An efficient two-phase reaction of ethyl acetate production in modified ZSM-5 zeolites
An efficient two-phase reaction of ethyl acetate production in modified ZSM-5 zeolites
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DOI：
10.1016/j.apcata.2003.07.014
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发表时间：
2004-01
影响因子：
5.5
通讯作者：
Kuo-Ching Wu;Yu‐Wen Chen
中科院分区：
文献类型：
--
作者：
Kuo-Ching Wu;Yu‐Wen Chen
大多数用于乙酸乙酯（EAc）生产的商业方法是经由液相酯化。由于热力学的限制，乙酸乙酯的总收率被限制在67%与等摩尔的反应物进料的乙酸和乙醇。反应在363- 400 K下进行，乙醇/乙酸的摩尔比=1.5，LHSV=1h−1。在这种新的EAc合成方法中的关键参数之一是反应（酯化）温度。它被保持在液相和气相操作状态之间，在该操作状态下，反应组合物的一些部分被蒸发。主要的考虑是基于气相反应中的平衡常数，其高于液相中的平衡常数。在液相中的初始反应阶段具有反应器尺寸较小和与催化剂更有效接触的优点。由于在最终气相中已经达到平衡，由于平衡常数的限制，获得了较高的乙醇转化率。因此，液相体系的平衡转化率约束和气相反应的较大反应器体积要求都已被克服。在本研究中，单程乙醇转化率成功地从67mol%提高到85mol%。此外，在该新方法中使用的固体酸催化剂对环境的影响小，并且不会对反应器壁造成腐蚀。这些催化剂在2200 h内具有连续的性能。评估还表明，可以节省一半的工艺用水和三分之一的净化蒸汽消耗。
Most of the commercial processes for ethyl acetate (EAc) production are via liquid-phase esterification. Owing to the thermodynamic limitations, the overall yields of EAc are confined to 67% with equimolar reactant feeds of acetic acid and ethanol. The reactions were conducted at 363–400K, with molar ratio of ethanol/acetic acid=1.5 and with LHSV=1h−1. One of the critical parameters in this novel EAc synthesis process is the reaction (esterification) temperature. It was kept between the liquid- and gas-phase operation regimes at which some parts of the reacting composition were vaporized. The major consideration is based on the equilibrium constants in the gas-phase reaction, which are higher than those in the liquid phase. The initial reaction stage in the liquid phase has the advantage of smaller reactor size and more efficient contacting with the catalysts. As the equilibrium had been achieved in the final gas phase, a higher conversion of ethanol was obtained due to the equilibrium constant constraints. Consequently, both the equilibrium conversion constraint for the liquid-phase regime and the larger reactor volume requirement for the gas-phase reaction has been overcome. In this study, the one-pass ethanol conversion was successfully improved from 67 to 85mol%. In addition, the solid acid catalysts used in this novel process have low impact to the environment and cause no corrosion to the reactor wall. These catalysts had continued performance for 2200h. Evaluation also shows that half of the process water and one-third of the consumption of purification steam can be saved.