A New Catalyst For Dehydrogenation Of Isobutane To Isobutylene And Reaction Process

Isobutylene?i-C₄H₈?could be produced by Isobutane(i-C₄H₁₀)dehydrogenation reaction and further react with methanol through etherification reaction to produce MTBE.This is an important way to comprehensive utilize C4.Process based on Pt-Sn/Al2O3 catalyst with water vapor as diluent in a fixed bed for isobutane dehydrogenation to produce isobutylene were developed by The Physical And Process Simulation Laboratory of Beijing University of Chemical Technology.The technology will be used for 100,000 tons/year i-C₄H₁₀ dehydrogenation plant.In order to ensure the production and application at a large scale and operation of the industrial scale dehydrogenation unit,the catalyst was evaluated systematically on the 100ml pilot scale experimental unit in this study.A kinetic model of dehydrogenation reaction including the catalyst deactivation was established and used to simulate the industrial adiabatic axial fixed bed reactor for dehydrogenation.Finally,the whole system,especially the MTBE separation unit,where isobutene produced by dehydrogenation is separated,was simulated and analyzed by Aspen process simulation software.The catalyst for both the laboratory and industrial amplification processes was evaluated at the condition of i-C₄H₁₀ airspeed 900-1200h^-1,pressure 0.15-0.30MPa,H2/i-C-H10 ratio 0.5 mol/mol,H2O/i-C₄H₁₀ ratio 1.5mol/mol,temperature 510-610?..The results showed that the activity,selectivity and stability of the catalysts produced by industrial amplification have reached or exceeded the level of catalyst prepared in the laboratory.Activity,selectivity and stability of deactivated can be fully restored after regeneration.Under the above conditions,the catalyst has a minimum operating period of 14 days and a maximum of 39 days.A kinetic model of isobutane dehydrogenation to produce isobutene reaction including catalyst deactivation was established.The quasi-homogeneous model was used to simulate the industrial adiabatic axial fixed bed reactor for isobutane dehydrogenation in combination with the aforementioned kinetic model.Under the present operating conditions(i-C₄H₁₀ space velocity of 900 h^-1,H2/i-C₄H₁₀ ratio of 0.2 mol/mol,H2O/i-C₄H₁₀ ratio of 1.5 mol/mol),to maintain the conversion rate of isobutane at 20%in one-stage dehydrogenation reactor,the operating period is 31 days.Two-stage dehydrogenation reactor was operated for 34 days while maintaining 12.5%isobutane conversion.Influences of H2/i-C₄H₁₀,H2O/i-C₄H₁₀ ratios and pressure on the operation cycle of dehydrogenation reactor were studied by the developed reactor model.The simulation results are of great reference value for the optimization of industrial reactor.The distillation column of MTBE synthesis reaction and the dehydrogenation unit were simulated by Aspen Plus process software.The isobutene feed pressure,feed temperature,theoretical column number of the distillation column and the influence of reflux ratio on the isobutylene conversion rate were studied.The simulation results are of great significance for the design and operation of the MTBE synthesis reaction distillation column in industrial plants.