Solid-Acid Catalytic Conversion of Oil Shale: Effects of Sulfonic Acid Grafting on Oil Yield Enhancing and Quality Improvement.

Oil shale is a promising unconventional resource and in situ upgrading technology has been a practical approach for enhancing oil and gas recovery. Mineral-based clin/SBA-15 has been prepared and subsequently functionalized to get SOH-SBA-15 catalysts. Compared with the noncatalytic conversion of oil shale under subcritical water, sulfonic acid grafted catalysts have played a predominant role in enhancing the oil yield by 3-16% and improving oil qualities. The O/C atomic ratio was declined to 0.10-0.11, while the hydrocarbon yield was sharply increased to 47-60% from 34%. The energy recovery has been elevated to 75-82%, and the produced oil had a heating value of 35-37 MJ/kg. Compared with that without catalyst, the energy recovery rate is 34.55%, and the heating value is 23.61 MJ/kg. The overall oil yield showed a linear trend with respect to the medium and strong acid amounts on SOH-SBA-15 in the aqueous conversion of oil shale. It was indicated that the SOH- group assisted in the depolymerization via the C-C and C-O bond breaking. Upon the addition of SOH-SBA-15, the activation energies of the oil shale catalytic conversation are decreased dramatically to 78 kJ/mol. It provided a practical approach for the in situ upgrading of oil shale under milder reaction conditions.