CN100415356C - A gas-solid phase reaction device suitable for highly heat-sensitive substances - Google Patents

Abstract

The present invention relates to a gas and solid phase reaction device of high heat sensitive substances, which mainly comprises three chemical industry unit equipment of a raw material flow heat booster, a catalytic reactor of a fixed bed and a product material flow condenser. The device can greatly improve the yield of heat sensitive substances by an improved catalytic reactor of a fixed bed-a tube array type multisection catalytic reactor with short bed layers, and greatly improve the service life of catalysts and the productivity of a device.

Description

A gas-solid phase reaction device suitable for highly heat-sensitive substances

technical field

The invention relates to a gas-solid phase catalytic reaction device, in particular to a gas-solid phase catalytic reaction device suitable for highly heat-sensitive substances.

Background technique

As we all know, the general gas-solid phase catalytic reaction system, the reaction device mainly includes raw material preheater, fixed bed reactor with catalyst, and unit equipment such as condenser, and its technology is relatively mature. However, for heat-sensitive substances, especially the reaction system of certain high-heat-sensitive substances with large heat release, in the existing fixed-bed reactors equipped with catalysts, these highly heat-sensitive substances are prone to decomposition and polymerization due to excessive temperature. , coking and other phenomena, resulting in the low yield of the target product and the rapid deactivation of the catalyst and other worsening conditions, so that the catalytic reaction process is forced to stop, such as isobutyraldehyde gas-solid phase catalytic reaction to synthesize diacetyl, due to its The main reaction is a relatively complex molecular rearrangement and oxidation reaction. Not only the initial temperature required for the main reaction is relatively high, but also the contact time between the reaction gas and the catalyst is required to be moderate. At the same time, other side reactions with large heat release , so it is very difficult to moderately control the reaction temperature, and the existing tube-and-tube gas-solid-phase catalytic reaction device for heat-sensitive substances is not suitable for the gas-solid-phase catalytic reaction of highly heat-sensitive substances, because when the catalytic reaction is carried out by these devices, it is still very difficult. It is prone to temperature runaway phenomenon, that is, the hot spot temperature is too high or the phenomenon of flying temperature is said in the industry. This is because the generated product diacetyl itself has extremely strong heat sensitivity, and its high-temperature heating time should not be too long, and the existing catalyst is a porous material, which is not easy to dissipate heat, so the diacetyl produced by the reaction is It is easy to cause excessive oxidation, decomposition, condensation and polymerization in the catalyst bed due to high temperature overheating, and high temperature carbon precipitation and coking will occur, which not only leads to a significant decrease in the yield of diacetyl, but also easily deactivates the catalyst rapidly, affecting normal operation of production.

German patent DE 78-285716 discloses a method for synthesizing diacetyl by gas-solid phase catalytic reaction of isobutyraldehyde. The catalyst contains active components such as manganese oxide, zinc oxide or titanium oxide, and the highest selectivity of the target product is 11.2%. , the conversion rate of isobutyraldehyde is 87%, which shows that most of the raw material isobutyraldehyde has become waste, and also shows that the catalytic synthesis of highly heat-sensitive substances does have quite high technical difficulty.

In addition, we can analyze from the perspective that the market price ratio between diacetyl and isobutyraldehyde is as much as 20 times, and we can also prove from another side: "The technical difficulty of catalytic synthesis of highly heat-sensitive substances".

For this reason, the industrial sector urgently hopes that relevant technical workers can innovate and provide a device suitable for the catalytic production of highly heat-sensitive substances, as well as a special catalyst with excellent performance.

Contents of the invention

Purpose of the present invention:

In order to overcome the above-mentioned shortcomings of the prior art, a gas-solid phase catalytic reaction device suitable for the synthesis of diacetyl, a highly heat-sensitive substance, is provided, mainly to meet the requirements of the industrial sector from the perspective of improving the catalytic production device, so as to promote the catalysis of highly heat-sensitive substances. Technological progress in production (relevant special catalysts with excellent performance will be protected by another patent application).

