Study On Catalyst And Membrane Reactor Of Propane Partial Oxidation With Carbon Dioxide To Propylene

There are the advantages of reducing deep oxidation of propane and discharge ofCO2 for reasonable use of carbon source by using CO2 for partial oxidation of propaneto propylene. Pd-Cu/VSiO and Pd/MoVSiO catalysts and supportedpolyimide-silica-silver (PI-SiO2-Ag/SiO2/K-M) and polyimide-titania-silver(PI-TiO2-Ag/SiO2/K-M) hybrid membranes have been designed and prepared forpropane partial oxidation to propylene with CO2 in conversional and membranereactor in order to increase the conversion of propane and selectivity of propylene.1.Pd-Cu/VSiO and Pd/MoVSiO were prepared by surface reaction and incipient wetness impregnation method. Its chemical structure, chemisorption properties and catalytic behavior for propane partial oxidation with CO2 were characterized by BET, XRD, IR, TPD, TPSR and microreactor techniques. Three active sites of metallic M, Lewis acid Vn+ and Lewis base V=O were presented on the surface of Pd-Cu/VSiO catalyst. Horizontally adsorbed CO2 formed on metal site and in the adjacent Vn+ was active adsorbed state and CO and lattice oxygen was formed by breaking of horizontally adsorbed CO2. Three active sites of metallic Pd, Lewis acid Vn+ and Lewis base V=O and Mo=O were presented on the surface of Pd/MoVSiO catalyst. Horizontally adsorbed CO2 formed on metal site Pd and in the adjacent Vn+ was active adsorbed state and CO and lattice oxygen was formed by breaking of horizontally adsorbed CO2. Propane adsorbed on lattice O(V=O) on the surface of Pd-Cu/VSiO and Pd/MoVSiO catalysts through H of methyl and methylene binary site was active, and propylene, water and oxygen vacancy was formed by desorption of adsorbent propane. The concentration of lattice oxygen on surface of catalysts was adjusted by CO2 as middle oxidant for this reaction, thus oxidation dehydrogenation of propane was proceeded. The selectivity of propylene was increased by competition adsorption of propylene and CO2.2.The PI-SiO2-Ag/SiO2/K-M and PI-TiO2-Ag/SiO2/K-M hybrid membrane were prepared by sol-gel route and characterized by means of SEM, IR, XRD, TGA, N2 adsorption and gas permeability measurements techniques. The viscosity of hybrid sol was increased and gel time was reduced by addition of inorganic sol and silver. Inorganic sol was linked tightly with PAA through hydrogen bond. Ag+ was dispersed in organic-inorganic networks by complexing with nitrogen of PI. The thermal decomposing temperature was increased by addition of silica, and it was reduced by addition of titania because of thermal catalysis. The average pore sizewas increased, pore distribution was dispersed, thermal decomposing temperature was reduced and permeable flux of propylene was increased by addition of silver. Separation factor of propylene/propane through PI-SiO2-Ag/SiO2/K-M hybrid membrane was higher compared with PI-TiO2-Ag/SiO2/K-M hybrid membrane. Separation factor of water/propane through PI-SiO2-Ag/SiO2/K-M hybrid membrane was lower compared with PI-TiO2-Ag/SiO2/K-M hybrid membrane.3.Membrane reaction performance for partial oxidation of propane to propylene with CO2 were studied over Pd-Cu/VSiO and Pd/MoVSiO catalysts in PI-SiO2-Ag/SiO2/K-M and PI-TiO2-Ag/SiO2/K-M hybrid membrane reactor. The reaction results in membrane reactor were compared with those in conversional catalytic reaction. The results showed that the conversion of propane and the selectivity of propylene were higher 4.94-8.91% and 3.42-4.36% than those in conversional catalytic reaction under comparable conditions, which in PI-SiO2-Ag/SiO2/K-M and PI-TiO2-Ag/SiO2/K-M hybrid membrane reactor were 17.23% and 96.57%, and 11.92% and 97.26% over Pd-Cu/VSiO catalyst, and those were 18.28% and 97.66%, and 14.32% and 97.98% over Pd/MoVSiO catalyst.