A series of granulated Ni/Al2O3 catalysts were prepared by impregnating the γ-alumina support with a nickel (II) ammine complex solution. The study of catalysts at different stages of preparation using IR and UV–Vis spectroscopy, XRD, thermogravimetric analysis, H2-TPR, TPD-CO2 and O2 chemosorption methods made it possible to trace the evolution of the active component. The interaction between the [Ni(NH3)5(H2O)]2+ cations and γ-Al2O3 results in the partial replacement of NH3 ligands with hydroxyl groups of the support, forming inner-sphere complexes between Ni2+ ions and the Al2O3 surface. Drying the catalyst at 140 °C causes the NH3 ligands in the nickel complexes to be replaced by H2O molecules and/or carbonate ligands. The calcination temperature of 300 °C is sufficient for decomposition of the active component precursor to NiO. In the calcined samples, almost all of the nickel oxide is strongly bound to the alumina surface. The highest reducibility was achieved for the samples calcined at 300 °C. Increasing the calcination temperature to 400 °C decreases the reduction rate. It was demonstrated that the reduction of oxide precursors (obtained by calcination at 300–400 °C) in an H2 flow at 400 °C leads to the formation of a highly dispersed nickel phase on the γ-Al2O3 surface. The Ni/Al2O3 catalysts synthesized using nickel ammine complexes show 40

Mg-Al mixed oxides (MgAlO, Mg:Al = 0.5, 2), gamma-Al2O3 and gamma-Al2O3, modified with Mg through impregnation (3 or 15 wt %) with supported Pt (1 wt %) showed principally different activity and stability in the reaction of nonoxidative methane coupling at 600 degrees C. In the most active Pt/Al2O3 and Pt/MgAlO samples under the reaction conditions, most of Pt was included into the reduced clusters (Pt/Al2O3 case) or their mixture with isolated reduced species and octahedral [Pt4+O x Cl y ]s (y -> 0) complexes (Pt/MgAlO case). Stabilization by possible bonding with Mg2+ in the MgAlO spinel lattice inhibited the irreversible Pt sintering, resulting in samples deactivation, and allowed a complete restoration of catalytic characteristics after burning out the carbonaceous deposits accumulated during the reaction. The Mg-Al solid solution formed in gamma-Al2O3-based samples could stabilize low-reactive Mg2PtO x Cl y -like compounds. The addition of 1.2 vol % H2 into 50 vol % CH4/N2 mixture substantially prolonged the period of stable formation of C2 reaction products due to the retardation of coke accumulation on the catalyst surface.

The study focuses on the effect of 1-70 wt % silica gel addition on the properties of CoMo/Al2O3 catalyst for fluid catalytic cracking gasoline hydrotreating. An increase in silica gel content results in an increase in the specific surface area and pore volume in the supports and catalysts. According to the IR spectroscopy of adsorbed CO and pyridine, the addition of any amounts of silica gel leads to the decrease in LAS concentration, while 30 wt % of silica gel leads to the formation of BAS typical for amorphous aluminosilicate. According to UV-vis spectroscopy and TPR-H-2, the dispersity of oxygen-containing compounds of active metals decreases when silica gel is added. The addition of 5-70 wt % of silica gel results in an increase in the average particle length of the active component from 2.1 to 2.2-2.7 nm and the stacking number from 1.8 to 1.9-2.2. Moreover, there is a correlation between Mo4+ content and catalyst's HDS activity. The catalyst with 30 wt % of silica gel had the highest Mo4+ content and the highest HDS activity. The formation of BAS in the catalysts with 30-70 wt % of silica gel leads to improved activity in isomerization of alkanes and alkenes, aromatization (or cyclization) of alkanes and alkenes, and alkylation of aromatics, and increased octane number of products from 89 to 92-93 points.

