invention solves the impact of catalyst feed and discharge on the sealability of the reaction device by adding a catalyst feed controller and a catalyst discharge controller, and adopts the method of centralized collection of carbon-deposited catalysts and sending them to regeneration regularly, which simplifies the device design complexity.

5) In the present invention, a heat exchange device is added between the moving beds in each reaction zone, and the redundant reaction heat of the system is used to heat the inlet stream of the high-temperature section reaction zone, and the thermal energy of the reaction feed and the product discharge stream is comprehensively utilized .

6) The present invention adopts the overlapping arrangement of multiple reaction zones, and the continuous flow of the catalyst realizes the long-term continuous reaction. The present invention adopts the second reaction zone to remelt some products (ethylene, butene and C ₂ -C ₄ alkanes), thereby improving the selectivity of propylene. The present invention uses the third reaction zone to crack high-carbon hydrocarbons, and returns the separated refractory partial products (C ₂ to C ₄ alkanes, ethylene and butene) to the second reaction zone for reaction, reducing by-products content, improve the yield of propylene.

Description of drawings

Fig. 1 is a structural schematic diagram of the device for converting methanol into propylene according to the present invention.

Detailed ways

As shown in Figure 1, it is a device for converting methanol into propylene, including catalyst feeding tank ST1, catalyst feeding controller F1 (valveless device for catalyst transfer from low pressure to high pressure), first reaction zone D1, second Reaction zone D2, third reaction zone D3, catalyst discharge buffer tank B, catalyst discharge controller F2 and catalyst collector ST2 (valveless pressure lock device). The first reaction zone D1, the second reaction zone D2 and the third reaction zone D3 respectively comprise at least one moving bed reactor. Each moving bed reactor is placed at different levels. Between adjacent moving bed reactors, the bottom of the moving bed reactor communicates with the top of the next moving bed reactor, for example, through pipelines or overlapping series of moving beds. Next, each moving bed reactor is connected to the catalyst feed controller F1 and the catalyst discharge buffer tank B. The device for converting methanol into propylene also includes a regeneration device R, and the molecular sieve catalyst in the catalyst collector ST2 is sent to the regeneration device R periodically for regeneration by manual delivery, and then intermittently added to the catalyst feeding tank ST1. Heat exchange devices H1 , H2 , H3 , E1 and E2 are arranged in the first reaction zone D1 , the second reaction zone D2 and the third reaction zone D3 respectively. The heat exchange devices H1, H2 and H3 are located in the moving bed reactor and/or between the moving bed reactors, and are used for more accurate preheating of the materials at the inlets of each reaction zone. The heat exchanging devices E1 and E2 are used to preheat the materials at the inlets of each reaction zone by using the heat from the output of the reaction zone. The device for converting methanol into propylene of the present invention also includes separation zones sep1 and sep2.

The present invention uses moving bed technology to convert methanol into a semi-continuous method for propylene, comprising the following steps:

1) Molecular sieve catalyst and catalyst diluent are continuously added to the first reaction zone D1 from the top of the first reaction zone D1 through the catalyst feed tank ST1 through the catalyst feed controller F1, and the feed is controlled by adjusting the throttling device at the lower end of the feed controller F1 speed; the methanol raw material s passes through the heat exchange device H1 and then passes through the bottom of the first reaction zone D1 to the first reaction zone D1 to contact with the molecular sieve catalyst. The first reaction zone D1 stays for 30h to 100h, and the first stream a is generated at the outlet at the top of the first reaction zone D1;

The first stream a includes methanol, dimethyl ether and water;

The first reaction zone D1 includes at least one moving bed reactor;

2) The molecular sieve catalyst after passing through the first reaction zone D1 enters the second reaction zone D2 from the top of the second reaction zone D2, and the first stream a obtained in step 1) passes through the heat exchange device H2 and passes through the second reaction zone The bottom of D2 is passed into the second reaction zone D2 to contact with the molecular sieve catalyst. Under the conditions of 430°C-530°C and 0.1MPa-0.8MPa, the molecular sieve catalyst stays in the second reaction zone D2 for 30h-100h to generate the second stream c from the first The outlet at the top of the second reaction zone D2 flows out;

