Strong Acid Centers Research Articles

Pt-Cu/CeO2-Al2O3 with Honeycomb-Like Structure Towards Catalytic Cracking of RP-3 and Anti-Wear Application

ABSTRACT Generally, thermal barrier and wear seriously affect flight safety by deforming or disabling the inner surface of the engine and outer surface of the vehicle of supersonic aircraft. In this study, we developed a bimetallic supported composite catalyst coating which can simultaneously eliminate the “thermal barriers” and improve the wear resistance. The bimetal-loaded composite catalysts (Pt-Cu@CeO2-Al2O3) coating was obtained by co-precipitation method. The catalytic cracking for RP-3 and wear resistance of composite catalyst coatings were evaluated via thermal cracking and friction experiments. The simulated catalytic cracking experiment results show that when n(Ce): n(Al) = 1:1, the composite catalyst exhibits the highest catalytic activity, which results from the largest specific surface area and proportion of strong acid centers. Meanwhile, under lower temperature conditions, the gas production rate of RP-3 catalytic cracking is increased by 915% (550 ℃) and 186% (600 ℃) compared with the thermal cracking. Meanwhile, the low frictional coefficient of 0.533 of the catalyst coating also indicates the satisfied wear resistance. This research provides useful information for the creation of a safer flying environment and the extension of the service life of supersonic aircraft.

Selective and Controllable Cracking of Polyethylene Waste by Beta Zeolites with Different Mesoporosity and Crystallinity.

Waste plastics bring about increasingly serious environmental challenges, which can be partly addressed by their interconversion into valuable compounds. It is hypothesized that the porosity and acidity of a zeolite-based catalyst will affect the selectivity and effectiveness, enabling a controllable and selective conversion of polyethylene (PE) into gas-diesel or lubricating base oil. A series of embryonic, partial- and well-crystalline zeolites beta with adjustable porosity and acidity are prepared from mesoporous SBA-15. The catalysts and catalytic systems are studied with nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and adsorption kinetics and catalytic reactions. The adjustable porosity and acidity of zeolite-beta-based catalysts achieve a controllable selectivity toward gas-diesel or lubricating base oil for PE cracking. With a catalyst with mesopores and appropriate acid sites, a fast escape and reduced production of cracking of intermediates are observed, leading to a significant fraction (88.7%) of lubricating base oil. With more micropores, a high acid density, and strong acid strength, PE is multiply cracked into low carbon number hydrocarbons. The strong acid center of the zeolite is confirmed to facilitate significantly the activation of hydrogen (H2),and, an in situ ammonia poisoning strategy can significantly inhibit hydrogen transfer and effectively regulate the product distribution.

PRODUCTION OF DIISOPROPYL ETHER IN THE PRESENCE OF MODIFIED HETEROPOLYACID CATALYSTS CONTAINING TITANIUM OXIDE

The catalytic activity of titanium dioxide and its analogs modified with formoformolybdenum heteropoly acid was studied in the conversion of isopropyl alcohol. It was found that adding 10% phosphoformolybdenum heteropoly acid to titanium dioxide increased the catalyst's stability and its selectivity for diisopropyl ether by more than 1.5 times. It is suggested that the formation of diisopropyl ether in the presence of unmodified titanium dioxide occurs via the fusion mechanism, while in the presence of modified titanium dioxide, it occurs via the shock mechanism. The change in the mechanism of diisopropyl ether formation is associated with a shift in the distribution of acid-base active centers: before modification, strong and weak Lewis acid centers and Bronsted base centers are present on the surface of titanium dioxide, and the introduction of the modifier blocks strong Bronsted base centers, forming a new type—Bronsted basic centers composed of oxygen atoms. Keywords: isopropyl alcohol, catalytic properties, phospho-libdeno heteropoly acid, fusion mechanism, shock mechanism.

