氮化碳负载铂催化剂的制备、表征及对肉桂醛加氢的催化性能

通过尿素的高温聚合制备了片层状氮化碳g-C3N4,采用乙二醇还原法载铂得到Pt/g-C3N4催化剂。以X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、比表面与孔隙度分析和电感耦合等离子体原子发射光谱(ICP-AES)等对所制备催化剂进行了表征,并在肉桂醛加氢反应中考察了其催化性能。结果表明,载体g-C3N4含有大量的含N基团,能有效稳定金属纳米粒子;Pt纳米粒子均匀分散在g-C3N4表面,且Pt粒径在2~3 nm之间;载体煅烧温度对催化剂的择性加氢性能有明显影响,550℃煅烧后的g-C3N4,所负载Pt在较温和的条件下表现出较明显的活性,肉桂醛转化率为30%,肉桂醇选择性为66%左右。重复使用3次,催化剂活性基本不变,具有良好的稳定性。

Preparation and mechanical properties of two nickel base alloy coatings achieved by electrospark deposition

Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique （ESD）. Forming properties, thickness, microhardness and wear resistance of the coatings were investigated. The chemical composition and cross- section morphology were analyzed through energy dispersive spectrum （EDS） and metalloscope. The results show that the technological parameter window of Ni398 is larger than that of Ni818 electrode. However, other properties of the Ni818 coating, such as thickness and microhardness, were better than those of the Ni398 coating. Especially the wornout volume of Ni818 coating is only 1/6 of that for 1045 steel and 1/3 for Ni398 coating. Chemical composition analysis indicated that the addition of Mo promoted grain refinement of nickel alloy. Metallographic analysis shows that the molten droplets of Ni398 coatings have an average structure thickness of 20-40 #m while the microstructure of Ni818 coatings is flat with width of 5-20 #m.