WO2008025247A1

WO2008025247A1 - A process for recovering regenerated heat during the production of lower olefins from methanol

Info

Publication number: WO2008025247A1
Application number: PCT/CN2007/002537
Authority: WO
Inventors: Zhongmin Liu; Yue Qi; Zhihui Lv; Changqing He; Lei Xu; Jinling Zhang; Xiangao Wang
Original assignee: Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences
Priority date: 2006-08-23
Filing date: 2007-08-22
Publication date: 2008-03-06
Also published as: CN101130469A; JP2010501495A; BRPI0715687A2; CN101130469B; ZA200901045B; AU2007291786A1; KR20090057027A

Abstract

Disclosed is a process for recovering regenerated heat during the production of lower olefins from methanol by using fluidized bed. The process is characterized in that, before contacting with methanol, the regenerated catalysts at high temperature enter a heat absorbing cracking reaction area in which said catalysts contact with hydrocarbons. The cracking reaction of said hydrocarbons absorbs a part of heat carried by the regenerated catalysts in order to reduce the temperature of said catalysts to satisfy the temperature requirement of the methanol conversion.

Description

Method for recovering heat of regeneration in process of preparing low carbon olefin from methanol

Technical field

The present invention relates to a method for recovering heat of regeneration, and more particularly to a method for recovering heat carried by a high-temperature catalyst after regeneration of a methanol to produce a low-carbon olefin. Background technique

Low-carbon olefins such as ethylene and propylene are the basic raw materials for the chemical industry. Traditionally, the sources of ethylene and propylene have been mainly steam cracking of hydrocarbons. The raw materials used are naphtha, light diesel oil and hydrocracked tail oil. In recent years, as the price of petroleum has risen sharply, the production cost of using the above raw materials to obtain ethylene and propylene has been rising. At the same time, the traditional method for the production of ethylene and propylene mainly uses high-temperature tube furnace cracking process, and the energy consumption is relatively high. These factors have prompted the development of new processes for the production of olefins.

The use of non-petroleum feedstocks to produce low-carbon olefins has been a process of much concern in recent years. Among them, the process of converting coal or natural gas into methanol by syngas and then converting it into low-carbon olefin by methanol has received extensive attention. The process of selectively producing low carbon (c ₂ -c ₄ ) olefins on a molecular sieve catalyst by methanol (or dehydration from methanol to dimethyl ether) is commonly referred to as the MT0 process.

In recent years, the continuous reaction-regeneration fluidized bed MT0 process has received much attention. The basic principle of the fluidized bed process is that the raw material methanol and the catalyst are mixed in a reactor to be fluidized, and converted to a mixture containing products such as ethylene and propylene at a certain temperature, and the catalyst is partially or completely produced by carbonation after the reaction. Inactivated. The gaseous reaction product flows from the reactor into the separation unit, and the deactivated catalyst continuously flows out of the reactor into the regenerator for regeneration, i.e., combustion in an oxygen-containing atmosphere to remove carbon deposits, and then returned to the reactor for contact with the reaction feed.

In the above continuous reaction-regenerated fluidized bed process, the surface area carbon of the deactivated catalyst is removed by high temperature combustion. Generally, the combustion reaction temperature is higher than 600 Ό and up to 700 ° C or higher. Excluding the loss of heat dissipation, the heat generated by the combustion of carbon deposits is transferred out of the regenerator in two ways: The discharged high temperature regenerated flue gas carries away some of the heat, while the other part of the heat is carried away by the regenerated high temperature catalyst.

On the one hand, the heat from the high-temperature regenerated flue gas is usually recovered by means of steam production or power generation. For example, US Patent No. 2,050,238, 543 A1 discloses a method for recovering heat from regenerated flue gas, including regenerating flue gas. The heat is cooled by multiple heat exchanges, and the heat taken out is used to generate steam or the like.

On the other hand, the heat from the regenerated high-temperature catalyst is often used for reaction heating. Traditionally, fluidized The bed reaction process is generally applied to an endothermic reaction such as catalytic cracking of a hydrocarbon, and a part of the heat of reaction is provided by regenerating a high-temperature catalyst which is regenerated after being regenerated. That is, the deactivated catalyst is combusted in an oxygen-containing atmosphere in the regenerator to remove carbon deposits, regenerated and heated, and then returned to the reactor while transferring heat from the former to the latter to provide at least a portion of the heat of reaction.

