Intermolecular potential energy functions for CO2 have been developed from first principles for use in heterogeneous systems, including one with explicit polarization. The intermolecular potentials have been expressed in a transferable form and parameterized from nearly exact electronic structure calculations. Models with and without explicit many-body polarization effects, known to be important in simulation of interfacial processes, are constructed. The models have been validated on pressure-density isotherms of bulk CO2 and adsorption in three metal-organic framework (MOF) materials. The present models appear to offer advantages over high quality fluid/liquid state potentials in describing CO2 interactions in interfacial environments where sorbates adopt orientations not commonly explored in bulk fluids. Thus, the nonpolar CO2-PHAST and polarizable CO2-PHAST* potentials are recommended for materials/interfacial simulations.

Metal-organic frameworks (MOFs), a new class of porous solids comprised of metal-containing nodes linked by organic ligands, have become promising materials for gas separations. In particular, their flexible chemistry makes them attractive for CO2 capture from flue gas streams in post-combustion plants. Although numerous efforts have been exerted on the investigation of MOFs for CO2 capture, the exploration of the effects from coexisting components present in very dilute proportions in flue gases is limited because of the experimental difficulty to determine the coadsorption of CO2 with trace components. In this regard, molecular simulations show superiority. In this study, molecular simulations are used to estimate the influence of impurities: water, O2, and SO2 on post-combustion CO2 capture in MOFs. Firstly, two MOFs with coordinatively unsaturated metal sites (CUMs), HKUST-1 and Mg-MOF-74 are explored. Increase of CO2 adsorption is observed for hydrated HKUST-1; on the contrary, the opposite water adsorption behavior is observed in hydrated Mg-MOF-74, leading to decrease of CO2 adsorption. Further, water effects on CO2 capture in M-HKUST1 (M = Mg, Zn, Co, Ni) are evaluated to test whether comparing the binding energy could be a general method to evaluate water effects in MOFs with CUMs. It is found that the method works well for Zn-, Co-, and Ni-HKUST1 but partially for Mg-HKUST1. In addition, the effects of O2 and SO2 on CO2 capture in MOFs are also investigated for the first time, showing that the effects of O2 may be negligible but SO2 has negative effects in the CO2 capture process in HKUST-1 systems. Secondly, the influences of water on CO2 capture in three UiO-66 MOFs with functional groups, –NH2, –OH and –Br are explored, respectively. For UiO-66-NH2 and -OH, the presence of water lowers CO2 adsorption significantly; in contrast, water shows much smaller effects in UiO-66-Br. Moreover, the presence of SO2 decreases water adsorption but enhances CO2 uptakes slightly in both UiO-66-NH2 and -Br. Finally, the effects of impurities on CO2 capture in a MOF with suitable pore size (PCN-200) are analyzed. The adsorption of both CO2 and N2 decrease substantially even with 1% water present in the mixture. In addition, the presence of low SO2 does not show obvious effect in PCN-200. However, a lower CO2 adsorption is observed for a mixture with a high SO2 content. In collaboration with experimental groups, the performances of three new MOFs in CO2 capture are evaluated using molecular simulations. The computational results demonstrate the feasibility of precisely designing single-molecule traps (SMT) for CO2 capture. Also, a multi-functional MOF with micro-porosity, open Cu2+ sites and amine groups has also proved computationally the selective adsorption of CO2 over CH4 and N2. Last, we demonstrate that charge separation is an effective strategy for improving CO2 capture in MOFs.

Thesis (M.S.)--Ohio University, November, 2001. / Title from PDF t.p.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 156-165). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 129-137). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--Ohio University, March, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 147-151)

The present thesis proposes to explore the potential of Zeolitic Imidazolate Framework ZIFs for CO2 capture applications in the conditions required by the Pressure Swing Adsorption separations process. Molecular modelling methods, combining Monte Carlo, Density Functional Theory and ab-initio simulations, were employed to mimic pure and mixture gas adsorption in ZIF materials. A transferable Force Field specifically developed for ZIFs materials is used to characterize a large variety of frameworks. Theses studies enable us to better understand the phenomena acting during adsorption process. Thereby several innovative modifications are proposed to enhance the ZIFs properties for CO2 capture and a series of hypothetical ZIFs are designed, characterized and compared to existing materials. The results cumulated during this thesis were then summarized to propose a first correlative model able to predict ZIF properties from a set of solids descriptors. This study enables to guide the structure design to optimize the ZIF properties.

abstract: Metal Organic Frameworks(MOFs) have been used in various applications, including sensors. The unique crystalline structure of MOFs in addition to controllability of their pore size and their intake selectivity makes them a promising method of detection. Detection of metal ions in water using a binary mixture of luminescent MOFs has been reported. 3 MOFs(ZrPDA, UiO-66 and UiO-66-NH2) as detectors and 4 metal ions(Pb2+, Ni2+, Ba2+ and Cu2+) as the target species were chosen based on cost, water stability, application and end goals. It is possible to detect metal ions such as Pb2+ at concentrations at low as 0.005 molar using MOFs. Also, based on the luminescence responses, a method of distinguishing between similar metal ions has been proposed. It is shown that using a mixture of MOFs with dierent reaction to metal ions can lead to unique and specic 3D luminescence maps, which can be used to identify the present metal ions in water and their amount. In addition to the response of a single MOF to addition of a single metal ion, luminescence response of ZrPDA + UiO-66 mixture to increasing concentration of each of 4 metal ions was studied, and summarized. A new peak is observed in the mixture, that did not exist before, and it is proposed that this peak requires metal ions to activate / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2018

