Continuous CO2 abatement via integrated carbon capture and conversion over Ni-MgO-Al2O3 dual-functional materials

Abstract

Massive emission of CO2 is one of the main contributors to global warming, and CO2 capture, utilization and storage (CCUS) was proposed as an indispensable option for carbon reduction. Recently, integrated carbon capture and conversion (ICCC) was regarded as a potential approach to lower the cost of CCUS, and development of efficient dual-functional materials (DFMs) is among the top priority in the area. Herein, Ni-MgO-Al2O3 DFMs were prepared by calcination of Ni-impregnated Mg-Al layered double hydroxide (MgAl-LDH), as such, the pre-loaded Ni species was actively involved in the decomposition of MgAl-LDH, therefore the synergy and balance of the adsorption and catalytic functionalities for ICCC can be promoted in the resulted DFMs. The optimized sample (20NiMgAl(500)) showed excellent ICCC performance. At 300 °C, continuous abatement of CO2 from simulated flue gas (15 vol.%CO2/N2) was achieved with an excellent efficiency of 280 L·h−1·kg−1. Composition analysis of the effluent gas demonstrated that over 97 % CO2 in the feed could be captured, and over 95 % of the captured CO2 was converted to CH4 with ∼ 100 % selectivity. Full retention of the adsorption capacity was observed for 10 adsorption-methanation cycles, and the post-reaction characterization of the DFMs indicated little structure change. This work may pave a way to the practical application of the ICCC technology, and also inspire other integration approaches between CO2 capture and the following mitigation technologies.