Sulong Shi,Yuxi Zhang,Yue Pan,Xin Liu,Fuhong Zhang,Hongyuan Yang,Qingya Liu,Zhenyu Liu
Hydrogenation of calcium carbonate (CaCO 3 ) directly yields calcium oxide (CaO), carbon monoxide (CO) and methane (CH 4 ) with little dioxide ( CO 2 ) . It therefore is promising to retrofit the industries, such as the cement, refractory, calcium carbide and steel, that rely on CaCO 3 calcination for CaO but emit large amounts of CO 2 . To lower the hydrogenation temperature of CaCO 3 and to promote CH 4 production efficiency and selectivity this work investigates the catalytic effect of various nickel compounds on the CaCO 3 hydrogenation for CH 4 . Among the NiCO 3 , NiO, Ni 2 O 3 and Ni doped in CaCO 3 , NiCO 3 is the most active catalyst. It is hydrogenated to yield highly dispersed Ni in CaCO 3 at temperatures around 600 K, while the Ni catalyzes CaCO 3 hydrogenation for CH 4 at temperatures higher than 640 K, which are about 150 K lower than the non-catalytic CaCO 3 hydrogenation. The doping of 0.50% NiCO 3 converts 99.0% CaCO 3 to CH 4 . The catalytic CaCO 3 hydrogenation for CH 4 and CO can be modeled by the Shrinking core model (SCM) that shows activation energy ( E a ) of 110.0 kJ mol −1 for CH 4 production when 0.50% NiCO 3 is doped, which is lower than 211.9 kJ mol −1 for non-catalytic hydrogenation.
The exploitation of highly active and stable catalysts for reduction of CO2 and water oxidation is one of the approaches to facilitate scalable and sustainable CO2 reduction potentially at the industrial scale. Herein, a feasible strategy to rationally build an overall CO2 + H2O electrocatalytic reaction device is the preparation and matchup of a high-performance CO2 reduction catalyst and low-cost and highly active oxygen anode catalyst. A heterostructured nanosheet, γ-NiOOH/NiCO3/Ni(HCOO)2, exhibited superior catalytic activity in the oxygen evolution reaction, and was integrated with CoPc/Fe–N–C to build an overall CO2 + H2O cell with a current density of 10 mA cm−2 at a very low cell voltage of 1.97 V, and the faradaic deficiency of CO2 to CO was maintained at greater than 90% at 1.9 V.
Conversion of calcium carbonate (CaCO3) to calcium oxide and methane (CH4) by renewable hydrogen is promising to retrofit the current CaCO3 decomposition processes in many industries and, at the same time, to replace their carbon dioxide emission by CH4 generation. This work studies CaCO3 hydrogenation by a liquid organic hydrogen carrier, 9,10-dihydrophenanthrene (DHP), and the catalytic effect of nickel carbonate (NiCO3) at 400 °C. It is found that NiCO3 in situ forms Ni particles of 200–900 nm in size that promote CH4 formation from CaCO3. At the NiCO3:CaCO3:DHP molar ratios of 1:10:55 and 400 °C, the total CO32– conversion, CH4 selectivity, and CH4 formation from CaCO3 are 89.5, 40, and 80.3%, respectively, in 40 min.
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