Scientists have developed a fully operational standalone solar-powered mini-reactor which offers the potential for the production of fine chemicals in remote locations on Earth, and possibly even on Mars.
The new system, which is capable of synthesising drugs and other chemicals in economically relevant volumes, ‘shines in isolated environments and allows for the decentralisation of the production of fine chemicals,’ according to Professor Noel. ‘The mini-plant is based on the concept of photochemistry, using sunlight to directly ‘power’ the chemical synthesis. We employ a photocatalyst, a chemical species that drives the synthesis when illuminated,’ Noel continues. ‘Normally powerful LEDs or other lighting equipment are used for the illumination, but we choose to use sunlight. For starters, this renders the synthesis fully sustainable. But it also enables stand-alone operation in remote locations. Our dream is to see our system used at a base on the Moon or on Mars, where self-sustaining systems are needed to provide energy, food and medicine. Our mini-plant could contribute to this in a fully autonomous, independent way.’
A solar-driven flow reactor
Development of the mini-plant started around five years ago when the Noel research group — at the time based at Eindhoven University of Technology -developed a ‘solar concentrator’. This is essentially a sheet of transparent plastic with micrometre-sized channels in which the chemical synthesis takes place. By adding dedicated dyes, the researchers developed the plastic into a solar guide and luminescent convertor. It captures sunlight and directs it towards the channels, while converting a substantial part of the light into red photons that drive the chemical conversion.
The next step was to turn the concentrator into a fully operational flow reactor. ‘This means we pump a reaction mixture of starting materials and photocatalyst through the sunlit channels,’ says Noel. ‘The desired chemical conversion takes places in these channels so that they are, in fact, our alternative to the traditional chemical synthesis flasks or vessels.’ Noel goes on to explain that even though the channels are quite tiny, such a ‘flow reactor’ can produce quite relevant outputs since it operates from sunrise to sunset in a continuous manner. ‘What’s more,’ he adds, ‘the use of channels allows for a far more effective coupling between light and chemistry than is possible when using traditional flask reactors.’
Maximum efficiency
The Noel research group had already demonstrated the solar flow reactor concept by synthesising a range of medicinally relevant molecules, albeit on a laboratory scale in a controlled environment. Now, in their recent paper in ChemSusChem, they describe how they developed a viable, optimally effective autonomous photosynthesis system and employed it in field tests. They also provide an outlook on aspects such as application potential and economic performance.
Story Source: Materials provided by Universiteit van Amsterdam. Note: Content may be edited for style and length.