Optimizing Ni MEPCM catalysts for thermal regulation in CO2 methanation: ZrO2-CaO surface doping

Abstract

CO₂ methanation has become a crucial part of the carbon recycling process owing to its potential to reduce greenhouse gas emissions from renewable hydrogen sources. The reaction is highly exothermic and, under inadequate control, may cause thermal runaway and lead to catalyst deactivation. Therefore, thermal regulation is crucial for ensuring optimum productivity. Microencapsulated phase change materials (MEPCM) were introduced as a promising thermal regulation approach because of their superior capability in controlling the system temperature using the latent heat storage (LHS) concept. This study aims to improve the effectiveness of MEPCM as catalysts support by incorporating mass transfer agent for CO₂ methanation process, building upon prior research which focuses on direct impregnation on MEPCM support. To accomplish this goal, a novel MEPCM catalyst structure was developed by loading a Ni metal active site onto the ZrO₂-CaO surface-enhanced MEPCM. Novel MEPCM catalysts were prepared using three sequential methods: MEPCM synthesis, surface modification, and catalyst impregnation. Characterization analysis revealed that the modification improved the surface area by 45%. ZrO₂-CaO doping successfully enhanced the catalytic performance by increasing the CO₂ conversion and CH₄ selectivity by 8 and 6%, respectively. In addition, the LHS function of the catalyst-loaded MEPCM suppressed the rapid increase in temperature during the initiation of CO₂ methanation. Further development of this concept is expected to enhance the efficiency of runway reaction control across numerous chemical industries.