Catalytic systems based on SAPO-11 molecular sieves are known for their superior selectivity in the hydroisomerization of higher (C16+) n-paraffins. However, further improvement of SAPO-11-based catalysts is impeded by the lack of effective tools for controlling the morphology and size of silicoaluminophosphate crystals. The present study investigates the effects of the DPA/Al2O3 molar ratio in reaction gels on the nature of intermediate phases and on the physicochemical properties of SAPO-11 molecular sieves. SAPO-11 has been found to crystallize through the formation of different phases depending on the DPA/Al2O3 ratio: an AlPO4·2H2O intermediate at DPA/Al2O3 = 1.0, a mixture of AlPO4·2H2O and a layered silicoaluminophosphate at DPA/Al2O3 = 1.4, and a layered silicoaluminophosphate alone at DPA/Al2O3 = 1.8. Proper adjustment of this ratio provides an effective tool to control the crystal morphology, crystal size, and the porous structure characteristics of the SAPO-11 molecular sieves. It has been identified that, at DPA/Al2O3 = 1.0, cubic and lamellar SAPO-11 nanocrystals 200–400 nm in size are formed. These nanocrystals have the following textural properties: SBET = 286 m2/g; Vmicro = 0.06 cm3/g; and Vmeso = 0.21 m3/g. Furthermore, the effects of the morphology and size of SAPO-11 molecular sieve crystals on their catalytic performance in the hydroisomerization of n-hexadecane have been demonstrated. Promising catalytic systems based on SAPO-11 nanocrystals have been proposed for the hydroisomerization of C16+ n-paraffins.

This review presents an analysis of the existing concepts for the utilization of electric power for heating chemical reactors, primarily those designed for heterogeneous catalytic processes. The paper provides a brief outline of major electric heating methods in the context of chemical applications, mentions important examples of the industrial implementation of electric heating, and evaluates the prospects for industrial use of electric heating instead of conventional heating systems.

This review summarizes the current advances in the synthesis of polyoxyalkylene ethers and alkyl oxalates. It discusses the prospects for the application of these oxygenates as engine fuels and the methods for their structural modification to ensure effective control of their performance characteristics.

The study investigates catalytic conversion of polyethylene and polypropylene—in the form of 1–5 wt

The chemical engineering community has shown significant interest in investigating methods to decompose hydrogen sulfide into hydrogen and sulfur. However, there is still a lack of detailed experimental data enabling us to choose the optimal catalyst, reaction, and regeneration conditions, as well as the overall process design. The purpose of this work is to synthesize a series of catalysts and compare their catalytic activity under the same conditions, chosen on the basis of a possible large-scale H2S conversion process. To achieve this, the obtained catalysts were characterized by BET, XRD, SEM, TEM, and XPS before and after the reaction. Decomposition was conducted in a laboratory fixed-bed reactor at a temperature of 500 °C, 10 vol% of H2S in the feed, and a GHSV of 540–1000 h−1. DFT calculations evaluated the H2S bond cleavage on various catalyst surfaces. It was shown that the most promising catalyst was Ni3S2, offering an acceptable H2S conversion of 40%. We also observed that Ni3S2 catalyst regeneration could be conducted at much milder conditions compared to those previously reported in the literature. These results highlight the viability of upscaling the process with the selected catalyst.

SAPO-11 molecular sieve samples differing in the acid properties, crystal morphology and size, and secondary pore structure characteristics were obtained by crystallization of reaction gels with the SiO 2 /Al 2 O 3 molar ratios of 0.1 and 0.3, prepared using aluminum isopropoxide or boehmite as an aluminum source. Platinum (0.5 wt %) was deposited onto the molecular sieves prepared, and the catalytic properties of the resulting samples in n -hexadecane hydroisomerization were studied. The hydrocarbon conversion on these samples varies from 76.8 to 87.7 wt %, and the isoparaffin formation selectivity, from 76.7 to 91.2 wt %.

The fast catalytic pyrolysis of polystyrene in the hydrocarbon medium (light and heavy cycle oil) over zeolite catalysts at 450–550 °C was investigated. The influence of reaction conditions (medium, temperature, vapor residence time, polystyrene concentration) on polymer conversion and product distribution was studied. It was found that the polymer conversion is close to 100%, while ethylbenzene, benzene, and toluene are the main products of its transformation. The maximum yield of ethylbenzene (80%) was achieved at 550 °C, vapor residence time 1–2 s, polystyrene concentration 10%, and heavy cycle oil as the medium. The influence of zeolite topology on product distribution was explored. The possible mechanism of polystyrene pyrolysis was proposed.

This study investigated the activity of H-MFI catalysts modified by the top-down method in the liquid-phase Prins reaction between propene and formaldehyde. The physicochemical characterization of the catalyst demonstrated that grinding the catalyst reduces the specific surface area and affects the micropore to mesopore ratio in the samples. Reducing the grain size was found to increase the initial substrate consumption rate and reduce the diffusion limitations in the system. At the same time, grinding shifts the product composition towards a higher proportion of byproducts. An assessment of the kinetic curves enabled the researchers to propose a number of equations that accurately reflect catalyst deactivation. Both the reaction rate and deactivation rate vary directly with the zeolite dispersion, while the deactivation of the sample is more sensitive to the grain size.

