Mechanistic Kinetic Model for Biogas Dry Reforming

A thermodynamically consistent mechanistic kinetic model for dry reforming of biogas/CH4 (DRM) is developed. Since reverse water gas shift (RWGS) reaction always occur alongside DRM, the overall rate is expressed in terms of individual rates of DRM and RWGS reactions. In order to identify the rate-limiting steps for the derivation of mechanistic kinetics, a microkinetic model is initially developed and validated against experimental measurements. Reaction rate analysis and partial equilibrium analysis are then performed on the microkinetic model to identify the rate-limiting steps. The parameters of the mechanistic kinetic model are estimated using a genetic algorithm. t statistic is performed to establish the confidence level of the estimated parameters. A brute-force sensitivity analysis is performed to identify the most sensitive parameters in the microkinetic model. The models are validated over wide ranges of conditions

Kinetics of iron oxide reduction using CO: Experiments and Modeling

Reduction of iron ore is central to iron and steel making process. The reaction kinetics are generally studied using classical models that are based on the mechanism of interface control, nucleation control, or diffusion control. This paper presents a different approach in which physical governing equations for the solid phase are solved simultaneously with the gas phase transport equations. The reaction rate is calculated using shrinking core model and the parameters for kinetic term are estimated using genetic algorithm. The model is validated using data collected from experiments performed using iron ore pellets in a packed bed reactor and iron ore powder in a TGA apparatus. The reduced samples are subjected to SEM analysis to observe the microstructural changes that occur as a result of high temperature reduction. The paper further discusses, the applicability of the classical models in describing the different stages of reduction. © 2022 Elsevier B.V

Experimental studies of catalyst deactivation due to carbon and sulphur during CO 2 reforming of CH 4 over Ni washcoated monolith in the presence of H 2 S

This study presents the CO2 reforming of CH4 over Ni coated monolith catalyst at 800°C and 101.325 kPa. The high CH4 to CO2 ratio employed in this study is similar to the CH4:CO2 ratio of >1 found in biogas. Cordierite monolith samples (0.258 channels per m2) washcoated with alumina are used for the experimental purpose. The study considers the combined deactivation effect due to sulphur poisoning and fouling due to carbon deposition. Four different cases with respect to the introduction and removal of H2S are considered. The rate of deactivation due to simultaneous carbon deposition and sulphur poisoning is much faster than the individual poisoning processes. The catalyst shows almost stable operation for 6 h without the presence of (Formula presented.) in the feed stream. From the conversion studies, it appears that the pre-treatment of catalyst samples with H2S leads to negligible sulphur coverage. The sulphur poisoning effect is also found to be reversible. © 2021 Canadian Society for Chemical Engineering