Heterogeneous Catalytic Transfer Partial-Hydrogenation with Formic Acid as Hydrogen Source Over the Schiff-Base Modified Gold Nano-Catalyst
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The catalytic hydrogenation transformation with gaseous hydrogen in liquid phase always refers to a harsh condition and over-hydrogenation, and it is highly desired to develop new methods with partial-hydrogenation at mild condition. Herein, a heterogeneous catalytic transfer partial-hydrogenation strategy with formic acid as hydrogen source was developed over the Schiff-base modified gold nano-catalysts. The Au/Schiff-SiO2 catalyst was successfully prepared by one pot aldimine condensation and NaBH4 reduction of a gold precursor. The characterization results indicated that the gold nanoparticles with an average size below 2 nm were highly dispersed over the Schiff-base modified silica support. Such Schiff-based gold nano-catalysts exhibits excellent activity and partial-hydrogenation selectivity, with a high yield (>99%) for phenylacetylene partial-hydrogenation and achieving a 75% chemoselectivity for imines at a relative low temperature and atmospheric pressure. More importantly, the excess of formic acid can be removed by the direct dissociation of formic acid over Au/Schiff-SiO2 catalyst with CO2 emission into atmosphere, which leads to a hydrogen source as clean as hydrogen gaseous, but with a much more high activity and selectivity under mild reaction process.
KeywordsGold catalysis Formic acid Catalytic transfer hydrogenation Phenylacetylene partial-hydrogenation Imines
This work was supported by the National Natural Science Foundation of China (21676045, 21176037, 21373037, 51273030 and 21403026), the Fundamental Research Funds for the Central Universities (DUT15LK29 and DUT16RC(4)03).