Separation of metathesis catalysts and reaction products in flow reactors using organic solvent nanofiltration

Abstract

Organic solvent nanofiltration (OSN), a relatively new low energy separation technology, has been used to reduce metal contamination of ring closing metathesis reaction products. The catalysts used were readily available commercial Hoveyda-Grubbs and Umicore M series catalysts. These reactions were performed in a flow reactor with in-line membrane separation, and high catalyst retention can be achieved. In the flow reactor set up a beneficial effect on catalyst life-time on changing from solvents such as dichloromethane to environmentally more benign acetone, which reduces initiation rates, was demonstrated.

Volume intensified dilution of a ring‐closing metathesis in ethyl acetate by means of a membrane‐assisted process in solvent recycle

“…If the reaction was to be carried out within the filtration loop the RCM secondary product ethene, a catalyst poison, can only escape the system via permeation through the membrane and with the system under pressure more ethene will be dissolved in solution. The negative effect of ethene within the pressurized system has already been demonstrated …”

“…The performance of the membranes is characterized by their solute rejection and permeance. 24 The use of membranes in RCM reactions has already been reported in the literature [28][29][30][31][32][33][34][35][36] with the emphasis being placed upon separation of catalyst from reaction products of very small molecular mass and in general in post-reaction processing situations. In contrast the focus of this work is the in-line solvent recycling with the aim of reducing the solvent volumes required for the macrocyclization.…”

Coupling Rhodium‐Catalyzed Hydroformylation of 10‐Undecenitrile with Organic Solvent Nanofiltration: Toluene Solution versus Solvent‐Free Processes

“…Few studies have focused on the recycling of homogeneous metal catalysts by OSN in solvent‐free media (later referred to as bulk media) while some studies have dealt with the influence of the solvent on the membrane performances . Van der Gryp et al .…”

“…Many laboratory-scale studies have already established the potential of OSN for homogeneous catalyst recycling. [10][11][12][13][14][15][16][17] Upon tuning the type of membrane, [18][19][20][21][22] catalyst, [23,24] solvent [25][26][27][28][29] and operating conditions (mainly transmembrane pressure, TMP [27,30,31] and sometimes temperature [28,31,32] ), almost full catalyst rejections were obtained. Nevertheless, it must be underlined that these studies usually focused on the catalyst rejection by the membrane and paid no or very little attention to the target product extraction, which is however an absolute requirement for an industrial production process.…”

“…Few studies have focused on the recycling of homogeneous metal catalysts by OSN in solvent-free media (later referred to as bulk media) while some studies have dealt with the influence of the solvent on the membrane performances. [25][26][27][28][29] Van der Gryp et al studied a metathesis process coupling reaction and OSN performed in bulk. Using a Starmem 228 membrane (PI, MET-Evonik), 99 % of Ru catalyst rejection was achieved with a post-reaction mixture made of residual 1-octene (substrate), 7tetradecene (product) and 1-tetradecene (by-product).…”