We report on the deposition of thin nanolayers of MoS2 material on carbon nanofibers (CNFs) and multiwalled carbon nanotubes (CNTs) by in situ thermal decomposition of (NH4)2MoS4 in oleylamine. The synthesized MoS2@CNF and MoS2@CNT nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and Raman spectroscopy. TEM results indicate that CNFs, as well as CNTs, provide an excellent template for the deposition and growth of MoS2 nanolayers. 2–5 layers thick MoS2 nanocrystals and 5–10 nm wide form on the CNFs, while monolayers of the same width form on the CNTs. The advantage of the applied synthetic method is that it provides control over the material morphology, leading to uniform and full cover of the CNFs and CNTs with no individual formations of material away from the carbon. To the best of our knowledge, the deposition of MoS2 on CNFs has not been reported elsewhere.

Hydrodesulfurization (HDS) of crude oil plays a vital role in the refining of petroleum products. With ever-increasing regulations restricting the allowable concentrations of sulfur in fuel, further research is required to produce more efficient and effective catalysts. Herein, we have synthesized carbon nanotube (CNT)-supported cobalt-molybdenum (CoMo) catalysts for HDS of dibenzothiophene (DBT) via Co-first and Mo-first sequential impregnation as well as co-impregnation. Spectroscopic analysis shows the formation of a CoMo catalyst with no free sulfided Co phase present. Additionally, CoMo catalysts are found to be predominantly single-layered nanocatalysts layered on the CNT support. Temperature-programmed reduction (TPR) measurements show differences in reducing temperature of the sulfided CoMo catalysts prepared by the different methods, but catalyst activities for HDS of DBT did not fully align with the TPR-predicted order. Thus, provided the reaction temperature is high enough, reducibility may not always be an adequate gauge of catalytic activity. Conversion of DBT was highest in Mo-first sequential impregnation (81.5%), followed by co-impregnation (64%) and Co-first sequential impregnation (60%) on a CNT support. While these results contrast with some others regarding the order of impregnation, we propose that the preferred impregnation order is actually support-dependent, rather than an absolute quality.

Coiled screen or Sulzer CY gauze structured packings, loaded with an activated carbon treated to make it partially hydrophobic, were employed to investigate the removal of SO2 from a stack gas. Measurements were made of SO2 removal and its conversion to H2SO4 and gas-side pressure drop as a function of gas and liquid loadings, temperature, and method of operation (continuous liquid flow vs intermittent liquid flow). Both packings exhibited remarkably high catalytic efficiency in terms of SO2 converted per gram of carbon, as well as high conversions of SO2 to H2SO4 and low-pressure drops. Although the Sulzer CY packing displayed the lowest pressure drop per meter of packing depth, the coiled screen provided higher removal of SO2 per volume of packing. The performances of each were close enough that a choice between them would require an economic analysis.

ctivated carbon has been known as an effective catalyst for SO, oxidation for many years (Hartman and Coughlin, 1972). Haure A et al. (1989) found that the productivity of some activated carbons at room temperature was comparable with commercial catalysts such as V,O, or platinum for the oxidation of SO, . Since the Hartman and Coughlin work, there have been several laboratory studies of scrubbing SO, from stack gas and converting this waste t o sulfuric acid.Indeed, several commercial processes have been proposed. Early work was done using activated carbon in the form of pellets in trickle-bed reactors washed with water as a flushing agent. Two problems arise: pressure drops in packed beds are too large for the process to be attractive industrially, and washing with water results in a dilute acid that is impossible to market. Our research team at University of Waterloo has explored using periodic flushing of the TBR to increase SO, removal and productivity per unit weight of carbon (Metzinger et al., 1994; Haure et al., 1989; Lee et al., 1995). A concentrated acid could not be made, however. Vladea et al. (1 997) found that using activated carbon coated onto a structured packing employing a hydrophobic binder provides high SO, removal and high carbon productivity with just a small pressure drop. This work continues these studies.Our principal objective was thus to examine the use of moderately polar organic solvents such as the ketones as the scrubbing or flushing agent in a carbon packed TBR in place of water. Most solvents exhibit much lower hydrogen bonding in the liquid phase than water and so may be evaporated from a solution at a relatively low energy input. If sufficient water is present along with SO, and 0 , in the gas phase to form sulfuric acid on the activated carbon surface, evaporation of the solvent would release a concentrated acid product. A key consideration is the solubility of sulfuric acid in polar organic solvents. In recent work, we have discovered that sulfuric acid as well as SO, and 0 , are soluble in the ketone solvents (Won et al., 2000).Ketones were chosen as the polar organic solvents for our study. The lowest molecular weight ketone, acetone, exhibits relatively high solubility for oxygen and SO, at room temperature. The solubility of oxygen in acetone at 20°C is almost tenfold greater than in water. SO, is sixfold more soluble in acetone than in water. Since the trickle bed in this study is operated near room 'Author to whom correspondence may be addressed: E-mail address: rhudgins@ cape Experiments were carried out on the performance of several ketone solvents for the scrubbing of dilute SO, from a gas stream and its conversion to sulfuric acid in a trickle-bed reactor packed with activated carbon. Using a bench-scale trickle bed packed with a structured packing based on Sulzer static mixers coated with CentaurTM activated carbon and a Teflon binder, measurements of SO, removal, conversion to acid and catalyst productivity showed that all were considerably greater than levels a...

Background: Molybdenum sulfide (MoS 2 ) catalysts to be used for hydrodesulfurization (HDS) processes were prepared via the reductive thermal decomposition of ammonium tetrathiomolybdate at fixed temperature (653 K) by varying decomposition times and H 2 pressures. Both parameters were found to strongly influence textural and catalytic properties of the resulting MoS 2 catalysts.