This paper presents a study on the effect of the Ni-Mo-W precursor calcination (300, 450 and 500 degrees C) on properties of granulated bulk Ni-Mo-W catalysts. The Ni-Mo-W precursor and bulk catalysts were studied by XRD, nitrogen adsorption-desorption method, CHNS analysis, thermal analysis, Raman spectroscopy, UV-Vis DR spectroscopy, HRTEM and XPS. It is shown that the increase in calcination temperature of the precursor to 500 degrees C leads to stepwise decomposition of citric acid, transformation of active metals and re-structurization of the samples. Active metals in sulfide catalysts are present in the bulk mixed or individual sulfides and interact with alumina binder to form "NiMoS-like" sulfide phase. Increased crystallinity of the precursor results in the enlargement of bulk nickel particles, capsulation of Mo and W and their rounding by Ni atoms. Catalysts testing in hydrotreatment of SRVGO demonstrates that the best choice of temperature regimes is 300 degrees C for the precursor.

Furfuryl alkyl ethers (FAEs) are considered attractive biofuels or gasoline additives. Reductive etherification of bio-based furfural (FF) is a promising method for production of these compounds. In present work, we study the catalytic behavior of Cu-Al mixed oxide in combination with HZSM-5-Al2O3 composites for the syntheses of FAEs in a flow reactor using H2 as a reducing agent. The Cu-based catalyst ensures the hydrogenation of FF to furfuryl alcohol, which then reacted with alcohol in the presence of the acid catalyst. It was found that the reaction of FF with 2-propanol over catalytic system including HZSM-5(Si/Al = 40)-Al2O3 leads to the formation of 2-(isopropoxymethyl)furan (IMF) in excellent yield due to the optimal concentration of strong Bronsted acid sites in the composite. Lower selectivity to IMF was observed in the presence of HZSM-5 with Si/Al ratio of 15, 25 and 140. In addition, the use of primary alcohols instead of 2-PrOH gives a significantly lower yield of FAEs.

BACKGROUND: One-stage hydroconversion of fatty-acid based feedstocks is a promising way to obtain high-quality fuels. This process is based on hydrodeoxygenation, isomerization and hydrocracking reactions. In this work, Ni2P/Al2O3-zeolite catalysts were synthesized and tested in hydroconversion of a model compound - methyl palmitate. RESULTS: Ni2P catalysts were prepared by in situ phosphidation of metallic Ni/Al2O3-zeolite precursors by PPh3. Mixtures of zeolite (30 wt%) and boehmite were peptized and extruded to obtain the support granules. SAPO-11, ZSM-5, ZSM-22, ZSM-23 and ZSM-12 were used as a zeolite component. The catalysts and supports were characterized by a range of physicochemical methods: chemical analysis (ICP-AES), low-temperature N-2 adsorption, H-2-temperature programmed reduction, NH3-temperature programmed desorption, Fourier transform infrared spectroscopy of adsorbed CO, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Al-27 and P-31 magic angle spinning nuclear magnetic resonance. The catalysts were studied in methyl palmitate hydroconversion (one-stage hydrodeoxygenation-isomerization-hydrocracking) in a continuous-flow fixed bed reactor at 290-340 degrees C, 2 MPa, H-2/feed = 600 Ncm(3)/cm(3) and LHSV = 5.3 h(-1). SAPO-11 containing sample showed high selectivity to C15 and C16 iso-alkanes (63%, at 340 degrees C), and all ZSM-containing samples showed high selectivity to cracked C5-C9 products (55-100%, at 340 degrees C) with varying amounts of iso-alkanes (31-57%, at 340 degrees C). CONCLUSION: The results show that by choosing the zeolite component of the catalyst it is possible to finely tune product quality in the range from low-temperature diesel fuel to jet fuel or gasoline. (c) 2024 Society of Chemical Industry (SCI).

