Dehydrogenation Of Tetralin Research Articles

Hydrocracking of polyethylene to hydrocarbon fuels over Pt/USY catalysts: Assessment of the hydrogen donors

Hydrocracking is an effective approach to convert waste polyolefins into value-added fuels. Efficient hydrogen transfer from the hydrogen donors to the polyolefins is crucial to the hydrocracking process. In this work, we evaluated the hydrocracking effectiveness of different hydrogen donors (H2, tetralin and H2+tetralin) in polyethylene hydrocracking over a Pt/USY catalyst by analyzing and comparing the product distribution under varied H circumstances. The hydrocracking pathway using gaseous (H2) and liquidous (tetralin) hydrogen donors was proposed. The results show that the most effective H-donor for fuel oil production is H2, which yielded 65.8% oil abundant in C6–C12 range after reaction at 350 °C for 60 min. Tetralin can be dehydrogenated by Pt/USY catalyst to provide active H for PE hydrocracking, but the hydrocracking effectiveness is inferior to that using H2 because of catalyst deactivation caused by the by-products such as naphthalene from tetralin dehydrogenation. For the same reason, using H2+tetralin as H-donors is not as efficient for oil production as using sole H2 as H-donor. The reaction pathway of PE hydrocracking over Pt/USY catalyst using H2 and tetralin as the H-donor is different. Hydrocracking with H2 follows the hydrogenolysis pathway. When tetralin is presented, the hydrogenolysis pathway is cut off, followed by the thermal reactions between tetralin and PE, which inhibits PE cracking and decreases oil production.

過熱液膜方式・テトラリン脱水素触媒反応の熱解析と活性要因

過熱液膜方式・テトラリン脱水素触媒反応の熱解析と活性要因

The effects of Fe2O3 and MoS2 on the catalytic activation pathway of hydrogen sources during direct coal liquefaction

Direct coal liquefaction (DCL) can be highly promoted by catalysts due to the acceleration of hydrogen activation. There are two pathways of activation for H2 during the process of DCL. One is that H2 dissolves in the liquid phase and then transfers to coal after splitting (molecular hydrogen), and the other is dissolved H2 is hydrogenated with solvent and then transferred from solvent to coal (transfer hydrogen). In addition, hydrogen in the solvent molecules can be supplied to coal (solvent hydrogen). The effects of two catalysts, Fe2O3 and MoS2, on the activation of molecular hydrogen, transfer hydrogen, and solvent hydrogen during DCL were investigated. Herein, we conducted a series of experiments, including DCL with H2-decalin, DCL with N2-tetralin, tetralin dehydrogenation, naphthalene hydrogenation, and DCL with H2-tetralin. The catalyst and products were characterized by XRD, GC, GC-MS, 1H NMR and TG. Quantum chemistry reveals the catalyst effect on hydrogen activation. The catalytic performance and different hydrogen consumption reveal that the Fe2O3 catalyst primarily activates molecular hydrogen, and MoS2 activates all three kinds of hydrogen. This work not only reveals the catalyst effect on hydrogen activation but also gives light to the design of an appropriate and effective catalyst for DCLs.

Hydrogenation and Dehydrogenation of Tetralin and Naphthalene to Explore Heavy Oil Upgrading Using NiMo/Al2O3 and CoMo/Al2O3 Catalysts Heated with Steel Balls via Induction

This paper reports the hydrogenation and dehydrogenation of tetralin and naphthalene as model reactions that mimic polyaromatic compounds found in heavy oil. The focus is to explore complex heavy oil upgrading using NiMo/Al2O3 and CoMo/Al2O3 catalysts heated inductively with 3 mm steel balls. The application is to augment and create uniform temperature in the vicinity of the CAtalytic upgrading PRocess In-situ (CAPRI) combined with the Toe-to-Heel Air Injection (THAI) process. The effect of temperature in the range of 210–380 °C and flowrate of 1–3 mL/min were studied at catalyst/steel balls 70% (v/v), pressure 18 bar, and gas flowrate 200 mL/min (H2 or N2). The fixed bed kinetics data were described with a first-order rate equation and an assumed plug flow model. It was found that Ni metal showed higher hydrogenation/dehydrogenation functionality than Co. As the reaction temperature increased from 210 to 300 °C, naphthalene hydrogenation increased, while further temperature increases to 380 °C caused a decrease. The apparent activation energy achieved for naphthalene hydrogenation was 16.3 kJ/mol. The rate of naphthalene hydrogenation was faster than tetralin with the rate constant in the ratio of 1:2.5 (tetralin/naphthalene). It was demonstrated that an inductively heated mixed catalytic bed had a smaller temperature gradient between the catalyst and the surrounding fluid than the conventional heated one. This favored endothermic tetralin dehydrogenation rather than exothermic naphthalene hydrogenation. It was also found that tetralin dehydrogenation produced six times more coke and caused more catalyst pore plugging than naphthalene hydrogenation. Hence, hydrogen addition enhanced the desorption of products from the catalyst surface and reduced coke formation.

