The Commonwealth Scientific and Industrial Research Organization (CSIRO), with its long and storied history in chemical innovations, has developed significant capability in flow chemistry as a key driver of process intensification and has recently launched “FloWorks”, a centre for industrial flow chemistry in Clayton, Victoria – a purpose-built 410 m² pilot scale facility.

The collaborative technology platform will be a foundry available for industry and research bodies to partner and develop flow chemistry processes. It offers a range of engagement models from early discovery stages to pilot scale and technology transfer (fig. 1).

Polymers

Flow reactors from laboratory scale (a few grams) to pilot plant scale are available and given CSIRO’s capabilities in polymer chemistry and science, a range of polymerization methods and flow chemistry technologies are offered.

Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization technology is an established form of controlled free radical polymerization which allows the rational design of well-defined polymeric structures. It can be used in a wide range of monomers and reaction conditions and provides access to polymers with unprecedented control over size, composition and architecture. RAFT can be used for solution, emulsion and suspension polymerizations, in batch, as well as flow chemistry.

Anionic polymerization is another form of controlled addition polymerization of vinyl monomers, providing access to polymers
with predicted molecular weights, narrow molecular weight
distributions, and defined end-groups. The ability to perform anionic polymerization using continuous processing methods (Flow Chemistry) removes the problem of batch-to-batch reproducibility encountered using batch processing.

Condensation polymerization is a step-growth polymerization process that can be used with non-vinylic monomers. CSIRO has used this technology to design and synthesize biostable and biodegradable polymers.

Catalysis

CSIRO combines expertise in early stage discovery and development of catalytic processes, incorporating new manufacturing technologies such as 3D metal printing and metal cold spraying. Early stage discovery can include catalyst high throughput screening at CSIRO’s automated high-throughput facility and chemical process development of the synthetic route at bench scale. The transfer to commercialization involves process scale-up to pilot or pre-commercial scale using intensified continuous flow processes, techno-economic analysis and the final technology transfer to the commercial partner for chemical production.

CSIRO’s research in continuous flow solutions for chemical catalysis includes a series of cutting-edge capabilities, which are described below.

Catalytic Static Mixers (CSMs): The current methods for heterogeneous catalysis using packed bed reactors pose many limitations. Fluid flow through the bed, as well as temperature and concentration gradients, can often be highly non-uniform, making heat control difficult – especially on large scale. For liquid phase applications, pressure drop along the bed can also be highly problematic. The size and shape of catalyst particles determine the performance of the catalytic reaction and the physical processes occurring inside the reactor – such as fluid flow, mixing as well as heat and mass transfer – often lead to undesirable limitations. A different approach is needed. Working with additive manufacturing experts, researchers at FloWorks are developing a hierarchical catalytic reactor approach. This new method involves a tailored, 3D printed mixing solution married with a range of active catalyst coatings for different catalytic reactions. The tubular design of the continuous flow reactor provides superior process control when compared with packed bed columns or stirred batch vessels. The metal mixer scaffolds can be designed and manufactured to the fluidic application, before the catalyst is directly deposited via electroplating, cold spraying, or other deposition methods. The Catalytic Static Mixers (CSMs) can be readily inserted into reactor tubes, allowing for easy changeover of catalyst. This makes the CSM technology a versatile and efficient tool for R&D and chemical production.

As hydrogenation is one of the most common reactions used in the chemical manufacturing industry, the CSM reactor concept has been developed for a series of metal-catalysed gas-liquid hydrogenations and transfer hydrogenations in continuous flow. High turn-over-frequencies and space-time-yields were achieved with very low leaching of the metal catalyst. The technology can be adapted to a number of different manufacturing sectors including: pharmaceuticals, fine chemicals, food products / supplements, polymers and agrochemicals.

Homogeneous Catalysis using Tube-in-Tube Flow Reactors: Researchers at CSIRO in collaboration with the University of Cambridge and the University of Melbourne have developed a new tube-in-tube flow chemistry reactor system for a range of gas-liquid phase catalytic applications. The tubular membrane system allows both heterogeneous and homogeneous catalytic reactions to be carried out at elevated pressures in a continuous flow mode, leading to improved inherent safety of these processes.

The use of a gas-permeable fluoropolymer, Teflon AF-2400, is a simple method of achieving efficient gas–liquid contact to afford homogeneous solutions of reactive gases in flow.

The membrane permits the transport of a wide range of gases, including H₂, O₂, O₃, CO, NH₃ and others, allowing for key C–C, C–O, and C–N bond forming and hydrogenation reactions.

Advanced Porous Materials

Hyper-porous materials – including metal-organic frameworks (MOFs) and their metal-free counterparts, covalent organic frameworks (COFs) – have attracted much attention in recent years owing to their vast potential for application to areas such as energy and gas storage, separation science and catalysis. The availability of scalable synthesis methods is a significant challenge for the translation of MOFs and COFs into industry. Over the last decade, CSIRO has met this challenge through the development of scalable continuous flow methods for the synthesis and manufacture of these materials.

For example a continuous flow MOF production process that is scalable to multi-kilogram per day production has been developed (fig. 2). The process is efficient delivering a range of MOFs with surface areas that consistently match those reported from laboratory scale synthesis and high space time yields. The use of propriety downstream processing ultimately produces MOFs in a variety of palletised formats and geometries.

Covalent organic frameworks (COFs) are three-dimensional organic porous and crystalline polymers with extended structures in which building blocks are linked by strong covalent bonds. COFs are comprised entirely from light elements (H, B, C, N, and O) and can therefore be considered the organic analogues of MOFs. A unique feature of COFs is that the physical properties of the framework can be tailored via judicious choice of the geometry, dimensions and functionality of the organic building blocks. COFs are known to exhibit unique photo-physical properties [that] can be employed as platforms for catalysis and have recently emerged as attractive materials for application in gas adsorption and separation science.

CSIRO also has developed scalable continuous flow methods for the synthesis of carbon-based molecular cages. Covalent organic cages are a subset of COFs that are discrete molecules rather than extended solids. These novel porous materials can be solution processed which is a significant advantage over their solid-state counterparts.

The manufacturing platform will pave the way for the industrial uptake of this new class of carbon-based hyper-porous materials.

Summary

Through the right people, networks, equipment and facilities FloWorks has developed sustainable and financially viable flow chemistry technologies for its partners and has deployed new processes into the Australian chemical industry.

The Commonwealth Scientific and Industrial Research Organization (CSIRO) is a Statutory Authority of the Australian Government and was founded in 1916, mandate to assist the Australian industry and fulfil the national and international obligations of the Commonwealth. The Australian chemical industry is a critical enabling industry in Australia, feeding into almost every other industry sector. In recent years, the chemical community in Australia has come together and put forward two important roadmaps. In the first, the Australian Academy of Science has detailed a Decadal Plan for Chemistry, while at the other end of the spectrum Chemistry Australia has put forward a road map for the chemical industry. Collectively these documents identify continual innovation and sustainability as key drivers for the industry going forward.