阅读说明：本技术 一种使用有序介孔材料的正仲氢转化催化剂及其制备方法 (Ortho-para hydrogen conversion catalyst using ordered mesoporous material and preparation method thereof ) 是由 景航昆 李梦竹 丁明伟 蒋榕培 孙海云 方涛 杨思锋 于 2020-12-14 设计创作，主要内容包括：本发明涉及一种液氢生产及储存装置使用的正仲氢转化催化剂及其制备方法。特别涉及使用有序介孔材料为载体,使用化学沉淀的方法浸渍焙烧后再成型制备的负载型正仲氢转化催化剂。使用有序介孔材料做载体可有效减少氢气分子进入载体的无效路径,提升氢气分子在载体内表面的吸附速率,有助于减少装置的流阻,提高正仲氢催化转化反应在不同空速下的仲氢转化率。相比于先成型再浸渍的方法而言,先浸渍焙烧再成型可以增大载体与活性物质的接触面积,从而增加催化反应的活性位点,提高催化剂的正仲氢催化转化活性。(The invention relates to an orthopara-hydrogen conversion catalyst used in a liquid hydrogen production and storage device and a preparation method thereof. In particular to a supported orthohydrogen conversion catalyst which is prepared by using an ordered mesoporous material as a carrier, impregnating, roasting and then molding by using a chemical precipitation method. The ordered mesoporous material is used as the carrier, so that an invalid path for hydrogen molecules to enter the carrier can be effectively reduced, the adsorption rate of the hydrogen molecules on the inner surface of the carrier is improved, the flow resistance of the device is reduced, and the parahydrogen conversion rate of the catalytic conversion reaction of the parahydrogen at different airspeeds is improved. Compared with the method of forming before impregnating, the method of impregnating, roasting and forming can increase the contact area of the carrier and the active substance, thereby increasing the active sites of catalytic reaction and improving the catalytic conversion activity of the catalyst.)

1. A supported ortho-para hydrogen conversion catalyst characterized by: the catalyst comprises an ordered mesoporous carrier and a metal oxide;

the ordered mesoporous carrier is at least one of ordered mesoporous molecular sieve, ordered mesoporous activated carbon, ordered mesoporous titanium dioxide, ordered mesoporous silicon oxide or ordered mesoporous aluminum oxide;

the metal in the metal oxide is at least one of iron, chromium, copper, ruthenium, molybdenum, nickel or manganese;

the mass of the metal oxide is 5-30% of the mass of the catalyst.

2. A supported parahydrogen conversion catalyst according to claim 1, wherein: the ordered mesoporous molecular sieve is SBA-15, MCM-41 or MCM-48.

3. A supported parahydrogen conversion catalyst according to claim 1, wherein: the ordered mesoporous activated carbon is CMK-3.

4. A supported parahydrogen conversion catalyst according to claim 1, wherein: the ordered mesoporous carrier has a powdery macroscopic morphology.

5. A process for the preparation of a supported ortho-para hydroconversion catalyst, characterized in that the process comprises the steps of:

firstly, dipping ordered mesoporous carrier powder into an active substance salt solution, and drying at 30-120 ℃ after dipping for 5-30 h;

secondly, adding the dried ordered mesoporous carrier into a sodium hydroxide solution, generating hydroxide precipitates of active substances on the surface of the ordered mesoporous carrier through precipitation reaction, filtering after complete reaction, and drying at the temperature of 30-120 ℃ to obtain a carrier with the surface loaded with the active hydroxide precipitates;

thirdly, putting the carrier with the active hydroxide sediment loaded on the surface into a tubular furnace, and roasting for 1-5h at the temperature of 300-800 ℃ to finally generate the powder catalyst with the active oxide loaded with the ordered mesoporous carrier;

and fourthly, extruding or tabletting the binder in the powder catalyst obtained in the third step, and roasting at the temperature of 400-900 ℃ for 3-8h to remove the binder to obtain the orthosteric hydrogen conversion catalyst.

