Study On The Mechanism Of Side Reaction In The Process Of CO Coupling Reaction To Dimethyl Oxalate

The mechanism of side reaction in the process of CO coupling reaction to dimethyl oxalate was studied by in situ FT-IR spectroscopy.The primary contents in this paper are as follows:the possibility of NO reduction by CO and the elementary reaction, the influence of H2on the process, thermal and catalytically decomposition of methyl nitrite, and the role of all of those reaction in the process.The main results and conclusions of this paper are as follows:The α-Al2O3supporter was unreactive with CO, however, it can catalyze NO decomposition and generated nitrite, nitrate, which may affect catalyst activity.CO can react with NO on Pd/a-Al2O3catalyst, the reaction of CO oxidation to CO2may be accelerated on chemisorbed oxygen-rich area, and main products ware CO2and N2O under low temperature.H2and linearly adsorbed CO were competitive on catalyst, and H2could promote linearly adsorbed CO transfer to bridgre adsorbed.NO decomposition was promoted by Nad react with Had to form H-Nad, H2-Nad and H3-Nad, and CO oxidation reaction was accelerated for bridge adsorbed CO increased by Had, while N2O selectivity was reduced.MN thermal decomposition occured under high temperature.lt was very slow under low temperature.Catalytical decomposition of MN on Pd/a-Al2O3was very fast, and it begins with N-O bond break and methanol, methyl formate, NO, N2O, CO2were generated by sequential dehydrogenation of methoxy group; methanol and N2O selectivity was increased by H2.CO-NO reaction was very slow for carbonylation reaction was very fast, occupyed most active centres. Carbonylation reaction was sensitive to the ratio of CO/MN, while CO-NO reaction would be accelerated when main reaction slows down.