与现有乙苯直接脱氢工艺技术相比,CO2氧化乙苯脱氢工艺具有缓解直接脱氢热力学平衡限制、苯乙烯选择性高、能耗低和二氧化碳资源化利用等显著优势,有望成为一条从乙苯生产苯乙烯的绿色工艺路线。为此,在总结乙苯直接脱氢反应体系和现有工业技术特点、面临的问题和发展方向的基础上,本文较为全面地分析了CO2氧化乙苯脱氢的特点和反应机理,探讨了现有催化剂体系普遍快速失活的关键原因,表明高性能催化剂研究依然是推进CO2氧化乙苯脱氢工业化应用的关键。鉴于钒基氧化物催化剂表现出较高的活性,成为近年来CO2氧化乙苯脱氢相关研究关注的重点。为此,从钒物种含量及其聚集态结构、催化剂的氧化还原和酸碱性、催化剂表面积炭及其作用等角度,综合分析了活性中心结构、反应机理等方面的相关研究进展,认为孤立态V5+及其含量可能是决定钒基氧化物催化剂活性的关键,其稳定性主要取决于催化剂的氧化还原特性,而积炭对催化剂活性和稳定性的影响则与其组成和石墨化程度密切相关。基于上述认识,认为强化CO2的高效活化、抑制V5+的深度还原等是今后钒基氧化物催化剂研究的重点发展方向,而利用移动固定床或提升管反应器等进行工艺优化,对推进CO2氧化乙苯脱氢工业化应用具有重要的研究价值。The catalytic dehydrogenation of ethylbenzene(EB)to styrene(ST)in the presence of excessive overheated steam(EBDH)is one of the most important industrial processes.However,because of the thermodynamics limitation and the high energy consumption of EBDH,alternative process with more efficiency is continuously pursued.Among the possible alternative routes,the oxidative dehydrogenation of ethylbenzene with carbon dioxide(CO2-ODEB)characterizes the alleviated thermodynamics limitation of EBDH,high ST selectivity,energy-saving,and the efficient utilization of greenhouse gas of carbon dioxide.Moreover,by using carbon dioxide as a soft oxidant,it might open up new directions for oxidation reactions.Thus,CO2-ODEB is intensively investigated as an environmentally benign process.After analyzing the characteristics,problems,and development directions of EBDH in industry,in this review,the characteristics and reaction mechanism of CO2-ODEB and discuss the key reasons for the generally observed rapid deactivation of existing catalyst systems were concentrated on.It indicates that the research of high-performance catalysts is still critical to advance the industrial application of CO2-ODEB.In view of the high activity of vanadium-based oxide catalysts,it has become the research focus on CO2-ODEB in recent years.Therefore,we comprehensively analyzed the relevant research progress on the understanding of the active center structure and reaction mechanisms from the perspectives of the content of vanadium species and its aggregated structure,redox and acid-base properties of catalysts,surface carbon of the catalyst and its functions.It revealed that the isolated state V5+and its content might be the key factors in determining the activity of the vanadium oxide catalyst.Moreover,its stability mainly depends on the oxidation-reduction characteristics of the catalyst.The effect of carbon deposition on the activity and stability of the catalyst is closely related to its composition and graphitization degree.Combining
机构地区陕西省合成气转化重点实验室
出处《化工进展》 EI CAS CSCD 北大核心 2021年第4期1868-1882,共15页Chemical Industry and Engineering Progress
基金国家自然科学基金(21376146,21636006) 中央高校基本科研业务专项(GK201901001)。
关键词催化剂 钒氧化物 二氧化碳 乙苯 氧化脱氢catalysts vanadium oxide carbon dioxide ethylbenzene oxidative dehydrogenation
分类号O643.3 [理学—物理化学]
