CN119909600A - Reactor for producing hydrogen by catalytic cracking of methane and method for producing hydrogen by catalytic cracking of methane - Google Patents

Abstract

The invention provides a reactor for producing hydrogen by methane catalytic pyrolysis, which comprises a tube, an upper end socket connected to the upper end of the tube and a lower end socket connected to the lower end of the tube, a catalyst basket arranged in the tube, support tubes with two open ends, a thermowell penetrating through the support tubes, wherein the upper open ends of the support tubes are connected to the bottom of the catalyst basket, the lower open ends of the support tubes are abutted against the top of the lower end socket, and the upper ends of the thermowell extend into the catalyst basket along with the upper open ends of the support tubes, and the lower ends of the thermowell extend out of the lower end socket. The reactor can facilitate the filling of the catalyst and is simple to operate, so that the catalytic reaction evaluation of the hydrogen production by methane catalytic cracking is accurate, quick and efficient.

Description

Reactor for producing hydrogen by methane catalytic pyrolysis and method for producing hydrogen by methane catalytic pyrolysis

Technical Field

The invention relates to the technical field of hydrogen preparation, in particular to a reactor for producing hydrogen by methane catalytic pyrolysis and a method for producing hydrogen by methane catalytic pyrolysis.

Background

Hydrogen is an important fuel and industrial raw material, the traditional hydrogen production method mainly uses water electrolysis and high-temperature and high-pressure steam conversion of hydrocarbons such as methane, wherein the methane steam reforming process is mature in industrial application, but the traditional hydrogen production process has the defects of high energy consumption, high cost, large investment and the like, in recent years, new technology for producing hydrogen by methane catalytic cracking is developed, and hydrogen and carbon nano tubes without carbide can be prepared by cracking methane.

The method is characterized in that a high-efficiency catalyst is selected by methane catalytic pyrolysis hydrogen production, the quality and effect of the catalyst are measured, three comprehensive indexes such as activity, selectivity and service life of the catalyst are mainly examined, the performance of the catalyst is generally evaluated and analyzed by adopting a fixed bed reactor at present, but due to various limitations of conventional catalyst evaluation devices in laboratories, the conventional catalyst evaluation devices basically adopt a quartz tube or stainless steel tube seat fixed bed reactor, and the defects of high fluid flow resistance, poor heat transfer, difficult temperature control and the like are generally caused.

Chinese patent CN215974954U discloses a reactor for producing hydrogen by high-temperature cracking methane with liquid metal having catalytic function, methane gas is subjected to low-temperature catalytic dehydrogenation under the action of catalyst, C _XH_Y enters into the reactor for producing hydrogen, and is cracked into hydrogen, air entering into the reactor through a vacuum pump is pumped into vacuum, so that the production of CO ₂ is reduced, the hydrogen production efficiency is improved, however, the reactor for producing hydrogen has complex structure and complex test operation. Chinese patent CN105013506a discloses a bifunctional catalyst for catalytic cracking of methane, a method for preparing the same and a method for preparing hydrogen, and proposes that the catalyst can be used for catalyzing methane to prepare hydrogen at a lower temperature and selectively oxidizing carbon deposit into CO, and the method adopts a circulating fluidized bed reactor and a regenerator to perform catalytic cracking on feed gas comprising methane to produce hydrogen and recycle the catalyst, however, the patent adopts a plurality of devices, resulting in excessively complex operation. In conclusion, the traditional catalytic evaluation method is labor-consuming and low in efficiency, and the obtained experimental data are not accurate enough.

In summary, the existing catalyst evaluation method has the problems of complex experiment, larger error, labor consumption, lower efficiency and the like.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the reactor for producing hydrogen by methane catalytic cracking and the method for producing hydrogen by methane catalytic cracking, and the reactor can be convenient for filling the catalyst and is simple to operate, so that the catalytic reaction evaluation of the methane catalytic cracking hydrogen production is accurate, quick and efficient.

In order to achieve the above object, the present invention provides a reactor for producing hydrogen by catalytic pyrolysis of methane, comprising:

The device comprises a pipe barrel, an upper sealing head connected to the upper end of the pipe barrel and a lower sealing head connected to the lower end of the pipe barrel;

A catalyst basket disposed within the barrel;

the support tube is of a hollow structure, the two ends of the support tube are both open ends, the upper open end of the support tube is connected to the bottom of the catalyst basket, and the lower open end of the support tube is abutted against the top of the lower seal head;

The thermowell penetrates through the supporting tube, the upper end of the thermowell stretches into the catalyst basket along with the upper opening end of the supporting tube, and the lower end of the thermowell stretches out of the lower end of the lower sealing head.

