Study On A Novel Catalyst For Methane Conversion

In recent years,with the development and utilization of unconventional natural gas resources,the reserves of natural gas have increased substantially worldwide.How to achieve the efficient use of natural gas has become a research focus widely concerned by academia and industry.As the main component of natural gas,methane can be converted into liquid fuel and basic chemicals through catalytic reactions.There are two main ways of methane conversion:indirect conversion and direct conversion.Among them,the direct conversion technology of methane has important research significance because it meets the development requirements of green chemistry,which can effectively improve the atomic utilization rate of methane,and the energy consumption is relatively low.This paper synthesizes a series of catalysts for low-temperature methane conversion reaction,so that it can achieve efficient conversion of methane into high value-added chemical products at atmospheric pressure and temperature range of 500℃～600℃,and optimize the catalyst performance by changing the reaction conditions.The active metal that can easily activate methane is supported on the carrier Fe2O3 by excessive impregnation,and then it is mechanically mixed with Mo/HZSM-5 molecular sieve catalyst with excellent aromatization performance at a certain ratio and applied to the methane conversion reaction at low temperature.First,the effect of Pt/Fe2O3+Mo/HZSM-5 mixed catalyst on the catalytic performance of methane conversion at low temperature was investigated.The reaction performance of the catalyst is optimized by adjusting the loading of the active metal on the carrier,the mixing ratio of the two catalysts,the reducing gas atmosphere and other conditions.The experimental results show that under the reduction of hydrogen atmosphere,when Pt loading and Mo loading respectively are 3 wt.%and 6 wt.%,the mechanical mixing of 3Pt/Fe2O3-6Mo/HZSM-5 according to the mass ratio of 1:5,the catalytic performance of the catalyst is better.At the end of the reaction,the conversion rate of methane is 2.35%,the total selectivity of the aromatic product produced is as high as 83%,and the selectivity of benzene is 61%.Adding additives to the feed gas can slow down the downward trend of methane conversion rate and extend the service life of the catalyst.Secondly,the catalytic performance of the catalyst prepared by mechanically mixing the Pd/Fe2O3 catalyst with the Mo/HZSM-5 molecular sieve catalyst to methane conversion at low temperature was investigated.The catalyst performance is optimized by adjusting the loading of Pd and changing the reduction time of the catalyst.The results show that the 1Pd/Fe2O3-6Mo/HZSM-5 catalyst with a Pd loading of 1 wt.%and mechanical mixing at a mass ratio of 1:5 has a high selectivity for aromatic products,and the reduction time is 1 h,The highest selectivity to product benzene,up to 64%,when the reduction time is 3 h,the highest selectivity to product C10 is 67%.Finally,the catalytic performance of the catalyst prepared after the mechanical mixing of the Ni/Fe2O3 catalyst and the Mo/HZSM-5 molecular sieve catalyst in the methane conversion reaction at low temperature was investigated.By changing the mechanical mixing ratio of the two catalysts,adjusting the space velocity and reduction gas atmosphere during the reaction to optimize its performance for this reaction.The experimental results show that the 5Ni/Fe2O3-6Mo/HZSM-5 catalyst,which is mechanically mixed according to the mass ratio of 1:5,reduced at the hydrogen atmosphere and the reaction space velocity is 15000 ml/gcat·h has the best catalytic performance.After the end,the conversion rate of methane is 1.5%,and the selectivity of the produced aromatic product is 79%,with the selectivity of benzene is 70%.