EFFECTIVE THERMAL-CONDUCTIVITY OF MONOLITHIC AND POROUS CATALYST SUPPORTS BY THE MOMENT TECHNIQUE

The axial and radial effective thermal conductivities of a monolithic ceramic catalyst support and of porous alumina pellets were measured u sing the moment technique. At 180 degrees C, radial and axial thermal diffusivities were determined as 9.3 x 10(-3) and 11.1 x 10(-3) cm(2) s(-1), respectively. Having pores being filled with hydrogen, the corr esponding thermal conductivity values are 0.43 and 0.52 W . m(-1). K-1 , respectively. Experimental results obtained between 110 and 180 degr ees C indicated a negligibly small dependence of effective thermal con ductivities on temperature. A proposed model which included the geomet rical parameters of the monolith and the thermal conductivity ratio of the ceramic catalyst support to gas was shown to give excellent agree ment with experimental results. Thermal conductivities of alumina pell ets having bidisperse pore structures were also measured using this dy namic procedure. Experimental effective thermal conductivity values ra nged between 0.043 and 0.120 W . m(-1). K-1 for pellets having porosit ies between 0.79 and 0.57, respectively.