Poly(N-vinyl-2-pyrrolidone) stabilized nickel(0) nanoparticles as catalyst for hydrogen generation from the methanolysis of ammonia borane

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Kimya Bölümü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: NİHAN ZÜLAY KILIÇASLAN

Danışman: SAİM ÖZKAR

Özet:

This dissertion includes the preparation and characterization of poly(N-vinyl-2-pyrrolidone) stabilized nickel(0) nanoparticles, and investigation of their catalytic activity in hydrogen generation from catalytic methanolysis of ammonia-borane (AB). PVP-stabilized nickel(0) nanoparticles were prepared from the reduction of nickel(II) ethylhexanoate in the presence of PVP as stabilizer, by hydrazine borane at room temperature. PVP-stabilized nickel(0) nanoparticles were isolated from reaction medium by centrifugation and characterized using UV-vis spectroscopy, TEM and XPS techniques. PVP-stabilized nickel(0) nanoparticles have an average particle size of 3.0 ± 0.7 nm. PVP-stabilized nickel(0) nanoparticles were found as highly active and stable catalyst with 5300 turnovers over 52 hours in hydrogen generation from the methanolysis of ammonia borane at room temperature. Carbon disulfide poisoning test was performed to show that PVP-stabilized nickel(0) nanoparticles are true heterogeneous catalyst for the methanolysis of AB. This report also includes the kinetic studies of methanolysis of AB catalyzed by PVP-stabilized nickel(0) nanoparticles for understanding the effects of substrate concentration, catalyst concentration, and temperature. Activation parameters (Ea, ΔH and ΔS) of catalytic methanolysis reaction of AB were calculated from the evaluation of kinetic data.