The purpose of this work is to investigate the effect that a solvent mixture has on the process-wide performance of the hydroformylation of 1-dodecene. A thermomorphic solvent mixture consisting of dimethylformamide and decane is used as a tunable solvent that ensures monophasic conditions during the reaction and that is also used to separate the homogeneous catalyst from the product through temperature controlled phase splitting in a decantation unit. So far reactor and process design for this reaction has been primarily based on a specific composition of the solvent mixture and without considering the economic impact of catalyst leaching. In order to reduce the complexity of the conceptual process design problem, linear regression models were used to accurately estimate the partition coefficients of the multicomponent mixture in the decanter. Using limited available experimental data from the literature, correlations were derived for catalyst loss based on the composition of the thermomorphic solvent system. Optimization results show that the catalyst loss has a significant effect on the total annualized cost of the process and that the frequently studied solvent composition should be altered to increase catalyst retention.
■ INTRODUCTIONIn the past decade, interest in homogeneous catalysis has increased substantially with the recovery or retention of expensive transition metal catalysts being the object of much study. This is especially true in the hydroformylation of longchain olefins where, due to the high cost of the catalyst complex composed quite often of rhodium and expensive ligands, industrial realization has been problematic. 1 Many different methods have been investigated primarily for the hydroformylation of 1-octene, which is extensively discussed in the review by Cole-Hamilton. 2 One effective method for hydroformylation has been done using supported ionic liquid phase catalysis, where the catalyst is supported in a thin film formed by an ionic liquid. 3 Other attempts at restricting catalyst loss involve tethering the catalyst complex to mesoporous materials, effectively creating semiheterogeneous catalysts. 4 Membrane filtration methods were also effectively developed for the continuous hydroformylation of 1-octene using specially designed polymer catalysts, whose bulky nature reduces the permeability of the catalyst through the membrane. 5 A CO 2 -expanded liquid (CXL) enhanced version of this process has also been implemented and operated economically with reasonably low and stable levels of catalyst loss. 6 A similar principle has been investigated using molecular weight enhanced ligands with polyhedral oligomeric silsesquioxanes (POSS) to increase retention in nanofilters. 7 Various hydrogenation reactions also utilizing a rhodium-based homogeneous catalyst in aqueous micellar solutions were investigated for catalyst performance and recovery. 8 Similar procedures have been used to recover the rhodium-based catalyst complex in the hydroformylation of 1-dodecene by using surfactants 9,10 or by...