- Baojian Shen, China University of Petroleum
Zeolite is the active component of a fluid catalytic cracking (FCC) catalyst, it play a significant role in the hydrocarbon catalytic cracking via the generation of carbenium ion, thus, carbenium ion chemistry is the fundamental of hydrocarbon catalytic cracking process. Till now, the accepted understanding is that ‘the carbenium ion generate and further react with the middle or light distillate to finish the catalytic cracking reaction within the channel and/or cage system of zeolites, the lifetime of the carbenium ions and the nature of the zeolite do not permit it to diffuse out to the crystal of the zeolite’, and the ‘bulky heavy oil molecule can only be cracked on the outside surface of zeolite or on the matrix surface of the catalyst’. However, our recent research results push us to study the function of zeolite in heavy oil catalytic cracking again, the model compound evaluation results imply us: the carbenium ions might diffused out to the crystal of the zeolite and it contributed to the catalytic cracking of bulky molecule as well as a real feed of heavy oil. This understanding is helpful to the design of heavy oil FCC catalyst.