Supported Hydrodesulfurization Catalysts Research Articles

Effectiveness Study of Mesoporous Size, Acidity, and Precursor Type on Characterization of Activated Carbon as an Fe–Mo Catalyst Support for Hydrodesulfurization of Heavy Naphtha

Effectiveness Study of Mesoporous Size, Acidity, and Precursor Type on Characterization of Activated Carbon as an Fe–Mo Catalyst Support for Hydrodesulfurization of Heavy Naphtha

Melamine foam-supported CoMo catalysts with three-dimensional porous structure for effective hydrodesulfurization of thiophene

The performance of the hydrodesulfurization (HDS) catalysts is generally subjected to the characteristics of supports. In this work, the melamine foam (MF) was employed as the support for fabricating a series of three-dimensional porous (3DP) CoxMo/MF supported HDS catalysts. The properties of the obtained HDS catalysts were characterized by XRD, TG, SEM, TEM, and low-temperature N2 adsorption–desorption techniques. The characterization results demonstrated that the CoxMo/MF supported catalysts possessed the 3DP structure, in which the metal oxides were attached to the prismatic pillars of the MF framework. The activity test results illustrated that the thiophene conversion over the Co2.0Mo/MF catalyst could reach 96.96% under 1 MPa and 360 °C. The unique 3DP structure with rich meso-/macropores, low average length and average stacking of crystalline MoS2 promoted the HDS activity of the Co2.0Mo/MF catalyst. This research shows the potential application of MF support in the field of catalysis and provides the possible direction for the further development of the supported HDS catalysts.

Green synthesis of KIT-6 from water-glass as support for hydrodesulfurization catalysts, and its comparison with KIT-6 synthesized from TEOS

Abstract The potential of KIT-6 as support for hydrodesulfurization (HDS) catalysts has been demonstrated in several works. Main advantage of KIT-6 consists of more than double of surface area that is accessible for large molecules (pore diameter above 6 nm). In the synthesis of KIT-6 prevails the use of tetraethyl orthosilicate (TEOS) as silicon source, being the requirement of this alkoxide one of the main hindrance to consolidate the use of this support on industry. This work presents a green synthesis of KIT-6 and Ti-modified KIT-6 obtained from water-glass, which were used to synthesize CoMo catalysts with metal loading of 16% wt, through incipient impregnation method assisted by ultrasound. Performance of these catalysts on HDS of DBT was compared for equivalent supports synthesized from TEOS and results demonstrate that the use of water-glass for support synthesis does not affect significantly the catalytic activity, allowing thus its use for the design of HDS commercial catalysts.

Improvement of Heavy Oil Hydrodesulfurization Catalyst Support Properties by Acetic Acid Treatment

A specific type of mesopore extrudates gamma alumina was prepared; which is applied as the catalyst in the heavy oil hydrodesulfurization unit. Extrudates gamma alumina has been devised the boehmite powder; several samples have been utilized to investigate the concentration and the number of acetic acid treatment effects on the textural properties. Textural properties of catalyst support have been characterized by X-Ray Diffraction, N2-adsorption/desorption techniques, the best results were observed at 25% acetic acid after three times treatments. The active metals (3.71%Molybdenium &1.43%Nickle) have been impregnated on the catalyst support. The prepared catalyst determined by X-Ray Fluorescence, N2- adsorption/desorption, bench-scale reactor test, NH3-Temperature Programmed Desorption and Radial Strength techniques.

The surface properties of aluminated meso\u2013macroporous silica and its catalytic performance as hydrodesulfurization catalyst support

Aluminated mesoporous silica was prepared by multiple post-grafting of alumina onto uniform mesoporous SiO2, which was assembled from monodisperse SiO2 microspheres. Hydrodesulfurization (HDS) catalyst was prepared by loading Ni and Mo active components onto the aluminated uniform mesoporous SiO2, and its HDS catalytic performance was evaluated using hydrodesulfurization of dibenzothiophene as the probe reaction at 300 °C and 6.0 MPa in a tubular reactor. The samples were characterized by N2 physisorption, scanning electronic microscopy, Fourier transform infrared spectrum, X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD), 27Al nuclear magnetic resonance (27Al-NMR) and high-resolution transmission electron microscopy (HRTEM). The results showed that the Si–OH group content of SiO2 was mainly dependent on the pretreatment conditions and had significant influence on the activity of the NiMo catalyst. The surface properties of the aluminated SiO2 varied with the Al2O3-grafting cycles. Generally after four cycles of grafting, the aluminated SiO2 behaved like amorphous alumina. In addition, plotting of activity of NiMo catalysts supported on aluminated meso–macroporous silica materials against the Al2O3-grafting cycle yields a volcano curve.

