碳纳米管负载CuO-CeO_2催化剂用于CO选择性氧化

分别以碳纳米管(CNTs)和68%浓HNO3处理的CNTs为载体,采用超声辅助的浸渍法制备负载型Cu O-CeO_2复合氧化物催化剂,用于富氢气中CO选择氧化。采用XPS和LRS对预处理前后CNTs管的结构与表面性质进行研究。采用XRD和H2-TPR对催化剂结构进行表征。结果表明,经浓HNO3处理的CNTs载体表面含氧官能团—COOH相对含量提高了约68%,且表面缺陷增多,有助于催化剂活性组分的沉积和分散。以此负载的Cu O-CeO_2催化剂上Cu O物种具有较好的分散性,晶粒尺寸较小,催化剂表现出强的低温氧化还原能力,且表面CO氧化活性位增多,对CO选择性氧化具有低温高活性,T50低至90℃,反应温度低于140℃保持高选择性,且CO完全转化反应温度窗口拓宽宽至30℃。

Carbon nanotubes supported CuO-CeO2 catalysts for selective oxidation of CO

Using carbon nanotubes(CNTs) and 68% HNO₃ treated CNTs as the carriers,respectively,CuO-CeO₂ supported catalysts for selective oxidation of CO in rich hydrogen atmosphere were prepared by ultrasonic assisted impregnation method.The structure and surface properties of carbon nanotubes before and after pre-treatment were investigated by means of X-ray photoelectron spectroscopy and Laser Raman spectroscopy.The structures of the catalysts were characterized with X-ray diffraction and temperature-programmed reduction.The results showed that on the surface of carbon nanotubes treated by concentrated HNO₃,the relative content of functional groups —COOH was improvedby about 68% and the surface defects increased,which contributed to the deposition and dispersion of the active components of the catalyst.CuO-CeO₂ catalyst with HNO₃ treated carbon nanotubes as the support possessed high dispersion of CuO species and small crystallite sizes and exhibited strong low-temperature redox capacity,and its surface activity sites for CO oxidation at low-temperature increased.The catalyst exhibited high low-temperature activity for CO selective oxidation.The T₅₀ reduced to 90 ℃.High selectivity was maintained when reaction temperature was below 140 ℃ and the temperature window of total CO conversion was broadened to 30 ℃.