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NiO-CaO materials as promising catalysts for hydrogen production through carbon dioxide capture and subsequent dry methane reforming

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Journal of Energy Chemistry 2017年第5期26卷 942-947页

作者： Alejandra Cruz-Hernández J.Arturo Mendoza-Nieto Heriberto Pfeiffer laboratorio de fisicoquímica y Reactividad de superficies(LaFReS) Instituto de Investigaciones en MaterialesUniversidad Nacional Autónoma de MéxicoCircuito exterior s/nCiudad UniversitariaDel.CoyoacánCP 04510Ciudad de MéxicoMexico

In this work, CaO-NiO mixed oxide powders were evaluated as consecutive CO;chemisorbents and catalytic materials for hydrogen production thought the CH;reforming process. Between the NiO impregnated CaO and CaO-NiO mechanical composite, the first one presented better chemical behaviors during the CO;capture and CH;reforming processes, obtaining syngas（H;+ CO） as final product. Results showed that syngas was produced at two different temperature ranges, between 400 and 600 °C and at T > 800 °C, where the first temperature range corresponds to the CH;reforming process but the second temperature range was attributed to a different catalytic reaction process: CH;partial oxidation. These results were confirmed through different isothermal and cyclic experiments as well as by XRD analysis of the final catalytic products, where the nickel reduction was evidenced. Moreover, when a CO-O;flow was used during the carbonation process a triple process was achieved:（i） CO oxidation,（ii） CO;chemisorption and（iii） CH;reforming. Using this gas flow the hydrogen production was always higher than that obtained with CO;.

关键词： Methane reforming CO2 capture Calcium oxide H2 production NiO supported

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Synthesis and evaluation as CO2 chemisorbent of the Li5(Al1-xFex)O4 solid solution materials:Effect of oxygen addition

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Journal of Energy Chemistry 2017年第5期26卷 948-955页

作者： Paulina Olavarría Elizabeth Vera Enrique J.Lima Heriberto Pfeiffer laboratorio de fisicoquímica y Reactividad de superficies(LaFReS) Instituto de Investigaciones en MaterialesUniversidad Nacional Autońoma de MexicoCircuito exterior s/nCd.UniversitariaDel.Coyoacan C.P.04510Ciudad de MéxicoMexico

Pentalithium aluminate（β-LiAlO） and the corresponding iron-containing solid solution(Li(AlFe)O)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, Nadsorption-desorption and temperature-programmed desorption of CO. Results showed that 30 mol% of iron can be incorporated into the β-LiAlOcrystalline structure at aluminum positions. Moreover, iron addition induced morphological and superficial reactivity variations. Li(AlFe)Osamples chemisorbed CObetween 200 and 700 °C, where the superficial chemisorption presented the highest enhancement,in comparison to β-LiAlO. Additionally, Li(AlFe)Osamples sintered at higher temperatures thanβ-LiAlO. Isothermal COchemisorption experiments of β-LiAlOand Li(AlFe)Owere fitted to a first order reaction model, corroborating that iron enhances the COchemisorption, kinetically. When oxygen was added to the gas flow, COchemisorption process was mainly enhanced between 400 and 600 °C for the Li(AlFe)Osample in comparison to β-LiAlO. Hence, Li(AlFe)Osolid solution presented an enhanced COchemisorption process, in the presence and absence of oxygen, in comparison to β-LiAlO.

关键词： Lithium aluminate CO2 chemisorption Solid solution Thermogravimetry

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Thermokinetic and conductivity analyzes of the high CO2 chemisorption on Li5AlO4 and alkaline carbonate impregnated Li5AlO4 samples:Effects produced by the use of CO2 partial pressures and oxygen addition

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Journal of Energy Chemistry 2017年第5期26卷 919-926页

作者： Pedro Sánchez-Camacho J.Francisco Gómez-García Heriberto Pfeiffer laboratorio de fisicoquímica y Reactividad de superficies(LaFReS) Instituto de Investigaciones en MaterialesUniversidad Nacional Autońoma de MexicoCircuito exterior s/nCd.UniversitariaDel.Coyoacan C.P.04510Ciudad de Me´xicoMexico

The effect of COpartial pressure was evaluated during the COchemisorption in penta lithium aluminate（LiAlO）, using different COand Opartial pressures in the presence or absence of alkaline carbonates. Results showed that using low PO（0.1） did not affect the kinetic and final COchemisorption process. Moreover, small additions of oxygen（PO= 0.05） into the mixture flue gas, seemed to increase the COchemisorption. Additionally, the presence of alkaline carbonates modified the COcapture temperature range. COchemisorption kinetic parameters were determined assuming a double exponential model where direct COchemisorption and COchemisorption controlled by diffusion processes are ***, ionic diffusion was analyzed by ionic conduction analysis, where all the gravimetric and ionic measurements were in good agreement showing different diffusion processes depending on ***, the oxygen and alkaline carbonate additions have positive effects during the COchemisorption process in LiAlO, and a possible reaction mechanism is presented.

