【摘要】 在高温催化燃烧中烧结对催化剂的活性影响巨大,而火焰合成的纳米催化剂的烧结行为鲜有研究.通过火焰喷雾热解合成了以TiO2、ZrO2、Si O2为载体的一系列Cu基负载型纳米催化剂,并将所合成的纳米颗粒用于低浓度CH4催化燃烧以评价其性能.对比反应前后催化剂的BET、XRD及TEM表征,研究了不同催化剂材料在高温催化过程中晶相转变与烧结之间的竞争关系,并发现了CuO-ZrO2的表面扩散主导以及Cu O-TiO2的晶界扩散主导的烧结机制.从催化燃烧测试分析发现,CuO-ZrO2在600℃对甲烷的催化转化率达到了90%,Cu O-TiO2由于其抗烧结性能较差在800℃才达到88%转化率,而Cu O-Si O2反应性最差,在600℃只有30%转化率.结果表明,ZrO2负载型Cu基纳米催化剂活性较高兼具抗烧结性能.更多还原

【Abstract】 The activity of catalysts is substantially influenced by their sintering behaviors during the high temperature catalytic combustion. However,few studies have focused on the sintering behaviors of nano-catalysts prepared by flame synthesis. In this paper,Cu-based catalysts with supports of TiO₂,ZrO₂ and SiO₂ were synthesized via flame spray pyrolysis（FSP）,which were further applied to the catalytic combustion experiment of lowconcentration CH₄. The characterizations by BET,XRD and TEM were also compared before and after the reaction to study the competition between the transformation of crystal-phase and particle sintering in different catalysts during the high-temperature catalysis. The sintering mechanism was revealed,in which CuO-ZrO₂ was dominated by surface diffusion while CuO-TiO₂ by crystal diffusion. The activity test showed that CuO-ZrO2 obtained 90% CH4 conversion at 600 ℃. Due to the deficiency of anti-sintering,CuO-TiO₂ reached 88% conversion at 800 ℃. The CH4 conversion of 30% was achieved at 600 ℃ by inactive CuO-SiO2. Results showed that the ZrO₂-supported Cu-based nano-catalysts demonstrated both good anti-sintering performance and higher activity for the CH₄ catalytic combustion.更多还原