Hydroprocessing Catalysts Research Articles

Novel catalysts for advanced hydroprocessing: transition metal phosphides

The field of catalysis is continuously invigorated by the discovery of new catalytic materials. Transition metal phosphides represent one such group of compounds that have recently been shown to have excellent activity for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN). This is an important area, as continuous decline in the quality of petroleum feedstocks and increasingly stringent environmental regulations have made the removal of sulfur a paramount problem in the refining industry. The structure of the metal-rich phosphides is based on trigonal prisms, which can well accommodate the relatively large phosphorus atoms. The prisms are similar to those in sulfides, but phosphides do not take on layered structures and are metal conductors, not insulators or semiconductors. Lack of layers leads to a more isotropic crystal morphology and potentially better exposure of surface metal atoms to fluid phase reactants. Phosphides can be prepared readily in bulk and supported forms by reduction of phosphate precursors. The catalytic activity of the phosphides for dibenzothiophene HDS and quinoline HDN at 643 K and 3.1 MPa followed the order Fe2P<CoP<MoP<WP<Ni2P. The best catalyst, Ni2P/SiO2, had better activity in hydroprocessing than a commercial Ni–Mo–S/Al2O3 (HDS 98% vs 78% and HDN 80% vs 43%), based on equal sites loaded in the reactor. The sites were titrated by CO chemisorption at room temperature for the phosphides and by pulse O2 chemisorption at dry-ice acetone temperatures for the sulfide. The Ni2P/SiO2 also compared favorably with a commercial Co–Mo–S/Al2O3 catalyst (Ketjenfine 756) using a real feed at 593 K and 3.9 MPa. On the basis of equal weights loaded in the reactor, the Ni2P was again found to have higher performance than the sulfide (HDS 85% vs 80%). Studies of Ni2P/SiO2 catalysts with varying Ni/P ratios indicated that the principal phase remained Ni2P, but that the crystallite size decreased with increasing P content as a result of facilitated contact on the surface between the Ni component and the phosphorus reagent. Activity measurements on these samples indicated that HDS was structure-insensitive, but that HDN was structure-sensitive. Extended X-ray absorption fine structure measurements indicated that the surface formed a phospho sulfide after reaction. The mechanism of HDN was investigated using a series of molecular probes of varying structure. The reactivity order for pentylamines indicated that CNH2 bond scission proceeded by a β-hydride elimination mechanism, similar to that occurring on sulfides. The reactivity order of substituted piperidines indicated that ring-opening proceeded by CN bond scission and involved an α-carbon, and thus was different from the pathway on sulfides, which again appeared to involve a β-hydride elimination. This difference may account for the higher activity of phosphides over sulfides.

Characterization of Silica-Supported Molybdenum and Tungsten Phosphide Hydroprocessing Catalysts by 31P Nuclear Magnetic Resonance Spectroscopy

Silica-supported molybdenum phosphide, MoP/SiO2, and tungsten phosphide, WP/SiO2, were prepared and characterized for their catalytic activity in hydrodenitrogenation (HDN) and hydrodesulfurization (HDS). The silica-supported phosphides were tested in the simultaneous hydroprocessing of quinoline and dibenzothiophene at 3.1 MPa and 643 K and were compared to a MoS2/SiO2 sample. The supported phosphides had superior HDN and lower HDS activity compared to the sulfide under these conditions. The conversion levels of MoP/SiO2 were similar to those of bulk MoP, while the WP/SiO2 was somewhat less active than its bulk WP counterpart. However, when compared on a CO uptake basis, the bulk materials had a clear performance advantage. Solid state nuclear magnetic resonance measurements indicated 31P shifts from 85% H3PO4 of 255 ppm for WP and 214 ppm for MoP. Comparison of freshly prepared and passivated samples indicated that the supported phosphides were susceptible to surface oxidation on exposure to the atmosphere as a result of their small particle size.

Synthesis and Activity of a New Catalyst for Hydroprocessing: Tungsten Phosphide

A tungsten phosphide, WP, hydrotreating catalyst was prepared by temperature-programmed reduction of an X-ray amorphous tungsten phosphate at a heating rate of 0.0167 K s−1 and a 2-h soak at the final temperature of 938 K. Characterization of intermediates quenched at different temperatures revealed a single crystalline reaction product whose specific CO uptake and BET surface areas passed through a maximum of 12 μmol g−1 and 15 m2 g−1, respectively, at 873 K. Heating rate variation measurements gave an apparent first-order activation energy of 148 kJ mol−1 for the reduction. Tungsten phosphide was catalytically active in the hydrodenitrogenation and hydrodesulfurization reactions of a simulated light oil consisting of 20 wt% tetralin, 76 wt% tetradecane, 2000 wppm N as quinoline, 3000 wppm S as dibenzothiophene, and 500 wppm O as benzofuran. Measurements were made in an upflow fixed-bed reactor operated at 3.1 MPa and 643 K and gave conversion levels at steady state for the WP catalyst of 58% HDN and 67% HDS. These conversions were superior to those found for WC, W2N, and WS2 tested under the same conditions.

