Synthesis And Catalytic Performance Of Ru-based Nanocomposite In Hydrolytic Dehydrogenation Of Ammonia Borane

Ammonia borane?NH₃BH₃,denoted as AB?has been identified as an attractive candidate,because of high hydrogen content?19.6wt%?,stability under ordinary storage conditions,and environmental benignancy.So far,noble?Ru?and transition metal?Cu,Co,Ni?NPs were tested for hydrolytic dehydrogenation of AB.The experiments show that noble metal NPs have been identified to be effective for catalytic hydrolysis of AB,more non-noble metal component in the catalyst not only improves the catalytic activity,but also reduces the cost which is the key to building a sustainable development of industry in the future.CNTs and TNTs have extensive application prospect in the field of catalyst carrier,due to their high specific surface area,large length to diameter ratio,high performance of chemical inertness and good conductivity.The following three aspects were mainly included:?1?Trimetallic RuCuNi nanoparticles?NPs?were successfully immobilized on carbon nano-tubes?CNTs?,and the RuCuNi/CNTs catalyst was applied to the hydrolytic dehydrogenation of ammonia borane?AB?.In order to compare catalytic activity of monometallic,bimetallic and trimetallic supported on CNTs,monometallic?Ru,Cu,Ni?,bimetallic?RuCu,RuNi?and trimetallic?RuCuNi?supported on CNTs with the same content as well as pure RuCuNi NPs have been synthesized.XRD?TEM?ICP-AES?XPS techniques have been employed to analyze the catalyst's crystal structure,morphology,metal content and valence state.It shows that the RuCuNi/CNTs exhibits the highest catalytic activity and stability than its monometallic and bimetallic supported on CNTs catalyst which contributes to the strong trimetallic synergistic effects,uniform dispersion of nanoparticles on the surface of carbon nanotubes as well as bi-functional effects between RuCuNi nanoparticles and the host of CNTs.In addition,The RuCuNi/CNTs catalyst's activation energy?Ea?and the turn over frequency?TOF?are 36.67 kl/mol and 311.15 mol H₂ min^-1?mol Ru?^-1,respectively.And 61.9%of the initial activity is retained after five cycles.?2?Different proportion of metal Ru@CoNi/CNTs have been successfully in situ synthesized via a one-step reduction method,and applied to hydrolytic dehydrogenation of ammonia borane.Research demonstrates that the best metal proportion of catalyst(Rui@Co_2.4Ni_3.6/CNTs)exhibits the highest catalytic activity and stability.Ru@CoNi core-shell NPs supported on CNTs exhibit much higher catalytic activity for hydrolytic dehydrogenation of AB than RuCoNi alloy supported on CNTs and Ru@CoNi core-shell NPs because of metallic synergistic effects,core-shell structure of metal nanoparticles as well as bi-functional effects between RuCoNi nanoparticles and the host of CNTs.The Ru@CoNi/CNTs catalyst's Ea and TOF are 23.53 kl/mol and 408.9 mol H₂ min^-1?mol Ru?^-1,respectively.In addition,60%of the initial activity is retained after five cycles.?3?Different molar ratio of Ru,Ni supported on TNTs have been synthesized using a liquid impregnation-reduction method,applied to the hydrolytic dehydrogenation of ammonia borane.XRD?TEM?ICP-AES techniques have been employed to analyze the catalyst's crystal structure,morphology,size and metal content.different proportion of metal content on the catalyst have a great influence towards the catalytic activity,Ru₁Ni₅/TNTs has the best performance thanks to RuNi bimetallic synergistic effects and bi-functional effects between metal and the host of TNTs.The activation energy?Ea?and the turn over frequency?TOF?of this RuiNis/TNTs catalyst are 35.18 kl/mol and 365.6mol H₂ min^-1?mol Ru?^-1,respectively.In addition,the Ru₁Ni₅/TNTs catalyst show satisfied durable stability after five cycles and 66.7%of the initial activity is retained.