JP2010501495A - Method for recovering regenerative heat in the process of producing lower olefins from methanol - Google Patents

Abstract

The present invention provides a method for recovering regenerative heat in the process of producing lower olefins from methanol by a fluidized bed process. In this method, the regenerated high-temperature catalyst is introduced into a decomposition reaction endothermic region before contacting with methanol, and brought into contact with hydrocarbons in the endothermic region, and the regenerated catalyst has a decomposition reaction by the hydrocarbons. Heat is recovered and the temperature of the catalyst is lowered to the temperature required for methanol conversion.

Description

TECHNICAL FIELD OF THE INVENTION

  The present invention relates to a method for recovering regenerated heat (or the amount of regenerated heat), and specifically relates to a method for recovering heat generated by a high-temperature catalyst after regeneration in the process of producing a lower olefin from methanol.

  Lower olefins such as ethylene and propylene are basic raw materials for the chemical industry. Usually, ethylene and propylene are mainly produced by steam cracking of hydrocarbons, and the raw materials used include naphtha, light diesel oil, and hydrogenation cracking tail oil. Can be mentioned. In recent years, production costs necessary to obtain ethylene and propylene from the above-mentioned raw materials are constantly increasing as the price of oil increases significantly. In addition, when ethylene and propylene are produced by conventional methods, a high temperature tube furnace decomposition process is mainly used, and energy consumption is relatively high. These factors are driving the development of new processes for olefin production.

The process of producing lower olefins from non-petroleum feedstock is a process path that has recently attracted attention, and among them, synthesis gas is produced from coal or natural gas, converted into methanol, Research and development on the process route to convert to olefin is actively promoted. The process in which methanol (or dimethyl ether produced by dehydration of methanol) selectively produces lower (C ₂ -C ₄ ) olefins on a molecular sieve (or molecular sieve) catalyst is commonly referred to as the MTO process.

  In recent years, a fluidized bed MTO process employing a continuous reaction-regeneration process has attracted attention. The basic principle of the fluidized bed process is as follows. That is, methanol as a raw material is mixed with a catalyst in a reactor, and the catalyst is converted to a mixture containing products such as ethylene and propylene at a constant temperature while fluidizing the catalyst. Thereafter, a carbon deposit is generated on the surface, and part or all of the carbon deposit is deactivated. The gaseous reaction product exits the reactor and enters the separator, and the deactivated catalyst continuously exits the reactor and enters the regenerator for regeneration. That is, after carbon deposits are removed by combustion in an oxygen-containing atmosphere, the process returns to the reactor and comes into contact with the reaction raw material again.

  In the above-described continuous reaction-regeneration fluidized bed process, carbon deposited on the surface of the deactivated catalyst is removed by a high temperature combustion method. Usually, the temperature of the combustion reaction is higher than 600 ° C. and can reach 700 ° C. or higher. If the heat dissipation loss is not calculated, the heat generated by the combustion of the deposited carbon is carried away from the regenerator in two ways. That is, a part is taken out by the exhausted high temperature regenerated combustion exhaust gas (flue gas), and another part is taken out by the regenerated high temperature catalyst.

  On the other hand, the heat extracted by the high temperature regenerative combustion exhaust gas is usually recovered and utilized by a method such as steam production or power generation. For example, US20050238543 A1 discloses a method of recovering heat from regenerated combustion exhaust gas, which is a method of reducing the temperature by regenerating the regenerated combustion exhaust gas a plurality of times, and producing the amount of extracted heat such as steam. It includes using it.

  On the other hand, the heat extracted by the regenerated high-temperature catalyst is often used to supply heat for the reaction. The fluidized bed reaction process is usually used for endothermic reactions such as catalytic cracking of hydrocarbons, but part of the reaction heat is provided by a high temperature catalyst regenerated by a regeneration process. That is, the deactivated catalyst is regenerated and heated by burning the precipitated carbon in an oxygen-containing atmosphere in the regenerator, and then returned to the reactor, and heat is transferred from the regenerator to the reactor. To do. This provides at least some heat of reaction.