The second stream c includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ;

The second reaction zone D2 includes at least one moving bed reactor;

3) The second stream c in step 2) and the methanol raw material s in step 1) are exchanged in the heat exchange device E1, and then enter the separation zone sep1 after dehydration and deoxidation to separate, and obtain the return material d of the second reaction zone , the second reaction zone discharge p1 and the third reaction zone feed e, the second reaction zone return material d merges into the first stream a to form the second reaction zone feed b and circulates to step 2);

The second reaction zone return material d includes ethylene, butene and _C2 - _C4 alkanes, the second reaction zone output p1 includes _C1 alkanes and propylene, and the third reaction zone feed e Including components above _C5 ;

The second reaction zone discharge p1 is further separated to obtain C _alkane (fuel gas), propylene;

4) The molecular sieve catalyst after passing through the second reaction zone D2 enters the third reaction zone D3 from the top of the third reaction zone D3, and the third reaction zone feed e obtained in step 3) passes through the heat exchange device H3 from the third reaction zone The bottom of the reaction zone D3 leads into the third reaction zone D3 to contact with the molecular sieve catalyst. Under the conditions of 465°C-540°C and 0.1MPa-0.5MPa, the molecular sieve catalyst stays in the third reaction zone D3 for 30h-100h to generate the third stream f Flow out from the outlet at the top of the third reaction zone D3;

The third stream f includes propylene, ethylene, butene, C ₁ -C ₄ alkanes and C ₅ or more hydrocarbons;

The third reaction zone D3 includes at least one moving bed reactor;

5) The third stream f obtained in step 4) and the feedstock of the second reaction zone enter the separation zone sep2 after heat exchange in the heat exchange device E2 for separation, and the separated ethylene, butene and C ₂ ~ C ₄ alkanes are incorporated into The first stream a is recycled to step 2), and finally separated to obtain C ₁ alkane (fuel gas, containing a small amount of ethylene), propylene, C ₅ or more hydrocarbons (gasoline);

The molecular sieve catalyst is mixed with the catalyst diluent and then continuously transported to the first reaction zone D1. The molecular sieve catalyst moves slowly and continuously, and flows through the first reaction zone D1, the second reaction zone D2, the third reaction zone D3, and the third reaction zone D3. After the final molecular sieve catalyst passes through the molecular sieve catalyst discharge buffer tank B and the catalyst discharge controller F2, the feed rate of the molecular sieve catalyst is controlled by the catalyst discharge controller F2 under the buffer tank B (valveless pressure locking device). It is collected in the catalyst collector ST2, and is manually transported to the regeneration device R for regeneration to obtain the regenerated catalyst. The regenerated catalyst is intermittently incorporated into the molecular sieve catalyst and circulated to step 1), and the mass ratio of the regenerated catalyst to the molecular sieve catalyst before being incorporated into the regenerated catalyst (ie fresh molecular sieve catalyst) is 0-3:7.

For the separation method of separation zone sep1 and sep2, refer to the separation process method introduced in patent 200580025151.1 and patent 01810472.x.

In step 1), the molecular sieve catalyst is ZSM-5 molecular sieve. The catalyst diluent is ceramic or quartz sand particles. The mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:1-20.

In step 2), the first stream a is added with a material diluent and then passed into the second reaction zone D2 to contact with the molecular sieve catalyst. The material diluent is water vapor. The water vapor can be specifically selected from public works water vapor.

The flow of the reaction feedstock in the first reaction zone D1, the second reaction zone D2 and the third reaction zone D3 is countercurrent to the flow of the molecular sieve catalyst. The WHSVs of the first reaction zone D1, the second reaction zone D2 and the third reaction zone D3 are all 0.1˜20 hr ⁻¹ .

The structure of the device for converting methanol into propylene in Examples 1-3 can be as shown in FIG. 1 .

