• Urban, Andrew
• Hornung, Christian
• Tsanaktsidis, John
• Gunasegaram, Dayalan
• Nguyen, Xuan
• Hutt, Oliver
• Horne, Mike
• Mcgregor, Kathie

Abstract

Over the past decade flow chemistry using apparatus with micro- and millimetre sized channels became a disruptive technology for low volume, high value-add chemical manufacturing. These technological advances resulted from the growing demand for highly efficient chemical production in areas such as pharmaceutical and fine chemical manufacturing. Several different reactor devices have since been developed for solution phase, emulsion, liquid-gas, liquid-solid and triphasic processing. In comparison to their homogeneous liquid phase counterparts, reactors for liquid-solid heterogeneous catalytic applications are more complex and specialised, which meant that their implementation in organic synthesis has not been as widespread and straight forward. The catalytic solid phase needs to offer a large amount of active sites, which is often addressed by creating small pores; on the other hand the fluidic device needs to be designed such that the transport of starting materials and products in and out of the system is efficient and concentration and temperature profiles are homogeneous, which usually requires larger channels. In order to create a catalytically efficient yet practical reactor device, a functioning compromise between both is necessary.Our team at CSIRO has developed a new tubular reactor system for heterogeneous catalysis using a flexible, multifunctional immobilized catalyst platform. This immobilized catalyst is based on a 3D printed static mixer scaffold coated with catalytic layers. These catalytic layers can be deposited by a range of different techniques, including spray coating or dip coating and calcination; herein we have applied electroplating and metal cold spraying for the deposition of catalytic metal(0) layers such as Ni, Pd or Pt [1-3], two processes not commonly used for the preparation of catalysts. Tubular devices have a series of advantages over classical packed bed reactors or batch slurry reactors, such as high L/D ratios leading to excellent process control, well defined flow patterns and predictable and low pressure drop. A series of different hydrogenation reactions were conducted, reducing alkenes, alkynes, carbonyls, nitro- and diazo-compounds, nitriles, imines, and halides. These reductions are model systems for industrial applications in the pharmaceutical, fine chemistry, flavour and fragrances, food supplements or agrochemical sectors. For the reduction of alkynes, we managed to change selectivity of the CSM reactor by simply adjusting the reactor pressure in order to either yield an alkene or an alkane product. This demonstrates the versatility, efficiency and robustness of the CSM technology for heterogeneous catalytic reductions and its great potential for use in R&D laboratories and as a scale-up tool for chemical and pharmaceutical manufacturing.

Topics

• Deposition
• impedance spectroscopy
• pore
• compound
• alkane
• spray coating
• liquid phase
• dip coating
• alkyne
• alkene
• nitrile