The Experts below are selected from a list of 2481 Experts worldwide ranked by ideXlab platform
Rafael Luque - One of the best experts on this subject based on the ideXlab platform.
-
tuneable Acidity in fluorinated al sba 15 materials for the esterification of Valeric Acid to alkyl valerates
2020Co-Authors: Miguel Blancosanchez, Alina M Balu, Rafael Luque, Evan Pfab, Noelia Lazaro, Antonio PinedaAbstract:The Acidity of Al-SBA-15 materials functionalized by ball milling with several niobium loadings (0. 25-1 wt.%) as well as with several fluorine loadings (by wet impregnation using NH4F as a precursor) was characterized and materials investigated in the esterification of Valeric Acid to alkyl valerates. The parent Al-SBA-15 support as well as the modified materials loaded with Nb and/or F have been catalysts synthesized characterized by X-ray diffraction (XRD), N2 physisorption measurements, and diffuse reflection infrared spectroscopy (DRIFT) among others. A special interest was paid on the Acidity of the materials that was investigated by temperature-programmed desorption of pyridine. Interestingly, the characterization results for the materials containing fluorine showed up an increase in the Acidity strength despite of a reduction in the number of Acid sites. The catalytic performance of the as-prepared catalysts was investigated in the microwave-assisted esterification reaction of Valeric Acid to valerate esters. Thus, while the materials modified with niobium exhibited a lower catalytic activity as compared with the catalytic support (Al-SBA-15), the materials loaded with fluorine either onto Al-SBA-15 or on Nb1%/Al-SBA-15 materials presented enhanced conversion values of Valeric Acid. Therefore, it can be said that the new Acid sites with enhanced strength formed by the incorporation of fluorine boost the esterification of Valeric Acid with alcohols to form the respective valerate ester.
-
sol gel immobilisation of lipases towards active and stable biocatalysts for the esterification of Valeric Acid
2018Co-Authors: Soledad Cebriangarcia, Alina M Balu, Rafael Luque, Araceli GarciaAbstract:Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of Valeric Acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80⁻85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of Valeric Acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.
-
nh4f modified al sba 15 materials for esterification of Valeric Acid to alkyl valerates
2018Co-Authors: Miguel Blancosanchez, Ana Franco, Antonio Pineda, Alina M Balu, Antonio A Romero, Rafael LuqueAbstract:Al-SBA-15 materials were functionalized by ball milling with several niobium loadings (0.25–1 wt.%) and/or with several F- loadings, using NH4F as a precursor. The catalysts synthesized in this study were characterised by X-ray diffraction (XRD), N2 porosimetry, and diffuse reflection infrared spectroscopy (DRIFT) among others. The prepared materials shown, form moderate to high catalytic activities in the microwave-assisted transformation of Valeric Acid to ethyl valerate via esterification. The incorporation of fluoride anions either into Al-SBA-15 or on Nb1%/Al-SBA-15 led to a linear increase in Valeric Acid conversion with the F− content. Thus, F− modified mesoporous aluminosilicates efficiently catalyze the transformation of Valeric Acid into alkyl valerate esters as renewable fuels.
-
ultrasound assisted esterification of Valeric Acid to alkyl valerates promoted by biosilicified lipases
2018Co-Authors: Soledad Cebriangarcia, Alina M Balu, Rafael LuqueAbstract:A novel, environmentally friendly and sustainable ultrasound-assisted methodology in the valorisation of Valeric Acid to alkyl valerate using a biosilicified Lipase from Candida Antarctica (LCA) is reported. This one-pot room temperature methodology of enzyme biosilicification leads to biosilicified lipases (Bio-LCA) with improved activity and reaction efficiency as compared to free enzymes. Yields in the ultrasound-promoted esterification of Valeric Acid was ca. 90% in two hours with 15% m/v of Bio-LCA (616 U/ mg biocatalyst enzymatic activity) and a molar ratio 1:2 (Valeric Acid: ethanol), slightly superior to that observed by the free enzyme (75% conversion, 583U/mg biocatalyst enzymatic activity). The reuse of enzymes in these conditions was tested and the results show a relatively good reusability of these biosilicified enzymes under the investigated conditions, particularly preserving fairly stable specific activities (616 vs 430 U/mg biocatalyst after four reuses).