Efficient hydrodesulfurization catalysts based on Keggin polyoxometalates

Bulk and supported hydrodesulfurization catalysts based on Mo and W and containing Co or Ni as promoters and phosphorus as a modifier are prepared through the polyoxometalate route using Keggin type phosphomolybdates and phosphotungstates and tested in the HDS of thiophene at 350–400°C and 1 bar pressure. The corresponding oxidic pre-catalysts retain intact Keggin structure of the parent polyoxometalates and possess Brønsted and Lewis acidity. In the course of sulfidation, the oxidic pre-catalysts transform into an active sulfidic phase with the loss of Keggin structure and catalyst acidity. Catalyst activity increases in the order of supports: SiO2<TiO2<γ-Al2O3. CoMoP/γ-Al2O3 catalyst prepared through the polyoxometalate route shows higher HDS activity and butene selectivity than industrial catalyst of comparable composition. The results indicate that polyoxometalate catalyst preparation route can be considered a performance enhancement methodology for HDS catalysis.

Hierarchization of Mordenite as NiW Sulfide Catalysts Support: Towards Efficient Hydrodesulfurization

AbstractNiW‐based catalysts were supported on Al2O3, commercial mordenite (HM), and hierarchical mordenite prepared by acid–base–acid treatment (HM–M). Their catalytic performance was evaluated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6‐dimethyldibenzothiophene (4,6‐DMDBT) at 613 K under 4 MPa as total pressure. In the HDS of DBT, NiW/Al2O3 exhibited better catalytic activity than NiW/HM and NiW/HM–M. On the contrary, NiW/HM–M exhibited the highest catalytic performance in the HDS of 4,6‐DMDBT, attributed to different factors: an improved dispersion of the active phase, a better accessibility to the active sites owing to the creation of mesoporosity, and an additional reaction route (isomerization) owing to the acidic properties of the zeolitic support. These results show the potential interest of hierarchical mordenite as support for HDS catalysts, with the presence of mesoporosity beneficial to the HDS of large and refractory molecules.

Application of HF etching in a HRTEM study of supported MoS2 catalysts

For the morphological study of the active MoS2 phase in supported hydrodesulfurization catalysts, the transmission electron microscopy (TEM) method suffers from contrast disturbance by the alumina support, and thus, top-view images of MoS2 slabs cannot be measured. HF etching was applied as an alumina-eliminating method for MoS2/Al2O3 catalysts and proved to be significant for TEM observation and statistical data processing of low-loading catalysts. High-resolution images of top-view MoS2 slabs were obtained after HF etching and MoS2 slabs were found to have different and irregular shapes. Vacancies at the edges of MoS2 slabs could be clearly detected. HF etching helped to identify that MoS2 slabs were preferentially basal-bonded on alumina independent of the precursors. When SBA-15 was used as support, basal-bonding dominated for catalyst with an oxidic precursor while edge-bonding for catalyst with a sulfidic precursor. Different MoS2 nanowires were observed after HF etching of MoS2/SBA-15 dependent on the precursors.

Garnierite: A new support for hydrodesulfurization catalysts

A Venezuelan garnierite sample from “Loma de Níquel” mine was treated with acid solutions of different concentrations. This method allowed an increase of BET surface area and a partial removal of Ni according to the acid concentration. The resulting solids were impregnated with Mo and their activity was tested in the thiophene hydrodesulfuration reaction. It was found that an increase of the surface area is positive for using garnierite sample in HDS reaction as long as the Ni removal was not excessive.

Synthesis of hydrothermally stable MCM-41 by the seed crystallization and its application as a catalyst support for hydrodesulfurization

MCM-41 is one of the weak hydrothermally stable members in M41s mesoporous silica family. Therefore, in the present work, an attention has been focused to improve its hydrothermal stability as well as to achieve more acidic sites on its surface structure, in order to make it a good candidate as a support for hydrodesulfurization (HDS) catalysts. Hydrothermally stable MCM-41 (MCM-41(HS)) has been successfully prepared by the seed crystallization method. The synthesized material was analyzed by the powder X-ray diffraction (XRD), nitrogen adsorption–desorption, ammonia-temperature programmed desorption (NH3-TPD), chemisorption of carbon monoxide (CO chemisorption), elemental analysis (EA) and solid NMR techniques. The characterization results showed that the hydrothermal stability of MCM-41(HS) was significantly improved due to presence of highly crosslinked framework walls, while the mesopore system remained highly ordered. The synthesized MCM-41(HS) has been initially used here as a support to prepare Mo/MCM-41(HS) catalyst for HDS application. The increased zeolitic phase in the wall of mesostructure is believed to increase the HDS activity of MCM-41(HS) supported Mo catalyst in contrast with conventional Al-MCM-41 supported Mo catalyst.

