Hydrogenolysis of organosolv hydrolyzed lignin over high-dispersion Ni/Al-SBA-15 catalysts for phenolic monomers

Efficiency and recycling of catalysts are important for the lignin hydrogenolysis to obtain phenolic monomers.In this work,a series of highdispersion Ni/AlSBA15 catalysts were prepared by a direct and effective preparation method,and then used in the hydrogenolysis of diphenyl ether(DE)and organosolv hydrolyzed lignin(OHL)for phenolic monomers.The universality of asmade catalysts in different solvents and cyclic performance were investigated.Results showed that the addition of ethylene glycol(EG)during the loading process of Ni promoted the dispersion of metal efficiently.High dispersion of Ni species could highly enhance the conversion of DE and the OHL which Ni/AlSBA15(1EG)exhibited the excellent catalytic performance.Decalin was found to be most effective solvent on the conversion of DE(99.16%).84.77%liquefaction ratio and 21.36%monomer yield were achieved,and no obvious char was observed after the depolymerization of OHL in ethanol solvent at 280℃for 4 h over the Ni/AlSBA15(1EG)catalyst.

Construction of highly dispersed Pt single sites and high-efficiencyheterocatalysis silylation of alcohols with silanes

The construction of silicon-oxygen bonds has been highlighted as an exciting achievement in organosilicon and green chemistry,but their synthetic efficiency has great improvement potential,so it is crucial to explore and achieve an effective approach for synthesizing such compounds.In this study,we successfully prepared the highly dispersed platinum single-atom catalyst(Pt SAC/N-C)through a coordination-assisted strategy with a mixture of ligands(H2bpdc and H2bpydc),which were used for the Osilylation of alcohols with silanes.The strong coordination between Pt2+and the Pyridine N at the skeleton of UiO-67 plays a critical role in accessing the atomically isolated dispersion of Pt sites.Without the assistance of the H2bpydc ligands,the Pt/UiO-67-bpdc precursor is prone to aggregation during the pyrolysis process,resulting in the formation of Pt nanoparticles.Aided by advanced characterization techniques of high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM)and X-ray absorption fine structure(XAFS)spectroscopy,it has been demonstrated that atomically dispersed Pt was formed on the UiO-67 through a local structure of four-coordinated Pt-N4,exhibiting a high actual Pt loading content(0.6962 wt.%).In the oxidation of silanes,the Pt SAC/N-C catalyst showed a high turnover frequency(TOF)value(up to 9,920 h−1)when the catalyst loading decreased to 0.005%.Excellent performance was maintained during recycling experiments,indicating high stability of the catalyst.