Negar Ashariastani - One of the best experts on this subject based on the ideXlab platform.
-
ruddlesden popper phases of methylammonium based two dimensional perovskites with 5 ammonium Valeric Acid ava2man 1pbni3n 1 with n 1 2 and 3
2019Co-Authors: Negar Ashariastani, Farzaneh Jahanbakhshi, Marko Mladenovic, Anwar Q Alanazi, Iman Ahmadabadi, Mohammad Reza Ejtehadi, Ibrahim M Dar, Michael GratzelAbstract:5-Ammonium Valeric Acid (AVA) is a frequently used additive in the preparation of lead halide perovskites. However, its microscopic role as passivating, cross-linking, or templating agent is far fr...
-
ruddlesden popper phases of methylammonium based two dimensional perovskites with 5 ammonium Valeric Acid ava2man 1pbni3n 1 with n 1 2 and 3
2019Co-Authors: Negar Ashariastani, Farzaneh Jahanbakhshi, Marko Mladenovic, Anwar Q Alanazi, Iman Ahmadabadi, Mohammad Reza Ejtehadi, Michael Gratzel, Ursula RothlisbergerAbstract:5-Ammonium Valeric Acid (AVA) is a frequently used additive in the preparation of lead halide perovskites. However, its microscopic role as passivating, cross-linking, or templating agent is far from clear. In this work, we provide density functional theory-based structural models for the Ruddlesden–Popper (RP) phases of AVA2(CH3NH3)n−1PbnI3n+1 for n = 1, 2, and 3 and validate with experimental data on polycrystalline samples for n = 1. The structural and electronic properties of the AVA-based RP phases are compared to the ones of other linker families. In contrast to aromatic and aliphatic spacers without additional functional groups, the RP phases of AVA are characterized by the formation of a regular and stable H-bonding network between the carbonyl head groups of adjacent AVA molecules in opposite layers. Because of these additional interactions, the penetration depth of the organic layer into the perovskite sheet is reduced with direct consequences for its crystalline phase. The possibility of formin...
Keiichi Tomishige - One of the best experts on this subject based on the ideXlab platform.
-
structure and mechanism of titania supported platinum molybdenum catalyst for hydrodeoxygenation of 2 furancarboxylic Acid to Valeric Acid
2019Co-Authors: Takehiro Asano, Yoshinao Nakagawa, Masazumi Tamura, Keiichi TomishigeAbstract:Selective hydrodeoxygenation of 2-furancarboxylic Acid, which can be a relatively stable platform chemical from hemicellulose, to Valeric Acid was investigated in detail, and the reaction has been ...
-
Structure and Mechanism of Titania-Supported Platinum–Molybdenum Catalyst for Hydrodeoxygenation of 2‑Furancarboxylic Acid to Valeric Acid
2019Co-Authors: Takehiro Asano, Yoshinao Nakagawa, Masazumi Tamura, Keiichi TomishigeAbstract:Selective hydrodeoxygenation of 2-furancarboxylic Acid, which can be a relatively stable platform chemical from hemicellulose, to Valeric Acid was investigated in detail, and the reaction has been reported to be specifically promoted by supported Pt-MoOx catalysts. The dependence of catalytic performance of Pt-MoOx/TiO2 on loading amounts of Pt and Mo showed that the highest activity is obtained at around Mo ∼ 0.5 wt % when the Pt loading amount is fixed. With enough of the catalyst that can minimize the effect of deactivation, ∼60% yield of Valeric Acid was obtained over all Pt-MoOx/TiO2 catalysts with Pt ≥ 1 wt % and 0.5 wt % Mo loadings. Characterization results of Pt-MoOx/TiO2 catalysts with XRD and CO adsorption showed that the Pt particles (3–5 nm, depending on Pt loading amount) were not covered with MoOx