However, this way of utilizing heat is not suitable for the conversion of methanol to olefins. Since the conversion of methanol to olefins is a strongly exothermic reaction, the catalyst is heated in the reactor, and only the temperature of the catalyst entering the reactor is lower than the temperature of the reaction bed to maintain the stability of the reaction temperature. The optimum reaction temperature for the conversion of methanol to lower olefins is 350-600 Torr, which is lower than the regeneration temperature of the catalyst charcoal (600-700 ° C), ie the catalyst temperature after regeneration. Therefore, the regenerated high-temperature catalyst must release the heat obtained during the regeneration process, and then enter the reactor after cooling to meet the needs of methanol conversion to low-carbon olefins. Summary of the invention

SUMMARY OF THE INVENTION One object of the present invention is to provide a method for recovering heat of a high temperature catalyst after regeneration in the process of preparing a low carbon olefin from methanol.

The present inventors have completed the present invention through intensive research.

In one aspect of the invention, there is provided a method for recovering heat from a regenerated high temperature catalyst in the process of preparing a low carbon olefin from methanol, the method comprising the steps of: first entering a regenerated high temperature catalyst into a cracking reaction endothermic zone And then enter the methanol conversion reactor, where

Introducing a hydrocarbon into the endothermic zone of the cracking reaction and contacting it with the regenerated high temperature catalyst to cause a cracking reaction;

The temperature of the regenerated high temperature catalyst is from 500 to 800 °C.

O. 6nm。 The catalyst having a microporous pore size of 0. 3- 0. 6nm.

In another preferred aspect of the invention, the matrix material of the catalyst is one or more of silica, alumina or clay.

In a preferred aspect of the invention, the temperature of the endothermic zone of the cracking reaction is from 400 to 700 °C.

In another preferred aspect of the invention, the temperature difference between the inlet and the outlet of the catalyst in the endothermic zone of the cracking reaction is from 50 to 300 Torr.

In a preferred aspect of the present invention, a hydrocarbon cracking reaction zone forming the olefin introduced into the endothermic reaction of the above C ₄ product is methanol, and / or other C ₄ -C _2. Hydrocarbons. In another preferred aspect of the invention, the hydrocarbons introduced in the endothermic zone of the cracking reaction are naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or/and kerosene.

In a preferred aspect of the invention, the product produced by the hydrocarbon in the endothermic zone of the cracking reaction is combined into the product obtained from the methanol to the lower olefin.

In another preferred aspect of the invention, the endothermic zone of the cracking reaction is a separate reaction zone in the methanol conversion zone.

In a preferred aspect of the invention, the cleavage reaction endothermic zone is a literate section of a methanol conversion reactor. By adopting the method of the present invention, part of the heat carried by the catalyst after regeneration in the process of methanol-made low-carbon olefin can be recovered, and the temperature of the catalyst after regeneration can be adjusted to meet the temperature requirement of methanol conversion to olefin reaction. detailed description

In order to achieve the above object, the method for recovering heat of regeneration in the process of preparing low-carbon olefin from methanol is provided by flowing the regenerated high-temperature catalyst into a cracking reaction endothermic zone, and the hydrocarbon catalytic cracking reaction is carried out in the endothermic zone. The heat carried by the catalyst is absorbed, and the temperature of the catalyst is lowered to enter the methanol conversion reactor.

6nm。 The catalyst is a silica-alumina or / and phosphosilicate molecular sieve catalyst, and their elemental modified product, having a micropore diameter of 0. 3-0. 6nm.

In the method, the matrix material of the catalyst is one or more of silica, alumina or clay. In the method, the temperature of the endothermic zone of the cleavage reaction is from 400 to 700 °C.

In the process described, the temperature difference between the inlet and the outlet of the catalyst in the endothermic zone of the cracking reaction is 50-300. C.

In the process, the hydrocarbons introduced into the endothermic zone of the cracking reaction are methanol to form a product of C4 or higher in the olefin reaction, or / and other C4-C20 hydrocarbons.

In the process, the hydrocarbons introduced into the endothermic zone of the cracking reaction are naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or/and kerosene.

In the process described, the ethylene and propylene containing product produced in the endothermic zone of the cracking reaction is combined with the product formed by the methanol conversion. '

According to the present invention, part of the heat of regeneration in the process of recovering methanol to produce low carbon olefins can be recovered by an endothermic hydrocarbon cracking reaction. The invention is characterized in that, for the process of preparing a low-carbon olefin from methanol in a reaction-regeneration fluidized bed process with continuous reaction characteristics, the regenerated high-temperature catalyst enters a cracking reaction endothermic zone before contacting with methanol, in which the endothermic C ₄ -C _{2 is introduced in the area} . Hydrocarbons are contacted with a high temperature catalyst after regeneration, utilizing hydrocarbon cracking reaction absorption catalysis The heat carried by the agent, after the temperature of the catalyst drops to the temperature required for methanol conversion, enters the methanol conversion reactor. At the same time, the low carbon olefin produced by the cracking reaction can be added to the methanol-derived olefin product.

