http://w0.rz-berlin.mpg.de/hjfdb/pdf/260e.pdf

Metal deposits on well-ordered oxide films

Thiophene Hydrodesulfurization over Nickel Phosphide Catalysts: Effect of the Precursor Composition and Support

X-ray photoelectron spectroscopy and first-principles density-functional calculations were used to study the interaction of thiophene, H2S, and S2 with Ni2P(001), α-Mo2C(001), and polycrystalline MoC. In general, the reactivity of the surfaces increases following the sequence MoC < Ni2P(001) < α-Mo2C(001). At 300 K, thiophene does not adsorb on MoC. In contrast, Ni2P(001) and α-Mo2C(001) can dissociate the molecule easily. The key to establish a catalytic cycle for desulfurization is in the removal of the decomposition products of thiophene (CxHy fragments and S) from these surfaces. Our experimental and theoretical studies indicate that the rate-determining step in a hydrodesulfurization (HDS) process is the transformation of adsorbed sulfur into gaseous H2S. Ni2P is a better catalyst for HDS than Mo2C or MoC. The P sites in the phosphide play a complex and important role. First, the formation of Ni−P bonds produces a weak “ligand effect” (minor stabilization of the Ni 3d levels and a small Ni → P charge...

Desulfurization reactions on Ni2P(001) and alpha-Mo2C(001) surfaces: complex role of P and C sites.

Characterization, determination and elimination technologies for sulfur from petroleum: Toward cleaner fuel and a safe environment

Synthesis, Characterization, and Hydrodesulfurization Properties of Silica-Supported Molybdenum Phosphide Catalysts

Thiophene Hydrodesulfurization over Alumina-Supported Molybdenum Carbide and Nitride Catalysts: Adsorption Sites, Catalytic Activities, and Nature of the Active Surface

The adsorption of thiophene (C4H4S) on γ-Al2O3 has been investigated in ultrahigh vacuum (UHV) using infrared (IR) spectroscopy and temperature-programmed desorption (TPD). Following thiophene adsorption onto γ-Al2O3 at 130 K, TPD reveals two peaks with maximum rates of desorption at 175 and ∼220 K. The former peak is assigned to desorption of multilayer thiophene while the latter peak is assigned to desorption of weakly chemisorbed thiophene from the alumina surface. IR spectroscopy of adsorbed thiophene at submonolayer coverages provides further evidence that thiophene interacts only weakly with the alumina support; no decomposition of the thiophene overlayer is observed upon heating to 600 K under UHV conditions or a partial pressure of thiophene of 3.0 Torr. Three kinds of adsorbed thiophene species exist on the alumina surface at saturation coverage:  one in which thiophene interacts with hydroxyl groups, presumably via hydrogen bonding, a second in which thiophene is coordinated via its sulfur atom ...

Wes W. C. Quigley

Papers

Thiophene Hydrodesulfurization over Alumina-Supported Molybdenum Carbide and Nitride Catalysts: Adsorption Sites, Catalytic Activities, and Nature of the Active Surface

Infrared Spectroscopy and Temperature-Programmed Desorption Study of Adsorbed Thiophene on γ-Al2O3

Infrared Spectroscopy and Temperature Programmed Desorption Study of CO on Rh/Al2O3 Catalysts: Probing Overlayer and Support Sites