Modification of polyetherimide membranes with ZIFs fillers for CO2 separation

[EN] Flat hybrid membranes composed of polyetherimide (PEI) as matrix and zeolitic imidazolate frameworks (ZIFs) as fillers at concentrations of 10 and 20 wt% were prepared. Apparent permeability coefficient and apparent diffusivity coefficient of gases (CO2 and N-2) for these hybrid membranes (PZIFs) were determined by the "timelag" method. The experimental conditions used were from 25 degrees C to 55 degrees C with pressures of 2, 3 and 5 bar. The PZIFs with fillers of ZIF-8 (PZ-Zn) and ZIF-67 (PZ-Co) showed apparent selectivities (alpha(pa(CO2)/pa(N2))) of 39.6 and 27.5, respectively, higher than the alpha(pa(CO2)/pa(N2)) of the reference membrane PEI, while the membrane with filler of ZIF-Mix (PZ-Zn/Co) showed the lowest alpha(pa(CO2)()/pa(N2)) selectivity of 10.3 in the membrane series (under conditions of 25 degrees C and 2 bar). It is proposed that the selectivity of the membrane series can be attributed to two critical factors: the particle size/distribution ratio in the polymer base and sorption of CO2 at local sites of the bimetallic mixture. On the other hand, gas permeation studies (O-2, CO2 and CH4, and CO2/CH(4 )and CO2/C2H4 mixtures), were carried out in the series of PZIFs membranes. Permeability data were obtained by an isostatic method based on a permeation cell connected in series to a gas chromatograph where the rate of permeated gases was analyzed until a stationary state was reached. The complementary characterization techniques were: scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction, which support the existence of the amorphous/crystalline phases of the PZIFs.This research has been supported by the ENE/2015-69203-R project, granted by the Ministerio de Economia y Competitividad (MINECO), Spain; Also authors are grateful to UNAM-DGAPA-PAPIIT projects IG-100185, and IG-114818. This study was partially supported by the CONACyT (Mexico) projects 2013-05-231461 and CB -2014-01-235840.Vega, J.; Andrio, A.; Lemus, A.; Díaz, J.; Del Castillo, L.; Gavara, R.; Compañ Moreno, V. (2019). Modification of polyetherimide membranes with ZIFs fillers for CO2 separation. Separation and Purification Technology. 212:474-482. https://doi.org/10.1016/j.seppur.2018.11.033S47448221

Conductivity study of Zeolitic Imidazolate Frameworks, Tetrabutylammonium hydroxide doped with Zeolitic Imidazolate Frameworks, and mixed matrix membranes of Polyetherimide/Tetrabutylammonium hydroxide doped with Zeolitic Imidazolate Frameworks for proton conducting applications

[EN] ZIF-8 (Z8), ZIF-67 (Z67), and ZMix, a Zn/Co bimetallic zeolitic imidazolate framework (ZIF), were synthesized and doped with tetrabutylammonium hydroxide (ZIFsT). The obtained powders were used as fillers for polyetherimide (PEI) at a concentration of 20 wt %. The presence of the three ZIFsT in the polymeric matrix enhanced proton transport relative to that observed for PEI or ZIFs alone. The real and imaginary parts of the complex conductivity were obtained for each of the six materials, and the temperature and frequency dependence of the real part was analyzed. The results at different temperatures show that the dc-conductivity are about three orders of magnitude higher for the doped ZIFsT materials than for the PEI/ZIFsT membranes. In addition, the conductivity of the PEI/ZIFsT membranes increases five or six times when the temperature is changed from 25 °C to 55 °C. For these materials, the conductivity measurements have a linear dependency with frequency, which allowed for the creation of a master curve. It was also found that the PEI/ZMixT membrane activation energy is four times smaller than that of PEI/Z8T membranes and five times smaller than that of PEI/Z67T. Similarly, the real and imaginary parts of the complex dielectric constant were obtained, and the tan ¿ was evaluated. Using this value, the diffusion coefficient and the charge carrier density were obtained. A discussion of the proton transport mechanism through the membrane is given, and a comparison of this work with those on similar electrolyte membranes is included.This research has been supported by the ENE/2015-69203-R project, granted by the Ministerio de Economia y Competitividad (MINECO), Spain, and grants from National Mexican Council for Science and Technology for the scholarships of Ph.D. No. 356825 and mixed scholarship 2015 - MZO2016-mobility in the foreigner granted to Jesus Vega Moreno registered scholarship holder number 256015. Thanks to the CONACYT Program for the fellowship at the Universidad Politecnica de Valencia (UPV) and Universitat Jaume I that PhD student Jesus Vega used to carry out the experimental studies of this work. DGAPA-PAPIIT IG-100315.Vega, J.; Andrio, A.; Lemus, AA.; Del Castillo, LF.; Compañ Moreno, V. (2017). Conductivity study of Zeolitic Imidazolate Frameworks, Tetrabutylammonium hydroxide doped with Zeolitic Imidazolate Frameworks, and mixed matrix membranes of Polyetherimide/Tetrabutylammonium hydroxide doped with Zeolitic Imidazolate Frameworks for proton conducting applications. Electrochimica Acta. 258:153-166. https://doi.org/10.1016/j.electacta.2017.10.095S15316625

