Characterization of aged hydrotreating catalysts. Part I: Coke depositions, study on the chemical nature and environment

Guichard, Bertrand; Roy-Auberger, Magalie; Devers, Élodie; Rebours, B.; Quoineaud, Anne-Agathe; Digne, Mathieu

doi:10.1016/j.apcata.2009.07.024

Cited by 88 publications

(61 citation statements)

References 34 publications

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“…Five peaks are identified at 1336, 1602, 2700, 2920, and 3200 cm -1 , respectively. The bands at 1336 and 1602 cm -1 are generally considered as the D band and G band [18,19] and attributed to the ring stretching in polyaromatic compounds, which are considered to be the graphite-like carbon species [20,21]. The region of 2700-3000 cm -1 is supposed to be the C-H stretching in alkyl hydrocarbon [19,21,22] while the band at 3200 cm -1 is regarded as the C-H stretching in aromatics [21,22].…”

Section: Ir Characterizationmentioning

confidence: 99%

Coke Formation on Pt–Sn/Al2O3 Catalyst in Propane Dehydrogenation: Coke Characterization and Kinetic Study

et al. 2011

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The influences of gas compositions on the rates of coke formation over a Pt-Sn/Al 2 O 3 catalyst are studied. The coke formed on the catalyst is characterized by thermal gravimetric analysis, IR spectroscopy, Raman spectroscopy and elemental analysis. Two kinds of coke are identified from the TPO profiles and assigned to the coke on the metal and the coke on the support, respectively. The coke formed on the metal is softer (containing more hydrogen) than that formed on the support. The rate of coke formation on the metal is weakly dependent on the propylene and hydrogen pressures but increasing with the propane pressure, while the rate of coke formation on the support is increasing with the propane and propylene pressures and decreasing with the hydrogen pressure. Based on the kinetic analysis, a mechanism for the coke formation on the Pt-Sn/Al 2 O 3 catalyst is proposed, and the dimerization of adsorbed C 3 H 6 is identified to be the kinetic relevant step for coke formation on the metal.

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Section: Ir Characterizationmentioning

confidence: 99%

Coke Formation on Pt–Sn/Al2O3 Catalyst in Propane Dehydrogenation: Coke Characterization and Kinetic Study

et al. 2011

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“…Detailed description of the interpretation of each band identified by Raman can be found elsewhere. [74][75][76] Comparison of the Raman spectra of the slow and fast pyrolysis shows that the second broad peaks (D 3 +D+C-H in slow pyrolysis; D+C-H in fast pyrolysis) decrease significantly when fast heating 35 rates are applied in pyrolysis. The fast catalytic pyrolysis char/coke has the lowest second peak (0.21 in area fraction) among the four.…”

Section: Ftir and Raman Analysis Of Char And Cokementioning

confidence: 99%

Characteristics and origin of char and coke from fast and slow, catalytic and thermal pyrolysis of biomass and relevant model compounds

2013

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Char and coke from biomass catalytic pyrolysis have different origins. They cannot be lumped as one since they occupy different locations on the catalyst surface and, thus, contribute differently to catalyst deactivation. In this study, catalyst (ZSM-5) deactivation in the perspective of comparison of char and coke from pyrolysis of different biomass types is investigated. Pine sawdust, glucose, and cellulose are used as feedstocks in the pyrolysis experiments. Biomass char and coke samples produced via slow and fast, thermal and catalytic pyrolysis are characterized with respect to their overall content, oxidation reactivity, catalyst surface area, pore size distribution changes, bonding groups and their effect on catalyst performance. In particular, it is shown that char forms as an external layer on the catalyst surface and in its macropores, whereas coke forms inside the zeolite micropores via hydrogen transfer and addition reactions. The catalyst effect on glucose and pine slow catalytic pyrolysis is minor compared with that on cellulose slow catalytic pyrolysis, due to macropore blocking by char formation. In fast catalytic pyrolysis, catalyst deactivation is mainly attributed to micropore blocking by coke formation. Char and coke are shown to coexist on the catalyst surface after fast catalytic experiments, with the char content after glucose fast catalytic pyrolysis being 30 wt% of the total solid residue. The origins of char and coke in the cellulose, hemicellulose and lignin components of pine are identified and mechanisms for their formation are proposed.

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“…Between 300 and 450 • C the weight loss (15.9%) corresponded to the elimination of coke associated with S elimination even if m/e = 64 was not detected, probably due to the low signal intensity. It has been proposed [20] that coke eliminated at low temperatures is localized at the surface of MoS 2 particles, the metal favoring coke combustion, while the coke eliminated at higher temperatures could be present at the surface of alumina [21,22]. In order to verify the catalyst composition at different oxidation temperatures, thermal treatments were performed from 250 to 400 °C under air (temperature ramp: 10 °C/min, air flow: 100 mL/min).…”

Section: Characterization Of the Catalyst Before Plasma Treatmentmentioning

confidence: 99%

Elimination of Coke in an Aged Hydrotreating Catalyst via a Non-Thermal Plasma Process: Comparison with a Coked Zeolite

et al. 2019

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The removal of coke from an aged industrial hydrodesulfurization catalyst, using dielectric barrier discharge (DBD) non-thermal plasma with a pin to plate geometry, was investigated. The aged catalyst was introduced into the plasma reactor as a thin wafer. After 130 minutes of plasma treatment, with P = 30 W, 70% of the coke was removed while more than 40% of the sulfur was still present. Characterization of catalyst at different locations of the wafer showed that the coke was more easily removed at the center, close to the pin electrode where the electric field was more intense. The formation of an unexpected phase, under the plasma discharge, was highlighted, it corresponded to the family of Keggin HPA PMo12O40 3−, which could be an interesting precursor of catalyst for the hydrodesulfurization (HDS) process. Compared with a coked zeolite, the rate of regeneration is lower for the HDS catalyst under plasma discharge, while a lower temperature is required under conventional thermal oxidation. This is explained by the presence of metal particles, which could be responsible for the limitation in O-atom formation under plasma.

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Characterization of aged hydrotreating catalysts. Part I: Coke depositions, study on the chemical nature and environment

Cited by 88 publications

References 34 publications

Coke Formation on Pt–Sn/Al2O3 Catalyst in Propane Dehydrogenation: Coke Characterization and Kinetic Study

Coke Formation on Pt–Sn/Al2O3 Catalyst in Propane Dehydrogenation: Coke Characterization and Kinetic Study

Characteristics and origin of char and coke from fast and slow, catalytic and thermal pyrolysis of biomass and relevant model compounds

Elimination of Coke in an Aged Hydrotreating Catalyst via a Non-Thermal Plasma Process: Comparison with a Coked Zeolite

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