Continuous-flow reactor supercritical

Supercritical fluids allow the formation of species that cannot be made in conventional solvents. For example, rj2-H2 complexes have been generated by direct reaction of hydrogen with a transition metal carbonyl complex [10]. In order to isolate these compounds, a continuous flow reactor was used and such compounds could be isolated with surprising ease. 

Mesitylene was alkylated with propylene or 2-propanol in supercritical CO2 using Deloxane, a polysiloxane-supported solid acid catalyst in a continuous flow reactor.406 Monoisopropylation with 100% selectivity occurred with 2-propanol. 

Initial studies of phenol SCWO Involved in extensive SCWO study Investigated the unique features of supercritical water in terms of density, dielectric constant, viscosity, diffusivity, electric conductance, and solvating ability Treatment of hazardous organic compounds Application of SCWO to the decomposition of sludges Found that sludge readily decomposes at near-critical water conditions with 02 or H202 as an oxidant in a batch or continuous flow reactor Treatment of sludges... 

Figure 8 A continuous flow reactor system for subcritical and supercritical studies. (From SRI International.)...

Selective hardening of edible oils in discontinuous stirred tank reactors (STR), continuous trickle bed reactors and in continuous flow reactors operating with supercritical CO2... 

The combination of ionic liquids with supercritical carbon dioxide is an attractive approach, as these solvents present complementary properties (volatility, polarity scale.). Compressed CO2 dissolves quite well in ionic liquid, but ionic liquids do not dissolve in CO2. It decreases the viscosity of ionic liquids, thus facilitating mass transfer during catalysis. The separation of the products in solvent-free form can be effective and the CO2 can be recycled by recompressing it back into the reactor. Continuous flow catalytic systems based on the combination of these two solvents have been reported [19]. This concept is developed in more detail in Section 5.4. 

The promising results obtained under batch-wise operation could be confirmed also under continuous-flow conditions. As schematically shown in Fig. 2, the substrate was injected with an HPLC pump into a stream of premixed CO2 and O2 before entering the reactor. The supercritical mixture was bubbled through the stationary PEG phase containing the Pd nanoparticles. 

Heterogeneously catalyzed hydrogenation reactions can be run in batch, semibatch, or continous reactors. Our catalytic studies, which were carried out in liquid, near-critical, or supercritical C02 and/or propane mixtures, were run continuously in oil-heated (200 °C, 20.0 MPa) or electrically heated flow reactors (400 °C, 40.0 MPa) using supported precious-metal fixed-bed catalysts. The laboratory-scale apparatus for catalytic reactions in supercritical fluids is shown in Figure 14.2. This laboratory-scale apparatus can perform in situ countercurrent extraction prior to the hydrogenation step in order to purify the raw materials employed in our experiments. Typically, the following reaction conditions were used in our supercritical fluid hydrogenation experiments catalyst volume, 2-30 mL total pressure, 2.5-20.0 MPa reactor temperature, 40-190 °C carbon dioxide flow, 50-200 L/h ... 

Suzuki-Miyaura coupling has also been conducted in a capillary reactor (400 i.m inner diameter).A commercial-scale continuous flow system consisting of a 14.5 cm x 25.4 mm column packed with Pd catalyst has also been developed. In this case, supercritical carbon dioxide is used as... 

These alternative reactor technologies can be combined with Green Chemistry methods including, for example, catalytic membrane reactions and continuous flow supercritical fluid reactions. 

After adjusting the pressure again for possible loss CO2 if necessary, the reactor is charged again with a new aqueous substrate phase for repeated use of the catalyst phase. Obviously, the system is readily applicable to continuous-flow processing using countercurrent flow techniques as established in liquid/supercritical extraction processes [40]. 

Table 15. Influence of Supercritical Phase Density on the Alkylation Performance of a K2.6H0.4PW Catalyst in a Continuous Flow Fixed Bed Reactor (Isobutane/Butenes Molar Ratio of 20, Temperature of 145°C)...

---