Vol 9, No 3 (2017)

Catalysts on resistive supports, namely, on the thermally stable metal alloy fechral (FeCrAl) and carborundum (silicon carbide SiC) were studied in the pyrolysis of methane into acetylene. The active components chosen for deposition on carborundum were oxides corresponding to those present on the surface of the heat-treated fechral alloy: iron, chromium, and aluminum oxides, as well as zirconium and silicon oxides. The deposition of oxides on carborundum leads to an increase in methane conversion compared to the starting carborundum. The maximum acetylene selectivity was obtained using the ZrO₂/SiC and Al₂O₃/SiC catalysts. In contrast, the deposition of the same oxides on fechral leads to a decrease in the activity and acetylene selectivity compared with those of the starting heat-treated fechral. On the other hand, the deposition of oxides on fechral results in an increase in the temperature range of the catalyst operation and its stability over time. In the case of carborundum, the deposition of oxides does not affect these characteristics. The study of the starting supports fechral and carborundum and supports with metal oxides showed that high acetylene selectivity correlates with the formation of carbon fibers on the catalyst surface. These fibers mainly form on the surface of alumina, zirconia, and silica.

The vapor-phase dehydration of glycerol on the heterogeneous catalyst 0.5B₂O₃/γ-Al₂O₃ (BAO-1) was studied. The kinetic model of the process was developed based on the data obtained in a differential reactor. To evaluate the kinetic constants of the generalized mathematical models of the kinetics of vapor-phase dehydration of glycerol, we used the differential evolution method implemented in the Mathematica 5.0 program. The calculated activation energy of the target reaction of acrolein formation was 50.18 ± 0.11 kJ/mol. The adequacy of the obtained equations was assessed using the Fisher test. The optimum conditions of the vaporphase dehydration of glycerol were determined using the proposed kinetic equations (reaction temperature 330°C, glycerol concentration in the supply stream 30%, and catalyst load 0.0338 L/(g_cat min). The obtained data may be used in calculations for large units for acrolein production by glycerol dehydration.

A new technology for alkylation on solid AlkiRAN-GPN catalyst with process performance characteristics and an attained material balance competitive with existing sulfuric and hydrofluoric acid alkylation technologies is presented. Data on the effect such parameters as temperature, pressure, iso-butane: olefin ratio, and feedstock hourly space velocity (FHSV)) have on the process’s performance characteristics are given, and their optimum values are recommended. It is shown that using a sectioned reactor at a constant inlet iso-butane: olefin ratio ensures a higher internal ratio of these components and an increase in the total concentration of alkylate in the reaction products at a specified internal iso-butane: olefin ratio. This also lengthens the period of catalyst interregeneration with no losses in the process’s productivity and selectivity. The use of a zeolite based on faujasite in the rare-earth element–calcium form (REECaHY) and ultrastable zeolites as catalysts is substantiated. Higher values of olefin conversion and the alkyl gasoline yield are observed when these zeolites are used. To test the new technology, a demonstration plant of iso-butane alkylation with olefins on heterogeneous catalysts with an alkylate production capacity of 1 t/day is constructed. The results from studies are to be used in developing the basic design of an industrial plant. The construction of the first industrial plant of alkylation on a heterogeneous catalyst with an alkyl gasoline production capacity of 100000 t/year is planned at AO Gazprom Neft Moscow Oil Refinery.

It is proposed that the sulfide NiMo system supported on alumina-SAPO-31 composite (NiMo/Al₂O₃-SAP catalyst) be used to obtain high-quality diesel fuel from a mixture of straight run diesel (SRGO) and light cycle oil (LCO) produced by fluid catalytic cracking (FCC). It is shown that the use of this catalyst ensures the synthesis of diesel fuel of higher quality upon hydroprocessing a feedstock with 30 wt % LCO, compared to the traditional sulfide NiMo/Al₂O₃ or CoMo/Al₂O₃ catalysts. It is found that the content of aliphatic hydrocarbons is raised in the products of hydrotreatment, compared to the initial feedstock. This confirms the ability of NiMo/Al₂O₃-SAP catalyst to facilitate the reaction of ring opening. Using the proposed catalyst should improve the quality of diesel fuels obtained via the hydroprocessing of LCO-containing feedstock.

