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Background: 2-O-α-D-glucosyl glycerol (2-αGG) is a valuable ingredient in cosmetics, health-care and food fields. Sucrose phosphorylase (SPase) is a favorable choice for biosynthesis of 2-αGG, while its glucosyl-acceptor affinity and thermodynamic feature remain largely unknown, limiting 2-αGG manufacturing. Results: Here, three SPases were obtained from lactobacilli and bifidobacteria, and the one encoded by Lb. reuteri SDMCC050455 (LrSP) had the best transglucosylation ability, with 2-αGG accounting for 86.01% in the total product. However, the LrSP exhibited an initial forward reaction rate of 11.83/s and reached equilibrium of 56.90% at 110 h, indicating low glycerol affinity and conversion rate. To improve catalytic efficiency, the LrSP was overexpressed in Lb. paracasei BL-SP, of which the intracellular SPase activity increased by 6.67-fold compared with Lb. reuteri SDMCC050455. After chemically permeabilized with Triton X-100, the whole-cell biocatalysis of Lb. paracasei BL-SP was prepared and showed the highest activity, with the initial forward reaction rate improved to 50.17/s and conversion rate risen to 80.79% within 17 h. Using the whole-cell biocatalyst, the final yield of 2-αGG was 203.21 g/L from 1 M sucrose and 1 M glycerol. Conclusion: The food grade strain Lb. paracasei was used for the first time as cell factory to recombinantly express the LrSP and construct a whole-cell biocatalyst for the production of 2-αGG. After condition optimization and cell permeabilization, the whole-cell biocatalyst exhibited 23.89% higher equilibrium conversion and 9.10-fold of productivity compared with the pure enzyme catalytic system. This work would provide a reference for large-scale bioprocess of 2-αGG. [ABSTRACT FROM AUTHOR]

In the preparation of polyammonium resin by polycondensation of equimolar amounts of epichlorohydrin and 1,3-bis(dimethylamino)propanol-2 in aqueous solutions, a nonstandard concentration effect was revealed, which manifested itself in a sharp increase in the reduced reaction rate, equilibrium conversion, and achievable molecular weight of the polymer at initial concentrations of reagents close to 2.0 mmol/g (the concentration range of 0.5–3.5 mmol/g was studied). The data obtained can be used in the search for additional economical resources to improve the technical and economic indicators of organic synthesis processes. [ABSTRACT FROM AUTHOR]

To overcome the low equilibrium conversion in the direct synthesis of diethyl carbonate from ethanol and CO2 under moderate reaction conditions, the reaction was conducted in a membrane reactor packed with pelletized Cu‐Ni:3‐1 supported on activated carbon. A SiO2/γ‐Al2O3 commercial membrane and zeolite A membranes synthesized on commercial Al2O3 supports were evaluated in the membrane reactor. Although characterization of the membranes by X‐ray diffraction confirmed the presence of a zeolite A layer on the supports, gas permeation and permselectivity tests of ethanol and water evidenced some defects of the synthesized membranes. An increase in conversion with respect to a conventional packed‐bed reactor was observed in the membrane reactors prepared on Al2O3, but equilibrium conversion was not attained. However, with the commercial membrane, the ethanol conversion was higher than the equilibrium conversion. [ABSTRACT FROM AUTHOR]

In the nucleophilic addition of N-(3-dimethylaminopropyl)methacrylamide to acrylic acid (1 : 1) in aqueous solutions, forming monomeric β-propiobetaine, the dependence of the initial rate on the starting reagent concentration was found to have a pronounced maximum (whose position does not depend on the temperature at 30-70°С). In the case of the addition of N, N-dimethylaminoethyl methacrylate, the dependence was exponential. The dependences of equilibrium conversions on the starting reagent concentrations were of the same type and had a maximum for both systems. The detected concentration effects are related to the peculiarities of the pre-reaction association of the reagents. [ABSTRACT FROM AUTHOR]

A prospective study on the product distribution at chemical equilibrium for the simultaneous liquid-phase etherification of isobutene and isoamylenes with ethanol over Amberlyst™ 35 is presented. Experiments were performed isothermally in a 200 cm 3 stirred tank batch reactor operating at 2.0 MPa. Initial molar ratios of alcohol/olefins and isobutene/isoamylenes ranged both from 0.5 to 2, and temperature from 323 to 353 K. Reactants equilibrium conversion, selectivities and yields toward products were clearly affected by the experimental conditions. Experimental etherification yields have been modeled using the response surface methodology (RSM), combined with the stepwise regression method to include only the statistically significant variables into the model. The multiobjective optimization (MOO) of etherification yields has been carried out numerically, by means of the desirability function approach, and graphically, by using the overlaid contour plots (OCP). Optimal conditions for the simultaneous production of ethyl tert -butyl ether (ETBE) and tert -amyl ethyl ether (TAEE) have been found to be at low temperatures (323 to 337 K) and initial molar ratio alcohol/olefins close to 0.9 and isobutene/isoamylenes close to 0.5. [ABSTRACT FROM AUTHOR]

