Hydrogenation Of Naphthalene Research Articles

Hydrogenation of Naphthalene on HY/MCM-41 Composite Supported Sulfided Ni-Mo Catalysts

A series of mesoporous molecular sieves, MCM-41 with different Si/Al molar ratios, were synthesized by hydrothermal method. The influence of aluminum content on the properties and pore structure of MCM-41 molecular sieves was investigated. The supported Ni-Mo catalysts with MCM-41 and γ-Al2O3 as supports were synthesized by impregnating with Ni-Mo-P solution. The activity of the catalysts was characterized by hydrogenation of naphthalene. The influence of Si/Al ratio of MCM-41 on hydrogenation activity of the catalysts was investigated. The results indicated that the relative crystallinity of MCM-41 decreases with the increase of aluminum content in the molecular sieves; however, the hydrogenation activity of the catalysts, especially the ring-opening activity, increases with the increase of aluminum content. The synergistic effect for hydrogenation of naphthalene was found by mixing MCM-41 and HY molecular sieves. At 360°C the catalysts with HY and MCM-41 mixture as supports had higher activity. The reaction network for hydrogenation of naphthalene includes two parallel pathways; naphthalene was hydrogenated to tetralin, then the isomerization and ring-opening of tetralin occurred, or tetralin was further hydrogenated to decalin, followed by the isomerization and ring-opening of decalin.

Nanosized Pd/Pt and Pd/Rh Catalysts for Naphthalene Hydrogenation and Hydrogenolysis/Ring-opening

Pd/Rh and Pd/Pt catalysts supported on two different mesoporous materials – a Zr-doped MCM-41-type silica [Si/Zr = 5 w/w (SiZr)] and a commercial silica-alumina [Si/Al = 40:60 w/w (SiAl)] – were prepared by incipient wetness impregnation using nanosized suspensions of alloy particles prepared by polyol-mediated synthesis in diethylene glycol (DEG). The catalytic behaviour of these catalysts was investigated in the hydrogenation and hydrogenolysis/ring-opening of naphthalene at 6.0 MPa, by checking the role of both the main reaction conditions (temperature, contact time and H2/naphthalene molar ratio) and increasing amounts of dibenzothiophene (DBT). The catalysts supported on SiAl showed higher activity than catalysts supported on SiZr, thus suggesting that activity is favoured by higher acidity of the support and/or higher interaction of the nanosized metal particles with the support. While using the SiZr support, weaker metal-support interactions took place by forming catalysts with bigger metal and/or metal oxide particles. Besides, the catalyst with lowest noble-metal content (0.3 wt.%) (SiAl-0.3Pd/Pt-5) had the greatest acidity and metal surface and, consequently, the highest activity. Furthermore, it exhibited a good thiotolerance in presence of increasing amounts of DBT in the feed, thus maintaining a high catalytic activity in the hydrogenation of naphthalene, although with decreased yield in trans- and cis-decalin (decahydronaphthalene or DeHN) and high-molecular-weight compounds (H.M.W.), with a corresponding increased yield in the partially hydrogenated tetralin (tetrahydronaphthalene or TeHN).

Enhancement of naphthalene hydrogenation over PtPd/SiO 2–Al 2O 3 catalyst modified by gold

This contribution describes the effect of support (amorphous silica–alumina: ASA and multi-wall carbon nanotubes: MWNT) on the catalytic response of bimetallic PtPd catalysts in naphthalene hydrogenation (HYD). In addition, the effect of Au incorporation on the activity of PtPd/ASA catalyst was studied. The ternary AuPtPd/ASA catalyst was prepared by the simultaneous reduction of metal precursors by ethanol in the presence of poly( N-vinyl-2-pyrrolidone) (PVP), whereas binary PtPd/ASA and PtPd/MWNT catalysts were prepared by a conventional impregnation method. The catalysts were characterized using chemical analysis, nitrogen adsorption–desorption isotherms at 77 K, CO chemisorption, FTIR spectra of chemisorbed CO, transmission electron microscopy (TEM), DRIFT of adsorbed NH 3, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) measurements. Under the reaction conditions employed ( T = 448–463–483 K, P = 2.0 MPa, WHSV = 45.7 h −1), the ternary AuPtPd/ASA catalyst showed highest naphthalene conversion and lowest deactivation among the catalysts studied. The S-tolerance of this catalyst was confirmed during simultaneous naphthalene and toluene HYD in the presence of dibenzothiophene (DBT; 100 ppm of S). The enhanced activity and S-tolerance observed with the AuPtPd/ASA catalyst was related to its larger metal surface exposure, as determined by XPS, and the “ensemble” effect of the Au 70Pd 30 and Au 42Pd 58 alloy particles formed on ASA, as demonstrated by XRD. It is proposed that surface gold weakens the adsorption of aromatic compounds (toluene/naphthalene/DBT), facilitating product desorption. Contrary to acidic AuPtPd/ASA, the less acidic PtPd/MWNT catalyst did not show S-resistance in reaction of benzene HYD in the presence of 1-butanethiol. The contribution of the acid sites of support to catalyst S-resistance and their deactivation by coke are discussed.

