Yield Of Target Product Research Articles

Multichannel microreactors for highly exothermic catalytic process: The influence of thermal conductivity of reactor material and of transport phenomena inside the channels on the process efficiency

In order to simulate strongly exothermic catalytic reactions in multichannel microreactors (MCMR), a new three-dimensional (3D) model is proposed. MCMR fabricated as brass disks 10 mm thick, with 250, or 500 parallel 1 mm channels are the subjects of experimental testing and modeling in the catalytic oxidation of methanol to formaldehyde. The 3D model incorporates two interconnected computational domains with the heat exchange between them, namely, the catalyst-filled channels and the metal disc. Axial effective conductivity and diffusivity in the channels, and intrinsic thermal conductivity of the metal disk are taken into account; the temperature of metal disk Tme is assumed variable. The new approach enabled to explore the influence of parameters on the process performance in various channels across the disk, which led to a correct prediction of the target product yield and of the critical temperature Tmax in the channels. Otherwise, the predicted yields and Tmax values would be overestimated or underestimated. The change in Tme as a result of the reaction heat generation dominates other factors that affect the establishment of Tmax. A generalized diagram provides permissible ranges for performing a strongly exothermic process in MCMR under constraints on the thermal stability of the catalyst, and relates the reaction heat generation to the appropriate intrinsic metal heat conductivity. The good agreement between simulated and observed results validates the approach and demonstrates the ability of the model to predict temperature, conversion and yield in each specific channel. Current study stimulates further use of the model for design and practical application of MCMR.

Определение термодинамических характеристик реакции получения N-метил-D-глюкозимина

The presented article is devoted to thermodynamic calculations of the N-methyl-D-glucosimine reversible formation reaction, an intermediate product for N-methyl-D-glucosamine synthesis, which is widely used in pharmaceutical practice as a ballast or counterion that improves the bioavailability of the main active substance. N-methyl-D-glucosimine is synthesized as a result of the interaction of D-glucose with methylamine in organic solvents, the reaction is reversible, and the yield of the target product depends entirely on the reaction conditions. The use of thermodynamic calculations makes it possible to evaluate the influence of the chemical process conditions on the yield of target products, which in turn contributes to a deeper understanding of the chemical reactions mechanisms. In chemical equilibrium, direct and reverse reactions proceed at equal rates, while the concentrations of products and reagents remain constant. When the reaction proceeds in a closed system, after a certain time, a state of equilibrium occurs, while the reaction does not proceed with a complete transformation of the reagents. This article presents the results of thermodynamic calculations of the reaction for the synthesis of N-methyl-D-glucosimine by the Van Kravlen – Cheremnov method. The Gibbs energy, equilibrium constants, and D-glucose conversion were calculated as activity function of reacting substances. It was shown that an increase in the temperature of the reaction mixture from 20 to 160 °C promotes an increase in the conversion of D-glucose from 3 to 32%, and therefore it is possible to recommend carrying out this reaction at elevated temperatures.

A Multicomponent Biocatalyzer for Use in Processing Plant-Based Raw Materials

Results from a study of the efficiency of Glucanofoetidine (a domestic enzyme preparation with a wide spectrum of action obtained at the Institute of Food Biotechnology) when applied to grain and fruit and berry raw materials show a 7‒18% increase in the yield of extractive substances (amino acids, sugars, phenolic compounds, carotenoids), including biologically active components (tocopherols, anthocyanins, vitamins), along with improved quality and a 10–44% increase in the yield of target products (juices and extracts). The practical importance of using Glucanofoetidine lies in the more rational use of plant raw materials than in the traditional technology with no enzymatic processing, and in the considerable shortening of the technological process (by half). The multienzyme composition of Glucanofoetidine determines the prospects for its use in the juice and fruit drink, confectionery, brewing, oil and fat, and bakery industries.

Preparation of Ti2AlC and Ti3AlC2 MAX Phases by Self-Propagating High-Temperature Synthesis with the Reduction Stage