Example 1

1) The molecular sieve catalyst is mixed with the catalyst diluent and then continuously passed into the first reaction zone. The inlet temperature of the methanol raw material is 240°C. The methanol raw material is passed into the first reaction zone to contact with the molecular sieve catalyst. Under the condition of MPa～0.3MPa, the molecular sieve catalyst stays in the first reaction zone for 30h, and produces the first stream, and the outlet temperature of the first stream is 280°C;

The first reaction zone is a moving bed reactor;

2) The molecular sieve catalyst after passing through the first reaction zone enters the second reaction zone, and the first stream obtained in step 1) is added with utility water vapor and then passed into the second reaction zone to contact with the molecular sieve catalyst, the first stream The molar ratio of stream to water vapor is 1:1, the inlet temperature of the first stream is 450°C, and under the conditions of 450°C-500°C and 0.15MPa-0.2MPa, the molecular sieve catalyst stays in the second reaction zone for 30h, producing the first Two streams, the outlet temperature is 500°C;

The second stream includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ;

The second reaction zone is a moving bed reactor;

3) After the second stream in step 2) is heat-exchanged with the methanol raw material in step 1), after dehydration and deoxidation, water including a trace amount of oxygen-containing compounds is obtained, and then separated to obtain the second reaction zone return material, The output of the second reaction zone and the feed of the third reaction zone, the return material of the second reaction zone is merged into the first stream and recycled to step 2);

The return material of the second reaction zone includes ethylene, butene and C ₂ ~ C ₄ alkanes, the output of the second reaction zone includes C ₁ alkanes and propylene, and the feed of the third reaction zone includes C ₅ or more components;

The output of the second reaction zone is further separated to obtain C _alkane (fuel gas), propylene;

4) The molecular sieve catalyst after the second reaction zone enters the third reaction zone, and the third reaction zone feed obtained in step 3) is passed into the third reaction zone to contact the molecular sieve catalyst, and the inlet of the third reaction zone feed The temperature is 520°C, and under the conditions of 470°C-520°C and 0.1MPa-0.15MPa, the molecular sieve catalyst stays in the third reaction zone for 30 hours to generate a third stream, and the outlet temperature is 470°C;

The third stream includes propylene, ethylene, butene, C ₁ -C ₄ alkanes, and hydrocarbons above C ₅ ;

The third reaction zone is a moving bed reactor;

5) The third stream obtained in step 4) is separated after heat exchange with the feed material of the second reaction zone, and ethylene, butene and C ₂ ~ C ₄ alkanes are separated and incorporated into the first stream and recycled to step 2 ), finally separated to obtain a mixture (fuel gas) comprising C ₁ alkane and a small amount of ethylene, propylene, a small amount of C ₃ ~ C ₄ hydrocarbons (due to industrial production, all the C in the third stream could not be ₃ ~ C ₄ alkanes, propylene and butene are all separated, and in the final discharge, there are still a small amount of C ₃ ~ C ₄ hydrocarbons, as liquefied petroleum gas), and hydrocarbons above C ₅ (gasoline).

The molecular sieve catalyst is ZSM-5 molecular sieve with a particle diameter of 1.5-2 mm. The catalyst diluent is ceramic particles with approximately the same size as the molecular sieve catalyst, and the mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:3.

The residence time of the molecular sieve catalyst (carbon deposition catalyst) removed from the bottom of the bed of the moving bed reactor in the third reaction zone is 90 hours in the bed, and the amount of carbon deposition is less than 3%. It is collected in the catalyst collector and concentrated regularly Sent to the regenerator for regeneration to obtain a regenerated catalyst, the amount of carbon deposited on the regenerated catalyst is less than 0.5% (the amount of carbon deposited = the mass of deposited carbon deposited on the catalyst per unit weight). The regenerated catalyst is intermittently incorporated into the molecular sieve catalyst and circulated to step 1), and the mass ratio of the regenerated catalyst to the fresh molecular sieve catalyst is 1:7.

