Quick reactions

A microwave reactor could aid the swift production of drugs on an industrial scale

Pharmaceutical manufacturers could reduce their carbon footprint using new microwave technology that speeds up the chemical reactions necessary to produce active ingredients in drugs.

Microwave engineering specialists at UK research-and-development organisation C-Tech Innovation have created a prototype microwave reactor system capable of producing 20kg of pharmaceutical material in a span of 32 hours.

C-Tech recently received a development grant of £278,000 from UK environmental think-tank The Carbon Trust to scale up its system. The goal is to produce hundreds of kilograms or even tonnes of material every day for manufacturers of various chemistry-based products such as plastics and lubricants.

Microwaves have been used by laboratory chemists, particularly in pharmaceutical discovery, to speed up chemical reactions for years. Until now, microwave chemistry has not been used on an industrial scale because it has only been capable of producing milligrams to grams of material.

Darren Kell, leader of the microwave strategy group at C-Tech, said that the company’s microwave technology produces much more material because it uses a specially designed reactor capable of handling and reacting chemicals that constantly flow through it. Laboratory microwave reactors are designed to react chemicals only one batch at a time.

The challenge, he said, was finding the right design and materials for the reactor. ‘Using a glass reaction chamber at the very small scale is okay because, at that scale, it will withstand the pressure you’re applying to it. When you scale up, those problems become more acute and you need to start changing the design of components and selecting new materials that meet the pressure, temperature and chemical resistance.’

Kell could not reveal the C-Tech reactor’s material composition, but he did say that the material had to be dielectric so it could allow the passage of microwaves. ‘This precludes the use of metals, for instance, which would be the normal choice of engineering material for a chemical reaction,’ he said.

The use of a continuous-flow microwave reactor is considered to be a faster and more productive technique compared to chemical reactors currently used in industry. With those techniques, liquids are held in large tanks and kept at high temperatures for four to five hours. ‘We can condense that time down to a few minutes,’ said Kell, adding that chemical reactor tanks have to be held at a slightly higher temperature than desired to drive the heat into the reaction.

‘What that does is create a hot surface that is essentially hotter than your desired reaction temperature, which can cause problems in terms of undesired reactions and loss of yield,’ he added. ‘What microwaves allow you to do is not have that hot surface because it’s a volumetric heating method that heats the liquids directly.’

With the recent Carbon Trust grant, C-Tech will demonstrate how the benefits of speed and extra yield can also affect energy usage.

The Carbon Trust estimates that the UK chemical industry’s annual energy usage is currently around 68,000GWh, with a significant proportion of this being used in processes associated with the production of chemicals. C-Tech claims speeding up chemical reaction times on an industrial scale could result in energy savings of up to 90 per cent. The extra yield could also save energy by reducing the amount of reactant that needs to be processed.

Kell said there are no exact energy-saving figures to report yet from C-Tech’s prototype microwave reactor. The reactor, which churns out 20kg of material over 32 hours, is being used by Cambrex, a pharmaceutical company that produces its own compounds and manufacturers on behalf of other large multi-national drug companies. ‘We should be getting some more definite energy-saving figures out in six months’ time or so,’ he added.

Meanwhile, C-Tech is working to build another large reactor for Pentagon Chemicals, a UK-based chemical manufacturer of organic substances for use in life sciences and petrochemicals.

Kell said his team will work over the next 18 months, the scope of The Carbon Trust grant, to fully prove their technology’s energy-saving material.

‘By the end of it, we will hopefully have a larger-scale working reactor, which we can then use to demonstrate to potential customers,’ he added.