CN216987593U - Axial-radial flow multi-step feeding fixed bed reactor - Google Patents
Axial-radial flow multi-step feeding fixed bed reactor Download PDFInfo
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Abstract
The utility model provides a fixed bed reactor with axial-radial flow multi-step feeding, which comprises a shell and at least 2 sections of catalyst bed layers arranged in the shell; the shell comprises at least 1 air inlet, 2-8 liquid inlets and at least 1 product outlet; the liquid inlet is positioned on the side wall of the shell between every 2 sections of catalyst bed layers; an axial gas guide pipe is arranged in the center of the catalyst bed layer; the tail end of the axial air duct is closed, and air outlet holes are uniformly distributed in the side wall of the axial air duct. The fixed bed reactor provided by the utility model is particularly suitable for preparing paraxylene by carbon dioxide hydrogenation coupled toluene alkylation, enhances the reaction process, and achieves the purposes of low catalyst volume, high single-pass conversion rate and low byproduct selectivity.
Description
Technical Field
The utility model belongs to the technical field of reactor design, relates to a fixed bed reactor, and particularly relates to a fixed bed reactor with axial-radial flow multi-step feeding.
Background
Carbon dioxide is a greenhouse gas, and the effective utilization of the carbon dioxide has important strategic significance on relieving the energy crisis and achieving the aim of 'carbon neutralization'. Paraxylene is one of basic organic chemical raw materials in petrochemical industry and is mainly used for producing synthetic resin, synthetic fiber and synthetic rubber. The traditional method for obtaining p-xylene is mainly prepared by naphtha catalytic reforming, toluene isomerization and toluene-methanol alkylation transfer which is commonly used in recent years, but the methods all depend on fossil resources. Therefore, the cheap carbon dioxide is converted into the high-added-value product p-xylene, so that the resource utilization of the carbon dioxide can be realized, huge economic benefits are generated, the carbon emission can be indirectly realized, and the method has important research and development significance and good industrial application prospects.
At present, in a plurality of technologies for preparing aromatic hydrocarbon by carbon dioxide, a two-step synthesis technology for preparing methanol by catalytic hydrogenation of carbon dioxide and then generating paraxylene by direct alkylation reaction of the obtained methanol and toluene attracts particular attention. For example, CN 110743609a discloses a combined catalyst for preparing xylene by carbon dioxide hydrogenation coupled with toluene alkylation, which can significantly improve selectivity and production efficiency of para-xylene; CN111215084A discloses a special catalyst for preparing aromatic hydrocarbon by carbon dioxide one-step hydrogenation, and the catalyst is mainly Fe modified or not modified by nano metal oxide2O3And ZSM-5 molecular sieve, and has the advantages of good reaction stability, high aromatic selectivity and the like. However, most of the above studies have focused on designing a catalyst with high activity, high selectivity and high stability, and there is no concern about the design and structure optimization of the apparatus for carrying out the reaction process, i.e., the reactor.
Therefore, how to provide a reactor for preparing paraxylene, which is particularly suitable for preparing paraxylene by carbon dioxide hydrogenation coupled toluene alkylation, strengthens the reaction process, and achieves the aims of low catalyst volume, high single-pass conversion rate and low byproduct selectivity becomes a problem urgently needed to be solved by technical personnel in the field at present.
SUMMERY OF THE UTILITY MODEL
Aiming at the defects in the prior art, the utility model aims to provide the fixed bed reactor with axial-radial flow multi-step feeding, which is particularly suitable for preparing p-xylene by carbon dioxide hydrogenation coupled with toluene alkylation, strengthens the reaction process, and achieves the purposes of low catalyst volume, high single-pass conversion rate and low byproduct selectivity.
In order to achieve the purpose, the utility model adopts the following technical scheme:
the utility model provides a fixed bed reactor with axial radial flow multi-step feeding, which comprises a shell and at least 2 sections of catalyst beds arranged in the shell, such as 2 sections, 3 sections, 4 sections or 5 sections, but not limited to the values listed, and other values in the range of the values are also applicable.
