Akademik Veri Yönetim Sistemi
Microporous and Mesoporous Materials, cilt.396, 2025 (SCI-Expanded, Scopus)
CO2 methanation was investigated over mesoporous zeolite-supported Ni catalysts promoted with La2O3 and CeO2 at atmospheric pressure and within a temperature range of 150–400 °C. Three types of zeolites (BEA, ZSM-5, US-Y) were employed as supports, which were modified via post-synthesis dealumination and desilication to generate mesopores that enable Ni nanoparticle encapsulation and mitigate sintering. Among these, Ni catalyst supported on Na+-BEA exhibited significant enhancement in low-temperature catalytic performance upon promotion with La2O3 and CeO2. At 250 °C and a gas hourly space velocity (GHSV) of 12,500 h−1, CO2 conversion increased from 3 % to 30 %, while CH4 selectivity improved from 94 % to 99 %. These enhancements are primarily attributed to increased surface basicity. CeO2 promotion also improved the low-temperature reducibility of NiO, facilitated optimal Ni0 size (8 nm) through enhanced Ni dispersion, and introduced additional nickel-promoter interactions such as Ni−O−Ce, as indicated by H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy analyses. Furthermore, density functional theory (DFT) calculations revealed that the addition of Ce or La improved the CO2 adsorption energies and changed the mechanism to a CO∗- and HCO∗-mediated formate pathway. Notably, Ni-CeO2/Na+-BEA having a Si/Al ratio of 38 achieved 70 % CO2 conversion and 99.5 % CH4 selectivity at 300 °C under a H2:CO2 ratio of 4:1 and a constant GHSV of 12,500 h−1. The catalyst maintained stable methanation activity over 30 h, during which the Ni0 particle size remained at 8 nm.