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.

Novel dendritic micro-mesoporous TS-1/dendritic mesoporous silica nanoparticles (DMSNs) composites (TD) were assembled by TS-1 nanocrystals with ultrasmall particle size and strong acidity. TS-1 seeds and DMSNs were composited via the Ti-O-Si chemical bond, which stimulate on the generation of Brønsted (B) and Lewis (L) acid. The spillover d-electrons produced by The Ti element of TS-1 seeds produced a spillover of d-electrons, which could interact with the surface of MoS 2 phases, thereby reducing Mo-S interactions and creat sulfur vacancies that are favorable for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) hydrodesulfurization (HDS) reactions. The increased B&L acid amount of NiMo/TD-2.0 with Cetyltrimethylammonium bromide/Sodium salicylate molar ratio of 2.0 played a important role in facilitating the hydrogenation (HYD)route of DBT HDS and the isomerization (ISO) route of 4,6-DMDBT HDS, which is more favorable to the reduction of steric hindrance of DBT and 4,6-DMDBT reactants in the HDS reaction process. The NiMo/TD-2.0 catalyst exhibited the highest turn-over frequency (TOF) value and HDS reaction rate constant (k HDS ) of DBT and 4,6-DMDBT due to its ultrasmall particle size, uniform spherical dendritic morphology, strong B&L acidities and good stacking degree.

Dendritic mesoporous silica nanospheres (DMSNs) with center-radical pore structure were successfully fabricated with ZSM-5 seeds to synthesize hierarchically meso-microporous ZSM-5/DMSN (ZD) materials, which were used as the support for preparing HDS catalysts. The catalytic activities were evaluated by adopting DBT as the model oil. ZD composites and the corresponding catalysts were well characterized by XRD, XPS, HRTEM and other techniques. The characterization results manifested that the specific center-radical pore structure was retained after the incorporation of microporous zeolite ZSM-5, thus ZD exhibited a wide pore diameter about 17 nm, which was definitely preferable for mass transfer in S removal process. Meantime, the open pore channels enhanced the accessibility of active sites on the internal surface of catalysts. The introducing of ZSM-5 seeds into the framework of DMSNs also improved the acidity and modulated the metal-support interaction as well. As a result, NiMo/ZD series catalysts demonstrated high HDS activities, of which NiMo/ZD-3 achieved the highest HDS efficiency of 98.3%. The superior catalytic performance not only originated from the large center-radical pore structure and good acidity of support, but also related to the suitable metalsupport interaction and perfect dispersion of metallic active sites.

A novel dendritic composite (TD) with an open center-radial pore structure using TS-1 nanocrystals as microporous precursors were synthesized successfully by a facile method. TS-1 nanocrystals were embedded into the framework of dendritic mesoporous silica nanospheres (DMSNs) to form Si-O-Ti bonds, which was beneficial to generate more S vacancies of MoS2 active phases. NiMo/TD-2 catalyst had a larger surface area and higher metal-support-interaction (MSI), resulting in a higher sulfidation and dispersion degrees of MoS2 active phases over the sulfided NiMo/TD-2 catalyst, which was consequently favored to improve the HDS activity of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Furthermore, the NiMo/TD-2 catalyst with SiO2/TiO2 molar ratio of 150 exhibited higher hydrodesulfurization (HDS) performances of DBT and 4,6-DMDBT than other NiMo/TD catalysts and the commercial NiMo/Al2O3 catalyst. Moreover, the NiMo/TD-2 catalyst possessed higher Brønsted (B) and lewis (L) acid sites, thus promoted the hydrogenation (HYD) of DBT and the isomerization (ISO) of 4,6-DMDBT.

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