The housing comprises at least 1 gas inlet, 2-8 liquid inlets and at least 1 product outlet, wherein the number of gas inlets may be 1, 2 or 3, the number of liquid inlets may be 2, 3, 4, 5, 6, 7 or 8, and the number of product outlets may be 1, 2 or 3, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
The liquid inlet is positioned on the side wall of the shell between every 2 sections of catalyst bed layers.
And an axial gas guide pipe is arranged in the center of the catalyst bed layer.
The tail end of the axial air duct is closed, and air outlet holes are uniformly distributed in the side wall of the axial air duct.
The axial gas guide pipe is arranged in the center of the multi-section catalyst bed layer, and the gas outlet holes are uniformly distributed on the side wall of the axial gas guide pipe, so that the radial flow of reaction materials in the catalyst bed layer is realized, the reaction process is strengthened, the catalyst bed layer is suitable for high-space-velocity operation, the conversion rate of raw materials is improved, and the selectivity of byproducts is reduced.
In addition, the side wall of the reactor shell is provided with the plurality of liquid inlets, so that the multi-step feeding operation is realized, and the reaction can be carried out under the optimal dynamic condition close to thermodynamic equilibrium by combining the reasonable control of the materials and the temperature of the reactor, so that the conversion rate of the raw materials and the selectivity of a target product are further improved.
Preferably, a gas guide zone is also arranged between the side wall of the catalyst bed layer and the shell.
Preferably, the catalyst bed is closed at both the top and bottom.
Preferably, the air conducting area is closed at the top and is opened at the bottom.
The gas guide zone is arranged, so that gas-phase materials smoothly enter the next section of catalyst bed layer after flowing through the previous section of catalyst bed layer in a radial direction, the top and the bottom of the catalyst bed layer and the top of the gas guide zone are sealed, and the gas-phase materials are prevented from back mixing or flowing through the catalyst bed layer in an axial direction.
Preferably, the number of the air inlets is 1, and the air inlets are arranged at the top of the shell.
Preferably, the number of the product outlets is 1, and the product outlets are arranged at the bottom of the shell.
Preferably, the liquid inlet is further connected with an atomizing nozzle, and the outlet direction of the atomizing nozzle is opposite to the flow direction of the gas phase in the reactor, so as to promote the sufficient mixing and reaction between the materials.
Preferably, the cross-section of the housing is circular with a diameter of 0.5-2m, for example 0.5m, 0.6m, 0.8m, 1m, 1.2m, 1.4m, 1.6m, 1.8m or 2m, but is not limited to the values listed, and other values not listed in this range are equally applicable.
Preferably, the height of the housing is 6-20m, for example 6m, 8m, 10m, 12m, 14m, 16m, 18m or 20m, but is not limited to the values listed, and other values not listed in this range are equally applicable.
Preferably, the axial airway tube has a cross-sectional diameter of 0.1 to 0.4m, and may for example be 0.1m, 0.15m, 0.2m, 0.25m, 0.3m, 0.35m or 0.4m, but is not limited to the values recited, and other values not recited within this range are equally applicable.
In the utility model, the diameter of the cross section of the axial air duct needs to be controlled within a reasonable range. When the diameter of the cross section is less than 0.1m, the axial gas guide pipe is too thin, the transmission resistance of gas-phase materials in the gas guide pipe is large, and the gas-phase materials are not suitable for high-airspeed operation; when the diameter of the cross section is more than 0.4m, the axial gas guide pipe is too thick, so that too much catalyst space is occupied, and the reaction is not favorably carried out sufficiently.
Preferably, the axial airway tube has a sidewall opening ratio of 5% to 20%, for example 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%, but not limited to the values recited, and other values not recited within this range are equally applicable.