Ring hydrogenation of naphthalene and 1-naphthol over supported metal catalysts in supercritical carbon dioxide solvent

Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst.

Catalytic Activity of Exfoliated MoS2 in Hydrodesulfurization, Hydrodenitrogenation and Hydrogenation Reactions

The activity of exfoliated MoS2 in the hydrodesulfurization (HDS) of dibenzothiophene, the hydrodenitrogenation (HDN) of carbazole and the hydrogenation of naphthalene has been determined. The catalytic activity was compared to MoS2 prepared by the decomposition of molybdenum naphthenate (MoNaph). Exfoliated MoS2 was found to give better overall HDS activity compared to MoNaph derived MoS2 catalyst, whereas MoNaph derived MoS2 was found to give higher hydrogenation and HDN activity. These results are discussed in terms of the morphology of the two catalysts. The relative activity of the two catalysts in the hydrotreating reactions is shown to be different to that obtained during Cold Lake bitumen hydrocracking.

Role of Pt in high performance Pt-Mo catalysts for hydrotreatment reactions

The effect of Pt/(Pt + Mo) atomic ratio, metal content and the characteristics of the alumina support on activity and synergy in hydrotreatment (HDT) reactions were studied. Pt-Mo supported on different commercial gamma alumina (γ-Al 2O 3) catalysts with different metal contents were prepared and evaluated in simultaneous dibenzothiophene (DBT) hydrodesulfurization (HDS) and naphthalene hydrogenation (HYD) reactions. The characterization of the catalysts was performed using CO chemisorption, proton affinity distribution (PAD) and infrared (IR) spectroscopy of adsorbed NO. The Pt/(Pt + Mo) atomic ratio drastically influences the catalytic behavior. The formation of active sites with high activity and an important synergistic effect is enhanced at a very specific low metals composition of the catalysts. The characterization results suggest that the enhanced HDS and HYD activities are due to an improved dispersion of the active species on the support, which was reached at low metal contents and a specific atomic ratio. Moreover, this improved dispersion was influenced by the surface composition of the alumina and could be associated with a specific interaction between the Pt and the hydroxyl groups of the alumina as well as with the formation and distribution of the Mo active phase exposed on the support.

Tuning cis-decalin Selectivity in Naphthalene Hydrogenation Over Carbon-supported Rhodium Catalyst Under Supercritical Carbon dioxide

Catalytic hydrogenation of naphthalene to decalin was studied over a carbon-supported rhodium catalyst in supercritical carbon dioxide solvent at 333 K, and the results were compared with those in an organic solvent. cis-, trans-Decalin and tetralin were formed from the beginning of the reaction in supercritical carbon dioxide. Higher concentration of hydrogen in carbon dioxide solvent and on the active site, and also the suppression of desorption of partially hydrogenated tetralin molecules from the active site would be responsible for higher selectivity to cis-decalin in supercritical carbon dioxide than that in an organic solvent.

ケミカルハイドライド法水素貯蔵における低品位水素の利用（6）CO存在下でのナフタレン水素化反応における担持Ni触媒の活性

ケミカルハイドライド法水素貯蔵における低品位水素の利用（6）CO存在下でのナフタレン水素化反応における担持Ni触媒の活性

On the origin of the high performance of MWNT-supported PtPd catalysts for the hydrogenation of aromatics

