Production Of Pyrrole By Gas-Solid Catalysis

Three types of catalysts, ZSM-5, Al2O3, SiO2-Al2O3, were prepared and their catalytic performances for the reaction of furan with ammonia to product pyrrole was studied. The physical properties of catalysts such as specific surface area, pore volume, stacking density and crushing strength were tested. Crystal structure was obtained by XRD. Relative acid strength and acid amount were gotten by NH3-TPD. It is shown that the acid strength of catalysts ZSM-5 is so strong that it reduced the selectivity and catalyst's life. The acid strength of catalyst Al2O3 is too weak to activate the reactants. The catalysts SiO2-Al2O3 have moderate acid strength which give rise to the best performance of synthesizing pyrrole. The temperature of desorption peak of SiO2-Al2O3-d is about at 430℃ and the acid amount of strong acid site about 0.2mol/g resulted in a better catalytic activity, selectivity and fairly long catalyst's life than other catalysts.It is also confirmed that the reaction of producing pyrrole by reaction of furan with ammonia belongs to bimolecular reaction in which the reactants were competitively absorbed on the surface of catalyst prior to the reaction. A suitable ratio of ammonia to furan was about 10 suggested by experiments.The SiO2-Al2O3-d catalyst was modified with different metal nitrates. It indicates that cadmium nitrate and strontium nitrate could improve the catalytic activity obviously.