基于动态积/消碳平衡驱动的CH4干重整催化剂宏观动力学研究OA

[Purposes]Transition metal Ni is an important active component of catalysts for dry reforming of methane technology,but Ni-based catalysts are prone to deactivation because of carbon deposition and sintering at high temperatures.Based on previous dynamic equilibrium approach for coke/de-coking to comprehensively resolve catalyst deactivation in dry reforming of methane(DRM),the kinetic study of a self-developed highly stable Ni-Mo/Ce0.8Zr0.2/MgAl(O)catalyst(TYUT-HM-CZ)is performed at 873-1 173 K with CH4/CO2 partial pressure of 5-50 kPa.[Methods]By using the Power-Law(P-L)and Langmuir-Hinshelwood(L-H)models,the DRM reaction mechanism and dynamic equilibrium approach for coke/de-coking characteristics were discussed.[Results]Results of the multivariate non-linear fitting indicate that the P-L model provides superior fitting performance across the entire temperature range(R2>0.90).The apparent activation energy for CH4(32.2 kJ/mol)is significantly higher than that for CO2(15.1 kJ/mol).This confirmes that within the specified tested temperature range,methane cracking is the rate-determining step.The applicability of the L-H model will be limited at low temperatures(<873 K),probably owing to non-equilibrium reactant ad-sorption or additional complicating processes.While at elevated temperatures,the adsorption constant KCO2(0.012 86)>KCH4(0.008 50),reflecting CO2 preferential adsorption behavior.With increasing tem-perature,the CH4 reaction order α decreases from 0.99 to 0.59,increasing coking risk,while the CO2 order β increases from 0.22 to 0.62,enhancing decoking capability,which validates the feasibility of the'high-temperature dynamic coking/de-coking equilibrium'design concept.The TYUT-HMCZ catalyst shows stable laboratory operation for 658 h at 1 173 K and GHSV=60 000 mL/(g·h)(conver-sion rate>95%).Moreover,it undergoes over 200 h of experimental evaluation on a 600 m³/h pilot plant without signs of deactivation,indicating its industrial application potential.This study quantita-tively elucidates the dynamic competitive mechanism between coking and de-coking.[Conclusions]This paper elucidates the dynamic competitive mechanism between carbon deposition and removal through kinetic studies,and proposes a strategy of low-temperature control of CH4 cracking coupled with high-temperature promotion of CO2 activation to achieve the development of highly stable DRM catalysts and the optimisation of industrial reactors with varying reaction temperature conditions.