The present invention provides the following method for recovering partially recovered heat in the process of recovering methanol to produce low carbon olefins: In the process of preparing low carbon olefins by using a fluidized bed process methanol, the methanol raw materials and the catalyst are mixed in a reactor to be fluidized. And converted to a product mixture containing ethylene, propylene and other hydrocarbons at a certain temperature; the catalyst is partially or completely deactivated by carbon deposition after reaction; the gaseous reaction product flows out of the reactor into the separation device, and the deactivated catalyst continuously The reactor flows out into the regenerator for regeneration; the deactivated catalyst is passed through a stripper before entering the regenerator, and the residual hydrocarbons on the catalyst are removed by an inert gas such as water vapor, and then burned in an oxygen-containing atmosphere in the regenerator. Carbon; carbon deposits emit heat, part of which is carried out by the regenerated flue gas, and the other part is taken out by the regenerated catalyst; the catalyst heated to 600-700 ° C in the regenerator is inert to water vapor After the gas removes the residual oxygen, it enters a cracking reaction endothermic zone, and the reaction endothermic zone can be a The separate dense phase reaction section can also be used to transport the catalyst to the upgrading section of the methanol conversion reactor. In the endothermic region of the reaction, the hydrocarbon feedstock is contacted with the regenerated catalyst, and the heat carried by the crack absorption catalyst occurs. The temperature of the endothermic zone of the reaction is 400-70 (TC, after the catalyst flows out of the reaction endothermic zone, the temperature is lowered by 50-300 ° C than the inlet of the endothermic zone to achieve the conversion of methanol to an olefin reactor. The temperature is then passed to a reactor for the conversion of methanol to olefins. The products comprising ethylene and propylene formed in the endothermic zone of the above cracking reaction can be combined into the methanol converted product.

The above catalyst comprises a silica-alumina or/and a phosphosilicate molecular sieve catalyst having a pore diameter of 0.3 to 0.6-nm, such as ZSM-5, ZSM 11, SAP0-34, SAP0-11, etc., and their elemental modifications. Sex product. The above catalyst further comprises a matrix material which is one or more of silica, alumina or clay. The hydrocarbons used in the above reaction endothermic zone have a carbon number of 4-20, which may be a product of C ₄ or more in the methylene formation reaction, or may be other C ₄ _C ₂ . Hydrocarbons, including naphtha, gasoline, condensate, light diesel, hydrogenated tail oil and kerosene. Specific embodiment

The invention is described in detail below by means of examples, but the invention is not limited to the examples.

Example 1

Cracking of butene-2 on a SAP0-34 molecular sieve catalyst. The preparation process of the catalyst is as follows: SAP0—34 (Dalian Institute of Chemical Physics, silicon-aluminum ratio 0.2) mixed with clay, aluminum sol and silica sol (both purchased from Zhejiang Yuda Chemical Co., Ltd.) and dispersed into water slurry After spray molding, the microspheres have a particle size distribution of 20 to 100 microns. The above microspheres were calcined at 600 Torr for 4 hours, which is the catalyst used in this example. The content of SAP0-34 in the catalyst is 30 weight%. The reaction was carried out in a fluidized bed microreactor having an inner diameter of 20 mm. The reaction conditions are as follows: The catalyst loading is 10g, butene-2 (Fushun Petrochemical Company, purity 98%, cis, anti-butene-2 ratio is 1), the feed mass space velocity is

1. Ohr" ¹ , reaction pressure was 0. lMPa. The reaction product was analyzed by Varian CP-3800 gas chromatography, Pona column and hydrogen flame detector, and the sampling time was 2 minutes.

The heat of reaction is calculated from the thermodynamic constants of the starting materials and products. The thermodynamic data of C5 is the average of 10 isomers, olefins, diolefins and cycloalkane isomers. C6 is 12 kinds of terpenes, olefins, diolefins and rings. The average of the alkane isomers. Each substance is assumed to be an ideal gas under the reaction conditions.

O

The conversion reaction results and reaction heat of butene-2 on the molecular sieve catalyst are shown in Table 1. Reaction temperature is

500 ° C. From the data in the table, the selectivity of ethylene and propylene in the anti-O C product was 78.1% under this condition, and the reaction endotherm of the cracking reaction was 471 KJ/Kg under the distribution condition of the product.