Design of the present invention is such:

In the face of the special situation that the catalytic reaction of highly heat-sensitive substances is different from that of general heat-sensitive substances, we first conducted a large number of experiments and found that:

(1) The reason why the existing multi-tubular fixed-bed catalytic reaction device is not suitable for the catalytic production of highly heat-sensitive substances is that its fundamental reason is that the catalytic bed of the reaction device provided by the prior art is too long, and the length of the general catalytic reaction tube is long Not only the catalytic reaction process is continuous, but also the activity of the catalyst filled in the catalytic bed is continuously increasing along the axial direction as the reaction progresses. Excessive catalysis seriously affects the catalytic production of highly heat-sensitive substances.

(2) Catalytic reaction process For highly heat-sensitive substances, it is more important to remove excess heat of reaction in a timely manner and prevent side reactions caused by overheating than ordinary heat-sensitive substances. Therefore, how to make the catalytic reaction in the "hot spot" Stopping before it occurs is an important content that must be considered in improving catalytic reactors.

(3) For the catalytic reaction production of highly heat-sensitive substances, how to adjust the activity of the catalyst bed and arrange the catalyst bed reasonably is also an important issue. The purpose of adjusting catalyst activity is to maintain and further expand the results of catalytic reactions.

Accordingly, the present invention conceives a gas-solid phase reaction device suitable for synthesizing high heat-sensitive substance diacetyl, which mainly includes a raw material stream preheater, a fixed-bed reactor equipped with a catalyst, and a product stream condenser. The unit equipment is connected by pipelines. The fixed-bed reactor is a tubular short-bed multi-stage catalytic reactor. The catalytic reaction can greatly improve the yield of the target product and the service life of the catalyst to meet the urgent needs of the industrial sector.

According to above-mentioned design the present invention also is realized like this:

In view of the fact that highly heat-sensitive substances have a strong exothermic effect in certain gas-solid phase reactions such as oxidation reactions, and the reaction products are very sensitive to high temperatures in the catalyst layer, so it is first necessary to consider how to effectively eliminate the accumulation of reaction heat in the catalyst bed , to remove excess heat of reaction in time to prevent the generation of hot spots, and to maintain the reaction temperature of the catalyst bed within the normal range; residence time in the catalyst layer. By shortening the continuous contact time between the reaction gas and the catalyst bed, especially using the "wall effect" of the gas flow when the height of the catalyst layer is not greater than 20 times the pipe diameter, the oxidation reaction can reach a higher temperature or far before the temperature is out of control. Just make it out of contact with the catalyst, stop the reaction timely and effectively, and leave a certain space at the same time to eliminate the radial temperature gradient and concentration gradient in the reaction tube, and pass the heat carrier between the tubes of the fixed bed reactor To remove most of the heat, reduce the temperature of the reaction gas, and then further react in the subsequent catalyst layer, and by gradually reducing the height of the catalyst layer, shorten the residence time of the heat-sensitive substance with increased concentration in the catalyst layer, in addition , set multiple heat carrier inlets near the outlet of the reaction gas to eliminate the heat transfer dead angle where the concentration of the heat-sensitive material is high, and further improve the conversion rate and yield of the target product of the heat-sensitive material, thereby achieving a more significant effect .

In this device of the present invention, at least comprise three chemical unit equipments of raw material stream preheater, fixed-bed reactor that catalyst is housed, product stream condenser;

Said fixed-bed reactor is a tubular short-bed multi-stage catalytic reactor (hereinafter referred to as fixed-bed reactor), the inside of the reaction tube is a gas phase channel, and the space between the reaction tubes is a heat carrier. aisle;

In each reaction tube of the fixed-bed reactor, there are one or more components or combination components that allow the reaction gas to pass through and redistribute the reaction gas evenly and reduce the temperature, so that the catalyst bed in the reaction tube is axially divided into There are two or more sections with a certain distance, and at the same time, the height of at least one section of the catalyst bed is not greater than 20 times the inner diameter of the reaction tube. The reaction becomes gap-catalyzed so that excess heat of reaction is further removed within the component or composite component segment.

The fixed bed reactor is provided with at least two heat carrier inlets and is close to the reaction gas outlet of the fixed bed reactor, and at least two heat carrier outlets are arranged near the reaction gas inlet of the fixed bed reactor.

Said components or combined components are orifice plates or silk screens, or their assemblies, or their assemblies with supports.