This work is devoted to the preparation of powders of Ti2AlC and Ti3AlC2 MAX phases by self-propagating high-temperature synthesis (SHS) using the magnesium-thermal reduction from oxide feedstock. Oxide TiO2 is used as the titanium source, and magnesium is used as the reducing agent. Purification with the removal of magnesium oxide is performed in diluted hydrochloric acid at a temperature of 70°C and concentration of 1 : 3. The target product yield with the magnesium-thermal reduction is 35–40%. It is revealed that the synthesis product with the stoichiometric component ratio after chemical leaching in hydrochloric acid consists of Ti2AlC, MgAl2O4, and TiC. The formation of spinel MgAl2O4 is associated with the deficiency of the magnesium reducing agent in the charge; herewith, aluminum partially enters the reduction reaction of titanium from its oxide with the formation of Al2O3. This leads to the formation of spinel MgO ⋅ Al2O3. An increase in the content of excess magnesium in the charge from 20 to 30 wt % conditions the complete reduction of titanium from its oxide by magnesium with the formation of the Ti2AlC MAX phase and titanium carbide. A decrease of 10 wt % in the carbon content causes a decrease in the titanium carbide fraction to 4%. The product, containing Ti3AlC2 and Ti2AlC MAX phases, as well as TiC, is formed at an excess soot content from 20 to 35%, and the Ti3AlC2 weight fraction increases from 86 to 89%, respectively. These powders comprise agglomerates (87% of them are smaller than 65 μm) consisting of thin plates of MAX phases 70–100 nm in thickness.

Influence Different Methods of Mechanical Activation on Yield Extractive Substances from Pine Bark

The effect pine bark activation by explosive autohydrolysis and mechanical treatment in a ball mill on the yield and properties of resinous and pectin substances and β-sitosterol was studied. Pine bark physicochemical properties after its activation by a batch of methods were studied. It was shown that the activation of pine bark by explosive autohydrolysis result in the highest increase in the yield of extractive substances. The conditions providing the highest yield of target products from the activated pine bark were determined: for resinous substances and β-sitosterol – the use of 0.5 n alkali solution; for pectin substances – the use of hydrochloric acid

Co-Mg-Mn COMPOSITE CATALYSTS FOR PARTIAL OXIDATION OF NATURAL GAS

The problem of rational utilization of natural and associated petroleum gases and the cessation of their flaring is one of the acute and unresolved environmental problems. The aim of this work is to develop effective thermally stable catalysts of a new generation for the processes of oxidative conversion of light alkanes of natural and associated gas into synthesis gas. The results of partial oxidation of the methane of natural gas on the catalysts prepared by solution combustion synthesis are presented. Investigation of the activity of catalysts produced from initial mixture of Ni(NO3)2 - Al(NO3)3 - Mg(NO3)2 - Mn(NO3)2 + urea of different composition was carried out for the production of synthesis-gas. It was found that the optimal conditions for producing of synthesis-gas are: CH4 conversion higher than 95%, yield of target products: Н2 - 97 - 99% and СО - 40 - 43%, Т = 900оС, space velocity – 2500 and 6500 h-1. The catalysts were studied by X-ray diffraction, transmission electron microscopy, specific surface area, pore volume and average pore diameter. The presence in the catalysts of simple and mixed oxides, metal aluminates and spinel-type structures, the presence of which contributes to the active work of catalysts for oxidative conversion of CH4, has been established.

The Hydrolysis-Reduction of Arabinogalactan in the Presence of Ru/Cs3HSiW12O40 Catalyst

The hydrolysis-reduction of hemicellulose arabinogalactan to arabitol and galactitol polyalcohols, which are widely used in the food and pharmaceutical industries, was studied. It was shown that the process could be performed with the bifunctional catalyst containing highly dispersed ruthenium deposited on the cesium salt of silicon-tungsten heteropolyacid, Ru/Cs3HSiW12O40. The catalysts with different content of ruthenium (0.3, 0.6 and 1 wt.%) were synthesized for the study. The catalysts and their Cs3HSiW12O40 support were examined by various physicochemical methods (low-temperature nitrogen adsorption, IR spectroscopy, XRD, and TEM). The effect of temperature, substrate/catalyst ratio and ruthenium content in the catalyst on the yields of target products was elucidated. The highest yields of target products were achieved at the metal content of 0.6 wt.% and equal weights of the loaded catalyst and substrate (the 1:1 ratio). At a temperature of 200 °C, arabitol and galactitol can be produced with the yields up to 12 and 48 % for 2 h of the reaction in the presence of catalyst with the composition 0.6%Ru/Cs3HSiW12O40.

