0000000000048476
AUTHOR
Alaina Moragues
showing 10 related works from this author
New multicomponent catalysts for the selective aerobic oxidative condensation of benzylamine to N-benzylidenebenzylamine
2014
Aerobic oxidative condensation of benzylamine to N-benzylidenebenzylamine was carried out on new gold-based catalysts using as support bimodal UVM-7-like mesoporous silica containing Ni and Ce (or Sn) as oxide nanodomains partially embedded inside the mesoporous UVM-7 silica walls. These nanodomains acted as effective and stable inorganic anchors favoring the nucleation, growth and stability of supported gold particles. Following the atrane method (a “one-pot” strategy able to harmonize the hydrolytic reactivity of different heteroelements through the use of complexes containing triethanolamine-derived ligands (atranes) as precursors) the stability of the oxide nanodomains during oxidation …
Mesoporous iron phosphate/phosphonate hybrid materials
2014
Abstract Relatively high surface area pure mesoporous iron-phosphorus oxide-based derivatives have been synthesized through an S + I − surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from iron atrane complexes and phosphoric and phosphonic acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from iron phosphate up to hybrids involving approximately 30% of organophosphorus entities (phosphonates or diphosphonates). X-ray powder diffraction, transmission elect…
Enlarged pore size in nanoparticulated bimodal porous silicas: Improving accessibility
2016
Abstract Mass-transfer kinetics seems to be highly favored in siliceous materials constructed from the aggregation of mesoporous nanoparticles. Besides intra-particle mesopores, over the course of the aggregation process an inter-particle (textural) large pore system is generated. Diffusion constrains through the resulting hierarchically structured pore systems mainly depend on the characteristics of the intra-particle mesopores. By using alkanes as swelling agents, we have been able to significantly increase the intra-particle mesopore size in previously well characterized UVM-7 materials. The Winsor-III-like behavior associated with the presence of alkanes in the hydro-alcoholic reaction …
Understanding the role of Ti-rich domains in the stabilization of gold nanoparticles on mesoporous silica-based catalysts
2018
3 Tablae, 14 Figures.-- Supplementary material.-- © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Selective hydrogenation of nitroderivatives over Au/TiO2/UVM-7 composite catalyst
2020
Abstract Hydrogenation of nitroderivatives (4-nitrostyrene or 7-nitro-1-tetralone) was performed using as support a silica mesoporous material with high specific surface area (1091 m2/g) and a bimodal pore size distribution (UVM-7). Gold and/or TiO2 were deposited inside the pores of this support with the aim to achieve high activity and selectivity for this reaction. The morphology and structure of the powders have been characterized by adsorption-desorption isotherms, XRD, TEM, STEM-HAADF, XPS and ATR-FTIR. Structural characterizations shown differences between the catalysts with and without titania. The presence of TiO2 provides a better size distribution of the spherical gold nanopartic…
Heterogeneous Gold Catalyst: Synthesis, Characterization, and Application in 1,4-Addition of Boronic Acids to Enones
2015
The new 1 wt % Au/TiO2–UVM-7 catalyst was prepared and fully characterized. This heterogeneous catalyst proved to be active, selective and recyclable for the unprecedented gold-catalyzed 1,4-addition of various functionalized arylboronic acids to 2-cyclohexen-1-one and other selected enones using toluene as a solvent. The gold-based catalyst was recycled two times and played an active role in this reaction, and the nature of the solvent determined a remarkable change in the products’ selectivities.
High-Temperature Stable Gold Nanoparticle Catalysts for Application under Severe Conditions: The Role of TiO2 Nanodomains in Structure and Activity
2015
Metal nanoparticles with precisely controlled size are highly attractive for heterogeneous catalysis. However, their poor thermal stability remains a major concern in their application at realistic operating conditions. This paper demonstrates the possibility of synthesizing gold nanoparticles with exceptional thermal stability. This has been achieved by using a simple conventional deposition–precipitation technique. The material employed as catalyst consists of gold supported on a TiO2-impregnated SiO2 bimodal mesoporous support. The resulting material shows gold nanoparticles with a narrow size distribution around 3.0 nm, homogeneously dispersed over the TiO2/SiO2 material. Most interesti…
Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hy…
2016
Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and …
The different catalytic behaviour in the propane total oxidation of cobalt and manganese oxides prepared by a wet combustion procedure
2013
Abstract Cobalt oxide and manganese oxide catalysts have been prepared through aqueous synthesis using a wet combustion procedure. These materials have been tested as catalysts for the total oxidation of propane. It has been observed a different catalytic behaviour between cobalt and manganese oxides although for both oxides a very high catalytic activity has been obtained. Cobalt oxides prepared by the wet combustion procedure are less reactive than a simple cobalt oxide prepared without the addition of organic acids. However, in the case of manganese oxide the use of organic acids highly increases the catalytic activity. The different catalytic behaviour has been related to the variation …
Low-Cost Synthesis of Bimodal Mesoporous Silica-Based Materials by Pseudomorphic Transformation.
2015
Nanoparticulate bimodal porous silica-based materials have been prepared through a surfactant-assisted procedure by using a simple template and starting from inexpensive sodium silicate as silicon source. Different procedural variables, such as pH or the nature and concentration of the surfactant, have been explored to optimize the preparative protocol, which allows, in turn, improved understanding of the formation process. The final bulk materials (called UVM-10 or M-UVM-10) are formed by pseudomorphic transformation of fresh silica-based xerogels under mild basic conditions. The UVM-10 architecture is constructed from small mesoporous nanoparticles, the aggregation of which generates a di…