Catalyst cartridge system

Consequently a cartridge system for the hydroformylation of a variety of different alkenes using a single batch of catalyst was developed to fully exploit the potential of this approach (Scheme 1). Four different alkenes were applied in total using the same batch of catalyst for nine consecutive catalytic cycles. Conversion was driven to completeness in all cases, with selectivities remaining unchanged. Only 1.2% of rhodium and 2.4% of phosphorus was lost in nine cycles. Representative results are shown in Table 1. 

The Csajagi research group used a commercial X-Cube continuous flow reactor system [32] to perform similar reactions. The reactor is made of stainless steel, capable of reaching pressures of up to 150 bar, and equipped with preloaded catalyst cartridges. Monoamides of aryldicarboxylic acids are obtained in a reaction over a tetrakis(triphenylphosphine)palladium catalyst using A-methylpyrrolidone as base [33]. Terephtalic acid was reported as the byproduct, but not the oc-ketoamide. 

Metal-catalyzed cross-couplings are key transformations for carbon-carbon bond formation. The applicability of continuous-flow systems to this important reaction type has been shown by a Heck reaction carried out in a stainless steel microreactor system (Snyder et al. 2005). A solution of phenyliodide 5 and ethyl acrylate 6 was passed through a solid-phase cartridge reactor loaded with 10% palladium on charcoal (Scheme 2). The process was conducted with a residence time of 30 min at 130°C, giving the desired ethyl cinnamate 7 in 95% isolated yield. The batch process resulted in 100% conversion after 30 min at 140°C using a preconditioned catalyst. 

Most recently, a catalyst system based on PEG-modified phosphine ligands was reported to allow for a highly effective C02-induced separation procedure. In this case, the scC02 was used only at the separation stage to precipitate the catalyst and extract the products. The hydrogenation of styrene to ethyl benzene was used as a benchmark reaction, and it was shown that the catalytic active species could be recovered and not only re-used for another hydrogenation but also be subjected as a cartridge to a series of different transformations [43]. 

Several limitations hamper the development of efficient systems for cartridge catalysts based on the more conventional regulated systems (1) Thermal and/ or chemical stress can lead to deactivation of the organometallic catalyst (2) Additives used to induce precipitation may accumulate in the catalyst... 

Scheme 3.15 Hydroformylation as a benchmark reaction to validate the cartridge catalyst system MeOPEG750-PPh2/[Rh(acac)(CO)2]/scCO2 (Reproduced from Ref. [76], with the permission of John Wiley and Sons)...

The samples were pre-calcinated at 550°C (6 h) with a heating rate of l°C.min-l in a quartz cell in a flow (200 ml.min-l) of dry N2-O2 mixture. After cooling to 100°C, the zeolite was saturated during 6 h with a dry CO2 stream (12 ml.min-1) at atmospheric pressure. A flow of dry N2 (9.8 ml.min l) filtered on a cartridge (% H2O<0.4 ppm) was then admitted. After temperature equilibration of the system, the zeolite sample was heated at a rate of 3°C /min, in steps of 50°C. At each step temperature, the catalyst was maintained during 2 h. llie desorbed CO2 was collected under a nitrogen flow in a NaOH solution thermostatized at 25°C. The amounts of evolved CO2 were determined by titration continously performed by conductimetry using a conductivity cell (Schott LF 3100 Pt, K=1.0), connected to a Consort K 320 conductimeter. 

Researchers further optimized purification of a model ATRP reaction using the same automated parallel synthesizer that was outfitted with a solid-phase extraction (SPE) unit that utilizes silica gel or aluminum oxide filtration cartridges that can interface with synthesizer s liquid-dispensing system. The polymerization of MMA with p-toluenesulfonyl chloride (TsCl) as the initiator and CuCl/4,4 -dinonyl 2,2 -bipyridine (dNbpy) as the catalyst was chosen as a model reaction for this study. The PMMA pol5mier of this reaction was determined to have an MW of 12 000 Da and a PDI of 1.15. Sixty-four different purification conditions were analyzed by vaiying column materials, column lengths, and eluent collected. For the model reaction, a 1.5-cm-long artivated neutral or basic aluminum oxide column with 2 ml of THF eluent was optimal. 

The gas flows vertically through rectangular beds with minimum depth. The catalyst beds and an interchanger are installed on a cartridge that can be inserted into the vessel by a trolley system, rolling on tracks [151. 

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