A. S. Noskov

Comparative XPS Study of Al2O3 and CeO2Sulfation in Reactions with SO2, SO2 + O2, SO2 + H2O, and SO2 + O2 + H2O

The interactions of Al2O3, CeO2, Pt/Al2O3, and Pt/CeO2 films with SO2, SO2 + H2O, SO2 + O2, and SO2 + O2 + H2O in the temperature range 300–673 K at the partial pressures of SO2, O2, and H2O equal to 1.5 × 102, 1.5 × 102, and 3 × 102 Pa, respectively, were studied using X-ray photoelectron spectroscopy. The formation of surface sulfite at T ≥ 473 K (the S 2p3/2 binding energy (Eb) is 167.5 eV) and surface sulfate at T   ≥  573 K (Eb = 169.2 eV) was observed in the reactions of Al2O3 and CeO2 with SO2. The formation of sulfates on the surface of CeO2 occurred much more effectively than in the case of Al2O3, and it was accompanied by the reduction of Ce(IV) to Ce(III). The formation of aluminum and cerium sulfates and sulfites on model Pt/Al2O3 and Pt/CeO2 catalysts occurred simultaneously with the formation of surface platinum sulfides (Eb of S 2p3/2 is 162.2 eV). The effects of oxygen and water vapor on the nature and yield of sulfur-containing products were studied.

Hydrocracking of vacuum gas oil in the presence of supported nickel-tungsten catalysts

The supports containing 70% Al2O3 and 30% β zeolite (AZ-1 and AZ-2), which differed in mixing procedures, and the Ni-W/AZ-1 and Ni-W/AZ-2 catalysts were characterized using an adsorption technique, high-resolution electron microscopy, IR spectroscopy, and X-ray photoelectron spectroscopy and tested in the hydrocracking reaction of vacuum gas oil (VGO). It was found that the supports differed in texture characteristics and surface Lewis acidity at the same composition and similar concentrations of Brønsted acid sites. The formation of Ni-W-S sulfide species on the surfaces of both of the supports occurred in different manners: multilayer Ni-W-S sulfide species were formed on AZ-1 (Ssp = 220 m2/g), whereas single-layer species were mainly formed on AZ-2 (Ssp = 380 m2/g). It was found that catalysts containing multilayer Ni-W-S sulfide species, which were characterized by a higher degree of sulfidation, provided a higher yield of diesel fuel upon the hydrocracking of VGO, whereas catalysts containing single-layer Ni-W-S sulfide species were more active in the reactions of VGO hydrodesulfurization and hydrodenitration.

Influence of the heat treatment conditions on the activity of the CoMo/Al2O3 catalyst for deep hydrodesulfurization of diesel fractions

The effect of the heat treatment temperature on the sulfidation and activity of CoMo/Al2O3 catalysts designed for deep hydrodesulfurization of diesel fuel was studied. The catalysts were prepared using citric acid as a chelating ligand. The organic ligands present in the samples heat-treated at 110 and 220°C retard the decomposition of dimethyl disulfide and the formation of the sulfide phase but make the catalyst more active than the samples calcined at higher temperatures.

Complexes forming from ammonium paramolybdate, orthophosphoric acid, cobalt or nickel nitrate, and carbamide in solution and their use in the preparation of diesel fuel hydrodesulfurization catalysts

It is demonstrated by 14N, 17O, 31P, and 95Mo NMR spectroscopy that the heteropolyanion [P2Mo5O23]6− forms in impregnating solutions containing orthophosphoric acid, ammonium paramolybdate, cobalt or nickel nitrate, and carbamide. The anion forms labile complexes with Co2+ or Ni2+ cations by coordinating to them through terminal oxygen atoms of the MoO6 octahedra and outer oxygen atoms of the PO4 groups. The catalysts prepared by supporting these complexes on Al2O3 are highly active in diesel fuel hydrodesulfurization. They compare well with the best foreign analogues and are superior to most of the Russian commercial hydrodesulfurization catalysts.

Highly effective water adsorbents based on aluminum oxide

A method of preparation of a stable, high performance water adsorbent with the phase composition η-Al2O3 + γ-Al2O3 + χ-Al2O3 from thermally activated hydrargillite has been developed. The synthesis procedure does not involve a reprecipitation stage. The resulting adsorbent has a high specific surface area (400 m2/g) and a mean pore diameter of 3.5 nm or below. The static capacity of the adsorbent reaches 24.2 g H2O per 100 g of sorbent, and its dynamic capacity is 8.2 g H2O per 100 g of sorbent. Service life tests showed the stability of the adsorbent in multiple sorption-desorption cycles. The minimum dew point in drying is −58.8°C.