A series of bifunctional catalysts, MoS2/Al2O3 (70 wt.%), zeolite (30 wt.%) (zeolite—ZSM-5, ZSM-12, and ZSM-22), and silica aluminophosphate SAPO-11, were synthesized for hydroconversion of methyl palmitate (10 wt.% in dodecane) in a trickle-bed reactor. Mo loading was about 7 wt.%. Catalysts and supports were characterized by different physical-chemical methods (HRTEM-EDX, SEM-EDX, XRD, N2 physisorption, and FTIR spectroscopy). Hydroprocessing was performed at a temperature of 250–350 °C, hydrogen pressure of 3.0–5.0 MPa, liquid hourly space velocity (LHSV) of 36 h−1, and an H2/feed ratio of 600 Nm3/m3. Complete conversion of oxygen-containing compounds was achieved at 310 °C in the presence of MoS2/Al2O3-zeolite catalysts; the selectivity for the conversion of methyl palmitate via the ‘direct’ hydrodeoxygenation (HDO) route was over 85%. The yield of iso-alkanes gradually increases in order: MoS2/Al2O3 < MoS2/Al2O3-ZSM-12 < MoS2/Al2O3-ZSM-5 < MoS2/Al2O3-SAPO-11 < MoS2/Al2O3-ZSM-22. The sample MoS2/Al2O3-ZSM-22 demonstrated the highest yield of iso-alkanes (40%). The hydroisomerization activity of the catalysts was in good correlation with the concentration of Brønsted acid sites in the synthesized supports.

Fluid catalytic cracking (FCC) gasolines are the most important components of blend gasolines. They are characterized by high octane number due to the great amount of olefins in their composition. However, one of the problems concerning FCC gasolines is the necessity of selective removal of diolefins, which can cause deactivation of catalysts for FCC gasoline hydrofining. In spite of the fact that NiMo/gamma-Al2O3 catalysts are usually used in the industrial process of selective diene hydrogenation, literature data on the influence of NiMo catalyst composition on the catalytic performance in selective diolefins hydrogenation are poorly covered. Therefore, the main goal of the present work was to clarify the aspects of the effect of NiMo/gamma-Al2O3 catalyst composition on their catalytic properties. The main feature of the catalysts was the higher Ni/Mo molar ratio (0.5 to 2) compared to those for the hydrotreating catalysts. The impregnating solutions, the support, and the catalysts were studied by nitrogen adsorption-desorption, attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, UV- vis diffuse reflectance spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectra. It was found that the increase in the Ni/Mo molar ratio from 0.5 to 2 resulted in the formation of the mixture of complex compounds like Ni-citrate, Mo-citrate, and NiMo-citrate complexes. It further influences the formation of the sulfide active component; especially, there is a decrease in the interaction of active metals with the support due to implementation of Ni to the support structure. It was found that the excess nickel in the catalysts also contributed to the greater promotion of MoS2 particles and the formation of bulk nickel sulfide particles. It was shown that the higher the Ni/Mo molar ratio, the higher the activity in selective isoprene hydrogenation, while selectivity did not depend on the molar ratio of active metals. The highest activity in isoprene hydrogenation was obtained for Ni/Mo molar ratio = 2.

Supported catalysts Al2O3/Cp2ZrX2 and Al2O3(F)/Cp2ZrX2 (X = Me, Cl) for the ethylene polymerization were synthesized by anchoring zirconocene on alumina and alumina, modified with 1–7 wt% fluorine (Al2O3(F)). The study revealed that Al2O3(F)/Cp2ZrMe2 catalysts are active in ethylene polymerization in the absence of organoaluminum cocatalyst, whereas Al2O3(F)/Cp2ZrCl2 catalysts are active in the presence of triisobutylaluminum as a co-catalyst. The metallocene complex was strongly anchored on the support. Active component leaching was not observed during polymerization. The acid–base properties of Al2O3(F) were studied by IR spectroscopy of adsorbed probe molecules: CO, pyridine and CDCl3. A maximum activity of the catalysts was observed in the case of the Al2O3(5%F) support, containing Lewis acid sites with absorption bands (νCO) at 2210–2215 cm−1, Brønsted acid sites with a proton affinity (PA) of 1190 kJ/mol, and weak basic sites with PA 850 and 795 kJ/mol. “Cationic-like” complexes formed on the Lewis acid sites with absorption bands at 2180−2200 cm−1 are inactive at ethylene polymerization.

