The effect of metal type on the sulfur tolerance of catalysts supported on niobia for sour water-gas shift reaction

Silva, Ludmila P.C.; Freitas, Marina M.; Santos, Rachel Moreira Morais dos; Pérez, Gerónimo; Terra, Luís E.; Coutinho, Ana C.S.L.S.; Passos, Fábio B.

doi:10.1016/j.ijhydene.2017.12.144

Cited by 16 publications

(7 citation statements)

References 45 publications

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“…Pt/Nb 2 O 5 exhibited an intermediate activity during the clean WGS test (with Au giving the best activity results) but while in the case of the Au sample the activity dropped to zero in the presence of H 2 S, the Pt catalysts presented no deactivation for the whole 4 h test. Because of the high sulphur resistance, the catalyst was tested also with an H 2 S concentration of 1000 ppm and the activity still remained unvaried; with the introduction of a clean stream after the sulphur resistance test was, instead, observed an increase in the activity that did not decrease for the following 20 h. While the recovery of the initial activity could be explained by the low stability of the S-Pt bond, the enhancement in the catalytic performance after sulphur exposure remains not clarified: a possible reason could be the formation of niobium sulphide in the catalyst surface, which could act as new active sites [198]. As discussed in the first part of this paragraph, sulphur exposure is not the only driving factor for a WGS catalyst deactivation.…”

Section: Deactivation Studiesmentioning

confidence: 93%

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Palma

Ruocco

Cortese

et al. 2020

Metals

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The water gas shift (WGS) is an equilibrium exothermic reaction, whose corresponding industrial process is normally carried out in two adiabatic stages, to overcome the thermodynamic and kinetic limitations. The high temperature stage makes use of iron/chromium-based catalysts, while the low temperature stage employs copper/zinc-based catalysts. Nevertheless, both these systems have several problems, mainly dealing with safety issues and process efficiency. Accordingly, in the last decade abundant researches have been focused on the study of alternative catalytic systems. The best performances have been obtained with noble metal-based catalysts, among which, platinum-based formulations showed a good compromise between performance and ease of preparation. These catalytic systems are extremely attractive, as they have numerous advantages, including the feasibility of intermediate temperature (250–400 °C) applications, the absence of pyrophoricity, and the high activity even at low loadings. The particle size plays a crucial role in determining their catalytic activity, enhancing the performance of the nanometric catalytic systems: the best activity and stability was reported for particle sizes < 1.7 nm. Moreover the optimal Pt loading seems to be located near 1 wt%, as well as the optimal Pt coverage was identified in 0.25 ML. Kinetics and mechanisms studies highlighted the low energy activation of Pt/Mo2C-based catalytic systems (Ea of 38 kJ·mol−1), the associative mechanism is the most encountered on the investigated studies. This review focuses on a selection of recent published articles, related to the preparation and use of unstructured platinum-based catalysts in water gas shift reaction, and is organized in five main sections: comparative studies, kinetics, reaction mechanisms, sour WGS and electrochemical promotion. Each section is divided in paragraphs, at the end of the section a summary and a summary table are provided.

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Section: Deactivation Studiesmentioning

confidence: 93%

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Palma

Ruocco

Cortese

et al. 2020

Metals

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“…Seeing H 2 S as the simplest "thiol" makes it a good model adsorbate to explore the formation of alkanethiol monolayers (MLs) on gold by self-assembly. 1−3 Both on thermodynamical and kinetic grounds, the considerable ease with which the interaction of H 2 S with its surfaces generates stable metal sulfides 4−6 enables these systems to attract much attention in various fields of science, in particular, the catalyst poisoning by sulfur compounds, 7,8 hydrodesulfurization of hydrocarbon, 9,10 and gas sensors. 11,12 Such a fast kinetics imposes a difficulty in finding out the detailed process of H 2 S decomposition even at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Microkinetics of H₂S Interactions with Clean and Sulfided Au(110) at Low Temperature: A Strong Assistance in Partial Dissociation from Single Sulfur Atoms