Preferably, the aperture of the outlet is 2-16mm, and may be, for example, 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm or 16mm, but is not limited to the values recited, and other values not recited within the range are equally applicable.
Preferably, the spacing between each 2 catalyst beds is 400-800mm, and may be, for example, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm, 700mm, 750mm or 800mm, but is not limited to the values recited, and other values not recited within the range are equally applicable.
Preferably, the height of the 1 st stage catalyst bed, as counted from the top of the shell, is from 1.5 to 3 times the height of the remaining catalyst beds, for example 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3 times, but is not limited to the values recited, and other values not recited in this range of values are equally applicable.
The utility model adopts a multi-stage catalyst bed, wherein the inside of the 1 st stage catalyst bed mainly generates carbon dioxide hydrogenation reaction, and the reaction heat is delta H1Under the condition of-49.143 KJ/mol, the other catalyst bed layer is mainly subjected to toluene alkylation reaction, and the reaction heat delta H2The heat of reaction of the latter is about 3.5 times that of the former, and the degree of alkylation reaction is slightly higher than that of hydrogenation reaction. Therefore, the height of the catalyst bed layer at the 1 st section is 1.5-3 times of the height of the rest catalyst bed layers, so that the temperature of the toluene alkylation reaction can be uniformly distributed, the phenomena of overtemperature and coking of the catalyst bed layers are prevented, the reaction rate is controlled, and the full coupling between the carbon dioxide hydrogenation reaction and the toluene alkylation reaction is ensured.
Preferably, counting is started from the top of the shell, and the top end of the axial gas guide pipe in the center of the 1 st section of the catalyst bed layer extends out of the catalyst bed layer and is connected with the gas inlet.
Compared with the prior art, the utility model has the following beneficial effects:
(1) according to the fixed bed reactor provided by the utility model, the axial gas guide pipe is arranged in the center of the multi-section catalyst bed layer, and the gas outlet holes are uniformly distributed on the side wall of the axial gas guide pipe, so that the radial flow of reaction materials in the catalyst bed layer is realized, the reaction process is strengthened, the fixed bed reactor is suitable for high-airspeed operation, the conversion rate of raw materials is improved, and the selectivity of byproducts is reduced;
(2) according to the fixed bed reactor provided by the utility model, the plurality of liquid inlets are formed in the side wall of the reactor shell, so that multi-step feeding operation is realized, and the reaction can be carried out under the optimal dynamic condition close to thermodynamic equilibrium by combining reasonable control of materials and the temperature of the reactor, so that the conversion rate of raw materials and the selectivity of a target product are further improved.
Drawings
FIG. 1 is a schematic diagram of a fixed bed reactor configuration with axial radial flow multi-step feeding as provided in examples 1-5;
FIG. 2 is a schematic diagram of a fixed bed reactor configuration with axial radial flow multi-step feeding provided in example 6;
FIG. 3 is a schematic diagram of the structure of a fixed bed reactor provided in comparative example 1;
FIG. 4 is a schematic diagram of the structure of the fixed bed reactor provided in comparative example 2.
Wherein: 10-a housing; 20-catalyst bed layer; 21-1 st section catalyst bed layer; 22-2 nd section catalyst bed layer; 23-3 rd section catalyst bed layer; 30-an air inlet; 40-liquid inlet; 50-a product outlet; 60-axial airway; 61-1 st section axial air guide pipe; 62-2 nd section axial air guide pipe; 63-3 rd section axial air guide pipe; 70-gas conducting zone.
Detailed Description
It is to be understood that in the description of the present invention, the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the present invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner and therefore are not to be construed as limiting the utility model.
