Preparation Of M/TiO₂ Catalysts And Its Performance For The Oxidative Dehydrogenation Of Ethane

Ethylene is a basic chemical raw material that can be synthesized into various industrial necessities.With the continuous development of the catalytic industry and the continuous progress of science and technology,the market demand for ethylene is increasing.The traditional ethylene production method consumes a lot of energy and is complex to operate.The oxidative dehydrogenation of ethane to produce ethylene is not only a method to reduce the costs and difficulties of operation,but also a promising way to solve the problem of the high demand for ethylene.TiO₂ is a low-cost material with weak acidity,and excellent adsorption ability for O₂ and good electronic interaction with transition metal oxides.Therefore,this material was used as a catalyst support in the experiments.It is expected to improve the activities of the catalysts on the premise of maintaining high ethylene selectivities of the catalysts through doping or supporting methods.1.Doped Si-TiO₂ catalysts with different Si:Ti molar ratios were synthesized through a one-step method,and the effects of Si content,reaction temperature,and contact time on the performance of Si-TiO₂ catalysts for ethane oxidative dehydrogenation were studied.The test and characterization results showed that Si was successfully incorporated into the TiO₂ framework,and oxygen vacancies appeared in the lattice due to the strain.These results made the reaction gas more easily adsorbed,thusing improving the catalytic performance of TiO₂ catalyst.At the same time,the incorporation of Si also increased the surface area of the catalysts,and had a certain impact on the distribution of surface species and acid-base properties of the catalysts.At T=600 ^oC,the 5Si-TiO₂ catalyst can achieve 18.8%ethane conversion,64.3%ethylene selectivity,and 11.1%ethylene yield.The 10Si-TiO₂ catalyst can obtain 22.1%ethane conversion,59.2%ethylene selectivity,and 13.1%ethylene yield.2.The supported Co/TiO₂ catalysts were prepared using TiO₂ with high specific surface area as the support using an equivolumetric impregnation method,and the effect of Co loading on the catalytic performance and physicochemical properties of the Co/TiO₂ catalysts were further investigated.The characterization results indicated that the TiO₂ support with high specific surface area significantly improved the dispersion of Co species,and no significant Co aggregation occured in the prepared catalysts.At the same time,the Co loading also changed the surface defect structure of the catalyst and the distribution of oxygen species,which had a certain impact on the catalytic performance of the catalyst.When the mass ratio of Co₃O₄:TiO₂ was 5%and the reaction temperature was 650 ^oC,the catalytic performance of the catalyst was optimal.In this case,the ethane conversion and ethylene yield were 24.4%and 23.1%,respectively.