Catalysts For Hydroconversion Research Articles

Constructing a Pd-Co Interface to Tailor a d-Band Center for Highly Efficient Hydroconversion of Furfural over Cobalt Oxide-Supported Pd Catalysts.

Cobalt is an alternative catalyst for furfural hydrogenation but suffers from the strong binding of H and furan ring on the surface, resulting in low catalytic activity and chemoselectivity. Herein, by constructing a Pd-Co interface in cobalt oxide-supported Pd catalysts to tailor the d-band center of Co, the concerted effort of Pd and Co boosts the catalytic performance for the hydroconversion of furfural to cyclopentanone and cyclopentanol. The increased dispersion of Pd on acid etching Co3O4 promotes the reduction of Co3+ to Co0 by enhancing hydrogen spillover, favoring the creation of the Pd-Co interface. Both experimental and theoretical calculations demonstrate that the electron transfer from Pd to Co at the interface results in the downshift of the d-band center of Co atoms, accompanied by the destabilization of H and furan ring adsorption on the Co surface, respectively. The former improves the furfural hydrogenation with TOF on Co elevating from 0.20 to 0.62 s-1, and the latter facilitates the desorption of formed furfuryl alcohol from the Co surface for subsequently hydrogenative rearrangement of the furan ring to cyclopentanone on acid sites. The resultant Pd/Co3O4-6 catalyst delivers superior activity with a 99% furfural conversion and 85% overall selectivity toward cyclopentanone/cyclopentanol. We anticipate that such a concept of tailoring the d-band center of Co via interface engineering provides novel insight and feasible approach for the design of highly efficient catalysts for furfural hydroconversion and beyond.

Highly loaded copper-containing catalysts for hydroconversion of furfural

Highly loaded copper-containing catalysts synthesized by different methods (sol-gel, alloying and coprecipitation) were studied in hydroconversion of furfural in a batch reactor at a hydrogen pressure 5.0 MPA and temperature 100 °С. The reduction temperature and phase composition of the catalysts were determined using physicochemical methods. The highest activity in the process under consideration was observed for the coprecipitated copper-alumina catalyst, which at 100–130 °С allows obtaining furfuryl alcohol with 100 % selectivity; in addition, 2-methylfuran can be produced in the presence of this catalyst with the yield of 65 % at 200 °С. The phase composition of the catalyst reduced at a chosen temperature and the catalyst after the reaction was determined.

Constructing hierarchical structures of Pd catalysts to realize reaction pathway regulation of furfural hydroconversion

The technique of controlling nanoscale features precisely has been exploited to develop and improve bifunctional catalysts, which are important in the hydroconversion of furfural to high-value chemicals. Such bifunctional hydroconversion catalysts consist of metal sites and acid sites, and the intimacy extent of both active sites dictates the catalytic performance. In-depth exploration of the intimacy extent has been long limited by the lack of material synthesis and characterization method with nanometer precision. Herein, hierarchical catalytic structures with the spatial separation of Pd and acid sites were constructed by the multistep deposition strategy, wherein Pd was confined on defective CeO2 nanoclusters, which were dispersed on high-surface-area SiO2 with the strong acidity. The intimacy extent of Pd and acid sites in hierarchical catalytic structures of Pd/CeO2/SiO2 can be modulated by adjusting the CeO2 content, which leads to the aqueous-phase hydrogenation of furfural following a unique treble-site mechanism. The perpendicular adsorption of furfural on enriched oxygen vacancies of Pd/CeO2 contributes to the selective hydrogenation of the carbonyl group, and then the formed furfuryl alcohol undergoes the acid-catalyzed rearrangement of furan rings on SiO2 through the cooperative effect of acid sites and hydrogen spillover to give cyclopentanone. Meanwhile, the asynchronous catalysis effectively hinders the furan ring hydrogenation to tetrahydrofurfuryl alcohol by spatially separating Pd from the SiO2 surface. The superior catalytic performance is obtained on Pd/CeO2/SiO2-10 with a furfural conversion of 93% and cyclopentanone selectivity of 84%. We anticipate that the strategy of constructing hierarchical catalytic structures demonstrated here to spatially organize different active sites at the nanoscale will boost the further development of multifunctional catalysts.