Lovastatin Production from Aspergillus Terreus ATCC 20542 Under Various Vegetable Oils Used as Sole and Supplementary Carbon Sources

The effect of vegetable oils used as sole and supplementary carbon sources on the production of lovastatin by Aspergillus terreus ATCC 20542 and their biomass in submerged fermentation has been examined. Eleven different types of edible vegetable oils were tested including camellia tea oil, canola oil, coconut oil, corn oil, olive oil, palm olein oil, rice bean oil, safflower oil, sesame oil, soybean oil, and sunflower oil. All selected oils can improve the yield of target product at least 2 times. The maximum yield was 87.18 g/L with supplementary 1% w/v coconut oil, which was about 11 times higher than that obtained from the oil-free control. Fungal biomass was proportional to vegetable oil concentration, but an excessive concentration of oil resulted in a lower yield. Substitutions of coconut oil and soybean oil at any quantities for lactose used as sole carbon source showed very low concentrations of lovastatin. These findings indicate that vegetable oils can be used for supporting fungal growth more than the secondary metabolite production. It can be concluded that easily available vegetable oil is a very promising adjuvant for lovastatin production.

The Effect of Hexene-1 in Feedstock on the Yield of Target Products during Thermal Pyrolysis of n-Hexane

The effect of the α-olefin addition in the pyrolysis feedstock on the yield of ethylene, propylene, and divinyl (butadiene-1,3) was studied using the n-hexane–hexene-1 model system under conditions of a laboratory flow-type thermal pyrolysis setup. It was found that the total yield of unsaturated hydrocarbons C2=–C4= depends on the ratio of n-hexane : hexene-1 in the initial mixture and is characterized by a maximum value at a 0.36 molar fraction of hexene-1 in feedstock. The main directions of reactions in the presence of an α-olefin are discussed.

Production of Cast Materials Based on the Cr2AlC MAX Phase by SHS Metallurgy Using Coupled Chemical Reactions

It is known that materials based on MAX phases possess a large potential for use in aerospace, automobile, and industrial spheres because they have a unique combination of features of both metals and ceramics with high mechanical, chemical, thermal, and electrical properties. In this work, the experimental results of fabricating cast materials in the Cr–Al–C system with different ratios between the Cr2AlC MAX phase and chromium aluminides and carbides by SHS metallurgy are presented. The experiments were performed in an SHS reactor 3 L in volume at an initial inert gas (argon) pressure of 5 MPa. The synthesis was performed based on chemically coupled reactions: weakly exothermic (heat acceptor)—Cr2O3/3Al/C and strongly exothermic (heat donor)—3CaO2/2Al. The experimental results have good correlation with the preliminary thermodynamic calculations. It is shown that, when varying the composition of initial mixtures, it is possible to substantially affect the calculated and experimental synthesis parameters, as well as the phase composition and microstructure of final products. Optimal synthesis conditions of the material providing the maximal yield of the Cr2AlC phase in the ingot composition are established. The determining factor affecting the Cr2AlC content in the product is the occurrence time of the liquid phase under the synthesis conditions. It is shown that the maximal content of the Cr2AlC MAX phase and target product yield are attained at the 30% content of the strongly exothermic additive (3CaO2/2Al) in the initial charge.

Solvent-Free Self-Assembly for Scalable Preparation of Highly Crystalline Mesoporous Metal Oxides.

Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic-organic self-assembly process. Here, we develop a facile, general, and high throughput solvent-free self-assembly strategy to synthesize a series of MMOs including single-component MMOs and multi-component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self-assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications.

Solvent‐Free Self‐Assembly for Scalable Preparation of Highly Crystalline Mesoporous Metal Oxides

AbstractMesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic‐organic self‐assembly process. Here, we develop a facile, general, and high throughput solvent‐free self‐assembly strategy to synthesize a series of MMOs including single‐component MMOs and multi‐component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self‐assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications.

Improved ethane conversion to ethylene and aromatics over a Zn/ZSM-5 and CaMnO3-δ composite catalyst

Abstract Ethane conversion to ethylene and aromatics over Zn/zeolite catalysts is a promising technology for efficient exploitation of light alkanes. However, the reaction faces two major hurdles including the limited ethane conversion due to thermodynamics and the drastic catalyst deactivation by kinetical coke accumulation. Here we present a route to improve ethane conversion using a composite catalyst, involving Zn/HZSM-5 for ethane dehydroaromatization and CaMnO3-δ perovskite for in situ selective hydrogen oxidation. The in situ H2 consumption shifts ethane dehydrogenation equilibrium to the desired side and can obviously increase the yield of target product. Furthermore, it is found that the in situ generated H2O through H2 combustion can significantly suppress the coke formation and consequently enhance the stability of the composite catalyst. After 400 min reaction, a product yield of 23% was retained over the composite catalyst, almost a threefold increase with respect to the Zn/HZSM-5 reference (8%). It is anticipated that this novel composite catalyst combined with an efficient reactor technology may improve the viability of ethane aromatization in utilization.