Coke and minerals removal from bitumen hydroconversion catalysts

Hydroconversion of bitumen is an important technology for cracking the residue fraction, but the use of catalysts in ebullated beds suffers from high catalyst consumption. The catalyst pellets accumulate coke, vanadium and nickel sulfides and an external skin of calcium and iron minerals. Spent hydroprocessing catalysts from conversion of Athabasca bitumen were extracted with a hydrotreated gas oil and heteroatomic solvents in order to remove coke and rejuvenate catalyst activity. The extraction conditions ranged from 25 to 430°C and times from 1 to 24h. The gas oil was a good solvent for removing coke that had been deposited on fresh catalyst for only a few hours, but it was not effective for the removal of aged coke from catalyst from an industrial reactor. Heteroatomic solvents such as quinoline tended to deposit or adsorb on the catalyst, rather than extract the coke material. The optimal conditions for coke removal were at temperatures below 400°C and under a hydrogen atmosphere.Two methods were used to remove the skin of mineral deposits from the commercial spent catalyst: abrading the surface with aluminum oxide and washing with dilute acid. Grinding off the mineral skin had little effect on the hydrodesulfurization activity of catalysts, while acid washing was able to recover part of activity of the spent catalysts.

A new method for preparing highly active unsupported Mo sulfide. Catalytic activity for hydrogenolysis of 4-(1-naphthylmethyl)bibenzyl

This paper reports on the catalytic activity of unsupported Mo sulfide (MoS 2 like) catalysts which were prepared by a new and simple method comprised of decomposing ammonium tetrathiomolybdate (ATTM) in an organic solvent with added water under H 2 pressure. Model compound reactions of 4-(1-naphthylmethyl)bibenzyl (NMBB) were carried out at 350–425°C under H 2 pressure in order to examine the activity of the Mo sulfide catalysts generated from ATTM with and without added water for C–C bond cleavage and hydrogenation of aromatic ring. The Mo sulfide catalysts generated from ATTM with added water were much more effective for C–C bond cleavage and hydrogenation of aromatic moieties at 350–425°C than those from ATTM alone. Two-step tests revealed that the addition of water is effective for generating highly active Mo sulfide catalyst from ATTM, but water itself does not promote catalytic conversion. Removal of water after the decomposition of ATTM with added water at 350–400°C under H 2 pressure by hot purging gives highly active Mo sulfide catalyst. These results demonstrate that we have found a new and simple method for preparing highly active, dispersed (unsupported) Mo sulfide catalysts for hydroprocessing.

New Catalysts for Hydroprocessing: Bimetallic Oxynitrides MI–MII–O–N (MI, MII=Mo, W, V, Nb, Cr, Mn, and Co): Part I. Synthesis and Characterization

A new family of bimetallic oxynitride compounds, MI–MII–O–N (MI, MII=Mo, W, V, Nb, Cr, Mn, and Co), has been synthesized by nitriding bimetallic oxide precursors with ammonia gas via a temperature programmed reaction. The oxide precursors are prepared by conventional solid state reaction between two appropriate monometallic oxides. The synthesis involves passing NH3gas over the oxide precursors at a flow rate of 6.80×102μmol s−1(1000 cm3/min) and raising the temperature at a heating rate of 8.3×10−2K s−1(5 K/min) to a final temperature (Tf) which is held constant for a short period of time (thold). The oxynitrides thus obtained are pyrophoric and need to be passivated before exposing them to air. All these new bimetallic oxynitrides have a face centered cubic crystal structure and high values of surface area. The surface reactivation and the thermal stability of the materials are studied by temperature programmed reduction and this indicates that the compounds can be divided into three groups of different reducibility (high, medium, and low). Their surface activity and surface area are evaluated based on CO chemisorption and N2physisorption measurements. It is found that the chemisorbed CO number density correlates with the reducibility of the compounds.

Recent trends of industrial catalysts for resid hydroprocessing in Japan

To meet the gradual changes in petroleum demand, in particular a reduced demand for heavy fuel oil, advanced technology for resid hydroprocessing is now extremely necessary. The catalyst technology for resid hydroprocessing in Japan, especially fixed bed type of hydrodesulfurization and hydroconversion, is reviewed in this article.