Producci?n de carne bovina en praderas de pasto estrella (Cynodon nlemfuensis, Vanderyst var nlemfuensis) bajo diferentes presiones de pastoreo y niveles de fertilizaci?n nitrogenada

Tesis (M. Sc) -- CATIE, Turrialba (Costa Rica),1977El presente experimento se realiz? en la Finca Experimental Ganadera del Departamento de Ganader?a Tropical del CATIE, Turrialba, Costa Rica. Los objetivos fueron: evaluar el efecto de pastoreo y fertilizaci?n nitrogenada sobre el comportamiento de las praderas de pasto Estrella Africana (Cynodon nlemfuensis), la Producci?n animal, la compactaci?n, el contenido de nitr?geno, la acidez del suelo y la eficiencia econ?mica. Se estudiaron cinco niveles de presi?n de pastoreo 2, 4, 6, 8 y 10 kg de MON/100 de PV, y cinco niveles de fertilziaci?n nitrogenada 0, 125, 250, 375, y 500 kg de N/ha/a?o. Durante los primeros 112 d?as experimentales hubo efecto (P < 0.01) sobre varios par?metros: conforme aument? la presi?n de pastoreo aument? la disponibilidad de forraje de 2129 a 4763 kg de MON/ha los incrementos diarios de peso de -0.076 a 0.416 kg/animal/d?a, la Producci?n de carne por hect?rea de -2.45 a 3.48 kg/ha/d?a disminuy? el contenido de prote?na cruda de 15.17 a 9.7 por ciento, la digestibilidad in vitro de la MON de 45.46 a 43.78 por ciento la carga animal de 12.30 a 5.59 novillos de 300 kg/ha/d?a. Durante este per?odo tambi?n hubo efecto (P < 0.01) de la fertilizaci?n nitrogenada sobre la tasa de crecimiento del pasto. El an?lisis econ?mico revel? una rentabilidad positiva s?lo con disponibilidades altas de forraje por animal (10 kg de MON/100 kg de PV) y la menor inversi?n posible en insumo

Materials for Hydrogen Storage: Low temperature Structural Transformation in Pillared 2D Solids, T[Ni(CN)4].2pyz, T =Mn, Zn, Cd

The incorporation of pillars in 2D solids allows the preparation of 3D porous materials with tailored cavity size and shape. In this sense, planar coordination polymers based on tetracyanometallates, T[M(CN)4] with T = Mn, Fe, Co, Ni, Cu, Zn, Cd; M = Ni, Pd, Pt, appear as an ideal prototype of 2D solids to be considered. The metal centers at their surface contain available coordination sites which can be used as anchoring positions for the ligands to be used as pillars. Under certain preparative conditions, a fraction of the available metal coordination sites could be maintained free of ligands to allow their interaction with the guest molecule within the cavities. Such possibility provides an ideal system of porous 3D solids for studies related with the hydrogen storage in nanocavities; in fact, two studies in that sense has already been reported [1, 2]. All the studies related with the hydrogen storage in porous solids are carried out under cryogenic conditions, usually at 77 K. For some cyanometallates negative thermal expansion behavior has been reported [3], which could be interpreted as evidence of charge redistribution within the T-N-CM- C-N-T chain on the temperature change, particularly under cryogenic conditions. This suggests that in 2D pillared solids low temperature structural transformation could be present, particularly for pillars of certain flexibility and where the electronic structure of layers and pillars remains strongly coupled. Such possibility is explored in this contribution. As prototype of pillared 2D solids T[Ni(CN)4].2pyz, with pyz = Pyrazine were used

Three structural modifications in the series of layered solids

In the studied series of layered solids, the available coordination sites at T metal centers are occupied by water molecules which serve to stabilize additional water molecules in the interlayer region through hydrogen bonding interactions. The stability of these 2D solids results from these interactions between coordinated and weakly bonded water molecules. In this contribution, the crystal structures and related properties of the titled compounds are reported. Three different structural modifications for a given T metal were found. The refined crystal structures were supported by the recorded infrared, Raman, and UV–vis spectra and thermogravimetric data. Two of these modifications were found to be room and high temperature thermodynamic products and the remaining one a room temperature kinetic product. 2011 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved

