A STUDY OF A TUBE-WALL REACTOR WITH HEAT-EXCHANGER FUNCTION

A chemical heat pump with a reaction couple of cyclohexane dehydrogenation and benzene hydrogenation was proposed to utilize waste thermal energy. In this system, a wall-type reactor with high thermal conductivity is needed to transform thermal energy efficiently into chemical energy. A thin-layer catalyst supported on a metal has high thermal conductivity and well suits the wall-type reactor. In this study, we determined a rate equation of dehydrogenation of cyclohexane. The reaction rate was found to be controlled by the adsorption rate of cyclohexane molecules on the catalyst surface. Then, conversion and temperature distributions of a tube-wall reactor and of a fixed-bed reactor were calculated. The optimal response was obtained at around 300-degrees-C. The resistance at 20 ppm NO2 was about 10 times as large as that in air at 300-degrees-C and the response time was about 60 s. The sensitivity to NO was one-fifth of that to NO2. The film shows very low sensitivities to hydrogen, carbon monoxide and hydrocarbons. It was demonstrated that the tin oxide film shows a high sensitivity and selectivity to NO2 which suggests possible use as a NO2 sensor in exhaust gases.