Search results for "mesoporous material"
showing 10 items of 262 documents
Hydrogenation of Aromatics in Diesel Fuels on Pt/MCM-41 Catalysts
1997
Abstract The hydrogenation activity of Pt supported on two mesoporous MCM-41 samples differing in their chemical composition has been studied by following the kinetics of the hydrogenation of naphthalene at 225–275°C reaction temperature and 5.0 MPa total pressure and by comparing the kinetic parameters obtained with Pt supported on a mesoporous amorphous silica-alumina (MSA) and other conventional supports, such as commercial amorphous silica-alumina (ASA), zeolite USY, γ-alumina, and silica. The two mesoporous MCM-41 and MSA materials having very high surface areas allowed for a better dispersion of the Pt particles, and they showed a superior overall hydrogenation activity as compared to…
Adsorption of Rare Earth Elements onto DNA-Functionalized Mesoporous Carbon.
2020
The recovery and separation of rare earth elements (REEs) are of national importance owing to the specific usages, high demand, and low supply of these elements. In this research, we have investigated the adsorption of rare earth elements onto DNA-functionalized mesoporous carbons with a BET surface area of 605 m2/g and a median mesopore width of 48 A. Three types of single-stranded DNA, one with 100 base units of thymine, another with 20 units of thymine, and the third, a 2000 unit long DNA from salmon milt were grafted on the carboxylated mesoporous carbon surface. All of the DNA-functionalized mesoporous carbons demonstrated higher adsorption of REEs compared to pristine mesoporous carbo…
Chemisorption of Atomically Precise 42-Carbon Graphene Quantum Dots on Metal Oxide Films Greatly Accelerates Interfacial Electron Transfer
2019
Graphene quantum dots (GQDs) are emerging as environmentally friendly, low-cost, and highly tunable building blocks in solar energy conversion architectures, such as solar (fuel) cells. Specifically, GQDs constitute a promising alternative for organometallic dyes in sensitized oxide systems. Current sensitized solar cells employing atomically precise GQDs are based on physisorbed sensitizers, with typically limited efficiencies. Chemisorption has been pointed out as a solution to boost photoconversion efficiencies, by allowing improved control over sensitizer surface coverage and sensitizer-oxide coupling strength. Here, employing time-resolved THz spectroscopy, we demonstrate that chemisor…
Obtaining of the Modified NH4NO3 Granules with 3-D Nanoporous Structure: Impact of Humidifier Type on the Granule’s Structure
2018
The article deals with the study of the porous ammonium nitrate granules’ (PAN) nanoporous structure of surface and surface layers. The research results, presented in the article, show that the suggested way to generate PAN allows to provide the granule porous structure without destruction of core and disposal of air from the granules. Analysis of experiments results has shown that various types of humidifiers can form various kinds of pores after drying – “mechanical” pores and “modification” pores. Various types of humidifiers have significant effect on the ratio of values of “mechanical” and “modification” pores. The obtained results allow to select the optimal humidifier composition, wh…
De novo synthesis of mesoporous photoactive titanium(IV)-organic frameworks with MIL-100 topology
2019
[EN] Most developments in the chemistry and applications of metal-organic frameworks (MOFs) have been made possible thanks to the value of reticular chemistry in guiding the unlimited combination of organic connectors and secondary building units (SBUs) into targeted architectures. However, the development of new titanium-frameworks still remains limited by the difficulties in controlling the formation of persistent Ti-SBUs with predetermined directionality amenable to the isoreticular approach. Here we report the synthesis of a mesoporous Ti-MOF displaying a MIL-100 topology. MIL-100(Ti) combines excellent chemical stability and mesoporosity, intrinsic to this archetypical family of porous…
Immobilization of copper complexes with (1,10-phenanthrolinyl)phosphonates on titania supports for sustainable catalysis
2017
Different strategies for the immobilization of copper complexes with 1,10-phenanthroline (phen) using the phosphonate anchoring group were investigated to prepare robust and porous heterogeneous catalysts. Homoleptic and heteroleptic copper(I) complexes with phen bearing the bis(trimethylsiloxy)phosphoryl anchoring group (Pphen-Si) at different positions of the phen backbone were prepared and covalently incorporated into titania (TiO2) xerogels by using the sol–gel process or grafted onto the surface of mesoporous TiO2 (SBET = 650 m2 g−1). Copper(I) bis(Pphen-Si) complexes were the only complexes that were successfully anchored onto the TiO2 surface because the heterogenization was often ac…
Robust Mesoporous CoMo/γ-Al2O3 Catalysts from Cyclodextrin-Based Supramolecular Assemblies for Hydrothermal Processing of Microalgae: Effect of the P…
2018
Hydrothermal liquefaction (HTL) is a promising technology for the production of biocrude oil from microalgae. Although this catalyst-free technology is efficient under high-temperature and high-pressure conditions, the biocrude yield and quality can be further improved by using heterogeneous catalysts. The design of robust catalysts that preserve their performance under hydrothermal conditions will be therefore very important in the development of biorefinery technologies. In this work, we describe two different synthetic routes (i.e., impregnation and cyclodextrin-assisted one-pot colloidal approach), for the preparation in aqueous phase of six high surface area CoMo/γ-Al2O3 catalysts. Cat…
A comparative study of photocatalytically active nanocrystalline tetragonal T zyrcon- type and monoclinic scheelite-type bismuth vanadate
2018
The authors from Vinča Institute of Nuclear Sciences acknowledge the financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project no: 172056 ). The work of K. Smits was supported by Latvian National Research Program IMIS2 (Grant no. 302/2012 ).
Not always what closes best opens better: mesoporous nanoparticles capped with organic gates
2019
ABSTRACT Four types of calcined MCM-41 silica nanoparticles, loaded with dyes and capped with different gating ensembles are prepared and characterized. N1 and N2 nanoparticles are loaded with rhodamine 6G and capped with bulky poly(ethylene glycol) derivatives bearing ester groups (1 and 2). N3-N4 nanoparticles are loaded with sulforhodamine B and capped with self-immolative derivatives bearing ester moieties. In the absence of esterase enzyme negligible cargo release from N1, N3 and N4 nanoparticles is observed whereas a remarkable release for N2 is obtained most likely due to the formation of an irregular coating on the outer surface of the nanoparticles. In contrast, a marked delivery i…
Synthesis and characterisation of ordered arrays of mesoporous carbon nanofibres
2009
A facile and reproducible one-step pathway has been developed for preparing ordered arrays of mesoporous carbon nanostructures within the pores of anodized aluminium oxide (AAO) membranes, through the confined self-assembly of phenol/formaldehyde resol and amphiphilic copolymer templates. The morphology of the mesoporous carbon nanostructures can be controlled by varying the copolymer surfactant, the quantity of the resol–surfactant precursor sol used and the amount of phenol–formaldehyde resol introduced into the resol–surfactant sol. One-dimensional (1-D) carbon nanostructures, such as carbon fibres with a core–shell structure and carbon ribbons with circular mesopores running parallel to…