An in situ bimolecular reaction, in which syngas is fed with toluene as a secondary reactant (hereafter Tol in situ methylation), was studied over bifunctional catalysts comprised of methanol synthesis catalyst and H-ZSM-5 in a fixed-bed down-flow reactor at 460 psig. When physically mixed with H-ZSM-5 to form bifunctional catalysts, CrZ_HZ (CrO/ZnO + HZSM-5) catalyst showed much higher activity than CZA_HZ (CuO/ZnO/AlO + H-ZSM-5) in the Tol in situ methylation, while CrZ catalyst exhibited substantially lower activity than CZA in methanol synthesis. CO conversion to methanol in the Tol in situ methylation was estimated by Bz in situ methylation. The CO conversion to methanol was calculated to be in the range of 11-27 %, while that in methanol synthesis over CrZ was about 5 % at most due to chemical equilibrium limitation. By employing a silicalite-coated H-ZSM-5 (Sil/HZ) in bifunctional catalyst, xylene selectivity and para-xylene yield were much improved in the Tol in situ methylation. [ABSTRACT FROM AUTHOR]

Equilibrium conditions of the main reactions of the SI cycle were studied in this paper. The extent of reaction for two main reactions of this cycle including sulfuric acid decomposition and hydrogen iodide decomposition was evaluated as a function of temperature, pressure, and initial mole number of reactants. In the reaction modelling of sulfuric acid and sulfur trioxide decompositions, two models including simple and multiple reaction models were considered. In the simple model, it was assumed that two decomposition reactions proceeded independently. However, in the multiple reaction model, both reactions were considered simultamneously. It was shown that the Bunsen reaction completely proceeded in the range of operating conditions of the Bunsen reactor. Also, sulfuric acid was demonstrated to be decomposed at a higher rate when the reaction temperature and initial concentration of the sulfuric acid and sulfur trioxide increased. Furthermore, the operating pressure had to be maintained at lower values and the generated sulfur dioxide had to be withdrawn from the reactor in order to have a higher yield of product in this reactor. Finally, in the hydrogen iodide decomposition, the operating pressure, temperature, and concentration of hydrogen iodide had to be maintained at higher values to have a complete reaction. Moreover, the generated hydrogen was shown to be withdrawn from the hydrogen iodide reactor to prevent from backward reaction. [ABSTRACT FROM AUTHOR]

Hydrogenation of CO to hydrocarbons over iron nanoparticles supported on oxygen-functionalized multi-walled carbon nanotubes was studied in a fixed-bed U-tube reactor at 25 bar with a H:CO ratio of 3. Conversion of CO was approximately 35% yielding C-C products at 360 C with methane and CO as major products. The CO equilibrium conversion for temperatures in the range of 320 to 420C was analysed by using CHEMCAD simulation software. Comparison between experimental and simulated degrees of CO conversion shows that reverse water gas shift equilibrium had been achieved in the investigated temperature range and that less than 47% of CO can be converted to CO at 420C. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a study of glycerol etherification with tert-butyl alcohol catalyzed by Amberlyst 15 in reactive distillation (RD). A thermodynamic analysis is firstly investigated by applying three group contribution methods, to determine the equilibrium composition by minimization of the Gibbs free energy and to compare the predicted values against measured data. Next, the kinetic model parameters are regressed by matching measured data from an autoclave reactor. The activity based Langmuir–Hinshelwood model is found to give the best representation of the reaction rate data. The regressed kinetic rate expressions are also compared against independently measured data in fixed bed reactors reported in the literature and found to give a good match. Finally, using the developed models, it is shown by simulation as well as verification by experiments, that the suitable RD configuration for the production of glycerol ethers in RD is the one consisting of 6 rectifying stages and 6 reaction stages without stripping stage. [Copyright &y& Elsevier]

The thermodynamics involved in the catalytic hydrogenation of CO2 have been examined extensively. By assuming that methanol and dimethyl ether (DME) are the main products, two reaction systems each consisting of two pararell reactions were analyzed and compared in terms of the equilibrium yield and selectivity of the useful products, methanol and DME. The calculation results demonstrated that the production of DME allows much higher oxygenate yield and selectivity than that of methanol. [ABSTRACT FROM AUTHOR]