Vanadium-Containing Heteropoly Acids of Keggin Structure as Precursors of CoPMoV Sulfide Catalysts for Hydroconversion of Dibenzothiophene and Naphthalene

Vanadium-Containing Heteropoly Acids of Keggin Structure as Precursors of CoPMoV Sulfide Catalysts for Hydroconversion of Dibenzothiophene and Naphthalene

Novel 3D-Printed Alumina Monolith Catalysts for Hydroconversion of Tar

This paper reports on a novel method for the preparation of monolith catalysts using a 3D-printed matrix. The development included an investigation into potential approaches to improving the strength of alumina catalysts, 3D printing of a polymer matrix (template) with a specific channel structure, preparation of templated monolith catalysts, an examination of their physicochemical properties, and testing of these catalysts in hydroconversion of tar. Using an indirect template method, this study is the first to prepare a Al2O3 monolith catalyst with a Schwartz surface microstructure. The extrudate drying rate was found to be the most important parameter for the synthesis of high-strength catalysts. The activity of the monolith catalyst proved to be comparable—and in some parameters even markedly superior—to that of similar granular samples. The tar hydroconversion product consisted of super heavy oil with 2.8 wt % of sulfur.

Nitrogen-doped porous carbon supported nickel nanoparticles as catalyst for catalytic hydroconversion of high-temperature coal tar

A novel and highly active nitrogen-doped porous carbon-supported nickel catalyst Ni@N-PC was successfully developed by a thermolysis of nickel-based zeolitic imidazolate frameworks growing on both sides of graphitic carbon nitride and used for catalyzing hydroconversion of isopropanol soluble portion from ultrasonic extraction of high-temperature coal tar (ISPHTCT). The active nickel nanoparticles were mainly encapsulated on the top of carbon nanotubes and partially dispersed on the surface of carbon nanosheets. Naphthalen-1-ol was used as a model compound to investigate the catalytic hydroconversion activity under different reaction conditions and reveal the mechanism for catalytic hydroconversion. The ISPHTCT and catalytic hydroconversion products of ISPHTCT (ISPCHCP) were analyzed with gas chromatograph/mass spectrometer. The results show that 70% of naphthalen-1-ol was converted at 160°C and completely converted at 200°C for 120 min, and the ISPHTCT was greatly upgraded. A total of 180 organic compounds including 33 nitrogen-containing organic compounds, 11 sulfur-containing organic compounds and 39 oxygenates were identified in ISPHTCT, while no obvious nitrogen-containing organic compounds, sulfur-containing organic compounds and oxygenates were detected in ISPCHCP, indicating the excellent performance of Ni@N-PC for heteroatom removal. All the alkenes, cyclenes and alkynes were saturated and the majority of arenes were converted to cyclanes by catalytic hydroconversion over Ni@N-PC, which exhibited high catalytic hydrogenation activity.

Hydroisomerization of n-hexadecane under mesoporous molecular sieve Pt/Al-SBA-15

1) Reduction of synthesis time of the Al-SBA-15 support. 2) The Pt/Al-SBA-15 catalyst was prepared by three different synthesis procedures. 3) Catalyst and support characterization by: XRPD, BET, NH3-TPD, SEM, TPR. 4) The Pt/Al-SBA-15 catalyst also presents low selectivity to cracked products. 5) The catalyst presented a 43% selectivity to the 7-methyl-pentadecane isomer. Oil derived products can be used effectively through the use of bifunctional catalysts in hydroconversion (hydroisomerization/hydrocracking) reactions. Therefore, the objective of this work was studying the n-hexadecane hydroisomerization using a bifunctional Pt/Al-SBA-15 catalyst, evaluating conversion and selectivity to mono branched products. The Al-SBA-15 support was synthesized by three different procedures, two described in literature, an innovator. The support was extensively characterized by several techniques. Pt was impregnated by incipient dry impregnation. The catalyst was characterized and activated. It was evaluated against the n-hexadecane isomerization in batch, 800 rpm, 280, 290 and 300 °C, and 55 bar, 0,052 grams of catalyst/ grams of reactant ratio. The conversion obtained was 100% for 30 h of reaction. The selectivity for mono-branched products obtained was 43% for all catalysts, remaining virtually constant with reaction time and temperature. Thus, this thorough work of bifunctional catalysts synthesis, characterization of the mesoporous support and application in hydroisomerization reactions, provides viable alternatives for the use of oil derived products in an efficient method.

