Loading Of Nano Metal Cu For Catalytic Hydrogen Production From An Aqueous Formaldehyde Solution: Effect Of Supporter

As one of clean energy sources,hydrogen energy possess more distinct advantages than traditional fossil energy.It is key to obtain hydrogen fuel for hydrogen energy applications.Formaldehyde can produce hydrogen in alkaline solution.This reaction has two major benefits: 1)the resulting gas was pure hydrogen,excluding CO or CO₂;2)the reaction conditions were very mild.Nano-metals can catalyze hydrogen production from formaldehyde.However,the nano-metals can easily agglomerate,decreasing the catalytic activity and stability.In this dissertation,nano-Cu was loaded on three supporters to improve activity and stability.The main contents are divided into following three parts:Nano metal Cu was loaded on Y₂O₃ by NaBH₄ reduction method.The sample was characterized by X-ray diffraction?XRD?,X-rayphotoelectron spectroscopy?XPS?,transmission electron microscopy?TEM?and adsorption measurment of OHon Y₂O₃.The results show that there is a thin layer of Y?OH?₃ on the surface of Y₂O₃,which can preferentially adsorb OH-,that is,“enrichment” of OH-on Y₂O₃;metal Cu was loaded on Y₂O₃ in the form of nano particles.The performance of Cu supported on Y₂O₃?Cu/Y₂O₃?catalyst was investigated in alkaline formaldehyde solution.The results show that under low alkalinity,Cu/Y₂O₃ exhibits higher activity for hydrogen production than unloaded nano metal Cu.When the concentration of sodium hydroxide is 0.050 mol.L-1,the produced hydrogen amount of Cu/Y₂O₃ is 7.8 times as high as that of nano-Cu,which can be attributed to “enrichment” effect of OH-on Y₂O₃,leading to production of the higher concentration of active CH2?OH?O-?formaldehyde anion?species on Y₂O₃.The stability of Cu/Y₂O₃ is improved compared with that of unloaded nano-Cu.The reason is that the load of Cu on Y₂O₃ prevents growth of Cu particles during the reaction.?2?Cu /BiOCl catalyst was prepared by impregnation reduction method,and the performance of catalytic hydrogen production from formaldehyde was studied.Under the same conditions,Cu/BiOCl composite catalyst exhibits better catalytic hydrogen production than the nano-Cu when the loading is 5 wt%.In the stability test,nano-copper after 1.5 h reaction losses the activity of hydrogen production,whereas Cu/BiOCl catalyst can maintain its high activity.By further optimizing the reaction conditions,such as formaldehyde,sodium hydroxide concentration,metal loading,etc.,the hydrogen production amount for 5 wt% Cu/BiOCl after 80 min reaction can reach 140 ?mol in the nitrogen atmosphere.?3?Nano-Cu decorated on TiO₂ nanoparticles exhibit the highly efficient catalytic activity and good stability for hydrogen generation from formaldehyde solution,which is much higher than those of pure Cu nanoparticles.By further optimizing the reaction parameters,the hydrogen generation amount for 10 wt%Cu on TiO₂ after 80 min reaction can reach 120 ?mol in the nitrogen atmosphere.