6. A process for preparing a supported ortho-para-hydrogen conversion catalyst as recited in claim 1, wherein: in the first step, the active substance salt solution is an iron nitrate solution, an iron chloride solution, a chromium nitrate solution, a chromium chloride solution, a copper nitrate solution, a copper chloride solution, a ruthenium nitrate solution, a ruthenium chloride solution, a molybdenum nitrate solution, a molybdenum chloride solution, a nickel nitrate solution, a nickel chloride solution, a manganese nitrate solution, or a manganese chloride solution.

7. A process for preparing a supported ortho-para-hydrogen conversion catalyst as recited in claim 1, wherein: in the first step, the mass concentration of the active substance salt solution is 5-25%.

8. A process for preparing a supported ortho-para-hydrogen conversion catalyst as recited in claim 1, wherein: in the second step, the mass fraction of the sodium hydroxide solution is 5-25%.

9. A process for preparing a supported ortho-para-hydrogen conversion catalyst as recited in claim 1, wherein: in the fourth step, the binder is hydrochloric acid or PVD, and the mass of the binder is 10% -20% of the mass sum of the binder and the powder type catalyst.

10. A process for preparing a supported ortho-para-hydrogen conversion catalyst as recited in claim 1, wherein: the obtained orthohydrogen reforming catalyst was placed in a catalyst activity evaluation device at a liquid nitrogen temperature, and data were collected by a gas chromatograph and measured at 50, 300, and 600L, respectively_H2/L_{Catalyst and process for preparing same}Catalyst activity in liquid nitrogen temperature region at/min space velocity.

Technical Field

The invention relates to an ortho-para hydrogen conversion catalyst used for a liquid hydrogen production and storage device and a preparation method thereof, in particular to an ortho-para hydrogen conversion catalyst prepared by using an ordered mesoporous material as a carrier and a preparation method thereof.

Background

The production and storage of liquid hydrogen is one of the issues of concern in the hydrogen energy field today. Hydrogen molecules are classified into two forms according to their own nuclear spin patterns. Wherein, the two atomic nuclei have the same spin direction and are orthohydrogen, and the two atomic nuclei have the opposite spin directions and are parahydrogen. The normal hydrogen accounts for 75% and the parahydrogen accounts for 25% at normal temperature. As the temperature decreases, ortho-hydrogen slowly transitions to para-hydrogen. The proportion of orthohydrogen to parahydrogen is close to that of the liquid nitrogen temperature zone, the proportion of orthohydrogen is 50.1%, and the proportion of parahydrogen is 49.9%. When the liquid hydrogen temperature is reached, the para-hydrogen content approaches 100%. The process of conversion of orthohydrogen to parahydrogen is a spontaneous process, but is extremely slow and typically requires a catalyst to drive the reaction. The significance of improving the conversion efficiency of orthohydrogen to parahydrogen is great. Aiming at the storage process of liquid hydrogen, the conversion process of orthohydrogen to parahydrogen is an exothermic process, so that the liquid hydrogen is volatilized continuously, and the development of a high-efficiency low-temperature orthohydrogen conversion catalyst is very important for the production and storage of the liquid hydrogen.

The existing hydrous iron oxide catalyst used in production has the characteristics of low flow resistance, easy pulverization and the like, so that the search for a catalyst with low flow resistance and high performance is very important.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the existing catalyst, provides an ortho-para hydrogen conversion catalyst using an ordered mesoporous material and a preparation method thereof, and aims to develop a supported catalyst with high catalytic activity and low flow resistance aiming at the problems of large flow resistance, easy pulverization and the like of a hydrous iron oxide catalyst bed layer.

The technical solution of the invention is as follows:

a supported ortho-para hydrogen conversion catalyst comprising an ordered mesoporous support and a metal oxide;

the ordered mesoporous carrier is at least one of ordered mesoporous molecular sieve, ordered mesoporous activated carbon, ordered mesoporous titanium dioxide, ordered mesoporous silicon oxide or ordered mesoporous aluminum oxide;

the ordered mesoporous molecular sieve is SBA-15, MCM-41 or MCM-48;

the ordered mesoporous activated carbon is CMK-3;

the ordered mesoporous carrier has a powdery macroscopic morphology;

the metal in the metal oxide is at least one of iron, chromium, copper, ruthenium, molybdenum, nickel or manganese;

the mass of the metal oxide is 5-30% of the mass of the catalyst.

