Ni/CaO-ZrO2-Al2O3 Catalyst for CO2 Methanation: Enhanced Low-Temperature Activity and High-Temperature Sintering Resistance
Ni/Al2O3 is regarded as one of the most promising catalysts for industrial CO2 methanation, yet it suffers from inadequate low-temperature activity and thermal sintering. To address these challenges, an Ni/CaO-ZrO2-Al2O3 catalyst with high low-temperature activity and robust high-temperature sintering resistance was developed by introducing Ca and Zr promoters. Under reaction conditions of 250 °C and a space velocity of 30000 mL/(g·h), the catalyst achieved a CO2 conversion of 96% and a methane space-time yield of 257.5 mmol/(g·h). In a 200 h aging test at 600 °C, the Ca-Zr dual-promoted catalyst exhibited a smaller increase in Ni particle size and less activity loss compared to the Ca-promoted counterpart. Characterization revealed that Ca and Zr promoters not only improve Ni dispersion but also enhance surface basicity, contributing to excellent low-temperature activity. Furthermore, Zr suppresses the transformation of Ca species into CaCO3 via solid-phase reaction under operating conditions, thereby inhibiting Ni sintering and ensuring high-temperature stability. This work provides a novel promoter design strategy for developing high-performance Ni-based catalysts for CO2 methanation.