以鋁粒分散商業觸媒進行甲醇水蒸氣重組器操作性能之研究

Performance Study of Methanol Steam Reformer using Commercial Catalyst Dispersed by Aluminum Beads

湯竣凱(Jiun-Kai Tang)

指導教授 ： 張志雄

大同大學/工程學院/化學工程學系所/碩士(2007年)

摘要

在甲醇水蒸氣重組反應中，由於本反應是高吸熱反應因而需要大量的熱能以維持反應進行，所以如何讓熱能能夠迅速的傳遞到觸媒本身就顯得格外重要。為了讓熱量能夠迅速的從外部傳遞到觸媒本身，本研究針對不同熱傳介質之熱傳能力進行實驗，並探討其影響甲醇轉化率及CO選擇率的影響。我們首先比較鋁粒與r-Al2O3作為熱傳介質分別與商業觸媒MDC均勻混合進行甲醇蒸氣重組。在固定操作條件下（水與甲醇之莫耳比（S/C）為1，反應溫度維持在250℃時），探討不同熱傳介質對甲醇轉化率與CO選擇率的影響。由實驗結果可得知，使用鋁粒分散觸媒不但可增加熱傳能力並提升觸媒的反應性，使甲醇轉化率改善以獲得更高產量的氫氣，雖然鋁粒在熱傳的表現明顯優於r-Al2O3，但產物中CO選擇率卻略為偏高。
另外以全因子實驗設計安排MDC觸媒於床體上下部不同配置與溫控量測點在上下部床體的不同位置進行實驗以探討甲醇重組反應的表現差異。由實驗結果可以得知當Wc/F範圍大於0.011 (kg s/mmol)時，使用觸媒均勻分布；Wc/F範圍小於0.011時使用上半部觸媒量少、溫度控制在頂部可以得到較好的反應表現。

關鍵字

鋁粒

並列摘要

In a methanol steam reformer, the endothermic reactions are carried out, therefore, a large quantity of energy needs to provide in time to maintain the reactions at a constant temperature. In order to transfer the heat from the heat source usually located at the outer of the reactor tube into the catalyst bed in the reactor, we evaluate the heat transfer capability of the available catalyst dispersion mediums including the aluminum beads and r-Al2O3. The reforming reactions were carried out in a tubular reactor packed with the commercial MDC III catalysts and the adopted dispersion medium to study the effects of dispersion medium on the conversion of methanol and the selectivity of CO over CO2 at the same operating conditions (the ratio of water over methanol (S/C) equals to one, the operating temperature equals to 250℃). The experimental results show that adopting the aluminum beads can not only improve the heat transfer capability but also increase the methanol conversion to obtain a higher hydrogen production rate, although the CO selectivity in the product stream is some how higher than the reactions carried out adopting the r-Al2O3 as the dispersion medium.
Furthermore, the full factor experimental design was applied to carry out the experiments to study the effects of the control factors (The first control factor was different catalyst loading at the upper and lower section of the reactor, while the second control factor was the location the temperature sensor at the upper and lower section of the reactor) on the performance of the reformer. On the basis of the defined objective function (the desirability in terms of the cumulative quantities of hydrogen and CO production), the experimental results show that it is incentive to adopt a uniformly distributed catalysts with the dispersion medium when Wc/F is greater than 0.011(kg s/mmol) . Otherwise, it is more incentive to adopt the paring of the operating control factors: the upper section of the reactor is loaded with less catalysts and the temperature is located at the upper section.

並列關鍵字

Aluminum beads

參考文獻

Agarwal, V.; Patel, S.; Pant, K. K. “H2 production by steam reforming of

methanol over Cu/ZnO/Al2O3 catalysts: transient deactivation kinetics

modeling”, Appl. Catal. A. 2005, 155, 279.

Catalytic Steam Reforming of Methanol Part 2: Kinetics of Methanol

a Cu/ZnO/Al2O3 catalyst: a kinetic analysis and strategies for suppression