Bifunctionality of a MoS2-Amorphous Silica–Alumina-Dispersed Catalyst for Slurry-Phase Hydroconversion: Effect of Acid and Hydrogenating Site Ratios

Bifunctionality of a MoS₂-Amorphous Silica–Alumina-Dispersed Catalyst for Slurry-Phase Hydroconversion: Effect of Acid and Hydrogenating Site Ratios

The mesoporous silicate-alumina composites application as supports for bifunctional sulfide catalysts for n-hexadecane hydroconversion

The mesoporous silicate-alumina composites application as supports for bifunctional sulfide catalysts for n-hexadecane hydroconversion

Impact of proximity between NiMoS and zeolitic HY sites on cyclohexene hydroconversion: An infrared operando study of sulfide catalysts

This work evaluates the effects of sulfide phase location on zeolite-containing catalysts in cyclohexene hydroconversion using the infrared operando technique. Parallels between activity, product yield, and surface species changes with time on stream and under pyridine poisoning were assessed on pure HY zeolite, sulfided NiMo/HY, NiMo/Al2O3, and NiMo/Al2O3 + HY. Isomerization activity could be related to zeolitic acidic OH groups and hydrogenation activity to sulfide phase sites. From the changes due to pyridine pulse injection, intrinsic activities could be calculated for isomerization (1-methyl-1-cyclopentene) and hydrogenation (cyclohexane) routes. The turnover frequency value for isomerization is greater than that for hydrogenation by one order of magnitude. Hence, the poisoning effect of one N-molecule on isomerization will be 10 times higher than that on the hydrogenation route. Whatever the location of the sulfide phase, the coke is mostly formed on the zeolite. As a consequence, on NiMo/HY, the close proximity between acidic and sulfide sites results in lower formation of hydrogenated products, due to blockage of some sulfide sites by coke. In contrast, the hydrogenation activity of NiMo/Al2O3 + HY is less affected by coke, NiMoS being mostly located on alumina. However, the results show that the close proximity between acid and sulfide sites allows a higher degree of hydrogenation of the isomerization product (1-methyl-1-cyclopentene). Thus, the higher proximity has a beneficial effect on methylcyclopentane formation.

Platinum catalysts supported on ZSM5 zeolites with a hierarchical pore structure: characterization and performance in n-hexadecane hydroconversion

HZSM5 zeolites with a hierarchical pore structure were prepared from a microporous one using the top-down methodology by treatment with a sodium hydroxide solution in optimal conditions of time, alkali concentration and temperature. These materials were used as supports for platinum to produce bifunctional hydroconversion catalysts. The activity in n-hexadecane hydroconversion was one order of magnitude larger on Pt supported on the mesoporous than on the untreated zeolite and one order of magnitude larger than that of the supports. All Pt catalysts and supports were more selective to hydrocracking than to hydroisomerization, but the initial selectivity for hydroisomerization of the Pt catalysts supported on the mesoporous supports was considerably smaller than that of all other materials, including the supports. This was attributed to a smaller mass transfer limitation with the Pt catalysts supported on the mesoporous zeolites. All supports and catalysts were extensively characterized by techniques such as X-ray diffraction, hydrogen chemisorption, TPD of ammonia, IR spectroscopy of adsorbed pyridine, MAS 29Si and 27Al solid state NMR and transmission electron microscopy.

