Enthalpy of formation and dehydration of lithium and sodium zeolite beta |
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| Affiliation: | 1. Department of Chemistry, Dongguk University-Seoul, 30, Pil-Dong-ro 1-gil, Jung-gu, Seoul 04620, Republic of Korea;2. ARC Centre of Excellence for Electromaterials Science, IPRI, AIIM Facility, Innovation Campus, University of Wollongong, NSW 2522, Australia;3. Radioisotope Research Division, Korea Atomic Energy Research Institute, 111, Daedeok-daero 989 beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea;4. Advance Radiation Technology Institute, Korea Atomic Energy Research Institute, 29, Geumgu-gil, Jeongeup-si, Jeollabuk-do 56212, Republic of Korea;1. Department of Mechanical Engineering, Indian Institute of Technology, Guwahati 781039, Assam, India;2. Department of Chemistry, Indian Institute of Technology, Guwahati 781039, Assam, India;3. Department of Chemical Engineering, Indian Institute of Technology, Guwahati 781039, Assam, India;1. State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, No. 2 Ling-gong Road, Dalian, China;2. Dalian Ligong Qiwangda Chemical Technology Co., Ltd., Songmudao Chemical Zone, Puwan New Area, Dalian, China;1. Department of Chemical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK;2. Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal |
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| Abstract: | Zeolite Li-BEA and Na-BEA with Si/Al = 3–4 were synthesized by alumination and ion exchange, then characterized by XRD, TG–DSC and NMR. The enthalpies of formation and dehydration of Li and Na ion exchanged zeolite beta are investigated by high temperature oxide melt solution calorimetry. For Li-BEA, the formation enthalpies of formation from oxides at 25 °C are 25.6 ± 1.7 kJ/mol TO2 for the dehydrated zeolite and −8.45 ± 0.94 kJ/mol TO2 for the fully hydrated zeolite; for Na-BEA they are −2.4 ± 0.6 kJ/mol TO2 for the dehydrated and −17.8 ± 1.0 kJ/mol TO2 for the fully hydrated zeolite. The integral dehydration enthalpy at 25 °C is 33.2 ± 1.8 kJ/mol H2O for Li-BEA and 16.5 ± 1.1 kJ/mol H2O for Na-BEA. The partial molar dehydration enthalpies of both Li-BEA and Na-BEA are a linear function of water content. Molecular mechanics simulations explore the cation and water molecule positions in the framework at several water contents. |
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