Catalytic desulfurization of a model sulfur-containing compound benzothiophene (BT) through partial oxidation in supercritical water (SCW) was investigated in a bomb reactor at 623-723K and 30-40MPa over sulfided CoMo/-Al2O3. Vacuum residuum was used to confirm the desulfurization rate and efficiency, and the desulfurization mechanism of vacuum residuum was determined by the pyrolysis temperature (TR) of the vacuum residuum (VR). For T>TR, obvious reduction of sulfides up to 67% was obtained. The thermodynamic equilibrium of in situ H2 generation was a controlling factor of the desulfurization pathway.

Five models for fishbone-type carbon nanofibers (f-CNFs) have been proposed and their geometries have been optimized through molecular dynamics and molecular mechanics simulations. The angle between graphene layers and fiber axis can take the values 9.71, 19.60, 30.03, 41.99, and 56.43, which agree satisfactorily with the experimentally determined values. With reduction of the angle, the interlayer spacing of graphene sheets increases from 0.3376nm to 0.3392nm accordingly, due to the strain of the graphitic cones. In addition, X-ray diffraction (XRD) simulations are also implemented. With the high-resolution transmission electron microscopy (HRTEM) results taken into account, the XRDsimulations verify that f-CNFs can adopt not only a regular arrangement but also a turbostratic way, and our models are good approximations for describing the bulk microstructures of f-CNFs.

Electrosynthesis of glyoxylic acidby electroreduction of oxalic acidhas long been well known. However, attempts to commercialize the process have encountered problems due to rapid deactivation of the cathode. The cathode activity can be continuously restored by adding small amounts of chemical activators to the catholyte. In this paper the structural e5ect of chemical activator on electrode reaction is studied. The results show that (1) It is the cation of the chemical activator, but not the anion that a5ects the current e6ciency and the reaction selectivity. (2) The more symmetrical the cation, or the shorter the longest alkyl chain, the higher the current e6ciency and the reaction selectivity become. (3) Mechanism of the activation is discussed. Adsorption of the cations of the activator on the cathode surface protects the electrode. (4) Quantitative characterization of the activator molecule is given using some topological indices, with which the activation ability can be predicted, and screening of the proper activator is made possible.

The work reported in this paper aimed at exploring the advantages of using supercritical carbon dioxide (scCO2) as an environmentally benign solvent and swelling agent for carrying out the grafting process of maleic anhydride onto polypropylene in the solid state. The effects of scCO2 on the melting temperature and melting enthalpy of an isotactic polypropylene (iPP) were investigated first in order to define the upper reaction temperature and CO2 pressure limits. The effects of various factors on the grafted anhydride content and on changes in the molecularscale and microscale structures of the resulting iPP were then investigated. Those factors included the reaction time, monomer and initiator concentrations, reaction temperature, CO2 pressure, and size of the iPP particles. Results showed that the scCO2-assisted solid-state grafting process of maleic anhydride onto iPP did have some scientifically interesting and industrially relevant advantages over the classical solid-state or melt process. Among them, it is worth pointing out that the CO2 pressure itself constituted an additional and sensitive process parameter capable of significantly modifying the overall reaction pathway and the product quality. For example, without CO2, the solid-state grafting process was diffusion-controlled. Under scCO2, it became reaction-controlled. The CO2 pressure could also regulate the anhydride content with ease. On the other hand, the degree of iPP chain scission was not reduced under scCO2 compared to that of the classical melt process.

The impact of some engineering aspects such as space velocity, catalyst metal loading, hydrogen, and temperature on carbon nanotube (CNT) production rate, productivity, and morphology in carbon monoxide disproportionation has been studied. The morphology and quality of the CNTs produced were examined by high resolution transmission electron microscopy (TEM). It was found that space velocity and metal loading have significant effects on the production rate and CNT productivity. The presence of H2 dramatically increased the productivity, but altered the CNT structure. The synthesis temperature also influenced the carbon productivity and structure. The results were interpreted according to the traditional model for CNT growth, and the implications for large-scale CNT production were suggested.