欢迎访问《环境科学学报》编辑部网站！

快速检索			高级检索

研究报告

Shape effect of ceria nanocrystals with various morphologies on toluene catalytic oxidation

基金项目：国家自然科学基金项目(No.51108187, 50978103);中央高校基本科研业务费专项资金(No.2012ZM0041, 2011ZM0048)

叶代启
1. 华南理工大学环境与能源学院, 广州 510006;
2. 大气环境与污染控制广东省重点实验室, 广州 510006;
3. 广东高校大气污染控制工程研究中心, 广州 510006

摘要：采用水热法合成CeO₂纳米棒、纳米颗粒和纳米立方体,利用XRD、BET-N₂、TEM/HRTEM、Raman、O₂-TPD和H₂-TPR等表征手段进行表征,并利用连续流固定床反应法研究各催化剂对甲苯的催化氧化性能.结果表明,CeO₂纳米棒因具有高比表面积和细颗粒尺寸,且表面主要暴露高活性的{100}/{110}晶面,拥有更多的氧空位和高活性氧物种,因此,催化活性最高,CeO₂纳米颗粒次之,立方体最低.原位红外甲苯催化氧化机理分析进一步表明,CeO₂纳米颗粒和纳米立方体上生成的羧酸盐物质难以进一步深度氧化,而纳米棒能在贫氧和低温条件下诱导甲苯的完全氧化和产物脱附,使甲苯得以快速降解.

Abstract：Ceria nanorods, nanoparticles and nanocubes catalysts were fabricated by a simple hydrothermal method, and their catalytic performances were evaluated for toluene oxidation in a continuous fixed bed reactor. The properties of the synthesized catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption (BET), transmission electron microscopy/high-resolution transmission electron microscopy (TEM/HRTEM), Raman, oxygen temperature-programmed desorption (O₂-TPD) and hydrogen temperature-programmed reduction (H₂-TPR). The results indicated that ceria nanorods showed greater surface area, smaller crystallite size and more reactive {100} and {110} planes exposure on the surface, giving more oxygen vacancies and reactive oxygen species compared to Ceria nanoparticles and nanocubes., These led to the highest catalytic activity towards toluene oxidation. Furthermore, the mechanism of adsorption-oxidation of toluene via in-situ IR was investigated. The results indicated that it was difficult to further oxidize the intermediates and carboxylate that were generated on ceria nanoparticles or nanocubes. In comparison, it was easier to achieve complete oxidation of toluene and product desorption on nanorods in the lean oxygen at low temperature, favoring the rapid degradation of toluene.