Display omitted
•Vacuum residue hydrocracking follows parallel reaction pathways to form liquid oils, gas, and coke.•During hydrocracking, the oil-soluble Mo precursor is transformed into a nano-MoS2 ...catalyst.•Dispersed MoS2 catalyst enhanced vacuum residue hydrocracking with liquid oils to over 90%.
The slurry phase hydrocracking (HCK) of vacuum residue (VR) in the presence of dispersed MoS2 catalyst was investigated under varying temperature, pressure, and reaction time. Extended X-ray absorption fine structure (EXAFS) measurements were used to obtain structural information about the dispersed MoS2 phase during the reaction. Under a standard reaction condition of temperature 673K and pressure 10.0MPa in an autoclave batch reactor, kinetic analysis for VR HCK confirmed that the reaction occurs in a parallel manner in the production of 77% liquid oils as major products such as vacuum gas oil and distillates with the generation of gas and of 23% coke in the presence of dispersed MoS2 catalyst (0.113mmol or 360ppm Mo). Although temperatures below 653K at 9.5MPa were found beneficial in coke reduction to less than 1.0wt.% in favor of hydrogenation at 33h of reaction, higher pressures over 15MPa at 673K were more influential in accelerating the VR conversion into liquid products, reaching 90% at 4h of reaction with coke reduction down to 1.2wt.% than the cases under conditions below 10MPa. Analysis of the spent catalysts by EXAFS and TEM demonstrated that the nanosized MoS2 phase was well developed from Mo(CO)6 in the early stage of the reaction, with lower MoS and MoMo coordination verifying the small MoS2 particles having more exposed and defect sites as active phases.
Display omitted
•Different shapes of oil-dispersed MoS2 were obtained by a ligand stabilization method.•Monoslab MoS2 showed higher activity in vacuum residue hydrocracking than multilayered ...MoS2.•The vacuum residue hydrocracking activity of MoS2 catalysts was well correlated with the rim-site model.
Different morphologies of oil-dispersed MoS2 catalysts were obtained by a ligand stabilization method using Mo(CO)6 as a Mo precursor and trioctylphosphine oxide (TOPO) as a coordinating agent to identify the active site of MoS2 in the hydrocracking (HCK) of vacuum residue (VR). Transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to obtain structural properties of the dispersed catalyst. It was observed that the MoS2 forms a nanoscaled monolayer from 5 to 10 nm in size. The effect of the oil-dispersed MoS2 catalysts having different morphology on the slurry phase HCK of VR was investigated at 673 K and 9.5 MPa H2. The turnover frequency (TOF) of the dispersed MoS2 catalysts in the VR HCK was found to show a good correlation with the rim-site Mo dispersion of the MoS2 slabs based on the same metal loading of 0.113 mmol at 673 K and 9.5 MPa H2.
Display omitted
•In the hydrocracking of vacuum residue, Ni, Co, or Mo precursor forms nanoscaled sulfides of 5–20 nm.•Oil dispersibility affects the hydrocracking of vacuum residue, following the ...order MoS2 > Co9S8 ≫ Ni3S2.•Among Mo precursors, Mo-octoate having an intermediate oxidation state shows better activity than others.
The effects of Co, Ni, or Mo precursors having different oil solubility and oxidation state on the slurry phase hydrocracking (HCK) of vacuum residue (VR) was investigated at 673 K and 9.5 MPa H2. X-ray diffraction and extended X-ray absorption fine structure spectroscopy were used to obtain structural properties of the dispersed catalyst. Under standard operating condition, the metal precursors were found to form nanoscaled dispersed particles of MoS2, Co9S8, and Ni3S2, with the following VR HCK performances in the order MoS2 > Co9S8 ≫ Ni3S2, based on the same metal loading of 0.113 mmol. Among the oil-soluble Mo precursors such as Mo-hexacarbonyl, -octoate, and -naphthenate, it was observed that Mo-octoate having an intermediate oxidation state forms the smallest particles of 5.8 nm in size and shows the best activity in the VR HCK.
