Taheraslani Mohammadreza, Gardeniers Han
Mesoscale Chemical Systems, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Nanomaterials (Basel). 2019 Apr 10;9(4):589. doi: 10.3390/nano9040589.
The deposits formed during the DBD plasma conversion of CH₄ were characterized by high-resolution scanning electron microscopy (HRSEM) and energy dispersive X-ray elemental analysis (EDX) for both cases of a non-packed reactor and a packed reactor. For the non-packed plasma reactor, a layer of deposits was formed on the dielectric surface. HRSEM images in combination with EDX and CHN elemental analysis of this layer revealed that the deposits are made of a polymer-like layer with a high content of hydrogen (60 at%), possessing an amorphous structure. For the packed reactor, γ-alumina, Pd/γ-alumina, BaTiO₃, silica-SBA-15, MgO/Al₂O₃, and α-alumina were used as the packing materials inside the DBD discharges. Carbon-rich agglomerates were formed on the γ-alumina after exposure to plasma. The EDX mapping furthermore indicated the carbon-rich areas in the structure. In contrast, the formation of agglomerates was not observed for Pd-loaded γ-alumina. This was ascribed to the presence of Pd, which enhances the hydrogenation of deposit precursors, and leads to a significantly lower amount of deposits. It was further found that the structure of all other plasma-processed materials, including MgO/Al₂O₃, silica-SBA-15, BaTiO₃, and α-alumina, undergoes morphological changes. These alterations appeared in the forms of the generation of new pores (voids) in the structure, as well as the moderation of the surface roughness towards a smoother surface after the plasma treatment.
在非填充反应器和填充反应器两种情况下，通过高分辨率扫描电子显微镜（HRSEM）和能量色散X射线元素分析（EDX）对CH₄的DBD等离子体转化过程中形成的沉积物进行了表征。对于非填充等离子体反应器，在介电表面形成了一层沉积物。结合该层的EDX和CHN元素分析的HRSEM图像表明，沉积物由氢含量高（60原子%）的聚合物状层组成，具有无定形结构。对于填充反应器，γ-氧化铝、Pd/γ-氧化铝、BaTiO₃、二氧化硅-SBA-15、MgO/Al₂O₃和α-氧化铝被用作DBD放电内部的填充材料。暴露于等离子体后，在γ-氧化铝上形成了富含碳的团聚物。EDX映射进一步表明了结构中富含碳的区域。相比之下，对于负载Pd的γ-氧化铝，未观察到团聚物的形成。这归因于Pd的存在，它增强了沉积物前驱体的氢化作用，并导致沉积物的量显著降低。还进一步发现，包括MgO/Al₂O₃、二氧化硅-SBA-15、BaTiO₃和α-氧化铝在内的所有其他等离子体处理材料的结构都发生了形态变化。这些变化表现为结构中产生新的孔隙（空隙），以及等离子体处理后表面粗糙度向更光滑表面的适度变化。
