Promotion effect of CO on methanation of CO2-rich gas­­ over nanostructured modified NiO/γ-Al2O3 catalysts

Pham Noa Uy Do, Cam Loc Luu, Phung Anh Nguyen, Thi Thuy Van Nguyen, Tien Cuong Hoang and Tri Nguyen

Abstract

Catalysts NiO/γ-Al₂O₃ non-promoted and promoted with CeO₂, MgO, CaO and Pt have been prepared by the impregnation method and used for hydrogenation of carbon oxides into high caloric synthetic fuel CH₄. Physico-chemical properties of catalysts were determined by the methods of Brunauer–Emmett–Teller surface area analysis (BET), x-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), carbon dioxide temperature programmed desorption (CO₂-TPD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The activity of catalysts was investigated for CO₂ solo-hydrogenation and co-hydrogenation of CO and CO₂ mixture at temperature range of 225 °C–400 °C. The particle size of all samples was found to distribute in a range of 15 °C–45 nm and the catalysts' surface area varied from 79 to 95 m² g⁻¹. Additives increased the thermal stability of catalyst and enhanced the dispersion and reducibility of NiO that led to improve the activity and selectivity of methanation of carbon oxides into CH₄. On these catalysts, CO completely converted at 250 °C–275 °C and 80%–90% of CO₂ was converted at 400 °C. Addition of CO in feedstock enhanced the efficacy of methanation of CO₂-rich gas, increasing CO₂ conversion by 3%–25% and rising CH₄ selectivity up to 95%–100%