| Methanol is an important carbon-chemical raw material and can be used to prepare methyl formate,an important organic intermediate.Gas-phase methanol catalysis is simpler than traditional methods and is one of the ways to develop the methanol industry.In order to improve the gas phase methanol oxidation process,catalysts such as Au/?-Al2O3,Pd/?-Al2O3 and(Au-Pd)/?-Al2O3 were prepared.The structure of the catalyst was characterized by XPS,XRD and BET.The performance of methanol-catalyzed oxidation in the gas phase was evaluated on a miniature fixed-bed reactor.Some of the major experimental results were as follows:(1)By characterization,the Au and Pd metals are successfully supported on ?-Al2O3,the particles of the catalytic components are uniformly dispersed,and the grain size is basically the same,but there are unreduced metal ions in the ?-Al2O3,and the metal ions are mainly dispersed.On the surface of?-Al2O3.The optimal air flow rate for oxygen and nitrogen is 20 mL/min,and the optimum amount of catalyst used is 20.00 mg.(2)In the single-component Au/?-Al2O3 and Pd/?-Al2O3 catalysts,the optimal catalyst performance is obtained when the loadings of gold and palladium are 1.97wt%and 1.06wt%,respectively.For Au/?-Al2O3 catalysts with monometallic Au,the maximum yield at 170? was 16.45%.At this time,the conversion of methanol was 19.56%and the selectivity of methyl formate was 97.50%.For a single metal Pd/y-Al2O3 catalyst,when the Pd loading was 1.06 wt%,the maximum yield at 170? was 28.96%and the selectivity was 99.82%.(3)In the bimetallic AuPd/y-Al2O3 catalyst,the optimal molar ratio of Au to Pd is 3:1,160?,the conversion of methanol is 23.89%,the selectivity of methyl formate is 96.10%,yield reached 29.96%.The maximum conversion,selectivity and yield from bimetallic catalysts are higher than that of single metal catalysts,so the use of gold-palladium bimetallic catalysts for catalytic gas-phase methanol oxidation has the best effect. |
PDF Full Text Request