539-82-2Relevant articles and documents
Carlson,Helquist
, p. 173 (1969)
Thermoalkalophilic lipase from an extremely halophilic bacterial strain Bacillus atrophaeus FSHM2: Purification, biochemical characterization and application
Ameri, Atefeh,Shakibaie, Mojtaba,Faramarzi, Mohammad Ali,Ameri, Alieh,Amirpour-Rostami, Sahar,Rahimi, Hamid Reza,Forootanfar, Hamid
, p. 151 - 160 (2017)
The present study was designed to isolate and identify an extremely halophilic lipase-producing bacterial strain, purify and characterize the related enzyme and evaluate its application for ethyl and methyl valerate synthesis. Among four halophilic isolates, the lipolytic ability of one isolate (identified as Bacillus atrophaeus FSHM2) was confirmed. The enzyme (designated as BaL) was purified using three sequential steps of ethanol precipitation and dialysis, Q-Sepharose XL anion-exchange chromatography and SP Sepharose cation-exchange chromatography with a final yield of 9.9% and a purification factor of 31.8. The purified BaL (Mw~85 kDa) was most active at 70 °C and pH 9 in the presence of 4?M NaCl and retained 58.7% of its initial activity after 150 min of incubation at 80 °C. The enzyme was inhibited by Cd2+ (35.6 ± 1.7%) but activated by Ca2+ (132.4 ± 2.2%). Evaluation of BaL's stability in the presence of organic solvents showed that xylene (25%) enhanced the relative activity of the enzyme to 334.2 ± 0.6% after 1 h of incubation. The results of esterification studies using the purified BaL revealed that maximum ethyl valerate (88.5%) and methyl valerate (67.5%) synthesis occurred in the organic solvent medium (xylene) after 48 h of incubation at 50 °C.
The relevance of Lewis acid sites on the gas phase reaction of levulinic acid into ethyl valerate using CoSBA-xAl bifunctional catalysts
Cecilia, J. A.,Dumesic, J. A.,Jiménez-Gómez, C. P.,López Granados, M.,Maireles-Torres, P.,Mariscal, R.,Mu?oz-Olasagasti, M.
, p. 4280 - 4293 (2021/06/30)
A series of Co supported on Al-modified SBA-15 catalysts has been studied in the gas phase direct transformation of levulinic acid (LA) into ethyl valerate (EV) using a continuous fixed-bed reactor and ethanol as solvent. It was observed that once the intermediate product gamma-valerolactone (GVL) has been formed, the presence of aluminum is required for the selective transformation to EV. Three Lewis acid sites (LAS) are identified (from highest to lowest acid strength): aluminum ions in tetrahedral and octahedral coordination and Co2+sites. The intrinsic activity of these LAS for the key reaction, the GVL ring opening, decreases with the strength of these acid sites, but so does the undesirable formation of coke, also catalyzed by these centers. The best catalyst was that with the highest Al content, CoSBA-2.5Al, that reached an EV yield of up to 70%. This result is associated with the presence of LAS attributed to the presence of Co2+surface species that, although having low intrinsic activity in the selective GVL ring-opening reaction, are highly concentrated in this sample and also possess less activity in the undesirable and deactivating formation of coke. These Co2+LAS have been stabilized by incorporation of aluminum into the support, modifying the reducibility and dispersion of cobalt species. Additionally, the lower proportion of metallic Co species decreases the hydrogenating capacity of this catalyst. This decrease is a positive result because it prevents GVL hydrogenation to undesired products. This catalyst also showed promising stability in a 140 h on-stream run.
Catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone over supported MoS2catalysts
Diao, Xinyong,Ji, Na,Jiang, Sinan,Liu, Caixia,Liu, Qingling,Liu, Zhenyu,Lu, Xuebin,Ma, Degang,Song, Chunfeng,Yu, Zhihao
, p. 5062 - 5076 (2021/08/16)
The hydrogenation of levulinate esters to γ-valerolactone (GVL) is an important step in the transformation of biomass into biofuels. It is attractive to develop new efficient systems for the catalytic transfer hydrogenation (CTH) of levulinate esters to value-added GVL. In this work, a series of MoS2-based supported catalysts were prepared via an impregnation method for the CTH of biomass-derived ethyl levulinate (EL) to GVL. By comprehensive characterization and catalytic measurements, we found that the CTH activity of EL to GVL is closely related to the MoS2 morphology and acid distribution on the support. Among the catalysts with different supports, the AC support with abundant Lewis acid sites and large surface area facilitated the high dispersion of low stacked MoS2 slabs, and the MoS2-acid synergistic catalysis contributed to the superior activity and selectivity. The conversion of EL and the selectivity of GVL reached 97.2% and 91.2% under optimized conditions over the MoS2/AC catalyst (230 °C, 1 MPa H2, 1.5 h), respectively. We also conducted reaction kinetic experiments to reveal the relationship between the active site of the MoS2/AC catalyst and its catalytic performance, and the plausible reaction pathway and mechanism over MoS2/AC was proposed. The catalytic performance gradually declined during recycling tests due to the oxidation of MoS2 and can be easily recovered by resulfuration.
Eco-Friendly Natural Clay: Montmorillonite Modified with Nickel or Ruthenium as an Effective Catalyst in Gamma-Valerolactone Synthesis
?erveny, Libor,Trejbal, Ji?í,Vaňková, Michaela,Vrbková, Eva,Vysko?ilová, Eli?ka
, (2021/07/25)
Ni/Ru metals supported on cheap and available support montmorillonite K10 were used for the selective hydrogenation of levulinic acid to γ-valerolactone. Different loadings of the metals were applied by the impregnation method, and detailed characterization was performed (UV–VIS, XRD, TPR, TPD, particle size distribution, SEM, XRF). Metals’ homogeneous distribution on the surface was confirmed. The selectivity to the desired product was almost independent on the used material. A detailed study of the influence of solvents on the studied reaction was also performed—protic alcohol-based solvents caused the formation of levulinic and valeric acid esters in the reaction mixture. The selectivity was influenced mainly by the alcohol structure (the highest selectivity obtained using isopropyl alcohol and sec-butanol). Mainly the solvent’s donor number (except ethanol) influenced the reaction rate. The prepared catalysts are promising, available, and cheap materials for the studied reaction. Solvent may significantly influence the yield of γ-valerolactone. Graphic Abstract: [Figure not available: see fulltext.].