Study On Decarbonylation Of Dimethyl Carbonate To Dimethyl Carbonate By Solid Base Catalyst

Dimethyl carbonate as a raw material of drug active compounds in chemical industry has caused wide attention in recent years, and dimethyl carbonate has a wide range of applications in some areas other than the chemical industry. It is an important raw material of chemical synthesis, and it can replace halogen methane as methylation reagent used in synthesis of pesticides and pharmaceutical intermediates, antioxidants, plastic processing stabilizer etc. it is also a kind of good solvent, has some advantages of good intermiscibility with other organic compounds, the toxicity is very small, has a high evaporation speed and high degrease capacity. At the same time dimethyl carbonate is an important component of the lithium ion battery, in which containing dimethyl carbonate has a high capacitance. It is also a gasoline annexing agent,it has the effect of increase the oxygen content of gasoline, increase the combustion rate and reduce the toxicity of gasoline. Recently there are various kinds of methods for the synthesis of dimethyl carbonate, such as by means of phosgene and methanol, the method of methanol oxidation carbonyl in gas and liquid phase, the oxidation of carbon monoxide and methanol synthesis method, etc. But these methods have significant drawbacks, which may cause environmental pollution or waste of raw materials.Dimethyl oxalate is a downstream product of coal chemical industry, and it’s cheap and easy to gain. Through thermodynamic calculation also indicates that dimethyl oxalate decarbonylation to dimethyl carbonate is feasible. So we choose the method of decarbonylation of dimethyl oxalate to produce dimethyl carbonate.In this paper, a series of alkali metal loaded catalysts prepared with impregnation method, and adopted the pure salts and the combination of different carrier, optimized the preparation conditions and reaction conditions. A series of carriers with different character were selected. By using the interaction of support and catalyst, the product can be efficiently produced under solvent-free condition.This article revolves around the target has carried out the following several aspects:（1） K₂CO₃/AC, Rb₂CO₃/AC, Cs₂CO₃/AC catalysts were prepared through incipient impregnation method. Adjusted the catalysts loading, trying some kinds of calcline temperature based on the carbonate decomposition temperature, regulate the reaction time, rotating speed, reaction temperature and so on. The study found that carbonate catalysts can achieve a high conversion rate in two hours, the selectivity is close to 100%, the order of catalytic activity is: Cs₂CO₃> Rb₂CO₃> K₂CO₃, high load for K₂CO₃ have a greater influence on the catalytic activity, but have little influence on the catalytic activity of Rb₂CO₃ and Cs₂CO₃. So the final choice is low loading, 1.5h, the cacline temperature is 300℃, reaction temper is 220℃, under this condition, the experiment can achieve the best conversion rate and yield.（2） Due to the alkali metal carbonate catalyst which activated carbon as the carrier the stability is not good enough, studied in the reaction activity of various kinds of alkali metal carbonate catalyst which using carbon nanotubes as a carrier. It’s found under the same condition, Rb₂CO₃/CNTs catalyst with low loading can also achieve a high conversion rate, and the selectivity is close to 100%. The catalyst’s activity has declined obviously by used in repeated four times.（3） After the reaction conditions of alkali metal catalysts using carbon nanotubes as carrier for dimethyl oxalate decarbonylation is more mature, tried to use mesoporous carbon prepared by hard template method as a carrier to load alkali carbonate, in order to achieve better conversion rate. The study found that low load Rb₂CO₃/CMK-3 carbon catalyst can get the best conversion rate, and the selectivity is 100%.In this paper, by TEM, XRD and other test means, the morphology of material has carried on the detail analysis and characterization. After experiment, it’s found that carbon carrier used for catalytic dimethyl oxalate decarbonylation to dimethyl carbonate can be showed good catalytic activity, being superior to other carrier.