Gas-solid reactions: an unusual observation in the disproportionation of potassium benzoate to terephthalate

Abstract

An unusual experimental observation for a gas-solid reaction system, viz. disproportionation of potassium benzoate to terephthalate in the presence of CO₂, is reported. A uniform mixture of potassium benzoate and cadmium chloride as catalyst was used in the form of cylindrical pellets. It was observed that the reaction initiates at the centre forming a homogeneous reaction zone that expands radially outwards. This is explained on the basis of an "expanding core model" in complete contrast to the more common shrinking core model.