Optimized Reductivity of the NaBH 4 /ZrCl 4 System for Converting Carbon Dioxide into Methanol under Ambient Conditions without a Catalyst

The handling of CO 2 is one of the essential challenges for the world in this century. A favorable solution is to convert CO 2 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 NaBH 4 /ZrCl 4 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 CO 2 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 Cl 3 THF 2 ZrBH 4 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 CO 2 into methanol with high efficiency, low cost, and a plausible industrial cycle.