卷 8, 编号 2 (2016)

Comparative tests of palladium, nickel–molybdenum, and lanthanum–magnesium–nickel catalyst samples with aluminium oxide are performed to select an effective catalyst for the hydrodechlorination of methylene chloride and chloroform. The tests are conducted in a flow reactor with a fixed catalyst layer at 300°C with a contact time of 3.8 s and a hydrogen-to-methylene chloride molar ratio of 3 : 1. The nickel–molybdenum catalyst is found to be the one most effective. Improvements to the technological process scheme for the priority production of ethylene to be used in obtaining vinyl chloride are proposed. These improvements require the production of ethylene via an additional stage of the pyrolysis of methane homologues isolated from natural gas and formed in the pyrolysis of methyl chloride, along with a stage of polychloromethane hydrodechlorination.

Quantitative data on the effect of process parameters on the main features of the liquid-phase epoxidation of propylene with an aqueous solution of hydrogen peroxide in the presence of extruded titanium silicate in a methanol medium are obtained. The effect of the solvent concentration (13.7–19.1 mol/L), the initial propylene: hydrogen peroxide ratio ((2–5) : 1), and the temperature (30–60°C) on the yield of the target product (propylene oxide) and such byproducts as 1,2-propyleneglycol, 1-methoxy-2-propanol, and 2-methoxy-1-propanol, is studied. The observed characteristics are used as a basis for recommendations concerning the conditions of propylene oxide synthesis in a continuous laboratory setup.

The effect of the mordenite acidic modulus (SiO₂/Al₂O₃, 20 and 30) of Pt/MOR/Al2O3 catalysts on the heptane isomerization reaction is investigated. The content of zeolite in the catalysts is varied from 10 to 50 wt %, with platinum applied to the samples from solutions of different precursors: H₂PtCl₆ and [Pt(NH₃)₄]Cl₂. It is established via the TPD of ammonia and FTIR spectroscopy (the adsorption of NH₃ and СО) that the total acidity of zeolite falls as the modulus grows: the number of Brønsted (BAC) and Lewis (LAC) acidic sites is reduced, accompanied by an increase in the strength of their acidity. The catalysts are tested in the n-heptane isomerization reaction. It is shown that the selectivity of n-heptane isomerization falls substantially when the acidic mordenite modulus is increased from 20 to 30.

Iron-containing catalysts supported on mesoporous silica samples that differ in the methods of their preparation (commercial KSS silica gel, MSM-41 mesoporous silicalite, and silica gels obtained under laboratory conditions by means of spray drying and drying in supercritical СО₂) are synthesized. Their porous structure is studied via low-temperature nitrogen adsorption. Their catalytic activity and stability in the oxidation of carmoisine (an anionic dye) with a 3% hydrogen peroxide solution in water at 60°C and рН 3 are compared. The initial carmoisine and catalyst concentrations in solution are 20 mg/L and 3 g/L, respectively, and the molar Н₂О₂/carmoisine ratio is 459/1. The KSS-based catalyst demonstrates the highest activity and stability with respect to the outwashing of an active component into a solution: the conversion of carmoisine on this catalyst is as high as 99% for 30 min, while the concentration of iron ions in solution (0.27 mg/L) does not exceed the maximum allowable concentration. After the support is preimpregnated with aluminum, the degree of iron outwashing into a solution is more than halved. The synthesized catalysts are of interest with regard to the purification of waste water containing organic admixtures.

Ethanol dehydration to ethylene is tested on industrial alumina, a support for hydrotreating catalyst IK-GO-1 (AO_IK-GO-1), sorbents AN-2N and AOK-63-22, and catalyst AOK-78-59. Activity is measured in a plug-flow reactor in the temperature range of 375–400°C at a contact time of 0.3 s, and the effect of the process temperature on the conversion of ethanol and the selectivity toward target and secondary products is determined. A correlation between the specific activity and mass fraction of sodium is found for samples with homogeneous phase composition. It is shown that the activity of the investigated industrial catalytic systems based on alumina in the dehydration of ethanol to ethylene changes in the order AO_IK-GO-1 > AN-2N > AOK-63-22 > AOK-78-59.

A series of mixed polyferrites of β"-alumina type M₂Fe^IIFe_11−q^IIILn_qO₁₇, where q = 0.1–1.0; M = K, Cs, Rb; and Ln = Sc, Y, Ce, Sm, were synthesized. Their cation and electron conductivities and catalytic activity in the conversion of ethylbenzene into styrene were measured, and the relative chemical stability was determined. The mechanism of stabilization of the alkaline promoter in the catalyst structure during the doping of mixed potassium–cesium polyferrites with rare-earth oxides was considered. The requirements for the doping agent were formulated. The most promising way of stabilizing the alkaline promoter in a mixed potassium–cesium polyferrite system was shown to be the introduction of samarium oxide in amounts corresponding to q = 0.25–0.30, which is no more than 1.5 wt % based on the catalyst formulation.

This review presents an up-to-date analysis of the scientific and patent literature concerning ethanol dehydration catalysts and ethylene synthesis processes, taking into consideration the specific features of utilizing biological raw materials.

Literature published mainly between 1995 and 2015 in the field of investigations aimed at finding promising new catalysts for the industrial processing of polysaccharide components of lignocellulose biomass, for new methods to achieve these processes, and for new ways of transforming polysaccharides into valuable chemicals and fuel is reviewed. In the first section, modern methods for activating lignocellulose biomass in order to separate main components and/or treat polysaccharide feedstock (cellulose, hemicelluloses) for further processing are considered. The second will deal with catalytic acidic transformations of these components into monosaccharides and furans. The third will focus on with the main focus on the production of 5-hydroxymethylfurfurol the application of biotechnological enzymatic methods for producing valuable chemicals such as ethanol, isobutanol, lactic acid.

The effective application of a biocatalyst based on recombinant enzyme preparations obtained using Penicillium verruculosum is studied for the modification of marketable bleached sulfate hardwood cellulose. The effect of treatment with cellulase complex on the structure, morphology, and surface state of cellulose fibers is evaluated. After biocatalytic exposure, cellulose is shown to have an improved capacity for beating and the formation of bonds in paper sheets, along with greater strength than the initial cellulose. Application of the enzymatic modification of cellulose in the paper industry during biotechnological processes allows a range of problems in the efficient use of energy and resources to be solved.