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171.
Selective hydrogenation of cinnamaldehyde using Pd catalysts supported on Mg/Al mixed oxides: Influence of the Pd incorporation method 下载免费PDF全文
María J. Martínez‐Ortiz Miguel A. de la Rosa‐Guzmán Jorge R. Vargas‐García Jorge L. Flores‐Moreno Nancy Castillo Ariel Guzmán‐Vargas Sara Morandi Rosa M. Pérez‐Gutiérrez 《加拿大化工杂志》2018,96(1):297-306
A series of hydrotalcite‐like compounds was synthesized by varying Mg/Al molar ratio with values of 2, 3, and 4. After thermal treatment at 823 K, the corresponding mixed oxides were obtained and used as catalytic supports. The incorporation of a Pd metallic phase (0.5 g/g loading), was carried out by two methods: 1) in situ vapour phase thermal decomposition, and 2) impregnation by organic method. Fresh and calcined samples were characterized by XRD and N2 sorption experiments. The basic and metal functions were analyzed by CO2‐TPD and H2‐TPR. The Pd‐support interaction was studied by FTIR spectroscopy using CO as a probe molecule while the morphology of Pd nanoparticles on the catalysts was studied by SEM, HRTEM, and theoretical simulation using the Fast Fourier Transform (FFT) method. Finally, the catalytic activity results showed a higher conversion towards hydrocinnamaldehyde in the cinnamaldehyde hydrogenation reaction for the catalysts prepared by vapour phase thermal decomposition, compared with those prepared by organic method, showing the significant dependence on the catalytic activity and the Pd incorporation method. 相似文献
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J. Paulo García‐Sandoval A. Martín del Campo F. Bautista O. Manero Jorge E. Puig 《American Institute of Chemical Engineers》2018,64(6):2277-2292
The rheological behavior of micellar solutions is analyzed under nonhomogeneous velocity and stress flow conditions. The framework is based on the extended irreversible thermodynamics and the transient network formulation coupled to the underlying kinetics embodying two relevant processes: formation of wormlike chains from a free micellar solution through a thermally activated process and their flow induced degradation. The second kinetic process consists in the formation of entanglements from the free wormlike chains and their flow‐induced breakage. These processes are modeled in a coupled kinetic scheme constituted by a set of reversible kinetic equations describing the evolution in average of the three microstates (free short rod‐like micelles, free wormlike chains, and entangled wormlike chains) that reflect the complexity of macromolecular interactions. The predictions of the shear stress and first normal stress difference as a function of shear‐rate under banded flow are in good agreement with experimental data. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2277–2292, 2018 相似文献
175.
Ajna Tóth Kateryna V. Voitko Olga Bakalinska Gennadiy P. Prykhod’ko Imre Bertóti Amelia Martínez-Alonso Juan M.D. Tascón Vladimir M. Gun’ko Krisztina László 《Carbon》2012,50(2):577-585
The poor compatibility of carbon materials with different dispersion media can be overcome by surface functionalization. In this work, multiwall carbon nanotubes (MWCNTs) were doped by oxygen and nitrogen at low concentrations. Morphological and structural changes caused by chemical treatment were monitored using nitrogen, propane and water vapor adsorption measurements. Pore size distribution (PSD) functions derived from various models are compared. The contribution of slit-shaped pores to the total surface area available for adsorbed molecules is smaller than that of cylindrical pores. Functionalities with heteroatoms (both O and N) enhance water adsorption onto MWCNTs. However, no statistical difference is observed between the water adsorption properties of O- or N-containing MWCNTs. 相似文献
176.
Marina Enterría Fabián Suárez-García Amelia Martínez-Alonso Juan M.D. Tascón 《Carbon》2012,50(10):3826-3835
Hierarchical micro–mesoporous carbons with high porosity development and ordered structure were prepared. The innovative proposal consists in developing microporosity in ordered mesoporous carbon by chemical activation in template presence in order to minimize the structural damage. Thus, we have directly carried out the chemical activation of a mesoporous carbon/silica composite with KOH. The effect on mesoporous ordered structure of both KOH/carbon ratio and activation temperature has been studied. Following chemical activation the specific surface area is increased from 341 to 1757 m2/g and the micropore volume becomes almost six times larger than initial value. Although a slight widening of the mesopore distribution and an increase in the mesopore volume has been observed during activation, TEM and XRD results reveal an excellent conservation of the ordered mesoporous structure during activation even at conditions well above the limits that a CMK-3 type carbon can resist. 相似文献
177.
