铜基催化剂上合成气甲醇合成的实用微动力学建模方法,Industrial & Engineering Chemistry Research

当前位置： X-MOL 学术 › Ind. Eng. Chem. Res. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

铜基催化剂上合成气甲醇合成的实用微动力学建模方法
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2019-05-13 , DOI: 10.1021/acs.iecr.9b01254
Jongmin Park ₁ , Jiyeong Cho ₁ , Yongkyu Lee ₁ , Myung-June Park , Won Bo Lee ₁

Affiliation

在这项研究中，描述了一种实用的策略，用于开发一种在铜基催化剂上由合成气合成甲醇的微动力学模型。全面的模型包括针对CO和CO ₂的28种可能的基本步骤反应的正向和反向反应氢化和水煤气变换反应。从头算密度泛函理论（DFT）和半经验单位键指数-二次指数（UBI-QEP）方法的组合用于确定吸附和活化能的热量。DFT计算证实了甲酸盐（HCOO **）以双齿形式吸附，并为随后的UBI-QEP计算提供了气体和表面中间体的焓和吸附能。从过渡态理论的数量级作为初始值并通过拟合实验数据来估计指数前因子，从而通过不计算平移，旋转和振动运动的振动频率和分配函数来减少计算负荷。对于反应堆模型，使用部分平衡比来降低微动力学模型的刚度。通过考虑相对较快的阶跃反应，提出了最合理的反应途径，而氢的表面反应通过速率控制程度，发现₃ CO *和H *是速率确定步骤。开发的模型还用于评估进料中的温度，压力和H ₂馏分对甲醇合成速率的影响，以阐明合适的操作条件。通过与其他报告的工作进行比较，验证了模型的有效性。可以进一步利用提出的方法来有效开发其他微动力学模型。

"点击查看英文标题和摘要"

Practical Microkinetic Modeling Approach for Methanol Synthesis from Syngas over a Cu-Based Catalyst

In this study, a practical strategy to develop a microkinetic model for methanol synthesis from syngas over a Cu-based catalyst is described. The comprehensive model consists of forward and backward reactions of 28 possible elementary-step reactions for CO and CO₂ hydrogenation and the water–gas shift reaction. A combination of ab initio density functional theory (DFT) and semiempirical unity bond index–quadratic exponential (UBI-QEP) methods was used to determine the heat of adsorption and activation energies. DFT calculations confirmed that formate (HCOO**) adsorbs in a bidentate fashion and provided the enthalpies and adsorption energies of gas and surface intermediates for subsequent UBI-QEP calculations. The pre-exponential factors were estimated from the order of magnitude of the transition state theory as the initial values and by fitting the experimental data, thus reducing the computational load by not calculating the vibrational frequencies and partition functions for translational, rotational, and vibrational motions. For the reactor model, partial equilibrium ratios were used to reduce the stiffness of the microkinetic model. The most plausible reaction pathways were suggested by considering relatively fast step reactions, while the surface reaction of H₃CO* and H* was found to be the rate-determining step by the degree of rate control. The developed model was also used to evaluate the effects of the temperature, pressure, and H₂ fraction in the feed on the methanol synthesis rate to elucidate the suitable operating conditions. The model effectiveness was validated by comparison with other reported works. The proposed approach can be further exploited for the efficient development of other microkinetic models.

更新日期：2019-05-16

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南