species, suggesting that MoOx species were mainly located on the TiO2 support surface. Mo K-edge XAFS results suggest that the MoOx species in Pt-MoOx/TiO2 have a Mo(IV) valence state and some of the MoIVOx species have direct bonds with the Pt atom on Pt metal particles. The number of the direct Pt–Mo bonds became smaller after catalytic use, which can be related to the deactivation. Therefore, the Pt–Mo bimetallic site can be the catalytically active site. Based on the solvent effect, reactivity trends of related substrates, and reaction orders in kinetics, a reaction mechanism is proposed where the ring is opened after addition of one hydrogen atom to the 2-position of the furan ring
-
selective hydrodeoxygenation of 2 furancarboxylic Acid to Valeric Acid over molybdenum oxide modified platinum catalyst
2016Co-Authors: Takehiro Asano, Yoshinao Nakagawa, Masazumi Tamura, Keiichi TomishigeAbstract:2-Furancarboxylic Acid (FCA), produced by oxidation of furfural, is rarely used as a platform molecule. Metal-oxide-supported Pt-MoOx catalysts were effective for hydrodeoxygenation of FCA to Valeric Acid (VA) in water solvent. The highest VA yield is 51% over Pt-MoOx/TiO2 catalyst under 1.5 MPa H2 at 413 K. Other metal combinations (M-MoOx, M = Rh, Pd, Ru, Ir, Au, none; Pt-M′Ox, M′= V, W, Re, none) showed very low VA yield. This catalyst system was applicable to the hydrodeoxygenation of 2,5-furandicarboxylic Acid (FDCA), and adipic Acid (AA) was obtained with 21% yield at 473 K.
Marko Mladenovic - One of the best experts on this subject based on the ideXlab platform.
-
ruddlesden popper phases of methylammonium based two dimensional perovskites with 5 ammonium Valeric Acid ava2man 1pbni3n 1 with n 1 2 and 3
2019Co-Authors: Negar Ashariastani, Farzaneh Jahanbakhshi, Marko Mladenovic, Anwar Q Alanazi, Iman Ahmadabadi, Mohammad Reza Ejtehadi, Ibrahim M Dar, Michael GratzelAbstract:5-Ammonium Valeric Acid (AVA) is a frequently used additive in the preparation of lead halide perovskites. However, its microscopic role as passivating, cross-linking, or templating agent is far fr...
-
ruddlesden popper phases of methylammonium based two dimensional perovskites with 5 ammonium Valeric Acid ava2man 1pbni3n 1 with n 1 2 and 3
2019Co-Authors: Negar Ashariastani, Farzaneh Jahanbakhshi, Marko Mladenovic, Anwar Q Alanazi, Iman Ahmadabadi, Mohammad Reza Ejtehadi, Michael Gratzel, Ursula RothlisbergerAbstract:5-Ammonium Valeric Acid (AVA) is a frequently used additive in the preparation of lead halide perovskites. However, its microscopic role as passivating, cross-linking, or templating agent is far from clear. In this work, we provide density functional theory-based structural models for the Ruddlesden–Popper (RP) phases of AVA2(CH3NH3)n−1PbnI3n+1 for n = 1, 2, and 3 and validate with experimental data on polycrystalline samples for n = 1. The structural and electronic properties of the AVA-based RP phases are compared to the ones of other linker families. In contrast to aromatic and aliphatic spacers without additional functional groups, the RP phases of AVA are characterized by the formation of a regular and stable H-bonding network between the carbonyl head groups of adjacent AVA molecules in opposite layers. Because of these additional interactions, the penetration depth of the organic layer into the perovskite sheet is reduced with direct consequences for its crystalline phase. The possibility of formin...
Marcos L Corazza - One of the best experts on this subject based on the ideXlab platform.