Jordi Palau Josep M. Penya‐Roja Carmen Gabaldón Francisco Javier Álvarez‐Hornos Vicente Martínez‐Soria 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(1):65-72
BACKGROUND: The integration of UV photocatalysis and biofiltration seems to be a promising combination of technologies for the removal of hydrophobic and poorly biodegradable air pollutants. The influence of pre‐treatments based on UV254 nm photocatalysis and photo‐oxidation on the biofiltration of toluene as a target compound was evaluated in a controlled long‐term experimental study using different system configurations: a standalone biofilter, a combined UV photocatalytic reactor‐biofilter, and a combined UV photo‐oxidation reactor (without catalyst)‐biofilter. RESULTS: Under the operational conditions used (residence time of 2.7 s and toluene concentrations 600–1200 mg C m?3), relatively low removal efficiencies (6–3%) were reached in the photocatalytic reactor and no degradation of toluene was found when the photo‐oxidation reactor was operated without catalyst. A noticeable improvement in the performance of the biofilter combined with a photocatalytic reactor was observed, and the elimination capacity of the biological process increased by more than 12 g C h?1 m?3 at the inlet loads studied of 50–100 g C h?1 m?3. No positive effect on toluene removal was observed for the combination of UV photoreactor and biofilter. CONCLUSIONS: Biofilter pre‐treatment based on UV254 nm photocatalysis showed promising results for the removal of hydrophobic and recalcitrant air pollutants, providing synergistic improvement in the removal of toluene. Copyright © 2011 Society of Chemical Industry 相似文献
178.
María J. Martín de Vidales José Robles‐Molina Juan C. Domínguez‐Romero Pablo Cañizares Cristina Sáez Antonio Molina‐Díaz Manuel A. Rodrigo 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(10):1441-1449
BACKGROUND: Sulfamethoxazole (SMX, used as a model bacteriostatic antibiotic) is persistent to conventional biological treatments of wastewaters. In this work, conductive‐diamond electrochemical oxidation (CDEO) was found to be an effective technology for its removal from the effluents of conventional wastewater treatment plants. RESULTS: The use of CDEO has been evaluated for the removal of the antibiotic SMX from water and wastewaters. The results show that CDEO can reduce the concentration of this organic pollutant to values below 0.1 µg dm?3. The variation of the SMX concentration during electrolysis shows a complex shape with a plateau zone that increases in size with the initial concentration of SMX. This complex trend is not observed in the changes of TOC, which seems to indicate that the CDEO of SMX solutions does not lead directly to the generation of carbon dioxide as a final product. A tentative reaction pathway has been proposed based on a thorough analysis of the reaction mixture, in which the main intermediate products were identified. The use of liquid chromatography time‐of‐flight mass spectrometry (LC‐TOFMS) allowed the identification of nine organic intermediates (with Mw 98, 108, 172, 173, 197, 203, 227, 269 and 287) during the electrolysis and the concentration of these compounds depends on the initial SMX concentration and on the current density applied. CONCLUSIONS: CDEO is able to reduce the concentration of the organic pollutant below 0.1 mg dm?3. SMX removal is faster than that of TOC. This fact indicates the formation of reaction intermediates. Analytical techniques show that nine reaction intermediates are generated in the system, and that their concentration depends on the initial SMX concentration and on the current density used. Copyright © 2012 Society of Chemical Industry 相似文献
179.
The methanolic extract of the marine sponge Ircinia felix has yielded nine novel fatty acid esters, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-22-methyltricosadienoate, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-tetracosadienoate, (7E, 12E, 18R, 20Z)-variabilin hexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 10-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 15-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 14-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 9-octadecenoate, (7E, 12E, 18R, 20Z)-variabilin octadecanoate, and (7E, 12E, 18R, 20Z)-variabilin 2,11-dimethyloctadecanoate, along with the recently described (7E, 12E, 18R, 20Z)-variabilin 11-methyloctadecanoate. The characterization of the new fatty acids (5Z, 9Z)-22-methyltricosadienoic and 2,11-dimethyloctadecanoic acids is also described. The chemical structures were determined by
extensive spectroscopic, chromatographic, and chemical analyses. 相似文献
180.