Inductive Heating Assisted-Catalytic Dehydrogenation of Tetralin as a Hydrogen Source for Downhole Catalytic Upgrading of Heavy Oil

The Toe-to-Heel Air Injection (THAI) combined with a catalytic add-on (CAPRI, CATalytic upgrading PRocess In-situ) have been a subject of investigation since 2002. The major challenges have been catalyst deactivation due to coke deposition and low temperatures (~ 300 °C) of the mobilised hot oil flowing over the catalyst packing around the horizontal well. Tetralin has been used to suppress coke formation and also improve upgraded oil quality due to its hydrogen-donor capability. Herein, inductive heating (IH) incorporated to the horizontal production well is investigated as one means to resolve the temperature shortfall. The effect of reaction temperature on tetralin dehydrogenation and hydrogen evolution over NiMo/Al2O3 catalyst at 250–350 °C, catalyst-to-steel ball ratio (70% v/v), 18 bar and 0.75 h−1 was investigated. As temperature increased from 250 to 350 °C, tetralin conversion increased from 40 to 88% while liberated hydrogen increased from 0.36 to 0.88 mol based on 0.61 mol of tetralin used. The evolved hydrogen in situ hydrogenated unreacted tetralin to trans and cis-decalins with the selectivity of cis-decalin slightly more at 250 °C while at 300–350 °C trans-decalin showed superior selectivity. With IH the catalyst bed temperature was closer to the desired temperature (300 °C) with a mean of 299.2 °C while conventional heating is 294.3 °C. This thermal advantage and the nonthermal effect from electromagnetic field under IH improved catalytic activity and reaction rate, though coke formation increased.

Monometallic and bimetallic catalysts based on Pd, Cu and Ni for hydrogen transfer deoxygenation of a prototypical fatty acid to diesel range hydrocarbons

Bimetallic PdxNi(100-x) and PdxCu(100-x) structures of a wide compositional range supported on activated carbon were synthesised via a simple, cheap and commercially relevant method. The surface and bulk properties of both the bimetallic structures and their monometallic counterparts were determined via STEM-EDS, TEM, XPS, powder XRD, N2 porosimetry and ICP-OES. A close correlation between the XRD patterns and EDS elemental composition mapping of individual metal particles established the extent of palladium-base metal interaction in each sample. The performance of the different structures as catalysts for the selective hydrogenation and hydrodeoxygenation of oleic acid, a prototypical fatty acid, was evaluated using tetralin as a hydrogen donor. Catalysts displaying true bimetallic/alloy formation were found to improve the conversion of tetralin as compared to catalysts in which compositional segregation was observed. The PdxNi(100-x) series was found to outperform the PdxCu(100-x) catalysts in terms of hydrogen production via the dehydrogenation of tetralin, mirroring the fact that compositional segregation occurs more for the PdxCu(100-x) series than PdxNi(100-x). The hydrogen transfer deoxygenation of oleic acid over the monometallic and bimetallic catalysts was found to mirror the availability of hydrogen with those catalysts liberating more hydrogen also favouring the formation of C17 and C18 alkanes.