In some embodiments, a lining is arranged on the inner wall of the pipe barrel near the upper end, and the bottom of the catalyst basket is abutted against the surface of the lining to fix the catalyst basket.

In some embodiments, the catalyst basket is open, generally cylindrical, and tapered at the bottom.

In some of these embodiments, the catalyst basket bottom is provided with annular mounting slots and a cross baffle over which the mesh screen is covered.

In some embodiments, an external thread is provided at the lower end of the support tube, a compression spring and a compression nut are sleeved outside the support tube between the tube and the lower end socket, and tension is formed to make the bottom of the catalyst basket tightly prop against the tube and the inner liner, so as to fix the catalyst basket.

In some embodiments, a rectifying grid plate mounting groove for mounting a rectifying grid plate is arranged above the catalyst basket in the tube barrel, and a sealing ring is arranged in the rectifying grid plate mounting groove.

In some embodiments, the rectifying grating plate is placed on a step surface at the joint of the circular inner cavity at the upper end in the pipe barrel and the working cavity, and the inner part of the rectifying grating plate is uniformly distributed with pore passages along the axial direction of the pipe barrel.

In some embodiments, the upper end of the pipe barrel is connected with a connecting piece through a flange, and the connecting piece is connected with the upper sealing head.

In some embodiments, a reaction tube inlet is arranged above the tube, and a reaction tube outlet is arranged on the side wall above the bottom sealing head of the tube.

The invention also provides a method for producing hydrogen by methane catalytic pyrolysis, which adopts the reactor for producing hydrogen by methane catalytic pyrolysis and comprises the following steps:

S1, before a methane catalytic cracking hydrogen production experiment is carried out, an upper end socket, a flange and a rectifying grating plate of a reactor are removed, a certain amount of catalyst is weighed and placed into a catalyst basket, a stainless steel micropore square screen is required to cover a cross baffle plate at the bottom of the catalyst basket before filling, the rectifying grating plate, a connecting piece and the upper end socket at the upper end of a tube barrel of the reactor are fastened, a lower end socket is used for fastening the lower end of the tube barrel of the reactor, a thermocouple is inserted into a sleeve pipe of the reactor, the top end of the thermocouple is positioned in the catalyst basket, the reactor is selected and placed in a heating hearth, the catalyst basket is positioned in the middle of a heating section of the heating hearth, and then the experiment is started;

S2, firstly, introducing inert gas nitrogen, removing air in a tube, heating a reactor at the same time, setting the reduction temperature to be 200-500 ℃, setting the reduction pressure to be normal pressure, cutting off the nitrogen after the reduction temperature is raised to the top reduction temperature of the catalyst, introducing reducing gas hydrogen, and reducing the catalyst at a constant temperature;

s3, after the reduction is finished, closing a hydrogen valve, and under the purging of nitrogen, rapidly heating until the gas chromatograph does not detect hydrogen any more, and then introducing methane to start the reaction;

and S4, after the experiment is finished, taking out the reactor from the heating furnace, then disassembling each part of the reactor in the reverse order, taking out the catalyst sample in the catalyst basket, and weighing.

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

The reactor for producing hydrogen by methane catalytic pyrolysis provided by the invention has a simple structure and is convenient to detach, the hollow support tube is connected with the center of the bottom of the catalyst basket, the hollow support tube can be used for fixing the catalyst basket inside the reactor, the hollow support tube is connected with the thermowell, so that the internal components of the reactor can be reduced, the effective space of the reactor can be increased, the product can flow out of the reactor rapidly, the stainless steel metal screen mesh is arranged at the bottom of the catalyst basket, and the catalyst basket can effectively prevent coke particles generated in a catalyst family or enter a subsequent reaction pipeline so as to avoid blocking the reaction tube and prevent a catalyst evaluation experiment from being forced to stop.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of the catalytic cracking of methane to produce hydrogen in accordance with an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a reactor for producing hydrogen by catalytic cracking of methane according to an embodiment of the present invention;

FIG. 3 is a schematic view of the mating structure of a catalyst basket, support tube, thermowell shown in an embodiment of the present invention;

FIG. 4 is a schematic view of a mesh screen structure of a catalyst basket according to an embodiment of the present invention;

FIG. 5 is a bottom plan view of a catalyst basket according to an embodiment of the present invention;

wherein:

1-a tube barrel;

101-lining;

102-reaction tube inlet;

103-the reaction tube outlet;

2-an upper sealing head;

3-a lower end socket;

4-a catalyst basket;

401-an annular mounting groove;

402-a cross baffle;

403 mesh screen;

5-supporting the tube;

6-thermowell;

7-compressing a spring;

8-compressing the nut;

9-rectifying grating plates;

10-rectifying grid plate mounting grooves;

11-a sealing ring;

12-connecting piece;

13-flange.