The WHSVs of the first reaction zone, the second reaction zone and the third reaction zone are respectively 10hr ^-1 , 15hr ^-1 , and 20hr ^-1 .

Table 1 lists the material balance under the above conditions, which is obtained based on the experimental data through computer simulation and scaling up to the annual processing capacity of one million tons of methanol. It can be seen from Table 1 that the amount of methanol feed is 207383kg/h, the amount of propylene produced is 66275kg/h, and the conversion rate of methanol is greater than 98%.

Table 1 Material Balance

material Material flow Methanol 207383kg/h Propylene 62275kg/h Liquefied Petroleum Gas (LPG) 4032kg/h gasoline 17905kg/h Water (including trace oxygenates) 118076kg/h Fuel Gas# 1466kg/h Coke* 82kg/h

In Table 1, # indicates that a small amount of ethylene is included, and * indicates that it includes the loss in material circulation; where LPG is C ₃ to C ₄ hydrocarbons, mainly alkanes, including a small amount of olefins; gasoline is hydrocarbons above C ₅ , containing a small amount of C ₄ hydrocarbons, mainly heavy components above C7; water is the product of methanol dehydration, including traces of unreacted methanol and generated dimethyl ether, aldehydes and other trace oxygenates; fuel gas is mainly a small amount of C ₁ ~ C ₂ hydrocarbons Class components (mainly C ₁ alkanes, containing a small amount of ethylene), coke is the carbon deposition on the catalyst, the same below.

Each product was converted into the dry basis percentage content except water, and the product distribution relative to the raw material methanol was listed, as shown in Table 2.

Table 2 Product distribution

product Percentage of dry basis Propylene 72.62% Liquefied Petroleum Gas (LPG) 4.70% gasoline 20.88% fuel gas 1.71% Coke 0.10%

Example 2

1) The molecular sieve catalyst is mixed with the catalyst diluent and then continuously passed into the first reaction zone. The inlet temperature of the methanol raw material is 260°C. The methanol raw material is passed into the first reaction zone to contact with the molecular sieve catalyst. Under the condition of MPa ~ 0.6MPa, the molecular sieve catalyst stays in the first reaction zone for 50 hours to generate the first stream, and the outlet temperature of the first stream is 300°C;

The first reaction zone is a moving bed reactor;

2) The molecular sieve catalyst after passing through the first reaction zone enters the second reaction zone, and the first stream obtained in step 1) is added with utility water vapor and then passed into the second reaction zone to contact with the molecular sieve catalyst, the first stream The molar ratio of stream to water vapor is 4:1, the inlet temperature of the first stream is 470°C, and under the conditions of 470°C-520°C and 0.2MPa-0.4MPa, the molecular sieve catalyst stays in the second reaction zone for 50h, producing the first Two streams, the outlet temperature is 520°C;

The second stream includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ;

The second reaction zone is a moving bed reactor;

3) After the second stream in step 2) is heat-exchanged with the methanol raw material in step 1), after dehydration and deoxidation, water including a trace amount of oxygen-containing compounds is obtained, and then separated to obtain the second reaction zone return material, The output of the second reaction zone and the feed of the third reaction zone, the return material of the second reaction zone is merged into the first stream and recycled to step 2);

The return material of the second reaction zone includes ethylene, butene and C ₂ ~ C ₄ alkanes, the output of the second reaction zone includes C ₁ alkanes and propylene, and the feed of the third reaction zone includes C ₅ or more components;

The second reaction zone discharge is further separated to obtain mixture (fuel gas) and propylene comprising C _alkane and a small amount of ethylene;

4) The molecular sieve catalyst after the second reaction zone enters the third reaction zone, and the third reaction zone feed obtained in step 3) is passed into the third reaction zone to contact the molecular sieve catalyst, and the inlet of the third reaction zone feed The temperature is 530°C. Under the conditions of 480°C-530°C and 0.1MPa-0.2MPa, the molecular sieve catalyst stays in the third reaction zone for 50 hours to generate a third stream, and the outlet temperature is 480°C;