Characterization of direct coal liquefaction catalysts by their sulfidation behavior and tetralin dehydrogenation activity

Direct coal liquefaction (DCL) involves complex catalytic reactions and catalyst transformation. These catalyst behaviors are not well revealed and correlated with the DCL results in the past due to large errors in conventional high-pressure autoclave experiments, which are slow in heating rate and complex in product separation and quantification. To better understand transformation of DCL catalysts and evaluate their activity, this paper studies activity of seven DCL catalysts in dehydrogenation of tetrahydronaphthalene (THN or tetralin) using a high throughput method and compare the results with the catalytic activity in DCL in a conventional high-pressure autoclave. The catalysts' activities in THN dehydrogenation and in DCL are correlated with their sulfidation behaviors observed in temperature-programmed heating in a 5%H2S/H2 atmosphere. It is found that the catalysts show the same activity order in THN dehydrogenation and in DCL. The rate constant of THN dehydrogenation and coal conversion and oil yield in DCL correlate well with S content of the catalysts at reaction conditions. Regardless of the metal forms and the catalysts' preparation methods, linear trends are observed: the higher the catalysts' S content, the lower the activation energy for THN dehydrogenation, and the higher the coal conversion and oil yield in DCL. This finding provides a general role as well as easy methods for assessing the catalysts' activity in the direct coal liquefaction, i.e. the catalysts' DCL activity can be evaluated by their S contents or by their activities in THN dehydrogenation.

Upgrading of petroleum vacuum residue using a hydrogen-donor solvent with acid-treated carbon

Hydrocarbon/carbon systems can be used to perform the hydrogen transfer reaction in heavy oil upgrading, as alternatives to metal catalysts and molecular hydrogen. In this study, a system comprising a hydrogen-donor solvent (tetralin) and acid-treated activated carbon was established to evaluate its ability as a hydrogen transfer agent to upgrade a vacuum residue (VR). The use of tetralin substantially decreased coke formation from 32.7 wt% to a negligible amount in VR upgrading at 450 °C because the solvent could act as a hydrogen donor and diluent for the coke precursors. The acid-treated activated carbon accelerated dehydrogenation of tetralin through hydrogen transfer in the upgrading, resulting in a higher residue conversion and moderate coke formation. In view of the phase behavior, the hydrogen transfer reaction could also be promoted by increasing the contact between the hydrogen acceptor and donor in the supercritical medium. In the VR upgrading using the activated carbon in supercritical tetralin, complete residue conversion was achieved with 47 wt% light fractions (gas and light oil) and 6 wt% coke at 450 °C and 5.33 MPa. The results indicate that the streams available in oil refinery processes, which are rich in hydrocarbons with hydrogen-donor abilities, have great potential for use in heavy oil upgrading.

Different catalytic behaviors of Pd and Pt metals in decalin dehydrogenation to naphthalene

Decalin is more easily dehydrogenated on Pt catalyst than Pd while the dehydrogenation of tetralin is more facile on Pd than Pt.

Bimetallic AuPd Nanocluster Catalysts with Controlled Atomic Gold Distribution for Oxidative Dehydrogenation of Tetralin

A simple and versatile method for the preparation of bimetallic AuPd nanoclusters (NCs) with controlled atomic gold distributions and stabilization by poly(vinyl-2-pyrrolidone) is demonstrated. The dropwise injection of ethanolic HAuCl4 and the strong acidic reaction environment assist the control of the distribution of gold atoms on preformed Pd NCs. These bimetallic NCs are highly active and selective catalysts for the dehydrogenative aromatization of tetralin into naphthalene. Several AuPd NC catalysts have been tested, and these results demonstrate that AuPd NCs with the lowest gold content have higher catalytic activity. Characterization, including extended X-ray absorption fine structure and X-ray absorption near-edge structure analyses, reveals that AuPd NCs with the lowest gold content have more Au–Pd heterobonds, which play a key role in the dehydrogenative aromatization reaction. In contrast, transmission electron microscopy and high-resolution TEM analyses show that AuPd NCs with a greater gold content have island-like morphologies, where nanocrystalline gold is deposited on the surfaces of the Pd NCs, which reduces the number of Au–Pd bond active sites on the Pd NC surfaces. Our study reveals that tuning of the Au–Pd bond on the surface of the Pd NCs with a very low content of gold results in high synergy in catalytic activity and may be expected to be applicable to a wide variety of bimetallic NCs.

Organic syntheses by microwave selective heating of novel metal/CMC catalysts – The Suzuki–Miyaura coupling reaction in toluene and the dehydrogenation of tetralin in solvent-free media

The present study examines carbon microcoils (CMCs) as a novel support for Pt and Pd nanocatalysts and compares it with activated carbon nanoparticles as support for Pt and Pd metal deposits in two model microwave-assisted organic syntheses: (i) the Suzuki–Miyaura coupling reaction between phenylboronic acid and 1-bromo-4-methylbenzene in toluene solvent to produce 4-methyl-biphenyl and (ii) the dehydrogenation of tetralin (1,2,3,4-tetrahydronaphthalene) in solvent-free conditions. The microwave absorption capacity of the CMCs was more effective than the ACs support from the viewpoint of dielectric parameters (dielectric constant, dielectric loss, and loss tangent). Possible generation of microplasma (i.e., hot spots) on both supports that can impact on the progress of the reactions was monitored visually and photographed with a high-speed camera. Conventional heating (oil bath or heating mantles) of the Pd(Pt)/CMCs and Pd(Pt)/ACs system led to significantly lower product yields.

