Alternative multiphase reactors for fine chemicals: A world beyond stirred tanks?

Novel supported Pd hydrogenation bionanocatalyst for hybrid homogeneous/heterogeneous catalysis

The purpose of this article is to report the development and application of a novel MRI (magnetic resonance imaging) technique which provides 2-D images of in-plane resolution 391x781 μm 2 , with a data acquisition time of 160 ms. In this article, the capabilities of this technique are illustrated with application to gas-liquid flow (more commonly referred to as Taylor flow or bubble-train flow) through a ceramic square-channel monolith system, for which it is demonstrated that bubble-size distributions, phase volume fractions, and bubble-velocity distribution can be obtained.

Dynamic MRI visualization of two‐phase flow in a ceramic monolith

Three-phase photocatalysis using suspended titania and titania supported on a reticulated foam monolith for water purification

The photocatalytic degradation of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, a non-biodegradable nitrogenous organic compound) in water was optimised under UV radiation using titanium dioxide photocatalyst. The reactor used was a pilot scale cocurrent downflow contactor photocatalytic reactor (CDCPR), a system offering very high mass transfer efficiency. The effect of photocatalyst loading, initial substrate concentration, temperature, pH, and different combinations of UV, O 2 , H 2 O 2 and TiO 2 on the photocatalytic oxidation of DBU was investigated. The TiO 2 photocatalyst used was Degussa VP Aeroperl P25/20, a granulated form of Degussa P-25, recently developed to ameliorate downstream catalyst separation problems. The CDCPR was fitted with an internally and vertically mounted 1.0 kW UV lamp. The reactions were carried out at 40–60 °C and 1 barg, with the reactor being operated in closed loop recycle mode and suspended photocatalyst being re-circulated. Optimisation of reaction conditions using a combination of TiO 2 , UV radiation and O 2 gave the most rapid degradation and mineralisation of the DBU in comparison with other processes. Under optimised conditions, 100% degradation of DBU was achieved in 45 min, with a quantum yield of 7.39, using a 1 kW lamp, 0.5 g/dm 3 TiO 2 , 100 mg/dm 3 DBU, 1 barg, 50 °C and pH of 3.17. Investigating the reaction pathway and its modelling showed a first order dependency, incorporating the effect of first intermediates of degradation. The activation energy was found to be 54.68 kJ mol −1 showing a significant influence of temperature on the photocatalytic degradation of DBU.

Optimisation of degradation conditions of 1,8-diazabicyclo[5.4.0]undec-7-ene in water and reaction kinetics analysis using a cocurrent downflow contactor photocatalytic reactor

The cocurrent downflow contactor (CDC) reactor-chemically enhanced mass transfer & reaction studies for slurry & fixed bed catalytic hydrogenation

A C.D.C. device has been developed which gives high gas-liquid mass transfer coefficients (k L a) in small operating volume short contact times via high interfacial area (1000-1500 m 2 /m 3 ) and gas hold up (E g =0.5-0.6). This has been employed to advantage in facile catalytic hydrogenation reactions when, with the C.D.C. as a slurry reactor it is possible to largely overcome hydrogenation mass transfer resistance, thus enabling the full activity catalyst to be employed. Preliminary studies have indicated that a similar performance may be obtained using certain packings which will eliminate a catalyst separation problem

X. X. Lu

Papers

The cocurrent downflow contactor (CDC) reactor-chemically enhanced mass transfer & reaction studies for slurry & fixed bed catalytic hydrogenation

The cocurrent downflow contactor (C.D.C.) : mass transfer and reaction characteristics in unpacked and packed-bed operation