97/02688 Activity of noble metal-promoted hydroprocessing catalysts for pyridine HDN and naphthalene hydrogenation

97/02688 Activity of noble metal-promoted hydroprocessing catalysts for pyridine HDN and naphthalene hydrogenation

Hydrodemetallisation of residual oil with catalysts using fibrillar alumina as carrier material

Hydroprocessing catalysts were prepared using fibrillar aluminas as carrier materials and sulphides of nickel and molybdenum as active substances. The fibrillar aluminas were obtained from fibrillar boehmite samples prepared at three different synthesis conditions resulting in different fibril sizes. After extrudation and deposition of metals, catalysts combining large surface areas with large average pore diameters were obtained. The catalysts were tested for hydrodemetallisation of an atmospheric residue and the results were compared with those obtained for a commercial reference catalyst with a similar loading of nickel and molybdenum. Two of the catalysts prepared using fibrillar alumina as carrier material were more active than the commercial catalyst. The third catalyst containing the largest alumina fibrils was inferior to the other catalysts in all respects. Catalyst deactivation was investigated in a long-term hydroprocessing experiment using a heavy vacuum residue containing large amounts of metals as a feed oil. The catalyst prepared using fibrillar alumina used in this test showed a constant level of hydrodemetallisation even after 500 h on stream whereas the reference catalyst was completely deactivated after 350 h.

Simultaneous Determination of Oil and Coke Contents in Spent Hydroprocessing Catalyst by Thermogravimetry

Spent alumina-based nickel−molybdenum catalysts used for hydroconversion of heavy oil or residuum upgrading are subjected to thermogravimetric analysis (TGA) to determine oil and coke contents simultaneously. TGA or differential TGA curves clearly indicate that oil and carbonaceous materials are driven off at 100−300 °C and 300−700 °C ranges, respectively. The amounts of oil, coke, and inorganic residue obtained by the single-step TGA procedure are found to be in excellent agreement with those obtained by conventional methods such as Soxhlet extraction for the oil content followed by calcining of the deoiled catalyst in a muffle furnace for the coke and inorganic residue contents. Since the TGA results at heating rates of 10, 20, and 30 °C/min are found to be statistically invariant, the analysis time can be as short as 26 min, which is advantageous for monitoring and control of catalyst performance in an operating unit.

Activity of noble metal-promoted hydroprocessing catalysts for pyridine HDN and naphthalene hydrogenation

An important step in the upgrading of coal and coal-waste coprocessing liquids is the removal of heteroatoms, particularly nitrogen, which tend to poison the downstream cracking operations required to lower boiling points to the transportation fuels range. This requirement has motivated research to improve the activity of current hydroprocessing catalysts. In this regard we have examined the effects of Pt, Ru, and Ir promotion on three commercial Al 2O 3-supported catalysts (NiMo, CoMo, and NiW) using the model compounds, pyridine and naphthalene, to investigate hydrodenitrogenation and ring hydrogenation reactions, respectively. For pyridine hydrodenitrogenation (HDN), the activity of the sulfided catalysts was better than that of the oxide forms. For sulfided forms of NiMo, all noble metals tested improved the HDN activity. The activity of CoMo was improved by Pt and Ir while NiW was not improved by any noble metals promotion. For ring hydrogenation (HYD) of naphthalene, the Pt-promoted catalysts were more active than the original catalysts in the oxide forms, while the activities of both catalysts were similar after sulfidation. However for ring HYD in the presence of N, the Pt-promoted catalysts exhibited a distinct advantage.

96/01327 Nickel-containing catalysts for hydroprocessing of aromatic oils

96/01327 Nickel-containing catalysts for hydroprocessing of aromatic oils

Nickel-containing catalysts for hydroprocessing of aromatic oils

A series of nickel-containing catalysts was prepared by a sequence of impregnation and calcining steps using a γ-alumina support. The calcined catalysts were reduced in a flow of hydrogen and mixtures of hydrogen with hydrogen sulfide. Both the calcining temperature and nickel loading strongly influenced the hydrogenation activity. The changes in surface species which resulted from some of the preparation steps were identified by spectroscopy. The catalysts containing nickel without molybdenum were quickly poisoned by sulfur, but a certa in sulfur tolerance was achieved by a two-step impregnation and calcining procedure. Improved hydrogenation activity and high hydrogenation vs. hydrocracking selectivity of nickel—molybdenum catalysts were obtained with relatively low loading of molybdenum and high loading of nickel. A three-step impregnation and calcining procedure appeared to produce the most effective catalysts.

