调控Ru的电子态以促进乙烯在酸中高选择性电氧化合成乙二醇  

Manipulating the electronic state of ruthenium to boost highly selective electrooxidation of ethylene to ethylene glycol in acid

作　　者：王杰 陈怡和 王宇达 赵浩 叶进裕 程庆庆 杨辉 Jie Wang;Yihe Chen;Yuda Wang;Hao Zhao;Jinyu Ye;Qingqing Cheng;Hui Yang(School of Physical Science and Technology,Shanghai Tech University,Shanghai 201210,China;Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201210,China;College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,Fujian,China)

机构地区：[1]上海科技大学物质科学与技术学院,上海201210 [2]中国科学院上海高等研究院,上海201210 [3]厦门大学化学化工学院,福建厦门361005

出　　处：《Chinese Journal of Catalysis》2024年第5期376-385,共10页催化学报（英文）

基　　金：国家重点研发计划(2021YFB4000200);上海市自然科学基金面上项目(23ZR1471000).

摘　　要：乙二醇(EG)是一种重要的化工产品,由于在化学品制造行业的广泛应用而备受关注.然而,目前工业上制备乙二醇主要采用乙烯作为原料,经过环氧化和水解两步反应,这一过程不仅需要高温高压,还需使用成本高的氧化剂(如H_(2)O_(2)),这违背了绿色化学的原则.因此,电催化阳极氧化作为一种新兴的合成策略,正逐渐受到研究者的青睐.该技术仅通过电子转移并利用水作为氧源,就能够高效合成高附加值含氧化学品.特别是,阳极氧化反应可与阴极还原反应(例如氢析出反应)相耦合,实现能量的高效利用.尽管电催化阳极氧化具有诸多优势,但目前在乙烯电氧化合成乙二醇过程中,其选择性仍然较低,这导致后续的纯化过程变得复杂且成本高昂.因此,开发高选择性的电氧化合成乙二醇技术,成为了一项迫切且极具挑战性的任务.本文提出了一种Ir和Ru合金化策略,以提高乙烯电氧化制备乙二醇的选择性和耐久性.研究结果表明,当Ir和Ru的原子比达到适当的比例(即Ir_(0.54)Ru_(0.46))时,所制备的IrRu合金表现出近100%的乙二醇选择性,远远优于Ru NPs对照组样品(43.8%).此外,在1.475 V的电压下,Ir_(0.54)Ru_(0.46)催化生成乙二醇产率达到了60.62 mmolgRu^(-1) h^(-1),是Ru NPs上最高产率(21.75 mmolgRu^(-1) h^(-1))的2.8倍.在耐久性测试中,Ir_(0.54)Ru_(0.46)能够稳定催化生成乙二醇超过12 h,其生成速率为6μmol L^(-1) h^(-1).相比之下,对照组样品Ru NPs在电解反应3 h后已失去活性.能量损失谱分析显示,Ir_(0.54)Ru_(0.46)在电解2 h后形成了稳定的表面富Ir核壳结构IrRu@Ir,这是催化剂稳定性提升的关键.先进光谱研究进一步揭示,Ir的引入导致了电子由Ru位点向Ir流动,使Ru位点带正电荷,从而减弱了OH的吸附.OH脱附实验结果表明,随着Ir/Ru原子比的增加,OH更容易从Ru位点脱附,这促进了OH与乙烯的偶联反应.自由基淬灭和氘代同位素标记实�Electrochemical oxidation of ethylene is a novel approach to manufacture valuable ethylene glycol(EG),which is an important raw material in organic chemical industry.However,the poor EG selectivity and expensive additional purification costs hinder this method from being practically used.In this work,ultrafine iridium-ruthenium(IrRu)alloy nanoparticles are synthesized through the precipitation-reduction method and their electrocatalytic performance towards ethylene oxidation to EG has been comprehensively studied.Near 100%selectivity is achieved with a EG yield of 60.62 mmol gRu^(-1) h^(-1) at 1.475 V on an optimal Ir_(0.54)Ru_(0.46) catalyst.OH-stripping,in‐situ electrochemical attenuated total internal reflectance Fourier transform infrared spectra and DFT calculation reveal that the introduction of Ir can modulate the electronic structure and d-band center so as to endow the Ru with the mild binding energy with the key intermediates and small energy barrier for*HOCH_(2)CH_(2)OH desorption,thereby enhancing the EG generation.Simultaneously,the high energy barrier for the overoxidation of the*CH_(2)CH_(2)OH renders the EG formation thermodynamically favorable,thus realizing the near 100%EG selectivity.This work provides a new understanding for the high-selectivity electrosynthesis of high-value-added oxides.

关 键 词：乙烯电氧化 电合成乙二醇 高选择性 IrRu合金 电子结构 

分 类 号：TQ223.162[化学工程—有机化工] TQ426