Catalysis in Industry最新文献

Catalysts of the second stage of hydrocracking are tested under different conditions, reducing the time required to reach the level of steady-state activity. Tests are performed on a laboratory testbench under conditions (temperature, pressure, and liquid hourly space velocity (LHSV)) close to industrial and typical of the second stage of hydrocracking. Introducing an additional preliminary stage at the start of tests at elevated temperatures and LHSVs while using a dimethyl disulfide solution in decane as a sulfiding mixture are shown to substantially reduce the time of experiment. Conditions of the preliminary stage that preserve the catalyst’s selectivity to diesel are selected.

To develop Ru-incorporated bentonite clay as a heterogeneous base catalyst for use in Knoevenagel condensation as an alternative to hazardous base catalysts like pyridine, piperidine, etc., we purify the naturally occurring bentonite clay and Ru³⁺ cation incorporated into its interlayers of bentonite clayto improve its porosity and to increase the surface area of bentonite clay. Purified bentonite and Ru-bentonite were characterized by FTIR, PXRD, HRTEM, SEM & EDS, BET surface area analysis, and TGA. Base activation was done to these clays and a comparative study of these clays as recyclable heterogeneous catalysts for Knoevenagel Condensation was undertaken in water as a solvent for the chemical transformation of 2,4-dichlorobenzaldehyde and 4-hydroxybenzaldehyde with ethyl cyanoacetateinto their corresponding α,β- unsaturated acids. The products were characterized by FTIR, ¹H NMR, and ¹³C NMR analyses. The essential key points of this reaction are mild reaction conditions, absence of hazardous chemicals as used in classical Knoevenagel condensation, reusability of the catalyst, and high yield percentage of the products.

The study is focused on the catalytic pyrolysis of high density polyethylene (PE) in the presence of HBEA, HZSM-5, and HFER catalysts and natural clay. The catalytic pyrolysis of plastics is a promising method to process recyclable materials, because it provides the conversion of polymers to other compounds, which are subsequently used as reagents for the chemical industry. The physicochemical parameters of the catalysts have been determined by Fourier transform IR spectroscopy, X-ray diffraction analysis, the nitrogen physical adsorption method, thermogravimetric analysis, and pyrolytic gas chromatography. The dependences of the PE degradation temperatures and the chemical composition of the catalytic pyrolysis products on the type of catalyst used have been revealed. The efficiency of the cracking process and the qualitative composition of the products are affected by two main factors: the structural and acidic parameters of the catalyst. The presence of Brønsted acid sites in zeolites contributes to the occurrence of the cracking and aromatization reactions. The possibility of using a clay sample for the thermal degradation of PE has been studied.

The properties of supported Pt-containing granular (Pt/Ce_0.75Zr_0.25O_{2 – δ}) and structured catalysts (Pt/Ce_0.75Zr_0.25O_{2 – δ}/η-Al₂O₃/FeCrAl) in methanol decomposition to synthesis gas for feeding solid oxide fuel cells have been studied. It has been shown that the use of a structured catalyst for the methanol decomposition reaction is promising. It has been found that the addition of a small amount of oxygen to the feed mixture hinders the formation of carbon and thereby increases the on-stream stability of the catalyst. At atmospheric pressure, a temperature of ≈400°C, a reaction mixture feed space velocity of 5.6 L/(g_cat h), and a CH₃OH : air volume ratio of 1, the proposed 0.15 wt % Pt/8 wt % Ce_0.75Zr_0.25O_{2 – δ}/6 wt % η-Al₂O₃/FeCrAl structured catalyst can provide a complete methanol conversion to synthesis gas with a total content of H₂ and CO of ≈64 vol % and a productivity with respect to synthesis gas of ≈6.7 L(H₂ + CO)/(g_cat h).

The synthesis of esters by the alkoxycarbonylation of unsaturated substrates of plant origin opens up the possibility of switching to alternative raw materials and provides a solution to a number of problems facing the chemical industry: resource saving, waste minimization, and increasing the environmental safety and efficiency of the processes being implemented. However, to date, only the production of methyl methacrylate, which includes ethylene methoxycarbonylation as one of the stages, has been implemented in industry. The aim of this review is to systematize and analyze the data published since 2010 in the field of ester synthesis by the alkoxycarbonylation of plant substrates under mild conditions. It has been found that, over the indicated period, the alkoxycarbonylation of pentenoic and undecenoic acids, oleic, linoleic, and erucic acids or their esters, and terpene compounds—citronellic acid and β-myrcene—has been implemented. It has been shown that high yields of linear products and selectivities for them under mild conditions have been provided mostly by using homogeneous palladium–diphosphine catalysts. The results of these studies open up broad prospects for the implementation of processes that are new for industry, namely, the alkoxycarbonylation of substrates of plant origin for synthesizing chemical products of high priority, primarily polymers.