  However, such a heat utilization method cannot be applied to the conversion reaction from methanol to olefin. This is because the reaction to convert methanol to olefin is a strong heat release reaction, and the catalyst is heated in the reactor, and the temperature of the catalyst entering the reactor is higher than the temperature of the reaction bed layer. This is because the stability of the reaction temperature can be maintained only when the temperature is low. The preferred temperature for the reaction to convert methanol to lower olefin is 350-600 ° C., which is lower than the regeneration temperature (600-700 ° C.) for burning the charcoaling on the catalyst, ie, the temperature of the catalyst after regeneration. Therefore, in order to meet the conversion reaction requirement from methanol to lower olefins, the regenerated high temperature catalyst must release the heat obtained in the regeneration process and the temperature before the catalyst enters the reactor. Need to go down.

  An object of this invention is to provide the method of collect | recovering the heat | fever of the high temperature catalyst reproduced | regenerated in the manufacture process of the lower olefin from methanol.

  The present inventor completed the present invention through intensive research.

  In the gist of the present invention, a method for recovering the heat of a high-temperature catalyst regenerated in the process of producing a lower olefin from methanol is provided. This method includes a step of first allowing the regenerated high-temperature catalyst to enter the cracking reaction endothermic region, and then entering the methanol conversion reactor, in which the hydrocarbons are introduced into the cracking reaction endothermic region. In this method, the catalyst is brought into contact with the regenerated high temperature catalyst to cause a decomposition reaction, and the temperature of the regenerated high temperature catalyst is 500 to 800 ° C.

  In a preferred form of the invention, the catalyst used is an aluminosilicate zeolite or / and a phosphosilicate molecular sieve catalyst and their element-modified products, the micropores having a diameter of 0.3 to 0.6 nm (or pore size). ).

  In another preferred form of the invention, the matrix material of the catalyst is one or more selected from silicon oxide, alumina or clay.

  In a preferred embodiment of the present invention, the temperature of the decomposition reaction endothermic region is 400 to 700 ° C.

  In another preferred embodiment of the present invention, the temperature difference of the catalyst between the inlet and outlet of the decomposition reaction endothermic region is 50-300 ° C.

In a preferred form of the invention, the hydrocarbons introduced into the cracking reaction endothermic region are C ₄ or higher products or / and other C ₄ -C ₂₀ hydrocarbons in the methanol to olefin reaction.

  In another preferred form of the invention, the hydrocarbons introduced into the cracking reaction endothermic zone are naphtha, gasoline, gas condensate, light diesel oil, hydrogenation. Tail oil (hydrogenation tail oil) and / or kerosene.

In a preferred form of the invention, the hydrocarbon product in the cracking reaction endothermic region is combined with the product obtained from the reaction of methanol to lower olefins.

In a preferred embodiment of the present invention, the decomposition reaction endothermic region is an independent reaction region (or reaction stage) in the methanol converter.

In a preferred form of the invention, the cracking reaction endothermic zone is the riser stage (or riser or riser zone) of the methanol conversion reactor.

According to the method of the present invention, a part of heat brought out by the catalyst regenerated in the process of producing the lower olefin from methanol can be recovered, and after the regeneration so as to satisfy the temperature requirement of the conversion reaction from methanol to the lower olefin. The temperature of the catalyst can be adjusted.

  In order to achieve the above object, in the method for recovering regenerative heat in the process of producing lower olefins from methanol according to the present invention, the regenerated high-temperature catalyst is led to a decomposition reaction endothermic region, and in this endothermic region, hydrocarbons The catalytic cracking reaction absorbs the heat of the catalyst, lowers the temperature of the catalyst, and then introduces the catalyst into the methanol conversion reactor.

