Effect Of Oxygen On Propane And Propylene Pyrolysis Process In Empty Tubular Reactor

Propylene being the most important feedstorcks in chemical industry has a various implication. Propane dehydrogenation which is an important process for producing propylene has been industiled. Oxidative propane dehydrogenation (OPH) and propane dehydrogenation-selective hydrogen combustion (PDH-SHC) have been the hot point for its advantange in unlimited chemical eqlibrium and low energy cost. Adopting a flow turbular reaction system, series experiments have been performed to investigate the effect of material of reactor, fraction of oxygen, temperature, packing on propane and propylene pyrolysis process, with the aim of grasping some information to optimize the PDH process. The reactor material has great impact on pyrolysis reaction; Quartz reactor seems inertia in low temperature and unable to activate propane or propylene; Gas phase reations proceed at a high rate above600℃yielding methane, propylene, ethylene and hydrogen in propane pyrolysis in absence of oxygen; Some heavy hydrogencarbon may be present under high conversion; Propylene seems stable and have a low conversion. Stainless steel reactor can both activate propane under low temperature and catalyze propylene to coke in absence of O2, the later may be the major role of metal in the later stage of reaction when enough alkene has been formed. Oxygen functions together with the construct of reactor and temperature. In quartz reactor, oxygen mainly paiticipate in the gas phaes free radical reactions prompting the conversion of propane; Propylene, methane, ethylene and hydrogen are major products in high temperatue zone, while in low temperature zong, oxygen containing organic compounds consist of the product. Oxygen behaves differently in stainless steel reactor, the role of which lies in surface catalyzed deep oxidation and coking reaction, yielding CO2, H2O and coke. The role of hydrogen differs with material of reactor. While hydrogen can be oxidized by oxygen selectively on the inner surface of metallic reactor, it mainly participates in gas-phase radical reactions, in the form of OH radical, prompting conversion of propane and yields of products in quartz reactor. Conversion of propane and propylene can be prompted in stainless steel reactor treated with oxygen under high temperature.