Display omitted
•Oil-dispersed CoWS2 catalysts of 7–10 nm were prepared in situ in VR HCK.•CoWS2 catalysts showed better activity and stability than Co9S8 or WS2.•Formation of Co-WS2 phase was ...confirmed by the Co K-edge XANES analysis.
The bimetallic CoWS2 catalysts were prepared in situ during the slurry phase hydrocracking (HCK) of vacuum residue (VR) using W(CO)6 and Co-octoate as oil soluble precursors to investigate the promotional effect of Co promoters on the dispersed WS2 catalyst for the VR HCK. The morphologies and structural properties of dispersed catalysts were characterized by transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). The bimetallic CoWS2 catalyst was observed to form well-dispersed monolayers in the size range of 7–11 nm, which showed higher turn-over frequency values (TOF) and C7-asphaltene (C7-ASP) conversions than monometallic WS2 or Co9S8 catalysts in the VR HCK at 693 K and 10.0 MPa H2. Moreover, the extended X-ray fine absorption structure spectroscopy (EXAFS) coupled with the density functional theory (DFT) calculations successfully verified the formation of the Co-W-S phase.
Display omitted
•XANES analysis confirmed transformation of VO-porphyrin into V2S3 in hydrocracking.•V2S3 formed from VO-porphyrins was active in the hydrocracking of vacuum residue.•Carbon black has ...a beneficial effect on the dispersion of the V2S3 catalysts.
The asphaltene hydrocracking (HCK) was carried out at 693 K and 11.0 MPa H2 to examine the phase transformation of V species contained in the asphaltene and the catalytic activity of the resulting V compounds in the HCK. The V K-edge X-ray absorption near edge structure spectroscopy (XANES) was employed to identify the V species dispersed in the asphaltene and the phase transformation with respect to the HCK conditions. The V in asphaltene was observed as a form of the vanadyl-porphyrins (VO-porphyrin) that was converted into V2S3 during the HCK in the presence of tetralin, whereas the VO-porphyrin was not converted fully into the V2S3 in the absence of tetralin due to its isolation within a coke. In addition, the catalytic activity of V2S3 formed from VO-porphyrins in the asphaltene was confirmed by an increase of H2 consumption and asphaltene conversion in the recycle tests of the vacuum residue (VR) HCK at 693 K and 11.0 MPa H2 in the presence of tetralin. The intrinsic catalytic activity of the dispersed V2S3 in the VR HCK was measured at 693 K and 11.0 MPa H2 in presence of the model V precursor of 0.113 mmol VO(acac)2, exhibiting a TOFT of 0.080 s−1 and the asphaltene conversion of 30%. The XANES and TEM analysis confirmed that the V precursor undergoes transformation into nano-scaled V2S3 particles in course of the VR HCK. Therefore, it was demonstrated that the VO-porphyrin in asphaltenes can be converted into the dispersed V2S3 catalysts during the VR HCK.
Display omitted
•Tetralin as an H-donor promotes the reactivity of asphaltenes.•Tetralin reduces coke and gas formation in hydrocracking of pitch.•Dispersed MoS2 catalyst coupled with H-donor ...improves pitch HCK performance.
The effects of tetralin as an H-donor on the reactivity of asphaltenes in a petroleum pitch were investigated under thermal cracking or catalytic hydrocracking conditions at 693 K and 10.0 MPa N2 or H2. Reaction temperatures, pressures, and tetralin contents were varied to examine the reactivity of asphaltenes. Thermal cracking of the petroleum pitch led to a considerable amount of coke formation, close to 53.7 wt%, but the addition of tetralin reduced the coke formation down to 23.6 wt%. The coke formation was considerably reduced to 10.3 wt% in the catalytic hydrocracking condition, and was not formed in the presence of tetralin. Kinetic studies on the catalytic hydrocracking of petroleum pitch in the absence or presence of tetralin demonstrated that the addition of tetralin, showing an increase in the hydrogen transfer capacity, contribute to the marked performance of hydrocracking of the petroleum pitch in the presence of dispersed MoS2 catalyst.
