Application of ferrierite zeolite in high-olefin catalytic cracking
The potential use of pure ferrierite (H-FER) or H-FER/H-ZSM-5 blends in catalytic cracking to enhance the production of light olefins was evaluated in the catalytic cracking of n-hexane at 500 °C and the high-olefin catalytic cracking (HOCC) of a Brazilian gasoil feedstock at 600 °C. For the n-hexane cracking evaluation, only pure zeolites were employed. For the HOCC testing, both pure zeolites and the H-FER/H-ZSM-5 blends were mixed with a reference commercial FCC equilibrium catalyst to give a total zeolite content ranging from 0.5 to 8 wt.%. In both catalytic tests, the use of ferrierite resulted in the improvement of olefin production. The H-FER zeolite exhibited higher propylene and butene selectivities than H-ZSM-5. Conversely, H-ZSM-5 resulted in higher ethylene selectivity. In the HOCC tests, pure H-ZSM-5 exhibited higher ethylene and propylene yields than H-FER. However, the use of the H-ZSM-5/H-FER blends caused higher yields of the total amount of light olefins (ethylene, propylene and C4 olefins) than when only pure H-ZSM-5 zeolite was employed. This synergetic effect of the combination of the H-FER and H-ZSM-5 zeolites is reported for the first time in the literature and can be explained by taking into account the fact that the H-FER zeolite has a lower hydrogen transfer ability.