Preliminary Study Of Catalytic Decomposition Of Methanol In Cooling Channel

Thermal cracking of endothermic fuel is an effective approach to remove wasteheat of aircrafts. But the actually heat sink of hydrocarbon fuels is around3.5MJ/kg,while producing a large number of coke. Therefore, a controlable reaction dirction is aimportant research direction to improve hent sink and reduce coking. Methanoldecomposition to hydrogen and carbon monoxide is an endothermic reaction with atheory heat sink of5897kJ/kg at1000K. The feasibility of methanol been anendothermic fuel used in active cooling technology is taken off. Herein the catalyticdecomposition of methanol was studied in an electrically heated tube reactor under4MPa over wall-coated Pd/Al₂O₃, Pt/Al₂O₃Ag/Al₂O₃. Lastly, the cracking patterns ofmethanol and n-decane composite fuel is studied.The heat of reaction, gibbs free energy and the equilibrium constant of methanoldecomposition to H₂and CO are analyzed. The results shows that using catalystwould avoid the formation of dimethyl ether and water at a low temperature. And theselectivity of methanol decomposition to H₂and CO is high when the temperature ishigher than523K.The parameters of methanol thermal and catalyst decomposition including heatsink, cracking rate, coke and product distribution are studied under high temperatureand high pressure （600℃，4MPa）. Then the different types and different loadings ofcatalysts are using to methanol decomposition. Results show that the total heat sink of5%Pd/Al₂O₃catalytic decomposition of methanol reaches up to4237kJ/kg at aconversion of68.87%,（600℃）, which is ca.28.78%higher than that of thermaldecomposition of methanol. The selectivity of the decomposition of methanol is over97%. The amout of CO2in gas products decide how much the coke formation. Themore CO₂is, the more amount of carbon.The use of methanol together with n-C10is a promising way to promote the heatsink and maintain the combustion heat of fuels. In detail,10%methanol&90%n-C10has a heat sink of3782kJ/kg at680℃, which is7.29%increase in comparisonto n-C10（3525kJ/kg）. Moreover, the production of hydrogen via methanoldecomposition can increase the yield of ethylene, methane and ethane and reduce thecoke during fuel cracking.