Evaluations of the methane−carbon dioxide component of a carbon reforming process over a Ni/γ-Al2O3 catalyst were performed in a fixed-bed reactor at 1023, 1073, and 1123 K. The fitting of mass balance equations, including kinetic rate laws based on a mechanism proposition of three reaction steps, was formulated following experimental indications, where each step of the reaction system was individually evaluated. The comparison between experimental and calculated concentrations of the reactants and product effluents of the fixed-bed reactor leads to the estimation of the order of magnitude of the kinetic parameters corresponding to the reaction steps. The model was validated with the syngas selectivities evolutions at 943−1146 K.
The reforming of methane with CO2 was carried out efficiently in a fluidized bed reactor at 973 K under atmospheric pressure, taking advantage of the nickel catalyst efficiency achieved with a bed of particulate fines. The fluidization operation was characterized by determining a minimum velocity of 3.11 × 10−3 ms−1 and higher velocities. The reactor worked with surface speeds of up to 1.84 × 10−2 ms−1, providing conversions from 45% to 51% and a syngas yield of 97%. The control base of the operation focused on the use of CO2 was established through the reaction steps assumed for the process, including methane cracking, reverse Boudouard reaction, and RWGS (reverse reaction of water gas-shift). The reactor designed to operate in two zones was able to simultaneously process surface reactions and catalyst regeneration using feed with 50% excess CO2 in relation to methane. Predictions indicating the production of syngas of different compositions quantified with the H2/CO ratio from 2.30 to 0.91 decreasing with space-time were validated with the results available for process design.
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