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30 results on '"Aguirre, Alejo"'

17. Rational Design of Bioinspired Nanocomposites with Tunable Catalytic Activity

Author

Hendrikse, Hans, Aguirre, Alejo, van der Weijden, Arno, Meeussen, Anne S., Neira d'Angelo, M.F. (Fernanda), Noorduin, Willem L., Hendrikse, Hans, Aguirre, Alejo, van der Weijden, Arno, Meeussen, Anne S., Neira d'Angelo, M.F. (Fernanda), and Noorduin, Willem L.

Abstract

Biological assembly processes offer inspiration for ordering building blocks across multiple length scales into advanced functional materials. Such bioinspired strategies are attractive for assembling supported catalysts, where shaping and structuring across length scales are essential for their performance but still remain tremendously difficult to achieve. Here, we present a simple bioinspired route toward supported catalysts with tunable activity and selectivity. We coprecipitate shape-controlled nanocomposites with large specific surface areas of barium carbonate nanocrystals that are uniformly embedded in a silica support. Subsequently, we exchange the barium carbonate to cobalt while preserving the nanoscopic layout and microscopic shape, and demonstrate their catalytic performances in the Fischer–Tropsch synthesis as a case study. Control over the crystal size between 10 and 17 nm offers tunable activity and selectivity for shorter (C5–C11) and longer (C20+) hydrocarbons, respectively. Hence, these results open simple, versatile, and scalable routes to tunable and highly reactive bioinspired catalysts.

Published
2021

20. Propoxylation of fatty amines: Switching from batch to flow

Author

Müller, Pia, Aguirre, Alejo, Ljungdahl, Thomas, van der Schaaf, John, Müller, Pia, Aguirre, Alejo, Ljungdahl, Thomas, and van der Schaaf, John

Abstract

The ethoxylation and propoxylation of fatty amines are important industrial reactions commonly performed in de-intensified semi-batch reactors. The present study aims to intensify these reactions by transferring the process to continuous processing. Therefore, the propoxylation of octylamine, as model system, was performed in a batch reactor and in a micro tubular reactor. The micro tubular reactor operated with a single liquid phase at 15 bar pressure. The batch study found valuable kinetic and solubility information in the temperature range of 120°C-160°C. Moreover, a switch-flow method in the micro tubular reactor combined with inline FTIR gave a more detailed understanding of the reaction kinetics. In the micro tubular reactor, all PO was added in the feed according to stoichiometry, which led to a process intensification factor of 3.7 compared to fed-batch gas phase addition at maximum 2 bar.

Published
2020

24. Monitoring Reaction Intermediates in Plasma-Driven SO2, NO, and NO2Remediation Chemistry Using In Situ SERS Spectroscopy

Author

Li, Shujin, Zhao, Bofan, Aguirre, Alejo, Wang, Yu, Li, Ruoxi, Yang, Sisi, Aravind, Indu, Cai, Zhi, Chen, Ran, Jensen, Lasse, and Cronin, Stephen B.

Abstract

In situ surface-enhanced Raman scattering (SERS) spectroscopy is used to identify the key reaction intermediates during the plasma-based removal of NO and SO2under dry and wet conditions on Ag nanoparticles. Density functional theory (DFT) calculations are used to confirm the experimental observations by calculating the vibrational modes of the surface-bound intermediate species. Here, we provide spectroscopic evidence that the wet plasma increases the SO2and the NOxremoval through the formation of highly reactive OH radicals, driving the reactions to H2SO4and HNO3, respectively. We observed the formation of SO3and SO4species in the SO2wet-plasma-driven remediation, while in the dry plasma, we only identified SO3adsorbed on the Ag surface. During the removal of NO in the dry and wet plasma, both NO2and NO3species were observed on the Ag surface; however, the concentration of NO3species was enhanced under wet-plasma conditions. By closing the loop between the experimental and DFT-calculated spectra, we identified not only the adsorbed species associated with each peak in the SERS spectra but also their orientation and adsorption site, providing a detailed atomistic picture of the chemical reaction pathway and surface interaction chemistry.

