负载型钯催化剂上碳对甲烷燃烧活性的影响(英文)

以ＥＤＴＡ为碳源分别引入到γ－Ａｌ２Ｏ３和５％ＭｇＯ／γ－Ａｌ２Ｏ３担载的Ｐａ（ＮＯ３）２催化剂上，且分别标示为Ｐａ（ＮＯ３）２／［ｓｕｐｐｏｒｔ＋ ＥＤＴＡ］和［Ｐａ（ＮＯ３）ｚ／ｓｕｐｐｏｒｔ］＋ ＥＤＴＡ，它们分别是通过改变ＥＤＴＡ对载体的浸渍次序而制备的。用上述仅经过干燥处理的催化剂进行甲烷燃烧反应并对不同反应阶段的催化剂样品进行ＸＰＳ分析。结果发现，引入到催化剂上的ＥＤＴＡ在富氧气氛下，随着温度的升高，原位被自然氧化．部分变成ＣＯ２而逸出，部分成焦而沉积在钯或载体上。在反应过程中有Ｐｄ－Ｃ固体溶液生成。外来的碳无论其存在形式或在催化剂上的位置如何，都显著有碍于甲烷燃烧，使负载的Ｐａ（ＮＯ３）２催化剂变得更不活泼。同时也讨论了在甲烷燃烧反应过程中碳对钯形貌变化的影响。

EFFECT OF FOREIGN CARBON ON ACTIVITY OF METHANE COMBUSTION OVER SUPPORTED PALLADIUM CATALYSTS

EDTA as precursor of carbon was introduced into Pd(NO3)2 catalysts supported on (-Al2O3 or 5%MgO/(-Al2O3. Two kinds of samples, denoted as Pd(NO3)2/support EDTA] and Pd(NO3)2/support] EDTA, were prepared by changing sequence of impregnating EDTA to the supports. After only being dried they were tested for methane combustion. XPS analyses to the samples at different stages of testing reaction were performed. It was found that the Pd(NO3)2 catalysts became more inactive due to the introduction of EDTA. EDTA in the catalysts was naturally in situ oxidized, partially became into CO2 and escaped, partially coked and deposited on palladium and support with temperature increasing in oxygen-rich atmosphere. Formation of Pd-C solid solution was also confirmed during the reaction. It can be suggested that foreign carbon, in spite of its any existing forms and position in catalysts, inhibits methane combustion largely. The role of carbon on morphological change of palladium during methane combustion was also discussed.