Nickel-containing catalysts for hydroprocessing of aromatic oils

Nickel-containing catalysts for hydroprocessing of aromatic oils

New Catalysts for Hydroprocessing: Transition Metal Carbides and Nitrides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Catalysts for Hydroprocessing: Transition Metal Carbides and NitridesS. Ramanathan and S. T. OyamaCite this: J. Phys. Chem. 1995, 99, 44, 16365–16372Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://doi.org/10.1021/j100044a025RIGHTS & PERMISSIONSArticle Views2690Altmetric-Citations289LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (785 KB) Get e-Alerts

95/03410 Process of change

Ruthenium sulphide catalysed hydrodenitrogenation (HDN) of quinoline and hydrodesulphurization (HDS) of benzothiophene were studied using a batch autoclave (cold filled with 3448 kPa of hydrogen), at 350400 °C and 300350 °C, respectively. Ruthenium from various precursors—[Ru Cl3xH2O], [Ru3(CO)12], [Ru(NH3)6]3+—was supported on Y-zeolite and γ-Al2O3, and then sulphided. The catalysts were highly active for HDN but not for HDS by comparison with a conventional NiMoAl2O3 formulation. The results were attained with metal loadings (~5%) much lower than those used in conventional hydroprocessing catalysts. Physical combination of the most active catalyst, ruthenium sulphide supported on Y-zeolite, with sulphided nickel molybdate on alumina resulted in a catalyst system with greatly enhanced activity for HDN.

Large-Pore Catalysts for Hydroprocessing of Residual Oils

Hydroprocessing catalysts were prepared using fibrillar alumina and attapulgite as carrier materials and nickel and molybdenum as active substances. With fibrillar alumina as primary particles, a carrier material was obtained which combined a large surface area (138 m{sup 2}/g) with a large average pore diameter (252 {angstrom}). Due to side-by-side association of the fibers, attapulgite did not yield a catalyst carrier with as large pores as was expected. The catalysts were tested for hydroprocessing of an atmospheric petroleum resid, and the results were compared with those obtained for a commercial catalyst with similar loading of nickel and molybdenum. The catalyst prepared using fibrillar alumina as carrier material was more active than the commercial catalyst for hydrodemetallization, equally active for hydrodesulfurization, and less active for hydrodenitrogenation. The catalyst prepared using attapulgite as carrier material was inferior to the other two catalysts in all respects.

Hydrogen mobility of coal and solvent under coal liquefaction conditions — Estimation of hydrogen transfer using tritium tracer methods

Ruthenium sulphide catalysed hydrodenitrogenation (HDN) of quinoline and hydrodesulphurization (HDS) of benzothiophene were studied using a batch autoclave (cold filled with 3448 kPa of hydrogen), at 350400 °C and 300350 °C, respectively. Ruthenium from various precursors—[Ru Cl3xH2O], [Ru3(CO)12], [Ru(NH3)6]3+—was supported on Y-zeolite and γ-Al2O3, and then sulphided. The catalysts were highly active for HDN but not for HDS by comparison with a conventional NiMoAl2O3 formulation. The results were attained with metal loadings (~5%) much lower than those used in conventional hydroprocessing catalysts. Physical combination of the most active catalyst, ruthenium sulphide supported on Y-zeolite, with sulphided nickel molybdate on alumina resulted in a catalyst system with greatly enhanced activity for HDN.

Characterization of Coke on Spent Hydroprocessing Catalysts by Optical Microscopy

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of Coke on Spent Hydroprocessing Catalysts by Optical MicroscopyVincente A. Munoz, Suhas V. Ghorpadkar, and Murray R. GrayCite this: Energy Fuels 1994, 8, 2, 426–434Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://doi.org/10.1021/ef00044a022RIGHTS & PERMISSIONSArticle Views146Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (4 MB) Get e-Alerts Get e-Alerts

A Ca-modified NiMo catalyst for hydroprocessing of coal liquid bottoms in two-stage coal liquefaction

Hydroprocessing of de-ashed coal liquid bottoms (DAO) derived from Victorian brown coal liquefaction was carried out in a fixed-bed reactor loaded with molybdenum catalyst. The conventional hydroprocessing catalyst is deactivated by the preasphaltene contained in the coal liquid bottoms. This deactivation is believed to be due to the fact that nitrogen compounds are strongly adsorbed on the acid sites, and converted into coke-like products by poly-condensation and dehydrogenation. They then cover the hydrogenation sites, which are active sites for DAO conversion to oil. The catalyst CaONiOMoO 3/ Al 2O 3, investigated on the basis of this hypothesis, showed stable activity for a long time and was active for DAO with a high concentration of preasphaltene. Coke analysis of the used catalyst showed that Ca modified catalyst had a lower deposition of coke-like products and a lower nitrogen concentration in the deposit, supporting the hypothesis.