Published
2021
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25. Mechanistics and kinetics studies using spectroscopic micro-reactors

Author

Aguirre, Alejo, Collins, Sebastián Enrique, Bañares, Miguel Ángel, Blesa, Miguel Ángel, Miró, Eduardo Ernesto, and Berli, Claudio Luis Alberto

Subjects
DRIFT, In-situ, Micro-reactors, Operando, Catálisis, Micro-reactores, Catalysis, ATR-FTIR
Abstract

Fil: Aguirre, Alejo. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina. Interpretar adecuadamente las interacciones moleculares, los mecanismos de reacción y la cinética intrínseca es de fundamental importancia para realizar un diseño racional de nuevos catalizadores. En esta tesis doctoral se presenta la implementación de metodologías novedosas de análisis cinético por medio de técnicas de espectroscopia molecular in-situ y operando para el estudio de reacciones catalíticas heterogéneas. En particular, se utilizó la espectroscopia infrarroja por transformada de Fourier (FTIR) en modo de reflexión total atenuada (ATR) para estudiar la interacción líquido(reactivo)/sólido(catalizador) y en modo de reflectancia difusa (DRIFT) para el estudio de reacciones que ocurren en la interfase gas(reactivo)/sólido(catalizador). Uno de los mayores desafíos de las espectroscopias in-situ es la identificación de las especies activas de la reacción, es decir, los intermediarios. Para tal fin se presenta en esta Tesis la implementación y desarrollo de la técnica de espectroscopia de excitación modulada (MES) en conjunto con el algoritmo de detección sensible de fase (PSD) para la detección sensible y selectiva de intermediarios de reacción. Más aún para obtener información cinética cuantitativa de las especies activas, es necesario el desarrollo de celdas espectroscópicas que se comporten como microreactores ideales. Por lo tanto, un aspecto primordial de esta tesis es el diseño y fabricación de estos dispositivos. Se espera que los resultados presentados en esta tesis doctoral permitan sentar las bases para el desarrollo de metodologías cuantitativas para la determinación de velocidades de reacción verdaderas de procesos superficiales, tanto en fase líquida como gas, empleando técnicas de espectroscopia molecular en estudios operando. Appropriate interpretation of molecular interactions, reaction mechanisms and intrinsic kinetic is of fundamental importance for a rational design of new catalysts. In this doctoral thesis is presented the implementation of novel kinetic analysis methodologies by in-situ and operando techniques for study heterogeneous catalytic reactions. In particular, Fourier transform infrared spectroscopy (FTIR) in attenuated total reflection (ATR) mode and diffuse reflectance infrared Fourier transform (DRIFT) were used to study interactions in liquid(reactive)/solid(catalyst) and gas(reactive)/solid(catalyst) systems, respectively. One of the main challenges for in-situ spectroscopy is the identification of the active species of the reaction, ie intermediaries. For this purpose, in this thesis is presented the implementation and development of the modulated excitation spectroscopy (MES) technique in combination with the phase sensitive detection (PSD) algorithm for sensitive and selective detection of reaction intermediates. Moreover, to obtain quantitative kinetic information of the active species, the spectroscopic cell must perform as an actual catalytic reactor. Therefore, a key aspect of this thesis is the design and construction of these devices. It is expected that the results presented in this thesis lay the groundwork for the development of quantitative methodologies for determining surface reaction rates in surface processes, in both liquid and gas phase, using operando molecular spectroscopy techniques. Consejo Nacional de Investigaciones Científicas y Técnicas Universidad Nacional del Litoral

Published
2016

26. Estudio de reacciones catalíticas en la interfase líquido/sólido por espectroscopía infrarroja operando

Author

Aguirre, Alejo, Berli, Claudio Luis Alberto, and Collins, Sebastián Enrique

Subjects
Ingeniería Química, adsorción y oxidación de CO, purl.org/becyt/ford/2.4 [https], ATR, reacción superficial, transporte de masa, FTIR, purl.org/becyt/ford/2 [https], Otras Ingeniería Química, catálisis, INGENIERÍAS Y TECNOLOGÍAS, Micro-reactores
Abstract

La espectroscopia infrarroja en modo de reflexión total atenuada (ATR-IR) es unaherramienta poderosa para investigar mecanismos de reacción en sistemaslíquido(reactivo)/sólido(catalizador). Normalmente, los catalizadores se depositansobre un elemento reflexión interna (IRE) como película o capas de polvo, y sonexpuestos a los reactivos en fase líquida. Para obtener información cuantitativasobre velocidades de reacción, se deben evaluar los aspectos de ingeniería químicade una celda de ATR de flujo pasante. En particular, el transporte de masa dentrode la celda se debe caracterizar. Se presenta aquí un análisis de la transferencia demasa desde la solución hacia la superficie del cristal de ATR donde se deposita elcatalizador. Se desarrollaron criterios para determinar los parámetros cinéticosbajo control químico sobre la base de los número adimensionales de Péclet (Pe),Damköhler (Da) y Biot (Bi) para una película no porosa; y número de Sherwood(Sh) y módulo de Thiele (cl) para una capa de catalizador poroso. Se utilizó unapelícula delgada de Pt depositado sobre un IRE de ZnSe por deposición física devapor y una capa de catalizador poroso de Pt/Al2O3, para estudiar la adsorción yoxidación de monóxido de carbono en fase acuosa. Los datos experimentales de laevolución de la señal a 2048 cm-1 de CO adsorbido sobre platino se ajustaronutilizando un modelo microcinético para obtener constantes de reacción. Losresultados reportados aquí sirven como una guía práctica para determinar loslímites de operación de una celda ATR para estudios in situ y operando. Fil: Aguirre, Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Berli, Claudio Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Collins, Sebastián Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

