Catalytic performance stability of Mo, W and Re-based sour water–gas shift catalysts

Catalytic Ability of K- and Co-Promoted Oxo-Re and Oxo-ReMo Nanosized Compositions for Water–Gas Shift Reaction

“…Along with this, the existence of K-Re-O species on the surface, where the Re 7+ (Td) state is also dominant, could not be excluded. The increase in the absorption intensity above 270 nm points to an interaction between potassium and other components and the appearance of new K-Co-Re-O-(Al) species on the surface, which could not be identified by PXRD [16,17].…”

“…A completely formed spinel structure containing only Co 2+ ions (Co 2+ Al 3+ 2O was formed at high temperatures of about 1000 °C. It is also known that Co 2+ io were incorporated into the lattice of γ-Al2O3, and a spinel structure was formed cobalt concentrations within 2 wt.% of CoO [24] (and references herein); -A deposited CoO amount of 3 wt.% generated another spinel structure, Co3 (CoO.Co2O3), in which Co 2+ and Co 3+ ions occupy octahedral (Oh) positions; -Based on previous studies of this system [16,17], an interaction between Co and to form weakly bonded Co-Re-O-(Al) surface species is also possible.…”

“…CoReMo: The introduction of molybdenum into the CoRe system caused substantial transformations, not only a color transformation to gray-beige (Table 1 and Figure species are also possible [16,25]. The introduction of Mo species increased the absorption of the catalyst in the region above 250 nm, denoting that part of the Mo species was in the form of polymeric Mo species in octahedral symmetry.…”

“…In an attempt to study and find an alternative to rhenium, which is one of the rarest elements in the Earth's crust, one initial approach would be to replace half of the rhenium content with molybdenum, which is more affordable. The introduction of Mo as a component in this system was justified by the activity of sour Mo-based catalysts, such as K-CoMo and K-NiMo, in our own previous investigations [16]. The current fundamental study includes an assessment of the catalytic capability of the oxo-(K)CoRe and (K)CoReMo catalysts after activation via a reduction treatment under the influence of a redox environment of reducing CO and oxidizing H 2 O steam reagents.…”

“…A couple of years ago, our studies were focused on a sulfided Re/Al 2 O 3 system promoted by K, Co, and Ni as sour WGS catalysts [16,17]. A KCoRe version was considered a promising catalyst for the WGS reaction with sour gases, i.e., H 2 S-containing process stream, at medium reaction temperatures in the 250-400 • C range and a CO conversion over 90%.…”