Materials for Hydrogen Storage: Low temperature Structural Transformation in Pillared 2D Solids, T[Ni(CN)4].2pyz, T =Mn, Zn, Cd

The incorporation of pillars in 2D solids allows the preparation of 3D porous materials with tailored cavity size and shape. In this sense, planar coordination polymers based on tetracyanometallates, T[M(CN)4] with T = Mn, Fe, Co, Ni, Cu, Zn, Cd; M = Ni, Pd, Pt, appear as an ideal prototype of 2D solids to be considered. The metal centers at their surface contain available coordination sites which can be used as anchoring positions for the ligands to be used as pillars. Under certain preparative conditions, a fraction of the available metal coordination sites could be maintained free of ligands to allow their interaction with the guest molecule within the cavities. Such possibility provides an ideal system of porous 3D solids for studies related with the hydrogen storage in nanocavities; in fact, two studies in that sense has already been reported [1, 2]. All the studies related with the hydrogen storage in porous solids are carried out under cryogenic conditions, usually at 77 K. For some cyanometallates negative thermal expansion behavior has been reported [3], which could be interpreted as evidence of charge redistribution within the T-N-CM- C-N-T chain on the temperature change, particularly under cryogenic conditions. This suggests that in 2D pillared solids low temperature structural transformation could be present, particularly for pillars of certain flexibility and where the electronic structure of layers and pillars remains strongly coupled. Such possibility is explored in this contribution. As prototype of pillared 2D solids T[Ni(CN)4].2pyz, with pyz = Pyrazine were used

π-π Interactions And Magnetic Properties In A Series Of Hybrid Inorganic-organic Crystals

