Study On Catalysts For Coupling Of Dehydrogenation Of Long Chain Alkane And Catalytic Combustion Of Methane

Monolithic catalysts are uni-body structures composed of narrow parallel straight passages which are arranged orderly. It can intensify process when used in the direct coupling of endothermic/exothermic reactions due to its advantages such as low pressure drop, favorable heat and mass transfer properties and uniform profiles of concentration,Compared with traditional pellet catalysts. As the preparative work, we investigated dehydrogenation of long chain alkane and methane catalytic combustion respectively in this paper. Besides, the experiments of the coupling of the CO₂-reforming of methane with catalytic combustion of methane have been carried out to test experimental set-up for directly coupling an endothermic reaction system with an exothermic reaction.For the strong endothermic reaction, firstly, the effects of operation parameters on the performance of long chain alkane dehydrogenation over catalyst used in industry presently were observed. The results showed that preheat-temperature affected the dehydrogenation performance obviously. Secondly, Pt-Sn-Li/Al₂O₃/FeCrAl catalyst was prepared by using FeCrAl alloy foils as the base of supporter and Pt-Sn-Li/γ-Al₂O₃ as the active coating. The results of activity tests showed that catalyst performance was remarkably influenced by the reaction temperature, the LHSV and the ratio of hydrogen to alkane. In addition, the effects of preparation conditions such as Pt loading, stirring time, dechlorination time and supporter were explored for pellet catalysts of Pt-Sn-Li/γ-Al₂O₃. The experimental results showed Pt loading, dechlorination time and supporter were three important preparation parameters.In the strong exothermic reaction, catalytic combustion of methane, A series of Pd/SiO₂ and Pd/5%Ce_xZr_1-xO₂/SiO₂ (x=0-1) catalysts were prepared by an impregnation method. The results indicated that the Ce_xZr_1-xO₂ could promote the dispersion and reducibility of PdO in the Pd/Ce_xZr_1-xO₂/SiO₂ catalysts, and consequently improved the catalytic activity.Finally, a metallic monolith catalytic element for coupling the CO₂-reforming of methane with catalytic combustion of methane was prepared. The results of coupling experiment successfully proved that the direct coupling of strong endothermic and exothermic reactions was feasible.