【摘要】 采用两相法合成出含活性组分Au的辛烷基硫醇单层保护Au纳米粒子(C8AuNPs)的正己烷溶胶,用"逐次浸润"法将C8AuNPs负载在γ-Al2O3上,经真空干燥及活化处理制得Au/γ-Al2O3催化剂.所制得的Au催化剂前体C8AuNPs/γ-Al2O3表面Au粒子平均粒径可控制在2-3nm范围内,且分布比较单一;催化剂活性评价600h后,其表面Au的粒径仍主要分布在2-4nm范围内;真空干燥温度影响Au催化剂的粒子尺寸和催化活性,随着真空干燥温度的提高,Au纳米粒子的粒径增大.将所制备的催化剂用于低温CO氧化反应,催化活性评价结果表明,经25℃真空干燥制得的2.5%(质量分数,w)Au/γ-Al2O3具有较高的活性和长期稳定性,其催化CO完全转化的最低温度为-19℃,在15℃下CO完全转化时Au/γ-Al2O3的单程寿命至少900h;4.0%(w)Au/γ-Al2O3在15℃和进料中含水条件下对CO完全氧化的单程寿命不低于2000h,可见催化剂具有强的抗潮湿中毒特性.综合上述实验结果,讨论了影响Au/γ-Al2O3催化剂活性的可能因素.更多还原

【Abstract】 Octanethiolate self-assembled monolayer-protected gold nanoparticles (C8AuNPs) were synthesized using a two-phase protocol. Au/γ-Al2O3 catalysts for low-temperature oxidation of CO were prepared by depositing C8AuNPs in hexane colloidal solution on γ-Al2O3 using "step-by-step soakage" method and by carrying out vacuum dryness and thermal treatment. For the as-prepared C8AuNPs/γ-Al2O3 catalysts, the majority of the gold nanoparticles deposited on the support was in a narrow size range of 2-3 nm. Even after 600 h of reaction, the gold particles were still in the size range of 2-4 nm. The vacuum dryness temperature affected significantly on the particle size, which increased with raising the vacuum dryness temperature. It was found from the evaluation results of catalytic performances that the 2.5% (mass fraction, w) Au/γ-Al2O3 completely converted CO to CO2 at-19 ℃ and maintained the catalytic activity at nearly 100% CO conversion for at least 900 h at 15 ℃, and the 4.0% (w) Au/γ-Al2O3 maintained the catalytic activity at nearly 100% conversion of CO for at least 2000 h in the presence of the reaction gas containing H2O at 15 ℃. Evidently, the catalyst had higher activity, good long-term stability and strong anti-moisture performance. The effect of possible factors on the catalytic activity of Au/γ-Al2O3 was studied based on the above results.更多还原