Ce-modified USY zeolite catalysts for catalytic oxidation of chlorinated VOCs: Effect of the location of CeO2 and its synergistic effect with USY zeolite

The catalytic behavior of a catalyst for chlorine-containing volatile organic compounds (CVOCs) oxidation largely depends on the synergistic interaction between the oxidizing and acidic sites. In the present work, two catalysts with different distributions of CeO2 on the inner and outer surfaces of 4.0Ce-USY-ex and 4.0Ce-USY-dp (USY zeolite) were prepared respectively by ion exchange and deposition methods, with a purpose of finding out how the location of the oxidation sites (CeO2) influence its synergistic effect with the acidic sites of zeolite. The results show that 4.0Ce-USY-ex is much more active for catalytic degradation of 1,2-dichloroethane (DCE), while 4.0Ce-USY-dp catalyst exhibit higher catalytic degradation activity for other structured CVOCs (dichloromethane (DCM), trichloroethylene (TCE), chlorobenzene (CB)). CeO2 in 4.0Ce-USY-ex catalyst mainly disperses in the pore channels of USY zeolite, and there are many strong acid centers on the surface, which is conducive to the dechlorination conversion of CVOCs. However, CeO2 in 4.0Ce-USY-dp catalyst is mainly distributed on the outer surface of USY and has strong oxidation ability, which contributes to the deep oxidation of CVOCs. Moreover, the presence of a large number of strong acid centers on the catalyst surface of 4.0Ce-USY-ex catalysts leads to severe accumulation of surface carbon species and significantly decreases its stability towards DCE. However, a large number of active oxygen species on the surface of 4.0Ce-USY-dp and CeO2 catalysts are beneficial to the deep oxidation of DCE, reducing the formation of surface carbon and thus improving the stability of the catalyst. Thus, the influence of the location of the oxidation sites on its synergistic effect with the acidic sites was established in the present work, which could provide some new ideas for the rational design of CVOCs degradation catalyst with appropriate distribution of active sites.

XeF2 Coordination Complexes of the [BrO2]+ Cation, [O2Br(FXeF)n][AsF6] (n = 1, 2) and [O2Br(FXeF)2][SbF6]; Their Syntheses and Structural Characterizations.

The syntheses and structural characterizations of the first XeF2 coordination complexes of the [BrO2]+ cation are described. The reactions of [BrO2][PnF6] (Pn = As, Sb) with XeF2 in anhydrous HF solvent yield the salts [O2Br(FXeF)n][AsF6] (n = 1, 2) and [O2Br(FXeF)2][SbF6], which were characterized by low-temperature (LT) Raman spectroscopy and single-crystal X-ray diffraction (SCXRD). The XeF2 ligands and [PnF6]- coordinate to the Lewis acidic [BrO2]+ cation through primarily electrostatic BrV---FXe σ-hole bonds that result from coordination of the F atoms into regions of high positive electrostatic potential on the Br(V) atom and have bond trajectories that avoid the stereoactive valence electron lone-pair of Br(V). The complexes and their structural characterizations by LT Raman spectroscopy and SCXRD significantly extend the coordination chemistry of Br(V) and provide rare examples of a noble-gas difluoride coordinated to a strong oxidant main-group Lewis acid center.

Synthesis of [B,Al]-EWT-Type Zeolite and Its Catalytic Properties

EWT zeolite belongs to ultra-large pore zeolite with the 10MR and 21MR channels, which has good thermal stability, certain acid strength and good application prospects in petroleum refining and petrochemical reactions. However, EWT zeolite has fewer medium/strong acid sites, especially Brönsted acid sites, which makes it difficult to apply to acid-catalyzed reactions. The regulation of acid amount and distribution was achieved by boron and aluminum substitution into the siliceous framework of EWT. The physico-chemical properties of the samples were characterized by XRD, SEM, N2 adsorption-desorption, XRF, ICP, Py-IR, NH3-TPD and 11B & 27Al & 29Si MAS NMR. The results show that quantities of boron and aluminum elements can occupy the framework of [B,Al]-EWT to increase the density of medium and strong acid centers, with more acidity and Brönsted acid centers than EWT zeolite. In the reaction of glycerol with cyclohexanone, the conversion of the sample (U-90-08-10/U-90-H-HCl) is significantly higher than that of the EWT sample, approaching or exceeding the Beta zeolite. A catalytic activity study revealed a direct correlation between the Brönsted acidic site concentration and the activity of the catalyst. The U-90-08-10-H catalyst was also considerably stable in the catalytic process. This work shows, for the first time, that extra-large pore zeolites can be used in industrial acid-catalytic conversion processes with excellent catalytic performance.

