The chemistry of the hydrodesulphurization process (Review)

Zdražil, Miroslav

doi:10.1016/0166-9834(82)80242-x

Cited by 56 publications

(20 citation statements)

References 68 publications

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“…Considering that sulfur adsorption was improbable, Singhal (9) has proposed a mechanism involving a preliminary hydrogenation of the molecule thus occuring after a π-adsorption, leading to a dihydrodibenzothiophene, a common species to the both routes of transformation usually observed. A study by Zdrazil about the transformation of thiophene, benzothiophene, and dibenzothiophene supports this hypothesis of such hydrogenated intermediates (10).…”

Section: Introductionmentioning

confidence: 85%

See 1 more Smart Citation

Hydrodesulfurization of Alkyldibenzothiophenes over a NiMo/Al2O3Catalyst: Kinetics and Mechanism

Meille

Schulz

Lemaire

et al. 1997

Journal of Catalysis

192

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Section: Introductionmentioning

confidence: 85%

“…with [10] representing the adsorption equilibrium constant of compound i at the surface. It has been checked (14) that under our experimental conditions, a pressure of 5 MPa still corresponds to the range of low hydrogen pressure and thus that the above expression can be used.…”

Section: At the Stationary State Ofmentioning

confidence: 99%

Hydrodesulfurization of Alkyldibenzothiophenes over a NiMo/Al2O3Catalyst: Kinetics and Mechanism

Meille

Schulz

Lemaire

et al. 1997

Journal of Catalysis

192

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“…Over time, Zdrazil [3] also acknowledged that only a partial saturation of the ring seems necessary in the first step. Sullivan and Ekerdt [9] observed the formation of dihydrothiophenes (DHTs) and THT, and proposed the partial thiophene hydrogenation to 2,5-DHT with subsequent S-elimination as the major path for thiophene HDS.…”

mentioning

confidence: 96%

“…In spite of various reviews on this topic, only some [1][2][3][4][5][6] are cited here, the key details remain debatable; no agreement was reached even on the initial step of thiophene HDS. There are several proposals for the thiophene HDS pathway.…”

mentioning

confidence: 99%

Deuterium Tracer Experiments Prove the Thiophenic Hydrogen Involvement During the Initial Step of Thiophene Hydrodesulfurization

Katsapov

Braun

2010

Catal Lett

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We reassess literature data and demonstrate that the intermolecular hydrogen transfer occur likely during the primary catalytic interaction between thiophene molecules, rendering it the credible thiophene hydrodesulfurization (HDS) pathway. Deuterium tracer experiments prove that thiophenic hydrogen plays a part in direct C-S cleavage, in the initial step of thiophene HDS. Hypothetical surface intermediates for thiophene exchange do not precede, i.e. do not form prior to the surface intermediates for thiophene HDS. Therefore the established thiophene exchange/HDS scheme and the sequence of events are not the viable concepts. Since the deuterium data also indicate that C 4 H 5 S(a)-radicals are not formed this means there are no common surface or reaction intermediates for the thiophene exchange and HDS and both reactions proceed parallel.Keywords Thiophene hydrodesulfurization mechanism Á Deuterium tracer experiments Á Intermolecular hydrogen transfer Á HD exchangeThe mechanism of thiophene hydrodesulfurization (HDS) requires further discussion. The authors' interpretation of the previous works that used deuterium as a tracer is mostly inconsistent with their experimental results. At least six essential facts in these works must be discussed. The first work contains two crucial facts, which escaped the attention of the authors and also went unnoticed by the readers. These and other results invalidate the major proposal of their subsequent works, i.e. that dihydrothiophenes are possible reaction intermediates for thiophene HDS. In reality, exactly past works with the use of deuterium already contain several important deuterium tracer facts, which testified that the thiophenic hydrogen could play a part in direct C-S cleavage, in the initial step of thiophene hydrodesulfurization. Our aim is to illustrate that the intermolecular hydrogen transfer may likely occur during the primary catalytic interaction between thiophene molecules and that such mechanism of thiophene transformation can be considered as the credible thiophene HDS pathway.While thiophene hydrodesulfurization (HDS) has been extensively studied, the main contribution to understanding of potential HDS pathways was made by product distribution and kinetic studies as well as by deuterium tracer experiments. In spite of various reviews on this topic, only some [1-6] are cited here, the key details remain debatable; no agreement was reached even on the initial step of thiophene HDS. There are several proposals for the thiophene HDS pathway. Amberg [2] concluded after product distribution studies that thiophene undergoes hydrogenolysis without prior ring hydrogenation, and that it is followed by a sequence of olefin hydrogenations; i.e. the initial step of thiophene (Th) HDS is the C-S cleavage.Th þ H 2 ! H 2 S þ 1:3 butadiene; butenes which can further hydrogenateKraus and Zdrazil [7] observed the formation of tetrahydrothiophene (THT) during the thiophene HDS and interpreted this as evidence for a consecutive Electronic supplementary material The online ve...

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“…Those heterocyclic molecules are often met among the crude oil residues which are submitted to hydrotreating in oil industries (Proskouryakov et al, 1983;Zdrazil, 1982;Mensah, 1987). During an industrial process of hydrotreating of crude oil, heteroatoms such as S, O and N, are eliminated from heterocyclic molecules.…”

Section: -Methyltetrahydrothiophenementioning

confidence: 99%

Comparative study of hydrogenolysis of a C-X bond in three homologous heterocyclic compounds of chemical formula C5H10X with X = S, O and NH

Atohoun¹,

Kuevi²

2012

AJSIR

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A theoretical study of hydrogenolysis of a C-X bond of 2-methyltetrahydrothiophene (2-MTHT), 2-methyltetrahydrofuran (2-MTHF) and 2-methylpyrrolidine (2-MP) molecules, over molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ) has been performed by MP2 calculations in the Lanl2DZ basis set. Both catalysts were modeled by catalytic sites with three anionic vacancies MoS 3 H 3 + and WS 3 H 3 + respectively. The temperature and pressure conditions respected in the study are respectively 573 K and 70 atm. The obtained results shown that, the Hydrogenolysis of a C-X bond of methyled carbon of 2-MTHT and 2-MTHF molecules led to the formation of 1-pentanethiol and 1-pentanol adsorbed over the each catalyst. On the other hand, in the case of the 2-MP molecule, the catalytic site was implicated in the reaction with formation of hydrogen sulfide (H 2 S). The Hydrogenolysis activation energies of various transformations were variable from MoS 2 to WS 2 catalysts except for 2-MTHT. In presence of a same kind of catalyst, the activation energies of Hydrogenolysis of the C-X bond (methyled carbon atom) of 2-MTHF and 2-MTHT increase in the order X = O, S.

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The chemistry of the hydrodesulphurization process (Review)

Cited by 56 publications

References 68 publications

Hydrodesulfurization of Alkyldibenzothiophenes over a NiMo/Al2O3Catalyst: Kinetics and Mechanism

Hydrodesulfurization of Alkyldibenzothiophenes over a NiMo/Al2O3Catalyst: Kinetics and Mechanism

Deuterium Tracer Experiments Prove the Thiophenic Hydrogen Involvement During the Initial Step of Thiophene Hydrodesulfurization

Comparative study of hydrogenolysis of a C-X bond in three homologous heterocyclic compounds of chemical formula C5H10X with X = S, O and NH

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