This work reports some surface and structural features of multi-wall carbon nanotubes (MWNT)-supported PtPd crystallites in order to explain their very good ability to hydrogenate aromatic rings in comparison with other catalyst systems consisting of the same metallic function but changing the support substrate (amorphous SiO 2–Al 2O 3 (ASA) and silica-delaminated zirconium phosphate (ZrPSi)). The bimetallic PtPd catalysts were prepared by simultaneous impregnation of the respective supports with metal salt precursors and characterized using chemical analysis, nitrogen adsorption–desorption isotherms at 77 K, temperature-programmed desorption-mass spectroscopy (TPD-MS), DRIFT of adsorbed NH 3 (DRIFT-NH 3), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy measurements (XPS). The catalysts were tested in the vapor-phase simultaneous hydrogenation (HYD) of naphthalene and toluene in the presence of dibenzothiophene (DBT; 100 ppm of S) at 5 MPa of total pressure. Irrespectively of the reactant molecule, the PtPd/MWNT catalyst showed a higher initial turnover frequency (TOF) than the PtPd/ZrPSi and PtPd/ASA counterparts. The enhancement of activity observed with the PtPd/MWNT catalyst was related to the ensemble effect of Pt 48Pd 25 alloy located on the outer surface of the MWNT. Upon on-stream conditions the PtPd/MWNT showed the lowest thioresistence, sintering and coking among the catalysts studied. The improved resistance of this catalyst to metal sintering and coking is interpreted in terms of the reactivity changes of the coke precursors induced by adsorbed sulfur as well as the lowest acidity of this catalyst.

Characterization and catalytic activity of Ni/SBA-15, synthesized by deposition–precipitation

SBA-15 was synthesized and used as support for a Ni catalyst prepared by deposition–precipitation (D–P). Support and catalyst were characterized by nitrogen physisorption, XRD, HREM and temperature programmed reduction (TPR). The results show that, at the Ni loading used here (10.3 wt% Ni), SBA-15 preserves its hexagonal porous arrangement. After the D–P process, the Ni phases deposited on SBA-15 were 1:1 nickel phyllosilicate and nickel hydroxide. Transmission electron microscopy (TEM) observations and the evaluation of the reduced catalyst in the hydrogenation of naphthalene showed that with the D–P synthesis method it is possible to obtain Ni/SBA-15 catalysts with high dispersion and metal loading. The catalyst obtained by D–P showed higher activity in the hydrogenation of naphthalene than one prepared similarly but using MCM-41 as support.

Efficient hydrogen supply from tetralin with superheated liquid-film-type catalysis for operating fuel cells

A catalytic reaction pair, consisting of tetralin dehydrogenation/naphthalene hydrogenation, has newly been proposed as a storage medium of hydrogen for operating polymer-electrolyte fuel cells. The hydrogen storage capacity of tetralin (3.0 wt.%, 28.2 kg-H 2/m 3) is lower than that of decalin (7.3 wt.%, 64.8 kg-H 2/m 3), with the decalin dehydrogenation/naphthalene hydrogenation pair operated. Nevertheless, the rates of tetralin dehydrogenation and naphthalene hydrogenation to tetralin are much faster than the rates of the latter reaction pair. With respect to hydrogen storage for static or domestic use with space advantages, tetralin would be superior to decalin due to the ability of supplying hydrogen easily. Very high reaction rates and conversions of hydrogen evolution from tetralin were accomplished stationarily with “superheated liquid-film-type catalysis” by heating at 210–240 °C, in contrast to the poor results obtained with ordinary suspended catalysis. In particular, a carbon-supported nano-size platinum catalyst in the superheated liquid-film state exhibited efficient tetralin conversion as high as 95% within 25 min contact at 240 °C under distillation conditions. At the same temperature range, the dehydrogenation rates for decalin that had been obtained were ca. 3.9–6.3 times slower than those for tetralin, suggesting the excellent characteristics of tetralin as a hydrogen storage medium. In addition, carbon-supported nickel–ruthenium composite catalysts were found to give dehydrogenation activities at 240 °C comparable with those of the platinum catalyst at 210 °C.

A novel Ni2Mo3N/MCM41 catalyst for the hydrogenation of aromatics

Bulk and MCM41-supported Ni2Mo3N catalysts were prepared using a temperature-programmed reduction (TPR) method and characterized using XRD, TEM, ICP-AES, and N2 adsorption analysis techniques. Their catalytic properties were measured for the simultaneous hydrogenation of p-xylene and naphthalene and compared with Ni/MCM41 and Mo2N/MCM41 catalysts having similar metal loadings. The results indicate that the Ni2Mo3N/MCM41 catalyst exhibits excellent deep hydrogenation activity under mild condition (T = 483 K, P = 3.0 MPa), and that it is more active than either Ni/MCM41 or Mo2N/MCM41 catalyst.

