Preparation Of Titanium Dioxide And Its Composites Supported Noble Metal Catalysts And Study On Hydrogenation Performance Of Biophenols

As one of the main sources of renewable energy and clean energy,biomass has great potential for solving energy crisis and environmental pollution problems.The reaction conditions required for the liquid-phase hydrogenation of biomass phenols are relatively mild,thus saving energy more,and therefore have received extensive attention.However,there are some problems that need to be solved in practical application and research.For example,the use of organic solvents as reaction solvents will damage the environment and cause pollution;the mechanism of the influence of solvents on the hydrogenation of biomass phenols is not clear;the activity of the catalyst in the liquid phase environment and Poor stability and many other issues.To solve the above problems,we first used a method combining experiments and theoretical calculations to study the influence mechanism of different types of solvents on biomass phenols.Secondly,a silica-loaded hollow sphere titanium dioxide supported ruthenium catalyst was designed and successfully prepared,and the mass transfer of the reaction,the number of active sites,and the control of the catalyst's acidity get improved.This paper provides useful practical exploration and theoretical support for further green and effective utilization of biomass resources.The main work is as follows:?1?A method combining experiments and theoretical calculations demonstrate that the adsorption of the solvent at the active site of the catalyst affects the adsorption of the reaction substrate and thus affects the activity.Like polar aprotic solvents?butyrolactone,N,N-dimethylformamide and acetonitrile?and non-polar solvents?1,4-cyclohexanediol and carbon tetrachloride?tightly adsorbed on the palladium atom The surface prevents the reaction substrate from adsorbing at the active site,thereby inhibiting the overall catalytic hydrogenation activity.In contrast,the weakly adsorbed polar protic solvent,such as water and n-hexane do not completely block the adsorption of the reaction substrate at the active site,and thus exhibit high catalytic activity for the hydrogenation of phenol,p-cresol and guaiacol.Solvents also affect selectivity by affecting the adsorption of intermediates.In addition,water shows good catalytic activity in the hydrogenation of biomass phenols,which is mainly attributed to the weak adsorption of water molecules at the active sites.Therefore,for the catalytic conversion of biomass,water is the most reactive solvent.?2?A hollow sphere titanium dioxide supported ruthenium catalyst?Ru-TiO₂-eSiO₂?embedded with silica nanoparticles was prepared for the hydrogenation of guaiacol in the aqueous phase.The results show that the catalyst has better catalytic activity and stability than other catalysts.The relevant characterization shows that its unique structure is the main reason for the catalytic activity,which facilitates mass transport and increases the number of reactive sites.The acidity of the catalyst can effectively increase the removal efficiency of the-OCH₃ functional group,thereby increasing the selectivity of cyclohexanol.