Modeling and simulation of methane dry reforming in direct-contact bubble reactor

• Published in: Solar energy 2014-04, Vol.102, p.45-55
• Main Authors: Al-Ali, Khalid, Kodama, Satoshi, Sekiguchi, Hidetoshi
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Bubbles; Carbon dioxide; Catalysis; Catalysts; Catalysts: preparations and properties; Catalytic reactions; Chemical reactors; Chemistry; Computer simulation; Direct-contact bubble reactor; Energy; Exact sciences and technology; Fuels; General and physical chemistry; Hydrogen; Hydrogen production; Mathematical models; Methane; Methane dry reforming; Modeling; Reaction kinetics; Reactors; Reforming; Simulation; Software; Solar reformer; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2014.01.010

In a DCBR, the formation and ascension of reactant bubbles of a mixture of CH4 and CO2, come into direct contacts with the suspended particles of a catalyst which existed everywhere in a thermal fluid. Consequently the endothermic methane dry reforming proceeds across the available contact areas, termed as total catalytic active surface area (T-CASA). Moreover, the bubble rising terminal velocity determines the gas bubble residence time, or contact time for interfacial transport whereas the residence time determines the conversion efficiency. Modeling and simulation of such processes provide useful information for a proper solar reactor design, e.g. reactor dimensionalization, parameters optimization, etc. •Essential reaction characteristics of direct-contact bubble reactor were identified.•Catalyst–bubble contact model was developed to predict catalytic activity.•Temperature, residence time, and total catalytic active surface area, are most influential reactor parameters.•Elimination of non-desirable water by-product can be obtained at specified inlet gas feed ratio. Modeling and simulation of the reforming behavior of a mixture of methane and carbon dioxide in a direct-contact bubble reactor (DCBR) was described. The endothermic catalytic reaction obeys the kinetics of the methane dry reforming in a direct-contact bubble reaction system containing an active catalyst, i.e., Ni–Al2O3 catalyst and molten salt mixture system. The reforming process was simulated, using commercial software for chemical kinetics, for a single reactor model, to examine a kinetic model based on the postulated heterogeneous reaction mechanism, in the temperature range 600–900°C, at 1atm. The simulated data were evaluated and validated with the measured data from a laboratory reformer. The catalyst activity in the DCBR was characterized using a catalyst–bubble contact model, in terms of the total-catalytic active surface area. We used the detailed simulation studies to identify the essential characteristics of the reaction mechanism in a DCBR.