关键词： CO2 capture Thermogravimetric analysis Partial pressure Ionic conduction

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Structural evolution and reaction mechanism of lithium nickelate(LiNiO_(2))during the carbonation reaction

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Journal of Materiomics 2018年第1期4卷 56-61页

作者： Daniela Gonzalez-Varela Brenda Alcantar-Vazquez Heriberto Pfeiffer laboratorio de fisicoquímica y Reactividad de superficies(LaFReS) Instituto de Investigaciones en MaterialesUniversidad Nacional Autonoma de MexicoCircuito exterior s/nCUDel.CoyoacanCP 04510Ciudad de MexicoMexico Instituto de Ingenieria Coordinacion de Ingeniería AmbientalUniversidad Nacional Autonoma de MexicoCircuito Escolar s/nCUDel.CoyoacanCP 04510Ciudad de MexicoMexico

Lithium nickelate(LiNiO_(2))was synthesized using the lithium excess method,and then characterized by X-ray diffraction,scanning electron microscopy and N_(2) ***,differential thermal and thermogravimetric analyses were performed in CO_(2)presence,at high *** show that LiNiO_(2)is able to react with CO_(2)through a complex structural evolution process,where lithium atoms are released to produce Li_(2)CO_(3),while some nickel atoms are rearranged on different Li_(1-x)Ni_(1+x)O_(2)crystalline ***_(2)-CO_(2)reaction kinetic parameters were determined assuming a first-order reaction,where kinetic constants tended to increase as a function of ***,kinetic constant values did not follow a linear *** atypical behavior was attributed to LiNiO_(2)sintering and crystalline evolution performed as a function of temperature.

关键词： Lithium nickelate CO_(2)chemisorption Lithium diffusion coefficient Phase transition

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Application of 3A Zeolite Prepared from Venezuelan Kaolin for Removal of Pb (II) from Wastewater and Its determination by Flame Atomic Absorption Spectrometry

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American Journal of Analytical Chemistry 2013年第10期4卷 584-593页

作者： Wendy Rondón David Freire Zully de Benzo Angela B. Sifontes Yorbin González Maribel Valero Joaquín L. Brito laboratorio de Espectroscopia Molecular Facultad de Ciencias Universidad de Los Andes Mérida Venezuela laboratorio de fisicoquímica de superficies Centro de Química Instituto Venezolano de Investigaciones Científicas IVIC Caracas Venezuela laboratorio de Química Analítica Centro de Química Instituto Venezolano de Investigaciones Científicas IVIC Caracas Venezuela

This work consists in the use of a 3A zeolite (K-LTA) obtained by a process of exchange of sodium for potassium (4A zeolite), synthesized from Venezuelan kaolin for the removal of Pb (II) ions from aqueous solutions by batch process mode in order to consider its application in treating industrial wastewaters. The 3A zeolite was characterized for X-ray powder diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX). The metal concentration in the equilibrium Ce (mg·L-1) after adsorption with 3A zeolite was analyzed using flame atomic absorption spectrometry (FAAS). The influences of the solution pH, contact time, metal initial concentration and adsorbent dosage have been studied. The retention of metal occurring at pH values around 6.5 and the adsorption equilibrium was obtained at 60 min. The equilibrium process was well described by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The Langmuir parameters qm (mg·g-1) and b (L·mg-1) (which are related to the sorption capacity and constant of sorption energy) obtained were 14.64 and 5.42 respectively. The Pb (II) experimental uptake was about 14.56 mg·g-1, a little smaller than the theoretical one given by Langmuir isotherm model. The regression parameters and correlation coefficients (R) indicate that the adsorption data for Pb (II) removal fit better the Langmuir isotherm model. Moreover, 0 1/n 1 (1/n is 0.13), indicating that adsorption of metal ions on the zeolite, is a favorable physical process. The application of removing of the metal lead from real samples was examined by industrial wastewater samples. For all samples, the percentage of recovery was found with accuracy of more than 98%. The present work suggests 3A zeolite used as a sorbent material with relatively low cost, obtained from Venezuelan raw material;it is a candidate for removal lead ion and probably other cationic heavy metal species

关键词： Adsorption Wastewater Lead (II) Ion Zeolite Langmuir Isotherm FAAS

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