Abstract: The behavior of catalytic cracking and thermal cracking of straight-run naphtha was investigated over ZRP catalyst and kaolin thermal medium respectively. The results indicated that compared with thermal cracking, catalytic cracking of naphtha occurred at lower temperature with higher conversion and higher yield of cracked gas, especially, the yields of ethylene and propylene increased 2—3 percentage point and 5—7 percentage point, respectively. The volume fractions of components in dry gas from catalytic cracking and thermal cracking reactions were different; it could be attributed to the cracking reaction pathway varied with temperature. The changing trends of the gasoline compositions in catalytic cracking and thermal cracking were similar based on the composition of feedstock, of which naphthenes were apt to take part in sorts of reactions and aromatics increased greatly at high temperature.

Key words: naphtha, catalytic cracking, thermal cracking, ethylene, propylene