A method for preparing a supported ortho-para hydroconversion catalyst, the method comprising the steps of:

firstly, dipping the ordered mesoporous carrier powder into an active substance salt solution with the mass fraction of 5-25%, and drying at 30-120 ℃ after dipping for 5-30 h;

the active substance salt solution is ferric nitrate solution, ferric chloride solution, chromium nitrate solution, chromium chloride solution, copper nitrate solution, copper chloride solution, ruthenium nitrate solution, ruthenium chloride solution, molybdenum nitrate solution, molybdenum chloride solution, nickel nitrate solution, nickel chloride solution, manganese nitrate solution or manganese chloride solution;

secondly, adding the dried ordered mesoporous carrier into a sodium hydroxide solution, generating hydroxide precipitates of active substances on the surface of the ordered mesoporous carrier through precipitation reaction, filtering after complete reaction, and drying at the temperature of 30-120 ℃ to obtain a carrier with the surface loaded with the active hydroxide precipitates, wherein the mass fraction of the sodium hydroxide solution is 5% -25%;

thirdly, putting the carrier with the active hydroxide sediment loaded on the surface into a tubular furnace, and roasting for 1-5h at the temperature of 300-800 ℃ to finally generate the powder catalyst with the active oxide loaded with the ordered mesoporous carrier;

and step four, adding a binder into the powder catalyst obtained in the step three, extruding into strips or tabletting into pieces, roasting at the temperature of 400-900 ℃ for 3-8h to remove the binder, and preparing the catalyst with the macroscopic shape of particles or tablets to obtain the orthosteric hydrogen conversion catalyst.

The binder is hydrochloric acid or PVDF, and the mass concentration of the hydrochloric acid is not more than 10%;

the mass of the binder is 10-20% of the sum of the mass of the binder and the mass of the powder catalyst;

the molded catalyst was placed in a catalyst activity evaluation apparatus at a liquid nitrogen temperature, and data were collected by a gas chromatograph and measured at 50, 300, and 600L, respectively_H2/L_{Catalyst and process for preparing same}Catalyst activity in liquid nitrogen temperature region at/min space velocity.

Advantageous effects

The invention relates to an orthopara-hydrogen conversion catalyst used in a liquid hydrogen production and storage device and a preparation method thereof. In particular to a supported orthohydrogen conversion catalyst which is prepared by using an ordered mesoporous material as a carrier, impregnating, roasting and then molding by using a chemical precipitation method. The ordered mesoporous material is used as the carrier, so that an invalid path for hydrogen molecules to enter the carrier can be effectively reduced, the adsorption rate of the hydrogen molecules on the inner surface of the carrier is improved, the flow resistance of the device is reduced, and the parahydrogen conversion rate of the catalytic conversion reaction of the parahydrogen at different airspeeds is improved. Compared with the method of forming before impregnating, the method of impregnating, roasting and forming can increase the contact area of the carrier and the active substance, thereby increasing the active sites of catalytic reaction and improving the catalytic conversion activity of the catalyst.

