Infrared Investigation of H₂S Adsorption and Decomposition on Alumina and on Alumina Supported Molybdenum Sulfide

Abstract

Adsorption and subsequent reaction of H2S on alumina gave major i.r. bands at 1341, 1568, 1625, and 3400 cm−1. Relative band intensities were used to follow the first order decomposition of adsorbed H2S and formation of H2O. Rate constants of the surface reaction at 23, 55, and 80 °C were 0.70, 1.48, and 3.42 × 10−3 s−1, respectively. A mechanism consistent with the observed spectral and kinetic data involved adsorption to an exposed Al ion forming an Al—S surface bond, and hydrogen bonding to neighboring O and OH species. It was assumed that the sulfur remained on the surface as a sulfide. The 1568 cm−1 band was discussed in terms of an Al—O species.With adsorption on MoS2–Al2O3, bands appeared at 1330 and 1575 cm−1. Behavior in all respects was similar to that observed on the alumina support alone.

Effect of χ-alumina addition on H 2 S oxidation properties of pure and modified γ-alumina

“…These shift due to interaction with the surface of a heterogeneous catalyst [68][69][70][71][72][73][74][75]. The bands at 13301333 and 25552588 cm -1 are the bending and stretching vibrations of physically adsorbed hydrogen sulfide or chemisorbed HS, respectively [68][69][70][71][73][74][75]. The band at 2588 cm -1 in the spectrum of -Al2O3 treated with H2S indicates that the broad band at 13301368 cm -1 belongs to vibrations of physically ad-sorbed hydrogen sulfide.…”

Hydrogenolysis and hydrogenation of dibenzothiophene catalyzed by sulfided CoO‐MoO3/γ‐Al2O3: The reaction kinetics

“…dissociative adsorption of a molecule such as A, to give two atomically adsorbed species A(s) [\vhere (s) is a single surface site] rcsdts i n a half power on the denominator term K.,C,. Evidence exists for dissociative adsorption of H2S on y-alumina and on MoSZ/y-.41,0:, (Slager and Amberg, 1972;Lunsford et al, 1975). HZS, however, is not a simple diatomic molecule, and we suggest that at least two types of catalytic sites would be involved in its dissociative adsorption.…”

Influence of Process Conditions on the Growth and Texture of CVD Alpha-Alumina

“…In accordance with the model of Slager and Amber [28], the authors suggest the following scenario to take place on the Cl-terminated (0001) surface: The proposed construction nicely describes the recycling of H 2 S on a Cl-terminated α-Al 2 O 3 (0001) surface and explains why very small amounts of H 2 S (usually much less than 0.5 vol % of the total flow), are needed to achieve and maintain the high growth rate.…”

“…According to these studies, H 2 S shifts the rate determining step from the gas phase to the surface. It has also been assumed that H 2 S acts as a true catalyst, dissociating and reforming via adsorption desorption reactions on the surface, these reactions being much faster than H 2 O adsorption explaining the much higher growth rates obtained in the presence of H 2 S. Slager and Amberg [28] suggested steps consisting of H 2 S adsorption on Al +ions forming an Al-S surface bond H-bonding to neighboring O and OH-species followed by its decomposition with water formation. According to this mechanism, both S and O adsorption takes place and the presence of OH-groups is needed.…”