Hydrogenation of CO(2) Promoted by Silicon-Activated H(2)S: Origin and Implications

Unlike the usual method of CO(x) (x = 1, 2) hydrogenation using H(2) directly, H(2)S and HSiSH (silicon-activated H(2)S) were selected as alternative hydrogen sources in this study for the CO(x) hydrogenation reactions. Our results suggest that it is kinetically infeasible for hydrogen in the form of H(2)S to transfer to CO(x) at low temperatures. However, when HSiSH is employed instead, the title reaction can be achieved. For this approach, the activation of CO(2) is initiated by its interaction with the HSiSH molecule, a reactive species with both a hydridic H(δ−) and protonic H(δ+). These active hydrogens are responsible for the successive C-end and O-end activations of CO(2) and hence the final product (HCOOH). This finding represents a good example of an indirect hydrogen source used in CO(2) hydrogenation through reactivity tuned by silicon incorporation, and thus the underlying mechanism will be valuable for the design of similar reactions.