Impact of Citric Acid on the Impregnation of CoMoP/γ-Al2O3 Catalysts: Time and Spatially Resolved MRI and Raman Imaging Study

Catita, Leonor; Quoineaud, Anne-Agathe; Moreaud, Maxime; Espinat, D.; Delpoux, O.

doi:10.1007/s11244-018-1038-7

Cited by 8 publications

(3 citation statements)

References 24 publications

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“…Typical hydrotreating catalysts of diesel fraction are CoMo/Al2O3 catalysts with trilobe or quadrilobe granular shape [1][2][3][4][5]. Nowadays, most of the solutions for improving the hydrotreating catalysts are aimed at tuning active component properties, namely, at the selective formation of the active phase [6][7][8][9]. To directly estimate the effect of changes in properties of the active component on catalytic activity, catalytic tests should exclude most of the process interference parameters.…”

Section: Introductionmentioning

confidence: 99%

Testing conditions for CoMo HDS catalyst in the kinetic region: integrated approach using the math calculations and catalytic experiments

Mukhacheva¹,

Vatutina²,

Mik³

et al. 2023

Chim.Tech.Acta

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The main idea of the investigation was to define testing parameters with the lowest influence of internal and external diffusion on catalytic activity in hydrodesulfurization of dibenzothiophene. Traditional experimental methods were used to determine the conditions for the influence of internal and external diffusion. Simultaneous change of a linear feedstock rate and a catalyst loading at constant weight hour space velocity were used to determine the process temperature (240–260 °C) at which the impact of external diffusion is minimal. Catalytic tests, including the variation of the catalyst fraction size, were carried out to define the conditions with the lowest influence of internal diffusion. It was found that when the catalyst with the fraction size of 0.1–0.25 mm was used, the fluctuation of sulfur conversion was the smallest. Besides, to validate experimental results, the calculations were performed with mass balance equations and expressions used for HDS modeling. The resulting data and catalytic experiments demonstrated that the lowest influence of internal and external diffusion is achieved at a temperature process less than 260 °C and a catalyst fraction of 0.1–0.25 mm.

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Section: Introductionmentioning

confidence: 99%

Testing conditions for CoMo HDS catalyst in the kinetic region: integrated approach using the math calculations and catalytic experiments

Mukhacheva¹,

Vatutina²,

Mik³

et al. 2023

Chim.Tech.Acta

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“…The dispersive Raman spectroscopy results obtained from the six selected electrodes are shown in Figure . The largest band between 1408 and 1416 cm –1 is attributed to the citrate with a vibration mode ν s COO – . , The second large band between 1034 and 1047 cm –1 can be ascribed to the δ(P–H) band. , A minor band existing between 314 and 336 cm –1 can probably be ascribed to ν(Ni–P). , The maxima positions of the bands vary depending on the coating condition. The largest shift seems to occur in the ν(Ni–P) band, which can be correlated with the variation in C and O inclusions (Table S1).…”

Section: Resultsmentioning

confidence: 99%

“…The largest band between 1408 and 1416 cm −1 is attributed to the citrate with a vibration mode ν s COO − . 53,54 The second large band between 1034 and 1047 cm −1 can be ascribed to the δ(P−H) band. 55,56 A minor band existing between 314 and 336 cm −1 can probably be ascribed to ν(Ni− P).…”

Section: Electrocoatingmentioning

confidence: 99%

Origin of Electrocatalytic Activity in Amorphous Nickel–Metalloid Electrodeposits

Sarac

Karazehir

Mičušík

et al. 2021

ACS Appl. Mater. Interfaces

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In transition metal-based alloys, the nonlinearity of the current at large cathodic potentials reduces the credibility of the linear Tafel slopes for the evaluation of electrocatalytic hydrogen activity. High-precision nonlinear fitting at low current densities describing the kinetics of electrochemical reactions due to charge transfer can overcome this challenge. To show its effectiveness, we introduce a glassy alloy with a highly asymmetric energy barrier: amorphous NiP electrocoatings (with different C and O inclusions) via changing the applied DC and pulsed current and NaH2PO2 content. The highest hydrogen evolution reaction (HER) activity with the lowest cathodic transfer coefficient α = 0.130 with high J 0 = −1.07 mA cm–2 and the largest surface areas without any porosity are observed for the pulsed current deposition. The calculated α has a direct relation with morphology, composition, chemical state and coating thickness defined by the electrodeposition conditions. Here, a general evaluation criterion with practicality in assessment and high accuracy for electrocatalytic reactions applicable to different metallic alloy systems is presented.

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Speciation of the Oxide Phase of Molybdenum‐Based HDS Catalysts Enhanced with Organic Additives Using an EXAFS/Raman Coupling Methodology

Lesage,

Devers,

Legens

et al. 2024

ChemCatChem

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The ability to gain access to the speciation of hydrodesulfurization catalysts used for removing sulfur from transportation fuels is becoming a key feature in the understanding and improvement of their catalytic activity with the aim of reducing greenhouse gas emissions of fossil fuels. A novel coupling methodology between Raman spectroscopy and X‐ray absorption spectroscopy (XAS) was developed, which allows for precise qualitative and quantitative analysis of the oxide phase of Mo‐based catalysts. This enabled the detailed study of various impregnation parameters and the characterisation of hydrodesulfurization (HDS) catalysts before sulfidation. To illustrate this methodology, the effects of two additives (triethylene glycol and citric acid) were studied. The results demonstrated that organic additives exert a profound influence on the speciation of oxide precursors of molybdenum‐based catalysts. The presence of these additives enhances the dispersion of Keggin or Dawson heteropolyanions on the support by maintaining a high phosphorus‐to‐molybdenum ratio in solution. This is achieved by two strategies: triethylene glycol (TEG) exhibits a pronounced affinity for alumina hydroxyls, while citric acid compensates for phosphate adsorption through the formation of a stable Mo‐citrate complex.

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Impact of Citric Acid on the Impregnation of CoMoP/γ-Al2O3 Catalysts: Time and Spatially Resolved MRI and Raman Imaging Study

Cited by 8 publications

References 24 publications

Testing conditions for CoMo HDS catalyst in the kinetic region: integrated approach using the math calculations and catalytic experiments

Testing conditions for CoMo HDS catalyst in the kinetic region: integrated approach using the math calculations and catalytic experiments

Origin of Electrocatalytic Activity in Amorphous Nickel–Metalloid Electrodeposits

Speciation of the Oxide Phase of Molybdenum‐Based HDS Catalysts Enhanced with Organic Additives Using an EXAFS/Raman Coupling Methodology

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