Enhanced Selectivity to Decalin in Naphthalene Hydrogenation under Supercritical Carbon Dioxide

Abstract A charcoal-supported rhodium catalyst was highly active and selective to decalin for the hydrogenation of naphthalene at very low temperature (333 K) under supercritical carbon dioxide.

Factors influencing selectivity in naphthalene hydrogenation over Au- and Pt–Au-supported catalysts

The effects of the support (γ-Al 2O 3 and SiO 2) and of the preparation method (the reduction of metal precursors by ethanol in the presence of polyvinylpyrrolidone (PVP) versus impregnation (IMP)) on the activity and selectivity of the Au and Pt–Au catalysts in naphthalene hydrogenation ( P = 2.0 MPa, T = 448 K, WHSV = 45.7 h −1) were studied. The physico-chemical characteristics of the catalysts were evaluated by X-ray diffraction, N 2 adsorption–desorption isotherms, DRIFT spectroscopy of the adsorbed CO, thermogravimetric (TG) and X-ray photoelectron spectroscopy techniques. Activity data for the target reaction showed that the SiO 2-supported catalysts are slightly better than the γ-Al 2O 3-supported counterparts. The monometallic Au/Al catalyst prepared by the IMP method displayed comparable selectivity but larger activity (mmol s −1 moles Au(Pt) −1) than its homologue prepared by the PVP method. As derived from X-ray line broadening analysis, this is due to much better dispersion of gold particles when using the IMP method. For SiO 2-supported catalysts prepared by PVP method, the initial activity followed the trend: 1Au > 1Pt–1Au > 2Pt. Both the monometallic Au/Si and 2Pt/Si exhibited quick deactivation contrary to the binary 1Pt–1Au/Si-pvp sample exhibiting higher activity at long time on stream. In this sample a synergy effect between Pt and Au was attributed to Pt 50Au 50 alloy formation. The factors controlling the selectivity in naphthalene hydrogenation on gold catalysts are discussed.

Treatment of the Carbon Nanofiber Surfaces in Mixed Concentrated HNO3-H2SO4 and the Catalytic Activity of Supported Pd-Pt for Naphthalene Hydrogenation

Treatment of the Carbon Nanofiber Surfaces in Mixed Concentrated HNO3-H2SO4 and the Catalytic Activity of Supported Pd-Pt for Naphthalene Hydrogenation

Cetane improvement of diesel with a novel bimetallic catalyst

Bimetallic Pd Pt (Pd/Pt mol ratio = 4/1) catalysts supported on a mesoporous aluminosilicate (Si/Al mol ratio = 20) were prepared by direct liquid crystal templating and using three different means of metals incorporation (direct incorporation in the synthesis gel, impregnation, and ion exchange). The method of incorporation affects the accessibility of the metal surface: with impregnation and ion exchange, intermetallic Pd Pt particles of uniform size are formed, compared to the particles of segregated metal and alloy of different sizes obtained by direct incorporation. Catalysts are characterized by adsorption of nitrogen and hydrogen, and using X-ray photoelectron and extended X-ray absorption fine structure spectroscopies. The activity of the impregnated PdPt catalyst was investigated in naphthalene hydrogenation at atmospheric pressure and at 6.0 MPa in the temperature range from 260 to 340 °C. Using a real diesel feedstock in an industrial microplant, the activity of the PdPt catalyst is higher than that of a state-of-the-art reference, giving 90.0% of aromatics saturation and an 8 points cetane index increase at 280–300 °C. Nonselective cracking products are C 7–C 10 naphthenes, and, at 325 °C, represent less than 10% product volume. Sulfur poisoning restricts catalyst reactivity mainly to saturation of aromatic molecules, with only limited ring-opening activity, but the final product has a density of 0.840 g cm −3 and a maximum distillation temperature (T95 max) of 354 °C and contains less than 3% of polyaromatics, in respect of future European legislation on road diesel.