Detailed Description

The following detailed description of the present invention is provided with reference to the accompanying drawings and specific embodiments, so as to further understand the purpose, the scheme and the effects of the present invention, but not to limit the scope of the appended claims.

Certain terms are used throughout the description and following claims to refer to particular components or elements, and it will be appreciated by those of ordinary skill in the art that a technical user or manufacturer may refer to the same component or element by different terms or terminology. The present specification and the following claims do not take the form of an element or component with the difference in name, but rather take the form of an element or component with the difference in function as a criterion for distinguishing. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The term "coupled," as used herein, includes any direct or indirect electrical connection. Indirect electrical connection means include connection via other devices.

It should be noted that, in the description of the present invention, terms such as "transverse," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "about," or "about," "substantially," "left and right," etc. indicate orientations or positional relationships or parameters, etc. based on the orientation or positional relationships shown in the drawings, are merely for convenience of description and simplicity of description, and do not indicate or imply that the apparatus or elements being referred to must have a specific orientation, a specific size, or be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

The invention provides a reactor for producing hydrogen by methane catalytic pyrolysis, which comprises a pipe barrel 1, an upper sealing head 2 connected to the upper end of the pipe barrel 1 and a lower sealing head 3 connected to the lower end of the pipe barrel 1, wherein the bottom of the pipe barrel 1 is in threaded connection with the lower sealing head 3, the upper sealing head 2 and the lower sealing head 3 are respectively and detachably connected with the pipe barrel 1, the pipe barrel 1 in the embodiment is a stainless steel pipe, the length is 600mm, the outer diameter of the pipe is 40mm, and the wall thickness is 4mm. The electric heating furnace comprises a tube 1, a catalyst basket 4, a support tube 5, a thermowell 6, wherein the catalyst basket 4 is arranged in the tube 1 and corresponds to the middle part of a heating section of the electric heating furnace, the support tube 5 is 330mm in length, 6mm in outer diameter and 2mm in wall thickness, the support tube 5 is of a hollow structure, two ends of the support tube 5 are open ends, the upper open end of the support tube 5 is connected with the center of the bottom of the catalyst basket 4, the lower open end of the support tube 5 is abutted against the top of the lower sealing head 3, the thermowell 6 penetrates through the support tube 5, the upper end of the thermowell 6 stretches into the catalyst basket 4 along with the upper open end of the support tube 5, and the lower end of the thermowell 6 stretches out of the lower end of the lower sealing head 3. A thermocouple for measuring the temperature of the catalyst is arranged in the thermowell 6, the outer diameter of the thermowell 6 in the embodiment is 4mm, the wall thickness is 1mm, and the inner diameter of the thermocouple is 2mm.

The inner wall of the tube 1 is provided with a lining 101 near 300mm of the top end of the upper end, the bottom of the catalyst basket 4 is abutted against the surface of the lining 101 to fix the catalyst basket 4, the catalyst basket 4 is in an open shape, the whole is cylindrical, the bottom of the catalyst basket is conical, the outer diameter of the top of the basket cylinder is 24mm, the outer diameter of the bottom is 20mm, the wall thickness is 1mm, the height is 40mm, the bottom of the catalyst basket 4 is provided with an annular mounting groove 401 and a cross baffle 402, and a stainless steel micropore square mesh screen 403 is covered above the cross baffle 402.

The lower end of the supporting tube 5 is provided with external threads, a compression spring 7 and a compression nut 8 are sleeved outside the supporting tube 5 between the tube 1 and the lower sealing head 3, so that tension is formed to enable the bottom of the catalyst basket 4 to be abutted against the tube 1 and the liner 101, and further the catalyst basket 4 is fixed.

In this embodiment, a rectifying grid plate mounting groove 10 for mounting a rectifying grid plate 9 is provided in the tube 1 above the catalyst basket 4, and a sealing ring 11 is provided in the rectifying grid plate mounting groove 10. The rectifying grating plate 9 is placed on a step surface at the joint of the circular inner cavity at the upper end in the pipe barrel and the working cavity, and the inner part of the rectifying grating plate 9 is uniformly distributed with pore passages along the axial direction of the pipe barrel 1. The rectification grating plates 9 enable the speed and distribution of the passing reaction gas to be uniform, enable the gas to flow in the reaction tube along the axis of the catalyst reaction tube, enable the gas phase flow velocity to be uniformly distributed, and avoid back mixing of the gas flow.

