阅读说明：本技术 一种碳化物/氮化碳硫化氢选择性氧化脱硫催化剂及其制备方法 (Selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and preparation method thereof ) 是由 雷永鹏 周科朝 周雯 刘毅 于 2019-04-10 设计创作，主要内容包括：本发明涉及一种碳化物/氮化碳硫化氢选择性氧化脱硫催化剂及其制备方法,属于催化剂合成技术领域。其特征在于所述的催化剂中氮化碳与碳化物的质量比为(0～20)：(1～10)。该催化剂在空速为6000mL/(g*h)时,190℃硫化氢转化率大于99％,同时具有高稳定性,经过28小时反应后,其转化率仍大于85％,有效提高了氮化碳催化剂的选择性氧化脱硫性能。(The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, belonging to the technical field of catalyst synthesis. The catalyst is characterized in that the mass ratio of carbon nitride to carbide in the catalyst is (0-20): (1-10). When the air speed of the catalyst is 6000mL/(g h), the conversion rate of hydrogen sulfide at 190 ℃ is more than 99%, and the catalyst has high stability, and after 28 hours of reaction, the conversion rate is still more than 85%, so that the selective oxidation desulfurization performance of the carbon nitride catalyst is effectively improved.)

1. The preparation method of the catalyst for selective oxidative desulfurization of carbide/carbon nitride hydrogen sulfide comprises the following steps of firstly preparing carbon nitride, mixing and grinding the carbon nitride, metal salt and sugar, then carrying out heat treatment to prepare carbide, then mixing the carbide and the carbon nitride to obtain a mixture, and finally carrying out heat treatment on the mixture to prepare a final product, wherein the specific steps are as follows:

1) weighing a certain mass of carbon nitride precursor, placing the carbon nitride precursor in a crucible, placing the crucible in a muffle furnace, setting a heating program, heating to 450-600 ℃ at a heating rate of 2-10 ℃/min, keeping the temperature for 0.5-10h for heat treatment, and taking out a product (carbon nitride) when the temperature of the muffle furnace naturally drops to room temperature;

2) respectively weighing metal salt, sugar and the carbon nitride obtained in the step 1), and mixing and grinding the metal salt, the sugar and the carbon nitride for 10-300min according to a certain mass ratio to obtain a mixture A;

3) placing the mixture A in the step 2) in a tube furnace, setting a temperature-raising program, raising the temperature to 500-1000 ℃ at a temperature-raising rate of 2-10 ℃/min under an inert gas atmosphere, and carrying out heat treatment for 0.5-10h, and taking out a product (metal carbide) when the temperature of the tube furnace is naturally reduced to room temperature;

4) mixing and grinding the carbon nitride obtained in the step 1) and the metal carbide obtained in the step 3) for 10-300min according to a certain mass ratio to obtain a mixture B;

5) placing the mixture B in the step 4) in a tube furnace, setting a temperature-raising program, raising the temperature to room temperature-600 ℃ at a temperature-raising rate of 2-10 ℃/min under an inert gas atmosphere, preserving the temperature for 0.5-10h for heat treatment, and taking out the catalyst when the temperature of the tube furnace is naturally reduced to room temperature.

2. The method according to claim 1, wherein the sugar in step 2) is at least one of glucose, sucrose, polysaccharide, etc., preferably glucose; the metal salt in the step 2) includes metal halide, metal nitrate, metal sulfate, alkali metal salt, nitrite, carbonate, phosphate, borate, etc., wherein the metal in the metal salt is at least one element of iron, nickel, molybdenum, cobalt, magnesium, aluminum, calcium, zirconium, tungsten, etc., preferably molybdenum, aluminum, etc.

3. The method according to claim 1, wherein the steps 4) and 5) are optional steps, and the metal carbide prepared in the step 3), the mixture B and the sample after the step 5) are all hydrogen sulfide selective oxidation catalysts.

