Suchergebnisse

Supercritical carbon dioxide (SC-CO2) has been used as green solvent in the lipase-catalyzed ethanolysis of fish oil by Lipozyme RM IM at mild, non-oxidative conditions and with no solvent residues. The effect of experimental conditions, initial substrate ethanol/oil molar ratio (2–38), pressure (7.5–30 MPa), and temperature (323.15–353.15 K) on equilibrium conversion, reaction rate and oxidative status of the products has been studied. No ethanol inhibition has been observed at high concentrations of ethanol, when putting in contact first the fish oil with the enzyme avoiding direct contact between the biocatalyst and ethanol. Operating pressure affected positively the reaction performance in the range investigated. Visual observation of the phase behaviour of the initial reaction mixture showed an "expanded liquid phase" that helped enhancing reaction rate, and a gas phase. Raising temperature accelerated the reaction up to a limit (343.15 K), observing higher enzyme thermal stability than in other reaction media (313.15 K). However, lipid oxidation increases with temperature. Up to 86 ± 1% FAEE yield has been found at MR = 6:1, 30 MPa and 323.15 K. Kinetic data have been correlated by using a mathematical model based on the elementary reactions of the 3-step transesterification. Kinetic rate constants, apparent activation volumes and energies are reported for the first time for a lipase-catalyzed ethanolysis reaction in SC-CO2. ; Spanish Government (MINECO) and the European Regional Development Fund (ERDF) for financial support of the project CTQ2012-39131-C02-01. Financial support from the Junta de Castilla y León and European Regional Development Fund (ERDF) through project BU055U16

[EN] Due to the heterogeneity of oils, the use of mixtures of lipases with di erent activity for a large number of glycerol-linked carboxylic acids that compose the substrate has been proposed as a better alternative than the use of one specific lipase preparation in the enzymatic synthesis of biodiesel. In this work, mixtures of lipases from di erent sources were evaluated in their soluble form in the ethanolysis of soybean oil. A mixture of lipases (50% of each lipase, in activity basis) from porcine pancreas (PPL) and Thermomyces lanuginosus lipase (TLL) gave the highest fatty acid ethyl ester (FAEE) yield (around 20 wt.%), while the individual lipases gave FAEE yields 100 and 5 times lower, respectively. These lipases were immobilized individually by the cross-linked enzyme aggregates (CLEAs) technique, yielding biocatalysts with 89 and 119% of expressed activity, respectively. A mixture of these CLEAs (also 50% of each lipase, in activity basis) gave 90.4 wt.% FAEE yield, while using separately CLEAs of PPL and TLL, the FAEE yields were 84.7 and 75.6 wt.%, respectively, under the same reaction conditions. The mixture of CLEAs could be reused (five cycles of 6 h) in the ethanolysis of soybean oil in a vortex flow-type reactor yielding an FAEE yield higher than 80% of that of the first batch. ; This work was supported by the São Paulo Research Foundation (FAPESP) (grant numbers #2011/23194-0 and #2016/10636-8), Conselho Nacional Desenvolvimento Científico e Tecnológico (CNPq, grant numbers #405889/2016-0, #308212/2017-7), in part by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001, and the MICIU of Spanish Government (project CTQ2017-86170-R). ; Peer reviewed