Said components or combined components are made of metal materials with better thermal conductivity, which can not only further remove excess heat of reaction in the reaction gas, but also redistribute the reaction gas uniformly in the radial direction.

The component or composite component arranged in the reaction tube separates the front and rear catalysts from 0.2 to 2.0 times the height of the front catalyst.

The component or composite component arranged in the reaction tube separates the front and rear catalyst stages from 0.5 to 1.5 times the height of the front stage catalyst.

The height of the catalyst bed in the section of the reaction tube closest to the reaction gas inlet end is not greater than 20 times the inner diameter of the reaction tube;

The height of each section of the catalyst bed in the reaction tube is not greater than 20 times the inner diameter of the reaction tube;

The height of the catalyst bed in the reaction tube that is farther away from the reaction gas inlet is less than the height of the catalyst bed that is closer to the reaction gas inlet, and is less than or equal to the height of the catalyst bed that is closer to the reaction gas inlet. 70% of the height of the catalyst bed at this section is preferably.

The average equivalent diameter of the catalyst particles in the section of the catalyst bed farther away from the reaction gas inlet in the reaction tube is greater than the average equivalent diameter of the catalyst particles in the section of the catalyst bed closer to the reaction gas inlet.

The catalyst activity of the catalyst in the section of the catalyst bed farther from the reaction gas inlet in the reaction tube is smaller than the activity of the catalyst in the section of the catalyst bed closer to the reaction gas inlet.

The device of the present invention operates like this: after the reaction raw material is gasified in the raw material flow preheater and mixed with oxygen or gas containing oxygen, it passes through the fixed bed reactor equipped with catalyst in a gaseous state, and simultaneously between the reactor tubes The heat carrier is introduced to control the axial temperature of the reactor, and the excess heat of reaction generated in the catalytic reaction process is removed in time, and then the product stream includes the target product, by-products and unreacted raw materials in the product stream through the product stream condenser. The internal stream is condensed, and then the target product is obtained by conventional refining methods.

The device of the present invention can effectively control the reaction temperature of highly heat-sensitive substances in certain gas-solid phase exothermic reactions such as oxidation reactions, relieve excessive oxidation, decomposition, polymerization, condensation, coking, and carbon precipitation, etc., and can not only significantly improve The selectivity and yield of the target product can be improved, and the continuous operation period of the catalyst bed and the service life of the catalyst can be extended. Further illustrate the content of the present invention below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is a structural schematic diagram of the device unit equipment combination process and the fixed bed reactor of the present invention.

in:

1——Raw material stream preheater;

2—component or combined component;

3——reaction tube (the number depends on the production scale);

4——Heating medium outlet, which is close to the reaction gas inlet end of the fixed bed reactor;

5—catalyst bed;

6——Fixed-bed reactor with catalyst;

7 - heat carrier inlet, which is close to the reaction gas outlet end of the fixed bed reactor;

8—product stream condenser.

As can be seen from Fig. 1, device of the present invention at least comprises raw material stream preheater (1), fixed-bed reactor (6) that catalyzer is housed, product stream condenser (8);

Said fixed-bed reactor (6) is a kind of short-bed multi-stage catalytic reactor by shell and tube type, and the pipe of its reaction tube (3) is a gas phase channel, and the tubes of its reaction tube (3) are heat-carrying Body channel;

In the reaction tube (3) of the fixed-bed reactor (6), one or more members or combination members (2) that allow gas to pass through and redistribute the reaction gas evenly are provided, and the reaction tube (3) The catalyst bed (5) in ) is divided into two or more sections with a certain distance along the axial direction, and at the same time, the height of at least one of the catalyst beds is not greater than 20 times the inner diameter of the reaction tube (3);

The fixed bed reactor (6) is provided with at least two heat carrier inlets (7) and is close to the reaction gas outlet end of the fixed bed reactor (6), and is provided with at least two heat carrier outlets (4) and is close to the fixed bed The reaction gas inlet end of the reactor (6).

Said component or combined component (2) is an orifice plate or a silk screen, or their assembly, or their supported assembly.

Said components or combined components (2) are made of metal materials with better thermal conductivity.