Microwave effect in the dehydrogenation of tetralin and decalin with a fixed-bed reactor

This study investigates the effect of microwaves on the dehydrogenation of decalin and tetralin. The reactions were studied in a fixed-bed reactor under microwave heating (MWH), and the results were compared with those under conventional heating (electrical heating) (CH). The result of this investigation showed that under the same operating conditions, increase in the conversion of tetralin in the microwave-heated system was more than that in the conventional heated system. This demonstrated the microwave effect appeared in the dehydrogenation of tetralin. In addition, the activity and stability of the catalyst also improved under MWH. The microwave effect resulted in increase in the conversion reaction of tetralin dehydrogenation by generation of a large temperature gradient from the catalyst surface to surrounding species and the subsequent mass transfer in which both vectors have direction inverted from that of CH. Such a phenomenon induced faster molecule desorption (product species) or enhancement of species transport in the system. In addition, the contiguous strong adsorption of hydrocarbon can be reduced, leading to decrease in coke deposition. Conditionally, this benefit issue particularly resulted in increase in the reaction rate in which species transport or mass diffusion is the rate-limiting step.

Enhanced conversion of tetralin dehydrogenation under microwave heating: Effects of temperature variation

Effects of temperature variation in microwave-induced system of tetralin dehydrogenation on the enhancement of reactivity were investigated. The enhancement of heating ability of Pt-supported activated carbon catalyst (Pt/AC) particle and decreasing of an existing temperature gradient (non-uniformed heat distribution) in tetralin solution under microwave heating and boiling-reflux condition were examined by three methodologies: an employment of Dewar-like insulation reactor (DIR), addition of an ionic liquid as an optional microwave absorber in the system, and optimization of the catalyst to the reactant in the reaction system. The Dewar-like insulation reactor was used to prevent heat loss in the heterogeneous solution. Under microwave heating with DIR, the reaction can be heated approximately 3°C above the normal boiling point of tetralin. In comparison to the reaction carried out in a conventional reactor, tetralin conversion increased from 31% to 56% under 190W microwave irradiation. Addition of an ionic liquid to the system to function as a heating promoter remarkably enhanced the heating rate of tetralin. However, the ionic liquid deactivated the activity of the catalyst in the reaction. Optimization of tetralin to Pt/AC catalyst in the reaction system improved heat distribution and showed an interesting result. It was found that the reaction performed under the liquid film state showed the highest tetralin conversion, 69% with the microwave irradiation for 60min.

Hydrogen production from tetralin over microwave-accelerated Pt-supported activated carbon

The hydrogen production from tetralin was carried out under microwave heating compared with conventional heating. Pt-supported activated carbon was used as a catalyst and microwave receptor in the reaction. Microwave heating increased the conversion of tetralin dehydrogenation as compared with conventional heating up to 19% at the same condition (207 °C). Moreover, the microwave reaction exhibited the lower retardation constant resulting from naphthalene adsorption on the surface of heterogeneous catalyst.

Hydrogen Production by Catalytic Dehydrogenation of Tetralin and Decalin Over Stacked Cone Carbon Nanotube-Supported Pt Catalysts

Stacked cone carbon nanotubes (SC-CNT) with a BET surface area of ∼280 m2/g were used as the support medium to prepare Pt catalysts for partial dehydrogenation of tetralin and decalin to produce pure hydrogen and naphthalene. The results show that for dehydrogenation of tetralin at 240 °C, 1.0 wt % Pt/SC-CNT is more active than 1.0 wt % Pt catalyst supported on granular carbon or carbon black (acetylene soot) and more active than 1.0 wt % Pt, Pd, or Rh supported on γ-alumina. HRTEM characterization of the used catalysts established that Pt was more highly dispersed on SC-CNT than on the other supports. At 240 °C, dehydrogenation of decalin produces hydrogen, tetralin, and naphthalene. The small amount of tetralin present in the products compared with the amount of naphthalene produced suggests that the dehydrogenation of decalin to tetralin is slower than the dehydrogenation of tetralin. cis-Decalin exhibits a higher conversion rate than trans-decalin, suggesting that the flexible geometric structure of c...

