High-loading silica-encapsulated PdPt catalysts ([email protected]₂, 4 wt.% Pd, 7 wt.% Pt) are synthesized using a Stöber-based method and are tested in lean methane combustion in the presence of water up to 550 °C. The as-synthesized bimetallic core particles have an average size of 7 nm, are uniform alloys of Pd and Pt, and are well-dispersed inside the oxide shells. The SiO₂ shells are about 60 nm in diameter, with a specific surface area of 600 m²/g and a median pore diameter of 3.4 nm. The catalyst shows a stable methane conversion during a hydrothermal ageing (HTA) test which is two- and ten-fold higher than the conversion for the impregnated Al₂O₃ and SiO₂-supported catalysts of the same metal loading, respectively. The surface area of the porous shell remains unaffected after HTA; however, the metal dispersion evaluated by CO chemisorption increases after the ageing and some changes in the morphology of the bimetallic PdPt nanoparticles occur.

高载二氧化硅封装PDPT催化剂（[电子邮件保护] ₂，4重量％的Pd，7重量％的Pt）使用的是基于STOBER-方法合成和在贫甲烷燃烧中的水向上存在下550进行测试℃。合成后的双金属核颗粒平均尺寸为7 nm，是Pd和Pt的均一合金，并且很好地分散在氧化物壳内部。SiO ₂壳的直径为约60nm，比表面积为600m ² / g，中值孔径为3.4nm。该催化剂在水热老化（HTA）测试期间显示出稳定的甲烷转化率，该转化率比浸渍的Al ₂ O ₃和SiO ₂的转化率高2到10倍负载的相同金属负载的催化剂。HTA后，多孔壳的表面积保持不变；然而，在老化后，通过CO化学吸附评估的金属分散度会增加，并且双金属PdPt纳米粒子的形态会发生一些变化。