阅读说明：本技术 一种利用沼气制取氢气的方法 (Method for preparing hydrogen by utilizing methane ) 是由 周颖 张松林 周红军 于 2021-08-13 设计创作，主要内容包括：本发明提供了一种利用沼气制取氢气的方法。该方法包括以下步骤：将催化剂装填于反应器；将沼气和水输入反应器与催化剂接触转化为CO和H-(2)的合成气；催化剂为双功能催化剂,能够同时催化甲烷蒸汽转化与CO-(2)干重整反应。本发明采用的催化剂具有CH-(4)与水蒸气转化生产CO和H-(2)及甲烷与CO-(2)转化生产CO和H-(2)的功能,沼气加水蒸气后,沼气中的甲烷与水合沼气中的CO-(2)同时转化为CO和H-(2),沼气不需分离CO-(2),经催化剂转化生成为CO与H-(2)合成气,该合成气可以用于还原铁的生产,也可以历经传统的CO交换反应和变压吸附分离出H-(2),从而实现沼气不需脱除CO-(2)而双功能转化后,只需采用PSA一次脱除CO-(2)就可生产出绿色H-(2)。(The invention provides a method for preparing hydrogen by utilizing methane. The method comprises the following steps: filling a catalyst into a reactor; introducing marsh gas and water into a reactor to be contacted with a catalyst to be converted into CO and H 2 The synthesis gas of (2); the catalyst is a dual-function catalyst and can simultaneously catalyze methane steam conversion and CO 2 Dry reforming reaction. The catalyst employed in the present invention has CH 4 Conversion with steam to produce CO and H 2 And methane and CO 2 Conversion to produce CO and H 2 The function of the method is that after the biogas is added with water vapor, the methane in the biogas and the CO in the hydrated biogas 2 Simultaneous conversion to CO and H 2 The marsh gas does not need to separate CO 2 Is converted into CO and H by a catalyst 2 Synthesis gas, which can be used for the production of reduced iron and which can also undergo the conventional CO exchange reactions and transformationsPressure adsorption separation of H 2 Thereby realizing that the methane does not need to remove CO 2 After the double-function conversion, only PSA is used for removing CO once 2 Can produce green H 2 。)

1. A method for preparing hydrogen by utilizing marsh gas comprises the following steps:

filling a catalyst into a reactor;

introducing marsh gas and water into a reactor to be contacted with a catalyst to be converted into CO and H₂The synthesis gas of (2);

wherein the catalyst is a bifunctional catalyst capable of simultaneously catalyzing methane steam reforming and CO₂Dry reforming reaction.

2. The method of claim 1, wherein the active component of the catalyst is nickel, the promoter is an alkali metal and/or an alkaline earth metal, and the support is alumina;

based on the mass of the catalyst, the content of the active component is 1-20%, the content of the auxiliary agent is 0.1-10%, and the balance is the carrier.

3. The method of claim 1, wherein the reactor is an isothermal bed reactor.

4. The method as claimed in claim 3, wherein the temperature of the isothermal bed reactor is controlled to be 700-1000 ℃.

5. The process as claimed in claim 1, wherein the pressure of the conversion is from atmospheric pressure to 1.5MPa, and the space velocity is 600-4000h^-1The water-carbon ratio is 1-2.5: 1.

6. The method of claim 3, wherein the isothermal bed reactor is energized using an induction coil that is uniformly wound around the outside of the reaction tube.

7. The method of claim 6, wherein the frequency of the current input to the induction coil is a medium frequency or a high frequency, wherein the high frequency is 5-20KHz, preferably 8-16KHz, more preferably 10-15 KHz; the intermediate frequency is 50-3000Hz, preferably 300-2000 Hz.

8. The method of claim 7, wherein the frequency of the current input to the induction coil is adjusted by a power supply and a capacitance;

preferably, the induction coil is connected with the power supply to form a loop, and the power supply is connected with the capacitor in parallel;

more preferably, the power of the power supply is 100-1000KW, and more preferably 200-500 KW.

9. The method of claim 7 or 8, wherein the induction coil is selected from one or a combination of two or more of a ferrite coil, an iron core coil, an air core coil, and a copper core coil.

10. The method of claim 1, wherein the produced CO and H₂The synthesis gas is subjected to CO exchange reaction and pressure swing adsorption to separate H₂。

Technical Field

The invention relates to a method for preparing hydrogen by utilizing methane, belonging to the technical field of methane utilization.

Background

The method for preparing the green hydrogen mainly comprises two methods, one is the hydrogen production by electrolyzing water by green electricity such as photovoltaic wind power and the like, and the other is the production of methane by utilizing domestic garbage and rural waste through anaerobic fermentation and then converting the biological methane in the methane to prepare the green hydrogen.

The domestic garbage, kitchen garbage and kitchen garbage in cities, garbage landfill plants and the like can generate a large amount of methane through anaerobic fermentation, the methane is positively correlated with population of the cities, and the methane can make contribution to zero-carbon cities by converting the methane to prepare green hydrogen for logistics of urban public transportation.