Preparation of supported hydrodesulfurization catalysts with enhanced performance using Mo-based inorganic–organic hybrid nanocrystals as a superior precursor

This article presents a novel strategy to prepare alumina-supported Mo and MoNi hydrodesulfurization (HDS) catalysts using Mo-based inorganic–organic hybrid nanocrystals (HNCs) as a superior precursor under moderate hydrothermal conditions. The characterization results revealed that each HNC in the aqueous solution has a size of ca. 2.5 nm and shows a core–shell structure with one Mo8O264− as the inorganic core and long-chain quaternary ammonium cations as the organic shell. The proposed approach not only significantly promotes the dispersion of supported Mo species, but also greatly enhances the stacking of MoS2 active phase, endowing the resulting catalysts with sufficient and accessible Ni–Mo–S active sites and thereby with a remarkably enhanced HDS performance as compared to their counterparts prepared by the conventional impregnation method. Thereby, a novel precursor for preparing Mo-based catalysts was successfully developed and the roles of the HNC-derived preparation method in tuning the size and morphology of supported metal sulfide nanoparticles in HDS catalysts were demonstrated, shedding a light on the rational design and controllable fabrication of supported metal sulfide catalysts.

Synthesis, characterization and catalytic performance of meso-microporous material Beta-SBA-15-supported NiMo catalysts for hydrodesulfurization of dibenzothiophene

Micro-mesoporous composite material Beta-SBA-15 (BS) with the Beta structure and SBA-15 mesoporous structure was synthesized and used as catalyst support for hydrodesulfurization (HDS) of dibenzothiophene (DBT). The supports and catalysts were characterized by various techniques including XRD, nitrogen adsorption, SEM, TEM, 27Al MAS NMR, and Pyridine-FTIR. The characterization results demonstrated that NiMo/BS had similar acidity to NiMo/Beta, and possessed more acid sites and stronger acidity than NiMo/SBA-15 and NiMo/Al 2O 3. Activity evaluation results showed that NiMo/BS exhibited the highest DBT HDS activity among all the catalysts that were studied, and the DBT conversion on NiMo/BS was about 1.6 times as much as that on NiMo/Al 2O 3 at weight time of 0.75 g min mol −1. The better catalytic performance of NiMo/BS was attributed to the superiorities of the pore structure and large amounts of acid sites of micro-mesoporous BS.

Bimodal mesoporous γ-Al2O3: A promising support for CoMo-based catalyst in hydrodesulfurization of 4,6-DMDBT

Bimodal mesoporous γ-Al2O3 (BMA) synthesized by a simple hydrothermal route was applied as support for CoMo-based catalyst. The materials were characterized and evaluated for hydrodesulfurization of 4,6-Dimethyldibenzothiophene (4,6-DMDBT) in a fixed-bed reactor. BMA displayed simultaneously high surface area, large porosity and particular hierarchically mesoporous structure after calcination at 550°C. By taking advantage of these properties, CoMo-BMA catalyst bearing high active species dispersion, good reducibility and enhanced diffusibility was used in this work to compare with commercial γ-Al2O3 supported catalyst. The obtained results showed that BMA had a good potential as support for hydrodesulfurization catalysts.

Ultra-deep hydrodesulfurization on MoS 2 and Co 0.1MoS 2: Intrinsic vs. environmental factors

A hydrogenation index (HI), measured in the hydrodesulfurization (HDS) of dibenzothiophene (DBT), is used to estimate the intrinsic hydrogenation selectivities of MoS 2, Co 0.1MoS 2, and two supported HDS catalysts. The HI and catalyst activity for desulfurizing 4,6-diethyl-DBT follow the same trend: MoS 2 ≫ Co 0.1MoS 2 ≫ supported catalysts. For desulfurizing a petroleum fraction rich in 4,6-alkyl-DBTs and 4-alkyl-DBTs, the activity decreases as follows: Co 0.1MoS 2 > supported catalysts ≫ MoS 2. These results introduce an apparent conundrum: MoS 2 has such a high hydrogenation power and activity for desulfurizing 4,6-diethyl-DBT, why does it perform poorly in real-feed tests? This conundrum is resolved by showing that an ultra-deep HDS catalyst requires an optimum balance between an intrinsic factor (hydrogenation function) and an environmental factor (tolerance of organonitrogen). Incorporating Co into MoS 2 lowers the hydrogenation function of MoS 2 and hence improves tolerance of organonitrogen. This conclusion corroborates the prediction of an early modeling study.