Dependence of the properties of Ce-Zr-Y-La-M-O systems on synthetic conditions and on the nature of the transition metal M (Mn, Fe, Co)

The effects of synthetic conditions, component ratios, and the nature of the transition metal on the physicochemical and catalytic properties of Ce-Zr-Y-La-M-O (M = Mn, Fe, Co) systems are studied. The Ce-Zr-Y-La-M-O samples precipitated at ∼23°C and calcined at 600°C are single-phase and are solid solutions with a fluorite structure, which persists upon calcination at 1150°C. The Ce-Zr-Y-La-Fe(Co)-O samples precipitated at 70°C and calcined at 1150°C consist of two solid solutions, one cubic, and the other tetragonal. The specific surface area (Ssp) of the samples precipitated at ∼23°C and calcined at 600°C increases in the order Ce-Zr-Y-La-O < Ce-Zr-Y-La-Mn-O < Ce-Zr-Y-La-Co-O ≈ Ce-Zr-Y-La-Fe-O. The specific surface area of the samples precipitated at 70°C is independent of M and is ∼110 m2/g. Calcination at 1150°C reduces Ssp approximately by two orders of magnitude. The TPR of the unpromoted systems in H2 proceeds in two steps at 600–650 and 750–840°C. The introduction of M decreases the reduction temperatures and gives rise to a lower temperature peak between 150 and 300°C. The most effective promoter is cobalt. The fluorite-type catalysts containing no noble metal are active in NO reduction (XNO ≈ 100%) at Treact = 400–450°C. The cobalt-containing catalysts are the most active in the oxidation of CO (Xmax = 28%) and hydrocarbons (Xmax = 4.3%).

Synthesis of NiW/Al2O3 hydrotreating catalysts from ammonium paratungstate using chelating agents

Procedures are suggested for preparing NiW/Al2O3 catalysts using ammonium paratungstate as a tungsten source and citric acid and D(+)-sorbitol as chelating agents. The catalysts prepared using the suggested reagents are characterized by increased dispersity of the sulfide component compared to the NiW/Al2O3 catalyst prepared by the traditional procedure using ammonium metatungstate and nickel(II) nitrate. In transformations of dibenzothiophene, quinoline, and naphthalene, the NiW/Al2O3 catalysts prepared using ammonium paratungstate and citric acid or D(+)-sorbitol considerably surpass in the activity the NiW/Al2O3 catalyst prepared by the traditional procedure.

A new catalyst for the deep hydrotreatment of vacuum gas oil, a catalytic cracking feedstock

A new CoNiMo/Al2O3 deep vacuum gas oil hydrotreatment catalyst designed for the production of catalytic cracking feedstocks containing 200–500 ppm of sulfur is developed. The method for its preparation includes the following stages: the preparation of a support with specified textural, strength, and granulometric characteristics; the synthesis of bimetallic (Co-Mo and Ni-Mo) complex compounds in solution; and their deposition and drying. The new sample is compared to current domestic and imported industrial analogs according to their physicochemical (texture, morphology, active phase structure) and catalytic characteristics and analyzed. It is shown that the catalyst allows hydrotreatment at temperatures 5–20°C lower and target fraction yields 4–13% higher than all the reference samples. The high activity of the new catalyst is due to the formation of one-layer trimetallic Co(Ni)MoS phase particles at the stage of its sulfidation. The catalyst preparation technique is ready for industrial use (OOO Sintez, Barnaul, 1000 t/yr), and the principal technological regimes of the hydrotreatment of vacuum gas oil on the developed catalyst are determined.

The use of X-ray absorption spectroscopy for developing new-generation Co-Mo catalysts of hydrotreating of diesel fuel

The immediate problem facing the Russian petroleum refining industry is to turn to the production of gasoline complying with European standards [1]. Nowadays, only 12 of the 27 large Russian oil refinery plants have mastered the production of low-sulfur diesel fuel containing less than 0.05% sulfur [2]. Almost all diesel fuel that meets Euro 2, Euro 3, and Euro 4 standards is produced with the use of foreign catalysts since domestic catalysts do not have the required activity level. In this context, Russian industry should proceed as soon as possible to produce new-generation heterogeneous catalysts in which all surface compounds are active centers of hydrorefining reactions. According to the basic principles of the preparation of such catalysts expounded in [3], active center precursors—bimetallic Co‐Mo compounds—should be obtained when preparing an impregnating solution and the structure of these compounds should remain unaltered during the genesis of catalysts. The existence of such a structure in an oxide precursor of hydrorefining catalysts will ensure the formation of highly active disperse sulfide particles during the sulfiding step. To purposefully use this approach, the state and structure of catalyst active component precursors should be thoroughly monitored at all stages of their preparation. The most suitable for this purpose is X-ray absorption spectroscopy, which makes it possible to identify the structure of compounds synthesized in solution and on the support surface during catalyst preparation [4]. In this paper, we report the results of the EXAFS and XANES study of the structure of bimetallic oxide precursors of the active phases of hydrorefining Co‐Mo catalysts. A bimetallic compound and allied catalyst were synthesized from the ammonium salt of the tetranuclear anion [Mo 4 (e 6 c 5 O 7 ) 2 O 11 ] 4– . Solutions and cata

Synthesis of boehmite and hematite by joint hydrolysis of carbamide, aluminum chloride, and iron(III) chloride under hydrothermal conditions

The formation of boehmite and hematite in dependence of the conditions of joint hydrothermal hydrolysis of carbamide and a mixture of aluminum and iron(III) chlorides in the presence of K, Na, Ca, and Mg chlorides at T = 160–200°C and P = 0.6–1.6 MPa was studied. It was shown that the amount of boehmite and hematite being formed in hydrolysis of Al and Fe chlorides strongly depends on pressure, temperature, hydrolysis duration, and composition of the model mixture of Al, Fe, Mg, Ca, K, and Na chlorides. It was found that a complete hydrolysis of AlCl3 and FeCl3 with 99% yield of boehmite and hematite occurs at the stoichiometric ratio between carbamide and aluminum and iron chlorides in the starting solution, whereas mostly iron oxyhydroxide [goethite FeO(OH)] and aluminum oxychloride [Al17O16(OH)16Cl3] are formed at nonstoichiometric ratios.