Catalytic Selective Dehydrogenation Of Guaiacol To Benzene With Different Ru-based Catalysts In Water

The abundant phenolic molecules in the bio-oil make it potential for converting of bio-resource into bio-arenes.In our previous study,Ru based catalysts were proven to be as the effective catalyst for the selective hydrodeoxygenation of guaiacol to benzene in water at conditions of relative high temperatures and low hydrogen pressures.The hydrogenolysis reaction is mainly affected by the nature of metal center,but the fine properties of the selected zeolitic supports may also show effects in catalytic reaction.Therefore,in the thesis we selected guaiacol as reactant and explored the influence of the pore stuctures,acidity,and morphology of support on the selective hydrogenolysis and the reaction rates of guaiacol to benzene in water.The gained some conclusions are listed as follows:1)The pore structures with MFI show the high selectivity to hydrodeoxygenation of guaiacol to benzene,since the diameter of the MFI pores is smaller than the diameter of the reactant molecules,preventing guaiacol entering the pores.In addition,it has been demonstrated that Ru nanoparticles that are located in the pore mouth are more electron-deficient than the Ru nanoparticles on the surface.In that case,Ru located in the pore mouth is much more active than Ru on the surface.The certain distance between the adsorbed reactants and Ru located in the pore mouth is also beneficial to hydrogenolysis reaction.2)The acidity of the HZSM-5 support(including the type of acid and the amount of acid)affects the rate of selective hydrogenolysis of guaiacol.The Br?nsted acid sites of support facilitate for loading the smaller and uniform metal particles.It can enhance the interaction between metal and support,so that the electronic structure of Ru is altered to be more electron-deficient;Whereas Lewis acid site of support can adsorb the reactant,the concentration of adsorbed reactant in support increases.Therefore,the reaction rate is accelerated.In addition,the hydrogenolysis rate of guaiacol will also be accelerated with the increasing total acid content of the catalysts.3)Among three different morphology of HZSM-5(cross-shaped,spherical,cuboid),the largest mesoporous surface area and mesopore pore volume of Ru/HZSM-5(cross-shaped),so it may support relatively uniform and small Ru particles and strong metal-support interaction.Beneficial from the uniform and disperse Ru particles as well as strong metal-support interaction,electron-deficient Ru center together with abundant Lewis acid sites on the cross-shaped HZSM-5 contribute to remarkable hydrogenolysis rates on guaiacol conversion in aqueous phase.