Optimized Reductivity of the NaBH4/ZrCl4 System for Converting Carbon Dioxide into Methanol under Ambient Conditions without a Catalyst.

The handling of CO2 is one of the essential challenges for the world in this century. A favorable solution is to convert CO2 into alcohol products through an economical process. High temperature, high pressure, and catalysts are usually required for this task. Herein, we challenge the general concept for the reduction system NaBH4/ZrCl4 with a molar ratio of 4:1 in organic synthesis and confirm the molar ratio of 1:1 as the optimized composition, which exhibits ultrahigh activity to reduce CO2 to methanol with a yield of 72.5% and a selectivity of ∼100% at room temperature and ambient pressure without an additional catalyst. The active intermediate and subproduct have been successfully isolated and fully characterized as Cl3THF2ZrBH4 using synchrotron techniques and other measurements. This method investigates a new reduction system for organic synthesis and could provide a practical way for the absorption and conversion of CO2 into methanol with high efficiency, low cost, and a plausible industrial cycle.