Direct conversion of (bi)carbonate into methane using rare-metal hydrides : a promising approach for value-added fuels

Abstract

Converting carbonate minerals into value-added fuels presents a promising long-term approach for addressing global warming and energy supply challenges. In this study, we report a facile strategy for directly converting metal (bi)carbonates (M(H)CO3, where M represents Li, Na, K, Mg, or Ca, etc.) into CH4 using a series of hydrides (RNi5H6, R = rare metal) through ball milling under ambient conditions. Our findings reveal that the methanation reaction exhibits remarkable selectivity, with no detectable CO formation in any of the metal hydride-(bi)carbonate systems. The yield of CH4 mainly depends upon key factors such as the reaction duration, specific RNi5H6 species, H2/CO32- (or HCO3-) molar ratio, and metal (bi)carbonate sources. This work offers novel insights into deploying metal-based hydrides for carbonate reduction.