| A number of catalysts from transition metals respectively supported on HZSM-5zeolites or other metal oxides were prepared for the conversation of glycerol to pyridine bases.A catalyst from 4.6%of Cu supported on HZSM-5 with Si/Al of 38[4.6%Cu/HZSM-5?38?]was found to perform well in the catalytic reaction.Pyridine bases including pyridine and 2-and 3-picoline,were obtained over this catalyst from glycerol and ammonia.The parameters influencing the catalyst performance were studied thoroughly.An optimized process for the reaction of glycerol with ammonia to the pyridine bases was also obtained.Under the optimized conditions,which include a reaction temperature of 520°C,an atmospheric pressure with an ammonia/glycerol molar ratio of 7:1,and a GHSV of 300h-1,the total carbon yield of the pyridine bases was nearly 42.8%.Characterization results from the IR of the adsorbed pyridine indicated that the doping of copper into HZSM-5?38?led to significant changes in Lewis/Br?nsted acid ratio.An appropriate proportion of the two acids is important to determine the total selectivity of pyridine bases.XRD analysis showed that the copper was initially present in CuO state and then converted into elemental Cu reduced by H2 generated in situ in the catalytic run.TEM and nitrogen adsorption–desorption characterization revealed that the catalyst deactivation was mainly caused by carbonaceous deposits on the catalyst.The catalyst can be regenerated online by blowing air into the reactor at 550°C for 6 h.The slight decrease of the activity of the regenerated 4.6%Cu/HZSM-5?38?compared with that of the fresh one could be ascribed to the partial sintering of copper particles and dealumination of the catalyst in the catalytic run. |
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