Effects of calcium chloride addition on the soot formation characteristics of ethylene pyrolysis in a laminar flow reactor

Abstract

The influence of calcium chloride (CaCl₂) addition at the ppm level (up to 60 ppm) on soot formation during ethylene pyrolysis in a laminar flow reactor at the temperature of 1673 K was experimentally investigated by studying soot properties, including particle size distribution (PSD), morphology, charge characteristics, and mass-mobility relationships. We found that at short residence times, calcium-containing nuclei are formed prior to soot nucleation, which become “core-shell” particles with the deposition of soot particles, and finally “core-shell” particles coagulate to form calcium-containing aggregates. On the other hand, particle coagulation is inhibited by the addition of CaCl₂ at longer residence times. The combination of the two competing effects can be well reflected in the PSDs and the mass-mobility relationship.