Diverse nanosystems for use in cancer imaging and therapy have been designed and their clinical applications have been assessed. Among a variety of materials available to fabricate nanosystems, ...poly(lactic-
-glycolic acid) (PLGA) has been widely used due to its biocompatibility and biodegradability. In order to provide tumor-targeting and diagnostic properties, PLGA or PLGA nanoparticles (NPs) can be modified with other functional materials. Hydrophobic or hydrophilic therapeutic cargos can be placed in the internal space or adsorbed onto the surface of PLGA NPs. Protocols for the fabrication of PLGA-based NPs for cancer imaging and therapy are already well established. Moreover, the biocompatibility and biodegradability of PLGA may elevate its feasibility for clinical application in injection formulations. Size-controlled NP's properties and ligand-receptor interactions may provide passive and active tumor-targeting abilities, respectively, after intravenous administration. Additionally, the introduction of several imaging modalities to PLGA-based NPs can enable drug delivery guided by in vivo imaging. Versatile platform technology of PLGA-based NPs can be applied to the delivery of small chemicals, peptides, proteins, and nucleic acids for use in cancer therapy. This review describes recent findings and insights into the development of tumor-targeted PLGA-based NPs for use of cancer imaging and therapy.
Display omitted
•Oil-dispersed CoMoS2 catalysts of 5–7 nm in size were successfully prepared in situ in the VR HCK.•CoMoS2 catalysts showed better activity than monometallic MoS2 or Co9S8 ...catalysts.•Formation of the Co–Mo–S phase was confirmed by Co K-edge XANES and Mo K-edge EXAFS analysis.
Unsupported bimetallic sulfide catalysts were obtained in situ using Mo(CO)6 and Co octoate as precursors to investigate the promotional effect of Co on the MoS2 catalyst in the hydrocracking (HCK) of vacuum residue (VR). Transmission electron microscopy (TEM) and X-ray absorption fine structure spectroscopy were used to obtain structural properties of the catalysts. The bimetallic CoMoS2 catalyst exhibited high catalytic activity in the VR HCK with respect to the H2 consumption rate and asphaltene conversion as compared with monometallic sulfides such as Co9S8 or MoS2 with the same catalyst loading of 0.113 mmol at 673 K and 9.5 MPa H2. Higher hydrodesulfurization activity was also observed for the CoMoS2 catalyst. Moreover, extended X-ray absorption fine structure and TEM analysis identified the formation of a Co–Mo–S phase in monoslab particles of average particle size 6.7 nm and the maintenance of the morphology during five times of recycle tests. These results thus suggest that the unsupported CoMoS2 catalyst has a promotional effect on VR HCK.
Display omitted
•Oil-dispersed MoS2 catalysts of 4.8 nm in size were obtained in situ with carbon black (CB) as additives in VR HCK.•MoS2-CB showed better activity than MoS2 or commercial catalysts ...in regard to the C7-ASP conversion and H2 consumption rate for VR HCK.•MoS2-CB maintained stable and high activity in the recycle runs of VR HCK.
Effects of carbon black (CB) additives with dispersed MoS2 catalysts (d-MoS2) on the slurry phase hydrocracking (HCK) of vacuum residue (VR) were studied in an autoclave batch reactor at 693 K and 9.5 MPa H2. For comparison, commercial NiMo catalysts supported on large and small pore volume Al2O3 (-LP, -SP) were also applied for the VR HCK. The structure of the catalysts was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS). The dispersed MoS2 (d-MoS2) was observed to form nanosized single slabs of 8.4 nm, while in the presence of CB the particle size of the d-MoS2-CB became even smaller (4.8 nm). A series of recycle runs of the VR HCK revealed high activity and stability of d-MoS2-CB followed by d-MoS2 > NiMo-LP > NiMo-SP. The kinetic analysis also demonstrated that the d-MoS2-CB shows a high asphaltene conversion with minimizing coke formation.
PDF