Improved Synthesis of Sulfur-Containing Glycosides by Suppressing Thioacetyl Migration.

Complex mixtures were often observed when we attempted to synthesize 4-thio- and 2,4-dithio-glycoside derivatives by double parallel and double serial inversion, thus leading to no or low yields of target products. The reason was later found to be that many unexpected side products were produced when a nucleophile substituted the leaving group on the substrate containing the thioacetate group. We hypothesized that thioacetyl migration is prone to occur due to the labile thioacetate group even under weak basic conditions caused by the nucleophile, leading to this result. Therefore, we managed to inhibit the generation of thiol groups from thioacetate groups by the addition of an appropriate amount of conjugate acid/anhydride, successfully improving the synthesis of 4-thio- and 2,4-dithio-glycoside derivatives. The target products which were previously difficult to synthesize, were herein obtained in relatively high yields. Finally, 4-deoxy- and 2,4-dideoxy-glycoside derivatives were efficiently synthesized through the removal of thioacetate groups under UV light, starting from 4-thio- and 2,4-dithio-glycoside derivatives.

Synthesis of Novel Furo[3,2‐c]coumarin Derivatives through Multicomponent [4+1] Cycloaddition Reaction Using ZnO/FAp as a Sustainable Catalyst

AbstractAn efficient green protocol is developed for the synthesis of ten new furo[3,2‐c]coumarin derivatives employing zinc oxide loaded on fluorapatite (ZnO/FAp) as catalyst. The three‐component one‐pot condensation occurs between the 4‐hydroxycoumarin, isocyanide and selected aldehyde in ethanol solvent at room temperature. Excellent yields (94‐98 %) of target products in 16‐20 min reaction time is the attractive feature. As‐synthesized catalysts and organic compounds were fully established by powder‐XRD, TEM, SEM, EDX, FT‐IR, BET, HRMS, 1H NMR and 13C NMR analysis. The catalyst is recyclable up to five times with high efficacy and marginal loss of activity. The reaction facilitated 98 % of the atom economy and 100 % carbon efficiency. Other advantages of the protocol are mild reaction conditions, easy‐workup, green solvent, catalyst reusability, and chromatography free products.

Selection of the most beneficial raw materials for the synthesis of biodiesel from a standpoint of its yield and physicochemical properties

Biodiesel presents itself as one of the most promising alternative energy sources at the present time, both as a pure fuel and a mixed component of petroleum-based diesel fuels. According to research works carried out around the world, the addition of biodiesel to diesel oil is established to significantly improve the environmental friendliness of this oil product. Nevertheless, its effect on most regulated operational indicators remains ambiguous due to the characteristics of biodiesel fuel varying greatly depending on the feed-stock. The present paper is aimed at resolving the issue of selecting the most beneficial raw material for the synthesis of biodiesel from the perspective of the target product yield, physicochemical and low temperature characteristics. In this study, biodiesel was synthesised from five different edible vegetable oils (sunflower, mustard, linseed, corn and camelina) using ethanol and potassium hydroxide as transesterifying agent and catalyst, respectively. The main physicochemical (density, dynamic and kinematic viscosity, molecular weight) and low-temperature (cloud point and pour point) properties of vegetable oils, as well as biodiesel fuels derived therefrom, are determined. According to the obtained yield values of the target product, sunflower oil is shown to be the optimal raw material for the synthesis of biodiesel. From the position of their physical and chemical properties, sunflower and corn oil appear to equally preferential, while, with regard to low temperature properties, mustard oil turns out to be the optimal feedstock. Sunflower oil was additionally determined to be a leader in terms of economics. The paper presents recommendations for choosing the most preferable raw materials for the synthesis of biodiesel, which are useful in application of biodiesel as a mixed component for commercial diesel fuels.

Automatic Redirection of Carbon Flux between Glycolysis and Pentose Phosphate Pathway Using an Oxygen-Responsive Metabolic Switch in Corynebacterium glutamicum.

