Pt/Al₂O₃ and bimetallic PtPd/Al₂O₃ catalysts were prepared via supercritical deposition method using supercritical carbon dioxide. The effects of Pt loading of Pt/Al₂O₃ and Pd addition to Pt/Al₂O₃ on particle size, particle size distribution (PSD) and activity for NO and C₃H₆ oxidation and C₃H₆-selective catalytic reduction (C₃H₆-SCR) were investigated. Pt/Al₂O₃ catalysts were prepared with Pt loadings of 0.6, 1.2 and 2.1 wt% and a bimetallic PtPd/Al₂O₃ catalyst was prepared with total metal loading of 1.4 wt% and Pt:Pd molar ratio of 1.3:1. A small fraction of the particles agglomerated after calcination at 550 °C. Around 98 % of the particles had an average particle size of ∼1 nm. The rest of the particles were larger and average size of these larger particles was ∼10 nm for monometallic catalysts and ∼6.5 nm for PtPd/Al₂O₃. All catalysts were found to be active for NO and C₃H₆ oxidation and C₃H₆-SCR reactions. NO oxidation performance of 1.2 wt% Pt/Al₂O₃ catalyst was the highest. C₃H₆ oxidation activity increased with increasing metal content. Light-off temperature for C₃H₆ oxidation shifted to higher temperature in the presence of NO, suggesting competitive oxidation of C₃H₆ and NO. Concentration profiles indicated that C₃H₆-SCR started when C₃H₆ conversion by oxidation reached 50 %; C₃H₆ was consumed both by oxidation and C₃H₆-SCR at higher conversions.

Pt/Al ₂ O ₃和双金属PtPd/Al ₂ O ₃催化剂采用超临界二氧化碳通过超临界沉积法制备。Pt负载Pt/Al ₂ O ₃和Pd添加到Pt/Al ₂ O ₃对粒度、粒度分布（PSD）和NO和C ₃ H ₆氧化和C ₃ H ₆选择性催化活性的影响研究了还原（C ₃ H ₆ -SCR）。铂/铝₂ O ₃制备了 Pt 负载量为 0.6、1.2 和 2.1 wt% 的催化剂，制备了总金属负载量为 1.4 wt% 和 Pt:Pd 摩尔比为 1.3:1的双金属 PtPd/Al ₂ O _{3催化剂。}一小部分颗粒在 550 °C 煅烧后发生团聚。大约 98% 的颗粒具有约 1 nm 的平均粒径。其余颗粒较大，对于单金属催化剂，这些较大颗粒的平均尺寸约为 10 nm，对于 PtPd/Al ₂ O ₃约为 6.5 nm 。发现所有催化剂对NO和C ₃ H ₆氧化以及C ₃ H ₆ -SCR反应都是有活性的。_{1.2 wt% Pt/Al 2} O的NO氧化性能₃催化剂最高。C ₃ H ₆氧化活性随着金属含量的增加而增加。在 NO 存在下，C ₃ H _{6氧化的起燃温度转移到更高的温度，表明 C 3} H ₆和 NO的竞争性氧化。浓度曲线表明，当 C ₃ H ₆氧化转化率达到 50%时，C ₃ H ₆ -SCR 开始；C ₃ H ₆在较高转化率下被氧化和C ₃ H _{6 -SCR 消耗。}