Insights in supported rhenium carbide catalysts for hydroconversion of lignin-derived compounds

Rhenium supported over activated carbon (AC) was carburized under different temperatures (from 500 to 700 °C) under a mixture of H2/C2H4 (75/25). Resulting catalysts were characterized by N2-sorption, CO chemisorption, temperature programed reduction (TPR), ammonia temperature programed desorption (TPD-NH3), STEM, and XPS and catalytic properties were measured in a batch reactor at 350 °C, 5.0 MPa for the hydrodeoxygenation (HDO) of guaiacol. Results have shown that Rhenium was gradually reduced and carburized upon increasing the temperature. From 650 °C, a RexC phase was obtained and transformed into ReC at 700 °C. RexC was the most active phase obtained and maximum yield in benzene of 51% was reached at complete conversion. ReC phase showed to inhibit the hydrogenolysis of phenol into benzene.

TEOS-modified Ni/ZSM-5 nanosheet catalysts for hydroconversion of oleic acid to high-performance aviation fuel: Effect of acid spatial distribution

Abstract Ni/ZSM-5 nanosheet catalysts with different Si/Al ratios were modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) to tailor their acid spatial distribution. Their catalytic performance was evaluated with the hydroconversion of oleic acid to aviation-fuel-range-alkanes (AFRAs) at different reaction temperatures and H2 pressures. The modified catalysts inherit the nanosheet structure with decreased external Bronsted acid concentration, especially the strong one. External Bronsted acid sites mainly favor the cracking of the deoxygenated products (C17/C18). Internal Bronsted acid sites mainly enhance the isomerization of the linear AFRAs. And the catalytic activity of the external Bronsted acid sites was more sensitive to reaction temperature than that of the internal ones. The deoxygenation and cracking reactions were also more sensitive to H2 pressure compared to the isomerization reaction. High AFRA selectivity of 51.4% as well as high iso/n-alkanes ratio of 1.7 were achieved at 250 °C and 10 bar over NS200(1).

Hydroconversion of Aromatic Hydrocarbons over Bimetallic Catalysts

Bimetallic catalysts (BMC) for hydroconversion of aromatic hydrocarbons (ArH) have been designed by modification of Ni/Al2O3 with chromium(0) compounds and phosphoromolybdic heteropolyacid (HPA). Catalysts were tested in hydrogenation of benzene and toluene, in hydrodemethylation of pure toluene and they were shown to possess a high activity, selectivity and sulfur tolerance under conditions of the processes above. The activity of BMC in these processes was much higher as compared with that of two-component (Ni-Cr, Ni-HPA) or conventional Ni/Al2O3 catalysts. Using BMC, hydrogenation of benzene and toluene proceeds with activity increased (up to 34–38 mol/kg·h) and toluene hydrodemethylation may be performed with improved selectivity (90.3%) and benzene yield (81%). The high sulfur tolerance of BMC was demonstrated by performing hydrodemethylation of toluene containing up to 500 ppm S.

The Properties of Water-in-Oil Emulsions of Aqueous Solutions of Precursors for Nanosized Catalysts

The preparation of water-in-oil (w/o) emulsions on the basis of aqueous solutions of precursors for catalysts of hydrocarbon hydroconversion is a key stage of the production of nanosized dispersions of catalyst particles. The paper presents the results of a study of the regularities for the formation of w/o emulsions of aqueous solutions of the following precursors for hydroconversion catalysts: (NH4)6Mo7O24, (NH4)2WO4, Fe(NO3)3, and Ni(NO3)2. The effects of the aqueous phase composition and the presence of nonionic surfactants on the properties of the w/o emulsions have been determined. It has been shown that native surface-active components of oil products are highly efficient stabilizers of emulsions containing precursors for hydroconversion catalysts.

Effect of Additives on the Activity of Nickel–Tungsten Sulfide Hydroconversion Catalysts Prepared In Situ from Oil-Soluble Precursors

The nickel–tungsten sulfide catalysts for the hydroconversion of hydrocarbons were prepared from oil-soluble nickel and tungsten precursor compounds in situ with the use of silica, alumina, titania, zeolite Y, and amorphous aluminosilicate as additives in a vacuum gas oil medium. It was found that the catalytic activity in hydrocracking depends on the concentration of acid sites in the resulting catalyst. With the use of oxide additives, the dispersion and the promoter ratio of the in situ formed sulfide particles increased in the order SiO2–Al2O3–TiO2. It was noted that the promoter ratio of sulfide particles obtained with the use of aluminosilicate additives depended on their porous structure peculiarities. The use of titanium dioxide as a catalytic system component made it possible to reach high activity in hydrocracking, hydrodearomatization, and hydrodesulfurization, which was comparable to that of a system based on zeolite Y, a highly acidic component.