The third stream includes propylene, ethylene, butene, C ₁ -C ₄ alkanes, and hydrocarbons above C ₅ ;

The third reaction zone is a moving bed reactor;

5) The third stream obtained in step 4) is separated after heat exchange with the feed material of the second reaction zone, and ethylene, butene and C ₂ ~ C ₄ alkanes are separated and incorporated into the first stream and recycled to step 2 ), finally separated to obtain a mixture (fuel gas) comprising C ₁ alkane and a small amount of ethylene, propylene, a small amount of C ₃ ~ C ₄ hydrocarbons (due to industrial production, all the C in the third stream could not be ₃ -C ₄ alkanes, propylene and butene are all separated, and a small amount of C ₃ -C ₄ hydrocarbons are still included in the final discharge, as liquefied petroleum gas), and hydrocarbons above C ₅ (gasoline).

The molecular sieve catalyst is ZSM-5 molecular sieve with a particle diameter of 1.5-2mm. The catalyst diluent is quartz sand particles with approximately the same size as the molecular sieve catalyst, and the mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:5.

The residence time of the molecular sieve catalyst (carbon deposition catalyst) removed from the bottom of the bed of the moving bed reactor in the third reaction zone is 150 hours in the bed, and the amount of carbon deposition is less than 3%, which is collected in the catalyst collector and concentrated regularly Sent to the regenerator for regeneration to obtain a regenerated catalyst, the amount of carbon deposited on the regenerated catalyst is less than 0.5% (the amount of carbon deposited = the mass of deposited carbon deposited on the catalyst per unit weight). The regenerated catalyst is intermittently incorporated into the molecular sieve catalyst and circulated to step 1), and the mass ratio of the regenerated catalyst to the fresh molecular sieve catalyst is 3:7.

The WHSVs of the first reaction zone, the second reaction zone and the third reaction zone are respectively 12hr ^-1 , 15hr ^-1 , and 18hr ^-1 .

Table 3 lists the material balance under the above conditions. The material balance is obtained based on the experimental data and scaled up to the annual processing capacity of one million tons of methanol through computer simulation. It can be known from Table 3 that the amount of methanol feed is 207383kg/h, the amount of propylene produced is 64451kg/h, and the conversion rate of methanol is greater than 99%.

Table 3 Material Balance

material Material flow Methanol 207383kg/h Propylene 64451kg/h Liquefied Petroleum Gas (LPG) 4309kg/h gasoline 17768kg/h Water (including trace oxygenates) 118736kg/h

Fuel Gas# 1588kg/h Coke* 83kg/h

In Table 3, # means to include a small amount of ethylene, and * means to include losses in material circulation;

Each product was converted into a percentage content on a dry basis except water, and the product distribution relative to the raw material methanol was listed, as shown in Table 4.

Table 4 product distribution

product Percentage of dry basis Propylene 73.07% Liquefied Petroleum Gas (LPG) 4.89% gasoline 20.15% fuel gas 1.80% coke 0.09%

Example 3

1) The molecular sieve catalyst is mixed with the catalyst diluent and then continuously passed into the first reaction zone. The inlet temperature of the methanol raw material is 280°C. The methanol raw material is passed into the first reaction zone to contact with the molecular sieve catalyst. Under the condition of MPa～1MPa, the molecular sieve catalyst stays in the first reaction zone for 100h to generate the first stream, and the outlet temperature of the first stream is 320°C;

The first reaction zone is a moving bed reactor;

2) The molecular sieve catalyst after passing through the first reaction zone enters the second reaction zone, and the first stream obtained in step 1) is added with utility water vapor and then passed into the second reaction zone to contact with the molecular sieve catalyst, the first stream The molar ratio of stream to water vapor is 1:4, the inlet temperature of the first stream is 480°C, and under the conditions of 480°C-530°C and 0.3MPa-0.5MPa, the molecular sieve catalyst stays in the second reaction zone for 100h, producing the first Two streams, the outlet temperature is 530°C;

The second stream includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ;

The second reaction zone is a moving bed reactor;