The invention relates to a novel preparation method for preparing an orthosteric hydrogen conversion catalyst by using an ordered mesoporous material as a carrier, which mainly solves the problems of large flow resistance, easy powder falling and the like of a device caused by a traditional hydrated iron oxide catalyst. The preparation method adopts an ordered mesoporous material as a carrier, salts of active substances are adsorbed on the inner surface of the carrier through the first step of impregnation, the treated carrier is soaked in a sodium hydroxide solution again after being dried, hydroxide of the active substances is generated on the inner surface of the carrier, and then the active substances are changed into oxides through roasting. After being bonded by using a binder, the catalyst is extruded into strips or tablets, and the catalyst is calcined at high temperature to change the powdery catalyst into a catalyst with a macroscopic form of particles or tablets. The preparation method is simple and environment-friendly, the invalid path of hydrogen molecules entering the carrier can be effectively reduced by using the ordered mesoporous material as the carrier, the adsorption rate of the hydrogen molecules on the inner surface of the carrier is improved, the flow resistance of the device is favorably reduced, and the parahydrogen conversion rate of the catalytic conversion reaction of the parahydrogen at different airspeeds is improved. The catalyst is formed by soaking and roasting, and then the catalyst is molded, so that the contact area between the carrier and the active substance can be increased, the active sites of the catalytic reaction are increased, and the catalytic conversion activity of the catalyst for the para-hydrogen is improved.

Detailed Description

A supported ortho-para hydrogen conversion catalyst comprising an ordered mesoporous support and a metal oxide;

the ordered mesoporous carrier is at least one of ordered mesoporous molecular sieve, ordered mesoporous activated carbon, ordered mesoporous titanium dioxide, ordered mesoporous silicon oxide or ordered mesoporous aluminum oxide;

the ordered mesoporous molecular sieve is SBA-15, MCM-41 or MCM-48;

the ordered mesoporous activated carbon is CMK-3;

the ordered mesoporous carrier has a powdery macroscopic morphology;

the metal in the metal oxide is at least one of iron, chromium, copper, ruthenium, molybdenum, nickel or manganese;

the mass of the metal oxide is 5-30% of the mass of the catalyst.

A method for preparing a supported ortho-para hydroconversion catalyst, the method comprising the steps of:

firstly, dipping the ordered mesoporous carrier powder into an active substance salt solution with the mass fraction of 5-25%, and drying at 30-120 ℃ after dipping for 5-30 h;

the active substance salt solution is ferric nitrate solution, ferric chloride solution, chromium nitrate solution, chromium chloride solution, copper nitrate solution, copper chloride solution, ruthenium nitrate solution, ruthenium chloride solution, molybdenum nitrate solution, molybdenum chloride solution, nickel nitrate solution, nickel chloride solution, manganese nitrate solution or manganese chloride solution;

secondly, adding the dried ordered mesoporous carrier into a sodium hydroxide solution, generating hydroxide precipitates of active substances on the surface of the ordered mesoporous carrier through precipitation reaction, filtering after complete reaction, and drying at the temperature of 30-120 ℃ to obtain a carrier with the surface loaded with the active hydroxide precipitates, wherein the mass fraction of the sodium hydroxide solution is 5% -25%;

thirdly, putting the carrier with the active hydroxide sediment loaded on the surface into a tubular furnace, and roasting for 1-5h at the temperature of 300-800 ℃ to finally generate the powder catalyst with the active oxide loaded with the ordered mesoporous carrier;

and step four, adding a binder into the powder catalyst obtained in the step three, extruding into strips or tabletting into pieces, roasting at the temperature of 400-900 ℃ for 3-8h to remove the binder, and preparing the catalyst with the macroscopic shape of particles or tablets to obtain the orthosteric hydrogen conversion catalyst.

The mass of the binder is 10-20% of the sum of the mass of the binder and the mass of the powder catalyst;

the binder is hydrochloric acid or PVDF, and the mass concentration of the hydrochloric acid is not more than 10%;

the molded catalyst was placed in a catalyst activity evaluation apparatus at a liquid nitrogen temperature, and data were collected by a gas chromatograph and measured at 50, 300, and 600L, respectively_H2/L_{Catalyst and process for preparing same}Catalyst activity in liquid nitrogen temperature region at/min space velocity.

The present invention will be further described with reference to the following examples.

