The synthesis route of 10Al2O3·2B2O3 (10A2B) and effect of additives were studied to use this compound as a thermally stable support material for Pd catalysts. The preparation by reverse coprecipitation was found to have a beneficial effect on the BET surface area of 10A2B and thus Pd metal dispersion, compared to other preparation routes via solid-state reaction and hydrolysis of metal alkoxides. The addition of 3 wt % BaO suppressed the sintering of 10A2B and Pd during thermal aging at 900 °C in a stream of air containing 10% H2O. Although direct interactions between Pd and the support material were not detected by EXAFS, the catalytic performance for NO–CO–C3H6–O2–H2O reactions under modulated air-to-fuel ratio (A/F) conditions was strongly influenced by the Ba additive. The activity for NO and C3H6 in a rich region (A/F < 14.6) was especially enhanced in the presence of Ba because of accelerated elemental reactions including NO–CO and NO–C3H6. In situ FT-IR of CO suggested that the Pd electronic state changed by electrostatic effect of Ba additives would activate NO and weaken the self-poisoning effect of C3H6.
研究了 10
Al2O3-2B2O3 (10A2B) 的合成路线和添加剂的影响,以便将这种化合物用作
钯催化剂的热稳定支撑材料。与其他通过固态反应和
金属烷氧基化合物
水解的制备路线相比,反向共沉淀法制备 10A2B 对 10A2B 的 BET 表面积以及
钯金属分散具有有利影响。在含有 10%
H2O 的气流中,温度为 900 °C 时,添加 3 wt % 的 BaO 可抑制 10A2B 和 Pd 的烧结。虽然 EXAFS 没有检测到
钯和支撑材料之间的直接相互作用,但在调节空气燃料比 (A/F) 条件下,
钡添加剂对 NO-CO-
C3H6-O2- 反应的催化性能有很大影响。由于元素反应(包括 NO-CO 和 NO- )的加速,富集区(A/F < 14.6)的 NO 和 活性在钡的存在下尤其得到了提高。CO 的原位傅立叶变换红外光谱表明,钡添加剂的静电效应改变了
钯的电子状态,从而激活了 NO 并削弱了 的自毒作用。