改性不同形貌天然黏土负载纳米金催化剂的制备及催化性能研究

Preparation of modified natural clay supported gold nanoparticles catalyst and study on its catalytic properties

以有机硅烷接枝改性埃洛石纳米管(HNTs)和层状高岭土(Kaolin)为纳米金的载体、氯金酸为前体,通过液相还原法制备得到负载型金催化剂。以环己烷液相选择性氧化为模型反应,考察了还原剂的种类和载体的形貌对金催化剂催化性能的影响。结果表明,当纳米金的理论负载质量分数为1.5%时,以管状埃洛石为载体、NaBH4为还原剂制备得到的金催化剂样品1.5%Au/AE-HNTs上纳米金呈高度分散状态,平均粒径为2.6 nm;在模型反应中催化氧化性能较好,其中KA油的选择性达到83.06%,环己烷的转化率达到9.6%,且XPS表征结果显示Au0为主要催化活性价态。

The supported nano-gold catalysts are obtained through liquid phase reduction method by using organosilane modified halloysite nanotubes( HNTs) and layered kaolin as carriers,and chloroauric acid as precursor.The liquid phase selective oxidation of cyclohexane is taken as a model reaction,the effects of the type of reducing agent and the morphology of carriers on the catalytic performance of the catalyst are investigated. It turns out that nano-gold disperses highly on the prepared 1. 5% Au/AE-HNTs,with an average particle size of 2. 6 nm only when the theoretical load of nano-gold is 1. 5 wt%,tubular HNTs is used as the carrier,and NaBH4 is used as reducing agent.The 1. 5% Au/AE-HNTs catalyst exhibits better catalytic oxidation performance in the model reaction,over which,the selectivity of KA oil reaches 83. 06%,and the conversion of cyclohexane reaches 9. 6%.XPS characterization results show that Au0 is the main catalytic active valence state.