Ga-O双功能位点促进高选择性光催化甲烷直接转化制甲醇  

Promotion of highly selective photocatalytic conversion of methane into methanol by Ga-O bifunctional sites

作　　者：韩春秋 曹玥晗 邱杰[2] 马敏智 董帆 周莹[1,2] Chunqiu Han;Yuehan Cao;Jie Qiu;Minzhi Ma;Fan Dong;Ying Zhou(National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;School of New Energy and Materials,Southwest Petroleum University,Chengdu 610500,China;Research Center for Environmental Science and Technology,Institute of Fundamental and Frontier Sciences,University of Electronic Science and Technology of China,Chengdu 611731,China)

机构地区：[1]西南石油大学,油气藏地质及开发工程全国重点实验室,成都610500 [2]西南石油大学新能源与材料学院,成都610500 [3]电子科技大学基础与前沿研究院,环境科学与技术研究中心,成都611731

出　　处：《科学通报》2023年第33期4544-4555,共12页Chinese Science Bulletin

基　　金：国家自然科学基金(22209135,22209136);中央引导地方科技发展资金(22ZYZYTS0231);四川省自然科学基金(2022NSFSC1264);中国博士后科学基金(2022M722635);四川省博士后创新人才支持项目;西南石油大学研究生科研创新基金(2020CXZD16)资助。

摘　　要：光催化甲烷(CH_(4))直接转化制甲醇(CH_(3)OH)被誉为催化界的“圣杯反应”.然而,由于反应过程中目标产物容易发生过氧化反应,实现CH_(3)OH的定向转化仍然面临巨大挑战.本文通过溶剂热法和高温煅烧法成功地制备了不同晶相的Ga_(2)O_(3)光催化材料(α-Ga_(2)O_(3)和β-Ga_(2)O_(3)),并对其光催化CH_(4)直接转化制CH_(3)OH的性能进行评价.测试结果显示在室温常压,且不额外添加其他氧化剂的情况下,α-Ga_(2)O_(3)和β-Ga_(2)O_(3)表现出优异的光催化性能.相较于β-Ga_(2)O_(3),α-Ga_(2)O_(3)的光催化性能更优:反应2 h后,其CH_(4)转化率达4.5%,CH_(3)OH的生成速率与选择性分别高达372.8μmol/(g h)和82.7%.通过原位红外光谱(in situ DRIFTS)和原位电子自旋共振谱(in situ EPR)对反应机理进行了分析,发现Ga_(2)O_(3)的Ga和O分别是活化CH_(4)和水分子(H_(2)O)的活性位点.得益于Ga-O双功能活性位点的协同作用,CH_(4)和H_(2)O活化产生的·CH_(3)和·OH可以直接结合,促进了CH_(3)OH的定向生成.由于α-Ga_(2)O_(3)比β-Ga_(2)O_(3)展现出更强的活化H_(2)O的能力,α-Ga_(2)O_(3)表现出更优异的光催化CH_(4)直接转化制CH_(3)OH性能.本文为设计高效的CH_(4)直接转化制CH_(3)OH催化材料打开了新的思路.Methane(CH_(4)),the principal constituent of natural and shale gasses,possesses substantial global reserves.It is widely acknowledged that CH_(4),a prevalent fossil fuel,releases significant quantities of carbon dioxide upon combustion.Notably,methane assumes significance not only as a vital fossil fuel but also as a crucial precursor for synthesizing valuable chemicals.The oxidation of CH_(4) to yield high-value chemicals exhibits promising prospects for future development.Methanol(CH_(3)OH)is widely regarded as an optimal product for CH_(4) conversion in high-value chemicals,owing to its advantageous properties as a liquid chemical,facilitating convenient storage and transportation.Currently employed in industrial settings,methanol synthesis from methane involves an indirect approach.Initially,CH_(4) is converted into syngas(CO and H_(2))under high temperature and pressure conditions.Subsequently,this syngas undergoes Fischer-Tropsch synthesis to yield methanol.The present method is characterized by a complex process flow,high energy consumption,and elevated reaction costs,which pose significant barriers to sustainable development and implementation.Therefore,developing low-energy consumption and low-cost methods to achieve selective oxidation of CH_(4) to CH_(3)OH under mild conditions is essential.In recent years,photocatalytic technology has realized direct conversion of CH_(4) to CH_(3)OH under mild conditions.However,due to the tendency of the target product,CH_(3)OH,to undergo peroxide reactions,the selectivity is usually relatively low.Selective photocatalytic direct conversion of CH_(4) to CH_(3)OH is considered a“holy grail”reaction in the field of catalysis.In this work,we successfully synthesized Ga_(2)O_(3) photocatalytic materials with distinct crystal phases(α-Ga_(2)O_(3) and β-Ga_(2)O_(3))through solvothermal and calcination processes at high temperatures.Subsequently,their photocatalytic performance in the oxidation of CH_(4) to CH_(3)OH was evaluated.The experimental results highlight tha

关 键 词：甲烷转化 光催化 甲醇选择性 Ga-O双功能位点 氧化镓 

分 类 号：TQ223.121[化学工程—有机化工] TQ426[环境科学与工程—环境工程] X701