Visible-Light-Driven Cleavage of C-O Linkage for Lignin Valorization to Functionalized Aromatics.

Lignin is the most abundant source of renewable aromatics. Catalytic valorization of lignin into functionalized aromatics is attractive but challenging. Photocatalysis is a promising sustainable approach. The strategies for designing well-performing photocatalysts are desired but remain limited. Herein, a facile energy band engineering strategy for promoting the photocatalytic activity of zinc-indium-sulfide (Znm In2 Sm+3 ) for cleavage of the lignol ß-O-4 bond under mild conditions was developed. The energy band structure of Znm In2 Sm+3 could be tuned by controlling the atomic ratio of Zn/In. It was found that Zn4 In2 S7 performed best for cleavage of the ß-O-4 bond under visible-light irradiation, owing to its appropriate energy band structure for offering adequate visible-light absorption and suitable redox capability. Functionalized aromatic monomers with near 18.4 wt % yield could be obtained from organosolv birch lignin. Mechanistic studies revealed that the ß-O-4 bond was efficiently cleaved mainly through a one-step redox-neutral pathway via a Cα radical intermediate. The thiol groups on the surface of Zn4 In2 S7 played a key role in cleavage of the ß-O-4 bond.

Zirconia-supported rhenium oxide as an efficient catalyst for the synthesis of biomass-based adipic acid ester.

Synthesis of adipic acid, a key monomer of nylon-66 and polyurethane, from biomass is highly attractive for establishing green and sustainable chemical processes. Here, we report that zirconia-supported rhenium oxide (ReOx/ZrO2) efficiently catalyses the deoxydehydration of cellulose-derived d-glucaric acid, offering adipic acid ester with a yield of 82% by combining with a Pd/C catalyst in subsequent reactions.

Photoelectrocatalytic reduction of CO2 to syngas over Ag nanoparticle modified p-Si nanowire arrays.

The solar energy-driven reduction of CO2 and H2O to syngas (H2/CO), an important platform to produce chemicals, is of significance for alleviating greenhouse gas emission and utilizing sustainable solar energy. Here, we report a facile method for the photoelectrocatalytic reduction of CO2 and H2O to syngas over an Ag nanoparticle (NP) modified p-Si nanowire array catalyst. The particle size of Ag significantly influences the activity of CO2 reduction to CO. The H2/CO molar ratio in reduction products can be tuned in the range from 1 to 4 by controlling the size of Ag NPs from 4.2 to 16 nm. The adsorption strength of CO on the catalyst was found to decline with the increase in the size of Ag NPs. The Ag NPs of 8.2 nm, which possess a moderate CO adsorption strength, exhibit the maximum production of CO with the H2/CO ratio of 2/1.