It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The technical scheme of the utility model is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
This embodiment provides a fixed bed reactor of axial radial flow multistep feeding, as shown in fig. 1, fixed bed reactor include casing 10 with set up in the inside 3 sections catalyst bed layers 20 of casing 10, casing 10 includes 1 air inlet 30, 4 inlet 40 and 1 product export 50, inlet 40 is located the casing 10 lateral wall between every 2 sections catalyst bed layers 20, catalyst bed layer 20's central authorities are provided with axial air duct 60, axial air duct 60's end is sealed, and the lateral wall equipartition has the venthole. The 1 st section axial air guide pipe 61 extends out of the 1 st section catalyst bed layer 21 from the top end and is connected with the air inlet 30.
In this embodiment, a gas guiding area 70 is further disposed between the sidewall of the catalyst bed 20 and the housing 10, the top and the bottom of the catalyst bed 20 are both closed, the top of the gas guiding area 70 is closed, and the bottom is open.
In this embodiment, the cross section of the casing 10 is circular, the diameter of the cross section is 1m, and the height of the casing 10 is 18 m; the diameter of the cross section of the axial air duct 60 is 0.3m, the opening rate of the side wall is 15%, and the aperture of the air outlet hole is 2 mm; the height of the 1 st section of catalyst bed layer 21 is 3 times of the height of the rest catalyst bed layers, and the spacing distance between every two 2 sections of catalyst bed layers is 600 mm.
Example 2
The embodiment provides a fixed bed reactor of axial radial flow multistep feeding, as shown in fig. 1, fixed bed reactor include casing 10 with set up in 3 sections catalyst bed 20 inside casing 10, casing 10 includes 1 air inlet 30, 8 inlet 40 and 1 product export 50, inlet 40 is located the 10 lateral walls of casing between every 2 sections catalyst bed 20, catalyst bed 20's central authorities are provided with axial air duct 60, the end of axial air duct 60 is sealed, and the lateral wall equipartition has the venthole. The 1 st section axial air guide pipe 61 extends out of the 1 st section catalyst bed layer 21 from the top end and is connected with the air inlet 30.
In this embodiment, a gas guiding area 70 is further disposed between the sidewall of the catalyst bed 20 and the housing 10, the top and the bottom of the catalyst bed 20 are both closed, the top of the gas guiding area 70 is closed, and the bottom is open.
In this embodiment, the cross section of the housing 10 is circular, the diameter of the cross section is 2m, and the height of the housing 10 is 14 m; the diameter of the cross section of the axial air duct 60 is 0.4m, the opening rate of the side wall is 10%, and the aperture of the air outlet hole is 16 mm; the height of the 1 st section of catalyst bed layer 21 is 2 times of the height of the rest catalyst bed layers, and the spacing distance between every two 2 sections of catalyst bed layers is 800 mm.
Example 3
The embodiment provides a fixed bed reactor of axial radial flow multistep feeding, as shown in fig. 1, fixed bed reactor include casing 10 with set up in 3 sections catalyst bed 20 inside casing 10, casing 10 includes 1 air inlet 30, 6 inlet 40 and 1 product export 50, inlet 40 is located the 10 lateral walls of casing between every 2 sections catalyst bed 20, catalyst bed 20's central authorities are provided with axial air duct 60, the end of axial air duct 60 is sealed, and the lateral wall equipartition has the venthole. The 1 st section axial air guide pipe 61 extends out of the 1 st section catalyst bed layer 21 from the top end and is connected with the air inlet 30.
In this embodiment, a gas guiding area 70 is further disposed between the sidewall of the catalyst bed 20 and the housing 10, the top and the bottom of the catalyst bed 20 are both closed, the top of the gas guiding area 70 is closed, and the bottom is open.
In this embodiment, the cross section of the housing 10 is circular, the diameter of the cross section is 0.5m, and the height of the housing 10 is 6 m; the diameter of the cross section of the axial air duct 60 is 0.1m, the opening rate of the side wall is 5%, and the aperture of the air outlet hole is 10 mm; the height of the 1 st section of catalyst bed layer 21 is 2 times of the height of the rest catalyst bed layers, and the spacing distance between every two 2 sections of catalyst bed layers is 400 mm.