In this embodiment, the upper end of the tube 1 is connected with the connecting piece 12 by adopting a flange 13, and the connecting piece 12 is in threaded connection with the upper end socket 2. The reaction tube inlet 102 is arranged above the tube barrel 1, the tube barrel 1 is in flange connection with the reaction tube inlet 102, the reaction tube inlet 102 is a stainless steel tube, the outer diameter is 8mm, and the wall thickness is 1mm. The side wall above the bottom end enclosure of the tube 1 is provided with a reaction tube outlet 103 at a position 50mm away from the lower end of the tube 1, in this embodiment, the reaction tube inlet 102 is in threaded connection with an external pipeline, and the reaction tube outlet 103 is in threaded connection with the external pipeline.

Another embodiment of the present invention provides a method for producing hydrogen by catalytic pyrolysis of methane, which is a reactor for producing hydrogen by catalytic pyrolysis of methane as set forth in any one of claims 1 to 9, comprising the steps of:

S1, before a methane catalytic cracking hydrogen production experiment is carried out, firstly, an upper end enclosure 2, a flange 13 and a rectifying grating plate 9 of a reactor are detached, a certain amount of catalyst is weighed and placed in a catalyst basket 4, before filling, a stainless steel micropore square screen 403 is required to cover a cross baffle 402 at the bottom of the catalyst basket 4;

S2, firstly, introducing inert gas nitrogen, removing air in the tube 1, heating the reactor at the same time, setting the reduction temperature to be 200-500 ℃, such as 300 ℃ specifically, the reduction pressure to be normal pressure, cutting off the nitrogen after the reduction temperature is raised to the top reduction temperature of the catalyst, introducing reducing gas hydrogen, and reducing the catalyst at the volume flow of 100-500ml/min at constant temperature;

S3, after the reduction is finished, closing a hydrogen valve, and under the purging of nitrogen, rapidly heating until the gas chromatograph does not detect hydrogen any more, and then introducing 99% pure methane to start the reaction;

The specific experimental operation conditions in the step are that the volume flow is 100-500ml/min, the reaction temperature is 700 ℃ and the reaction pressure is normal pressure. In the reaction process, the gas product firstly enters a condenser to condense heavy components in the product, and then enters a drying pipe to adsorb the water in the product. And measuring the volume flow of the dried gas product by a wet flowmeter, introducing a part of tail gas into an online gas chromatographic analyzer, and emptying the rest of tail gas. Gas samples of the gases reacted for 0.5h, 1.0h, 1.5h and 2.0h were taken and analyzed by chromatography. The gas chromatograph is 7890GC, TCD detector of Agilent company of America, the chromatographic column is 5A molecular sieve, ar gas is carrier gas;

and S4, after the experiment is finished, taking out the reactor from the heating furnace, then disassembling each part of the reactor in the reverse order, taking out the catalyst sample in the catalyst basket, and weighing.

Test example 1

The test example provides an online catalytic evaluation method of a catalyst A for producing hydrogen by methane catalytic cracking, wherein the composition of the catalyst A is 20 percent of Ni and 80 percent of magnesia-alumina spinel, and the preparation method comprises the following steps:

(1) Preparation of the solution

4.7G of nickel nitrate, 2.6g of magnesium nitrate and 7.5g of aluminum nitrate were dissolved in 450ml of aqueous solution to form solution I, and 11g of ammonium bicarbonate was prepared into 550ml of aqueous solution to obtain solution II.

(2) Preparation of the precipitate

The solution II was added dropwise to the vigorously stirred solution I at a rate of about 120ml/h, giving precipitate III.

(3) Preparation of the catalyst

Washing the obtained precipitate III by deionized water, filtering, drying a filter cake for 6 hours at 110 ℃, and roasting for 8 hours at 800 ℃ in an air atmosphere to obtain the catalyst.

The catalyst prepared by the reactor for preparing hydrogen by methane catalytic pyrolysis provided by the invention is subjected to catalyst evaluation.

Test example 2

The catalyst B consists of 20% Co and 80% magnesia-alumina spinel, the precipitant is ammonium bicarbonate, and the Co salt is cobalt nitrate. The catalyst was prepared in the same manner as "A".

Comparative example 1

The catalyst "C" consists of 10% Ni and 90% MgO, and the precipitant is ammonium bicarbonate. The catalyst was prepared in the same manner as "A".