The effect of support and different vanadia species present at different vanadium loadings on the catalytic performance of supported vanadia in the oxidation of formaldehyde to formic acid was examined. The catalysts with vanadium supported on SiO2, Al2O3, ZrO2, and TiO2 were prepared by impregnation. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy, and the temperature-programmed reduction technique. All catalysts and supports were tested in the oxidation of formaldehyde at 120 degrees C. It was found that activity in the oxidation of formaldehyde to formic acid is determined by the structure of vanadia species and the selectivity is determined by the coverage of support surface by these species. TiO2 (anatase) is the most suitable support for the formation of monolayer vanadium species which are the most active in the oxidation of formaldehyde to formic acid. (C) 2014 Elsevier B.V. All rights reserved.

Композиции на основе (Mn1 - xMx)О2 (М = Co, Pd), полученные в гидротермальных условиях и высушенные при 80°С, охарактеризованы методами РФА, ЭСДО, ЭМ, РФЭС, адсорбции и испытаны в реакции окисления СО в режиме ТПР СО + O2 и в изотермических условиях при комнатной температуре в отсутствие и в присутствии паров воды. Показано, что синтезированные образцы имеют туннельную структуру криптомелана независимо от природы и доли промотирующей добавки, их удельная поверхность составляет 110–120 м2/г. MnO2 однороден по морфологии, введение кобальта или палладия приводит к нарушению этой однородности и появлению более и менее окристаллизованных агрегатов различного размера. В композиции (Mn,Pd)O2 помимо оксидной фазы на основе MnO2 появляется контактирующий с ней металлический Pd, средний размер частиц которого не превышает 12 нм. Начальная активность образцов в реакции окисления СО, которую оценивали по температуре достижения 10%-ной конверсии СО, возрастает в ряду MnO2 (100°C) < (Mn,Co)O2 (98°C) < (Mn,Co,Pd)O2 (23°C) < (Mn,Pd)O2 (–12°C). Высокая активность (Mn,Pd)O2 обусловлена наличием на поверхности двух состояний палладия: окисленного (фаза взаимодействия) и металлического (кластеры Pd); последние диспергированы преимущественно в матрице MnO2. Этот катализатор эффективен в реакции окисления СО даже при комнатной температуре при отсутствии паров воды в реакционной смеси и не активен при их наличии. Показано, что присутствие паров воды приводит к частичному восстановлению ионов Mn4+ и увеличению доли металлических кластеров палладия.

IR spectroscopy Of two Supports was used for the determination of their Surface acidity. The presence of Lewis acid sites on the surface of sepiolite allowed the preparation of a catalyst able to transform citral into menthol in fairly good yield under very mild conditions (90 degrees C, 1 bar H-2).

IR spectroscopy has been used to study the interaction of silica with PhNEt2 (N) and B(C6F5)(3) (B) and subsequent interaction of the support SiO2/[N + B] with dimethylzirconocene Me2Si(2-Me-Ind)(2)ZrMe2 ("Zr"). The data were obtained on the composition of the surface compounds appeared at both stages of catalyst synthesis.It has been shown that (B) and (N) interact with OH groups of silica to form ionic pair [H-NR3](+)[(C6F5)(3)B-O-Sidrop](-) (IP-1). Cation fragment of this pair contains highly reactive N-H bond with a.b. at 3230 cm(-1). It has been found that N-H groups in a part of IP-1 complexes react with neighboring OH groups of silica by hydrogen bonding that gives complexes IP-2. It has been shown that "Zr" complexes interact both with complexes IP-1 and IP-2. As "Zr" reacts with IP-1, zirconium ionic complexes IP-3 containing Zr-Me bond are formed on silica. These complexes are suggested to be the precursor of the polymerization active sites. The reaction of "Zr" with IP-2, most likely, produces surface zirconium compound containing no Zr-Me bonds and inactive for propylene polymerization. (C) 2004 Elsevier B.V. All rights reserved.

