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Four different samples of pure scheelite α-Bi2Mo3O12 were synthesized by the fast microwave-assisted hydrothermal method. By adjusting the pH in the preparation process, the morphologies and structures of the synthesized catalysts were changed. TG, XRD, SEM, TEM, BET, and XPS analyses were used to investigate the characteristics of the catalyst. The sample of α-Bi2Mo3O12 was prepared at a calcination temperature of 500 °C and pH = 1 had the highest specific surface area propylene selective oxidation properties. The conversion of propylene was 28.3% and the selectivity of acrolein was 86.4%. Compared with α-Bi2Mo3O12 prepared by co-precipitation and normal hydrothermal method, α-Bi2Mo3O12 prepared by microwave hydrothermal method has higher propylene oxidizing activity. The conversion of propylene is negatively correlated with the crystallinity of the catalyst. This is due to the fact that higher crystallinity inhibits the lattice oxygen flow between the lattices, thus inhibiting the selective oxidation and reducing the conversion of the reaction. The oxygen mobility of α-Bi2Mo3O12 samples was characterized by XPS. The results showed that the conversion of propylene of α-Bi2Mo3O12 were positively correlated with its oxygen mobility strength. A probable mechanism for the selective oxidation of propylene was proposed. This work not only offers a high-efficiency method for the rapid preparation of bismuth molybdate catalysts but also extends the application of microwave-assisted hydrothermal synthesis in the field of selective oxidation of propylene. [ABSTRACT FROM AUTHOR]

Multi-stage mild co-carbonization of different fluidized catalytic cracking slurry oil narrow fractions was investigated. The characteristics of cokes derived from mild co-carbonization were found to be better than those from rapid co-carbonization. The improvement in quality of cokes derived from mild co-carbonization was reflected in every stage compared to carbonization of a single fraction. Further study revealed that transferable hydrogens can be released at every stage of mild carbonization and that more transferable hydrogens can be released from combined fraction (from 10.7 mg/g to 2.7 mg/g) than a single fraction (from 10.6 mg/g to 2.9 mg/g). These transferable hydrogens can stabilize the carbonization system, thus leading to better carbonization performance of combined narrow fractions. [ABSTRACT FROM AUTHOR]

Hydrogen type ZSM-5 (HZ) and three supported NiMo catalysts (NiMoNaZ, NiMoHZ and NiMoMMHZ) prepared by incipient wetness impregnation method were systematically characterized and evaluated using 1,3,5-trimethylbenzene (1,3,5-TMB) as the model compound for heavy aromatic hydrodealkylation (HDAK). Among four catalysts, NiMoNaZ has the lowest HDAK activity; compared to HZ and NiMoHZ, NiMoMMHZ has superior 1,3,5-TMB HDAK performance. The characterization results demonstrate that suitable acidity and mesopores of MMHZ result in appropriate metal–support interaction and benefit formation and dispersion of Mo/Ni species in proximity to acid sites on NiMoMMHZ, thus facilitating both textural and chemical synergy between Mo/Ni and acidic sites. This not only improves hydrogenation and hydrogenolysis performance of Mo/Ni species, but facilitates cracking function of acid centers, conferring NiMoMMHZ with higher HDAK activity, selectivity and stability. The finding of this research opens a novel route of enhancing synergy effect between Mo/Ni and acid sites in zeolite supported MoNi catalysts for improving heavy aromatic HDAK performance. Synergism between Mo/Ni and acid sites on NiMo/ZSM-5 for heavy aromatic hydrodealkylation (HDAK) was revealed. [ABSTRACT FROM AUTHOR]

Phosphotungstic acid (HPW) / mesoporous zeolite (MCM-41) were prepared using different amount of HPW loaded on MCM-41 by wet impregnation. The prepared catalysts were applied in oxidation desulfurization process, and the key reaction conditions influencing dibenzothiophene (DBT) conversion were studied, including the amount of catalyst, the volume ratio of acetonitrile to model oil, and the molar ration of H2O2 to DBT. The conversion rate of DBT reached 99.8% for 40w-HPW/MCM-41 under the optimal conditions. The structures of the catalysts were characterized before and after reaction. The density functional theory (DFT) calculation clearly revealed the stepwise reaction mechanism of DBT oxidation with HPW and H2O2. The proposed reaction path is reasonable in the kinetic modeling of oxidative desulfurization using heterogeneous HPW catalysts with H2O2. [ABSTRACT FROM AUTHOR]

NiMoS supported on ZSM-5 with different Si/Al ratio, crystallite size and pore structure was prepared by incipient impregnation method and applied in 1, 3, 5-trimethylbenzene (1, 3, 5-TMB) hydrodealkylation (HDAK). The physicochemical properties of samples were characterized by XRD, FTIR, SEM, N2 adsorption–desorption, NH3-TPD, Py-FTIR, H2-TPR, HRTEM and TGA. It is demonstrated that for microporous NiMoS/ZSM-5, acid amount and crystallite size of HZSM-5 are key factors affecting HDAK performance. The larger acid amount and smaller crystallite size can promote the conversion of 1, 3, 5-TMB, especially the dealkylation reaction, resulting in higher BTX yield. Compared to NiMoZ-3, mesopores in micro-mesoporous NiMoAKZ-3 are beneficial to accessibility of 1, 3, 5-TMB to NiMoS and acid sites in close proximity, and the diffusion of reactant and product molecules inside pores, thus resulting in superior HDAK performance of NiMoAKZ-3. Moreover, the reaction network of 1, 3, 5-TMB HDAK was revealed according to product distribution. NiMoS supported on ZSM-5 was developed for heavy aromatic hydrodealkylation (HDAK). Acid amount and crystallite size of microporous ZSM-5 are key factors affecting 1,3,5-trimethylbenzene (1,3,5-TMB) HDAK. Mesopores inside ZSM-5 facilitate accessibility of 1,3,5-TMB to NiMoS and acid sites in close proximity and improve HDAK performance. [ABSTRACT FROM AUTHOR]

The effects of phosphorus on the structure and hydrofining performance of tri-metallic WMoNi/AlO catalysts prepared with W/Mo-based hybrid precursor nanocrystals were investigated. The incorporation of phosphorus weakened the metal-support interactions (MSIs) and facilitated the formation of more synergetic NiWMoS phases with higher stacks. Catalytic tests using a fluid catalytic cracking diesel fuel showed that the changes in the MSIs and the morphology of the active phases had a more positive effect on the hydrodenitrogenation activity than on the hydrodesulfurization activity. In contrast, when phosphorus was incorporated into a tri-metallic WMoNiP/ AlO catalyst prepared by a conventional incipient impregnation method, the MSIs decreased causing aggregation of the metal species which resulted in poorer hydrofining performance of the catalyst. These results show that incorporating phosphorus into a WMoNi/AlO catalyst can finely tune the structure of the active phase to enhance the hydrogenation and hydrodenitrogenation activity of the resulting tri-metallic catalyst. [ABSTRACT FROM AUTHOR]