Straws, livestock and poultry manure, agricultural and forestry wastes and the like of villages and towns can also produce a large amount of biogas through anaerobic fermentation, green hydrogen is prepared through the conversion of biological methane in the biogas, and then the green hydrogen is matched with a photovoltaic power grid, so that the rural zero-carbon traffic and green energy utilization can be realized.

The CO in the biogas must be removed firstly in the traditional biogas utilization method₂The concentration of methane is improved, and then the methane steam conversion can be carried out to produce hydrogen, so that the process is relatively complicated.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a method for producing hydrogen by using biogas, wherein the method comprises the steps of synchronously performing methane steam reforming and CO reforming₂Dry reforming reaction to obtain the product containing CO and H₂The synthesis gas of (2).

In order to achieve the aim, the invention provides a method for preparing H from methane₂The method of (a), comprising the steps of:

filling a catalyst into a reactor;

introducing marsh gas and water into a reactor to be contacted with a catalyst to be converted into CO and H₂The synthesis gas of (2);

wherein the catalyst is a bifunctional catalyst capable of simultaneously catalyzing methane steam reforming and CO₂Dry reforming reaction.

In the above method, preferably, the active component of the catalyst is nickel, the assistant is alkali metal and/or alkaline earth metal, and the carrier is alumina; based on the mass of the catalyst, the content of the active component is 1-20 percent (preferably 5-15 percent), the content of the auxiliary agent is 0.1-10 percent (preferably 0.3-10 percent), and the balance is the carrier. Wherein, the alkali metal as the auxiliary agent comprises K and the like, and the alkaline earth metal comprises Ca, Mg and the like. Wherein, the active component and the auxiliary agent are both in the form of oxides in the catalyst.

In the above method, preferably, the reactor is an isothermal bed reactor or a variable temperature bed reactor.

According to an embodiment of the present invention, when the isothermal bed reactor is used, the temperature of the isothermal bed reactor may be controlled to 700-. The specific process conditions for the conversion can be controlled as follows: the pressure is normal pressure-1.5 MPa (preferably 0.3-1.0MPa), the space velocity is 600-^-1(preferably 1000-3000 h)^-1) The water-carbon ratio is 1-2.5:1 (preferably 1-2).

According to the specific embodiment of the invention, the isothermal bed reactor adopted by the invention can be a tubular type, the catalyst is filled in the reaction tube, the induction coil is uniformly wound on the outer wall of the reaction tube, after the induction coil is electrified, electromagnetic induction is generated between the reaction tube and the induction coil, and the reaction tube generates heat, so that the raw materials in the reaction tube are heated. Wherein, the space between the reaction tube and the induction coil can be filled with heat insulation materials (such as cement, fireproof materials and the like).

According to a specific embodiment of the present invention, when the isothermal bed reactor is energized by using the induction coil, the induction coil is uniformly wound around the outside of the reaction tube. Conventional steam reforming device, dry reforming unit are through the burning heat supply of fuel, gas, the heat supply of burning is carried out through the nozzle in the combustion chamber, then realize the heating to the reaction tube through exchanging heat with the reaction tube, and then the raw materials in the heating reaction tube, however because the temperature of different regions is inhomogeneous in the combustion chamber, lead to this kind of heat transfer often all inhomogeneous, the heat can be concentrated in local area, can't realize that the temperature homoenergetic of each part of catalyst is evenly controlled, the transformation reaction is also inhomogeneous. The reaction tube is heated by the induction coil, so that the heating efficiency is high, and the induction coil is uniformly distributed in the reaction tube, so that the reaction tube can uniformly generate electromagnetic induction, and isothermal reaction can be really realized.

In the above method, preferably, the frequency of the current input to the induction coil is an intermediate frequency or a high frequency, wherein the high frequency is 5-20KHz, preferably 8-16KHz, more preferably 10-15KHz, further preferably 12-14KHz, and specifically may be 8KHz, 8.5KHz, 9KHz, 9.5KHz, 10KHz, 10.5KHz, 11KHz, 11.5KHz, 12KHz, 12.5KHz, 13KHz, 13.5KHz, 14KHz, 14.5KHz, 15KHz, 15.5KHz, 16KHz, or may be a range obtained by combining the endpoints of the above range and specific frequency values listed, such as 5-16KHz, 5-15KHz, 5-10KHz, 8-20KHz, 8-15KHz, 8-10KHz, 10-20KHz, 10-16KHz, 10-12KHz, 9-20KHz, 9-15KHz, 12-14KHz, 8-15KHz, 8-10KHz, 10-20KHz, 10-16KHz, 10-12KHz, 9-20KHz, 9-15KHz, 10-15KHz, 9-14 KHz, 11KHz, and 10KHz, 12-20 KHz; the intermediate frequency is 50-3000Hz, preferably 300-2000Hz, more preferably 600-1500Hz, and specifically can be 300Hz, 400Hz, 500Hz, 600Hz, 700Hz, 800Hz, 900Hz, 1000Hz, 1100Hz, 1200Hz, 1300Hz, 1400Hz, 1500Hz, 1600Hz, 1700Hz, 1800Hz, 1900Hz, 2000Hz, or can be the end point of the above range and the range obtained by combining the specific frequency values listed, such as 300-3000Hz, 300-1500Hz, 600-3000Hz, 600-2000Hz, 1000-3000Hz, 1000-2000Hz, 1200-2000Hz, 1500-3000Hz, 1500-2000Hz, and the like.

