Vol 11, No 1 (2019)

The effect of the temperature and exposure time of the starting aluminophosphate gels on their chemical and phase composition was studied. When the source of aluminum is its hydrated oxide (boehmite), gels with different contents of ammonium phosphate, undissolved boehmite, and amorphous aluminophosphate can be formed. The formation of a gel with dominant amorphous aluminophosphate allows selective crystallization of AlPO₄-11 of high phase purity and ~100% crystallinity. The developed procedure for the preparation of highly dispersed aluminophosphate AlPO₄-11 molecular sieves with these properties allows a transition to crystallization of silicoaluminophosphates SAPO-11—promising domestic catalysts for industrial hydroisomerization of n-paraffins in the production of Arctic diesel fuels and group III oils and isomerization of butenes.

Dimethyl ether (DME) is a promising multisource and multipurpose clean fuel and value-added chemical synthesized from syngas. This process can be either performed in a single stage (direct process) using a dual catalysis system or a two stage (indirect process) where syngas is first converted into methanol and then dehydrated to produce DME. While the dehydration reaction has been studied extensively over multiple decades, to date no review has been conducted on the catalysts involved in the methanol dehydration reaction. This work demonstrates the state of the art in catalyst preparation and analysis for this application. The dominant catalysts are studied extensively in this work, including γ-Al₂O₃ and various zeolites, such as ZSM-5, Y, beta and mordenite as well as their relevant modifications. Additionally, silica-alumina, mesoporous silicates, alumina phosphate, silicoaluminophosphates, heteropoly acids (HPAs), metal oxides, ion exchange resins and quasicrystals are discussed in this work, owing to the wide variety of catalysts available and studied for the purposes of methanol dehydration to DME.

Experimental studies of ammonia oxyethylation in a flow microchannel reactor are performed in broad ranges of temperatures (70–180°C) and residence times (0.47–3.3 min). The main products of the reaction between ethylene oxide (EO) and ammonia are monoethanolamine (MEA), diethanolamine (DEA), and target triethanolamine (TEA). It is shown that EO conversion grows along with residence time τ and reaches 90% at τ = 3.3 min. The highest selectivity toward MEA and DEA is observed at a temperature of 70°C and τ = 3.3 min. High selectivity toward TEA (84%) is achieved at short τ (0.47 min) and the maximum temperature (180°C). The TEA yield grows along with temperature and the residence time to reach 62% at τ = 3.3 min and temperatures of 155–180°C. Mathematical modeling of the ammonia oxyethylation process allows the kinetic constants of individual stages to be calculated. Differences between the obtained kinetic parameters and the literature data, due probably to using a microchannel reactor that ensures high parameters of heat and mass transfer instead of a traditional bulk triethanolamine synthesis reactor, are revealed.

In this work, the mesoporous material Al-B-SBA-15 has been obtained by direct synthesis method with Si : B : Al ratio of 10 : 0.5 : 0.5. Wetness impregnation (WI) method was used to load platinum on Al-B-SBA-15. The prepared support and catalyst were characterized by nitrogen adsorption–desorption measurement (BET), XRD, TEM, and TPD-NH₃ to investigate the influence of boron and aluminium on characteristics of the catalyst. The activity of the bifunctional catalyst was tested for hydrogenation of tetralin at 180–220°C, hydrogen pressure of 1.5–2.5 MPa for 3 h.

The hydrotreatment of pyrolysis bio-oil by hydrodeoxygenation at 6.0 MPa initial hydrogen pressure in the temperature range of 150–350°C and the presence of a NiCu–SiO₂ catalyst synthesized using the sol-gel method is studied. The stability of the catalyst including the agglomeration of active component particles and the deposition of carbon on its surface is also investigated. It is shown that the content of oxygen in the products of the hydrotreatment of lignocellulose pyrolysis liquid decreases from 37 to 15 wt % upon an increase in the process temperature. Using a CHNS-O-analyzer, it is established that the amount of coke on the catalyst’s surfaces at a temperature of 350°C decreases by 4 times, compared with that formed at 150°C. X-ray diffraction shows that increasing the process temperature results in the gradual agglomeration of particles with a subsequent reduction in their size at high temperatures due to the dissolution of active catalyst components in the reaction medium.

A comparative analysis of the main characteristics of industrial catalysts and the innovative MAK-K catalyst in the dehydrogenation of cyclohexanol was performed. The main attention was paid to a comparison of MAK-K with H3-11 (BASF), which is currently the best catalyst in terms of activity and selectivity in the temperature range 220–270°C at a feedstock space velocity of 0.6–1.3 h^–1. Both catalysts are characterized by close dependences on these parameters; MAK-K is recommended for use at lower temperatures and higher space velocities. The results of the industrial tests of MAK-K (NIAP-KATALIZATOR) loaded in an amount of 1.4 m³ in reactor 2 of the cyclohexanol dehydrogenation shop of Shchekinoazot were also presented. The high level of activity and selectivity of MAK-K was confirmed over the period of operation (more than 2000 h), and this catalyst showed that it is highly competitive in respect of the tested samples, including foreign ones.

The process of dehydrating ethanol to ethylene by varying geometrical dimensions of a ring-shaped alumina catalyst is studied using a mathematical 2D model of a multitubular reactor. The set of ring sizes determines equivalent grain size R_eq, on which catalyst’s effectiveness factor η depends in turn. A procedure is proposed for assigning grains with different geometric dimensions to four structural groups, depending on the technique used to synthesize samples with the same equivalent size R_eq. Based on this approach, a system of criteria is developed for selecting catalyst grains with the best characteristics for given conditions. The geometric sizes of grains and other parameters that ensure the highest ethylene yield at the lowest values of the pressure drop and the residence time are determined.