Synthesis and hydrodesulfurization performance of hierarchical mesopores alumina

In the presence of sucrose, hierarchical mesopores alumina was prepared and used as hydrodesulfurization catalyst support. The pore structure and acidic property of the alumina can be easily controlled by pH value and concentration of precipitator. The physical and chemical properties of catalysts are apparently changed when this novel structure alumina are introduced as support. The interaction between active component and support is decreased. The Mo species are facilely reduced and there are less acid sites on the surface of the catalysts. The unique properties make this catalysts possess higher conversion and desulfurizing ratio for 4,6-DMDBT in this study.

Advantages of ZrO 2- and TiO 2–SBA-15 mesostructured supports for hydrodesulfurization catalysts over pure TiO 2, ZrO 2 and SBA-15

In the present paper, we tried to illustrate the advantages that have ZrO 2- and TiO 2-containing mesoporous ordered SBA-15 materials in comparison with their pure oxide counterparts (SBA-15 silica, ZrO 2 and TiO 2) and γ-alumina when used as supports to prepare hydrodesulfurization (HDS) catalysts. To reach this aim, Mo catalysts supported on above materials were prepared and tested in dibenzothiophene HDS. The results show that Mo catalysts supported on TiO 2- and especially ZrO 2–SBA-15 are more active than all other samples including reference Mo/γ-Al 2O 3. To inquire into the reasons of this behavior, supports and catalysts were characterized by N 2 physisorption, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), isoelectric point (IEP), temperature-programmed reduction (TPR) and high resolution transmission electron microscopy (HRTEM).

Potential to use mesoporous carbon as catalyst support for hydrodesulfurization

Potential to use mesoporous carbon as catalyst support for hydrodesulfurization

Potential to use mesoporous carbon as catalyst support for hydrodesulfurization

A range of mesoporous carbons as potential supports to enhance ultra-deep hydrodesulphurization (HDS) of diesel fuel was synthesized using a sol-gel method. SBA-15 was used as template and sucrose and furfuryl alcohol were used as carbon sources. Various carbon incorporation approaches were used. From the results of nitrogen adsorption, transmission electron microscopy and X-ray diffraction, the synthesized carbon exhibited good replication of the SBA-15 structure. Loading of Co-Mo into the mesoporous carbons and catalysis dispersion were evaluated using various techniques including X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. The intrinsic HDS activity was evaluated by NO chemisorption on the prepared catalysts, which showed that the catalyst supported on mesoporous carbon using sucrose as carbon precursor has a higher NO uptake than that supported on commercial activated carbon.

Low-temperature synthesis of supported hydrodesulfurization catalysts based on chevrel phases

A new method has been developed for the synthesis of finely dispersed, highly active, supported hydrodesulfurization catalysts based on Chevrel phases. It is hypothesized that the modification of MoS2 with cobalt or nickel, which enhances the catalytic activity, and the same modification of Chevrel-type systems are of the same nature. The modifiers act through electron density donation into the conduction band of the active component. The increase in catalytic activity is due to the decrease of the effective charge of the molybdenum ion. The catalysts undergo partial restructuring during the reaction.

Characterization and Catalytic Activities of ZrO2-TiO2 Supported Hydrodesulfurization Catalysts

Pure ZrO2, TiO2, and ZiO2-TiO2 mixed oxides are prepared by urea hydrolysis. Hydrotreating catalysts containing 8 wt% (MoO3) and 3 wt% (NiO) are prepared using these oxides and characterized by the Brunauer, Emmett, and Teller (BET) surface area, pore volume, X-ray diffraction, Fourier transform infrared, differential thermal analysis, and scanning electron microscopy. Thiophene hydrodesulfurization, cyclohexene hydrogenation, and cumene hydrocracking are taken as model reactions for evaluating catalytic activities in a micro-catalytic reactor at 350°C and atmospheric pressure. Sulfided catalysts showed a wide range of activity variation as a function of support composition, which established that NiMo sulfided active phases strongly depend on the nature and composition of the support. It is found that catalytic activities increase with increasing zirconia content in mixed oxide and reach maximum values for 20% zirconia content. (20%) Zr/Ti mixed oxide supported catalyst was tested at high pressure with real gas oil feedstock. A thorough study of the relationship between operating conditions and product quality would contribute much to the optimization of hydrotreatment processes.