处理方法对多壁碳纳米管结构及负载Ru催化剂氨分解反应活性的影响

分别用H_2O_2、强碱(NaOH、 KOH)和强酸HNO_3处理CNTs.以处理后的CNTs为载体、通过浸渍RuCl_3水溶液结合高温H_2还原制备Ru/CNTs催化剂,并将其应用在氨分解催化反应中.利用XRD、 TPR、 TPD-MS表征手段研究了Ru在CNTs表面的分散、还原性能及CNTs表面化学基团,探究催化剂结构-性能间构效关系.结果表明,强碱及双氧水处理CNTs,为其表面引入了数量适宜的羧基、酸酐、酚等官能团,而传统硝酸处理则引入了大量的羧基、酸酐、酯、内酯、酚、醌和羰基等官能团,对CNTs本征结构性质影响很大.经强碱及双氧水处理CNTs上负载Ru后所得催化剂的效果明显优于传统硝酸处理CNTs上负载Ru催化剂.我们发展的CNTs的新型处理方法为研制高活性Ru/CNTs催化分解氨催化剂提供了新的思路.

Effects of Treatment Methods on Structure of Multi-walled Carbon Nanotubes and Activity of Supported Ru Catalyst for Ammonia Decomposition

H₂O₂, strong base (NaOH, KOH) and nitric acid HNO₃ were respectively used to treat CNTs. With the modified CNTs as the support, Ru/CNTs catalysts were prepared by impregnating the support with the aqueous solution of RuCl₃ and reducing by H₂ at high temperature, then the prepared catalysts were applied in the decomposition of ammounia. The dispersion and reduction properties of Ru on CNTs, as well as the chemical groups on CNTs surface were studied by XRD, TPR and TPD-MS characterization techniques. The structure-activity relationship between the structure and performance of the catalyst were explored. The results showed that the treatment of CNTs with strong alkali and hydrogen peroxide introduced a suitable number of functional groups such as carboxyl, anhydride and phenol on the surface, while the traditional nitric acid treatment introduced a large number of functional groups such as carboxyl, anhydride, ester, lactone, phenol, quinone and carbonyl, which greatly affected the intrinsic structure and properties of CNTs. The catalytic activities of Ru supported on CNTs treated with strong alkali and hydrogen peroxide are better than that of Ru supported on CNTs treated with nitric acid. This study provides a new idea for the new treatment method of CNTs, the analysis method of surface chemical functional groups on CNTs and the improvement of the catalytic activity of Ru/CNTs for ammonia decomposition.