等离子体与Cu-Pd/S-1催化剂协同催化甲烷转化制低碳烯烃

采用等体积浸渍法制备了Pd、Cu-Pd改性的S-1催化剂，利用介质阻挡放电（DBD）等离子体反应器研究了甲烷无氧转化制低碳烯烃（C₂~C₄⁼）的性能，重点关注了乙烯的产量。探讨了Ar的添加和特定输入能量（SIE）对甲烷转化率以及产物分布的影响。实验结果表明，等离子体与催化剂协同催化与仅使用等离子体相比性能更优异，使乙烯选择性提高了3.1倍，C₂~C₄⁼的选择性提高了2.7倍；与S-1相比，Pd/S-1具有更高的乙烯选择性，这是因为在S-1上负载金属Pd有助于乙炔原位加氢生成乙烯；适宜的Pd负载量有利于提高烯烃选择性，而过高的Pd负载量倾向于不饱和烃的连续加氢，导致了烷烃的生成；与单金属Pd改性相比，Cu-Pd双金属改性抑制了乙烯的进一步加氢，提高了乙烯的选择性。通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高倍透射电子显微镜（HRTEM）、X射线粉末衍射（XRD）、X射线光电子能谱（XPS）对催化剂进行了表征分析。结果表明，Cu的加入使自身电子向Pd转移，增加了Pd电子密度；另外，Cu的存在提高了Pd的分散性。以2Cu-0.1Pd/S-1为催化剂时可以得到更优异的反应性能。

Synergistic catalysis of methane to light olefins by plasma and Cu-Pd/S-1 catalyst

The Pd or Cu-Pd modified S-1 catalyst was prepared by an equivalent volume impregnation method. A dielectric barrier discharge (DBD) plasma reactor was used to study the nonoxidative conversion of methane to light olefins (C₂—C₄⁼), focusing on the production of ethylene. The effects of the Ar addition and specific input energy (SIE) on methane conversion and product distribution were investigated. The experimental results showed that the catalytic performance of plasma-catalyst cooperation was better than that of plasma-only mode. The selectivity of ethylene was increased by a factor of 3.1 and the selectivity of C₂—C₄⁼ was increased by a factor of 2.7. Compared with S-1, Pd/S-1 provided higher ethylene selectivity. This is because the metal Pd supported on S-1 promoted the in-situ hydrogenation of acetylene to ethylene. The suitable Pd loading was beneficial towards achieving higher olefins selectivity, while excessive Pd loading caused continuous hydrogenation of unsaturated hydrocarbons so that the production was alkanes. Compared with single metal Pd modification, Cu-Pd bimetal modification inhibited further hydrogenation of ethylene and improved the selectivity of ethylene. The catalysts were characterized by using SEM, TEM, HRTEM, XRD, XPS. The results showed that the addition of Cu transferred its own electrons to Pd, which increased the electron density of Pd. In addition, the presence of Cu improved the dispersibility of Pd. Better reaction performance were obtained with the 2Cu-0.1Pd/S-1 catalyst.