Example 4
This embodiment provides a fixed bed reactor with axial-radial flow multi-step feeding, except that the heights of the 1 st section of catalyst bed layer 21, the 2 nd section of catalyst bed layer 22 and the 3 rd section of catalyst bed layer 23 are all changed to 5m, that is, the height of the 1 st section of catalyst bed layer 21 is the same as the heights of the rest of catalyst bed layers, and the rest of the structure and conditions are the same as those in embodiment 1, so that the details are not described herein.
Example 5
This example provides a fixed bed reactor with axial-radial flow multi-step feeding, except that an atomizing nozzle (not shown in fig. 1) is connected to the liquid inlet 40, and the outlet direction of the atomizing nozzle is opposite to the flow direction of the gas phase in the reactor, and the rest of the structure and conditions are the same as those in example 1, and thus the detailed description thereof is omitted.
Example 6
The embodiment provides a fixed bed reactor of axial radial flow multistep feeding, as shown in fig. 2, fixed bed reactor include casing 10 with set up in 2 sections catalyst bed 20 inside casing 10, casing 10 includes 1 air inlet 30, 2 inlet 40 and 1 product export 50, inlet 40 is located the 10 lateral walls of casing between every 2 sections catalyst bed 20, catalyst bed 20's central authorities are provided with axial air duct 60, the end of axial air duct 60 is sealed, and the lateral wall equipartition has the venthole. The 1 st section axial air guide pipe 61 extends out of the 1 st section catalyst bed layer 21 from the top end and is connected with the air inlet 30.
In this embodiment, a gas guiding area 70 is further disposed between the sidewall of the catalyst bed 20 and the housing 10, the top and the bottom of the catalyst bed 20 are both closed, the top of the gas guiding area 70 is closed, and the bottom is open.
In this embodiment, the cross section of the casing 10 is circular, the diameter of the cross section is 1m, and the height of the casing 10 is 18 m; the diameter of the cross section of the axial air duct 60 is 0.3m, the opening rate of the side wall is 10%, and the aperture of the air outlet hole is 10 mm; the height of the 1 st section of catalyst bed 21 is 2 times of the height of the 2 nd section of catalyst bed 22, and the spacing distance between the 2 sections of catalyst beds is 600 mm.
Comparative example 1
This comparative example provides a fixed bed reactor, as shown in fig. 3, fixed bed reactor include casing 10 with set up in the inside catalyst bed 20 of casing 10, casing 10 includes 1 air inlet 30, 2 inlet 40 and 1 product export 50, inlet 40 is located the 10 lateral walls of casing above catalyst bed 20, catalyst bed 20's central authorities are provided with axial air duct 60, axial air duct 60's end is sealed, and the lateral wall equipartition has the venthole.
In this comparative example, a gas guiding zone 70 is further disposed between the side wall of the catalyst bed 20 and the shell 10, the top and the bottom of the catalyst bed 20 are both closed, and the top and the bottom of the gas guiding zone 70 are both closed.
In the present comparative example, the cross section of the housing 10 is circular, the diameter of the cross section is 1m, and the height of the housing 10 is 18 m; the height of the catalyst bed 20 is 10 m.
Comparative example 2
This comparative example provides a fixed bed reactor, as shown in fig. 4, the fixed bed reactor includes casing 10 and sets up in 3 sections catalyst bed 20 inside the casing 10, casing 10 includes 1 air inlet 30, 4 inlet 40 and 1 product export 50, inlet 40 is located the casing 10 lateral wall between every 2 sections catalyst bed 20.
In the present comparative example, the cross section of the housing 10 is circular, the diameter of the cross section is 1m, and the height of the housing 10 is 18 m; the height of the 1 st section of catalyst bed layer 21 is 2 times of the height of the rest catalyst bed layers, and the spacing distance between every two 2 sections of catalyst bed layers is 600 mm.
