The Pore Structure of Poly(vinyl chloride) Char Activated with Ammonia Gas

Abstract

PVC char was prepared. by heat treatment of carbon residues, obtained by heating poly(vinyl chloride) powders with concentrated sulphuric acid at about 150° C, in a nitrogen atmosphere at 900° C for 2 hours. The activation reaction of the char with ammonia gas obeyed first order kinetics, having about 42 kcal/mol Of apparent activation energy in the range of 800° to 1000° C. From differential proe-volume distribution curves for the activated PVC chars, the increase in pore-volumes was observed mainly in the micropore regions and it was correlated with rather the weight loss than the temperature in the activation process. The change in the micropore volume in the chars estimated from Dubinin plot indicated that the micropores (dS30 A) were excavated and developed with activation up to the weight loss of about 50% and successively the transitional pores (30 A<d<300 A) were developed remarkably. It was found from electron microscopic observations that the char had well-developed macropores.