Example 1

The SBA-15 carrier purchased was used, and immersed in a nickel nitrate solution with a mass fraction of 5%, and dried at 100 ℃ after 5 hours of immersion. Preparing a sodium hydroxide solution with the mass fraction of 5%, adding the impregnated and dried SBA-15 carrier into the sodium hydroxide solution, filtering after 2h, drying at 100 ℃, then putting into a tubular furnace for roasting at 500 ℃ for 5h, adding a binder into the roasted product, tabletting and forming, roasting at 600 ℃ for 4h to remove the binder, and preparing the tablet NiO/SBA-15 catalyst. The mass of the binder is 10% of the mass sum of the binder and the roasted product; the binder is hydrochloric acid with the concentration of 10 percent;

placing the prepared NiO/SBA-15 catalyst in a catalyst activity evaluation device at the temperature of liquid nitrogen, collecting data by adopting a gas chromatograph, and respectively measuring 50L_H2/L_{Catalyst and process for preparing same}/min，300L_H2/L_{Catalyst and process for preparing same}/min,600L_H2/L_{Catalyst and process for preparing same}Catalyst activity at/min space velocity. The activity test results are as follows:

TABLE 1 para-Hydrogen conversion of Nickel-based catalysts

Airspeed	50 L/L/min	300L/L/min	600L/L/min
				Para-hydrogen conversion	99.9％	96％	94.5％

Example 2

The MCM-41 carrier purchased is used and is immersed in ferric nitrate solution with the mass fraction of 5%, and after 5 hours of immersion, the MCM-41 carrier is dried at 100 ℃. Preparing a sodium hydroxide solution with the mass fraction of 5%, adding the impregnated and dried MCM-41 carrier into the sodium hydroxide solution, filtering after 2h, drying at 100 ℃, and then putting into a tubular furnace for roasting at 600 ℃ for 5 h. Adding a binder into the roasted product, tabletting and forming, roasting at 600 ℃ for 4h to remove the binder, and preparing the tablet Fe₂O₃A/MCM-41 catalyst. The mass of the binder is 10% of the mass sum of the binder and the roasted product; the binder is hydrochloric acid with the concentration of 10 percent;

at the temperature of liquid nitrogen, Fe to be prepared₂O₃Catalyst activity evaluation of/MCM-41 catalystIn the device, data were collected by gas chromatograph and 50L of the sample was measured_H2/L_{Catalyst and process for preparing same}/min，300L_H2/L_{Catalyst and process for preparing same}/min,600L_H2/L_{Catalyst and process for preparing same}Catalyst activity at/min space velocity. The activity test results are as follows:

TABLE 2 para-Hydrogen conversion of iron-based catalysts

Airspeed	50 L/L/min	300L/L/min	600L/L/min
				Para-hydrogen conversion	99.9％	96.5％	94.1％

Example 3

The CMK-3 carrier purchased is used and is immersed in a chromium nitrate solution with the mass fraction of 5 percent, and after 5 hours of immersion, the carrier is dried at 100 ℃. Preparing a sodium hydroxide solution with the mass fraction of 5%, adding the soaked and dried CMK-3 carrier into the sodium hydroxide solution, filtering after 2h, drying at 100 ℃, and then putting into a tubular furnace to roast at 600 ℃ for 5 h. Adding a binder into the roasted product, tabletting and forming, roasting at 600 ℃ for 4h to remove the binder, and preparing the tablet Cr₂O₃a/CMK-3 catalyst. The mass of the binder is 10% of the mass sum of the binder and the roasted product; the binder is hydrochloric acid with the concentration of 10 percent;

at the temperature of liquid nitrogen, the preparationOf Cr (C)₂O₃the/CMK-3 catalyst is placed in a catalyst activity evaluation device, and 50L of the catalyst activity evaluation device is respectively measured by collecting data by a gas chromatograph_H2/L_{Catalyst and process for preparing same}/min，300L_H2/L_{Catalyst and process for preparing same}/min,600L_H2/L_{Catalyst and process for preparing same}Catalyst activity at/min space velocity. The activity test results are as follows:

TABLE 3 para-Hydrogen conversion of chromium-based catalysts

Airspeed	50 L/L/min	300L/L/min	600L/L/min
				Para-hydrogen conversion	99.9％	95.9％	93.7％

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.