Experience in the industrial use of the technology of synthetic hydrocarbons at the Novocherkassk Plant of Synthetic Products (NPSP) (Novocherkassk, Rostov region) has been summarized. More than 200 types of commercial products for general consumption were produced at NPSP. The article presents information on the production of syngas from natural gas, on the synthesis of hydrocarbons, and process catalysts.

The results of using capillary chromatographic columns with different stationary phases were compared to determine the purity of isopropanol obtained by hydrogenation of acetone. The study was performed with columns based on 2-nitroterephthalic acid-modified polyethylene glycol 20М (PEG20М/FFAP), poly(1-trimethylsilyl-1-propyne) (PTMSP032), and trifluoropropyl (25%) methyl silicone elastomer (SKTFT 50Х). The measurement times, asymmetry factors (A_s) of mixture components, and resolutions (R_s) of the acetone/isopropanol and isopropanol/internal standard pairs of compounds were compared; as a result, the PEG20М/FFAP capillary column was chosen. A technique for measuring the mass fractions of acetone and isopropanol using the internal standard method in the gas phase has been developed. n-Butanol was used as an internal standard. The detection limit was 1.45 for acetone, 1.43 for isopropanol, and 1.28 × 10^–12 g/s for n-butanol. The relative standard deviation (repeability factor) did not exceed 4.3% at a confidence level Р = 0.95.

Two samples of TiO₂/Cr₂O₃ composites are synthesized in the form of spherical grains via the stagewise thermal treatment of ion-exchange resins preliminarily saturated with chromium Cr³⁺ cations and dichromate ({text{C}}{{{text{r}}}_{{text{2}}}}{text{O}}_{7}^{{2 - }}) anions, and then coated with a film-forming titania-based solution. Calcination temperature regimes are set on the basis of a thermal analysis and determined by the type of ion-exchange resin selected as a template. The synthesized composites are generally composed of the α-Cr₂O₃ phase, and the content of the TiO₂ phase is less than 4%. The composites replicate the spherical shape of grains for the initial ion-exchange resins with sizes of 370 to 660 µm. The grains of the sample based on kaolinite adsorbing Cr³⁺ ions have a porous structure with bulbs and cavities. The anion-exchange resin-based sample grains have kinks and cracks over their surfaces due to a nonuniform distribution of adsorbed ({text{C}}{{{text{r}}}_{{text{2}}}}{text{O}}_{7}^{{2 - }}) anions in the initial anion-exchange resin. The composites exhibit catalytic activity in the deep p-xylene oxidation reaction. The cation-exchange resin-based sample is more active, due apparently to the smaller accessible titania surfaces in the anion-exchange resin-based sample as a result of the formation of a solid Ti³⁺ solution in α-Cr₂O₃.

The concepts of the effect of the adsorption of the reaction medium components on the selective hydrogenation of acetylene to ethylene under the action of supported palladium catalysts have been discussed. The role of interstitial solid solutions of carbon and hydrogen in palladium, which are formed upon contact of the catalyst with the reaction medium, in the occurrence of mass transfer processes between the surface and the subsurface layer of the active component has been shown. The ratio of activation barriers to ethylene desorption/adsorption processes, which determines the acetylene hydrogenation selectivity, can vary depending on the structure of palladium nanoparticles and the electronic state of Pd. In addition, changes in the electronic state affect the energy of the activated desorption of ethylene from palladium particles, and their structural features determine the energy of the activated adsorption and subsequent hydrogenation of ethylene to ethane.

Solid-phase synthesis of aluminum–molybdenum (Al–Mo) and aluminum–nickel–molybdenum (Al–Ni–Mo) model composites as part of propylene metathesis catalysts has been conducted under mechanical activation. The structure of Al–Mo and Al–Ni–Mo model composites has been studied by X-ray diffraction analysis, high-resolution transmission electron microscopy, infrared spectroscopy, and diffuse reflectance electron spectroscopy (DRES). The DRES method has shown the presence of isolated monomeric and oligomeric molybdate compounds in the Al–Ni–Mo model composites. Granular metathesis catalysts have been synthesized by molding the Al–Mo and Al–Ni–Mo model composites with aluminum hydroxide and subsequent calcining. It has been shown that the highest activity in the propylene metathesis reaction is exhibited by an aluminum–molybdenum catalyst containing 2.6 wt % Ni, 13.0 wt % Mo, and 32.7 wt % Al. At a process temperature of 200°C, a pressure of 0.1 MPa, and a propylene feed space velocity of 1 h^–1, in the presence of this catalyst, the propylene conversion achieves 33.7%; this fact makes this catalyst promising for practical applications. At the same time, the weight fraction of ethylene and butenes in the reaction product composition is 17.5 and 71.3%, respectively.