Dehydrogenation of tetralin on Pd/C and Te-Pd/C catalysts in the liquid-film state under distillation conditions

The dehydrogenation of tetralin to naphthalene in the liquid-film state on Pd/C and Te-Pd/C catalysts was investigated under reactive distillation conditions at 493 K. The conversion of tetralin was high, when observed using 0.3 g of Pd/C at a specific volume of tetralin (0.9 mL) was used, while the addition of tellurium into the Pd/C catalyst resulted in a similar high conversion using 0.3 g of Te-Pd/C with a somewhat wider volumetric range (0.8–1.1 mL) of tetralin.

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.

Behavior of Hydrogen Transfer in the Hydrogenation of Anthracene over Activated Carbon

The behavior of hydrogen transfer over activated carbon was examined through the hydrogenation of anthracene in the temperature range of 300−400 °C with three kinds of hydrogen sources: hydrogen gas, hydrogen-donor tetralin, and the combination of both. With hydrogen gas, the hydrogen transfer rate determined from the distribution of hydrogenated anthracene products increased with both hydrogen partial pressure and temperature, while in tetralin it depended on the concentration of hydrogen atoms formed on the surface of activated carbon by the dehydrogenation of tetralin and reached levels at temperatures of 350−400 °C comparable to those obtained in the same temperatures under 6.0 MPa of H2. When both hydrogen gas and tetralin were used together, the hydrogen transfer rate was higher than each one obtained separately with hydrogen gas alone or tetralin alone, but much lower than the simple sum of both rates in the range of 350−400 °C. Simultaneously, the hydrogen formation rate based on the conversion of tetralin in this case was greatly suppressed due to the presence of hydrogen gas and measured to be quite close to the corresponding hydrogen transfer rate. This indicates that the hydrogen transfer in the hydrogenation of anthracene over activated carbon mainly took place from tetralin to anthracene when both hydrogen gas and tetralin donor were used as hydrogen source together.

トリチウムおよび｀３５´Ｓトレーサー法による石炭液化反応機構の解明 鉄‐硫黄系触媒および硫黄の添加効果

Effects of addition of the catalyst (pyrrhotite) and sulfur on hydrogen transfer in liquefaction of Taiheiyo coal were investigated using tritium and 35S. The coal liquefaction was performed at the initial pressure of 5.9 MPa and at 400°C for 30 min with tetralin solvent and tritium-labelled hydrogen, with or without the synthesized pyrrhotite catalyst and sulfur (or 35S-labelled sulfur). The specific activities of tritium and 35S in the reaction products were measured with a liquid scintillation counter. Amounts of exchanged and transferred hydrogens between the gas phase and coal/solvent, were calculated from the distributions of tritium and changes in the composition of products.In the reaction with tritiated hydrogen and solvent, the dehydrogenation of tetralin to produce naphthalene and the hydrogen exchange reaction between gas phase and solvent were promoted by added catalyst and sulfur. Added sulfur produced hydrogen sulfide mainly with hydrogen of solvent. A part of added sulfur participated in the sulfur exchange reaction with the pyrrhotite catalyst. In the reaction with tritiated hydrogen, solvent and coal, the hvdrogen addition and exchange to coal and liquefaction products increased with the addition of catalyst and sulfur. It was suggested the sulfur promoted the formation of tetralyl radical in the hydrogen transfer from solvent to coal.

Refined Insight in Stereochemical and Directional Features of the FeI‐Mediated Dehydrogenation of Tetralin

AbstractExperimental results demonstrate that, in the course of gas‐phase Fe+‐mediated dehydrogenation of tetralin, the metal ion sticks to the same plane of the hydrocarbon surface. The study of 5‐substituted, labeled tetralin analogues reveal the operation of an interesting substituent effect: Steric hindrance imposed by a CH3 group at C(5) deflects the metal to the more easily accessible region of C(1)/C(2); in contrast, a CH3O substituent at C(5) directs the metal ion to the more congested C(3)/C(4) region which clearly points to a coordination of Fe+ to the MeO group in the course of the haptotropic migration.