130 research outputs found
Nanoporous Materials and Their Applications
This book is a special collection of articles dedicated to the preparation and characterization of nanoporous materials, such as zeolitic-type materials, mesoporous silica (SBA-15, MCM-41, and KIT-6), mesoporous metallic oxides, metal–organic framework structures (MOFs), and pillared clays, and their applications in adsorption, catalysis, and separation processes. This book presents a global vision of researchers from international universities, research centers, and industries working with nanoporous materials and shares the latest results on the synthesis and characterization of such materials, which have given rise to the special interest in their applications in basic and industrial processes
The influence of ethanol-assisted washes to obtain swollen and pillared MWW-type zeolite with high degree ordering of lamellar structure
[EN] We studied the influence of the ethanol used as a washing solvent for obtaining swollen and pillared MWW topology zeolites with long-range ordering of lamellar structure. The diffractogram results showed that the increased number of washes increases the degree of order of the lamellar structure. Thermogravimetric results showed a considerable removal of the weakly interacting surfactant molecules after the third wash. The washes with ethanol did not remove the surfactant that strongly interacted with the MWW structure. The pillared material after the third wash showed a long-range ordering of the lamellar structure with the surface area of 728 m(2) g(-1), mesopore sizes of 2-4 nm and morphology characteristic of pillared MWW-type zeolites.Anderson Joel Schwanke is grateful the CAPES Foundation and PDSE program (process number 99999.004779/2014-02). Urbano Diaz acknowledges to the Spanish Government (MAT2014-52085-C2-1-P and MAT2017-82288-C2-1-P).Schwanke, AJ.; Díaz Morales, UM.; Corma Canós, A.; Pergher, S. (2019). The influence of ethanol-assisted washes to obtain swollen and pillared MWW-type zeolite with high degree ordering of lamellar structure. Microporous and Mesoporous Materials. 275:26-30. https://doi.org/10.1016/j.micromeso.2018.08.010S263027
The influence of swelling agents molecular dimensions on lamellar morphology of MWW-type zeolites active for fructose conversion
[EN] A new route to obtain pillared, disordered or desilicated MWW-type zeolites was developed assisted by quaternary ammonium surfactants with different hydrocarbon tail size acting as swelling agents (C(12)TA(+), C(I6)TA(+), C(18)TA(+)) and TPA(+) both exchanged to their hydroxide forms instead of only one swelling agent (C(n)TA(+) or TPA(+)) in hydroxide form. Effect of surfactant concentration and swelling conditions were determinant to obtain MWW-type zeolites with different lamellar organization and spatial distribution of individual zeolitic layers. Specifically, soft swelling at 25 degrees C with C(12)TA(+) preserved layer structure reaching a final disordered/pillared structure while pillared structures are obtained in the case of materials swollen with C(16)TA(+) and C(18)TA(+). Aggressive swelling processes at 80 degrees C favored desilication, damaging the layers structure in case of C(12)TA(+) while pillared materials are obtained after swollen with C(16)TA(+) and C(18)TA(+) surfactants. It was proved that both swelling agents in hydroxide forms combining with swelling and pillaring procedure influenced on physico-chemical and morphological nature of MWW-type materials due to the particular conditions used. The obtained derivative MWW zeolites with different morphology, order and accessibility levels were firstly evaluated by catalytic dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) showing superior activity compared to beta zeolites reported in literature.Anderson Joel Schwanke is grateful to CAPES Foundation and PDSE program (process number 99999.004779/2014-02) from Ministry of Education of Brazil. U.D and A.C acknowledge to the Spanish Government (Severo Ochoa program SEV-2012-0267 and MAT2014-52085-C2-1-P) and to the Generalitat Valenciana (Prometeo 11/2013-011) by the funding. The European Union is also acknowledged by ERC-AdG-2014-671093 - SynCatMatch.Schwanke, AJ.; Pergher, S.; Díaz Morales, UM.; Corma Canós, A. (2017). The influence of swelling agents molecular dimensions on lamellar morphology of MWW-type zeolites active for fructose conversion. Microporous and Mesoporous Materials. 254:17-27. https://doi.org/10.1016/j.micromeso.2016.11.007S172725
Estudo da síntese da zeólita MCM-71
A new kind of material, denominated MCM-71, was synthesized and characterized by several complementary techniques: X Ray Diffractometry, textural analysis by nitrogen adsorption, Scanning electronic microscopy and infrared spectroscopy. MCM-71 zeolite was successfully synthesized by hydrothermal synthesis in the presence of triethanolamine. Mordenite phase as impurity was not detected, otherwise quartz was observed. The MCM-71 sample obtained presented a BET surface area of 20 m²/g in the as synthesized form and of 85 m²/g in protonic form. By SEM was observed crystals with rectangular shape with average size of 2 x 0,2 x 0,05 µm and this crystals were agglomerated in spherical particles with average diameter between 14 and 24 µm
Production of Solketal Using Acid Zeolites as Catalysts
