Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

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• 作者：Nikolai E. Musko ; Anker Degn Jensen ; Alfons Baiker ; Georgios M. Kontogeorgis ; Jan-Dierk Grunwaldt
• 关键词：CO2&ndash ; 2-butenal VLE ; Supercritical CO2 ; Selective hydrogenation ; Equations of state ; CPA
• 刊名：Applied Catalysis A: General
• 出版年：2012
• 出版时间：7 November, 2012
• 年：2012
• 卷：443-444
• 期：Complete
• 页码：67-75
• 全文大小：674 K

文摘

Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were performed using a 5 wt % Pd on activated carbon in custom-designed high pressure autoclaves at 323 K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental vapour-liquid or liquid-liquid equilibria data available in the literature. No experimental data for the CO₂-2-butenal binary system were available in the literature; therefore, the bubble points of this mixture of varying composition at three different temperatures were measured in a high-pressure view cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO₂ the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved in the so-called ¡°expanded liquid¡± region, which is located near the critical point of the reacting mixture. It was also found that in this point the hydrogen concentration achieved its maximum in the CO₂-expanded phase. Furthermore, the pressure - temperature regions where the multicomponent reaction system exists in one single phase and in multiphase were calculated.