A packed-bed balance reactor for gas adsorption and gas-solid reactions under elevated pressures

Abstract

A packed-bed balance reactor (PBBR) is presented as a novel and relatively low-cost alternative to a microbalance for use in adsorption experiments and gas-solid reactions under elevated pressures. The apparatus consists of a packed-bed flow reactor placed, together with the inlet and outlet connections, on a commercially available electronic balance. This construction combines the advantages of a microbalance (direct weight measurement) with those of a packed-bed flow reactor (elevated pressure conditions, larger sample size and less severe external mass transfer limitations under flow conditions). The gas flow rate through the reactor does not affect the weight read-out, whereas the pressure dependency is caused by the amount of gas present in the reactor. The operating principle is demonstrated by CO₂ adsorption on activated charcoal under flow conditions and by gasification of activated charcoal with CO₂. Specific surface areas, calculated from adsorption isotherms, correspond well with those obtained from a conventional volumetric method. Gasification reaction rates based on the weight decrease equal those calculated from the gas flow rate and the product gas analysis.