Study On The Preparation Of Bifunctional Catalysts And The Catalytic Performance Of Methanol

Catalysts in chemical production,scientific experiments and activities in life,all show their talents,and the catalyst in various types of chemical reactions are playing an irreplaceable role.Methanol is not only an important biological fuel,but also plays an important role in synthetic fabrics,aromatic industries and fuel cells.Methanol can be oxidized to form formaldehyde,methanol,and further condensed into methyl formate(MF),methyl acetal and other important chemical products.The investigation of the oxidation reaction of methanol is the focus of research.The fixed bed was used as an experimental unit for methanol oxidation by gas solid method.The double function is embodied in both the acid center and the oxidation center,and the two functions are concentrated in a catalyst,which brings convenience to the reaction.The oxidation center can select some metal with oxidation property,such as Au,Pt,Rh,Pd and so on.With metal ions in acid,by using mesoporous and macroporous carrier,and the load oxidation center on the carrier,when the reaction gas through the catalyst,acid and oxidation are reflected.In this paper,the carrier of ?-Al2O3,SiO2 and TiO2 were selected preliminarily,and ?-Al2O3 was chosen as the acidic carrier according to the experimental results.The basic experimental conditions such as the amount of the catalyst and the space velocity ratio were investigated,and the optimum conditions were chosen,that is,the mass content of the catalyst was 0.02 g,and the experimental air speed was 20 ml/min and 20 ml/min.On this basis,this paper makes a systematic analysis of Au/?-Al2O3,Pd/?-Al2O3 and AuPd/?-Al2O3 series catalyst,the optimum component of the active component and two-component catalyst dosage proportion optimum ratio,optimization evaluation for methanol oxidation catalytic reaction,has made progress.The conversion of methanol increases with the increase of temperature,and the selectivity of MF increases first and then decreases.Among them,the molar weight of the Au element increased from 2.5 × 10-5 mol to 25 × 10-5 mol,and the mass fraction ranged from 0.49%to 4.9%.When the loading amount is 10 × 10-5 mol,the conversion rate of methanol is 15%,the selectivity of MF is 100%,and the yield of MF is 15%,at 160 ?.The molar loading of Pd in Pd/?-Al2O3 ranged from 2.5 × 10-5 mol to 25 × 10-5 mol,and the mass fraction ranged from 0.27%to 2.66%.When the loading amount is 10×10-5 mol,the conversion rate of methanol is 48%,the selectivity of MF is 60%,and the yield of MF is 29%,at 95 ?.AuPd/?-Al2O3 this series of catalysts,Au and Pd group specific information:?Au 7.5 ×10-5 mol,Pd 2.5 ×10-5 mol,?Au 5.0×10-5 mol,Pd 5.0×10-5 mol,?Au 2.5×10-5 mol,Pd 7.5×10-5 mol and?Au 8.3 ×10-5 mol,Pd 1.7 ×10-5 mol and?Au 1.7 ×10-5 mol,Pd 8.3 ×10-5 mol.The methanol conversion rate was 27%,the MF selectivity was 90%,and the yield of MF was 24%when the temperature was 170 ?.This paper also evaluates the performance of repeated use of AuPd/?-Al2O3 catalyst to be reused for 5 times,the methanol conversion rate of about 25%,the selectivity of MF is about 48%,the yield of MF is about 12%,with the repeated use of the better performance;to explore 5 different blank catalyst,in the temperature range of 100-300 ?,no the catalytic activity,MF generation,indicating that the catalyst can be prepared in this paper have good catalytic performance of methanol.