Intensifying gasoline production in the hydrocracking of pre-hydrotreated light cycle oil by means of Pt and Pd supported on a spent FCC catalyst

Abstract

Motivated by the necessity of intensifying the valorization of secondary refinery streams and of extending the life cycle of the catalysts, this study aims to obtain high quality gasoline in the hydrocracking of a pre-hydrotreated light cycle oil (HT-LCO) using noble metals catalysts supported on a spent fluid catalytic cracking (FCC) catalyst. Hydrocracking runs have been carried out in a fixed bed reactor with two different catalysts (Pt/FCC and Pd/FCC) under the following conditions: 320–400 °C; 80 bar; hydrogen to HT-LCO ratio, 1000 NmL mL−1; weight hourly space velocity (WHSV), 4.48 h−1; and time on stream (TOS), 8 h. The results have exposed that 400 °C is the optimal temperature for hydrocracking the HT-LCO, since the yield of gasoline is clearly maximized (yielding up to 80 wt%) at the same time that the formation of gases is minimized. Comparing both catalysts, the Pt/FCC catalyst has offered better performance as its high hydrogenation capacity has allowed for obtaining an isoparaffinic gasoline fraction with a RON of 93.0. These good results lay on two facts that avoid the blocking of the micropores of the zeolite HY by the deposition of coke: (i) the hydrocracking of the coke precursors; and (ii) the matrix of the FCC catalyst where a fraction of the coke is deposited. In this way, after an initial deactivation period, the catalysts have reached a pseudo-stable state with a notorious remaining catalytic activity (higher for the Pt/FCC catalyst).