ZSM-5 as a support for Ru-containing catalysts of levulinic acid hydrogenation: Influence of the reaction conditions and the zeolite acidity

Levulinic acid (LA) is a substance, which can be obtained from cellulosic biomass and hydrogenated to gamma-valerolactone (GVL) – important platform chemical. This work describes the study of a ruthenium-containing catalysts synthesized by the impregnation of HZSM-5 having different silicate modulus (40, 80 or 400) with ruthenium precursor, which resulted in formation of oxidized Ru(III) and Ru(IV) species on the catalyst surface. Synthesized catalysts allowed more than 98% of LA conversion for 60 min of the reaction and 100% GVL selectivity while working at relatively mild conditions (100 °C, 1 MPa of H2) in aqueous medium. It was demonstrated that the observed catalytic activity mainly depends on two factors: (i) concentration of strong Lewis acid centers on the catalyst surface and (ii) surface content of RuO2, since the synthesized catalysts needed no preliminarily activation procedure.

An Al-sol gelation strategy for the synthesis of robust hierarchical SAPO-34 with enhanced ethylene selectivity

It's significance in enhancing the ethylene selectivity of MTO, however the partial regeneration and metal modification methods would reduce the lifetime of SAPO-34, and it's necessary to develop a method to simultaneously improve the ethylene selectivity and catalytic stability. Herein, an industrial aluminum sol gelation strategy was reported, the influences of the pH value (2.8–4.0), gelation temperature (40–80 °C), and Al species were detailed studied. The SAPO-34 crystals can partially be eroded by the Al gel, and intra-crystalline mesopores (5.2–6.4 nm) can be created. However, aluminum species in the sol can be adsorbed, and the nAl:(nP + nSi) of the catalyst increased from 0.86 to 0.96–1.32. Comparatively, the erosion and adsorption of Al species were more notable under higher pH value and gelation temperature conditions. Furthermore, the gelation can prevent the hydration of the crystals, but the isolated silicon species can be reassembled to silicon islands, and the strong acid centers increased from 0.45 mmol NH3/g to 0.54–0.69 mmol NH3/g. Although more coke can be brought about by the increased strong acids, the intra-crystalline diffusion limitation can be released by the mesopores, and the catalytic stability of SAPO-34 can be better retained. More importantly, the geometric effect has been intensified by the increased coke, and a significant increase (1.6–4.7%) in the initial ethylene selectivity and a slightly decrease (0.1–1.4%) in the selectivity of propylene and butenes was achieved, leading to enhanced selectivity of ethylene and propylene (SEP, 86.6%), light olefins selectivity (SLO, 94.6%), and ratio of ethylene to propylene (C2=:C3=, 1.44), especially under higher gelation temperature. The gelation strategy is efficient in enhancing the ethylene selectivity and improving the catalytic stability of SAPO-34, and it can be applied in the preparation of industrial MTO catalyst.

The Use of WO3-ZSM-5 Zeolites in the Dehydration of Monosaccharides

In this work, a procedure was developed for the synthesis of WO3-containing catalysts based on zeolites of the ZSM-5 type. Zeolites with different Si/Al ratios and different numbers of acid sites were used: ZSM-5-CVM, ZSM-5-CVN and ZSM-5-Acros. The synthesized catalysts were characterized and tested in the reaction of the conversion of fructose and glucose to 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA). It was shown that the introduction of tungsten (VI) oxide into the composition of ZSM-5 leads to a noticeable increase in the number of active acid sites on the catalyst surface, which plays an important role in the reaction. In particular, the total concentration of weak and strong Bronsted acid centres for ZSM-5-Acros was 0.057 mmol/g; after the modification of zeolite WO3, the concentration of acid sites increased to 0.575 mmol/g. As a result, the activity of the catalysts in the reaction of dehydration of monosaccharides and rehydration of 5-HMF increased sharply. The results of the study show the promise of using zeolites of the ZSM-5 type, modified with tungsten oxide (VI), in the conversion of biomass to platform chemicals.

Bifunctional Metal-Organic Layers for Tandem Catalytic Transformations Using Molecular Oxygen and Carbon Dioxide.

