Medium severity hydrotreating and hydrocracking of Israeli shale oil: III. Hydrocracking of hydrotreated shale oil and its atmospheric residue for full conversion to motor fuels

Abstract

Hydrocracking of hydrotreated Israeli shale oil and its atmospheric residue was studied at 50 atm hydrogen pressure, LHSV 0.5–4.4 h −1, temperature 350°C and V H2 1500 Nl/l in a fixed bed reactor pilot plant with two Ni–Mo–zeolite catalysts based on mono-(HY+Al 2O 3) and bizeolite (HY+H–ZSM–5+Al 2O 3) supports. Desulfurization and denitrogenation conversion of the feedstock was higher than 99.7% (sulfur content 134 ppm, nitrogen content 4.4 ppm) and it comprised 14 vol.% atmospheric residue boiling out at 360°C+. Hydrocracking of the whole hydrotreated shale oil yielded full conversion of atmospheric residue at LHSV=2.75 h −1 with monozeolite catalyst (A) and at LHSV=3.5 h −1 with biozeolite catalyst (B). The yield of liquid fuel at these conditions was 87.6 wt% with catalyst A versus 82.4 wt% with catalyst B. The contents of light naphtha (<100°C), heavy naphtha (<200°C) and jet fuel (160–280°C) in the liquid product were 10–15% higher with catalyst B compared with A. Hydrocracking at full residue conversion produced shifts of the hydrocarbon distributions to lighter molecules inside the hydrocarbon groups, decreased n-paraffins concentrations by isomerization and splitting to C 5-. Hydrocracking of the atmospheric residue with catalyst A yielded full conversion into 360°C-products at LHSV=0.5 h −1. The only liquid product obtained in this case at 72.3% yield was naphtha with distillation patterns corresponding to gasoline specification. The nitrogen content in the liquid hydrocracking products at full conversion of atmospheric residue fraction of the shale oil was <1 ppm and the sulfur content <15 ppm.