Synthesis And Catalytic Performance Of Mesoporous ZSM-5 Supported Pt Catalysts

Green on-board inert gas generation system(GOBIGGS)is a new technique for explosion-proof of fuel tank,which can effectively implement the fuel tank inerting without affecting the overall performance of the aircraft.The system transmits the mixture of fuel vapor and air from the fuel tank ullage space of the aircraft to the gas catalytic combustion unit through a low-pressure pump.With the presence of catalyst,oxygen in the tank is consumed.Water in the product is separated,CO2 and the remaining N2 are transferred back to participate in the fuel tank inerting.After several cycles,the oxygen content can be controlled below the safety line quickly to ensure the airworthiness of the aircraft.Obviously,the catalytic unit plays a crucial role as the core component in the GOBIGGS,and the performance of catalyst is an important factor affecting the efficiency of the whole system.In this paper,a series of mesoporous ZSM-5 supported Pt catalysts are prepared.The effect of silicon-aluminum ratio,cation,space velocity,Pt loading and defects on the performance of catalysts for the lame-free combustion of hydrocarbon fuels is discussed in detail.Mesoporous ZSM-5 molecular sieves with different Si/Al ratios(60,100,300,?)were prepared by hydrothermal synthesis method,then a series of Meso-ZSM-5 supported Pt catalysts were obtained.Catalysts containing different cations(H+,Na+,K+)were obtained by ion exchange method.The activities of these catalysts for flameless combustion of methylcyclohexane were investigated.Results show that Pt/Meso-KZSM-5-100 catalyst has the best catalytic activity in all tested catalysts,which can catalyze the complete combustion of methylcyclohexane at 171?.Combined with the characterization of catalysts,it can be found that Pt0 plays a major role in the catalytic combustion of hydrocarbon fuels.The sintering resistance of the catalyst is an important factor for using.In this paper,molecular sieve with defects was prepared by means of partial aluminum removal at high temperature,then the precursor of noble metal was reduced at the defects,and catalysts with high stability were obtained.By comparing the stability of common catalysts with that of catalysts with defects,we found that the catalyst containing defects had good anti-sintering performance,and its catalytic activity did not decrease after 60 h of continuous catalytic reaction.Finally,Pt/trap-Meso-KZSM-5-100 catalyst with good comprehensive performance was selected for the experimental study on catalytic combustion of tetrahydronaphthalene,isopropylcyclohexane,JP-10 and RP-3.The results demonstrated that the catalyst had good catalytic activity and longevity for flameless combustion of hydrocarbon fuels.