The research in the area of metal-organic frameworks (MOFs) continues to be interesting for their unique structures and tunable properties. In this thesis, the various aspects of metal-organic frameworks (MOFs) compounds are presented. As part of this study, preparation of MOFs of transition metals (Mn, Co, Ni, Zn), rare-earth metals (Y, La, Pr, Nd, Gd, Dy) and mixed metals (3d-4f) using aromatic carboxylates as linker ligands were accomplished. Structures of the synthesized compounds have been determined by single crystal X-ray diffraction technique. Magnetic properties of the transition metal based compounds have been studied by SQUID magnetometer and the magnetic behaviors have been correlated with their structures using suitable theoretical model. Photocatalytic properties on transition metal and mixed metal compounds have been investigated. Ligand-sensitized metal-center emission has been studied on the Eu3+ and Tb3+ doped MOF compounds of La and Y. Up-conversion luminescence properties of Nd based compounds have also been studied. To gain an insight into the possible mechanism of the formation of MOF compounds, a detailed study of the role of temperature and time during the synthesis has been undertaken. In addition, the transformations of low-dimensional structures to structures of higher dimensionality was also studied, both in the solid state as well as in the solution mediated processes. In Chapter 1 of the thesis an overview of framework compounds is presented. In Chapter 2, the synthesis, structure and magnetic properties of benzene tricaboxylate and 4,4’-oxybis(benzoate) compounds of 3d metals are presented. Some of these compounds show unusual structure and interesting magnetic properties. For example, three-dimensional MOF with -Mn-O-Mn- Kagome layer exhibits canted antiferromagntic behavior. Three-dimensional MOF based on body centered arrangement of Co4 clusters shows two-dimensional ferromagnetic behavior. In Chapter 3, the role of temperature and time of reaction in the formation of MOF compounds and the transformation studies are presented. These studies give a clue regarding the mechanism for the synthesis of MOF compound. In chapter 4, synthesis, structure and luminescent properties of rare-earth and 3d-4f mixed metal compounds are presented. The thermal decomposition of Gd-Co-pyridine carboxylate indicates the formation of nano-sized perovskite oxide at temperature ~ 700 °C. In chapter 5, the photocatalytic behavior for the decomposition of organic dyes using MOF compounds are presented.

Submitted by Etelvina Domingos (etelvina.domingos@ufpe.br) on 2015-03-11T17:35:11Z No. of bitstreams: 2 Etelino_Dissertação final 09102012.pdf: 9253307 bytes, checksum: 22d8f2b2d1f4d51f54320eb4f05a8303 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-11T17:35:11Z (GMT). No. of bitstreams: 2 Etelino_Dissertação final 09102012.pdf: 9253307 bytes, checksum: 22d8f2b2d1f4d51f54320eb4f05a8303 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-09 / CNPq CAPES / No presente trabalho discutimos a preparação e a caracterização de nanofibras poliméricas obtidas pelo método da eletrofiação (“electrospinning”) com o objetivo de desenvolver novos materiais com morfologias fibrosas. Para isso, foram utilizados três diferentes tipos de compósitos. O primeiro foi um compósito de nanopartículas de ZnO com polipirrol (PPi) e álcool polivinílico (PVA). O segundo compósito foi constituído por PVA e dois diferentes polímeros de coordenação, [(Ln)(DPA)(HDPA)] (onde Ln = Tb3+ ou Eu3+), também conhecidos como MOF – de (“Metal Organic Framework”). Finalmente, o terceiro foi um compósito de N-(4-nitro-2-fenoxifenil)metanesulfonamida (nimesulida) com PVA. As nanofibras obtidas foram caracterizadas por espectroscopia na região do infravermelho e do UV-Vis, espectroscopia de fluorescência, medidas elétricas de corrente e voltagem, microscopia eletrônica de varredura (MEV), microscopia de fluorescência e análise termogravimétrica (TGA). Muito embora todas as nanofibras estudadas apresentassem as mesmas características morfológicas, elas exibiram diferentes propriedades físicas e químicas. As nanofibras de PVA/ZnO/PPi apresentaram fluorescência na região visível com comprimento de onda de 526 nm e, quando expostas à luz ultravioleta, sua resistência elétrica sofre um aumento de cerca de duas ordens de grandeza (um fato atribuído a um provável aumento da zona de depleção da junção ZnO/PPi quando o material é exposto a luz). Já as nanofibras com MOFs exibiram altas intensidades de fluorescência que, de acordo com a natureza do metal presente (se Tb ou Eu), pode apresentar emissão na região visível: verde ou vermelho, respectivamente. Por fim, a caracterização espectroscópica das nanofibras com nimesulida mostraram que o fármaco se encontra incorporado na matriz polimérica, pois é possível observar sua banda de absorção característica no UV-Vis em 315 nm, como também o espectro de infravermelho das nanofibras revela a presença das bandas típicas de absorção tanto da nimesulida quanto do PVA.