Application example 1
The application example uses the fixed bed reactor provided in example 1 to prepare paraxylene, and the preparation method comprises the following steps:
(1) the mixed gas of carbon dioxide and hydrogen is mixed for 6000h through the gas inlet 30 according to the molar ratio of 1:6-1The catalyst is the catalyst disclosed in embodiment 1 in CN111215084A, and methanol is generated by introducing the volume space velocity of the catalyst into a fixed bed reactor, radially flowing through a first section of catalyst bed layer 21 to perform a hydrogenation reaction at the temperature of 400 ℃ and the absolute pressure of 3 MPa;
(2) toluene is added through a liquid inlet 40 for 5h-1The mass space velocity of the catalyst is introduced into a fixed bed reactor, and the mass space velocity of the catalyst and the methanol obtained in the step (1) radially flow through a 2 nd catalyst bed layer 22 and a 3 rd section catalyst bed layer 23 to carry out alkylation reaction with the temperature of 400 ℃ and the absolute pressure of 3MPa, wherein the catalyst adopted in the alkylation reaction is the catalyst disclosed in embodiment 1 in CN101829594A, and the paraxylene is generated.
Wherein, the temperature of the hydrogenation reaction in the step (1) and the alkylation reaction in the step (2) is set by a mode of preheating the raw materials.
Application example 2
The application example uses the fixed bed reactor provided in example 2 to prepare paraxylene, and the preparation method comprises the following steps:
(1) the mixed gas of carbon dioxide and hydrogen is mixed for 1000h through an air inlet 30 according to the molar ratio of 1:2-1The catalyst is the catalyst disclosed in embodiment 1 in CN111215084A, and methanol is generated by introducing the volume space velocity of the catalyst into a fixed bed reactor, radially flowing through a first section catalyst bed layer 21 to perform a hydrogenation reaction at the temperature of 300 ℃ and the absolute pressure of 5 MPa;
(2) toluene was added through inlet 40 for 0.5h-1The mass space velocity of the catalyst is introduced into a fixed bed reactor, and the mass space velocity of the catalyst and the methanol obtained in the step (1) radially flow through a 2 nd catalyst bed layer 22 and a 3 rd catalyst bed layer 23 to carry out alkylation reaction with the temperature of 300 ℃ and the absolute pressure of 5MPa, wherein the catalyst adopted in the alkylation reaction is the catalyst disclosed in embodiment 1 in CN101829594A, and the paraxylene is generated.
Wherein, the temperature of the hydrogenation reaction in the step (1) and the alkylation reaction in the step (2) is set by a mode of preheating the raw materials.
Application example 3
The application example uses the fixed bed reactor provided in example 3 to prepare paraxylene, and the preparation method comprises the following steps:
(1) the mixed gas of carbon dioxide and hydrogen is mixed for 12000h through an air inlet 30 according to the molar ratio of 1:10-1The catalyst is a catalyst disclosed in embodiment 1 in CN111215084A, and methanol is generated by introducing the catalyst into a fixed bed reactor, radially flowing through a first section catalyst bed layer 21 to perform a hydrogenation reaction at the temperature of 450 ℃ and the absolute pressure of 0.3 MPa;
(2) toluene was added through inlet 40 for 10h-1The mass space velocity of the catalyst is introduced into a fixed bed reactor, and the mass space velocity of the catalyst and the methanol obtained in the step (1) radially flow through a 2 nd catalyst bed layer 22 and a 3 rd section catalyst bed layer 23 to carry out alkylation reaction with the temperature of 450 ℃ and the absolute pressure of 0.3MPa, wherein the catalyst adopted in the alkylation reaction is the catalyst disclosed in embodiment 1 in CN101829594A, and the paraxylene is generated.
Wherein, the temperature of the hydrogenation reaction in the step (1) and the alkylation reaction in the step (2) is set by a mode of preheating the raw materials.
