In this study, the effect of the gibbsite content in bayerite on the properties of the CrO x /Al2O3 catalyst based on a support prepared from this bayerite was investigated. Two bayerites with gibbsite impurities were used for the preparation of granulated supports and CrO x /Al2O3 catalysts. The amounts of Cr in the catalysts were 5.5 +/- 0.5 and 13.1 +/- 0.5 wt %, respectively. Pure gibbsite and pseudoboehmite (binding agent) were used to prepare the reference samples. The gibbsite content in the supports was 20 wt %, 30, 80, and 100 wt %. Thermal analysis, laser diffraction method, 1H MAS NMR, low-temperature nitrogen adsorption-desorption, TPD-NH3, XRD, potentiometric titration of Cr6+, ESR, Raman spectroscopy, and XPS were used to study the initial powders of alumina precursors, Al2O3 supports, and CrO x /Al2O3 catalysts. The catalysts were tested in the isobutane and butane dehydrogenation processes. The gibbsite content in bayerite powder correlates with the content of the chi-Al2O3 phase in the support. The presence of the chi-Al2O3 phase in the support promotes a higher proportion of Cr5+ and a lower proportion of Cr3+ in the Cr2O3 species of catalysts containing 5.5 +/- 0.5 wt % Cr. It further leads to a decrease in the number of active sites and a decrease in the activity in isobutane conversion and isobutene yield while selectivity remains unchanged. As the content of the chi-Al2O3 phase in the support increased, the total Cr6+ content and the water-insoluble Cr6+ content also increased in catalysts containing 13.1 +/- 0.5 wt % Cr. Increasing the chi-Al2O3 content in the support also led to decreased n-butane conversion and butadiene yield.

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 of the influence the type of plasticizing organic/inorganic agents on structural-mechanical properties (plastic strength, molding pressure, limit shear stress, greatest plastic viscosity, plasticity and etc.) of the pseudoboehmite pastes is presented. Samples of the pastes were prepared using plasticizing agents of organic nature (acetic, malic, tartaric, oxalic and citric acids and diethyelen glycol) and inorganic nature such as nitric and phosphoric acids, aqueous ammonia solution and ammonium hydrocarbonate. Our results suggest the pastes plasticized with nitric/phosphoric acids or with diethylene glycol demonstrate the highest plastic strength in the set. Plastic strength values were found to correlate well with the molding pressure necessary for the paste shaping through a piston extruder. The structural-mechanical type of paste was determined using a modulus of elasticity, viscosity and limit shear stress. All pastes were found to be suitable for extrusion molding and did not belong to SMT types 0 and III. The plasticizing agent was found to affect SMT type of paste. Paste types I, II, IV, and V were obtained by changing the plasticizing agent. Alumina granules without visible defects and with sufficient crush strength value were prepared using the investigated pastes. This allows them to be used as supports/adsorbents/catalysts for industrial processes.

A series of supported Ni phosphide bifunctional hydroisomerization catalysts (Ni2P/ZSM-23/Al2O3) was synthesized by means of Ni hypophosphite reduction at different temperatures. The structure and morphology of Ni phosphide phase were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface chemical analysis was performed using X-ray photoelectron spectroscopy (XPS). The hydro/dehydrogenation and acid functions of catalysts were characterized by CO chemisorption, NH3-TPD and IR-spectroscopy of adsorbed pyridine (IR-Py). The reduction of supported precursor at the temperature lying in the range of 550–650 ⁰С resulted in high activity and iso-selectivity in n-decane conversion. The reduction of the supported component at 500 ⁰C or re-reduction of ex-situ reduced and passivated catalysts at 450 ⁰C led to the formation of impurities of other Ni phosphides such as NiP and Ni5P4 and had a negative impact on n-decane conversion. Both the Brønsted acidity and Ni2P dispersion of the catalysts declined with increasing Ni2P content which were accompanied by a drop in their activity without loss of iso-selectivity.

