Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of petroleum products and intermediates are reviewed to provide the basis for developing processes to produce gasoline and diesel oil with very low sulfur content. The reactivity, selectivity and inhibition (susceptibility of substrate molecules to inhibitors) in the catalytic process are very important to develop efficient processes. Recent advances in the understanding of active species, supports and supporting methods are also critically reviewed to suggest the design of catalysts with adequate activity to satisfy future regulations on transportation fuels. Details of the structures of the catalysts are not discussed, but the mechanisms of hydrodesulfurization and inhibition are summarized. Catalyst deactivation and reactor design are also briefly reviewed. New approaches to achieve deep hydrodesulfurization are proposed.

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Steam catalytic cracking was performed over metal modified BEA zeolite. Nickel and cobalt were introduced to the desilicated BEA zeolite by substitution treatment. The method of metal incorporation used here allowed incorporation of the metal(s) into the framework matrix of BEA in tetrahedral form together with the external surface. The successful incorporation of nickel/cobalt into the BEA framework in tetrahedral form was confirmed from FTIR spectra and UV–vis. The quantity of metals attached to BEA zeolite was calculated by EDX. The changes and defects of the BEA structure were studied from XRD patterns and SEM micrographs. The metal incorporation significantly increased the total acidity, as confirmed by NH3-TPD and pyridine FTIR analysis. The attachment of metals considerably increased the conversion of n-dodecane as compared to the parent sample. The stability of BEA zeolite was also enhanced significantly. However, the addition of Co to Ni incorporated BEA zeolite had a negative effect on both n-dodecane conversion and BEA stability.

Arabian Heavy crude oil was fractionated into distillate and vacuum residue fractions. The vacuum residue fraction was treated with supercritical water (SCW) at 450 °C in a batch reactor for 15 to 90 minutes. The main products were gas, coke, and upgraded vacuum residue; the upgraded residue consisted of gasoline, diesel, and vacuum gas oil range components. The molecular composition of gas and upgraded vacuum residue was analyzed using gas chromatography (GC, GC×GC). SCW treatment converted higher carbon number aliphatics (≥ C21) and long chain (≥ C5) alkyl aromatic compounds into C1-C20 aliphatics, C1-C10 alkylaromatics and multi-ringed species. The concentrations of gasoline and diesel range compounds were greater in the upgraded product, compared to the feed. A first-order, five lump reaction network was developed to fit the yields of gas, coke, diesel and gasoline range components obtained from SCW upgrading of vacuum residue. Distillation of crude oil followed by SCW treatment of the heavy fraction approximately doubled the yield of chemicals, gasoline, and diesel, while forming significantly less coke than conventional upgrading methods. ** Many of the results in this manuscript were presented by S. Gudiyella at the 2016 AIChE Annual Meeting, identified as the Best Presentation in the session "Reaction Engineering of Biomass and Hydrocarbons in Supercritical Water" by the Session Chair K. Choi.

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