Table 1: Butene-2 cracking reaction product and reaction heat in Example 1 (50 CTC)

Product distribution (wt%) CH C ₂ H ₄ C ₂ H ₆ C ₃ H ₆ C3H8 C5 Ce ⁺

0. 25 59. 70 0. 31

A H Q/Kmol)

Reaction endotherm (KJ/Kg) 4. 71*10 ² o

O

c ₆ ⁺ represents a product of ^ and above.

1

0

Example 2:

The procedure described in Example 1 was repeated except that the reaction temperature was 550 ° C.

The conversion reaction results and reaction heat of butene-2 on a molecular sieve catalyst are shown in Table 2. From the data in the table, the selectivity of ethylene and propylene in the reaction product was 82.21% under the conditions, and the reaction endotherm of the cracking reaction was 704 KJ/Kg under the distribution condition of the product.

Table 2: Butene-2 cracking reaction product and reaction heat in Example 2 (550 ° C)

Product distribution (wt%) CH4 C2H C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C5 C ₆

0. 44 54. 91 7. 81 5. 39 3. 14

AH (J/Kmol) 3. 38*10 ⁷

Reaction Endotherm (KJ/Kg) 7. 04*10 ² C _e + means (: ₆ and ( ₆ or more products. Example 3: The procedure described in Example 1 was repeated except that the reaction temperature was 600 ° C.

The conversion reaction results and heat of reaction of butene-2 on a molecular sieve catalyst are shown in Table 3. From the data in the table, the selectivity of ethylene and propylene in the reaction product is 80.97%, under the condition of the product, the cleavage reaction

B

The endothermic reaction was 825 KJ/Kg. Table 3: The butene-2 cracking reaction product and heat of reaction (600 ° C) in Example 3.

Product distribution (wt%) CH ₄ C ₂ HC ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C5 Ce

36, 94 6. 40 1. 69 5. 57

3. 96*10 ⁷

Reaction endotherm (KJ/Kg) 8, 25*10 ²

C _e + means ( ₃ and (: ₆ or more products).

o Example 4:

The cleavage of kerosene on the ZSM-5 molecular sieve catalyst, the preparation procedure and the reaction operation of the catalyst are the same as those in the first embodiment except that the SAP0-34 molecular sieve is replaced by ZSM-5 (Nankai University molecular sieve plant, the ratio of silicon to aluminum is 50), and the raw material is replaced by kerosene. (No. 3 aviation kerosene, Qilu Petrochemical). The heat of reaction calculation was the same as in Example 1. The combustion of kerosene was -7513 kJ. The conversion reaction results and heat of reaction of Kg-kerosene on the molecular sieve catalyst are shown in Table 4. The reaction temperature is 550 ° C. Other thermodynamic functions of kerosene are in the order of twelve iridium. From the data in the table, the selectivity of ethylene and propylene in the reaction product was 28.91% under this condition, and the reaction endotherm of the cracking reaction was 2238 KJ/Kg under the distribution condition of the product. Table ⁴ : Pyrolysis of kerosene in Example 4 Reaction product and heat of reaction (550Ό)

Product distribution (wt%) CH4 C2H C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C4

2. 78 18. 30 11. 22 22. 36 33. 03 Reaction endotherm (KJ/Kg) 22. 38*10 ²

C ₅ + represents and (products of ₅ or more. Example 5:

The procedure described in Example 4 was repeated except that the reaction temperature was 600 ° C.

The conversion reaction results and reaction heat of kerosene on a molecular sieve catalyst are shown in Table 5. The combustion of kerosene is -7513 kj. Kg" ¹ , and other thermodynamic functions of kerosene are measured by n-dodecane. From the data in the table, it is known that The selectivity of ethylene and propylene in the product was 36.97%. Under the distribution condition of the product, the reaction endotherm of the cracking reaction was 2821 KJ/Kg.

Table 5: Kerosene cracking reaction product and reaction heat in Example 5 (600 ° C)

C ₅ ⁺ means (: ₅ and (: ₅ or more products). The methanol-to-olefin conversion unit with a methanol conversion scale of 600,000 tons/year is operated at an average of 300 days per year, and the daily methanol treatment capacity is 2,000 tons. The conversion device adopts a reaction-regeneration fluidized bed process, mainly comprising a methanol conversion reactor and a catalyst regenerator, and a cracking endothermic reactor is arranged on the catalyst transport route from the regenerator to the methanol conversion reactor, the reactor adopts Fluidized bed mode. The regenerated high temperature catalyst first passes through the above-mentioned cracking reaction endothermic zone and then enters the methanol conversion reactor.

