CN-118162122-B - Core-shell alumina microsphere catalyst and preparation method thereof, and CF (carbon fiber) catalytic decomposition method4Applications of (2)

CN118162122BCN 118162122 BCN118162122 BCN 118162122BCN-118162122-B

Abstract

The invention discloses a preparation method of a core-shell alumina microsphere catalyst, which comprises the following steps of 1, adding aluminum chloride hexahydrate into a mixed solvent of distilled water and absolute ethyl alcohol, fully stirring the solution according to a certain stirring rate until the solution is completely clarified, keeping the clarified solution in a water bath kettle, 2, adding propylene oxide into the clarified solution to obtain a homogeneous solution, gelling the obtained homogeneous solution in the water bath kettle, 3, soaking an obtained sample in absolute ethyl alcohol after the gelling reaction is finished, 4, transferring the soaked sample into a muffle furnace, calcining the sample at a certain temperature for a certain period of time, and cooling the sample to room temperature to obtain the core-shell alumina microsphere catalyst. The invention also discloses a core-shell alumina microsphere catalyst and application thereof in the catalytic decomposition of CF 4 . The invention solves the problem of low efficiency of treating CF 4 gas by a catalytic hydrolysis method at present.

Inventors

LIU MIN
ZHENG JIALIN
WANG XIAOJIAN
ZHANG XING
FU JUNWEI
LIU KANG

Assignees

中南大学

Dates

Publication Date: 20260505
Application Date: 20240329

Claims (5)

1. The preparation method of the core-shell alumina microsphere catalyst is characterized by comprising the following steps of: Step 1, adding aluminum chloride hexahydrate into a mixed solvent of distilled water and absolute ethyl alcohol, fully stirring the mixture according to a certain stirring rate until the solution is completely clarified, and keeping the obtained clarified solution in a water bath kettle; Step 2, adding propylene oxide into the clear solution to obtain a homogeneous solution, and gelatinizing the obtained homogeneous solution in a water bath; Step 3, after the gelation reaction is finished, soaking the obtained sample in absolute ethyl alcohol; Step 4, transferring the soaked sample to a muffle furnace, calcining for a period of time at a certain temperature, and cooling to room temperature to obtain the core-shell alumina microsphere catalyst; The temperature of the water bath kettle in the step 1 is 50-70 ℃, the stirring speed is 150-300 r/min, the proportion of the aluminum chloride hexahydrate in the distilled water and absolute ethyl alcohol mixed solution in the step 1 is 0.4-0.58 g/mL, and the volume ratio of the distilled water to the absolute ethyl alcohol is 0.6-0.8; The temperature of the water bath kettle in the step 2 is 50-70 ℃, and the molar ratio of the epoxypropane to the aluminum chloride hexahydrate added in the step 1 is (4-4.5): 1; The soaking time of the absolute ethyl alcohol in the step 3 is 12-36 hours, and the absolute ethyl alcohol is replaced every 2-6 hours in the soaking process; and in the step 4, the calcination temperature is 750-850 ℃, the calcination time is 1-3h, and the temperature rising rate of the muffle furnace during calcination is 2-4 ℃ per minute.
2. A core-shell alumina microsphere catalyst prepared according to the preparation method of claim 1.
3. The core-shell alumina microsphere catalyst according to claim 2, wherein the core-shell alumina microsphere catalyst has a round shell structure formed by stacking alumina nano sheets on the outside and alumina pellets on the inside.
4. Use of a core-shell alumina microsphere catalyst according to claim 2 or 3 for the catalytic decomposition of CF 4 .
5. The use according to claim 4, wherein the specific process is: step 1, filling a core-shell alumina microsphere catalyst into a quartz tube, and filling the quartz tube into a reaction bin of a fixed bed; Step 2, pre-introducing mixed gas of CF 4 and air into a reaction chamber by a gas circuit system, wherein the volume concentration of CF 4 is 0.2-0.5%, the volume concentration of air is 99.5-99.8%, the flow rate of the mixed gas is 28.3-38.3 mL/min, heating the reaction chamber of the fixed bed to 550-650 ℃ after the gas circuit is stable, the heating rate is 10-15 ℃ per min, introducing water into a vaporization chamber by an injection pump, the water inlet rate is 0.6-0.8 mL/h, heating the vaporization chamber, the heating temperature of the vaporization chamber is 180-220 ℃, and introducing water vapor generated by the vaporization chamber into the reaction chamber; and 3, the tail gas obtained from the reaction bin is firstly dried by a deionized water bottle and then a drying pipe, and the dried gas enters a gas chromatograph to detect the components and the content of the gas.

