Prodical Application of Environmental Catalysis through the Chemical Vapor Deposition of Silica

提高Pd/沸石催化剂在水蒸气存在下对NO-CH_4-O_2反应的催化活性和耐久性是一个重要课题。通过化学气相沉积（CVD）对沸石外表面进行SiO_2单层改性，由于沸石外表面产生疏水特性，使得沸石的耐久性能得到了很大的提高。在Pd/沸石中加入Ag、Mn可提高初始NO还原活性。ZSM-5外表面SiO_2层的加入效应和CVD效应的结合，使Pd在NO-CH_4-O_2反应中的活性和耐久性都得到了提高。为工业上应用硅单层固体酸催化剂，提出了在γ-氧化铝上连续流化学气相沉积四甲基氧基硅烷的方法。与静态反应器相比，流动反应器的硅覆盖相对不均匀，特别是在低硅浓度区域。然而，在高硅浓度区域，结构差异很小，覆盖率几乎达到100%。两种方法得到的1-丁烯双键异构化的催化活性和热稳定性相似，表明连续流法足以工业化制备二氧化硅单层催化剂。采用化学气相沉积法对硅石晶体进行了硅（OCH_3）_4的沉积，以控制晶体的孔径大小。用重量法和色谱法研究了硅质岩和cvd硅质岩对烷烃的吸附。通过选择硅石上硅沉积的程度，可以分离出直链烷烃和支链烷烃。

The improvement of the catalytic activity and durability of Pd/zeolite catalyst for the NO-CH_4-O_2 reaction in the presence of water vapor is an important subject. We found that the much improvement in the durability was attained by the modification of the external surface of zeolite with SiO_2 monolayer through the chemical vapor deposition (CVD) due to the generation of the hydrophobic character in the external surface of zeolite. The initial activity for NO reduction was increased by the addition of the Ag, Mn into the Pd/zeolite. The combination of the addition effect of and CVD of SiO_2 layer over ZSM-5 external surface resulted in the improvement in both activity and durability of Pd for NO-CH_4-O_2 reaction.A continuous-flow method of chemical vapor deposition of tetramethoxysilane on γ-alumina was developed for industrial utilization of silica monolayer solid-acid catalyst. The flow method caused relatively heterogeneous coverage of silicon compared to static reactor especially in the low silicon concentration region. However, the difference in the structure was small in the high silicon concentration region where the coverage arrived at almost 100%. The catalytic activity for double-bond isomerization of 1-butene and thermal stability obtained by the two methods were similar, showing that the continuous flow method was sufficient to prepare the silica monolayer catalyst industrially.Chemical vapor deposition of Si(OCH_3)_4 was carried out on silicalite crystals in order to control the pore-opening size. Adsorption of alkanes on silicalite an CVD-silicalite was performed gravimetrically and chromatographically. It was found that the linear and branched paraffins could be separated by choosing the extent of silica deposition on silicalite.