Controlling the carbon flux into a desired pathway is important for improving product yield in metabolic engineering. After entering a cell, glucose is channeled into glycolysis and the pentose phosphate pathway (PPP), which decreases the yield of target products whose synthesis relies on NADPH as a cofactor. Here, we demonstrate redirection of carbon flux into PPP under aerobic conditions in Corynebacterium glutamicum, achieved by replacing the promoter of glucose 6-phosphate isomerase gene (pgi) with an anaerobic-specific promoter of the lactate dehydrogenase gene (ldhA). The promoter replacement increased the split ratio of carbon flux into PPP from 39 to 83% under aerobic conditions. The titer, yield, and production rate of 1,5-diaminopentane, whose synthesis requires NADPH as a cofactor, were increased by 4.6-, 4.4-, and 2.6-fold, respectively. This is the largest improvement in the production of 1,5-diaminopentane or its precursor, lysine, reported to date. After aerobic cell growth, pgi expression was automatically induced under anaerobic conditions, altering the carbon flux from PPP to glycolysis, to produce succinate in a single metabolically engineered strain. Such an automatic redirection of metabolic pathway using an oxygen-responsive switch enables two-stage fermentation for efficient production of two different compounds by a single strain, potentially reducing the production costs and time for practical applications.

A multicomponent biocatalyst for vegetable feedstock processing

he improvement of technologies for the production of foodstuffs and dietary supplements from vegetable feedstock using natural and efficient biocatalytic systems is a promising direction in the development of agroindustrial complex. At present, enzyme preparations produced in Russia are virtually absent at the market; therewith, high cost of their imported analogs increases the prime cost of products. A study on efficiency of the domestic broad-spectrum enzyme preparation Glucanofoetidin, which was developed at the Russian Scientific Research Institute of Food Biotechnology, toward fruit and berry feedstock and corn showed an increase in the yield of extractive substances (amino acids, sugars, phenol compounds, and carotenoids), particularly the biologically active components (tocopherols, anthocyanins, and vitamins), by 7–18 % as well as the quality improvement and an increase in the yield of target products (juices and extracts) by 10–44 %. Practical importance of Glucanofoetidin consists in a more rational use of vegetable feedstock as compared to conventional technology without enzymatic treatment, and also in a considerable (twofold) shortening of the process time. The multienzyme composition of Glucanofoetidin makes it promising for use in juice, confectionary, brewing, oil-and-fat and baking industries.

The rate-limiting step in the integrated coal tar decomposition and upgrading- iron ore reduction reaction determined by kinetic analysis

Simultaneously achieving high-quality catalytic cracking of light tar, maintaining a large target product yield and improving the reductivity of iron ore, is major step towards enhancing the energy conversion efficiency of the coal chemical industry and ironmaking applications. To achieve the aforementioned goals, an experiment involving regulation under coal pyrolysis, with iron ore as a catalytic bed, optimization of carbon deposition in spent samples and integration of multiple similar reaction factors between the pyrolysis of experimental samples and volatile decomposition-carbon deposition was designed. The mass fraction and yield of the light tar produced when the pyrolysis tar is passed through a goethite bed are 75.1 % and 5.34 % at the upper reactor temperature of 550 °C, respectively, which are higher than those of the other two iron ore. Additionally, because the iron ore contains carbon deposits at the nanometre scale, compared with the original iron ore, the spent sample exhibits a peculiar phenomenon in which the reactivity increases. The reduction degree, metallization ratio of the iron ore and kinetic characteristics are compared and analysed, confirming a response mechanism to enhance the reduction degree on various fluctuating factors at temperatures exceeding 800 °C, and revealing that the reduction reaction occurs consecutively in four consecutive according to the efficiency of the conversion. In absence of sufficient CO2 in the reaction and according to the calculated activation energy, the carbon gasification reaction was identified as a rate-limiting step in the reduction reaction. The activation energy and rate-limiting step provide a pathway featuring pollution reduction, clean energy and energy conservation aimed towards the deployment of integrated technology for tar upgrading and iron ore reduction.

N-Alkylation Reaction in the Synthesis of Tetra-Substituted Glycoluryls

A new method is suggested herein for the synthesis of tetrasubstituted glycolurils by treatment of disubstituted glycolurils (di-tert-butylglycolurils, di-isopropylglycoluril) with alkylating agents such as methyl iodide, ethyl bromide and benzyl chloride in acetonitrile in the presence of KOH. Optimum conditions for the preparation of the target product in high yield were studied by the example of the synthesis of dibenzyl-di-tert-butylglycoluril: time 3 h and reaction temperature 75ºС at a 1:4 M/M molar ratio of disubstituted glycoluril to benzyl chloride. Thus, the target product yield was 83%. It was also found that benzyl chloride should be used as the alkylating agent because the product yield under the same equal conditions was higher with benzyl chloride than with benzyl bromide which in turn is more toxic and less available