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The N-formylation of amines with CO2 and hydrosilanes is an emerging yet important reaction in fine chemical industry. Herein, we have reported a methyltrioctylammonium cation (TOMA) stabilized Nb oxocluster catalyst that can effectively realize two electron reduction of CO2 and form C-N bond simultaneously, leading to the corresponding formamides. The oxocluster catalyst exhibits excellent catalytic activity to transform secondary and primary amines into the corresponding formamides, with the conversion ranging from 81.5% to 99.2% under room temperature conditions. Furthermore, the Nb oxocluster catalyst shows the unique characteristics of ionic liquids, and it is highly robust and easy to be recycled for five times with negligible loss of catalytic activity. On the basis of the activity tests and structure characterization of Nb catalysts, it was found that TOMA cation played an important role in modulating the Nb oxocluster with high stability and uniform dispersion. The mechanism studies demonstrate that the formylation reaction proceeds through the formation of silyl formate intermediate rather than carbamate, and the Lewis base site of negative oxygen atoms from polyoxoniobate anions can exert a favorable impact on activation both CO2 and Si-H bond of PhSiH3, allowing that N-formylation reaction proceed smoothly under very mild reaction conditions.

The shortage of resources and the destruction of the environment have caused serious resource and environmental problems shared by all countries around the world. As a ubiquitous renewable resource, biomass has great prospects for replacing fossil energy and attracted attention from the society. The use of catalytic approach to transform biomass into high-value chemicals is an effective way to use biomass efficiently. In this work, Ni-supported catalysts has been developed for the selective cleavage of C–O bonds in lignin model compounds with 2-propanol as the hydrogen source solvent. Among these catalysts, it was indicated that zirconium phosphate (ZrP)-supported Ni catalysts were highly efficient and recyclable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in lignin model compounds. The further investigation demonstrated that the transfer hydrogenolysis of the C–O bond is highly selective, which afforded phenols and aromatics as dominant products without the products arising from hydrogenation of aromatic rings. Through a series of characterization of the catalyst, it was demonstrated that the medium strong acid sites of the ZrP support promoted the cleavage of alkyl-aryl ethers (α-O-4 and β-O-4), and Brønsted acid sites favored for achieving high selectivity toward C–O bond cleavage. Additionally, Ni(0) sites on the ZrP catalysts were responsible for the catalytic transfer hydrogenolysis.