The microstructure of low-molecular-mass ethylene–vinyl acetate copolymers was studied by 1 Н and 13 С NMR spectroscopy. The vinyl acetate mole fraction, chain branching, and mean lengths of ethylene and vinyl acetate blocks were determined. The thermal properties of ethylene–vinyl acetate copolymers were studied by differential scanning calorimetry and thermogravimetric analysis, and the crystalline characteristics, by X-ray diffraction analysis. The degree of crystallinity of the copolymer decreases with an increase in the fraction of the polar comonomer. Rheological studies show that ethylene–vinyl acetate copolymers at room temperature tend to microphase segregation and form a microphase structural network.

The relationships of the two-step regeneration of the slurry-phase hydroconversion catalyst separated as a component of a solid powder from the vacuum residue after distillation of the product obtained by hydroconversion of a mixture of petroleum tar and polymer waste were studied. The low-temperature oxidation of Mo sulfides was studied as the first step. High degree of oxidation of Mo sulfides to oxygen compounds of molybdenum in the highest oxidation state was reached at 250–400°С depending on the heat treatment time (from 30 to 150 min). The efficient oxidation is confirmed by the degree of transfer of the Mo oxides into an ammonia solution in the second step, leaching of the oxidation products obtained in the first step. The low-temperature oxidation of the catalyst concentrate as a component of the toluene-insoluble residue from the hydroconversion of a mixture of petroleum tar and polymer waste allows virtually complete (>95

This review provides an analysis of recent scientific and engineering literature on chemical methods for CO2 processing using heterogeneous catalysts. The following major uses of carbon dioxide are discussed: exhaustive hydrogenation; synthesis of hydrocarbons including light olefins; synthesis of oxygenates; and production of cyclic carbonates. Furthermore, the paper highlights the main design approaches for CO2 conversion catalysts and formulates priorities for decarbonization using heterogeneous catalytic reactions .

This study investigated the kinetic patterns of the liquid-phase Prins condensation of propylene with formaldehyde in the range of 120–180°C over H–MFI and H–BEA zeolites. The apparent reaction order with respect to formaldehyde was found to vary between 0.1 and 0.2 for H–BEA and to be close to zero for H–MFI. The apparent activation energy for H–MFI and H–BEA was 26.1±0.6 kJ/mol and 20.0±4.0 kJ/mol, respectively. Based on these results, the reaction was demonstrated to occur in the intradiffusion or transition region; the calculated Thiele modulus and effectiveness factor further confirmed this fact. The diffusion limitations were partially removed by raising the initial formaldehyde concentration, as indicated by an increase in the apparent order of formaldehyde conversion to 1.0 for H–BEA and to 0.4 in the H–MFI case. To describe the substrate transformations observed, a modernized reaction mechanism was proposed.

In this research the isotope labeling experiments were used to study the reaction pathways of acetone conversion in hydrocarbon medium in the presence Y and ZSM-5 zeolites. Acetone is a model for ketones, which are a considerable fraction of bio-oil. The analysis of the isotope distribution in the conversion products was carried out by H-1 NMR and GC/MS methods; it was shown that the deuterium labels introduced with acetone are distributed mainly in C-3-C-4 olefins, as well as pentenes and 2-methylpentane. The results obtained correspond with the previously proposed assumption that the catalytic cracking of ketones, capable to transform into enols, in a hydrocarbon medium starts with a nucleophilic attack of the protonated ketone on hydrocarbon intermediates. Additionally, the H/D exchange between deuterated compounds and cracking intermediates or zeolite has been established.

This review provides an analysis of recent publications focused on the promising methods for producing various valuable chemicals from acetylene. In particular, it discusses the main reactions of acetylene that produce large-tonnage, low-tonnage, and special-purpose chemicals. Furthermore, the paper highlights the most important approaches to the design of catalysts and formulates priority lines for the future development of acetylene chemistry.

The article discusses modern methods of stabilization and testing of the activity of cracking catalysts (FCC). Laboratory methods for evaluating cracking catalysts using fixed and fluidized bed reactors are compared, and their advantages and disadvantages are discussed. The correspondence of material balances of cracking was experimentally determined using various laboratory methods and a pilot plant with a riser reactor in comparison with data of industrial unit. Based on the analysis of the results obtained, recommendations are given for the most relevant testing of cracking catalysts.

The Prins reaction between propene and formaldehyde was studied over H-BEA, H-FAU, H-MFI and H-MOR zeolites at 150 °C in liquid phase. It was found that the H-BEA sample is the most active and selective toward buta-1,3-diene; the H-MFI is a potential catalyst for 3-buten-1-ol synthesis, while H-FAU can be used for 4-methyl-1,3-dioxane production. It had been confirmed that zeolite textural and acidic properties influence catalyst behaviour: the acidic properties influence sample activity, while product distribution is controlled by pore volume and effective pore diameter. The sample’s deactivation process had been studied and the kinetic model of deactivation was proposed. It was shown that the deactivation rate for the H-MFI catalyst is four times greater than for the H-BEA catalyst, probably because its strong/weak acid sites ratio is much more high than for the H-BEA.