3) After the second stream in step 2) is heat-exchanged with the methanol raw material in step 1), after dehydration and deoxidation, water including a trace amount of oxygen-containing compounds is obtained, and then separated to obtain the second reaction zone return material, The output of the second reaction zone and the feed of the third reaction zone, the return material of the second reaction zone is merged into the first stream and recycled to step 2);

The return material of the second reaction zone includes ethylene, butene and C ₂ ~ C ₄ alkanes, the output of the second reaction zone includes C ₁ alkanes and propylene, and the feed of the third reaction zone includes C ₅ or more components;

The second reaction zone discharge is further separated to obtain mixture (fuel gas) and propylene comprising C _alkane and a small amount of ethylene;

4) The molecular sieve catalyst after the second reaction zone enters the third reaction zone, and the third reaction zone feed obtained in step 3) is passed into the third reaction zone to contact the molecular sieve catalyst, and the inlet of the third reaction zone feed The temperature is 540°C. Under the conditions of 490°C-540°C and 0.1MPa-0.3MPa, the molecular sieve catalyst stays in the third reaction zone for 100h to generate a third stream, and the outlet temperature is 490°C;

The third stream includes propylene, ethylene, butene, C ₁ -C ₄ alkanes, and hydrocarbons above C ₅ ;

The third reaction zone is a moving bed reactor;

5) The third stream obtained in step 4) is separated after heat exchange with the feed material of the second reaction zone, and ethylene, butene and C ₂ ~ C ₄ alkanes are separated and incorporated into the first stream and recycled to step 2 ), finally separated to obtain a mixture (fuel gas) comprising C ₁ alkane and a small amount of ethylene, propylene, a small amount of C ₃ ~ C ₄ hydrocarbons (due to industrial production, all the C in the third stream could not be ₃ -C ₄ alkanes, propylene and butene are all separated, and a small amount of C ₃ -C ₄ hydrocarbons are still included in the final discharge, as liquefied petroleum gas), and hydrocarbons above C ₅ (gasoline).

The molecular sieve catalyst is ZSM-5 molecular sieve with a particle diameter of 1.5-2 mm. The catalyst diluent is ceramic particles with approximately the same size as the molecular sieve catalyst, and the mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:8.

The residence time of the molecular sieve catalyst (carbon deposition catalyst) removed from the bottom of the bed of the moving bed reactor in the third reaction zone is 300 hours in the bed, and the amount of carbon deposition is less than 3%, which is collected in the catalyst collector and concentrated regularly Sent to the regenerator for regeneration to obtain a regenerated catalyst, the amount of carbon deposited on the regenerated catalyst is less than 0.5% (the amount of carbon deposited = the mass of deposited carbon deposited on the catalyst per unit weight). The regenerated catalyst is intermittently incorporated into the molecular sieve catalyst and circulated to step 1), and the mass ratio of the regenerated catalyst to the fresh molecular sieve catalyst is 2:7.

The WHSVs of the first reaction zone, the second reaction zone and the third reaction zone are respectively 8hr ^-1 , 12hr ^-1 , and 16hr ^-1 .

Table 5 lists the material balance under the above conditions. The material balance is obtained based on the experimental data and scaled up to the annual processing capacity of one million tons of methanol through computer simulation. It can be known from Table 5 that the feed amount of methanol is 207383kg/h, the amount of propylene produced is 69380kg/h, and the conversion rate of methanol is 100%.

Table 5 Material Balance

material Material flow

Methanol 207383kg/h Propylene 69380kg/h Liquefied Petroleum Gas (LPG) 5703kg/h gasoline 15656kg/h Water (including trace oxygenates) 115063kg/h Fuel Gas# 1487kg/h Coke* 94kg/h

In Table 5, # means to include a small amount of ethylene, and * means to include losses in material circulation;

Each product was converted into a percentage content on a dry basis except water, and the product distribution relative to the raw material methanol was listed, as shown in Table 6.

