以氧化鈰溶膠洗積甲醇蒸氣重組催化劑於微型流道反應器之研究

Washcoating Cu Catalyst with CeO2 Sol onto Microchannel Reactor for Steam Reforming of Methanol

葉琇屏(Hsiu-Ping Yeh)

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.2009.00326

摘要

本研究目的乃以組裝後的微型流道反應器透過甲醇蒸氣重組反應產氫，並測定洗積成分及特性，進而探討反應器之功能及耐久性。實驗中以連續沈澱法製備合成的銅鋅鋁催化劑，利用商購之氧化鈰溶膠作為黏著劑洗積在不鏽鋼微流道片上；經過350oC煅燒後，洗積後微流道試片置於超音波震盪器進行破壞試驗，並測得震盪前後的催化劑層重量及其損失率，將漿料附著能力定量化。
藉由光學顯微鏡觀察洗積後試片，可知將乙醇添加在漿料中可得到很好的潤濕效果以幫助塗層均勻，另外從震盪損失數據可知，當漿料中的氧化鈰溶膠比例越高時，其附著度越好。然而在FE-SEM和ESCA的觀察和分析下，過多的氧化鈰溶膠會填塞在催化劑顆粒之間的孔隙且及累積在漿料表面，不利於氣體擴散至催化劑活性位置進行反應，結果使得漿料需要更高的反應溫度才能達到95%的甲醇轉化率。從TPR結果也發現到，氧化鈰溶膠的添加會使得催化劑漿料的還原性較差。
由2%黏著劑含量的漿料所洗積組裝的微流道反應器，在GHSV = 60 kh-1、水醇莫耳比為1.3的進料條件下，可得在240oC時達到95%的甲醇轉化率，在相同催化劑及進料條件下填充床式反應器也可達到相同的反應性。不過在較低溫度時，微流道反應器的反應性優於填充床式反應器，這可能是由於它有較佳的熱傳效應所致。

關鍵字

氧化鈰 ； 洗積 ； 微流道反應器 ； 製氫 ； 甲醇蒸氣重組反應

並列摘要

Microchannel reactors (MCR) are intended to be assembled in this study for production of hydrogen from the steam reforming of methanol (SRM). Catalyst CuO/ZnO-γ-Al2O3 was prepared by the sequential precipitation method to catalyze SRM. Powders of prepared catalysts were subsequently washcoated, onto microchannels of stainless steel plate as active plate for MCR, by cerium oxide sol. After a calcination treatment at 350 oC, the adhesion strength of coated layers was evaluated in term of fraction of weight loss (FL) during a standard erosion of ultra sonification.
Optical microscopic examination noticed that ethanol solvent substantially promoted wetting ability of resulted slurry on S.S 304 substrate and a smooth coated layer. FL was found decreased on increasing the binder content (B) in coated slurries. However, temperature required for 95% conversion of methanol (T95) also increased with B. FE-SEM and ESCA characterization suggested that particles of oxide sol tended to fill into pores among catalyst powders and partially covered active sites of catalyst. Temperature programmed reduction also found a shift of reduction of copper oxide to high temperatures by the binder.
A T95 = 240 oC was found MCR, with an active plate coated with a slurry of B = 2, at a SRM condition of WHSV = 16.2 and steam to methanol ratio of 1.3. A same T95 was found from a packed bed reactor (PBR) using a same catalyst. However, high methanol conversion was generally found from MCR at low reaction temperatures. The advantage of MCR was attributed to its efficient transfer of heat.

並列關鍵字

Cerium oxide ； Washcoating ； Microchannel reactor ； Hydrogen production ； Methanol steam reforming

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