Catalytic oxidation of hydrogen—intrapellet heat and mass transfer

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Abstract
Rates of oxidation of hydrogen were measured by using platinum–alumina catalyst particles and 1.86‐cm. pellets. For high‐reaction rates, temperature differences between center and surface of the pellets were more than 300°C. Under these conditions large variations in temperature with position on the pellet surface were observed. The pellet reactor was of the recirculation, stirred‐tank type with injection nozzles. Local heat transfer coefficients between pellet and gas varied twofold with location on the surface. The data showed that intrapellet heat and mass transfer resistances were both important, while between pellet and gas only the heat transfer resistance was significant.The effective thermal conductivity of the pellet was measured independently. By using this and the experimental temperature measurements, a new method s devised to establish the effective diffusivity under reaction conditions.Effectiveness factors were predicted from ke and De and the rate data for the particles. The results were about 7% greater than the experimental effectivenes lactor.