The kinetics of n-butane dehydrogenation to butadiene is studied with temperature (T) variation of 550–625°C, duration of dehydrogenation stage (t) of 5–30 min, and space velocity (V) of 4400–35 200 h−1 on industrial catalyst K-CrOx/γ-Al2O3 at a fraction of 56–94 μm. The catalyst is stabilized before studies. The granulated catalyst in a reduction–dehydrogenation–regeneration cycle at 593°C, and then as a fraction of 56–94 μm in dehydrogenation–regeneration cycle at 650°C. The maximum selectivity toward butadiene of 25 mol

The authors formulate a mathematical model of the non-stationary single-stage dehydrogenation of n-butane to butadiene in an adiabatic fixed-bed reactor for the first time, based on a kinetic model that describes the formation of coke and primary and secondary by-products on a K-CrOx/γ-Al2O3 catalyst. The model allows prediction of the yield of butadiene and other products depending on the activity of the catalyst, the composition of initial mixture, the period of the dehydrogenation cycle, and the degree of catalyst dilution with an inert material (including the non-uniform dilution of a catalyst with an inert material along the bed length). It also allows assessment of the temperature regime of the catalyst’s operation and the degree of its coking along the bed. It is shown that the model is adequate for describing the conversion of n-butane, the formation of butadiene and butylene, the accumulation of coke, and the loss of catalyst activity using test calculations of main technological parameters as an example.

The beneficial impact of carbon coated alumina (C@Al2O3) implemented as support for the CoMoS hydrotreating catalyst has been demonstrated. A series of C@Al2O3 supports with varying carbon contents were obtained by pyrolysis of sorbitol preliminarily impregnated in alumina from an aqueous solution. It was found that carbon coating positively affects the formation of the high-active CoMoS phase. However, control of the carbon content from 2.3 to 11.3 wt % is essential to maintain the sulfide particles dispersion and textural properties. CoMoS/C@Al2O3 catalysts demonstrated superior hydrodesulfurization activity compared with CoMoS/Al2O3. The hydrodenitrogenation activity of most CoMoS/C@Al2O3 samples is similar to CoMoS/Al2O3 but decreases when the carbon content in the support exceeds 11.3 wt %. The determining factor in improving the CoMoS/C@Al2O3 hydrodesulfurization activity is the formation of defective graphene fragments, which partially cover the alumina surface and help to reduce the support acidity and, therefore, metal-support interaction while maintaining the textural characteristics.

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.

In this work, a series of ZSM-23 zeolite samples having different acidity due to various Si/Al ratios (30, 50, and 100) was synthesized using DMFA as a template. Two series of bifunctional Ni/ZSM-23 catalysts were prepared: the first one with different Ni content and the second one with different zeolite acidity. Samples were characterized by a set of physicochemical methods and tested in a hexadecane isomerization reaction. It was shown that an increase in the nickel content from 2 to 5 wt % significantly enhanced hexadecane conversion and iso-C-16 yield. The catalyst activity depends almost linearly on the zeolite acidity. The maximum iso-C-16 yield of 76 wt % was achieved over Ni/ZSM-23 catalyst with a Si/Al ratio of 50 having moderate acidity. The results demonstrate the prospects for implementing low-cost nickel-containing zeolite catalysts for an industrially important reaction such as the hydroisomerization of middle distillates and heavier petroleum fractions.

A study was made of the efficiency of trapping solid microparticulates contained in diesel fuel for catalyst loading – an analogue of an industrial package of guard beds of hydroprocesses. The package of catalysts consisted of catalyst granules ranked by shape and size: segmented rings, hollow cylinders of two standard sizes and trilobe shape. The experiments were carried out in the trickle flow regime with a constant ensemble of microparticulates – iron scale with a size of 5 to 150 μm at the inlet of the catalysts loading. It was found that the penetration coefficient of the catalysts loading of the guard beds did not change significantly (K ≈ 0.985) during the experiment. At the same time, a linear increase in the pressure drop on the catalysts loading of the guard beds with a height of 17 cm from 220 to 408 Pa was observed which occurred as a result of the trapping of solid microparticulates by the catalyst granules. The theoretical estimate of the initial pressure drop (228 Pa) coincides with the experimental data (220 Pa) with good accuracy.