Published
2015

27. General framework for automated manufacturing systems: multiple hoists scheduling solution

Author

Aguirre, Alejo, Mendez, Carlos Alberto, García Sanchez, Alvaro, Ortega Mier, Miguel, and Castro, Pedro

Subjects
Ingeniería Química, purl.org/becyt/ford/2.4 [https], purl.org/becyt/ford/2 [https], Ingeniería de Procesos Químicos, HOIST SCHEDULING, INGENIERÍAS Y TECNOLOGÍAS, OPTIMIZATION, MILP APPROACH
Abstract

This work presents a generic MILP-based framework for the scheduling of Hoist transportation devices in a complex Automated Manufacturing System. The main contribution of this approach relies on the possibility to tackle multiple hoists in a multiproduct multistage batch process under different production schemes considering: heterogeneous production recipes, multiple units per production stage, possible recycle flows, sequence-dependent transfers and flexible processing times. The effectiveness of this approach was tested in a real industrial application example which was solved with acceptable computational effort. Fil: Aguirre, Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina Fil: Mendez, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina Fil: García Sanchez, Alvaro. Universidad Politecnica de Madrid; España Fil: Ortega Mier, Miguel. Universidad Politecnica de Madrid; España Fil: Castro, Pedro. UMOSE; Portugal

Published
2013

29. Reversible deactivation of a Au/Ce0.62Zr0.38O2 catalyst in CO oxidation: A systematic study of CO2-triggered carbonate inhibition.

Author

del Río, Eloy, Collins, Sebastián E., Aguirre, Alejo, Xiaowei Chen, Juan Jose Delgado, Jose Juan Calvino, and Bernal, Serafín

Subjects
*OXIDATION of carbon monoxide, *ALUMINUM catalysts, *CARBONATES, *CATALYST supports, *ISOTOPIC analysis, *REACTIVE oxygen species, *INFRARED spectroscopy
Abstract

Highly active supported gold catalysts frequently undergo substantial decrease in activity due to deactivation. The aim of this paper is to investigate a reversible inhibition phenomenon of the CO oxidation in an Au/Ce0.62Zr0.38O2 (Au/CZ) catalyst. The results of a systematic study of CO oxidation conditions (CO, O2, and CO2) are discussed. By identifying CO2 as an Au/CZ poison using isotopic transient analysis (13CO/12CO2), we also investigate the origin of inhibition activity by transient and modulated infrared spectroscopy in DRIFT mode. Results demonstrate that carbonate species are formed by reaction of CO2 with reactive lattice oxygen at the metal-support interphase, which in turn inhibits the replenishment of the vacancies by molecular oxygen. A microkinetic model that accounts for the reaction mechanism and inhibition by CO2 is proposed. [ABSTRACT FROM AUTHOR]

Published
2014
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30. Monitoring Reaction Intermediates in Plasma-Driven SO 2 , NO, and NO 2 Remediation Chemistry Using In Situ SERS Spectroscopy.

Author

Li S, Zhao B, Aguirre A, Wang Y, Li R, Yang S, Aravind I, Cai Z, Chen R, Jensen L, and Cronin SB

Abstract

In situ surface-enhanced Raman scattering (SERS) spectroscopy is used to identify the key reaction intermediates during the plasma-based removal of NO and SO 2 under dry and wet conditions on Ag nanoparticles. Density functional theory (DFT) calculations are used to confirm the experimental observations by calculating the vibrational modes of the surface-bound intermediate species. Here, we provide spectroscopic evidence that the wet plasma increases the SO 2 and the NO x removal through the formation of highly reactive OH radicals, driving the reactions to H 2 SO 4 and HNO 3 , respectively. We observed the formation of SO 3 and SO 4 species in the SO 2 wet-plasma-driven remediation, while in the dry plasma, we only identified SO 3 adsorbed on the Ag surface. During the removal of NO in the dry and wet plasma, both NO 2 and NO 3 species were observed on the Ag surface; however, the concentration of NO 3 species was enhanced under wet-plasma conditions. By closing the loop between the experimental and DFT-calculated spectra, we identified not only the adsorbed species associated with each peak in the SERS spectra but also their orientation and adsorption site, providing a detailed atomistic picture of the chemical reaction pathway and surface interaction chemistry.

Published
2021
Full Text
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