Preparation Of MO_x/ZrP Catalyst And Its Catalytic Properties For The Dehydration Of Glycerol To Acrolein

As a solid acid catalyst,zirconium phosphate has the advantage of non-toxic harmless,green and good thermal stability,it is easier to be regenerated activity and separated from product.Besides,the equipment is not required advanced and it is suitable to industrial continuous and automated production.In this thesis,zirconium phosphate was synthesized by the method of precipitation and loaded by different metal oxides in the process of impregnation.The catalytic activity of zirconium phosphate and MOx/ZrP were investigated by the reaction for dehydration of glycerol to acrolein.1.Preparation,characterization and catalytic performance of zirconium phosphatezirconium phosphate was synthesized by the method of precipitation,1M NH4H2PO4 was added dropwise to 1M ZrOCl2 · 8H2O.The catalysts were characterized by thermogravimetric analysis,scanning electron microscope,X-ray diffraction,infrared spectroscopy,NH3 chemical adsorption and N2 physical adsorption etc.The result showed that zirconium phosphate prepared by the precipitation method is amorphous structure composed of irregular particles.NH3-TPD results suggested that the catalyst also have weak acid and medium acid centers.Their catalytic activity was investigated in dehydration of glycerol to acrolein,and the reaction conditions including calcination temperature,reaction temperature,concentration of glycerol,flow rate were evaluated.The results indicated that under the optimal conditions of the calcination temperature was 450?,reaction temperature was 300?,the concentration of glycerol was 40wt%and flow rate was 30 ml/min,the conversion of glycerol and the selectivity of acrolein were up to 91%and 79%respectively.2.Preparation,characterization and catalytic performance of zirconium phosphate modified by single metal componentAlthough the zirconium phosphate catalyst has higher activity in the dehydration of glycerol,there was the room to improve its activity,and the catalyst was easy to be accumulated by carbon in the process of dehydration,so zirconium phosphate is necessary to be modified by the metal oxide.CuO/ZrP?Co3O4/ZrP?NiO/ZrP?FeCO3/ZrP?Nb2O5/ZrP?WO3/ZrP?MoO3/ZrP were prepared by the method of impregnation and characterized by thermogravimetric analysis,scanning electron microscope,X-ray diffraction,infrared spectroscopy,NH3 chemical adsorption etc.The results showed that the metal oxides were loaded evenly on the surface of zirconium phosphate and didn't crystallize,they entered the structure of zirconium phosphate while didn't damage it.Besides,the amount of acid and acidity of medium acid were reduced with the addition of metal oxides.The catalytic activity of zirconium phosphate with different metal oxides was investigated in dehydration of glycerol,the result indicated that zirconium phosphate with 3wt%WO3 showed best catalytic performance,reacted for 12h,the average conversion of glycerol was 90%,and the average selectivity of acrolein was 81%,when load content was 5 wt%,the conversion of glycerol was up to 93%,selectivity of acrolein was 82%.3.Preparation,characterization and catalytic performance of zirconium phosphate modified by two metal componentsCsCl and CeO2 were loaded on WO3/ZrP and MoO3/ZrP to improve the activity of the catalyst and prevent catalysts firom carbon deposition.CsCl/WO3/ZrP?CsCl/MoO3/ZrP?CeO2/MoO3/ZrP?CeO2/WO3/ZrP were synthesized in the process of impregnation and characterized by thermogravimetric analysis,scanning electron microscope,X-ray diffraction,infrared spectroscopy,NH3 chemical adsorption and so on,the results indicated:metal oxides were loaded evenly on the surface of zirconium phosphate while the average pore size increased and specific surface area decreased.Their catalytic activity was surveyed in dehydration of glycerol to acrolein,CeO2/WO3/ZrP showed best catalytic performance,the conversion of glycerol and the selectivity of acrolein were up to 95%and 84%respectively.After regenerating and reusing 6 times,the conversions of glycerol was 85%,and the selectivity of acrolein stayed above 70%.In a word,when calcination temperature was 450 ?,reaction temperature was 300 ?,glycerol concentration was 40wt%,flow rate was 30ml/min,CeO2/WO3/ZrP showed its best catalytic performance,reacted for 12h,the average conversion of glycerol and the selectivity of acrolein were up to 95%and 84%.After regenerating and reusing 6 times,the conversions of glycerol reached 85%,the selectivities of acrolein stayed above 70%,it was expected to be used in industrial production.