Tandem catalytic reactions improve atom- and step-economy over traditional synthesis but are limited by the incompatibility of the required catalysts. Herein, we report the design of bifunctional metal-organic layers (MOLs), HfOTf-Fe and HfOTf-Mn, consisting of triflate (OTf)-capped Hf6 secondary building units (SBUs) as strong Lewis acidic centers and metalated TPY ligands as metal active sites for tandem catalytic transformations using O2 and CO2 as coreactants. HfOTf-Fe effectively transforms hydrocarbons into cyanohydrins via tandem oxidation with O2 and silylcyanation whereas HfOTf-Mn converts styrenes into styrene carbonates via tandem epoxidation and CO2 insertion. Density functional theory calculations revealed the involvement of a high-spin FeIV (S = 2) center in the challenging oxidation of the sp3 C-H bond. This work highlights the potential of MOLs as a tunable platform to incorporate multiple catalysts for tandem transformations.

Novel WO3/SO42--ZrO2–TiO2 double bridge coordination catalyst hfor oxidation of cyclohexene

A solid super acid WO3/SO42--ZrO2–TiO2 catalyst was prepared with adjustable acidity via double bridge connection strategy for oxidation of cyclohexene (CHE) to adipic acid (AA). XRD, SEM and N2 adsorption-desorption isotherm indicated that WO3 was successfully decorated and was highly dispersed on SO42--ZrO2–TiO2 surface. An obvious stretching vibration peak (1125-1055 ​cm−1) in FT-IR illustrated that connection effect between SO42− and ZrO2–TiO2 was double bridge connection. NH3-TPD profile appeared a strong acid center peak (516 ​°C), while this center of solid super acid catalyst could reduce decomposition rate of H2O2 directly, and increase reaction time between CHE and H2O2 meanwhile. The marked catalytic performance was attributed to the synergistic effect between WO3 and SO42--ZrO2–TiO2. DFT calculation was employed to further analyze reaction process and system energy.

The impact of preparation route on the performance of silver dodecatungstophosphate/β zeolite catalysts in the ethylene production

Heteropolyacids and their salts comprise catalytic centers for the production of ethylene, one of the most important constituents in the chemical industry. The paper emphasizes different synthesis routes of hybrid materials consisting of dodecatungstophosphoric acid silver salt (AgPW) and β zeolite—stepwise wet impregnation, silver-exchange in β zeolite, and dry mixing of precursors. Composite preparation procedures induced minor effects on the weak acid sites, while strong acid sites were increased significantly. β/AgPW composites prepared by two-steps wet impregnation and ion-exchange procedures have strong acid sites content and total acidity higher in comparison to the pure AgPW salt and β zeolite. This is a result of precursors synergetic effect—cumulative strong acidic sites are generated in the presence of well-dispersed Keggin ions on the zeolite network. Composite samples with a higher content of strong acid centers exhibit higher conversion in the ethanol dehydration reaction, i.e., the ion-exchanged βAgPW sample has attained a conversion over 81%, while the wet-impregnated sample has a significant 86%. The distribution and presence of AgPW active phase are found to be crucial for both stable conversion and high selectivity results in ethylene production from ethanol, which is regarded as one of the most significant processes in environmental and sustainable industrial chemistry.Graphic abstract

Supported Silver Nanoparticles as Catalysts for Liquid-Phase Betulin Oxidation.

Herein, it has been shown that betulin can be transformed into its biologically active oxo-derivatives (betulone, betulinic and betulonic aldehydes) by liquid-phase oxidation over supported silver catalysts under mild conditions. In order to identify the main factors determining the catalytic behavior of nanosilver catalysts in betulin oxidation, silver was deposited on various alumina supports (γ-alumina and boehmite) using deposition–precipitation with NaOH and incipient wetness impregnation methods, followed by treatment in H2 or O2. Silver catalysts and the corresponding supports were characterized by X-ray diffraction, nitrogen physisorption, inductively coupled plasma optical emission spectroscopy, photoelectron spectroscopy and transmission electron microscopy. It was found that the support nature, preparation and treatment methods predetermine not only the average Ag nanoparticles size and their distribution, but also the selectivity of betulin oxidation, and thereby, the catalytic behavior of Ag catalysts. In fact, the support nature had the most considerable effect. Betulin conversion, depending on the support, increased in the following order: Ag/boehmite < Ag/boehmite (calcined) < Ag/γ-alumina. However, in the same order, the share of side reactions catalyzed by strong Lewis acid centers of the support also increased. Poisoning of the latter by NaOH during catalysts preparation can reduce side reactions. Additionally, it was revealed that the betulin oxidation catalyzed by nanosilver catalysts is a structure-sensitive reaction.

