N-Butyl-cyclohexane as a probe molecule to evaluate fresh and deactivated zeolite acid catalysts

The fluidized catalytic cracking (FCC) process converts heavy petroleum fractions into lighter hydrocarbons for use as fuels and petrochemicals. Even though it is a mature process, several improvements have been achieved by FCC catalyst development. Here, we study the cracking of n-butyl-cyclohexane (nC4CyC6) to establish a model catalytic test for fresh and deactivated catalysts. We propose a test to be carried out in a fixed-bed reactor at 500 °C with online analysis of products. Simple parameters are defined to classify products of side-chain cracking, ring-opening, and hydrogen-transfer (HT) reactions. Fresh zeolites (H-ZSM-5, H-Beta and H-USY) were tested. Their performances were consistent with their characteristics: the H-ZSM-5 showed the lowest activity and gave mainly cracked products from side-chain cracking. H-Beta and H-USY gave products from both side-chain cracking and ring-opening. H-USY was more active to HT, yielding more aromatics compared to H-Beta. The advantage of the model testing was demonstrated using deactivated USY and also equilibrium FCC catalysts (E-Cats). The nC4CyC6 test was sensitive to deactivated USY and showed 20-fold higher activity than n-hexane cracking. The results of the activity and hydrogen transfer capacity of 2 E-Cats revealed by the model nC4CyC6 test showed the same tendency obtained from the micro-activity test with real feed. Hence, this new model test has good potential for practical screening of FCC catalysts.