Acetalization Of Glycerol With Acetone To Produce Isopropylidene Glycol Over Zirconia Catalyst

Recently, with the dwindling of oil resource, and the urgent need to save energy and reduce emission, many countries enhance the support in biomass energy development. Over these years, bio-diesel industry has been developed rapidly. Glycerol is the byproduct of biodisel production process. One ton of glycerol is produced with the producing of nine ton of biodiesel. As a result, the global market of glycerol is oversupplied. The market promotion of biodiesel would be restricted by the utilization of glycerol. It favors to reduce cost of biodiesel production and enhance the biodiesel market competitation. Hence, it is desired to develop pathways to produce glycerol to high value product. Glycerol is the simplest triol and could be processed into so many high-value products by oxidation, reduction, halogenation, esterification, or etherification, et al. This investigation focuses on the acetalization of glycerol with acetone to produce isopropylidene glycol over metal oxide catalysts.The investigation started with testing the catalytic activity of a serial of metal oxides to select the best metal oxide catalyst. The influences of catalysts preparation methods and catalyst calcination temperature on catalytic activity were studied. Then, the influences of reaction temperature, molar ratio of acetone to glycerol, and catalyst weight were also investigated. After carrying out the previous investigations, ZrO2-300prepared by calcining of ZrNO3·5H2O was found to show the best catalytic performance under the following conditions:reaction temperature70℃, acetone to glycerol mol ratio10:1and5%wt catalyst (relative to glycerol, same below). Isopropylidene glycol yield of75.6%was reached.The recyclablity and water resistance of ZrO2-300were inspected. After four cycles of application, the catalytic activity decreased very little (the isopropylidene glycol yield decreased about6%). When90%wt glycerol aqueous solution was used as feed stock, the isopropylidene glycol yield reached68.4%. When83.3%wt glycerol aqueous solution used as feed stock, the isopropylidene glycol yield decreased to60.0%.In the sequent work, different zeolites were tested to select the best support for our zirconia catalyst. The influences of loading weight and calcination temperature on catalytic activity were investigated. Under the optimal conditions,85.5%of isopropylidene glycol yield was achieved over10%ZrO2/HZSM5(100)-450. After three cycles of reaction, about7%of decrement in isopropylidene glycol yield was observed. The investigation showed that10%ZrO2/HZSM5(100)-450catalyst had better performance in water resistance than that of ZrO2-300. When83.3%wt glycerol aqueous solution was used as feed stock,74.0%of isopropylidene glycol yield was achieved.The influence of feeding ways on acetalization of glycerol with acetone over ZrO2-300or10%ZrO2/HZSM5(100)-450was investigated. The flow and reaction time were adjusted to maintain the acetone to glycerol molar ratio. At5:1molar ratio of acetone to glycerol, isopropylidene glycol yield could be improved in continuous reaction model. Hence, continuous reaction favors the reaction.Finally, the reaction mechanism was suggested.