A new CoMo catalyst for selective hydrotreating of FCC gasoline has been developed; the catalyst is intended for the production of hydrotreated gasoline with up to 10 ppm of sulfur and with a research octane number decreased by less than 1.0. The new catalyst allows hydrotreating of FCC gasoline without its preliminary separation into the light and heavy fractions. The hydrotreating conditions were as follows: hourly space velocity 2.2 h^–1, temperature 270°C, pressure 2.5 MPa, H₂/feed = 150 m³/m³. The high degree of hydrodesulfurization at minimum decrease in the octane number is achieved due to the high activity of the developed catalyst in hydrodesulfurization of the sulfur-containing components of the feedstock and conversion of reactive high-octane olefins of FCC gasoline into less reactive derivatives with high octane numbers. The catalyst is a CoMoS phase deposited on a support containing amorphous aluminosilicate and γ-Al₂O₃. The method for the preparation of the catalyst is adapted to the equipment of Russian plants and feedstocks. The parameters of hydrotreating using this catalyst ensure the hydrotreating of FCC gasoline to a residual sulfur content of less than 10 ppm with minimum redesign of the equipment currently available at Russian refineries.

Unsupported nickel–molybdenum and cobalt–molybdenum sulfide catalysts are synthesized via the in situ decomposition of water-soluble bimetallic precursors in a hydrocarbon feedstock using nickel–molybdenum and cobalt–molybdenum complexes with citric, oxalic, succinic, glutaric, and tartaric acids as precursors. The sulfide catalysts are characterized by means of transmission electron microscopy and X-ray photoelectron spectroscopy. The catalyst activity in the hydrogenation of bicyclic aromatic hydrocarbons and the hydrodesulfurization of dibenzothiophene is studied. The effect the composition of the precursor solution in the hydrocarbon feedstock emulsion has on the activity of the resulting catalyst is determined. It is shown that the activity reaches high values even after 1 h of reaction. The hydrogenation of mono-, di-, and trimethylnaphthalenes and ethylnaphthalene is studied. The optimum promoter-to-molybdenum ratio (0.25: 1) is found. It is shown that the catalyst activity does not fall during recycling, due to the elimination of the negative effect of water contained in the emulsion, which results in oxidation of the catalyst surface. After the second reaction cycle, the catalyst particles are longer and have a greater number of MoS₂ layers than the respective parameters of the catalyst particles after the first cycle. XPS shows that the content of oxygen on the catalyst’s surface falls during recycling, while the fraction of metals in the sulfide environment and the sulfur in the sulfide state grows.

The full cycle of bioethanol production from pretreated oat hulls is scaled for a pilot plant. The one-stage pretreatment of oat hulls with a dilute nitric acid at atmospheric pressure is scaled for a 250-L reactor. The total amount of hydrolysable polysaccharides in the resulting substrate is 87.2%. Using the commercially available enzyme preparations CelloLux-A and BrewZyme BGX and the industrial strain BKPM Y-1693 of Saccharomyces cerevisiae yeast, the process of enzymatic hydrolysis and alcoholic fermentation is successfully scaled for a 63-L reactor. The scaling factor is 1: 400. Bioethanol is obtained with a high yield of 17.9 daL/t. After rectification, the test sample of bioethanol meets the standards for high-purity alcohol from food raw materials according to the mass concentration of aldehydes, esters, and by the content of methanol.

Part 3 of the review discusses the modern aspects in the biotechnological synthesis of the valuable chemicals derived from the lignocellulosic biomass, including ethanol, n-butanol, isobutanol, 2,3-butanediol, and lactic and succinic acids. A comparative characteristic of different approaches (including SHF, SSF, SSCF and CBP) toward biosynthesis of valuable products is given. It is shown that the consolidated processing of lignocellulose into the valuable chemicals is a promising approach toward their direct synthesis by fermentation, but remains less efficient than other processing methods. Development of genetic engineering tools and the application of synthetic biology will allow to develop more efficient strains and advanced biotechnological processes for lignocellulose processing.