© 2020 by the authors. ; Eversa® Transform 2.0 has been launched to be used in free form, but its immobilization may improve its performance. This work aimed to optimize the immobilization of Eversa® Transform 2.0 by the crosslinked enzyme aggregates (CLEAs) technique, using almost all the available tools to improve its performance. Several variables in the CLEA preparation were optimized to improve the recovered activity, such as precipitant nature and crosslinker concentration. Moreover, some feeders were co-precipitated to improve the crosslinking step, such as bovine serum albumin, soy protein, or polyethyleneimine. Starch (later enzymatically degraded) was utilized as a porogenic agent to decrease the substrate diffusion limitations. Silica magnetic nanoparticles were also utilized to simplify the CLEA handling, but it was found that a large percentage of the Eversa activity could be immobilized on these nanoparticles before aggregation. The best CLEA protocol gave a 98.9% immobilization yield and 30.1% recovered activity, exhibited a porous structure, and an excellent performance in the transesterification of soybean oil with ethanol: 89.8 wt% of fatty acid ethyl esters (FAEEs) yield after 12 h of reaction, while the free enzyme required a 48 h reaction to give the same yield. A caustic polishing step of the product yielded a biodiesel containing 98.9 wt% of FAEEs and a free fatty acids content lower than 0.25%, thus the final product met the international standards for biodiesel. The immobilized biocatalyst could be reused for at least five 12 h-batches maintaining 89.6% of the first-batch yield, showing the efficient catalyst recovery by applying an external magnetic field. ; This research was funded by the São Paulo Research Foundation (FAPESP, grant number 2016/10636-8), in part by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brasil (CAPES)–Finance Code 001, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, project numbers 405889/2016-0 and 308212/2017-7), and Ministerio de Ciencia e Innovación-Spanish Government (project number CTQ2017-86170-R). ; Peer reviewed

| openaire: EC/H2020/101006744/EU//EHLCATHOL Funding Information: This work is supported by the National Natural Science Foundation of China (21808163 and 21690083). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101006744. The content presented in this document represents the views of the authors, and the European Commission has no liability in respect of the content. Funding Information: This work is supported by the National Natural Science Foundation of China ( 21808163 and 21690083 ). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101006744 . The content presented in this document represents the views of the authors, and the European Commission has no liability in respect of the content. Publisher Copyright: © 2022 The Authors ; The depolymerization of enzymatic hydrolysis lignin (EHL) is examined over one-step hydrothermal-synthesized MoS2 in ethanol without hydrogen gas. Value-added aromatic molecules, mainly including alkyl-substituted phenols (A-Ps), are obtained without char or tar formation. The MoS2 samples prepared with different Mo and S precursors have been tested and the highest aromatic monomer yield of 226.4 mg/g EHL is achieved over the MoS2 prepared with thioacetamide and sodium molybdate as precursors (STA-MoS2) at 320 °C for 12 h. Proper ratios of Mo6+/Mo5+ (~0.46–0.65) and (Mo6++Mo5+)/Mo4+ (~0.47–0.62) on the surface of MoS2 catalysts are found to be significant for the achievement of high overall aromatic monomer yield. MoOxSy species with Mo5+ and S22- is proposed as the active site for the production of complex alkyl phenols via demethoxylation and alkylation. The carbon deposition and the exchanges of sulfur and oxygen atoms resulted from the oxidization are likely responsible for the deactivation of catalyst. ; Peer reviewed

Supercritical carbon dioxide (SC−CO2) has been used as solvent in the ethanolysis of fish oil rich with omega-3 polyunsaturated fatty acids (n-3 PUFAs) by Lipozyme 435. The effect of experimental conditions: initial ethanol-to-oil molar ratio (MR, 6:1-76:1), pressure (10–30 MPa), and temperature (323–343 K) on the reaction performance has been studied. Experimental results have been fitted to a kinetic model based on a Ping Pong Bi Bi mechanism. High accumulation of monoacylglycerides (MAGs) has been observed in short reaction times (90 min at MR = 76:1, 10 MPa, 323 K). Subsequent purification of reaction products by supercritical fluid extraction (SFE) in the experimental range 10–28 MPa and 298–333 K yielded an extract rich with fatty acid ethyl esters (FAEE) (up to 99.46%wt.), and a raffinate with up to 82.25%wt. MAG and 49.5%wt. n-3 PUFAs. ; Spanish Government through MINECO and the European Regional Development Fund (ERDF) for financial support [grant number CTQ2012-39131-C02-01] and RM's and AEI's contracts [BES-2013-063937, CTQ2015-64396-R]. To Junta de Castilla y León and ERDF for financial support [grant number BU055U16] and ÓBR's post-doctoral contract.