The mathematical model of the adiabatic fixed-bed catalytic reactor for direct dehydrogenation of n-butane to butadiene operating under nonstationary conditions is formulated for the first time. The model includes kinetic equations that describe the formation of primary products, by-products, secondary products and coke on the K-CrOx /γ-Al2O3 catalyst [Cat. Ind. 2024. V. 24(1). P. xx–xx]. The model allows predicting the yield of butadiene and other products depending on the process parameters, such as the catalyst activity, the feed gas composition, the cycle time of the dehydrogenation period, the ratio of the catalyst to inert material (for both uniform and non-uniform dilution). The model allows calculating the temperature regime of the catalyst operation and the degree of its coking along the bed length. The adequacy of the model to the industrial process in the description of n-butane conversion, butadiene and butylene formation, coke accumulation and loss of catalyst activity is shown on the example of test calculations of the main process parameters.

The kinetics of dehydrogenation of n-butane to butadiene was studied on K-CrOx /γ-Al2O3 catalyst particles of 56–94 μm size by varying the temperature T = 550÷625 °C, the time of catalytic step TOS = 5÷30 min, and the space velocity GHSV = 4400÷35200 h–1. The catalyst was similar to the commercial one. Prior to the studies, the catalyst granules were stabilized during the reduction-dehydrogenation-regeneration cycle at 593 °C, then the catalyst particles milled to a size of 56–94 μm were stabilized during the dehydrogenation-regeneration cycle at 650 °C. The highest butadiene selectivity of ~25 mol.% was obtained at n-butane conversion of 26–30 % (GHSV = 35200 h–1) at T = 600 °C and TOS = 5 min, and the highest butadiene yield of ~10 mol.% was obtained when the conversion was increased to ~50 % (GHSV = 8800 h–1) under the same conditions. Increasing T to 625 °C, TOS to 30 min and decreasing GHSV to ~4400 h–1 resulted in an increase in by-product selectivity to ~50 mol.%. It was found that the observed activation energy of product formation rates decreases in the series: by-products > butylene > butadiene. A kinetic model is proposed that takes into account the formation of butadiene via butylene, the formation of by-products such as ethane/ethylene and methane/propylene in the butylene hydrocracking reactions, and the secondary conversion reactions of by-products. Inhibition of dehydrogenation reactions by components of the reaction mixture, coke formation and its effect on catalyst activity are also considered in the model. The adequacy of the kinetic model is confirmed by good agreement of the calculated results with the experimental data.

The present study investigates the effects of heat treatment temperature on the physicochemical properties of bulk granular Ni–Mo–W catalysts. A series of bulk catalysts were synthesized and characterized by X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, CHNS elemental analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. To evaluate the catalytic activity in hydrodesulfurization and hydrodenitrogenation reactions, the catalyst samples were tested in hydrotreating of vacuum gasoil. It was found that the bulk granular catalysts calcined at 400°C and lower temperatures were mainly X-ray amorphous. In the samples calcined above 400°C, a nickel molybdate phase was predominant. In these samples, the content of an active sulfide phase after sulfidation was lower than that in the samples prepared from X-ray amorphous oxide precursors. The test data showed that the catalyst calcined at 300ºC exhibited the highest activity in the hydrodesulfurization of vacuum gasoil.

