Mechanistic-fuzzy kinetic model for CO2 methanation over Ni-CeO2/γ-Al2O3 catalyst under industrial reactor conditions

• A kinetic study on Ni-CeO 2 /γ-Al 2 O 3 catalysts for CO 2 methanation was performed at a wide range of reaction conditions. • Methane reaction rates were unaffected by external mass transport resistances. • Experimental data aligns with a power-law model incorporating H 2 O inhibition effects. • A mechanistic-fuzzy kinetic model that incorporates both HCOO – and CO mechanisms was proposed. • The proposed LHHW expression is suitable for designing industrial methanation reactors. This study aims to develop mechanistic kinetic models applicable to the operating conditions of industrial methanation reactors and presents a thorough experimental investigation of CO 2 methanation on Ni-CeO 2 /γ-Al 2 O 3 catalysts. A wide range of reaction conditions was investigated, including temperature (423–823 K), pressure (1–21 atm), gas hourly space velocity (GHSV: 1,815,446–3,630,931 h -1 ), and H 2 /CO 2 ratios (2–5). The influence of mass transport resistances and the addition of products such as CH 4 and H 2 O on the methane reaction rate (r CH 4 ) was also investigated. A data set comprising of 93 experimental runs was used to develop a kinetic model capable of accurately predicting the reaction rate. Ni-CeO 2 /γ-Al 2 O 3 catalysts shows an apparent activation energy of 45.16 kJ·mol − 1 . Data obtained under differential conditions adjust quite precisely to a power-law model with H 2 O inhibition. Based on in-situ DRIFTS results, a mechanistic-fuzzy kinetic model where formate and direct carbon dissociation pathways are considered was proposed. By complementing both routes, this mechanistic kinetic model demonstrated high accuracy, with an absolute mean deviation of 9.53 %. Therefore, this model provides a reliable framework for the design of industrial scale methanation reactors under wide range of reaction conditions.