4. The method according to claim 1, wherein the mass ratio of the metal salt, the sugar and the carbon nitride in the step 2) is (1-10): (1-10): (1-10), wherein the mass ratio of the carbon nitride to the metal carbide in the step 4 is (0-20): (1-10).

5. The method according to claim 1, wherein the catalyst is used for selective oxidation of a hydrogen sulfide-containing mixed gas.

Technical Field

The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, belonging to the technical field of catalyst synthesis.

Background

Hydrogen sulfide is a highly toxic gas discharged from chemical industrial processes, for example, natural gas processing and utilization, crude oil hydrodesulfurization, coal chemistry and the like all release hydrogen sulfide, which brings great harm to human beings and the environment, and even death can be caused when the concentration of the hydrogen sulfide is more than 700 ppm. In addition, hydrogen sulfide, whether in gaseous or solution form, is extremely corrosive.

At present, the hydrogen sulfide removal technology mainly comprises three technologies, including a low-temperature Claus reaction process, reduction absorption and selective oxidation of hydrogen sulfide, wherein the selective oxidation of hydrogen sulfide is not limited by thermodynamic equilibrium and has low energy consumption, and the technology has development prospects. The hydrogen sulfide selective oxidation desulfurization catalyst includes metal oxides, carbon materials and the like. The metal oxide desulfurization catalyst has high conversion efficiency and selectivity, is suitable for continuous reaction, and has high airspeed and wide application. However, metals tend to form metal-sulfur bonds with the sulfur element in hydrogen sulfide, resulting in reduced stability of the metal oxide (see ACS cat., 2015,5, 1053). Therefore, it is very urgent to develop a desulfurization catalyst having both high hydrogen sulfide conversion efficiency and high stability.

The commonly used carbon-based desulfurization catalyst mainly comprises activated carbon, carbon nano tubes, carbon nano fibers and the like. The active carbon has rich micropores, large specific surface, high pore volume, rich surface acidity and alkalinity and good modifiability, and can physically adsorb hydrogen sulfide into the micropore channels thereof, and then dissociate the hydrogen sulfide into hydrogen sulfide radicals and further oxidize the hydrogen sulfide radicals into sulfur in the presence of oxygen. However, sulfur formed in this process is directly deposited in the micropores, and the desulfurization catalyst is deactivated. Nitrogen doping can regulate and control the surface acidity and alkalinity of the carbon material and improve the conversion rate of the carbon desulfurization catalyst, so that the nitrogen doping of the carbon material to improve the hydrogen sulfide selective oxidation catalytic performance of the material is attractive (see ChemCatChem,2015,7, 2957). Carbon nitride is a structurally stable nitrogen-rich carbon material with abundant surface properties, rich electron and basic surface groups, and catalytic properties for selective oxidation of hydrogen sulfide (see chem. commun.,2018,54, 2475-2478). However, the conversion rate and stability of selective oxidative desulfurization of carbon nitride are still low, and improvement is needed.

Disclosure of Invention

The main purpose of the present invention is to provide a hydrogen sulfide selective oxidation desulfurization catalyst and a preparation method thereof, so as to improve the problem of low desulfurization efficiency (only 82% at 250 ℃) of a carbon nitride catalyst, wherein the catalyst has good hydrogen sulfide conversion rate (metal carbide can be higher than 99% at 160 ℃, and metal carbide/carbon nitride can be higher than 99% at 190 ℃) and good stability.

