Theoretical investigation of mixed metal organic frameworks as H2 adsorbents
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Tarih
2022
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Moleküler hidrojen (H2) çevre dostu, yenilenebilir ve sürdürülebilir bir enerji taşıyıcısıdır. Enerji gerektiren uygulamalarda moleküler hidrojenin (H2) sınırlı kullanımının en büyük nedenlerinden biri, güvenli ve yüksek performanslı hidrojen depolama sistemlerinin tam olarak geliştirilememesidir. Yeni nesil nano gözenekli malzemeler, prensip olarak, H2 depolama sorununun çözümü olabilecek H2'yi depolayabilir. Yeni nesil nano gözenekli malzemeler olan Metal Organik Kafesler (MOF), H2 depolama uygulamaları için umut verici adaylar olarak gösterilmektedir. Yapılarında en az iki farklı metal iyonu içeren MOF'lar, çoklu metal MOF'lar (MM-MOF) olarak adlandırılır ve tek metal içeren yapılara göre H2'yi daha yüksek miktarlarda adsorbe edebilirler. Bu tezde, farklı topolojik ve kimyasal özelliklere sahip 27 MM-MOF'un H2 adsorpsiyon kapasiteleri, Grand Kanonik Monte Carlo (GCMC) ve Yoğunluk Fonksiyoneli Teorisi (DFT) simülasyonları kullanılarak teorik olarak araştırılmıştır. İncelenen malzemeler iki gruba ayrılmıştır. 1. grup malzemeler daha önce deneysel olarak sentezlenirken, 2. grup malzemeler You ve ark. (2020) tarafından tasarlanan varsayımsal MM-MOF'lardır. Bildiğimiz kadarıyla, seçilen MM-MOF'ların H2 depolama performansları daha önce literatürde çalışılmamıştır. MM-MOF'ların H2 adsorpsiyon izotermleri, 233 K'da ve 1 ile 100 bar arasındaki basınçlarda gerçekleştirilen GCMC simülasyonları ile tahmin edilmiştir. H2'yi modellemek için 5 bölgeli (anizotropik) atomik modelleme kullanılmıştır. Elektrostatik etkileşimlerin hesaplanması için gerekli olan MM-MOF atomlarının atomik yükleri DDEC yöntemi uygulanarak belirlenmiştir. MM-MOF'ların H2 depolama kapasitesi ile topolojik ve kimyasal özellikleri arasında korelasyon kurulmuş ve H2'yi hem hacimsel hem de gravimetrik olarak yüksek miktarda adsorplayarak en iyi performans gösteren altı adet MM-MOF belirlenmiştir. DFT simülasyonları uygulanarak H2'ni en iyi adsorbe edebilen malzemeler için elektronik yapı analizi yapılmıştır. Anahtar Kelimeler: Grand Kanonik Monte Carlo Simülasyonları, Yoğunluk Fonksiyoneli Teorisi
Molecular hydrogen (H2) is an environmentally friendly, renewable, and sustainable energy carrier. One of the biggest reasons for the limited use of molecular hydrogen (H2) in energy required applications is the inability to fully develop safe and high-performance hydrogen storage systems. New generation nanoporous materials, in principle, can store H2 which could be solution of the H2 storage challenge. Metal Organic Frameworks (MOF), which are new generation nanoporous materials are shown to be promising candidates for the H2 storage applications. MOFs that contain at least two different metal ions in their structures are called as mixed-metal MOFs (MM-MOF) and they could adsorb H2 in higher amounts compared to structures containing single metal nodes. In this thesis, the H2 adsorption capacities of the 27 MM-MOFs having different topological and chemical features have been theoretically investigated using Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) simulations. Materials under consideration are divided into two groups. While the 1st group materials have been experimentally synthesized before, the 2nd group materials are hypothetical MM-MOFs designed by You et al. (2020). To the best of our knowledge, H2 storage performances of the selected MM-MOFs have not been studied in the literature before. H2 adsorption isotherms of the MM-MOFs have been predicted by GCMC simulations carried out at 233 K and at pressures between 1 and 100 bar. 5-site (anisotropic) atomic modeling has been used for modeling H2. The atomic point charges of the MM-MOF atoms required for calculating electrostatic interactions have been determined by applying the DDEC method. Correlation between H2 storage capacity of the MM-MOFs and their topological and chemical features have been established and six materials are determined to be the best performing MM-MOFs that can adsorb H2 both volumetrically and gravimetrically. Electronic structure analysis has been carried out for the top H2 adsorbing materials by applying DFT simulations. Keywords: Grand Canonical Monte Carlo Simulations, Density Functional Theory
Molecular hydrogen (H2) is an environmentally friendly, renewable, and sustainable energy carrier. One of the biggest reasons for the limited use of molecular hydrogen (H2) in energy required applications is the inability to fully develop safe and high-performance hydrogen storage systems. New generation nanoporous materials, in principle, can store H2 which could be solution of the H2 storage challenge. Metal Organic Frameworks (MOF), which are new generation nanoporous materials are shown to be promising candidates for the H2 storage applications. MOFs that contain at least two different metal ions in their structures are called as mixed-metal MOFs (MM-MOF) and they could adsorb H2 in higher amounts compared to structures containing single metal nodes. In this thesis, the H2 adsorption capacities of the 27 MM-MOFs having different topological and chemical features have been theoretically investigated using Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) simulations. Materials under consideration are divided into two groups. While the 1st group materials have been experimentally synthesized before, the 2nd group materials are hypothetical MM-MOFs designed by You et al. (2020). To the best of our knowledge, H2 storage performances of the selected MM-MOFs have not been studied in the literature before. H2 adsorption isotherms of the MM-MOFs have been predicted by GCMC simulations carried out at 233 K and at pressures between 1 and 100 bar. 5-site (anisotropic) atomic modeling has been used for modeling H2. The atomic point charges of the MM-MOF atoms required for calculating electrostatic interactions have been determined by applying the DDEC method. Correlation between H2 storage capacity of the MM-MOFs and their topological and chemical features have been established and six materials are determined to be the best performing MM-MOFs that can adsorb H2 both volumetrically and gravimetrically. Electronic structure analysis has been carried out for the top H2 adsorbing materials by applying DFT simulations. Keywords: Grand Canonical Monte Carlo Simulations, Density Functional Theory
Açıklama
Lisansüstü Eğitim Enstitüsü, Biyomühendislik Ana Bilim Dalı, Biyomühendislik Bilim Dalı
Anahtar Kelimeler
Kimya, Chemistry ; Kimya Mühendisliği