Mechanochemical Synthesis of Fine Carbide-Containing Catalysts for Hydroconversion of Heavy Oil Residues

Mechanochemical Synthesis of Fine Carbide-Containing Catalysts for Hydroconversion of Heavy Oil Residues

Mesoporous Al-HMS and Al-MCM-41 supported Ni-Mo sulfide catalysts for HYD and HDS via in situ hydrogen generation through a WGSR

The mesoporous aluminosilicates Al-HMS (Si/Al = 10) and Al-MCM-41 (Si/Al = 20) types were synthesized via the neutral templating pathway and used as supports for Ni-Mo sulfide catalysts, prepared by standard incipient wetness co-impregnation technique followed by sulfidation procedure. Ni and Mo content were 7 and 24 wt.% respectively. Both mesoporous aluminosilicates and supported oxide Ni-Mo catalyst precursors were characterized by TEM, solid-state 29Si and 27Al MAS NMR, N2 adsorption/desorption, TPD-NH3, TPR-H2, ICP-AES techniques. The chemical state and surface composition of freshly sulfided catalysts were revealed by XPS and TEM. The performance of mesoporous Al-HMS and Al-MCM-41 supported Ni-Mo sulfide catalysts in hydroconversion of 1-methylnaphtalene (1 MN), 2- methylnaphthalene (2 MN) and dibenzothiophene (DBT) was studied in high-pressure batch reactor at T = 320-400 °C, P(CO) = 3–5 MPa in the presence of water (20 wt.%) providing in situ hydrogen generation through a water gas shift reaction (WGSR). The results obtained showed that Al-HMS-based catalysts are more active in hydrogenation of aromatics while the higher DBT conversions were obtained over Al-MCM-41 supported catalyst. Mo-containing supported catalysts promoted by Ni were found the most active at T = 380 °C, P(CO) = 3 MPa and CO/H2O molar ratio 1.5–2.0.

Bifunctional MoS2-Silica-Alumina Catalysts for Slurry Phase Phenanthrene-Decalin Hydroconversion

MoS2-amorphous silica-alumina (MoS2-ASA) bifunctional catalysts for slurry-phase hydroconversion of the model reactants phenanthrene and decalin were prepared using three distinct methodologies. The MoS2-ASA catalysts were prepared by (i) a mechanical mixture of MoS2 (prepared separately) and ASA, which were mixed directly in the reactor for the hydroconversion test (MM catalyst); (ii) in situ sulfidation of the molybdenum precursor in the presence of the ASA, both dispersed in the phenanthrene-decalin reaction mixture (IS catalysts); and (iii) impregnation of molybdenum octoate onto ASA, followed by thermal treatment to chemically link the Mo precursor to the ASA surface followed by sulfidation prior to the catalytic test (IMP catalyst). Among the three preparation methods, the MoS2-ASA catalysts prepared in situ (IS) had the highest MoS2 dispersion and degree of sulfidation and yielded the highest hydrogenating activity at the lowest Mo catalyst content (2.9Mo-ASA). Although the MoS2 blocked Bronsted ac...

Incorporation of Ni and Mo on delaminated clay by auto-combustion and impregnation for obtaining decane hydroconversion catalysts

A series of solids was synthesized by the incorporation of Ni and Mo active species on delaminated clay with novel acidic properties, by impregnation and auto-combustion. The resulting solids were characterized by X-ray fluorescence, X-ray diffraction (XRD), textural analysis by N2 physisorption, temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and, in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). Decane hydroconversion was used to evaluate the potential of the materials as hydrocracking catalysts for vacuum bottoms. XRD was used to confirm modification of the material and good active phase dispersion. TPR revealed an important decrease in the reduction temperatures with auto-combustion method. Low-temperature reducible species play a key role in the catalytic performance for decane hydroconversion.