In order to achieve the aim, the invention provides a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof. The method specifically comprises the following steps:

1) weighing a certain mass of carbon nitride precursor, placing the carbon nitride precursor in a crucible, placing the crucible in a muffle furnace, setting a temperature rise program, raising the temperature to 450-600 ℃ at the speed of 2-10 ℃/min, keeping the temperature for 0.5-10h for heat treatment, and taking out a product (carbon nitride) when the temperature of the muffle furnace is naturally reduced to room temperature;

2) weighing a certain mass of metal salt, sugar and the carbon nitride obtained in the step 1), and mixing and grinding the metal salt, the sugar and the carbon nitride for 10-300min according to a certain mass ratio to obtain a mixture A;

3) placing the mixture A in the step 2) in a tube furnace, setting a temperature-raising program, carrying out heat treatment in an inert gas atmosphere, and taking out a product (metal carbide) when the temperature of the tube furnace is naturally reduced to room temperature;

4) mixing and grinding the carbon nitride obtained in the step 1) and the metal carbide obtained in the step 3) for 10-300min according to a certain mass ratio to obtain a powdery mixture B;

5) placing the powdery mixture B in the step 4) in a tubular furnace, setting a temperature-raising program, carrying out heat treatment in an inert gas atmosphere, and taking out the catalyst after the temperature of the tubular furnace is naturally reduced to room temperature.

The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, wherein a carbon nitride precursor can be selected from at least one of dicyanodiamine, melamine, urea and the like.

The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, wherein metal salts comprise metal halides, metal nitrates, metal sulfates, alkali metal salts, nitrites, carbonates, phosphates, borates and the like, wherein the metal in the metal salts is at least one element of iron, nickel, molybdenum, cobalt, magnesium, aluminum, calcium, zirconium, tungsten and the like, and preferably molybdenum, aluminum and the like.

The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, wherein sugar is at least one of glucose, sucrose, polysaccharide and the like, and is preferably glucose.

The invention relates to a selective oxidation desulfurization catalyst for carbide/carbon nitride hydrogen sulfide and a preparation method thereof, wherein in the step 2), the mass ratio of metal salt, sugar and carbon nitride is (1-10): (1-10): (1-10), wherein the mass ratio of the carbon nitride to the metal carbide in the step 4 is (0-20): (1-10).

The preparation method of the carbide/carbon nitride hydrogen sulfide selective oxidation desulfurization catalyst comprises the following steps of 3), wherein the heating rate is 2-10 ℃/min, the temperature is 500-.

The preparation method of the carbide/carbon nitride hydrogen sulfide selective oxidation desulfurization catalyst comprises the step 5), wherein the heating rate is 2-10 ℃/min, the heat treatment temperature is between room temperature and 600 ℃, the gas flow rate is 10-200mL/min, and the heat preservation duration is preferably 30-240 min.

The invention also provides a catalyst prepared by the preparation method of the carbide/carbon nitride hydrogen sulfide selective oxidation desulfurization catalyst.

The invention has the beneficial effects that:

1) in order to be widely applied to the selective oxidation catalytic reaction of hydrogen sulfide, the selected metal source, carbon source and nitrogen source are commercial products with lower price. Therefore, the raw materials of the invention are cheap and easy to obtain, and the invention has commercial advantages.

2) The desulfurization catalyst prepared by the invention has high sulfur selectivity (100-190 ℃ is higher than 99%) and good hydrogen sulfide conversion rate (the metal carbide can be higher than 99% at 160 ℃, and the metal carbide/carbon nitride can be higher than 99% at 190 ℃), so that the sulfur yield is improved (the metal carbide/carbon nitride can be higher than 99% at 190 ℃) and the continuous desulfurization time is long.

Drawings

Figure 1 is an XRD pattern of example 1, example 2, example 3, and carbon nitride.

FIG. 2 is a plot of sulfur yields for example 1 and example 2 and for carbon nitride;

FIG. 3 is a graph of the stability of hydrogen sulfide conversion versus sulfur selectivity for example 1;

FIG. 4 is a graph of example 2 versus carbon nitride hydrogen sulfide conversion;

Detailed Description

The following further illustrates embodiments of the invention: the embodiment is implemented on the premise of the technical scheme of the invention, and a detailed implementation operation process is given, but the protection scope of the invention is not limited by the following embodiment examples. All chemicals were obtained by conventional routes.