Hydrogenation of naphthalene and methylnaphthalene: modeling and spectroscopy

Abstract

In situ infrared spectra of 1-methylnaphthalene (1-MeNapht) hydrogenation, over sulfided NiMo/Al 2 O 3 -TiO 2 catalysts, were compared with theoretically derived properties of methylnaphthalene and its bicyclic products: MeDilin, MeTetralin, MeOctalin and MeDecalin, and with conversion data from literature. Comparisons were also made between the un-substituted and methyl-substituted two-rings, and between the 1-and 5-methyl isomers of 1,4-dihydronaphthalene (dilin) and 1,2,3,4-tetrahydronaphthalene (tetralin). IR spectra of MeNapht adsorption, on the sulfided catalyst, were matched with data for adsorption on the catalyst without sulfidation and the empty support.Surface bound MeNapht is observed below 250 • C on all catalysts. MeNapht adsorption suppresses OH groups nondiscriminatory on the empty support and the metal loaded catalyst. We relate the results to previous data on the interaction between the supported metal sulfides and titanium modified aluminas.Calculated total energies, and experimentally derived heats of formation, pointed at decahydronaphthalene (decalin) as the dominant product of naphthalene hydrogenation, with tetralin as an abundant intermediate, and dilin and 1,2,3,4,5,6,7,8-octahydronaphthalene (octalin) as short lived transient stages. The spectroscopic modeling showed that the orbital fingerprints of the five bicyclic compounds were not distinctly different, nor more than marginally modified by methyl substitution or isomerization. The only significant difference came at the highest occupied orbital, where a high naphthalene density of states (DoS) overlapped with the valence bands of metal or metal sulfide catalysts.The vibrational bands for naphthalene, dilin, tetralin and octalin were well separated. Octalin and decalin, alone, have similar vibrational spectra. Upheaval of ring degeneracy for methyl-substituted two-ring structures broadened all infrared bands in a characteristic way.

Identification of Refractory Weakly Basic Nitrogen Compounds in a Deeply Hydrotreated Vacuum Gas Oil and Assessment of the Effect of Some Representative Species over the Performance of a Ni–MoS2/Y-Zeolite–Alumina Catalyst in Phenanthrene Hydrocracking

“…On the other hand, by considering the shape of the polynuclear aromatic hetero compounds, those corresponding to DBE 9 and DBE 12, which have planar shapes, may interact better with the surface of the catalyst. In addition, ab initio calculations indicate that the presence of alkyl substituents could induce buckling in some partially hydrogenated species . When these compounds become partially hydrogenated, the planar shape is almost lost because of the configuration of the aliphatic carbons.…”

“…In addition, ab initio calculations indicate that the presence of alkyl substituents could induce buckling in some partially hydrogenated species. 40 When these compounds become partially hydrogenated, the planar shape is almost lost because of the configuration of the aliphatic carbons. That is, with carbons in the sp3 configuration bonded to the aromatic rings, the planarity of the core is lost in such a way that the interaction with the catalyst is hindered for the subsequent removal of the nitrogen heteroatom.…”

Effect of Co and Mo Loading by Impregnation and Ion Exchange Methods on Morphological Properties of Zeolite Y Catalyst

“…Coal tar can be used to produce liquid fuels, such as: gasoline and diesel oil, through the process of hydrocracking [5]. With the aim to enhance the hydrocracking ability of the catalysts, more acid supports, such as: zeolite and TiO2, have been used [6][7][8][9][10][11]. Besides, the conventional cracking function of the acidic sites, the catalytic activities for hydrogenation unsaturated compounds and removal of heteroatoms were also improved with zeolite supports [12][13][14].…”

Electrochemical Hydrogenation of Organic Compounds: A Sustainable Approach

“…The conventional reports for reduction of anthracene includes nickel nanoparticles supported on Attapulgite powder [31] . Further research with carbon supported palladium nanoparticles, [32] nickel supported on Hβ‐zeolite catalyst, with the help of supercritical carbon dioxide solvent, [33] frustrated Lewis pair (B(C 6 F 5 ) 3 /Ph 2 PC 6 F 5 ) assisted hydrogenation, [30] and many more conventional methods have been reported [31–35,233] …”