Adsorption and reaction of thiophene and H2S on Mo2C/Al2O3 catalyst studied by in situ FT-IR spectroscopy

Abstract

The reactions of both thiophene and H 2 S on Mo 2 C/Al 2 O 3 catalyst have been studied by in situ FT-IR spectroscopy. CO adsorption was used to probe the surface sites of Mo 2 C/Al 2 O 3 catalyst under the interaction and reaction of thiophene and H 2 S. When the fresh Mo 2 C/Al 2 O 3 catalyst is treated with a thiophene/H 2 mixture above 473 K, hydrogenated species exhibiting IR bands in the regions 2800-3000 cm À1 are produced on the surface, indicating that thiophene reacts with the fresh carbide catalyst at relatively low temperatures. IR spectra of adsorbed CO on fresh Mo 2 C/Al 2 O 3 pretreated by thiophene/H 2 at different temperatures clearly reveal the gradual sulfidation of the carbide catalyst at temperatures higher than 473 K, while H 2 S/H 2 can sulfide the Mo 2 C/Al 2 O 3 catalyst surface readily at room temperature (RT). The sulfidation of the carbide surface by the reaction with thiophene or H 2 S maybe the major cause of the deactivation of carbide catalysts in hydrotreating reactions. The surface of the sulfided carbide catalyst can be only partially regenerated by a recarburization using CH 4 /H 2 at 1033 K. When the catalyst is first oxidized and then recarburized, the carbide surface can be completely reproduced.

From Gas to Liquid Phase Sulfidation: An IR Spectroscopy Study

“…However, the m CO fingerprint of Mo 2 C is reported by Aegerter et al [48] and Wu et al[49] at 2054-2060 cm -1 ; and matches the m CO attributed to CO in interaction with CoMoS sites after liquid phase sulfidation. Thus, carbide like species formation after liquid phase sulfidation can not be excluded from our results.…”

Investigation of Organosulfur Adsorption Pathways from Liquid Fuels onto Ag/TiOx–Al2O3 Adsorbents at Ambient Conditions

“…This shift to higher frequencies resulted from the increased electron density within the rings when T molecules were coordinated via the σ interactions between S atoms and surface sites (e.g., cations). , In this case, the adsorbed T rings were oriented perpendicular to the plane of the adsorbent surface. Besides this, the spectrum of the treated TiO x –Al 2 O 3 sample also exhibited a band at 1400 cm –1 , which has been assigned to the δ(CC) s stretching vibrations of T ring adsorbed on surface hydroxyl groups . This further demonstrated the role of surface hydroxyls in sulfur adsorption.…”

“…Besides this, the spectrum of the treated TiO x −Al 2 O 3 sample also exhibited a band at 1400 cm −1 , which has been assigned to the δ(CC) s stretching vibrations of T ring adsorbed on surface hydroxyl groups. 52 This further demonstrated the role of surface hydroxyls in sulfur adsorption. The band was absent in the spectrum of the treated Ag/TiO x −Al 2 O 3 sample, the reason for which might be the incorporation of silver on these sites during the impregnation stage.…”

Hybrid Mo–CT Nanowires as Highly Efficient Catalysts for Direct Dehydrogenation of Isobutane

“…Mo is earth abundant and has a similar electronic structure to Cr. Oxides, carbides, and nitrides of molybdenum have thus been widely utilized in catalytic applications, which but are not limited to alkene isomerization, hydrogenation, hydrogenolysis, and hydrodesulfurization. − In contrast, as a candidate for catalytic dehydrogenation, Mo-based catalyst has been mainly studied in oxidative dehydrogenation of ethane, − propane, − and n -butane in previous studies. , For example, the catalytic performances of molybdenum oxides, including MoO 3 crystallites, MoO x monomers, or polymers, are typically affected by the supporting species, the molybdenum oxidation state, and the dispersion of the metals. Wang and co-workers showed that the Mo/MgAl 2 O 4 catalyst can achieve ca.…”