Carbon Dioxide as a Chemical Building Block and a Reaction Promoter/Controller
作者单位：State Key Laboratory of Electroanalytical Chemistry Jilin Province Key Laboratory of Green Chemistry and Process Changchun Institute of Applied Chemistry Chinese Academy of Sciences
会议名称：《中国化学会·第一届全国二氧化碳资源化利用学术会议》
会议日期：2019年
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学]
关 键 词：carbon dioxide chemical building block carbonate synthesis N-methylation reaction promoter hydrogenation
摘 要：Carbon dioxide is one of unsustainable substances that should be reduced or eliminated in the design, manufacture and use of chemical products. The utilization of CO in synthetic reactions contributes to the design of green sustainable chemical processes and has been investigated so far for several chemical reactions of practical importance. A few examples using CO as a chemical building block will be presented, such as the production of glycerol carbonate from glycerol and urea, in which glycerol is a byproduct in biomass conversion to fuels and urea is produced from CO, and the production of N, N-dimethylaniline via selective N-methylation of N-methylaniline by CO and H. The glycerol carbonate production via urea is one of indirect CO fixation reactions. Those reactions are multiphase reactions using conventional heterogeneous catalysts. In addition to the role of CO as a chemical building brock, it may act as a reaction promoter/controller in liquid phase reactions in spite of its inert nature. Some pressure is required for CO to dissolve into the liquid phases, in which the dissolved CO molecules may interact with reacting species(substrates, intermediates, catalysts), changing their reactivity, and the dissolution of CO assists the dissolution of coexisting gaseous reactants like H and O. The presence of dense phase CO may enhance the reaction rate and control the product selectivity of the liquid phase reactions. A few examples will be presented, including selective hydrogenation of carbonyl, nitro, and nitrile compounds with conventional supported metal catalysts and hydrogen production via photocatalytic water splitting with titanium dioxide powder. In hydrogenation of nitrobenzene, for instance, the desired product of aniline is obtained in 100% selectivity at any conversion level in the presence of CO.