钴锰比对CoMnNa催化剂费-托合成催化性能的影响  

Effect of cobalt-manganese ratio on the Fischer-Tropsch synthesis performance of CoMnNa catalysts

作　　者：伍清森 吕帅[1] 张煜华[1] 王立[1] 李金林[1] WU Qing-sen;LYU Shuai;ZHANG Yu-hua;WANG Li;LI Jin-lin(Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education&Hubei Key Laboratory of Catalysis and Materials Science,South-Central University for Nationalities,Wuhan 430074,China)

机构地区：[1]中南民族大学,催化转化与能源材料化学教育部重点实验室暨催化材料科学湖北省重点实验室,湖北武汉430074

出　　处：《分子科学学报》2021年第3期222-229,共8页Journal of Molecular Science

基　　金：国家自然科学基金资助项目(22072184,21972170)。

摘　　要：利用热分解法制备了一系列钴锰比例不同、粒径均一的CoMn纳米晶,基于此结构明确的催化材料,考察了钴锰比例对催化剂的费-托合成活性与产物选择性的影响.研究结果表明,随着Mn含量的增加,催化剂还原性降低,随着钴锰比例由1∶1增加到5∶1,费-托合成产物的α值(链增长概率)由0.39增加到了0.59.低碳烯烃选择性由66.5%降低到了51%.反应后的催化剂的X射线衍射表征结果以及原位漫反射红外光谱表征结果表明,反应过程中可能同时存在Co2C与金属Co活性相.钴锰比例影响产物选择性的原因可能是Mn含量影响了反应过程中Co2C与Co活性相的比例.Light olefins are carbon-based building blocks with important uses in the manufacture of polymers,drugs,and a broad range of fine chemicals.They are usually produced via naphtha cracking or fluid catalytic cracking.Due to growing demands for light olefins and dwindling petroleum supplies,selective methods or transformations of other carbon feedstocks into olefins are urgently required.Fischer-Tropsch to olefins(FTO)has been proposed as a promising route by which coal,natural gas,and biomass can be converted to promoted olefins via the catalyzing syngas conversion.However,the traditional Fischer-Tropsch synthesis generates products with a distribution that follows a theoretical restriction,suffering from low selectivity toward desired products.Recently,Zhong et al.reported that CoMn oxides promoted with Na exhibit promising light olefin selectivity over syngas conversion,with a CH4 selectivity around 5%,and the O/P ratio(olefin/paraffin ratio)of light olefins products as high as 51,which denotes significant progress in the development of novel FTO catalysts.Clarifying the structure-activity relationship of CoMnNa catalysts could guide the optimization of catalyst structure effectively.Nevertheless,CoMnNa catalysts are very complex in chemical composition,and complex phase transitions during activation and reaction are even great challenge for researches.The study of structure-activity relationship of catalyst depends highly on the design and synthesis of well-defined model catalyst.After development for nearly thirty years,thermal decomposition has become one of the most mature and reliable approach to control the crystallographic form,particle size,morphology and chemical constituents of nanomaterials accurately.Herein,a series of nano-alloys with different Co/Mn ratio and uniform particle size were prepared by thermal decomposition method.Based on these well-defined catalytic materials,the influence of Co/Mn ratio on catalytic performance of CoMnNa catalyst was studied.With the increased of Mn content,the reduci

关 键 词：费-托合成 CoMnNa催化剂 纳米晶 低碳烯烃 碳化钴 

分 类 号：O611[理学—无机化学]