Thermal hydrocracking and slurry-phase hydrocracking of Karamay vacuum residue (KLVR) were studied, and the hydrocracked products were analyzed by gas chromatography (GC) and a paraffins, olefins, naphthalenes, and aromatics (PONA) composition analysis system. The effects of the temperature and initial hydrogen pressure on the isomerization reaction in heavy oil slurry-phase hydrocracking were investigated. Experimental data revealed that the conversion of KLVR increased as the temperature and initial hydrogen pressure increased in both thermal hydrocracking and slurry-phase hydrocracking. Hydrogen consumption of slurry-phase hydrocracking increased with the increase of the temperature and initial hydrogen pressure, while hydrogen consumption in thermal hydrocracking was negligible. Two impact indexes R G ′ and R N ′ were proposed to study the isomerization reaction in heavy oil slurry-phase hydrocracking. The results indicated that a high temperature and high initial hydrogen pressure enhanced the isoparaffin restraining effect of a dispersed Mo catalyst. Under a certain reaction temperature, the linear relation between impact indexes and hydrogen consumption was observed, indicating that the isomerization reaction was inhibited by hydrogen participating in a free-radical reaction.

Titania (TiO 2 )-supported gold (Au) nanoparticles (NPs) have long been considered as a promising solution for carbon monoxide (CO) poisoning in proton exchange membrane fuel cells (PEMFCs) as they can efficiently catalyze CO oxidation reaction. Nevertheless, the actual application in functioning PEMFCs has been rarely reported primarily due to the challenges of synthesizing and incorporating the oxidation catalyst in manners compatible with the structure and fabrication of PEMFCs. Here we successfully incorporate the Au NPs/TiO 2 catalyst into PEMFCs and demonstrate an excellent CO elimination function, improving the performance and CO tolerance of PEMFCs; we combine an ultrathin TiO 2 layer (<1 nm) deposited on a Nafion membrane via the low-temperature atomic layer deposition (ALD) and a monolayer of Au NPs assembled on the top of the ultrathin TiO 2 using the Langmuir−Blodgett method. An over 30% enhanced maximum power output is achieved under the presence of a trace amount of CO. Even under highly concentrated CO (0.1%), a less than 10% performance decrease occurs with the incorporation of Au NPs/TiO 2 , in contrast to a nearly 70% performance decrease observed in the control device. The results represent the first experimental implementation of Au NPs/TiO 2 catalysts in PEMFCs and the confirmation of their effectiveness for mitigating the CO poisoning effect.

The composition, structure, and colloidal stability of hydrocracked products at various hydrogen pressures were analyzed to investigate the role of hydrogen pressure in slurry-phase hydrocracking of Venezuela heavy oil. Experimental data showed that the formation of gas, naphtha, and coke was suppressed by a high hydrogen pressure during the slurry-phase hydrocracking. In addition, the maximum of light oil per coke ratio was observed at 8 MPa of hydrogen. The desulfurization and denitrogenation were promoted by the increase of hydrogen pressure. However, the influence of hydrogen pressure on the desulfurization rate was reduced at higher pressure, while the influence on the denitrogenation rate was still obvious. With the increase of hydrogen pressure, the Conradson carbon residue (CCR) of the vacuum residue (VR) product decreased. Meanwhile, the coking inducing period of the atmospheric residue (AR) product prolonged, which means that the colloidal stability of the AR product was enhanced by a high hydrogen pressure. Structural parameters of asphaltene were studied according to the reference of the Fourier transform infrared (FTIR) spectroscopy method of kerogen structure studying. The cracking and hydrogenation saturation of asphaltene were promoted by a high hydrogen pressure, which lead to the increase of the A factor (infrared absorption intensity ratio of saturated aliphatic carbon and aromatic carbon) and n CH 2 /n CH 3 of asphaltene products as well as the decrease of the Y factor (condensation index of asphaltene) and Z factor (discriminative index of the side-chain fracture situation of asphaltene).

Two feedstocks (LPA and HPA) obtained from modification of naphthenic vacuum residues were selected to prepare mesophase pitch by direct thermal treatment. The influence of reaction temperature, soaking time, reaction pressure, and molecular structures of the feedstock on mesophase development was systematically investigated by analyzing variations in carbonization yield, carbon residue, quinoline insolubles (QI) content, density, optical textures, crystal structure, and surface morphology of derived products. It is found that the mesophase development and the properties of resultant mesophase products were closely related to the molecular structure of the original materials and preparation conditions. Compared with LPA, HPA was the preferable feedstock for thermal treatment because of its high degree of aromaticity and a large proportion of naphthenic carbon, and the resultant product obtained under the optimum conditions showed large flow domain mesophase, fewer alkyl side chains, and a high degree of molecular orientation.

No abstract