Promoting the selective catalytic oxidation of diethylamine over MnOx/ZSM-5 by surface acid centers

Herein, we demonstrated the selective catalytic oxidation of diethylamine to N2 over MnOx/ZSM-5 catalysts. It was found that oxidation activity of diethylamine over MnOx/ZSM-5 catalysts increased when the loading of Mn increased, but the N2 selectivity decreased at 420 °C obviously. MnOx/ZSM-5(360) catalysts showed higher oxidation activity of diethylamine than MnOx/ZSM-5(18) catalysts with equivalent Mn loading, which was ascribed to the presence of MnOx species easily reduced and enriched on ZSM-5(360) support surface. However, MnOx/ZSM-5(18) catalysts containing moderate and strong surface acid centers in addition to the weak acid centers gave significantly higher N2 selectivity than MnOx/ZSM-5(360) catalysts possessing only weak surface acid centers. 20MnOx/ZSM-5(18) catalyst had relatively high oxidation activity of diethylamine and N2 selectivity, of which the lowest reaction temperature for diethylamine conversion at 98% (T98) is 240 °C and the N2 selectivity is exceeding 95.5% at 420 °C. Furthermore, 20MnOx/ZSM-5(18) catalyst showed wider temperature window (ΔT = 180 °C) with N2 selectivity over 95% than 20MnOx/ZSM-5(360) catalyst (ΔT = 80 °C). It can be concluded that the easily reduced and surface enriched MnOx species are favorable for the oxidation of diethylamine, the moderate and strong surface acid centers are beneficial to activation of diethylamine and the generation of N2.

Catalytic Performance of Bulk and Al2O3-Supported Molybdenum Oxide for the Production of Biodiesel from Oil with High Free Fatty Acids Content

Non-edible vegetable oils are characterized by high contents of free fatty acids (FFAs) that prevent from using the conventional basic catalysts for the production of biodiesel. In this work, solid acid catalysts are used for the simultaneous esterification and transesterification with methanol of the FFAs and triglycerides contained in sunflower oil acidified with oleic acid. Molybdenum oxide (MoO3), which has been seldom considered as a catalyst for the production of biodiesel, was used in bulk and alumina-supported forms. Results showed that bulk MoO3 is very active for both transesterification and esterification reactions, but it suffered from severe molybdenum leaching in the reaction medium. When supported on Al2O3, the MoO3 performance improved in terms of active phase utilization and stability though molybdenum leaching remained significant. The improvement of catalytic performance was ascribed to the establishment of MoO3-Al2O3 interactions that favored the anchorage of molybdenum to the support and the formation of new strong acidic centers, although this effect was offset by a decrease of specific surface area. It is concluded that the development of stable catalysts based on MoO3 offers an attractive route for the valorization of oils with high FFAs content.

Enhanced electrochemical performance of Li1.18Ni0.15Co0.15Mn0.52O2 cathode modified with aluminosilicate solid acid

Li-rich cathode material Li1.18Ni0.15Co0.15Mn0.52O2 is prepared by a sol–gel method and modified with aluminosilicate solid acid (Al2O3·SiO2) via an ultrasonic impregnation process. Compared with the pristine and Al2O3/SiO2-sole-modified counterparts, the Al2O3·SiO2 coating layer with high acid center strength on Li1.18Ni0.15Co0.15Mn0.52O2 material exhibits overall improved electrochemical performance. Galvanostatic charge–discharge tests at the current density of 200 mA g−1 displays the highest capacity retention of 72.5% and voltage retention of 95.1% after 200 cycles for Al2O3·SiO2-coated material. Meanwhile, a high rate capability of 99.2 mAh g−1 after 300 cycles is obtained with a good retention of 65.7% at the current density of 1 A g−1. The analysis of dQ/dV plots indicates the strong acid center strength of Al2O3·SiO2 coating layer on Li1.18Ni0.15Co0.15Mn0.52O2 cathode material can be favor of suppressing the voltage decay and reducing the side reactions between the electrode and the electrolyte.

