Catalytic Hydrogenation of Multiring Aromatic Coal Tar Constituents

Wiser, W.H.; Singh, Surjit; Qader, S.A.; Hill, George R.

doi:10.1021/i360035a017

Cited by 35 publications

(13 citation statements)

References 5 publications

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“…The first one is the direct cracking of the central ring to monocyclic aromatics, and the second one is the isomerization and hydrogenation of the terminal ring with next cracking to bicyclic or monocyclic aromatic hydrocarbons. Wiser et al − showed that 9,10-DHA prefers the hydrogenation and cleavage of the terminal ring rather than the cleavage of the central ring under catalytic and thermal hydrocracking conditions. Cowley et al investigated anthracene hydrocracking to benzene and its alkyl derivatives to determine the thermodynamic possibility of converting multicyclic aromatics into monocyclic aromatics via the selective hydrocracking of the central ring.…”

Section: Introductionmentioning

confidence: 99%

Hydrocracking of Fused Aromatic Hydrocarbons Catalyzed by Al-Substituted HZSM-5—A Case Study of 9,10-Dihydroanthracene

zhang

et al. 2020

ACS Catal.

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To investigate the hydrocracking mechanisms of polycyclic aromatic hydrocarbons, we used HZSM-5 with one Al substitution (T1, T3, T5, T7, T11, and T12) as a solid acid catalyst and 9,10-dihydroanthracene as a model substrate on the basis of periodic density functional theory computations. It is found that the intersection of the straight and sinusoidal channels is energetically more favored than the individual sinusoidal and straight channels due to their different local environments. On the basis of the computed Gibbs free energy at 500 °C, the rate-determining step for the formation of 1-benzyl-2-methylbenzene as the first intermediate is the heterolytic activation of H 2 , which is encapsulated in a conjugated frustrated Lewis pair (FLP), generated from the acidic O−H proton transfer to the hydrocarbon substrate. For the subsequent formation of toluene or benzene and o-xylene from 1-benzyl-2-methylbenzene hydrocracking, the rate-determining step, which is the heterolytic activation of H 2 encapsulated in a conjugated FLP, determines the selectivity. On the basis of the apparent Gibbs free energy barriers at 500 °C, the activity has the decreasing order of T5 > T11 > T1 ≈ T12 ≈ T3 ≈ T7. It is noted that there is no correlation between the Gibbs free energy barriers and the acidic strength based on O−H deprotonation Gibbs free energy and the adsorption enthalpy of pyridine as a probe molecule.

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Section: Introductionmentioning

confidence: 99%

Hydrocracking of Fused Aromatic Hydrocarbons Catalyzed by Al-Substituted HZSM-5—A Case Study of 9,10-Dihydroanthracene

zhang

et al. 2020

ACS Catal.

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“…The catalysts reported to date for the hydrogenation of anthracene are diverse. Monometallic silica‐supported Pt, hydroprocessing presulfided CoMo/Al 2 O 3 , and NiMo/Al 2 O 3 and NiW/Al 2 O 3 are among the most utilized, the selectivities of which are controlled by the factors discussed above. NiMo/Al 2 O 3 and NiW/Al 2 O 3 have the advantage of bifunctionality, in which the metal function promotes hydrogenation and the acidic function promotes isomerization, ring opening, and dealkylation.…”

Section: Introductionmentioning

confidence: 99%

Hydrogenation of Condensed Aromatic Compounds over Mesoporous Bifunctional Catalysts Following a Diels–Alder Adduct Pathway

et al. 2016

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Pt(0.5 wt %)‐Al‐SBA‐15 and Pt(0.5 wt %)‐Al‐MCM‐41 bifunctional catalysts were prepared by wet impregnation and investigated in the hydrogenation of anthracene and the hydrogenolysis/hydrogenation of a series of synthesized Diels–Alder adducts with anthracene and anthracene derivatives. The mesoporous texture of the investigated catalysts allowed the hydrogenation of these substrates to a large extent. In direct correlation with the size of the Pt particles, Pt‐Al‐SBA‐15 exhibited a higher activity. Both catalysts exhibited a strong Lewis acidity associated with the presence of the Al extra‐framework species. The acidity of these catalysts afforded the esterification of the reaction byproduct, that is, succinic anhydride, with methanol or ethanol, and the hydrocracking/decyclization of one hydrogenated ring to lead to 1,2,3,4‐tetrahydronaphthalene derivatives. A good correlation with the calculated values of the reaction Gibbs free energy has been evidenced.

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“…Beyond that, some hydrocarbon cracking must have occurred. Our compositional data are not of sufficient detail to determine the relative importance of ring-opening cracking reactions to the breaking of alkyl linkages between rings in contributing to the higher yields of low-ring-number compounds although the literature suggests hydrocarbon ring-opening reactions with similar catalysts at these temperatures are not very significant (20,21,22), amounting to less than 10 percent for phenanthrene in a flow reactor (21) and less than 5 percent for anthracene after 200 minutes at 390° C in a batch autoclave reactor (20).…”

Section: Ring Number Distributions Examination Of the Data Inmentioning

confidence: 86%

“…Some scatter in compositional data could be expected because of the variation in individual preparations. However, since conditions generally were such as to avoid significant cracking of hydrocarbons, especially hydrocarbon ring structures (20,21,22), differences or similarities in basic hydrocarbon structures should be valid. One of the largest uncertainties is the extent of hydrogenation of aromatic hydrocarbon rings originally present in the coal.…”

Section: Composition Of Coal Liquidsmentioning

confidence: 99%