In the above method, preferably, the frequency of the current input to the induction coil is adjusted by a power supply and a capacitor. The induction coil is connected with the power supply to form a loop, and the power supply is connected with the capacitor in parallel, as shown in fig. 1. The power supply used in the present invention may be a common industrial power supply, such as a medium frequency power supply and a high frequency power supply. The specification parameters such as the power of the power supply can be selected according to the frequency adjusted as required, and the rated power of the power supply is preferably 100-1000KW, and more preferably 200-500 KW. The specification of the capacitor can be selected according to the requirement, and the capacitor can be matched with a power supply to meet the frequency control requirement.

The induction coil used in the present invention may be one or a combination of two or more selected from ferrite coil, iron core coil, air core coil, copper core coil, and the like.

According to the specific embodiment of the present invention, the size of the reaction tube used in the present invention can be selected according to the need, wherein the inner diameter of the reaction tube can be 50-250mm, and the length can be selected according to the need of the reaction.

According to embodiments of the present invention, the material of the reaction tubes may be a metal or an alloy, respectively, including but not limited to the materials of reaction tubes generally used for steam reforming, reaction tubes for dry reforming. The metal or alloy is preferably one that can withstand a temperature of 1000 c, more preferably one that can withstand a temperature of 1200 c. The material of the reaction tube can be respectively selected from 316L stainless steel, 304S stainless steel, HK40 high-temperature furnace tube material, HP40 high-temperature furnace tube material, HP Micro Alloy steel or material for a Manaurite XTM steam cracking furnace, and the like.

In the above process, preferably, the obtained CO and H are produced₂The synthesis gas is subjected to CO exchange reaction and pressure swing adsorption to separate H₂。

According to the technical scheme provided by the invention, photovoltaic wind power and other green electricity are supplied to methane through the intermediate frequency furnace and converted into synthesis gas by adding a water isothermal bed, and the synthesis gas can be used for providing green hydrogen with zero carbon footprint by CO conversion and pressure swing adsorption. The green source of electricity includes one or a combination of two or more of electricity obtained by photovoltaic power generation, wind power generation, and hydroelectric power generation.

The bifunctional catalyst employed in the present invention has CH₄Conversion with steam to produce CO and H₂And methane and CO₂Conversion to produce CO and H₂The function of the method is that after the biogas is added with water vapor, the methane in the biogas and the CO in the hydrated biogas₂Simultaneous conversion to CO and H₂The marsh gas does not need to separate CO₂Compared with the prior art, the method can omit the CO removal of the methane₂The process of converting the mixture into CO and H by the bifunctional catalyst₂Synthesis gas, which may beCan be used for producing reduced iron, and can also be subjected to conventional CO exchange reaction and Pressure Swing Adsorption (PSA) to separate H₂Thereby realizing that the methane does not need to remove CO₂After the double-function conversion, only PSA is used for removing CO once₂Can produce green H₂。

Drawings

FIG. 1 is a schematic circuit diagram of a power supply, an induction coil, and a capacitor according to the present invention.

FIG. 2 is a schematic view of a reaction apparatus for examples 1 to 6.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Examples

Examples 1 to 6 respectively provide a method for producing hydrogen using biogas, wherein the raw material biogas used comprises the following main components: CH (CH)₄、55％；CO₂、45％，H₂S < 5ppm, the catalysts used are shown in Table 1, and the reaction conditions and results are shown in Table 2.

TABLE 1

Catalyst and process for preparing same	Ni，％	K2O，％	CaO，％	MgO，％	Al2O3
						MC6-1	5	0.3	-	-	Balance of
MC6-2	10	-	5	-	Balance of
						MC6-3	15	-	-	10	Balance of

TABLE 2

This example employs an isothermal bed reactor with induction coils to heat the reaction tubes, as shown in FIG. 2. The left diagram in fig. 2 is a schematic diagram of the catalyst packing pattern, wherein the packing is generally used near the inlet and the catalyst bed is below. The right drawing in fig. 2 is a schematic view showing the winding manner of the induction coil uniformly wound on the outer wall of the reaction tube corresponding in height to the height of the catalyst inside the reaction tube.

As can be seen from the data in table 2: under the action of the bifunctional catalyst, the marsh gas does not remove CO₂In the case ofThe conversion is completed, and the product with high content of H is obtained₂And a product gas of CO, the CO concentration in the product gas being higher.

The water-carbon ratio for steam reforming of methane, which is common in industry, needs to reach 3: 1, to ensure the conversion rate of methane, and the methane is subjected to CO removal₂And then steam reforming is carried out by using methane with higher concentration, so that carbon deposition is easily caused. The technical scheme of the invention does not remove CO₂The methane steam conversion is carried out under the condition of (1), the reaction is carried out at a lower water-carbon ratio, the higher methane conversion rate can still be ensured, and carbon deposition can be avoided.