  In the above-described method, the catalyst used is an aluminosilicate zeolite or / and a phosphosilicate molecular sieve catalyst, and their element-modified products, and the pore diameter is 0.3 to 0.6 nm.

  In the above method, the matrix material of the catalyst is one or more selected from silicon oxide, alumina or clay.

  In the above method, the temperature of the decomposition reaction endothermic region is 400 to 700 ° C.

  In the above method, the temperature difference of the catalyst between the inlet and outlet of the decomposition reaction endothermic region is 50 to 300 ° C.

In the above-described method, the hydrocarbons introduced into the decomposition reaction endothermic region are C ₄ or higher products in the production reaction from methanol to olefins and / or other C ₄ -C ₂₀ hydrocarbons.

In the above-mentioned method, hydrocarbons introduced into the endothermic region of decomposition reaction are naphtha, gasoline, gas condensate, light diesel oil, hydrogenated tail oil (hydrogenation). tail oil) and / or kerosene.

In the above process, the product comprising ethylene and propylene produced in the cracking reaction endothermic region is combined with the product produced by the conversion of methanol.

In the present invention, a part of regeneration heat (or part of regeneration heat) in the process of producing a lower olefin from methanol can be recovered by an endothermic hydrocarbon decomposition reaction. The present invention has the following features. That is, in a continuous reaction type reaction-regeneration fluidized bed process in which lower olefins are produced from methanol, the regenerated high-temperature catalyst enters the decomposition reaction endothermic region before contacting with methanol, and C ₄ -C _{20 is} contained in this endothermic region. When hydrocarbons are introduced and contacted with the regenerated high-temperature catalyst, the heat carried by the catalyst is recovered by the decomposition reaction of the hydrocarbons, and the temperature of the catalyst is lowered to meet the temperature requirement for methanol conversion The catalyst is introduced into the methanol conversion reactor. At the same time, the lower olefin produced by the cracking reaction can be added to the olefin product produced from methanol.

  The present invention provides the following method for recovering a part of regeneration heat in the process of producing a lower olefin from methanol. That is, in the process of producing lower olefins from methanol using a fluidized bed process, the methanol raw material and the catalyst are mixed in the reactor to fluidize the catalyst, and ethylene, propylene and other hydrocarbons are maintained at a constant temperature. To a product mixture containing The catalyst generates a carbon deposit on the surface (or carbon is deposited) by the reaction, and part or all of the catalyst is deactivated. The gaseous reaction product flows out of the reactor and enters the separation unit, and the deactivated catalyst continuously flows out of the reactor and enters the regenerator for regeneration. The deactivated catalyst passes through a stripping device before entering the regenerator, and 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. The carbon deposit is removed. Heat is released by the combustion of the carbon deposit, part of that heat is received by the regenerated flue gas, and another part is received by the regenerated catalyst. The catalyst heated to 600 to 700 ° C. in the regenerator enters the decomposition reaction endothermic region after residual oxygen is removed by an inert gas such as water vapor. This reaction endothermic zone may be an independent dense (or dense) -phase reaction stage (or reaction zone) and at the same time a riser stage that transports the catalyst to the methanol conversion reactor. In this reaction endothermic region, the hydrocarbon raw material contacts the regenerated catalyst and undergoes a decomposition reaction, and absorbs heat carried by the catalyst. The temperature of the reaction endothermic region is 400 to 700 ° C., and after the catalyst flows out of the reaction endothermic region, the temperature is 50 to 300 ° C. lower than the inlet of the endothermic region, and the conversion reaction from methanol to olefin is required The temperature has been reached. The catalyst then enters a reactor for converting methanol to olefins. The product containing ethylene and propylene produced in the above-mentioned decomposition reaction endothermic region may be combined with the product of methanol conversion.

