How Does the Critical Point Change during a Chemical Reaction in Supercritical Fluids? A Study of the Hydroformylation of Propene in Supercritical CO2

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• 作者：Jie Ke ; Buxing Han ; Michael W. George ; Haike Yan ; and Martyn Poliakoff
• 刊名：Journal of the American Chemical Society
• 出版年：2001
• 出版时间：April 25, 2001
• 年：2001
• 卷：123
• 期：16
• 页码：3661 - 3670
• 全文大小：174K
• 年卷期：v.123,no.16(April 25, 2001)
• ISSN：1520-5126

文摘

An understanding of homogeneous catalysis in supercritical fluids requires a knowledge of the phasebehavior and the variation in critical point as the reaction proceeds. In this paper, the critical temperatures, T_cand pressures, P_c, have been measured for a considerable number of mixtures representing the various stagesof the hydroformylation reaction of propene in supercritical CO₂ and different reactant concentrations. Criticalpoint data have also been measured for all of the binary mixtures of the components (CO₂, H₂, CO, propene,n- and isobutyraldehyde) which are not available from the literature or can be deduced from published data.We use the stoichiometry of the reacting system to simplify greatly the phase behavior problem by defininga path through the otherwise multidimensional "phase space". Satisfactory modeling of the data (0.3% in T_cand 3.0% in P_c) has been achieved using the Peng-Robinson equation of state and ignoring all binary interactionswhich do not involve CO₂. The model is used to explore the strategies needed to avoid phase separation incontinuous and batch reactions. At a given temperature, a batch reactor may need to be run under much higherpressures than a flow reactor if single-phase conditions are to be preserved throughout the course of the reaction.Most of the critical point data were measured acoustically, but a selection of points were validated using moretraditional view-cell procedures.