The component or combined component (2) arranged in the reaction tube (3) separates the front and rear catalysts from 0.2 to 2.0 times of the loading height of the former catalyst.

The component or combined component (2) arranged in the reaction tube (3) separates the front and rear catalysts from 0.5 to 1.5 times the height of the front catalyst.

The height of the catalyst bed at the nearest part of the reaction tube (3) from the reaction gas inlet end is not greater than 20 times the inner diameter of the reaction tube (3);

The height of each section of the catalyst bed in the reaction tube (3) is not greater than 20 times of the internal diameter of the reaction tube (3);

The height of the catalyst bed in the section of the reaction tube (3) farther away from the reaction gas inlet is smaller than the height of the catalyst bed in the section closer to the reaction gas inlet.

The height of the catalyst bed in the section of the reaction tube (3) that is far away from the reaction gas inlet is less than or equal to 70% of the height of the catalyst bed in the section that is closer to the reaction gas inlet.

The average equivalent diameter of the catalyst particles in the catalyst bed in the reaction tube (3) that is farther away from the reaction gas inlet is larger than the average equivalent diameter of the catalyst particles in the catalyst bed that is closer to the reaction gas inlet.

The catalyst activity of the catalyst bed in the section of the reaction tube (3) farther from the reaction gas inlet end is smaller than the catalyst activity of the catalyst bed in the section closer to the reaction gas inlet end.

The content of the present invention will be further clarified below in conjunction with examples, but these examples do not limit the scope of application of the present invention.

Detailed ways

Example 1

In a tubular short-bed multi-stage catalytic reactor (referred to as a fixed-bed reactor), the inner diameter of the reaction tube is 25mm, filled with active components such as oxides of manganese, zinc, and copper provided by the Shanghai Industrial Technology Research Institute. The reaction tube is equipped with a combined member with a height of 150mm composed of wire mesh and porous metal plate, which divides the catalyst filling area into two sections of 100mm and 50mm, and the front and rear sections are also filled with an average equivalent diameter of φ1.5 For the amorphous catalyst, heat transfer oil with an inlet temperature of about 260-280°C is used to enter from the lower part of the fixed-bed reactor in three ways, and flow out from the upper part of the fixed-bed reactor in three ways, and the catalyst in the fixed-bed reactor After the bed temperature rises to the predetermined temperature, the raw material flow preheater is turned on, the main raw material isobutyraldehyde is vaporized and mixed with the gas containing oxygen, and then passed into the fixed bed reactor for reaction, and finally the reaction gas is passed through A product stream condenser collects a product stream containing diacetyl. The reaction yield of diacetyl reaches the highest when the space velocity of the reactant flow is 2000h ^-1 ~ 5200h ^-1 , and the reaction yield of the target product after tuning is basically stable at about 24%, and the selectivity is maintained at about 32%. No obvious inactivation has been seen after using for more than 100 hours.

Example 2

In a tubular short-bed multi-stage catalytic reactor (referred to as a fixed-bed reactor), the inner diameter of the reaction tube is 25mm, filled with active components such as oxides of manganese, zinc, and copper provided by the Shanghai Industrial Technology Research Institute. The reaction tube is equipped with a combined member with a height of 60mm composed of wire mesh and porous metal plate, which divides the catalyst filling area into two sections of 300mm and 200mm, and the average equivalent diameter of the front and rear sections is φ1.5 and the amorphous catalyst of φ2.25, use heat transfer oil with an inlet temperature of about 260-280°C, enter from the lower part of the fixed bed reactor in three ways, and flow out from the upper part of the fixed bed reactor in three ways, and the fixed bed After the temperature of the catalyst bed in the reactor reaches the predetermined temperature, the raw material flow preheater is turned on, the main raw material isobutyraldehyde is vaporized and mixed with the gas containing oxygen, and then passed into the fixed bed reactor for reaction, and finally The reaction gas is passed through a product stream condenser to collect a product stream containing diacetyl. The reaction yield of diacetyl reaches the highest when the space velocity of the reactant flow is 3500h ^-1 ~ 5200h ^-1 , and the reaction yield of the target product after tuning is basically stable at about 22%, and the selectivity is maintained at about 28%. No obvious inactivation has been seen after using for more than 100 hours.

