Catalysis in Industry最新文献

The synthesis of glycerol carbonate from glycerol and dimethyl carbonate when using strongly basic styrene–divinylbenzene anion-exchange resins Dowex 1 × 2, Dowex 1 × 4, and Dowex 1 × 8 in the OH-form is studied. The resins are characterized by different degrees of crosslinking of their polystyrene matrices (the contents of divinylbenzene are 2, 4, and 8 wt. %, respectively). Synthesis is performed at 90–105°C, and the molar ratio of dimethyl carbonate to glycerol is 2 : 1. The yield of glycerol carbonate is shown to depend on the degree of crosslinking of the anion-exchange resin, since it falls as the degree of crosslinking rises. The highest degree of the conversion of glycerol (95%) and its selectivity toward glycerol carbonate (45.5%) are observed when using Dowex 1 × 2 and the reaction proceeds at 105°C for a period of 5 h. Advantages of considered systems over other anion- and cation-exchange resins proposed in the literature are noted.

A study is performed by using a zinc–copper catalyst for the steam reforming of CO NIAP-06-06 in the synthesis of methanol. The catalyst is characterized via the TPV of N₂, XRF, and SEM. It is tested in the synthesis of methanol in flow and circulation modes at a pressure of 5.0 MPa, GHSV of 3000 h⁻¹, and the 220–260°C range of temperatures. It is shown that the catalyst has high activity and selectivity in synthesizing methanol from gas obtained in the ratio H₂ : CO = 3.9 via the steam reforming of methane. Using a series of tubular catalytic reactors in the technological mode of a flow circle allows more than 70% of the CO to be processed and raw methanol to be obtained with a concentration of 95%. The performance of the catalyst for methanol is 427.7 kg/(({text{m}}_{{{text{cat}}}}^{3}) h) in the circulation mode.

A study is performed of the main ways of preparing aluminum oxides; the advantages of products of the thermal activation of hydrargillite (gibbsite) for preparing catalysts, supports, and sorbents; factors that influence the products of thermal activation and aluminum oxides according to the technology of thermal activation; and examples of effectively using products of the centrifugal thermal activation of hydrargillite to prepare catalysts, supports, and sorbents.

The effect of acid activation with 0.125–0.5 M Н₂SO₄, HCl, and HNO₃ on the physicochemical properties and catalytic performance of natural clay (the Mukhartalinskii deposit) containing 95% montmorillonite (MM) was investigated in the synthesis of solketal [(2,2-dimethyl 1,3-dioxolan-4-yl)methanol] from glycerol and acetone. The reaction rate and selectivity toward solketal are shown to depend on the type and concentration of acid. Both the yield of solketal and the reaction rate rose with increasing acid concentration, which correlates with the increase in the number of Brønsted acid sites. The efficiency of the system was found to diminish in the order MM/HCl > MM/HNO₃ > MM/H₂SO₄ as the surface acidity decreased.

Ni-containing catalysts are obtained on the basis of carbon mineral supports produced using sapropel and studied during the catalytic hydroliquefaction of sapropel. It is found that catalysts on supports obtained from mineral-type sapropel are more active than ones on supports based on organic-type sapropel, while bimetallic NiW catalysts exhibit higher activity than monometallic nickel catalysts, regardless of the nature of the support. It is shown that both the nature of the deposited metal and the support composition affect the conversion of the organic matter of sapropel and the composition of liquid products. The liquid products of hydroliquefaction contain mainly nitrogen- and oxygen-containing compounds. The maximum yield of hydrocarbons C₅–C₂₁ is obtained for catalysts on supports obtained from mineral-type sapropel. Liquid products of hydroliquefaction of sapropels are similar in composition to biofuels from other renewable raw materials and can be included in existing schemes for further processing.

This review focused to the discussion of the results from recent research in a promising area of the complex processing of lignocellulosic biomass: reductive catalytic fractionation (RCF). The effect catalysts, co-catalysts, solvents, sources of hydrogen, and the nature of lignocellulosic raw materials on the selectivity in the production of monomeric lignin products is considered. Heterogeneous catalysts are mainly used in RCF processes, which allows the reductive depolymerization of lignin to obtain low molecular weight compounds while maintaining the carbohydrate components of the biomass. Of the considered catalysts based on platinum group and transition metals, those containing Pd, Pt, Ru, and Ni have the highest activity. The nature of the metal also affects the composition of the resulting products. For example, ruthenium catalysts produce 4-propyl guaiacol as the main product, while ones based on Ni and Pd yield 4-propanol guaiacol. Catalysts containing Mo, due to their lower hydrogenation activity, give monolignols or their esterified derivatives of while preserving the carbohydrate components of lignocellulosic biomass. However, bifunctional catalysts that contain both acidic and metallic active sites are the most efficient in RCF processes. Acid sites contribute to the breaking of etheric β-O-4 bonds, while metal sites catalyze reduction of the resulting intermediate compounds. An important aspect of selecting suitable catalysts for the RCF process is their reusability. The use of a ferromagnetic catalyst or a basket for the catalyst solves the problem of separating it from products of the process.

The production of olefins via the catalytic conversion of methanol on zeolites and zeotypes is of great interest to both the scientific community and specialists in related areas of the national economy. Due to the gradual industrial implementation of the above process, the focus of attention is gradually shifting from scientific research devoted to the synthesis and modification of zeolites and zeotypes of different structures; to studies of pilot and industrial installations; to determining the main economic and environmental indicators, both existing and planned; and to the construction of production facilities. In 2019 alone, China licensed the construction of 26 production sites with a capacity of 14 million t/yr for ethylene and propylene, and commissioned 14 enterprises with a total capacity of 7.67 million t/yr for ethylene and propylene. The established production facilities include a full cycle of coal processing that consists of coal gasification units for the production of synthesis gas; units for the production and purification of methanol and olefins; and units for the production of polyethylene and polypropylene. The total productivity of the commissioned plants is more than 21 million t/yr for ethylene and propylene. This work reviews sources published in the foreign literature over the past five years on the preparation and modification of catalysts, along with technological, economic, and environmental aspects of the production of olefins from methanol.

The current structure of the production and consumption of methanol is reviewed. The main processes of methanol processing and catalysts for their implementation are highlighted: the production of formaldehyde, hydrocarbons (MTH), olefins (MTO), and the production of hydrogen from methanol by means of steam reforming, partial oxidation, autothermal reforming, and decomposition.

The state-of-the art in the catalytic conversion of natural gas containing methane as the main component to valuable chemicals and fuels is reviewed. Methane conversion processes are of considerable importance to society; like oil, they are sources of energy, fuels, and chemicals. Direct and indirect means of methane conversion are discussed. Direct methane conversion processes are commonly thought of as the Holy Grail of modern research, since the methane molecule is extremely stable. Ways of producing synthesis gas, methanol, ethylene, formaldehyde, benzene, and other compounds are considered. The main emphasis is on processes of direct methane conversion (methane dehydroaromatization). Catalysts and the conditions for their synthesis are described, the state of active sites is studied, and a mechanism of methane dehydroaromatization is proposed. The reasons for catalyst deactivation and means of catalyst regeneration mechanism are described. The review helps summarize recent advances in heterogeneous catalysis in the field of natural gas conversion.

The ways for the production of zeolite powders, which are currently manufactuired on an industrial scale, and their conversion into grained zeolite-containing adsorbents and catalysts are studied. Some data on the Russian manufacturers of these materials are presented. A brief overview on the utilization of these materials in adsorption drying, the purification and separation of gaseous and liquid media, and the catalytic processing of hydrocarbons in Russia and worldwide is given.