氧化鋯溶膠洗積甲醇蒸氣重組催化劑於微流道反應器之研究

Washcoating Copper Catalyst with Zirconia Sol onto Microchannel Reactor for Steam Reforming of Methanol

潘承煜(Cheng-Yu Pan)

指導教授 ： 林錕松

共同指導教授 ： 葉君棣(Chuin-Tih Yeh)

元智大學/工程學院/化學工程與材料科學學系/碩士(2009年)

https://doi.org/10.6838/YZU.2009.00317

摘要

甲醇蒸氣重組反應是一個可應用於燃料電池上的產氫反應，而本研究乃發展以此反應為基礎的微流道反應器。與填充床相比，微流道反應器有低壓降、不易爆炸、快速的熱傳與質傳等優點。具有反應活性的流道片是此反應器的核心，文獻上常以氧化物溶膠當黏著劑與催化劑粉末混合成漿料後，洗積於流道片上而製得。
本研究試著以市售氧化鋯溶膠作為黏著劑，與銅鋅鋁催化劑混合製成漿料後，洗積於微流道片上使其具催化反應性。之後，以超音波震盪時的重量損失率來評估漿料與基材間的附著性；催化活性則以甲醇蒸氣重組反應時的甲醇轉化率為95%所需的溫度(T95)來評估。附著實驗發現當漿料的pH ≦ 5時，可獲得較低的重量損失率，但隨著鹼度增加損失率亦隨之增加。黏度測試顯示，損失率增加的原因是漿料在製作過程中膠化所導致。因此，漿料必須維持在酸性以維持其附著性。但是在pH ≦ 5的情況下，催化劑會明顯地被酸溶解，使得該洗積層約在300oC時才能達到95%的甲醇轉化率。
為了提升甲醇蒸氣重組反應的反應性，本研究嘗試以不含酸的醇氧鋯溶液作為黏著劑並製作成微流道反應器。觸媒活性測試顯示其反應性確實比利用市售氧化鋯溶膠的來得高，因此T95明顯地降低至240oC。

關鍵字

氧化鋯溶膠 ； 洗積 ； 銅鋅鋁催化劑 ； 微流道反應器 ； 甲醇蒸氣重組反應 ； 燃料電池

並列摘要

Steam reforming of methanol (SRM) is a reaction which may produce hydrogen for fuel cell application. In this study, micro-channel reactors (MCR) for SRM reaction are under developing. The micro-channel reactor generally has advantages of low pressure drop, low probability of explosion, and fast in thermal and mass transfer. The heart of micro-channel reactors is active plates which were fabricated in the literature by washcoating powders of active catalyst onto stainless steel plates (SSP) with metal oxide sols.
The present study intended to mix SRM catalyst (Cu/ZnO/Al2O3) with a commercial ZrO2 sol into slurries and brush them onto SSP for active plates. The binding strength of slurries on SSP was estimated by fraction of weight loss (FL) in an ultrasonic vibration test. The performance of assembles MCR was estimated from temperature required for 95% methanol conversion (T95) in SRM reaction. Experimentally, FL was found low at pH ≦ 5 but increased drastically on increasing the basicity of prepared slurries. Viscosity characterization revealed that the FL increase was resulted from a formation of gel upon storage. Therefore, the slurry prepared in the acidic condition is necessary to exhibit the adhesive ability. Unfortunately, a significant dissolution of catalyst was found in slurries with pH ≦ 5 and active plates coated in such condition required a high reaction temperature of T95 ~ 300oC from the SRM test.
In order to improve SRM activity of MCR, a none-acidic binder was prepared by dissolving zirconia alkoxide in 1-propanol. The SRM test revealed that active plates coated by this binder indeed exhibited much better catalytic activity than those coated with the commercial ZrO2 sol. Consequently, T95 was significantly decreased to 240oC.

並列關鍵字

zirconia sol ； washcoating ； Cu/ZnO/Al2O3 catalyst ； microchannel reactor ； steam reforming of methanol ； fuel cell

參考文獻

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