Synthesis of glycerol carbonate from glycerol and dimethyl carbonate over the extruded CaO-based catalyst

The extruded CaO-based catalysts are prepared and used for the synthesis of glycerol carbonate from glycerol and dimethyl carbonate. The effects of binders (diatomite, kaolin, and activated alumina), pore-forming agents (polyacrylamide, activated carbon, and polyethylene glycol), and calcination temperatures (700 degrees C, 800 degrees C, and 900 degrees C) on the catalytic activity and stability of the catalyst are investigated. XRD, FT-IR, BET, and SEM are used for the characterization of the prepared catalyst. It is found that the stability of CaO catalyst can be increased by extruding it using activated alumina as the binder and using polyacrylamide, or activated carbon, or polyethylene glycol as the pore forming agent. Under the CaO/binder mass ratio of 3:1, calcination temperature of 800 degrees C, and reaction temperature of 80 degrees C, the glycerol conversion and glycerol carbonate yield for the fresh CaO/Al2O3(polya, 3) catalyst can reach 95.39% and 90.57%, respectively. At the fifth recycling, the glycerol conversion and glycerol carbonate yield for the recovered CaO/Al2O3(polya, 3) catalyst still can reach 65.47% and 62.53%, respectively, which are far higher than for CaO powder catalyst. The extruded catalyst also has a certain water-resistance performance. The catalyst characterization shows the active site of the extruded CaO-based catalyst is CaO. The extruded catalyst not only has higher surface area, higher pore volume, and larger pore diameter, but also higher mechanical strength, and can be used for the industrial process for producing glycerol carbonate. (C) 2013 Elsevier B.V. All rights reserved.