Synthesis Of YInO₃ Perovskite Catalyst And Study On The Performance In Methane Combustion

With the growing global energy crisis and environmental pollution,nature gas is replacing oil in more and more fields.If the methane that is not fully burned in natural gas is directly released into the atmosphere,it will cause huge greenhouse effect,and ffective measures must be taken.Catalytic combustion technology is currently the most effective way to solve the pollution problem caused by incomplete combustion of natural gas.At present,there are mainly three types of catalysts in methane catalytic combustion:noble metals,perovskite,and hexaaluminate.The perovskite catalyst is favored because of its simple method of synthesis,low cost,good thermal stability,and higher catalytic performance.However,the kinds of perovskite catalysts in methane combustion are too single currently,and the specific surface area of them are generally low,and the main catalytic mechanism in methane combustion is still unclear.Therefore,the research on the synthesis and catalytic mechanism of perovskite catalysts with higher specific surface area has important theoretical and practical significance.In this paper,a perovskite-type YInO3 with high specific surface area was synthesized by glycine self-propagating combustion method,and then applied to the catalytic combustion of methane.The influence of calcination temperature on the crystal structure and catalytic performance of the new catalyst was explored.The catalytic mechanism was studied by the non-stoichiometric doping of A and B sites in YInO3.The main research results are as follows:(1)The cubic phase YInO3 perovskite can be completely formed by the sample precursor after calcination at 650 ?,and the methane catalytic activity of the cubic phase is much better than that of other crystalline phases.Complete conversion of methane can be achieved at 624 ?,and the high activity was still maintained after 50 h continuous reaction.(2)Non-stoichiometric doping of A site can bring more oxygen vacancies to the samples.Y1.04Ifn03+? had much more oxygen vacancies in Yx.InO3+? series samples,and its oxygen desorption amount(759.3 ?amol·g-1)increased by 42%compared with that of the unmodified sample YInO3.The study of CO2-TPD and NH3-TPD showed that the change in quantity of Y3+also had a great influence on the surface acidity and alkalinity of the catalyst,and it had a significant effect on the performance of the catalyst in methane combustion.The catalytic activity of YxInO3+? series samples increased with the increase of Y3+ ion defects,and the best one was Y0,81nO3+? with 626 of T90.(3)There are not many crystal defects in the non-stoichiometric doping at B sites of YlfIy.03+? series samples.The oxygen desorption amount of YIn0,98O3+? with high oxygen vacancy only increased by 7.6%compared with the initial sample(YInO3).NH3-TPD study showed that there was no significant difference in acidity and basicity between YlnyO3+? series samples.The catalytic activity test showed that the In3+ ion at B site is the main catalytic active component of YInO3 perovskite.The catalytic activity of YInyO3+? series samples decreased with the increase of ln3+ ions defect,and the best one was Yln.98 O3+? with 645 0C of T90.(4)The activity of YInO3 perovskite in catalytic combustion of methane is mainly influenced by specific surface area,oxygen vacancy,content of active site and surface acidity,in which the surface acidity and the content of active sites have great influence.