Table 1 results of catalyst activity (methane conversion) for methane catalytic cracking hydrogen production measured in test examples and comparative examples

The present invention is not limited to the above-mentioned embodiments, and any equivalent embodiments which can be changed or modified by the technical content disclosed above can be applied to other fields, but any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical substance of the present invention without departing from the technical content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (10)

1. A reactor for producing hydrogen by methane catalytic cracking is characterized by comprising the following components:

The device comprises a pipe barrel, an upper sealing head connected to the upper end of the pipe barrel and a lower sealing head connected to the lower end of the pipe barrel;

A catalyst basket disposed within the barrel;

the support tube is of a hollow structure, the two ends of the support tube are both open ends, the upper open end of the support tube is connected to the bottom of the catalyst basket, and the lower open end of the support tube is abutted against the top of the lower seal head;

The thermowell penetrates through the supporting tube, the upper end of the thermowell stretches into the catalyst basket along with the upper opening end of the supporting tube, and the lower end of the thermowell stretches out of the lower end of the lower sealing head.

2. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 1, wherein a lining is arranged on the inner wall of the tube near the upper end, and the bottom of the catalyst basket is abutted against the surface of the lining to fix the catalyst basket.

3. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 1, wherein the catalyst basket is in an open shape, is in a cylindrical shape as a whole, and has a tapered bottom.

4. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 3, wherein the bottom of the catalyst basket is provided with an annular mounting groove and a cross baffle, and a mesh screen is covered above the cross baffle.

5. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 2, wherein an external thread is arranged at the lower end of the supporting tube, a compression spring and a compression nut are sleeved outside the supporting tube between the tube barrel and the lower end socket, and tension is formed to enable the bottom of the catalyst basket to be abutted against the tube barrel and the lining, so that the catalyst basket is fixed.

6. The reactor for producing hydrogen by catalytic cracking methane according to claim 1, wherein a rectifying grating plate mounting groove for mounting a rectifying grating plate is arranged in the tube barrel above the catalyst basket, and a sealing ring is arranged in the rectifying grating plate mounting groove.

7. The reactor for producing hydrogen by catalytic pyrolysis of methane as claimed in claim 6, wherein the rectifying grating plate is placed on a step surface at the joint of the circular inner cavity at the upper end in the pipe barrel and the working cavity, and the inner part of the rectifying grating plate is uniformly distributed with pore passages along the axial direction of the pipe barrel.

8. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 1, wherein the upper end of the pipe barrel is connected with a connecting piece by adopting a flange, and the connecting piece is connected with the upper sealing head.

9. The reactor for producing hydrogen by catalytic pyrolysis of methane according to claim 1, wherein the reaction tube inlet is arranged above the tube barrel, and the reaction tube outlet is arranged on the side wall above the sealing head at the bottom of the tube barrel.

10. A method for producing hydrogen by methane catalytic cracking, which adopts the reactor for producing hydrogen by methane catalytic cracking according to any one of claims 1-9, and is characterized by comprising the following steps:

S1, before a methane catalytic cracking hydrogen production experiment is carried out, an upper end socket, a flange and a rectifying grating plate of a reactor are removed, a certain amount of catalyst is weighed and placed into a catalyst basket, a stainless steel micropore square screen is required to cover a cross baffle plate at the bottom of the catalyst basket before filling, the rectifying grating plate, a connecting piece and the upper end socket at the upper end of a tube barrel of the reactor are fastened, a lower end socket is used for fastening the lower end of the tube barrel of the reactor, a thermocouple is inserted into a sleeve pipe of the reactor, the top end of the thermocouple is positioned in the catalyst basket, the reactor is selected and placed in a heating hearth, the catalyst basket is positioned in the middle of a heating section of the heating hearth, and then the experiment is started;

S2, firstly, introducing inert gas nitrogen, removing air in a tube, heating a reactor at the same time, setting the reduction temperature to be 200-500 ℃, setting the reduction pressure to be normal pressure, cutting off the nitrogen after the reduction temperature is raised to the top reduction temperature of the catalyst, introducing reducing gas hydrogen, and reducing the catalyst at a constant temperature;

s3, after the reduction is finished, closing a hydrogen valve, and under the purging of nitrogen, rapidly heating until the gas chromatograph does not detect hydrogen any more, and then introducing methane to start the reaction;

and S4, after the experiment is finished, taking out the reactor from the heating furnace, then disassembling each part of the reactor in the reverse order, taking out the catalyst sample in the catalyst basket, and weighing.