Search results for "Catalytic"
showing 10 items of 394 documents
Distant Homology Modeling of LCAT and Its Validation through In Silico Targeting and In Vitro and In Vivo Assays
2013
LCAT (lecithin:cholesterol acyltransferase) catalyzes the transacylation of a fatty acid of lecithin to cholesterol, generating a cholesteryl ester and lysolecithin. The knowledge of LCAT atomic structure and the identification of the amino acids relevant in controlling its structure and function are expected to be very helpful to understand the enzyme catalytic mechanism, as involved in HDL cholesterol metabolism. However - after an early report in the late '90 s - no recent advance has been made about LCAT three-dimensional structure. In this paper, we propose an LCAT atomistic model, built following the most up-to-date molecular modeling approaches, and exploiting newly solved crystallog…
Heterogeneous photocatalytic aqueous succinic acid formation from maleic acid reduction
2022
This study reports the anaerobic reduction of maleic acid to succinic acid in aqueous dispersion of different TiO2 based photocatalysts. Some home prepared and commercial solids containing different polymorphic phases of TiO2 and loaded with Pt and Ru were compared at different acidic pHs. The aim of the work was to verify the feasibility of the process and to determine the best samples and the optimal experimental conditions of the reaction. The best selectivity towards succinic acid was 23.2 % at 70 % of maleic acid conversion. Fumaric acid was also formed as another high added value compound, and its quantity was related to the experimental conditions and the photocatalyst used.
High Turnover Catalase Activity of a Mixed‐Valence Mn II Mn III Complex with Terminal Carboxylate Donors
2015
The neutral dimanganese(II,III) complex [Mn-2(BCPMP)-(OAc)(2)] [1; BCPMP3- = 2,6-bis({(carboxymethyl)[(1-pyridyl)-methyl] amino} methyl)-4-methylphenolato] has been synthesized and characterized. The complex contains two terminal carboxylate donors. Complex 1 was found to be an effective catalyst for the disproportionation of H2O2 with high catalytic rate and a turnover number of 7500, the highest turnover reported to date for a catalase mimic. The rates and TON were significantly higher than recorded for a dicationic dimanganese( II,III) counterpart ([Mn-2(BPBP)(OAc)(2)]center dot(ClO4)(2), 2; BPBP- = 2,6-bis{[bis(2-pyridylmethyl)amino]methyl}-4-butylphen-olato), which lacks the terminal c…
Electronic and optical properties of pristine, N- and S-doped water-covered TiO2 nanotube surfaces
2019
For rational design and improvement of electronic and optical properties of water-splitting photocatalysts, the ability to control the band edge positions relative to the water redox potentials and the photoresponse as a function of environmental conditions is essential. We combine ab initio molecular dynamics simulations with ab initio many-body theoretical calculations to predict the bandgap and band edge energies, as well as the absorption spectrum of pristine and N- and S-doped TiO2 nanotubes using the DFT+U and G0W0 approaches. Both levels of theory show similar trends, and N+S-codoping appears to be the optimal system for photocatalytic water splitting both in dry and humid conditions…
Rare-earth ion exchanged Cu-SSZ-13 zeolite from organotemplate-free synthesis with enhanced hydrothermal stability in NH3-SCR of NOx
2019
The relatively low hydrothermal stability of Al-rich Cu-SSZ-13 catalysts hinders their practical application in ammonia selective catalytic reduction (NH3-SCR) reaction. Rare-earth ions were introduced into the Al-rich SSZ-13 zeolite using an organotemplate-free synthesis prior to the exchange of Cu2+ ions. Among the rare-earth ions tested (Ce, La, Sm, Y, Yb), Y shows significant enhancement of the hydrothermal stability and NH3-SCR activities after severe hydrothermal aging at 800 °C for 16 h when compared with Cu-SSZ-13 without Y. Cu–Y-SSZ-13 catalysts with various amounts of Y were prepared, and it is found that with increasing Y content, the low temperature NO conversions can be improve…
Structural and electrical properties of cerium tungstate: Application to methane conversion
2020
International audience; The catalytic efficiency as well as the electrical conduction mechanism of Ce2(WO4)3 powders synthetized for the oxidation of methane were investigated. Total and partial oxidation reactions were observed in the temperature range between 600 and 750 °C under CH4/dry air flux, for low CH4 concentrations. The electrical conduction mechanism is based on electron tunneling at low temperature (< 650 °C) and hopping over an ion barrier at high temperature, which favors the catalytic oxidation of CH4 in air; these mechanisms occur during the partial and total oxidation under weak gas flow. The occurrence of these types of conduction mechanism was related both to the distort…
Highly Active Hydrogenation Catalysts Based on Pd Nanoparticles Dispersed along Hierarchical Porous Silica Covered with Polydopamine as Interfacial G…
2020
New catalysts based on Pd(0) nanoparticles (Pd NPs) on a bimodal porous silica of the UVM-7/polydopamine (PDA) support have been synthesized following two preparative strategies based on the sequential or joint incorporation of two components of the composite (Pd and PDA). We analyzed the role played by the PDA as &lsquo
Coupling of membrane and photocatalytic technologies for selective formation of high added value chemicals
2020
Abstract This review presents a survey of some heterogeneous photocatalytic processes for the synthesis of high-value added compounds carried out in photocatalytic membrane reactors (PMRs). The two technologies can be easily integrated due to the similar conditions at which they usually operate. Furthermore, significant advantages derive from the coupling and in some cases also synergistic effects can be observed. These features have been highlighted for the photocatalytic syntheses reviewed along with engineering and design aspects investigated for some industrially relevant high-value added compounds. Notably, photocatalytic syntheses carried out in PMRs are still rare mainly because inte…
CO2 to Liquid Fuels: Photocatalytic Conversion in a Continuous Membrane Reactor
2018
The photocatalytic reduction of CO, into value-added chemicals using sunlight is a promising approach to promote energy-bearing products, mitigating the adverse effects of anthropogenic CO2 emissions. In this work, exfoliated C3N4 was incorporated into Nafion matrix and used in a continuous photocatalytic reactor for converting CO2 into liquid fuels. Comprehensive structural and morphological diffuse reflectance spectroscopy (DRS), FT-IR, ATR-IR, and SEM measurements were performed for C3N4-loaded Nafion membrane and then compared with those of a Nafion membrane without any catalyst. The synergic effect of C3N4 organic catalyst embedded in a Nafion dense matrix and a continuous operating mo…
C-, N-, S-, and Fe-Doped TiO2 and SrTiO3 Nanotubes for Visible-Light-Driven Photocatalytic Water Splitting: Prediction from First Principles
2015
The ground state electronic structure and the formation energies of both TiO2 and SrTiO3 nanotubes (NTs) containing CO, NO, SO, and FeTi substitutional impurities are studied using first-principles calculations. We observe that N and S dopants in TiO2 NTs lead to an enhancement of their visible-light-driven photocatalytic response, thereby increasing their ability to split H2O molecules. The differences between the highest occupied and lowest unoccupied impurity levels inside the band gap (HOIL and LUIL, respectively) are reduced in these defective nanotubes down to 2.4 and 2.5 eV for N and S doping, respectively. The band gap of an NO+SO codoped titania nanotube is narrowed down to 2.2 eV …