Preparation Of Pd Catalytic Materials By Atmospheric-Pressure Ethanol Cold Plasma And Their Applications

Supported Pd catalytic materials have been widely investigated and applied in petrochemical industry,organic synthesis and industrial catalysis,etc.The traditional preparation methods generally need high energy cost and complex processes.Atmospheric–pressure?AP?cold plasma is a simple,fast and effective new method for preparing supported metal catalytic materials.However,hydrogen-containing working gases?such as H₂ and NH₃?are usually required as the reducing agent in the preparation process.Ethanol,a renewable hydrogen rich resource,which is easy to obtain,store and transport.Recently,hydrogen production by reforming of ethanol has become a research hotspot.In this work,supported Pd catalytic materials were synthesized by AP cold plasma technology with alcohol as hydrogen source.The structure and properties of the catalytic materials were investigated,and the preparation mechanism of AP alcohol cold plasma were discussed.Firstly,the feasibility of AP alcohol?methanol and ethanol?cold plasma for reducing P25?commercial TiO₂?supported metal?Au,Pd,Ag,Pt?ions was investigated.The results of X-ray photoelectron spectroscopy?XPS?,transmission electron microscopy?TEM?and ultraviolet–visible diffuse reflection spectroscopy?UV-Vis DRS?show that the metal ions were successfully reduced by AP alcohol cold plasma.Compared to AP hydrogen and methanol cold plasma,the supported gold catalytic materials prepared by AP ethanol cold plasma has higher metallic composition,smaller size of gold nanoparticles,and higher absorption peak.Secondly,Pd/P25-EP-C catalytic materials was prepared by AP ethanol cold plasma.Compared to Pd/P25-HP prepared by AP hydrogen cold plasma,Pd/P25-EP-C exhibits higher catalytic activity for CO oxidation,and the Pd nanoparticles have smaller size?about 1.6 nm?and better dispersion.The turnover frequencies values for Pd/P25-EP-C at 110 ? and 120 ?,are 3.6 and 3.1 times as that for Pd/P25-HP.Thirdly,Pd/C catalytic materials were prepared by AP ethanol cold plasma using activated carbon as the support,and the effects of the preparation parameters on the structure and performance of the catalytic materials was explored.The optimal preparation conditions are:36 kV discharge voltage,10 min discharge time and 550 ? calcination temperature.The 100%CO conversion temperature(T₁₀₀)of Pd/C-EP-Ar550 is 140 ?,which is similar with that of Pd/C-HP-Ar550 prepared by AP hydrogen cold plasma.Not only active hydrogen species but also excited-states CO molecules can be formed during AP ethanol cold plasma,both of which can reduce metal ions.In addition,carbon protective layer can also be formed by alcohol dissociation,which can effectively protect the Pd nanoparticles,facilitate the interaction between the metal and support.Consequently,a stable catalytic performance can be obtained.AP ethanol cold plasma is safe and environmentally friendly since it avoids using explosive hydrogen gas as hydrogen source in the preparation process.It is a safe and effective new method for preparing supported metal catalytic materials,which has important theoretical research significance and practical application prospect in the field of supported metal catalytic materials preparation.