Application example 4
In the present application example, the fixed bed reactor provided in application example 4 is used to prepare paraxylene, and the specific preparation method is the same as that in application example 1, and therefore, details are not described herein.
Application example 5
In the present application example, the fixed bed reactor provided in example 5 is used to prepare paraxylene, and the specific preparation method is the same as that in application example 1, and therefore, details are not described herein.
Application example 6
The application example uses the fixed bed reactor provided in example 6 to prepare paraxylene, and the preparation method comprises the following steps:
(1) the mixed gas of carbon dioxide and hydrogen is mixed for 6000h through the gas inlet 30 according to the molar ratio of 1:6-1The volume space velocity of the catalyst is introduced into a fixed bed reactor, the catalyst radially flows through a first section 1 of catalyst bed layer 21 and the temperature is 400 ℃,the absolute pressure of the hydrogenation reaction is 3MPa, and the catalyst adopted in the hydrogenation reaction is the catalyst disclosed in CN111215084A in example 1, so that methanol is generated;
(2) toluene was added through inlet 40 for 5h-1The mass space velocity of the catalyst (2) is introduced into a fixed bed reactor, and the mass space velocity of the catalyst (2) and the methanol obtained in the step (1) radially flow through a second catalyst bed layer 22 to carry out an alkylation reaction with the temperature of 400 ℃ and the absolute pressure of 3MPa, wherein the catalyst adopted in the alkylation reaction is the catalyst disclosed in embodiment 1 of CN101829594A, and the paraxylene is generated.
Wherein, the temperature of the hydrogenation reaction in the step (1) and the alkylation reaction in the step (2) is set and maintained by winding a heating belt on the surface of the reactor.
Comparative application example 1
The comparative application example uses the fixed bed reactor provided in comparative example 1 to prepare paraxylene, and the preparation method specifically comprises the following steps: the mixed gas of carbon dioxide and hydrogen is mixed for 6000h through the gas inlet 30 according to the molar ratio of 1:6-1Is introduced into the fixed bed reactor, and toluene is introduced through the liquid inlet 40 for 5h-1The mixed carbon dioxide, hydrogen and toluene radially flow through a catalyst bed layer 20 to carry out a hydrogenation coupling alkylation reaction at the temperature of 400 ℃ and the absolute pressure of 3MPa, and the catalyst adopted in the hydrogenation coupling alkylation reaction is the catalyst disclosed in embodiment 1 in CN 110743609A to generate paraxylene.
Wherein the temperature of the hydrogenation coupling alkylation reaction is set by means of preheating the raw material.
Comparative application example 2
The comparative application example applied the fixed bed reactor provided in comparative example 2 to prepare paraxylene, and the preparation method included the following steps:
(1) the mixed gas of carbon dioxide and hydrogen is mixed for 6000h through the gas inlet 30 according to the molar ratio of 1:6-1The catalyst is CN111215084A, example 1 in the fixed bed reactor, axially flows through the first section catalyst bed layer 21 to carry out the hydrogenation reaction with the temperature of 400 ℃ and the absolute pressure of 3MPa, and the catalyst adopted by the hydrogenation reaction is CN111215084AOpening the catalyst to generate methanol;
(2) toluene was added through inlet 40 for 5h-1The mass space velocity of the catalyst is introduced into a fixed bed reactor, and the mass space velocity of the catalyst and the methanol obtained in the step (1) axially flow through a 2 nd catalyst bed layer 22 and a 3 rd catalyst bed layer 23 to carry out an alkylation reaction with the temperature of 400 ℃ and the absolute pressure of 3MPa, wherein the catalyst adopted in the alkylation reaction is the catalyst disclosed in embodiment 1 in CN101829594A, and the paraxylene is generated.
Wherein, the temperature of the hydrogenation reaction in the step (1) and the alkylation reaction in the step (2) is set by a mode of preheating the raw materials.
The results of the carbon dioxide conversion and p-xylene selectivity tests of application examples 1-6 and comparative application examples 1-2 are shown in Table 1.
