Pt、Cu共改性TiO2选择性光催化还原CO2制CH4  

Selective photocatalytic reduction of CO2 into CH4 by Pt and Cu co-modified TiO2

作　　者：李长华 赵江婷 熊卓[2] 赵永椿[2] LI Changhua;ZHAO Jiangting;XIONG Zhuo;ZHAO Yongchun(National Energy Group Jiangxi Power Generation Corporation,Fengcheng 331100,China;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]国家能源集团江西发电有限公司,江西丰城331100 [2]华中科技大学煤燃烧国家重点实验室,湖北武汉430074

出　　处：《洁净煤技术》2020年第4期162-167,共6页Clean Coal Technology

基　　金：国家自然科学基金资助项目(51706082,U1610110)。

摘　　要：光催化还原CO2是具有前景的可再生能源技术,但由于光生电子-空穴对的快速复合和对可见光的有限利用,TiO2表现出较低的光催化反应效率,为了提高TiO2光催化还原CO2的效率,用金属改性TiO2是一种有效的方式。笔者通过化学还原法将Pt和Cu2O纳米颗粒沉积在锐钛矿TiO2晶体表面,系统研究了Pt、Cu共改性对TiO2光催化还原CO2性能的影响。光催化试验结果表明,Pt沉积有利于生成CH4和H2,而Cu2O会抑制H 2的生成,且对CH4的选择性低于Pt。Pt和Cu2O同时沉积在TiO2晶体上时,H2的生成受到抑制,CO2被选择性地还原为CH4,选择性达96.6%。催化剂表征结果表明,Pt能捕获光生电子,从而提高催化剂上的电子密度,有利于多电子还原反应发生,高选择性地生成CH4。Cu2O提高了催化剂对CO2的化学吸附能力,同时对水的吸附能力较弱,从而抑制H 2的生成,提高了光生电子对CO2还原的选择性。此外,反应后的Pt-Cu/TiO2中Cu2O几乎被完全还原为Cu,这可能是由于在光催化反应过程中,Pt沉积可促进光生电子向Cu2O迁移,在Cu2O还原为Cu的同时为光催化还原反应提供更多的电子,有利于CH4的选择性生成。因此,Pt-Cu/TiO2催化剂可将CO2选择性地还原为CH4。经3次循环试验,催化剂的活性未降低,具有良好的稳定性。Photocatalytic reduction of CO2 is a challenging renewable energy production technology.However,due to the rapid recombination of photogenerated electron hole pairs and the limited utilization of visible light,TiO2 shows low photocatalytic reaction efficiency.In order to improve the efficiency of photocatalytic reduction of CO2 by TiO2,it is an effective way to modify TiO2 by metal.In this paper,Pt and Cu2O nanoparticles were co-deposited on the surface of TiO2 nanocrystals by chemical reduction method.The influence of Pt and Cu co-modification on the photocatalytic reduction of CO2 by TiO2 was systematically studied.The experimental results show that Pt deposition tends to promote the production of CH4 and H2.However,Cu2O can suppress H2 production and exhibites lower CH4 selectivity than that of Pt.Furthermore,after co-deposition of Pt and Cu2O on TiO2 crystal,the formation of H2 is inhibited,and CO2 is selectively converted to CH4,with a selectivity of 96.6%.The characterization experiments and a series of photocatalytic reduction selectivity experiments show that Pt can not only capture the photogenerated electrons,but also improve the electron density on the catalyst,which is conducive to the multi-electron reduction reaction and the formation of CH4 with high selectivity.Cu2O enhances the chemical adsorption of CO2 on TiO2 and inhibites the adsorption of water,thus the formation of H 2 is inhibited and the selectivity of photogenerated electrons for CO2 reduction is improved.In addition,Cu2O in Pt-Cu/TiO2 after the reaction is almost completely reduced to Cu,which may be caused by the process of photocatalytic reaction,Pt deposition can promote the transfer of photogenerated electrons to Cu2O.This phenomenon can provide more electrons for the photocatalytic reduction while reducing Cu2O to zero valent Cu,which is conducive to the selective generation of CH4.Therefore,Pt-Cu/TiO2 catalyst can selectively reduce CO2 to CH4.After three cycles of tests,the activity of the catalyst is not reduced and has good sta

关 键 词：CO2光催化还原 TiO2 选择性 共沉积 CH4 

分 类 号：TQ53[化学工程—煤化学工程] TK114[动力工程及工程热物理—热能工程]