Bentonite functionalized with propyl sulfonic acid groups used as catalyst in esterification reactions

AbstractThe main objective of this work is the functionalization of bentonite from the Amazon (region) by the grafting of propyl sulfonic acid groups to catalyze the esterification reaction of acetic acid and 1-propanol. Functionalization was accomplished by anchoring, oxidation and acid activation of (3-mercaptopropyl)trimethoxysilane, (MTPS). The procedure gave acid properties to the raw bentonite. This material, acting as a catalyst, increased the reaction speed and improved the yield by about 12% compared to the uncatalyzed reaction. The functionalized bentonite was characterized by XRD, TG/DTA, FTIR, N2 adsorption/desorption at 77K and XRF, and the surface acidity was determined by titration

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Efficient esterification of eugenol using a microwave-activated waste kaolin

Abstract: Eugenyl acetate has been investigated because of its beneficial bioactive antioxidant, antimicrobial and potential properties against the development of Aedes aegypti larvae. Here, we report, for the first time, the use of a catalyst prepared from flint kaolin with microwave irradiation for the acetylation of eugenol. A few kinetic parameters were evaluated in the experiments used for eugenol ester synthesis. High conversions (98%) were obtained after 1 h of reaction. The prepared material shows good activity (over 90%) even after 4 cycles of use. Therefore, the use of microwave radiation made it possible to prepare a catalyst in a very short time using a low-cost industrial by-product as a raw material that proved to be highly active, in addition to the additional advantage of being reusable, which would reduce possible environmental impacts caused by its disposal in the environment. Graphic abstract: [Figure not available: see fulltext.]. © 2020, Akadémiai Kiadó, Budapest, Hungary

Valorization of Mining Waste in the Synthesis of Organofunctionalized Aluminosilicates for the Esterification of Waste from Palm Oil Deodorization

The synthesis of aluminosilicate Al-MCM-41 was performed using mining kaolin waste as an alternative source of silicon and aluminum to add value to this waste. In a preliminary stage, acid leaching was carried out with the kaolin residue with three different durations (1, 1.5 and 2 h) to evaluate the leaching time that provided the highest amounts of silicon and aluminum in the tailings. Molecular sieves were synthesized by the hydrothermal method and calcined at 550 °C to eliminate the surfactant. X-ray diffractograms of the synthesized samples revealed that the sample AM41-2H, obtained from kaolin leached for 2 h (MC7-2H), presented the best structural arrangement due to the presence of 2θ angles close to 2.32°, a specific surface area of 1016 m 2 ·g -1 , a pore volume of 0.80 cm 3 ·g -1 , and a pore diameter of 3.14 nm, which are characteristic of Al-MCM-41. A sample of AM41-2H was functionalized with 3-mercaptopropyltrimethoxysilane (MTPS) (5 mmol MTPS/g AM41-2H). To eliminate excess unaltered MTPS on the surface of the material, the functionalized aluminosilicate (AM41-2H-F) was subjected to a purification step. The organic functional group that remained in the molecular sieve (-SH) was then oxidized to its corresponding acid group (-SO 3 H) to form stronger acid sites. Then, the heterogeneous catalyst obtained (AM41-2H-O) was tested in an esterification reaction of oleic acid with methanol and in an esterification reaction of an industrial waste from palm oil refinement (DDPO), which is generated during the deodorization process of palm oil. Both reactions were carried out for 2 h at 130 °C, with a fatty acid/methanol molar ratio of 1:30 and addition of 5% catalyst to the mass of fatty acid. The results obtained revealed that the conversion to esters from oleic acid and DDPO was 99% and 98%, respectively, in contrast to the uncatalyzed reaction, which achieved only 15% conversion. The catalysts used in the reactions were recovered and reused in the same conditions as the initial reactions, which showed conversions in this first cycle of catalyst reuse of 98% for oleic acid and 81% for DDPO, proving the efficiency of the catalyst synthesized from industrial kaolin waste. © Copyright 2019 American Chemical Society