The series of hybrid inorganic-organic solids T(Im) 2[Ni(CN) 4] with T=Fe, Co, Ni and Im=imidazole were prepared by soft chemical routes from aqueous solutions of the involved building units: imidazole, T 2 metal and the [Ni(CN) 4] 2- anionic block. The obtained samples were characterized from infrared and UV-vis spectroscopies, and thermogravimetric, X-ray diffraction and magnetic measurements. Anhydrous solids which crystallize with a monoclinic unit cell, in the I2/a space group with four formula units per cell (Z=4) were obtained. Their crystal structure was solved ab initio from the recorded X-ray powder patterns and then refined by the Rietveld method. The metal T is found with octahedral coordination to four N ends of CN groups and two imidazole molecules while the inner Ni atom preserves its planar coordination. The system of layers remains stacked in an ordered 3D structure through dipole-dipole and π-π interactions between imidazole rings from neighboring layers. In this way, a pillared structure is achieved without requiring the coordination of both nitrogen atoms from imidazole ring. The recorded magnetic data indicate the occurrence of a predominant ferromagnetic interaction at low temperature for Co and Ni but not for Fe. Such magnetic ordering is more favorable for Ni with transition temperature of 14.67 K, which was ascribed to the relatively high polarizing power for this metal. Within the considered T metals, to nickel the highest electron-withdrawing ability corresponds and this leads to an increase for the metal-ligand electron clouds overlapping and to a stronger π-π attractive interaction, two factors that result into a higher magnetic ordering temperature. © 2012 Elsevier Inc. All rights reserved.197317322Linert, W., Verdaguer, M., (2003) Molecular Magnets Recent Highlights, , Springer Wien, New YorkPajerowski, D.M., Andrus, M.J., Gardner, J.E., Knowles, E.S., Meisel, M.W., Talham, D.R., (2010) J. Am. Chem. Soc., 132, p. 4058Day, P., Underhill, A.E., (1999) Metal-Organic and Organic Molecular Magnets, , The Royal Society of Chemistry Cambridge, UKVerdaguer, M., Bleuzen, A., Marvaud, V., Vaissermann, J., Seuleiman, M., Desplanches, C., Scuiller, A., Villain, F., (1999) Coord. Chem. Rev., 1900, p. 1023Martnez-Garcia, R., Knobel, M., Reguera, E., (2006) J. Phys. Chem. B, 110, p. 7296Sarkar, S., Datta, A., Mondal, A., Chopra, D., Ribas, J., Rajak, K.K., Sairam, S.M., Pati, S.K., (2006) J. Phys. Chem. B, 110, p. 12Jose, D., Datta, A., (2011) Cryst. Growth Des., 11, p. 3137Giri, S., Saha, S.K., (2011) J. Phys. Chem. Lett., 2, p. 1567Chi, Y.-H., Yu, L., Shi, J.-M., Zhang, Y.-Q., Hu, T.-Q., Zhang, G.-Q., Shi, W., Cheng, P., (2011) Dalton Trans., 40, p. 1453Li, L.-L., Lin, K.-J., Ho, C.-J., Sun, C.-P., Yang, H.-D., (2006) Chem. Commun., p. 1286Bureekaew, S., Shimomura, S., Kitagawa, S., (2008) Sci. Technol. Adv. Mater., 9, p. 12. , 014108Sakamoto, S., Kitaura, R., Matsuda, R., Kitagawa, S., Kubota, Y., Takata, M., (2010) Chem. Lett., 39, p. 218Rodríguez-Hernández, J., Lemus-Santana, A.A., Ortiz-López, J., Jiménez-Sandoval, S., Reguera, E., (2010) J. Solid State Chem., 183, p. 105Murray, K.S., Kepert, C.J., (2004) Top. Curr. Chem., 233, p. 195Yanai, N., Kaneko, W., Yoneda, K., Ohba, M., Kitagawa, S., (2007) J. Am. Chem. Soc., 129, p. 3496Sheldrick, G.M., (1997) Program for Crystal Structure Determination, Institute fur Anorg, , Chemie Göttingen, GermanyLe Bail, A.L., (2000) ESPOIR: A Program for Solving Structures by Monte Carlo from Powder Diffraction Data, in EPDIC-7, , http://www.cristal.org/sdpd/espoir/S, BarcelonaRodríguez-Carvajal, J., (2005) FullProf 2005 Program, , Institute Louis Brillouin Saclay, FranceLemus-Santana, A.A., Rodríguez-Hernandez, J., Del Castillo, L.F., Basterrechea, M., Reguera, E., (2009) J. Solid State Chem., 182, p. 757Lemus-Santana, A.A., Rodríguez-Hernández, J., González, M., Demeshko, S., Avila, M., Knobel, M., Reguera, E., (2011) J. Solid State Chem., 184, p. 2124Scheiner, S., Yi, M., (1996) J. Phys. Chem., 100, p. 9235Drago, R.S., (1962) Physical Methods for Chemists, , 2nd ed. SaundersCollege Publishing GainesvilleLopes, P.E.M., Lamoureux, G., MacKerell, A.D., (2009) J. Comput. Chem., 30, p. 1821Piacenza, M., Grimme, S., (2005) Chem. Phys. Chem., 6, p. 1554Stone, A.J., (1996) The Theory of Intermolecular Forces (International Series of Monographs on Chemistry), , Oxford University PressHohenstein, E.G., Sherrill, C.D., (2009) J. Phys. Chem. A, 113, p. 878De, S., Drew, M.G.B., Aliaga-Alcalde, N., Datta, D., (2009) Inorg. Chim. Acta, 362, p. 2879Niel, V., Martínez-Agudo, J.M., Muñoz, M.C., Gaspar, A.B., Real, J.-A., (2001) Inorg. Chem., 40, p. 3838Tayagaki, T., Galet, A., Molnár, G., Muñoz, M.C., Tanaka, K., Real, J.-A., Bousseksou, A., (2005) J. Phys. Chem. B, 109, p. 14859Zhang, Y., (1992) Inorg. Chem., 21, p. 388

Unique coordination of pyrazine in T[Ni(CN)4] 2pyz with T ¼ Mn, Zn, Cd

The materials under study, T[Ni(CN)4] 2pyz with T ¼ Mn, Zn, Cd, were prepared by separation of T[Ni(CN)4] layers in citrate aqueous solution to allow the intercalation of the pyrazine molecules. The obtained solids were characterized from chemical analyses, X-ray diffraction, infrared, Raman, thermogravimetry, UV–Vis, magnetic and adsorption data. Their crystal structure was solved from ab initio using direct methods and then refined by the Rietveld method. A unique coordination for pyrazine to metal centers at neighboring layers was observed. The pyrazine molecule is found forming a bridge between Ni and T atoms, quite different from the proposed structures for T ¼ Fe, Ni where it remains coordinated to two T atoms to form a vertical pillar between neighboring layers. The coordination of pyrazine to both Ni and T atoms minimizes the material free volume and leads to form a hydrophobic framework. On heating the solids remain stable up to 140 1C. No CO2 and H2 adsorption was observed in the small free spaces of their frameworks. & 2009 Elsevier Inc. All rights reserved

Synthesis And Characterization Of T[ni(cn)4]·2pyz With T=fe, Ni; Pyz=pyrazine: Formation Of Tpyzni Bridges

