Promoted Re/Al2O3 systems as sour water-gas shift catalysts

• Published in: Catalysis today 2020-11, Vol.357, p.590-601
• Main Authors: Nikolova, D., Edreva-Kardjieva, R., Kolev, H., Gabrovska, M.
• Format: Article
• Language: English
• Subjects: KCoRe catalyst; Re oxidation states; Sour gas shift catalysts; Sulphur-tolerant water-gas shift reaction; XPS
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2019.05.038

[Display omitted] •Synergistic effect between components is found in most active KCoRe catalyst.•The Re4+/Re7+ ratio gives information about sour WGS activity of rhenium catalysts.•A balance between Re4+ sulphide and Re7+ oxide structures is found in KCoRe catalyst.•The KCoRe system is considered a promising sour WGS catalyst in the 250–400 °C range. Series of Re2O7/γ-Al2O3 catalysts promoted with Ni, Co, and K were studied as sour gas shift catalysts. Samples were prepared by consecutive incipient wetness impregnation. Catalytic measurements were performed in a fixed bed reactor at atmospheric pressure in the range of 180–400 °C at GHSV of 4000 h−1 and steam/gas ratio of 0.3. The samples were characterised by means of N2 physisorption, X-ray diffraction, diffuse reflectance UV–vis spectroscopy, and X-ray photoelectron spectroscopy. It was found that oxidation state ratio of rhenium sulphidic to rhenium oxygen-containing species, namely Re4+/(Re7+(+Re6+)), gives important information about redox relationship between Re4+ and Re7+ oxidation states according to additive type (K, Ni, and Co) and combinations among them. Three factors, namely, uniform deposition of K-Co-Re species on carrier surface, balance between Re sulphidic and oxidic species, and synergism among components were beneficial to the highest activity of KCoRe catalyst. This system was considered a promising catalyst for water-gas shift reaction with sulphur-containing feed in the 250–400 °C temperature range.