The dynamics of the silicon sorption on the NiMo/Al2O3 guard-bed catalyst containing 2.0 wt

The effect of the presence of water in the feedstock on the activity of CoMoP/Al2O3 catalysts modified with La during the hydrotreating of the diesel fraction was studied. A total of four experiments were carried out: in the first there was no water, in the other two experiments water was supplied to the reactor mixed with gasoil for a long and short period of time, and in the fourth, water was first supplied to the reactor, and then the reaction was carried out only with the diesel fraction. The catalysts were studied using the nitrogen adsorption–desorption method, UV–vis spectroscopy, FTIR, HRTEM, EDX, XPS, XRD. The activity of the catalysts was judged by the residual content of sulfur and nitrogen in the samples after the reaction. It was found that the addition of water to the gasoil fraction leads to a strong deactivation effect on the catalyst in targeted hydrotreating reactions due to structural changes in the active component of the catalyst and its distribution on the support surface, the decrease in number of active sites due to the oxidation of the active component edges and the segregation of cobalt atoms with a possible incomplete recovery of catalytic activity due to re-sulfiding after water supply stops.

An efficient strategy for the synthesis of nanostructured composite supports for CoMoS hydrotreating catalysts has been proposed. The synthesis concept is based on the growth of multi-walled carbon nanotubes (MWCNTs) on alumina crystallites modified with Fe2Co nanoparticles. The morphology and structural characteristics of the obtained MWCNT@Al2O3 supports were tuned by varying Fe2Co content. A comprehensive analysis using advanced techniques revealed the optimal content and structural characteristics of MWCNTs in composite supports that positively affect the morphology of the sulfide component. It has been established that for the best CoMoS/MWCNT@Al2O3 catalyst, which is characterized by the highest dispersion of sulfide component and CoMoS phase content, the activity in dibenzothiophene hydrodesulfurization and quinoline hydrodenitrogenation significantly exceeds the activity of CoMoS/Al2O3 and CoMoS/MWCNT catalysts. The proposed approach can be applied to improve the activity of both conventionally used hydrotreating catalysts and catalysts for other practically important processes by carefully tuning metal-support interaction.

The results of development and application of oxide materials and bi(tri)metallic complexes as catalysts for hydrotreating and hydrocracking of oil fractions were analyzed. The possibility of controlling the properties of hydrotreating catalysts by chemical modification of the alumina-based support was demonstrated experimentally. The effect of morphological characteristics on the yield of middle oil distillates in the hydrocracking of vacuum gas oil was demonstrated in relation to catalysts containing Y type zeolites. Catalytic materials for trapping metals (V, Ni, Si, As) from oil fractions were developed.

The influence of alumina precursor (pseudoboehmites) in CoMo/ASA + Al2O3 catalysts on catalytic activity in FCC gasoline hydrotreating has been studied. Pseudoboehmites prepared by alcoholate, precipitate and hydro-thermal technologies were used. Parent powders, supports and catalysts were characterized by low-temperature N2 adsorption, TPD of ammonia, STEM, HRTEM, UV-vis spectroscopy. Catalysts were tested in hydrotreating of the model FCC gasoline feedstock. It is shown that the choice of pseudoboehmite has significant effect on textural, acid and mechanical properties of supports and catalysts, as well as dispersity of the active phase. The type of pseudoboehmite affects the amount of tetrahedral cobalt in catalysts that changes surface activity per 1 g of the catalyst. The linear dependence between the ratio of the medium and weak acid sites and catalyst selectivity was found. It is established that isomerizing activity is higher than the hydrogenating one, when medium/weak acid sites ratio in the catalyst is lower than 1.85.

The present report is devoted to refining of thermolysis oil (TO), which was obtained from the mixture of different plastics and contained 2.24% of chlorine. The process of refining of thermolysis oil includes combi-nation of hydrotreating of TO (80%) and SR VGO (20%) mixture with NiMo supported catalysts. The following process includes FCC treatment of the obtained hydrotreating products. All used conditions were typical for industrial FCC process of SR VGO with its preliminary hydrotreating. The influence of hydrotreating catalyst type and hydrotreating temperature on the composition and properties of hydrotreating products was studied. Moreover, the effect of these parameters on the composition and yields of FCC products was established. The main reasons of hydrotreating catalysts deactivation during refining of Cl containing thermolysis oil were investigated by XPS, HAADF, HCNS-analysis. It was revealed that the best hydrotreating temperature was 360 degrees C, while the best used catalyst was NiMoP/Al2O3.