The SAP0-34 fluidized catalyst was used (the preparation procedure of the catalyst was the same as in Example 1), and the catalyst circulation amount was 2,000 tons/day. The temperature of the regenerated catalyst (after stripping) was 650 Ό and the temperature was required to drop to 430 ° C before the catalyst entered the methanol conversion reactor.

In the above cracking endothermic reactor, the heat carried by the regenerated catalyst was absorbed by the catalytic cracking of butene-2 (sourced as in Example 1) and allowed to cool to 550 Torr. The catalyst heat capacity is 840 J / (Kg, K), and the heat released by the catalyst during the cooling process is 1.68X103⁄4J/day. The catalyst flows out of the above-mentioned endothermic reactor, and is cooled by the heat of the pipeline to 43 (TC, the heat loss of heat dissipation is 0.02× ^{10 8} KJ/day before entering the methanol conversion reactor. In order to control the heat loss of the pipeline, it is necessary to transport the catalyst after regeneration. The pipeline is properly insulated.

The butene-2 in the cracking reactor was preheated to a feed of 20 CTC at a reaction temperature of 550 °C. The heat capacity of butene-2 was Cp = 1456 J / (Kg - K). According to Example 2, the heat of the butene-2 catalytic cracking reaction was 704 KJ/Kg. The heat absorption per ton of butene-2 from feed to complete reaction is 12. 14X103⁄4J/Kg, the conversion of butene-2 is 75%, and the feed of butene-2 is 184 tons/day. The catalyst temperature was lowered from 650 Torr to 550 °C.

In the above-mentioned reaction process, the amount of heat that can be recovered by the catalytic cracking of the butene-2 is 4.45%, and the heat recovered is used for the catalytic cracking of butene-2, which can increase the yield of ethylene. , propylene 76. 0 tons / day. Comparative example 1 :

The methanol-to-olefin conversion unit with a methanol conversion scale of 600,000 tons/year is treated with an average of 300 days per year and a daily methanol treatment capacity of 2,000 tons. The conversion apparatus adopts a reaction-regeneration fluidized bed process similar to that of Embodiment 8, which mainly comprises a methanol conversion reactor and a catalyst regenerator, but does not provide a cleavage reaction endothermic zone, and the catalyst flows directly from the regenerator to the methanol conversion reaction through a transport route. Device.

The SAP0-34 fluidized catalyst was used (the preparation procedure of the catalyst was the same as in Example 1), and the catalyst circulation amount was 2000 tons/day. The temperature of the regenerated catalyst (after stripping) is 650 Ό, and the catalyst is required before entering the methanol conversion reactor. The temperature drop was 430 °C.

The catalyst is completely cooled by the transfer line to 430 ° C, and the catalyst heat capacity is 840 J / (Kg - K), then the heat loss during heat dissipation is 3.70X10 ⁸ KJ / day.

Claims

A method for recovering heat in a regenerated high-temperature catalyst in a process for preparing a low-carbon olefin from methanol, the method comprising the steps of: first bringing a regenerated high-temperature catalyst into a cracking reaction endothermic zone, and then entering a methanol conversion reaction , where

The temperature of the regenerated high temperature catalyst is from 500 to 800 Torr.

The singularity of the pore size is 0. 3-0. 6nm .

3. The method according to claim 1, wherein the catalyst-derived matrix material is one or more of silica, alumina or clay.

The method according to claim 1, wherein the temperature of the endothermic zone of the cracking reaction is 400 to 700 Torr.

The method according to claim 1, wherein the temperature difference between the inlet and the outlet of the catalyst in the endothermic zone of the cracking reaction is 50 to 300 °C.

6. The method according to claim 1, wherein the hydrocarbon cracking reaction zone forming the olefin introduced into the endothermic reaction of the above C ₄ product is methanol, and / or other C ₄ -C _2. Hydrocarbons.

The method according to claim 1, wherein the hydrocarbon introduced in the endothermic region of the cracking reaction is naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or/and kerosene.

The method according to claim 1, wherein the product produced by the hydrocarbon in the endothermic zone of the cracking reaction is combined into a product obtained by taking a lower olefin from methanol.

9. The method of claim 1 wherein said cleavage reaction endotherm is a separate reaction zone in a methanol conversion unit.

10. The method of claim 1 wherein said cleavage reaction endotherm is a literate section of a methanol conversion reactor.