The above catalyst is an aluminosilicate zeolite having a micropore diameter of 0.3 to 0.6 nm and / or a phosphosilicate molecular sieve catalyst (for example, ZSM-5, ZSM-11, SAPO-34, SAPO-11, etc.), and , Including these elemental modified products. The catalyst further includes a matrix material that is one or more of silicon oxide, alumina, or clay. In the reaction endothermic region, the hydrocarbon used has a carbon number in the range of 4 to 20, and the hydrocarbon may be a product of C ₄ or higher in the methanol-to-olefin production reaction, and other C ₄ -C _It may be ₂₀ hydrocarbons. Such hydrocarbons include naphtha, gasoline, gas condensate, light diesel oil, hydrogenation tail oil and kerosene. .

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
Decomposition of butylene-2 with SAPO-34 molecular sieve catalyst The production process of the catalyst is as follows. That is, SAPO-34 (Dalian Chemical Physics Laboratory, silicon aluminum ratio is 0.2), clay, aluminum sol and silica sol (all purchased from Zhejiang Yuda Chemical Engineering Co. Ltd) are mixed and dispersed in water to make a slurry. By spray molding, microspheres having a particle size distribution of 20 to 100 microns were formed. The above microspheres were calcined at 600 ° C. for 4 hours to obtain a catalyst used in this example. In the catalyst, the content of SAPO-34 is 30% by weight. The reaction is carried out in a fluidized bed micro-reactor with an inner diameter of 20 mm. The reaction conditions are as follows. That is, the catalyst loading is 10 g, butylene-2 (Fushun Petrochemical Co., purity 98%, cis-transbutylene-2 ratio is 1) feed mass space velocity (WHSV) is 1.0 hr ^{− 1} and the reaction pressure is 0.1 MPa. The reaction products were analyzed on a Varian CP-3800 gas chromatograph equipped with a Pona column and FID (hydrogen flame detector). The sampling time was 2 minutes.

The reaction heat is obtained by calculation from the thermodynamic constants of the raw material and the product. In the calculation, the C5 hydrocarbon thermodynamic data is the average of 10 hydrocarbons (alkanes, olefins, dienes, cycloalkane isomers), and C6 thermodynamic data is 12 C ₆ thermodynamic data. It is an average value of hydrocarbons (alkane, olefin, diene, cycloalkane isomers). Each substance is assumed to be an ideal gas under the reaction conditions.

  Table 1 shows the conversion reaction results and heat of reaction of butylene-2 with molecular sieve catalysts. The reaction temperature was 500 ° C. As can be seen from the data in the table, the selectivity of ethylene and propylene in the reaction product under this reaction condition is 78.1%, and the reaction endotherm of the decomposition reaction is 471 KJ / Kg under this product distribution condition.

Example 2
The reaction was performed under the same conditions as in Example 1 except that the reaction temperature was 550 ° C.

Table 2 shows the conversion reaction results and heat of reaction of butylene-2 with molecular sieve catalysts. As can be seen from the data in the table, the selectivity of ethylene and propylene in the reaction product under this reaction condition is 82.21%, and the reaction endotherm of the decomposition reaction is 704 KJ / Kg under the distribution condition of this product.

Example 3
The reaction was conducted under the same conditions as in Example 1 except that the reaction temperature was 600 ° C.

  Table 3 shows the results of conversion reaction of butylene-2 by molecular sieve catalyst and the heat of reaction. As can be seen from the data in the table, the selectivity of ethylene and propylene in the reaction product under this reaction condition is 80.97%, and the reaction endotherm of the decomposition reaction is 825 KJ / Kg under the distribution condition of this product.

Example 4
Decomposition of kerosene with ZSM-5 molecular sieve catalyst
SAPO-34 molecular sieve catalyst is replaced with ZSM-5 (The molecular sieve plant of Nankai University, silicon-aluminum ratio is 50), and the raw material is kerosene (No. 3 aviation kerosene, Qilu Petrochemical Co.) The production process and reaction operation of the catalyst are the same as in Example 1 except for the change to. The calculation method of the heat of reaction was also the same as in Example 1, and the burning enthalpy of kerosene was -7513 KJ.Kg ^-1 .