et al. 2022

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A microkinetic model built on first-principles calculations is developed to clarify an ongoing experimental controversy regarding whether hydrogen sulfide (H 2 S) molecules are intact or dissociated on pristine and S-covered Au(110) surfaces at 120 K. From the simulation, we prove that only associative adsorption of H 2 S on the defect-free, flat (110) facet of gold occurs in the exposure region under investigation, whereas its reaction with sulfur adsorbed as single atoms straightforwardly proceeds to yield relatively strongly bound SH radicals for the surface precovered with elemental S. The sulfur assistance of neighboring H 2 S to decompose is ascribed to the stability of the corresponding transition state in which three-center hydrogen bonding interactions are being formed. One-dimensional zigzag chains of divalent sulfur are shown as structural units of the c(2 × 4) superstructure observed experimentally in inactive sulfur islands for the S + H 2 S reaction. The sensitivity of H−S bond cleavage in surface H 2 S to the aggregation state of coadsorbed sulfur may, in part, be rationalized by the change in valency of these adatoms. This is the first time that a clear theoretical picture of the chemistry of H 2 S on such an open Au surface is provided, which is beneficial to elucidate more complicated reaction processes, such as sulfurpoisoning tolerance of gold nanocatalysts.

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“…For heterogeneous catalysis, numerous works are found in the literature on the application of metallic oxides [34][35][36][37][38]. The compounds that contain niobium have been investigated among researchers in their search for heterogeneous catalysts with better performance in several areas of application [39][40][41][42][43]. Cruz et al [44] evaluated the catalytic activity of niobium phosphate (NBP) in the benzylation of methoxybenzene with styrene, benzyl alcohol, and benzyl chloride.…”

Section: Introductionmentioning

confidence: 99%

“…For heterogeneous catalysis, numerous works are found in the literature on the application of metallic oxides . The compounds that contain niobium have been investigated among researchers in their search for heterogeneous catalysts with better performance in several areas of application . Cruz et al.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Soybean Oil Hydrolysis on Niobium Catalysts

et al. 2020

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The catalytic hydrolysis of soybean oil was used as an alternative for the production of monoglycerides (MG) and diglycerides (DG). The reactions were conducted in a stainless-steel tubular reactor in the temperature range of 240-290°C, on niobium phosphate (NBP) and niobium oxide (NBO) as catalysts. In the hydrolysis reactions at 270°C, the maximum selectivities of the products of interest were obtained at 22 % MG and 48 % DG for the reaction with NBP, and 7 % MG and 33 % DG with NBO, for 59 % and 36 % of triglyceride conversion in 10 min, respectively. The proposed kinetic model presented a good fit of the theoretical model with the experimental data, showing that the previous hypotheses considered for the mechanism development are suitable for describing the kinetics of soybean oil hydrolysis.

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The effect of metal type on the sulfur tolerance of catalysts supported on niobia for sour water-gas shift reaction

Cited by 16 publications

References 45 publications

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Ab Initio Microkinetics of H₂S Interactions with Clean and Sulfided Au(110) at Low Temperature: A Strong Assistance in Partial Dissociation from Single Sulfur Atoms

Kinetics of Soybean Oil Hydrolysis on Niobium Catalysts

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The effect of metal type on the sulfur tolerance of catalysts supported on niobia for sour water-gas shift reaction

Cited by 16 publications

References 45 publications

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Platinum Based Catalysts in the Water Gas Shift Reaction: Recent Advances

Ab Initio Microkinetics of H2S Interactions with Clean and Sulfided Au(110) at Low Temperature: A Strong Assistance in Partial Dissociation from Single Sulfur Atoms

Kinetics of Soybean Oil Hydrolysis on Niobium Catalysts

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Ab Initio Microkinetics of H₂S Interactions with Clean and Sulfided Au(110) at Low Temperature: A Strong Assistance in Partial Dissociation from Single Sulfur Atoms