Eco-friendly upconversion of limestone into value-added calcium formate

Although CaCO 3 is a naturally available, inexpensive, abundant and extensively used chemical in various industries, to date, most of its conversions liberate CO 2 into the atmosphere, which accounts for about 5-6% of global anthropogenic CO 2 emission. Herein, the first synthesis of calcium formate (CF) by hydrogenation of an aqueous mixture of CaCO 3 and CO 2 using a heterogeneous catalyst in an unconventional CO 2 reducing manner is reported. The phosphine-based heterogenized Ru catalyst efficiently converts CaCO 3 into CF with good selectivity (>99%) and is readily separated from the reaction product, resulting in promising recycling ability. Thus, this work provides a promising strategy for the design of green and sustainable conversion of carbonate minerals in industry. We first report the heterogeneous conversion of CaCO 3 into calcium formate (CF) using an efficient bisphosphine-based Ru catalyst. The catalyst can be reused and the generated CF can be isolated in a very pure form.