Commercial solketal is known as Augeo™ SL 191 and is produced by Rhodia (a member of the Solvay Group), which stands out as a slow evaporation solvent derived from glycerin which is considered a renewable source. It has low toxicity to human health and the environment. It is a good solvent for resins and polymers, replacing solvents derived from petroleum, and can be used as an additive of (bio) fuels. This work aimed to study acidy zeolites (H-BEA, H-MOR, H-MFI, and H-FER) as new heterogeneous catalysts of solketal production, through the ketalization reaction of glycerol with acetone. The catalytic activity showed H-BEA > H-MOR = H-MFI > H-FER after 180 min, in kinetics study. The major conversion was 85% for H-BEA. It was also verified that all the catalysts can be reused four times without washing or pretreatment among reactions in batch reactor. The solketal produced in this work was characterized by comparing it with its commercial standard, obtaining very similar characteristics
Caracterização de argilas bentonitas e diatomitas e sua aplicação como adsorventes
Five samples of natural clays denominated: diatomite, CN-20, CN-29, CN-40 and CN-45 from Aliança Latina LTDA were characterized by differents supplementary techniques such as: XRD, chemical analysis, adsorption N2 measurements, infrared spectroscopy analysis, thermogravimetric analysis. Clays were tested in adsorption of blue methylene. All of isotherms adjust in a model of physics adsorption with formation of multilayers, however in the case of diatomite was a favorable adsorption (type II) and the CNs were a not favorable adsorption (type III). In the case of CNs had flocculation of clay in high concentration of coloring
A Lamellar MWW Zeolite With Silicon and Niobium Oxide Pillars: A Catalyst for the Oxidation of Volatile Organic Compounds
This is the peer reviewed version of the following article: A. J. Schwanke, R. Balzer, C. Wittee Lopes, D. Motta Meira, U. Díaz, A. Corma, S. Pergher, Chem. Eur. J. 2020, 26, 10459, which has been published in final form at https://doi.org/10.1002/chem.202000862. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] In this work, an MWW-type zeolite with pillars containing silicon and niobium oxide was synthesized to obtain a hierarchical zeolite. The effect of niobium insertion in the pillaring process was determined by combining a controllable acidity and accessibility in the final material. All pillared materials had niobium occupying framework positions in pillars and extra-framework positions. The pillared material, Pil-Nb-4.5 with 4.5 wt % niobium, did not compromise the mesoporosity formed by pillaring, while the increase of niobium in the structure gradually decreased the mesoporosity and ordering of lamellar stacking. The morphology of the pillared zeolites and the niobium content were found to directly affect the catalytic activity. Specifically, we report on the activity of the MWW-type zeolites with niobium catalyzing the gas-phase oxidation of volatile organic compounds (VOCs), which is an important reaction for clean environmental. All produced MWW-type zeolites with niobium were catalytically active, even at low temperatures and low niobium loading, and provided excellent conversion efficiencies.A.J.S. thanks the CordenacAo de Aperfeicoamento de Pessoal de Nivel Superior-Brasil (CAPES)-Finance Code 001, the PDSE program (process number 99999.004779/2014-02) and the prof. Claudio Radtke from the PPGQ-UFRGS for the XPS analyses. C.W.L. is grateful to INOMAT/CAPES for a postdoctoral fellowship. U.D. thanks the funding by the Spanish Government (MAT2017-82288-C2-1-P).Schwanke, AJ.; Balzer, R.; Lopes, CW.; Meira, DM.; Díaz Morales, UM.; Corma Canós, A.; Pergher, S. (2020). A Lamellar MWW Zeolite With Silicon and Niobium Oxide Pillars: A Catalyst for the Oxidation of Volatile Organic Compounds. Chemistry - A European Journal. 26(46):1-12. https://doi.org/10.1002/chem.202000862S1122646Zhang, X., Guo, J., Guan, P., Liu, C., Huang, H., Xue, F., … Chisholm, M. F. (2013). Catalytically active single-atom niobium in graphitic layers. Nature Communications, 4(1). doi:10.1038/ncomms2929Yan, W., Zhang, G., Yan, H., Liu, Y., Chen, X., Feng, X., … Yang, C. (2018). Liquid-Phase Epoxidation of Light Olefins over W and Nb Nanocatalysts. ACS Sustainable Chemistry & Engineering, 6(4), 4423-4452. doi:10.1021/acssuschemeng.7b03101Ziolek, M., & Sobczak, I. (2017). The role of niobium component in heterogeneous catalysts. 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Compósitos magnéticos baseados em hidrotalcitas para a remoção de contaminantes aniônicos em água
Estudo da adsorção de compostos sulfurados empregando zeólitas contendo zinco
This paper deals with an adosrption of sulphur compounds employing zeolites containing zinc. The zeolites employed were commercial NaY and Beta. The zinc was incorporated in three levels: 0.5; 1.0 and 5%. The sulphur compounds studied were benzothiophene and dibenzothiofene. The results showed that both zeolites can be employed for adsorption of benzothiophene and dibenzothiophene. The Zn incorporation (0.5%) promotes an increase in zeolites adsorption ability. The DBT adsorbs more than BT, probably because it strongly interacts with zeolite structure. The BT adsorbs more in NaY than in beta probably because the NaY zeolite has a high intern volume. This is not observed for DBT
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