Table 6 product distribution

product Percentage of dry basis Propylene 75.15% Liquefied Petroleum Gas (LPG) 6.18% gasoline 16.96% fuel gas 1.61% coke 0.10%

It can be seen from the above three examples that according to the process disclosed in the present invention, better temperature control, catalyst online reaction time and higher propylene selectivity can be obtained. In addition, operating within the scope disclosed in the present invention, the range of selectivity of the product is small.

Claims (3)

1. A semi-continuous method using moving bed technology to convert methanol into propylene, comprising the following steps: 1) The molecular sieve catalyst is mixed with the catalyst diluent and then continuously passed into the first reaction zone, and the methanol raw material is passed into the first reaction zone to contact with the molecular sieve catalyst. Stay in the first reaction zone for 30h to 100h to generate the first stream; The first stream includes methanol, dimethyl ether and water; The first reaction zone includes at least one moving bed reactor; Described molecular sieve catalyst is ZSM-5 molecular sieve; The catalyst diluent is ceramic particles or quartz sand particles; The mass ratio of the molecular sieve catalyst to the catalyst diluent is 1:1-20; 2) The molecular sieve catalyst after passing through the first reaction zone enters the second reaction zone, and the first stream obtained in step 1) is passed into the second reaction zone to contact with the molecular sieve catalyst. Under the condition of 0.8MPa, the molecular sieve catalyst stays in the second reaction zone for 30h to 100h to generate the second stream; The second stream includes ethylene, propylene, butene, C ₁ -C ₄ alkanes and components above C ₅ ; The second reaction zone includes at least one moving bed reactor; After adding a material diluent to the first stream, it is passed into the second reaction zone to contact with the molecular sieve catalyst; The material diluent is water vapor; 3) The second stream produced in step 2) is exchanged with the methanol raw material in step 1), and separated after dehydration and deoxidation to obtain the return material of the second reaction zone, the output material of the second reaction zone and the second Three reaction zone feeding, the second reaction zone return material is merged into the first stream and recycled to step 2); The return material of the second reaction zone includes ethylene, butene and C ₂ -C ₄ alkanes, the output of the second reaction zone includes C ₁ alkanes and propylene, and the feed of the third reaction zone includes C ₅ The above components; 4) The molecular sieve catalyst after passing through the second reaction zone enters the third reaction zone, and the third reaction zone feed obtained in step 3) is passed into the third reaction zone to contact with the molecular sieve catalyst. Under the conditions of 540°C and 0.1MPa~0.5MPa, the molecular sieve catalyst stays in the third reaction zone for 30h~100h to generate the third stream; The third stream includes propylene, ethylene, butene, C ₁ -C ₄ alkanes and hydrocarbons above C ₅ ; The third reaction zone includes at least one moving bed reactor; The molecular sieve catalyst is mixed with the catalyst diluent and then transported continuously to the first reaction zone. The molecular sieve catalyst moves slowly and continuously, and flows through the first reaction zone, the second reaction zone, and the third reaction zone in sequence, and the molecular sieve catalyst is collected after passing through the third reaction zone. Afterwards, the regenerated catalyst is periodically regenerated, and the regenerated catalyst is intermittently incorporated into the molecular sieve catalyst and circulated to step 1); 5) The third stream obtained in step 4) is separated after heat exchange with the feed material of the second reaction zone, and the separated ethylene, butene and C ₂ ~ C ₄ alkanes are incorporated into the first stream and recycled to step 2 ); The flow of the reaction raw material in the first reaction zone, the second reaction zone and the third reaction zone is countercurrent to the flow of the molecular sieve catalyst. 2. The semi-continuous method for converting methanol into propylene using moving bed technology according to claim 1, wherein the mass ratio of the regenerated catalyst to the molecular sieve catalyst before being incorporated into the regenerated catalyst is 0 to 3: 7. 3. the semi-continuous method that methanol is converted into propylene by using moving bed technology according to claim 1, is characterized in that, the WHSV of described first reaction zone, second reaction zone and the 3rd reaction zone are all 0.1～ 20hr ^-1 .