鈷硼觸媒合成條件對硼氫化鈉反應器設計之影響

Effects of Co-B catalysts synthesis conditions on sodium borohydride hydrolysis reactors design

潘泉亦(Chuan-Yi Pan)

指導教授 ： 陳逸航

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2013年)

https://doi.org/10.6846/TKU.2013.00362

摘要

本研究探討鈷硼觸媒合成條件與觸媒表面結構、觸媒動力學參數與硼氫化鈉水解反應器設計及操作的關係。以離子交換樹脂作為觸媒載體，硼氫化鈉為還原劑，使用離子交換法及化學還原法進行鈷硼觸媒合成。觸媒合成條件之變數為:還原溫度、還原劑濃度、還原劑pH值、還原劑添加速率以及離子交換樹脂種類。結果顯示，因水解反應及還原反應相互競爭，低還原溫度時還原速率慢，觸媒表面形成緊密排列且樹枝狀的結構，觸媒表面積較大。低溫還原之觸媒在水解產氫上有較好的表現。以L-H動力學模式進行實驗數據進行回歸，得到頻率因子、活化能、40 oC下吸附常數分別為1.17x109mol/g-min、70.65 kJ/mol、6.8 L/mol。更換載體離子交換樹脂為TP-207，以相同變數進行觸媒合成，Co-B/TP-207比上Co-B/IR-120有較高的觸媒負載量、更快的產氫速率以及更好的耐久性。以此觸媒設計硼氫化鈉產氫三相反應器尺寸，並建立數模式，分析系統之反應溫度、進料濃度、進料流率對於反應器出口氫氣流率之影響，並選定進料流率來操控出口氫氣流率。在80oC操作下，I-1至I-4觸媒中，以I-4觸媒有最大的可操作範圍。

關鍵字

鈷硼觸媒 ； 硼氫化鈉 ； 動力學參數 ； 水解反應 ； 化學還原法

並列摘要

The objective of this work is to study the effect of various Co-B catalyst synthesis conditions on the catalyst surface morphology and kinetic parameters. The Co/B catalyst was synthesized on IR-120/TP-207 resin surface by using ion exchange and chemical reduction method using NaBH4 as a reduction agent. The reduction conditions which were investigated here were: reduction temperature, NaBH4 concentration, pH value, NaBH4 adding flow rate and different types of resins. The result shows reduction temperature gives the most dramatic effect on surface morphology which is caused by competing reactions of reduction and hydrolysis. Low reduction temperature resulted in a slower Co/B reduction rate and made the catalyst surface denser with a branched structure. This created more surface area than higher reduction temperatures. Low reduction temperature catalyst had the better performance on NaBH4 hydrolysis reaction for hydrogen generation rate. The optimal reduction temperature of the Co-B/IR-120 is 25 oC. The L-H model was used to regress kinetic parameters from the experiment data. The frequency factor, activation energy and adsorption constant are 1.17x109 mol/g-min, 70.65 kJ/mol, and 6.8 L/mol at 40oC, respectively. Finally, the TP-207 resin was used instead of IR-120. After scanning for all catalyst synthesis conditions, the Co-B/TP-207 had the higher catalyst loading, faster hydrogen generation rate and more durability than Co-B/IR-120. A mathematical model was built to design the NaBH4 hydrolysis reactor for hydrogen generation. The operating variables of the system are: reaction temperature and NaBH4 inlet concentration, inlet flowrate. From sensitivity analysis, the dominant variable of the hydrogen generation system is NaBH4 inlet flowrate. The I-4 catalyst shows the better operability at 80oC than other Co-B/IR-120 catalyst.

並列關鍵字

Sodium borohydride ； Co-B catalyst ； Kinetic parameters ； Hydrolysis reaction ； Chemical reduction method

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