Key Stages of the Formation of AlPO4-11 via Crystallization of Aluminophosphate Gel Prepared with Boehmite

The one-dimensional channel pore system and the moderately strong acid centers inherent in aluminophosphate (AlPO4-11) and silicoaluminophosphate (SAPO-11) molecular sieves make them promising catalyst for hydroisomerization of higher n-paraffins. However, the mechanism of crystallization of these materials is not well understood as yet. XRD,27Al and31P MAS NMR, lowtemperature adsorption-desorption of nitrogen, and SEM techniques were used for the first time for studying the stage crystallization of aluminophosphate AlPO4-11 for commercial boehmite based aluminium source. AlPO4-11 was shown to form via an intermediate phase based on layered crystalline aluminophosphate. It was established that highly crystalline and phase-pure AlPO4-11 was formed at 200 °C during 6 to 24 hours. When the crystallization at 200 °C lasted for more than two days, AlPO4-11 turned into non-porous cristobalite. The results obtained will be used for developing methods for deliberate control of the phase composition and crystallinity of industrially important silicoaluminophosphate sieves SAPO-11 with required properties to develop promising catalysts based thereon for large-scale processes of hydroisomerization of n-paraffins.

The study of methanol aromatization on transition metal modified ZSM-5 catalyst

Abstract In this article, transition metals of Cu, La and Zn were used as adjuvant to prepare modified HZSM-5 by impregnation method. The catalysts were characterized by XRD, BET, NH3-TPD and Py-IR to reveal the microstructure and acid property. The catalysis performances of methanol aromatization of catalysts were investigated in a fixed-bed reactor. The results show that the strength and distribution of acid center of these catalysts are significantly influenced by the species of transition metal. There are more mediate strong Lewis acid center in Zn modified HZSM-5 catalyst and therefore exhibits higher selectivity to aromatic, benzene, toluene and xylenes in the MTA reaction..

Formation and Acid–Base Surface Properties of Highly Dispersed η-Al2O3 Nanopowders

Highly dispersed η-Al2O3-based nanopowders have been prepared via glycine–nitrate combustion followed by heat treatment in air. The resultant materials have been characterized by X-ray diffraction, Fourier transform IR spectroscopy, scanning electron microscopy, simultaneous thermal analysis, and other techniques. We have optimized the glycine-to-nitrate ratio (G/N = 0.2) and found heat treatment conditions for combustion products (isothermal holding at a temperature of 700°C for 6 h) that allow one to obtain single- phase nanocrystalline η-Al2O3 powders with an average particle size of 5 ± 1 nm and specific surface area of 54 ± 5 m2/g. The acid–base surface properties of the η-Al2O3 nanopowder have been analyzed using pyridine sorption–desorption processes as an example. The specific concentrations of weak, intermediate, and strong Lewis acid centers on the surface of the η-Al2O3 nanocrystals have been shown to markedly exceed those on the surface of commercially available γ-Al2O3 (A-64). The synthesized nanopowders can thus be used as effective supports of acid catalysts.

Kinetics of thiophene hydrodesulfurization over a supported Mo–Co–Ni catalyst

In this study, the kinetics of thiophene (TH) hydrodesulfurization (HDS) over the Mo–Co–Ni-supported catalyst was investigated. Trimetallic catalyst was synthesized by pore volume impregnation and the metal loadings were 11.5 wt % Mo, 2 wt % Co, and 2 wt % Ni. A large surface area of 243 m 2 /g and a relatively large pore volume of 0.34 cm 3 /g for the fresh Mo–Co–Ni-supported catalyst indicate a good accessibility to the catalytic centers for the HDS reaction. The acid strength distribution of the fresh and spent catalysts, as well as for the support, was determined by thermal desorption of diethylamine (DEA) with increase in temperature from 20 to 600 °C. The weak acid centers are obtained within a temperature range between 160 and 300 °C, followed by medium acid sites up to 440 °C. The strong acid centers are revealed above 440 °C. We found a higher content of weak acid centers for fresh and spent catalysts as well as alumina as compared to medium and strong acid sites. The catalyst stability in terms of conversion as a function of time on stream in a fixed bed flow reactor was examined and almost no loss in the catalyst activity was observed. Consequently, this fact demonstrated superior activity of the Mo–Co–Ni-based catalyst for TH HDS. The activity tests by varying the temperature from 200 to 275 °C and pressure from 30 to 60 bar with various space velocities of 1–4 h −1 were investigated. A Langmuir–Hinshelwood model was used to analyze the kinetic data and to derive activation energy and adsorption parameters for TH HDS. The effect of temperature, pressure, and liquid hourly space velocity on the TH HDS activity was studied.