Slag-based geopolymer microsphere-supported Cu: a low-cost and sustainable catalyst for CO2 hydrogenation

Abstract

Recent studies on the exploration of sustainable approaches by utilizing large-scale waste materials as potential catalysts in the field of heterogeneous catalysis have attracted much attention. Using industrial waste as a catalyst or catalyst support has the advantages of being environmentally friendly and cost-effective. The reverse water gas shift (RWGS) reaction has been widely studied as an effective way to reduce CO₂ emissions. In this work, we used NaOH-activated slag-based geopolymer microspheres (SGSs) as supports to prepare catalysts with different Cu loadings by a simple impregnation method. The results showed that a 10% Cu/SGS catalyst exhibited the best CO₂ conversion performance. At a reaction temperature of 550 °C, the CO₂ conversion and CO selectivity of the 10% Cu/SGS catalyst reached 48% and 96%, respectively. It was found that the high performance mainly results from the interaction between Cu and the SGS support and the adsorption and activation of CO₂ by the basic sites on the SGS support. The findings regarding the performance of Cu/SGS catalysts and the associated reaction mechanism may significantly benefit further development of geopolymer support catalysts.