-
vapor liquid and liquid liquid equilibrium modeling of systems involving ethanol water and ethyl valerate Valeric Acid using the pc saft equation of state
2018Co-Authors: Luis R S Kanda, Julia Trancoso Fernandes Dos Santos, Francisco Carlos Paes, Fernando Augusto Pedersen Voll, Kallynca Carvalho Dos Santos, Marcos L CorazzaAbstract:Abstract Valeric biofuels are renewable and environmental friendly fuels whose production avoids the competition with the food industry for edible oils since its route of production uses lignocellulose of residue from crops as raw material. After the reaction steps several purification operations are necessary for the Valeric biofuels to meet purity standards. Therefore, it is of utter importance the knowledge of both liquid-liquid (LLE) and vapor-liquid (VLE) equilibrium behavior of species present in the process, such as ethyl valerate, Valeric Acid, ethanol and water. In this sense, the objective of this work is to provide a general overview for the phase equilibria of the system aforementioned using experimental data collected as background for the thermodynamic modeling. Experimental data concerning to LLE were evaluated at local atmospheric pressure (around 90.9 kPa) and 293.15 K and 318.15 K, while VLE data were collected at several different controlled pressures, ranging from approximately 7 kPa to local atmospheric pressure (around 91 kPa). UNIFAC and PC-SAFT (Perturbed Chain form of the Statistical Associating Fluid Theory) were used to perform the thermodynamic modeling. The results obtained in this work are helpful to prove the importance of carefully evaluate the interactions between the molecules present in the system. Otherwise, the design of unit operations could underestimate the number of stages required for the purification, causing the products to not reach purity specifications.
-
phase equilibrium measurements and thermodynamic modelling for the systems involving Valeric Acid ethanol ethyl valerate and water plus co2
2017Co-Authors: Bruno Aguilar Veiga, Julia Trancoso Fernandes Dos Santos, Luiz Fernando De Lima Luz, Marcos L CorazzaAbstract:Abstract This work reports phase equilibrium measurements for binary, ternary, quaternary and five components mixtures of CO2, ethanol, Valeric Acid, water and ethyl valerate at high pressures. Experiments were carried out using a high-pressure variable-volume view cell with operating temperatures ranging from 303.15 K to 353.15 K and pressures up to 15 MPa. The CO2 mole fraction ranged from 0.4780 to 0.9412 for the binary system {CO2(1) + Valeric Acid(2)}, from 0.3801 to 0.9811 for {CO2(1) + ethyl valerate(2)}, from 0.5649 to 0.9193 for the ternary system {CO2(1) + ethanol(2) + Valeric Acid(3)} at an ethanol to Valeric Acid mole ratio of (3:1) and from 0.5907 to 0.9373 for {CO2(1) + ethanol(2) + ethyl valerate(3)} at an ethanol to ethyl valerate mole ratio of (1:1). For the quaternary {CO2(1) + ethanol(2) + water(3) + ethyl valerate(4)} and the five components system {CO2(1) + ethanol(2) + Valeric Acid(3) + water(4) + ethyl valerate(5)} fixed compositions were investigated at CO2 mole fraction of 0.7336 and 0.7211, respectively, while the mole ratio of other compounds were fixed at typical esterification conditions. For the systems investigated, vapour-liquid (VL), liquid-liquid (LL) and vapour-liquid-liquid (VLL) phase transitions were observed. The experimental data sets were successfully modeled using the Peng-Robinson cubic equation of state with the Boston-Mathias alpha function and using the van der Walls quadratic mixing rule. The PR-BM showed good performance in the prediction of the phase transitions for the ternary, quaternary and five components systems based on the binary interaction parameters obtained from the binary CO2 + Valeric Acid, CO2 + ethyl valerate and CO2 + ethanol experimental data.
-
liquid liquid equilibrium of ternary systems comprising ethyl valerate 1 water 2 ethanol 3 and Valeric Acid 4
2017Co-Authors: Francisco Carlos Paes, Luis R S Kanda, Fernando Augusto Pedersen Voll, Marcos L CorazzaAbstract:Abstract Valeric biofuels stand for a promising energy source, since they are generated from the refining process of crop residues, which converts lignocellulose into the Valeric biofuel (or Valeric ester). In order to achieve a high grade Valeric ester, several washing steps are required and eventually results in the formation of two liquid phases (water-rich and ester-rich phases). In this context, the objective of this study is the experimental determination of liquid-liquid equilibrium (LLE) concerning chemical species present during the ethyl esterification of Valeric Acid (Valeric Acid, ethanol, ethyl valerate and water). Results were obtained for the LLE of ternary systems comprised of binodal curves and tie-lines at atmospheric pressure (91.1 kPa) and 293.15 K and 318.15 K. The experimental values obtained were modelled using NRTL, UNIQUAC and UNIFAC-LL Gibbs energy models. Both NRTL and UNIQUAC models were able to correlate satisfactorily the experimental results, while UNIFAC-LL predictions provided greater deviations.