Example 3

In a tubular short-bed multi-stage catalytic reactor (referred to as a fixed-bed reactor), the inner diameter of the reaction tube is 25mm, filled with active components such as oxides of manganese, zinc, and copper provided by the Shanghai Industrial Technology Research Institute. The reaction tube is equipped with a combined member with a height of 200mm composed of wire mesh and metal support packing, which divides the catalyst filling area into two sections of 100mm and 70mm, and the average equivalent diameter of the front and rear sections is φ1.5 The amorphous catalyst and the φ2.25 columnar catalyst use heat transfer oil with an inlet temperature of about 260-280°C, enter from the lower part of the fixed-bed reactor in three ways, and flow out from the upper part of the fixed-bed reactor in three ways After the temperature of the catalyst bed in the fixed-bed reactor reaches the predetermined temperature, the raw material stream preheater is turned on, the main raw material isobutyraldehyde is vaporized and mixed with oxygen-containing gas, and then passed into the fixed-bed reactor The reaction is carried out, and finally the reaction gas is passed through the product stream condenser to collect the product stream containing diacetyl. The reaction yield of diacetyl reaches the highest when the space velocity of the reactant flow is 2600h ^-1 ~ 5200h ^-1 , and the reaction yield of the target product after tuning is basically stable at about 22%, and the selectivity is maintained at about 30%. No obvious inactivation has been seen after using for more than 100 hours.

Example 4

In a tubular short-bed multi-stage catalytic reactor (referred to as a fixed-bed reactor), the inner diameter of the reaction tube is 25mm, filled with active components such as oxides of manganese, zinc, and copper provided by the Shanghai Industrial Technology Research Institute. The reaction tube is equipped with combined components with a height of 150mm and 100mm, which are composed of wire mesh. The catalyst bed is divided into three sections of 300mm, 200mm and 100mm, and the catalyst filling areas of the front and back three sections are filled with pellets. Spherical catalysts with a diameter of 0.9mm, 1.5mm and 2.5mm, use heat transfer oil with an inlet temperature of about 260-280°C, enter from the lower part of the fixed-bed reactor in three ways, and enter from the upper part of the fixed-bed reactor in three ways After the temperature of the catalyst bed in the fixed-bed reactor is raised to a predetermined temperature, the raw material flow preheater is turned on, and the main raw material isobutyraldehyde is vaporized and mixed with oxygen-containing gas, and then passed into the fixed-bed reactor The reaction is carried out, and finally the reaction gas is passed through the product stream condenser to collect the product stream containing the target product diacetyl. The reaction yield of diacetyl reaches the highest when the space velocity of the reactant flow is 2000h ^-1 ~5200h ^-1 , and the reaction yield of the target product diacetyl is basically stable at about 24% after optimization, and the selectivity can be maintained at 28 In the range of ~32%, the catalyst has not been significantly deactivated after being used for more than 100 hours.

Comparative example 1

In the said fixed bed reactor of the present invention, the inner diameter of the reaction tube is 25mm, and the amorphous catalyst with higher activity and the cylindrical catalyst with lower activity of 400mm to 600mm are packed separately or in continuous layered combination respectively. Heat conduction oil with a temperature of about 260-280°C. After raising the temperature of the catalyst bed in the fixed-bed reactor to the predetermined temperature, the raw material flow preheater is turned on to vaporize the main raw material isobutyraldehyde and mix it with the gas containing oxygen. Afterwards, it is passed into a fixed-bed reactor for reaction, and finally the reaction gas is passed through a condenser to collect the product stream containing the diacetyl target product. Under multiple optimized operating conditions, the reaction yield of diacetyl can reach the highest when the space velocity of the reactant stream is 2600h ^-1 , and when the space velocity changes more than about 20%, the yield drops sharply, but even at the space velocity of 2600h When ^-1 , the highest yield can only reach 16%, and the selectivity is only 24%. After 8 to 48 hours of use, the catalyst will gradually show obvious deactivation phenomenon. The loading method and effect are shown in the table below.