  Table 4 shows the conversion reaction results and heat of reaction of kerosene with a molecular sieve catalyst. The reaction temperature was 550 ° C. The other thermodynamic functions of kerosene are calculated in n-dodecane. As can be seen from the data in the table, the selectivity of ethylene and propylene in the reaction product under this reaction condition is 28.91%, and the reaction endotherm is 2238 KJ / Kg under this product distribution condition.

Example 5
The reaction was performed under the same conditions as in Example 4 except that the reaction temperature was 600 ° C.

Table 5 shows the conversion reaction results and heat of reaction of kerosene with molecular sieve catalyst. The burning enthalpy of kerosene was -7513KJ.Kg- ¹ . The other thermodynamic functions of kerosene are calculated in n-dodecane. As can be seen from the data in the table, the selectivity of ethylene and propylene in the reaction product under this reaction condition is 36.97% and the reaction endotherm is 2821 KJ / Kg under this product distribution condition.

Example 6
Table 6 shows the conversion reaction results and heat of reaction of gasoline with ZSM-5 molecular sieve catalyst. The production process and reaction operation of the catalyst are the same as in Example 4 except that the reaction raw material is changed to gasoline (Fushun Petrochemical Co., olefin content is 40%). The reaction temperature was 640 ° C. The thermodynamic function of gasoline was calculated by the average value of various pentenes. As can be seen from the data in the table, the yield of ethylene and propylene in the reaction product is 44.01% under the reaction conditions, and the reaction endotherm of the decomposition reaction is 361 KJ / Kg under the distribution conditions of the product.

Example 7
The reaction was performed under the same conditions as in Example 6 except that the reaction temperature was 610 ° C.

  Table 7 shows the conversion reaction results and heat of reaction of gasoline with molecular sieve catalyst. The thermodynamic function of gasoline was calculated by the average value of various pentenes. As can be seen from the data in the table, the yield of ethylene and propylene in the reaction product is 39.68% under the reaction conditions, and the reaction endotherm of the decomposition reaction is 367 KJ / Kg under the distribution conditions of the product.

Example 8
An apparatus for producing olefins from methanol, which has a methanol conversion scale of 600,000 tons / year, worked normally for an average of 300 days every year, and the daily methanol throughput was set at 2000 tons. This conversion apparatus utilizes a reaction-regeneration fluidized bed process, which mainly includes a methanol conversion reactor and a catalyst regenerator, and a cracking endothermic reactor is provided on the catalyst transport route from the regenerator to the methanol conversion reactor. This reactor uses a fluidized bed system. The regenerated high-temperature catalyst first passes through the above-described decomposition endothermic reactor, and is then introduced into the methanol conversion reactor.

  A SAPO-34 fluid catalyst (the catalyst production process is the same as in Example 1) was used, and the catalyst circulation rate was 2000 tons / day. The temperature of the regenerated catalyst (stripping) is 650 ° C., and it is necessary to lower the temperature of the catalyst to 430 ° C. before entering the methanol conversion reactor.

In the above-described decomposition endothermic reactor, heat of the regenerated catalyst was absorbed through catalytic cracking of butylene-2 (derived from the same as in Example 1), and the temperature of the catalyst was lowered to 550 ° C. The heat capacity of the catalyst was 840 J / (Kg · K), and the amount of heat released from the catalyst during the cooling process was 1.68 × 10 ⁸ KJ / day. Prior to introducing the catalyst from the endothermic reactor into the methanol conversion reactor, the catalyst was passed through a pipeline, and the catalyst temperature was lowered to 430 ° C. by heat exchange. The heat loss due to heat exchange was 2.02 × 10 ⁸ KJ / day. In order to control the heat dissipation loss due to the pipe line, it is necessary to appropriately maintain the temperature of the pipe line that transports the regenerated catalyst.

