A comparison of the esterification of acetic acid with methanol using heterogeneous versus homogeneous acid catalysis
A comparison of the esterification of acetic acid with methanol using heterogeneous versus homogeneous acid catalysis
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DOI：
10.1016/j.jcat.2006.05.026
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发表时间：
2006-09-10
影响因子：
7.3
通讯作者：
Goodwin, James G., Jr.
中科院分区：
文献类型：
--
作者：
Liu, Yijun;Lotero, Edgar;Goodwin, James G., Jr.
为了研究均相和非均相催化酯化反应的异同，分别采用商用NH3/SiO2纳米复合催化剂（SAC-13）和H2SO 4研究了乙酸与甲醇的酯化反应动力学。反应在60 ° C下在等温充分混合的间歇反应器中进行。进行有机碱滴定、TGA和元素硫分析以估计SAC-13的酸位点密度，从而允许基于每个位点评估其用于酯化的催化性能。发现SAC-13具有与H_2SO_4相当的乙酸酯化活性中心。SAC-13和H_2SO_4由于水的存在也表现出类似的反应抑制。对水的存在的类似响应和吡啶中毒实验的结果表明，与这些催化剂的酯化反应通过共同的反应机理发生。SAC-13上的反应似乎与假设的非对称型反应机制一致，涉及单中心催化，可能存在速率控制的Eley-Rideal表面反应。机理推导的动力学模型成功地预测了SAC-13的酯化率随着反应的进展。讨论了均相和非均相酸催化酯化反应的区别。(c)2006年爱思唯尔公司All rights reserved.
To investigate the similarities and differences between heterogeneous and homogeneous catalyzed esterification, the kinetics of acetic acid esterification with methanol were investigated using a commercial Nalion/silica nanocomposite catalyst (SAC-13) and H2SO4, respectively. Reactions were carried out in an isothermal well-mixed batch reactor at 60 degrees C. Organic base titration, TGA, and elemental sulfur analysis were carried out to estimate the acid site density of SAC-13, permitting the assessment of its catalytic performance for esterification on a per site basis. It was found that SAC-13 has comparable site activity for acetic acid esteritication as H2SO4. SAC-13 and H2SO4 also exhibited similar reaction inhibition due to the presence of water. The similar response to the presence of water and the results of pyridine poisoning experiments suggest that esterification with these catalysts occurs through a common reaction mechanism. Consistent with the hypothesized homogeneous-type reaction mechanism, reaction on SAC-13 appears to involve single-site catalysis with a probable rate-controlling Eley-Rideal surface reaction. A mechanistically derived kinetic model successfully predicts the esterification rate of SAC-13 as reaction progresses. The dissimilarities between homogeneous and heterogeneous acid-catalyzed esterification are also discussed. (c) 2006 Elsevier Inc. All rights reserved.