serial number Catalyst loading method Maximum yield, % selectivity, % Optimum airspeed, h^-1 Catalyst deactivation time, h 1 400mmφ1.5 Amorphous 13 twenty two 2600 ~24 2 400mmφ1.5 Cylindrical 13 20 2600 ~48 3 300mmφ1.5 cylindrical + 200mmφ1.5 amorphous 12 18 2600 ~8 4 300mmφ1.5 amorphous + 200mmφ1.5 cylindrical 15 twenty three 2600～3500 ~36 5 300mmφ1.5 amorphous + 200mmφ1.5 cylindrical + 100mmφ2.5 cylindrical 16 twenty four 2600～3500 ~36

Visible by embodiment 1～4 and comparative example 1:

Even in the same tube-and-tube short-bed multi-stage catalytic reactor, from the perspective of setting components and not setting components:

(1) The yield of the target product has obvious difference. The reactor with components is arranged, and the yield of its target product is improved by at least 6 percentage points than the reactor without components, and the increase reaches about 38%. If it is compared with the prior art Ratio, then the increase of its yield exceeds 100%.

(2) The space velocity of the reactant flow can be doubled at most, and the yield of the target product can be kept stable within a large elastic range of operation.

(3) The service life of the catalyst is greatly improved, and the regeneration period of the catalyst can be increased several times at least.

In addition, if the device of the present invention is used in the synthesis of diacetyl by gas-solid phase oxidation of butanone and the synthesis of acetoin by gas-solid phase catalysis of 2,3-butanediol, good results can also be obtained.

In a word, due to the technical progress of the present invention, the requirements of industrial sectors for the catalytic production of highly heat-sensitive substances can be met.

Claims (7)

1. A gas-solid phase reaction device suitable for synthesizing highly heat-sensitive material diacetyl, in the device, at least comprising a raw material flow preheater (1), a fixed-bed reactor (6) with a catalyst and a product flow Condenser (8), said fixed-bed reactor (6) wherein, is a kind of shell-and-tube type short-bed multistage catalytic reactor, is the gas phase passage in the tube of its reaction tube (3), and its reaction tube (3) Between the tubes is the heat carrier passage; the fixed bed reactor (6) is provided with at least two heat carrier inlets and is close to the reaction gas outlet end of the fixed bed reactor (6), and is provided with at least two heat carrier outlets and Near the reaction gas inlet end of fixed-bed reactor (6); It is characterized in that: In the reaction tube (3) of the fixed bed reactor (6), one or more members that allow gas to pass through and reactant gas to be evenly distributed are set, and the catalyst bed in the reaction tube (3) ( 5) It is divided into multiple sections with a certain distance along the axial direction, and at the same time, the height of at least one section of the catalyst bed is not greater than 20 times the inner diameter of the reaction tube (3); the reaction tube (3) is farther away from the reaction gas inlet end The height of that section of the catalyst bed is less than the height of the section of the catalyst bed that is closer to the reaction gas inlet end; The equivalent diameter is greater than the average equivalent diameter of the catalyst particles in the catalyst bed near the reaction gas inlet; and the said component is made of metal material with better thermal conductivity. 2. The reaction device according to claim 1, characterized in that: said member is an orifice plate or a wire mesh, or their assembly, or their supported assembly. 3. The reaction device according to claim 1 or 2, characterized in that: the member provided in the reaction tube (3) separates the space between the front and rear catalysts, which is 0.2-20% of the filling height of the front catalyst. 2.0 times. 4. The reaction device according to claim 1 or 2, characterized in that: the member provided in the reaction tube (3) separates the space between the front and rear catalysts, which is 0.5-5% of the filling height of the front catalyst. 1.5 times. 5. reaction device according to claim 1, is characterized in that: the height of this section of catalyst bed in reaction tube (3) apart from reaction gas inlet end nearest place, is not greater than 20 times of reaction tube (3) inner diameter. 6. The reaction device according to claim 1 or 5, characterized in that: the height of each section of the catalyst bed in the reaction tube (3) is not greater than 20 times of the inner diameter of the reaction tube (3). 7. The reaction device according to claim 1 or 5, characterized in that: the height of the catalyst bed in the reaction tube (3) that is far away from the reaction gas inlet end is less than or equal to the distance from the reaction gas inlet end. The height of the near catalyst bed is 70%.

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