Atmospheric microreactor system

Polymer-based microreactor systems [e.g., made of poly(dimethyl-siloxane) (PDMS)], with inner volumes in the nanoliter to microliter range (Hansen et al. 2006), are relatively inexpensive and easy to produce. Many solvents used for organic transformations are not compatible with the polymers that show limited mechanical stability and low thermal conductivity. Thus the application of these reactors is mostly restricted to aqueous chemistry at atmospheric pressure and temperatures for biochemical applications (Hansen et al. 2006 Wang et al. 2006 Duan et al. 2006). 

Both oxyhydrochlorinatlon of methane and chloromethane oligomerization studies were conducted in essentially the same microreactor system. All the reactants were introduced at pressures slightly above one atmosphere from gas cylinders, and flow rates were controlled by a Brooks four-channel mass-flow controller. The feed stream for the oxyhydrochlorinatlon reaction was sampled before and after an experimental run, while the product stream was continuously sampled on-line during the run to obtain a mass balance. A quadrupole mass spectrometer was used to analyze the feed and product... 

NSSTK and SSITK experiments were performed with an atmospheric flow system using either a tubular quartz microreactor (70 mg of catalyst) or a catalytic DRIFT cell from Spectratech, allowing the gases to flow through a fixed bed of catalyst pellets (about 30 mg) and able to be heated up to 1173 K. The gas composition was continuously monitored at the reactor outlet by online mass spectrometer and the surface composition was investigated by a FT-BR. spectrometer (Nicolet 550) with one spectrum recorded per second In all cases, the catalyst was pre-treated with He at 1013 K for 40 min. The reacting feed was composed of 10 vol.% methane ( CHj, CHj or CD4) and 90 vol.% He with a total flow rate of 24 ml/min. The reaction was carried out at 1 atm and 1013 K. Ar was used as an inert tracer. 

The aldol condensation/hydrogenation reaction was carried out in a continuous flow microreactor. The catalysts (0.5 g) were reduced in situ in a flow of H2 at atmospheric pressure at 723 K for 1 h for the palladium systems and 2 h for the nickel systems. The liquid reactant, acetone (Fisher Scientific HPLC grade >99.99%), was pumped via a Gilson HPLC 307 pump at 5 mL hr into the carrier gas stream of H2 (50 cm min ) (BOC high purity) where it entered a heated chamber and was volatilised. The carrier gas and reactant then entered the reactor containing the catalyst. The reactor was run at 6 bar pressure and at reaction temperatures between 373 and 673 K. Samples were collected in a cooled drop out tank and analyzed by a Thermoquest GC-MS fitted with a CP-Sil 5CB column... 

The systems 1% R11/AI2O3, 1% Pd/Al203 and 1% (Pd+Ru)/Al203 were also tested as catalysts for the NO reduction with H2, CO and propene as reductants, but different operating conditions were adopted. The reaction was conducted in a microreactor, at atmospheric pressure, temperatures from 75°C to 350°C and space velocity of 100 ml/min gcat- In a first series of tests, a large excess of reductant was used, the gas feed composition... 

For operation at atmospheric pressures the vacuum system is isolated from the microreactor using a slide valve. The slide valve contains an adjustable leak valve that controls the amount of reactor effluent that enters the vacuum system. The portion of the effluent that does not escape through the leak valve exits through an external vent that contains an adjustable pressure regulator. When the reactor is operated at atmospheric pressures the mass spectral data can be collected in a standard mass intensity versus mass number format. 

In this contribution, we present computer analyses of several selected temperature-programmed desorption (TPD) and temperature-programmed surface reaction (TPSR) experiments in a microreactor flow system operating under atmospheric pressure. The continuous stirred tank reactor (CSTR) and plug flow reactor (PFR) models have been applied for the design equation as... 

---