Facilely Synthesized CeNi1-xCoxO3 Perovskite Catalyst for Combined Steam and CO2 Reforming of Methane

Abstract

Herein, a series of CeNi_1-xCo_xO₃ (x = 0.1, 0.3, 0.5, and 0.7) was prepared by a co-precipitation method for combined steam and CO₂ reforming of methane (CSCRM) reaction. The influence of incorporating Ni with Co species in the perovskite structure was elucidated by both the catalytic performance and physicochemical properties of as-prepared materials. Several modern techniques were utilized to study the catalysts’ properties, including XRD, EDS, SEM, HR-TEM, Nitrogen adsorption–desorption, H₂-TPR, CO₂-TPD, and Raman spectroscopy. As Co modification content increased, respective to x value in CeNi_1-xCo_xO₃ change from 0.1 to 0.5, calcined catalysts’ crystallite size of separated M₂O_x oxides gradually increased from 16.2 to 20.3 nm. Investigating the CO₂-TPD and H₂-TPR profiles showed that CO₂ adsorption ability of catalysts increased while reducibility decreased when x value increased from 0.1 to 0.5. Despite clearly change of physicochemical properties, the Co content in range of x = 0.1–0.5 did not have significant influence on the catalytic activity in CSCRM reaction. The properties of catalyst with higher Co content (x = 0.7) changed differently compared to catalysts with x = 0.1–0.5, which seemed positive (smaller crystallite sizes of calcined perovskite and reduced metallic phases of 12.9 nm and 12.8 nm, respectively; slightly larger specific surface area of 13.0 m²/g, higher hydrogen consumption in TPR analysis), but the catalytic activity of this catalyst slightly lower than other surveyed catalysts at a low temperature of 550 °C. Despite that, all studied catalysts showed quite similar catalytic performance at high temperature range, which was considered as favorable operation condition for the reaction. The study also revealed an excellent coke tolerance ability of perovskite-derived catalysts in the CSCRM. The as-prepared CeNi_0.5Co_0.5O₃ catalyst showed a comparable activity compared to other published results on other catalysts, with CH₄ and CO₂ conversions of 94.6% and 93.2%, respectively. The comparison with other studies also revealed a high CH₄ conversion rate of 6381 mL_CH4.g⁻¹.h⁻¹ and an excellent CO₂ conversion rate of 3269 mL_CO2.g⁻¹.h⁻¹ on CeNi_0.5Co_0.5O₃ in a high space velocity of 3 × 10⁵ mL.g⁻¹.h⁻¹.