In the cracking reactor, butylene-2 was preheated to 200 ° C. and supplied, and the reaction temperature was 550 ° C. The heat capacity of butylene-2 was Cp = 1456 J / (Kg · K), and based on Example 2, the catalytic decomposition heat value of butylene-2 was 704 KJ / Kg. One ton of butylene-2 has an endotherm of 12.14 × 10 ⁵ KJ / Kg from the supply to the completion of the reaction, and conversion of butylene-2 to once-through (or once-through) is 75%. It is. Then, when the supply amount of butylene-2 is 184 tons / day, the temperature of the catalyst can be lowered from 650 ° C. to 550 ° C.

In the above reaction process, the amount of heat that can be recovered by catalytic cracking of butylene-2 is 45% of the amount of heat that the catalyst after regeneration has, and the amount of heat that is recovered is used for catalytic cracking of butylene-2. Production of propylene can be increased by 76.0 tons / day.

Comparative Example 1
The olefin production equipment from methanol with a methanol conversion scale of 600,000 tons / year worked normally for 300 days on average every year, and the daily methanol throughput was set at 2000 tons. The conversion apparatus uses a reaction-regeneration fluidized bed process similar to that in Example 8, and mainly includes a methanol conversion reactor and a catalyst regenerator, but does not have a decomposition reaction endothermic region, and the catalyst is transported. Through the line, it flows directly from the regenerator to the methanol conversion reactor.

  A SAPO-34 fluid catalyst (the catalyst production process is the same as in Example 1) was used, and the catalyst circulation rate was 2000 tons / day. The temperature of the regenerated catalyst (stripping) is 650 ° C., and it is necessary to lower the catalyst temperature before entering the methanol conversion reactor to 430 ° C.

The catalyst was cooled down to 430 ° C. by completely releasing heat through the transport line. The heat capacity of the catalyst was 840 J / (Kg · K), and the heat loss of the catalyst due to heat exchange during the cooling process was 3.70 × 10 ⁸ KJ / day.

Claims (10)

In the process of producing a lower olefin from methanol, a method for recovering heat from the regenerated high temperature catalyst,
Including the step of first allowing the high-temperature catalyst after regeneration to enter the decomposition reaction endothermic region and then entering the methanol conversion reactor;
In the step, hydrocarbons are introduced into the decomposition reaction endothermic region, and contacted with the regenerated high-temperature catalyst to cause a decomposition reaction;
The method according to claim 1, wherein the temperature of the regenerated high temperature catalyst is 500 to 800 ° C.   The catalyst according to claim 1, wherein the catalyst is an aluminosilicate zeolite or / and a phosphosilicate molecular sieve catalyst, and an element-modified product thereof, and the pore diameter is 0.3 to 0.6 nm. Method.   2. The method according to claim 1, wherein a substrate material of the catalyst is one or more selected from silicon oxide, alumina, and clay.   The method according to claim 1, wherein the temperature of the decomposition reaction endothermic region is 400 to 700 ° C.   The method according to claim 1, wherein the temperature difference between the inlet and the outlet of the decomposition reaction endothermic region of the catalyst is 50 to 300 ° C. The hydrocarbons introduced into the endothermic region of the cracking reaction are products of C ₄ or higher in the production reaction from methanol to olefins, and / or other C ₄ -C ₂₀ hydrocarbons. The method of claim 1.   2. The method according to claim 1, wherein the hydrocarbons introduced into the decomposition reaction endothermic region are naphtha, gasoline, gas condensate, light diesel oil, hydrogenated tail oil or / and kerosene.   2. The method according to claim 1, wherein a product produced from the hydrocarbons in the decomposition reaction endothermic region is combined with a reaction product obtained by production of methanol into a lower olefin.   2. The method according to claim 1, wherein the endothermic reaction area for decomposition reaction is an independent reaction area in a methanol converter.   The process according to claim 1, characterized in that the decomposition reaction endothermic region is a riser stage of a methanol conversion reactor.