乙炔半加氢催化剂设计

Catalyst Design for Acetylene Semi-Hydrogenation

乙炔半加氢是乙烯纯化最有效的技术之一。钯催化剂由于其优异的性能在工业应用中发挥着主导地位。然而,钯的贵金属性使钯催化剂更加昂贵。设计低价、高选择性、高转化率的乙炔半加氢催化剂具有重要意义。根据乙炔半加氢的加氢机理,从单金属钯基催化剂入手总结了单金属催化剂对乙炔半加氢反应的影响,基于此我们总结出针对乙炔半加氢反应,催化剂的加氢能力过强容易过加氢生成乙烷,加氢能力太弱则选择性和产率太低。当在钯催化剂中加入其他金属时,形成双金属催化剂,可分为典型的取代固溶合金催化剂、金属间化合物催化剂和单原子合金催化剂。对于双金属催化剂对乙炔加氢性能的影响,由于本征结构和催化活性位点的化学环境的不同,除Pd以外的金属对乙炔加氢过程有不同的影响。而催化剂的结构和化学环境最终会影响催化剂活性中心的电子结构。因此我们总结了双金属催化剂对乙炔半加氢反应的影响,着重介绍除Pd金属以外的不同金属加入后,Pd金属活性中心周围环境和电子结构的改变,对乙炔加氢过程不同的影响。我们认为乙炔半加氢的本质是催化剂活性中心的电子结构的变化,电子控制着催化剂的活性中心影响催化剂和H_(2)之间的吸附关系。因此精细调控单个金属活性位点的电子结构,可以提高其对乙炔半加氢催化剂的催化活性、选择性和稳定性。此外,我们提出了高性能乙炔半加氢催化剂的发展方向。未来乙炔半加氢催化剂能够精确控制活性位点,提高其催化活性、选择性和稳定性,是研究人员关注的重点,如精确调控单原子位点、双原子位点和纳米单原子位点催化剂。

Traces of acetylene impurities in the feed gas during the subsequent industrial production process of polyethylene will inactivate ethylene polymerization.The semi-hydrogenation of acetylene to ethylene has been proved to be one of the most effective technologies for the purification of ethylene.Pd catalysts have been playing a leading role in industrial applications due to their excellent performance.However,as Pd is a precious metal,Pd catalysts are expensive.Thus,it is very important to design low-cost,high-selectivity,and high-conversion acetylene semi-hydrogenation catalysts.Here,we summarize the influence of single-metal catalysts based on the acetylene semi-hydrogenation mechanism.The hydrogenation ability of the catalysts should be neither too high nor too low.When other metals are added to palladium catalysts,bimetallic catalysts are formed,which can be classified into typical substitutional solid-solution alloy catalysts,intermetallic compound catalysts,and single-atom alloy catalysts.Regarding the influence of bimetallic catalysts on the performance of acetylene hydrogenation,metals other than Pd have different effects on the acetylene hydrogenation process due to the different structure and environment.While,the structure of the catalyst and the chemical environment ultimately affect the electronic structure of the active center of the catalyst.Based on this,we conclude that the key to the semi-hydrogenation of acetylene is the charge density of the active center of the catalyst,such as dual-atom sites and nano-single atoms;the electrons control the active center of the catalyst.Finely turning the electronic structure of single metal active sites will improve their catalytic activity,selectivity,and stability of the catalyst for acetylene semi-hydrogenation.Additionally,we propose a possible future direction for the development of high-performance acetylene semi-hydrogenation catalysts.Future catalysts for acetylene semi-hydrogenation able to precisely control the active sites to improve their catalytic activity,selectivity,and stability are the focus of researchers,such as the precise control of single-atom-site,dual-atom-site,and nano-single-atom-site catalysts.