水素存在下におけるn-プロピルベンゼンの熱分解反応

抄録

Kinetics and machanism were studied on the pyrolysis of n-propylbenzene in the presence of hydrogen with a flow reactor made of quartz. The reaction conditions were in the ranges of temperature from 500 to 650°C, of molar ratio of hydrogen to n-propylbenzene from 3 to 6, and of residence time from 2.5 to 8.5 sec at the atmospheric pressure. The main reaction products were styrene, methane, ethane, ethylene, toluene, ethylbenzene and benzene. Small amounts of the other several compounds were also identified by GC and GC/MS.
It was suggested that the reaction proceeds mainly by the free radical chain mechanism as follows, initiation: the dissociation of n-propylbenzene to benzyl and ethyl radicals, propagation: the formation of 1-phenylpropyl radical by hydrogen atom abstraction of n-propylbenzene, and its consecutive decompostion into styrene and methyl radical, termination: the recombination of methyl, ethyl and benzyl radicals. Methane, ethane and toluene are formed by the atom transfer of methyl, ethyl and benzyl radicals respectively with hydrogen, and ethylene by the hydrogen atom elimination of ethyl radical, etc. Benzene is believed to be formed by hydrogenolysis of n-propylbenzene in the same mechanism as that of toluene reported previously.