Description

Core-shell alumina microsphere catalyst, preparation method thereof and application thereof in catalytic decomposition of CF 4 Technical Field The invention belongs to the technical field of catalyst preparation, and particularly relates to a core-shell alumina microsphere catalyst, a preparation method thereof and application thereof in catalytic decomposition of CF 4. Background CF 4 is considered to be the most abundant, most hazardous one of the perfluorinated compounds, with a higher global warming potential, about 4 orders of magnitude higher than carbon dioxide-with very long atmospheric lifetimes (3000-50000 years). At present, CF 4 has been included in an important greenhouse gas abatement line, and thus it is necessary to decompose the perfluorocarbon exhaust gas produced by an industrial process. CF 4 has a bond energy up to 543±4kJmol -1 due to its highly symmetrical single carbon structure, which makes it difficult to decompose. Catalytic hydrolysis is considered the most effective technique for decomposing CF 4 because of its high decomposition rate under mild conditions and the low amount of harmful chemicals involved. However, the efficiency of catalytic hydrolysis of CF 4 is low, and there is a need to develop a high-efficiency catalyst that improves the efficiency of catalytic hydrolysis of CF 4 to solve this problem. Disclosure of Invention The embodiment of the invention aims to provide a core-shell alumina microsphere catalyst, a preparation method thereof and application thereof in catalytic decomposition of CF 4, so as to solve the problem of low efficiency of treating CF 4 gas by a catalytic hydrolysis method at present. In order to solve the technical problems, the invention adopts the technical scheme that the preparation method of the core-shell alumina microsphere catalyst comprises the following steps: Step 1, adding aluminum chloride hexahydrate into a mixed solvent of distilled water and absolute ethyl alcohol, fully stirring the mixture according to a certain stirring rate until the solution is completely clarified, and keeping the obtained clarified solution in a water bath kettle; step 2, adding propylene oxide into the clear solution to obtain a homogeneous solution, and gelatinizing the obtained homogeneous solution in a water bath; Step 3, after the gelation reaction is finished, soaking the obtained sample in absolute ethyl alcohol; And 4, transferring the soaked sample to a muffle furnace, calcining for a period of time at a certain temperature, and cooling to room temperature to obtain the core-shell alumina microsphere catalyst. Further, the temperature of the water bath kettle in the step 1 is 50-70 ℃, and the stirring speed is 150-300 r/min. Further, in the step 1, the proportion of the aluminum chloride hexahydrate in the mixed solution of the distilled water and the absolute ethyl alcohol is 0.4-0.58 g/ml, and the volume ratio of the distilled water to the absolute ethyl alcohol is 0.6-0.8. Further, the temperature of the water bath kettle in the step 2 is 50-70 ℃, and the molar ratio of the propylene oxide to the aluminum chloride hexahydrate added in the step 1 is (4-4.5): 1. Further, in the step 3, the soaking time of the absolute ethyl alcohol is 12-36 hours, and the absolute ethyl alcohol is replaced every 2-6 hours in the soaking process. Further, in the step 4, the calcination temperature is 750-850 ℃, the calcination time is 1-3 h, and the temperature rising rate of the muffle furnace during calcination is 2-4 ℃ per minute. The invention also provides a core-shell alumina microsphere catalyst, which is prepared by the preparation method. Further, the core-shell alumina microsphere catalyst has a round shell structure formed by stacking alumina nano sheets outside and alumina pellets inside. The invention also provides application of the core-shell alumina microsphere catalyst in catalytic decomposition of CF 4. The specific process is as follows: step 1, filling a core-shell alumina microsphere catalyst into a quartz tube, and filling the quartz tube into a reaction bin of a fixed bed; Step 2, pre-introducing mixed gas of CF 4 and air into a reaction chamber by a gas circuit system, wherein the volume concentration of CF 4 is 0.2-0.5%, the volume concentration of air is 99.5-99.8%, the flow rate of the mixed gas is 28.3-38.3 ml/min, after the gas circuit is stable, heating the reaction chamber of the fixed bed to 550-650 ℃ with the heating rate of 10-15 ℃ per min, introducing water into a vaporization chamber by an injection pump with the water inlet rate of 0.6-0.8 ml/h, heating the vaporization chamber, the heating temperature of the vaporization chamber is 180-220 ℃, and introducing water vapor generated by the vaporization chamber into the reaction chamber; and 3, the tail gas obtained from the reaction bin is firstly dried by a deionized water bottle and then a drying pipe, and the dried gas enters a gas chromatograph to detect the components and the