The Research Of Catalytic Combustion Of Hydrocarbon Fuels Over Zeolite Supported Pt Catalysts

Fuel tank explosion is one of the main threats to the aircraft flight safety.Green on-board inert gas generation system(GOBIGGS)is a new type of oxygen-consuming tank inerting system.Its working principle is that the mixed gas of fuel vapor and air over the fuel tank will be delivered to flameless combustion unit firstly,then the blending gas will take a flameless combustion reaction in the presence of catalyst to consume oxygen.The vapor in the product will be removed after condensation,the produced carbon dioxide will continue to participate in the tank inerting cycle.Finally,the oxygen concentration will be controlled below the safety line to avoid the fuel tank explosion.It is obviously that catalytic combustion reactor is one of the core components of GOBIGGS,and the performance of the catalyst is directly related to the oxygen consumption effect of the system.Basing on actual needs and our pre-research results,we conducted a systematic research of catalytic combustion of hydrocarbon fuel over zeolite-supported Pt catalysts.The effects of zeolite species,silica-alumina ratio,loading amounts of Pt,space velocity and relative humidity on the catalytic activity of the catalysts were investigated in this work.Firstly,ZSM-5 was chosen as the carrier to explore the influence of the Si/Al ratio of zeolite on the catalyst activity.The results show that in the four catalysts prepared by ZSM-5 with different Si/AI ratio(Pt/ZSM-5-60,Pt/ZSM-5-100,Pt/ZSM-5-200 and Pt/S-1),the Pt/S-lcatalyst prepared by the all-silicon ZSM-5 exhibit the best catalytic combustion activity to methylcyclohexane,which may be attributed to the relatively stronger hydrophobicity of the all-silicon carrier.Then,the influence of all-silicon molecular sieve species on the catalyst activity of catalysts was investigated.The results show that the Pt/Si-Beta catalyst prepared with the all-silicon Beta as carrier has the highest catalytic activity,which can completely catalyze the combustion of methylcyclohexane at 166? and maintain high efficient during the 25h catalytic test.This phenomenon may be related to the better hydrophobicity and methylcyclohexane adsorption capacity of the all-silicon Beta supporter.The effect of loading amounts of Pt on the catalysts activity was also investigated in the present work.The catalyst lwt%Pt/Si-Beta prepared by loading lwt%Pt on the all-silicon Beta exhibits excellent catalytic activity to both model fuels and aviation fuel.It can completely catalyze the combustion of methylcyclohexane,butylcyclohexane,n-dodecane and aviation fuel at 166?,217?,262? and 241?,respectively,which basically meet the technical requirements of GOBIGSS.Furthermore,when the working conditions of airspeed and relative humidity are changed,Pt/Zeolite still can exhibit good catalytic combustion activity to hydrocarbon fuels.