The formation of TpyzNi bridges (pyz=pyrazine) in the T[Ni(CN) 4]·2pyz series is known for T=Mn, Zn, Cd and Co but not with T=Fe, Ni. In this contribution the existence of such bridges also for T=Fe, Ni is discussed. The obtained pillared solids, T[Ni(CN)4]·2pyz, were characterized from XRD, TG, UVVis, IR, Raman, Mössbauer and magnetic data. Their crystal structures were refined in the orthorhombic Pmna space group from XRD powder patterns. The structural behavior of these solids on cooling down to 77 K was also studied. In the 180200 K temperature range the occurrence of a structural transition to a monoclinic structure (P21/c space group) was observed. No temperature induced spin transition was observed for Fe[Ni(CN)4]·2pyz. The iron (II) was found to be in high spin electronic state and this configuration is preserved on cooling down to 2 K. The magnetic data indicate the occurrence of a low temperature weak anti-ferromagnetic interaction between T metal centers within the T[Ni(CN) 4] layer. In the paramagnetic region for Ni[Ni(CN) 4]·2pyz, a reversible temperature induced spin transition for the inner Ni atom was detected. © 2011 Elsevier Inc. All rights reserved.184821242130Li, Y., Liu, Y., Wang, Y., Leng, Y., Xie, L., Li, X., (2007) Int. J. Hydrog. Energy, 32, p. 3411Culp, J.T., Natesakhawat, S., Smith, M.R., Bittner, E., Matranga, C., Bockrath, B., (2008) J. Phys. Chem. C, 112, p. 7079Culp, J.T., Smith, M.R., Bittner, E., Bockrath, B., (2008) J. Am. Chem. Soc., 130, p. 12427Niel, V., Martínez-Agudo, J.M., Muñoz, M.C., Gaspar, A.B., Real, J.-A., (2001) Inorg. Chem., 40, p. 3838Molnár, G., Niel, V., Gaspar, A.B., Real, J.-A., Zwick, A., Bousseksou, A., McGarvey, J.J., (2002) J. Phys. Chem. B, 106, p. 9701Molnár, G., Niel, V., Real, J.-A., Dubrovisnky, L., Bousseksou, A., McGarvey, J.J., (2003) J. Phys. Chem. B, 107, p. 3149Molnár, G., Kitazawa, T., Dubrovisnky, L., McGarvey, J.J., Bousseksou, A., (2004) J. Phys.: Condens. Matter, 16, p. 1129Tayagaki, T., Galet, A., Molnár, G., Muñoz, M.C., Tanaka, K., Real, J.-A., Bousseksou, A., (2005) J. Phys. Chem. B, 109, p. 14859Cobo, S., Ostrovskii, D., Bonhommeau, S., Vandier, L., Molnár, G., Salmon, L., Tanaka, K., Bousseksou, A., (2008) J. Am. Chem. Soc., 130, p. 9019Agustí, G., Cobo, S., Gaspar, A.B., Molnár, G., Moussa, N.O., Szilágyi, P.A., Pálfi, V., Bousseksou, A., (2008) Chem. Mater., 20, p. 6721Southom, P.D., Liu, L., Fellows, E.A., Price, D.J., Halder, G.J., Chapman, K.W., Moubaraki, B., Kepert, C.J., (2009) J. Am. Chem. Soc., 131, p. 10998Lemus-Santana, A.A., Rodríguez-Hernández, J., Del Castillo, L.F., Basterrechea, M., Reguera, E., (2009) J. Solid State Chem., 182, p. 757Rodríguez-Hernández, J., Lemus-Santana, A.A., Ortiz-López, J., Jiménez-Sandoval, S., Reguera, E., (2010) J. Solid State Chem., 183, p. 105Ferreira, F.F., Granado, E., Carvalho, Jr.W., Kycia, S.W., Bruno, D., Droppa, Jr.R., (2006) J. Synchrotron Radiat., 13, p. 46Rodríguez-Carvajal, J., (2005) FullProf 2005 Program, , Institute Louis Brillouin Saclay, FranceDrago, R.S., (1962) Physical Methods for Chemists, , 2nd ed. Saunders College Publishing Gainesville Chapter 11Greenwood, N.N., Earnshaw, A., (1998) Chemistry of the Elements, , 2nd ed. Butterworth-Heinemann Great BritainNakamoto, K., (1995) Infrared and Raman Spectra of Inorganic and Coordination Compounds, , John-Wiley & Sons New York, Chichester, Brisbane, Toronto, SingaporeMartínez-Garcia, R., Knobel, M., Reguera, E., (2006) J. Phys. Chem. B, 110, p. 729