TABLE 1
| CO2Conversion (%) | P-xylene selectivity (%) | |
| Application example 1 | 32 | 98 |
| Application example 2 | 30 | 95 |
| Application example 3 | 25 | 88 |
| |
23 | 87 |
| Application example 5 | 33 | 98 |
| Application example 6 | 22 | 86 |
| Comparative application example 1 | 20 | 85 |
| Comparative application example 2 | 16 | 80 |
As can be seen from Table 1: application examples 1-6 all significantly improved CO over comparative application examples 1-22Conversion and para-xylene selectivity, and comparison between comparative application example 1 and application example 1 shows that the multi-stage catalyst bed is superior to the single-stage catalyst bed, and comparison between comparative application example 2 and application example 1 shows that radial flow of the gas phase through the catalyst bed is superior to axial flow through the catalyst bed.
Therefore, the fixed bed reactor provided by the utility model has the advantages that the axial gas guide pipe is arranged in the center of the multi-section catalyst bed layer, and the gas outlet holes are uniformly distributed on the side wall of the axial gas guide pipe, so that the radial flow of reaction materials in the catalyst bed layer is realized, the reaction process is strengthened, the fixed bed reactor is suitable for high-airspeed operation, the conversion rate of raw materials is improved, and the selectivity of byproducts is reduced. In addition, the fixed bed reactor provided by the utility model realizes multi-step feeding operation by arranging a plurality of liquid inlets on the side wall of the reactor shell, and combines reasonable control of materials and the temperature of the reactor, so that the reaction can be carried out under the optimal dynamic condition close to thermodynamic equilibrium, and the conversion rate of raw materials and the selectivity of target products are further improved.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. The axial-radial flow multi-step feeding fixed bed reactor is characterized by comprising a shell and at least 2 sections of catalyst bed layers arranged in the shell;
the shell comprises at least 1 air inlet, 2-8 liquid inlets and at least 1 product outlet;
the liquid inlet is positioned on the side wall of the shell between every 2 sections of catalyst bed layers;
an axial gas guide pipe is arranged in the center of the catalyst bed layer;
the tail end of the axial air duct is closed, and air outlet holes are uniformly distributed in the side wall of the axial air duct.
2. The fixed bed reactor of claim 1, wherein a gas conducting zone is further disposed between the sidewall of the catalyst bed and the shell;
the top and the bottom of the catalyst bed layer are both closed;
the top of the air guide area is closed, and the bottom of the air guide area is opened.
3. The fixed bed reactor of claim 1, wherein the number of gas inlets is 1, and the gas inlets are disposed at the top of the housing;
the product outlet is 1 and is arranged at the bottom of the shell.
4. The fixed bed reactor of claim 1, wherein the liquid inlet is further connected with an atomizing nozzle, and the outlet of the atomizing nozzle is opposite to the flowing direction of the gas phase in the reactor.
5. The fixed bed reactor of claim 1, wherein the cross-section of the shell is circular with a diameter of 0.5-2 m;
the height of the shell is 6-20 m.
6. The fixed bed reactor of claim 1, wherein the axial gas-guide tubes have a cross-sectional diameter of 0.1 to 0.4m and a sidewall opening ratio of 5% to 20%.
7. The fixed bed reactor of claim 1, wherein the gas outlet has a pore size of 2-16 mm.
8. The fixed bed reactor as set forth in claim 1 wherein the spacing between each 2-stage catalyst bed is 400-800 mm.
9. The fixed bed reactor of claim 1 wherein the height of the 1 st stage catalyst bed, as counted from the top of the shell, is from 1.5 to 3 times the height of the remaining catalyst beds.
10. The fixed bed reactor of claim 1, wherein the axial gas-conducting tubes extend out of the catalyst bed at the center of the 1 st stage catalyst bed from the top of the housing and are connected to the gas inlet.
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