Kinetics of gas to particle conversion in the NH 3-HCl system

Abstract

Particle formation in the reaction of NH 3 and HCl under 1 atm of N 2 and at 25°C was studied in a flow reactor. The critical concentration below which no particle can be formed was found to be 3.5 × 10 14 molecule cm −3 for [ NH 3] = [ HCl]. Above this concentration, gas-particle conversion percentage increases rapidly to approach 100%. Particle nucleation was found to behave according to the rate equation R{ N} = k nuc {[ NH 3][ HCl]} n , where R { N} represents particle production rate, n = 2.7 and k nuc = 1 × 10 −(76 ± 15) cm 13.2s −1. Particle growth was attributed to the condensation reaction. Condensation rate coefficient was calculated from the equation: R{ NH 4 Cl( s)} = k con [ NH 3][ HCl][ N], where RNH 4 Cl( s) is the rate of NH 4Cl formation in the solid phase and the rate coefficient for condensation, k con , was found to be 7 × 10 −26 cm 6 s −1.