The structure of solid methylalumoxane (MAO) and its behavior in the temperature interval from 20 to 250 degreesC have been studied using IR spectroscopy in diffusion reflection mode (DRIFT) and mass- spectrometric (MS) methods. It has been shown that three-dimensional MAO molecule may entrap water molecule in its volume (absorption bands (a.b.) 3550 cm(-1) in the IR-spectrum). Using a density functional theory (DFT) quantum-chemical method, the three-dimensional molecular model of MAO with composition (-Al(CH3)O-)(12), comprising water molecule in its structure, has been calculated. The release of the water molecule from the structure of MAO molecule is accompanied by the protolysis of Al-CH3 bonds and methane evolving. This reaction seems to be responsible for the observed evolving of methane on the MAO aging. As the temperature of MAO heating increases from 20 to 150 degreesC, the process of methane evolving intensifies.The heating of the solid MAO samples is also accompanied by the release of trimethylaluminum, (TMA) in significant amount (0.18 mole AlMe3/mole Al-MAO at 100 degreesC. Obviously, the released TMA was strongly associated with the MAO in the initial sample.The data on the activity in the ethylene polymerization of catalyst Cp2ZrCl2/MAO prepared with the use of the MAO samples dried at temperatures 20-250 degreesC are presented as well. (C) 2001 Elsevier Science B.V. All rights reserved.

Adsorption of NO as a probe molecule in infrared diffusion reflectance spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS) have been used in order to identify surface vanadium species in vanadium–magnesium catalysts (VMC). The presence of V3+ and V4+ in VCl4/MgCl2 and V4+ in VOCl3/MgCl2 was shown by XPS and DRIFTS. However, DRIFTS has some limitations due to oxidation of V3+ by the reaction with NO; moreover, apparently ions V5+ and V2+ do not adsorb NO. We have also demonstrated the possible identification of surface ions V5+ and V2+ in VMC using XPS. Practically in all cases (VCl2/MgCl2, VCl4/MgCl2 and VOCl3/MgCl2) one can see a mixture of vanadium ions in different oxidation and coordination states.

The surface organoaluminum compounds formed during repeated treatments of silica gel with triethylaluminum (TEA) and dioxygen (method A) and with TEA and water followed by heating in air and in a vacuum (method B) are studied by FTIR spectroscopy. The modification of silica gel using the methods A and B results in the formation of novel surface hydroxyl groups, which are characterized by absorption bands at 3615 and 3690 cm-l. According to the IR-spectroscopic data on CO adsorbed at low temperature, these OH groups are close in their acidity to OH groups of typical aluminosilicates. When using CO as a probe molecule adsorbed at room temperature and at the temperature of liquid nitrogen, the supports prepared by method A contain Lewis acid sites of two types: strong (2228 cm(-1)) and weak (2188 cm(-1)), and the supports prepared by method B also contain Lewis acid sites of a moderate strength (2210 cm(-1)). The concentrations of Lewis acid sites of various types are determined, and data on the influence of the modification procedure and the number of treatments on the concentrations of various Lewis acid sites are obtained.

The amorphous precursor method was used to prepare ferric molybdate catalysts containing superstoichiometric molybdate, sulfate, and phosphate ions. The introduction of sulfate or phosphate ions into stoichiometric ferric molybdate leads to the formation of double salts and the appearance of a proportional amount of molybdenum oxide, as indicated by IR spectroscopy and x-ray phase analysis. The dependence of the catalytic properties of these compounds derived from double salts on their composition is analogous to those characteristic for iron-molybdenum systems and the maximum activity is observed upon the introduction of these anions up to 2 mass % superstoichiometric composition. These results may be explained assuming that stoichiometric ferric molybdate is the active component in the iron-molybdenum catalyst, while double salts also with stoichiometric composition are the active component upon the introduction of sulfate and phosphate ions. A slight excess of molybdenum oxide is presumably necessary for maintaining the stoichiometry of the surface during catalyst preparation.