AuPd alloy formation in Au-Pd/Al 2O 3 catalysts and its role on aromatics hydrogenation

Alumina-supported bimetallic Au-Pd catalysts were prepared by the simultaneous reduction of palladium and gold precursors by ethanol in the presence of the polyvinylpyrrolidone (PVP) and classical incipient wetness co-impregnation method (iwi). The catalysts were characterized by a variety of techniques (AAS, N 2 adsorption–desorption, XRD, TEM, CO chemisorption, TGA, FTIR-CO, DRIFTS-NH 3, and XPS). According to X-ray diffraction measurements and FTIR-CO spectra, an AuPd alloy formed on the sample prepared by the PVP method, whereas distinct phases of gold and palladium metals formed on the iwi samples. The effect of the presence of the AuPd alloy on the catalytic activity was investigated in the simultaneous hydrogenation (HYD) of toluene (T) and naphthalene (NP) in the presence of dibenzothiophene (DBT) at P = 5.0 MPa, T = 523 K, WHSV = 41.2 h −1. Under the selected conditions, all the catalysts were resistant to poisoning with 113 ppm of S (as DBT). The enhancement in activity observed for the sample prepared by PVP method as compared to those prepared by impregnation is related to the geometric effect resulting from the dilution of the Pd ensemble in the AuPd alloy and also to the presence of smaller Pd 0 particles.

Hydrogenation and hydrogenolysis/ring-opening of naphthalene on Pd/Pt supported on zirconium-doped mesoporous silica catalysts

Pd/Pt (0.5, 1.0, and 2.0 wt%) supported on mesoporous Si/Zr MCM-41-type catalysts have been investigated in the hydrogenation of naphthalene under pressure, chosen as the probe reaction for the hydrotreating of light cycle oil fractions, in order to optimize the amount of active phase. On increasing the percentage of Pd/Pt, the productivity in decalins increased, while those in hydrogenolysis/ring-opening and cracking compounds showed an opposite trend. The sample with 1 wt% of Pd/Pt may be considered the best choice, considering both hydrogenation and hydrogenolysis/ring-opening activity. Finally, adding increasing amounts of dibenzothiophene in the feed caused a decrease in the activity, although this deactivation was largely reversible.

Deep aromatics hydrogenation in the presence of DBT over Au–Pd/γ-alumina catalysts

Alumina-supported Pd, Au and Au–Pd catalysts were investigated for the simultaneous hydrogenation (HYD) of naphthalene (NP) and toluene (T) in the presence of dibenzothiophene (DBT). The nature of supported Au, its resistance against S-poisoning when applied along with Pd in the hydrogenation of aromatics was studied. Additionally, the effect of two kinds of γ-alumina (A(N) and A(S)) with different textural properties on the structure and performance of the catalysts was evaluated. Irrespectively of the support used, all the catalysts showed resistance to S-poisoning and their activity followed an order of NP > T > DBT. For hydrogenation of naphthalene, the specific reaction rates normalized to Pd loading follows trend: Au–Pd/ A ( N ) ≫ Au – Pd /A(S) > Pd(A(N) > Pd/A(S). The higher activity in the hydrogenation of naphthalene of the separate Au 0 and Pd 0 phases on a type-N alumina support with respect to those supported on a type-S alumina was related to a more homogeneous dispersion of Pd 0 and Au 0 crystallites and a lower extent of coke formation. Under an excess of hydrogen, the monometallic gold catalysts did not show any activity in the HYD of toluene. However, the Au catalysts showed over-hydrogenation of NP to decalin, in contrast with the performance of the Pd and Au–Pd samples. This behaviour can be exploited to avoid the over-hydrogenation of naphthalene by using the bimetallic Au–Pd formulation.

Pillar effects in MoS 2 catalysts supported on Al and Zr pillared clays in a hydrotreatment reaction : A preliminary study

Molybdenum (Mo) supported on aluminum-pillared clay (Al-PILC) and zirconium-pillared clay (Zr-PILC) with contents of 0.6, 1.4 and 2.8 atoms of Mo/nm 2 were prepared and tested in the hydrogenation (HYD) of naphthalene (NP). It was found that the molybdenum sulfide (MoS 2) catalysts supported on Zr- pillared clays were more active than the samples supported on Al-pillared clays and catalysts supported on alumina. The catalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis, nitrogen adsorption and transmission electron microscopy (TEM). Characterization analysis clearly pointed out to a close interaction of MoS 2 with ZrO 2 in the pillared clays. Therefore, the highest hydrogenation activities can be related to the presence of an interaction of MoS 2 with ZrO 2, probably with a different electronic interaction between the active phase and the support, than that reported for the MoS 2/Al 2O 3 system.