Smart nanostructures to make chemical reactors more energy efficient

Materials World magazine
,
1 Jan 2009

Nanostructured materials, tailored to respond to various stimuli, may form the basis of more energy efficient chemical reactors by regulating reactions, momentum, and heat and mass transfer inside the plants.

Smart structures, engineered from molecular metal oxides and polymers, could coat the reactor walls or be dispersed in fluids, and control reactions by varying their size, shape or microstructure in response to changes in the pH and temperature of the reactants, or through the application of light. This, in turn, changes the nanostructures’ heat and mass transfer properties. Applying this technology would enable the chemical, pharmaceutical and agrochemical industries to reduce energy usage and, in turn, their environmental impact.

Existing regulation systems rely on external conventional tools for measuring temperature, pressure and pH, with the inputs adjusted accordingly, requiring manpower.

A consortium of three UK universities, Leeds, Bath and Glasgow, is in the early stages of developing this nanotechnology over a three-year programme, funded by the UK’s Engineering and Physical Sciences Research Council.

Professor Lee Cronin of Glasgow University hopes the research programme will develop a library of multifunctional candidate materials through self-assembly of molecular precursors. ‘You could build a material that is a catalyst, a heat transfer agent and that can also take part in electronic transitions. This is quite an interesting goal in materials science.’

Cronin explains how a nanomaterial being used for its catalytic activity might respond. ‘If, as more heat is produced in the reactor, the microstructure of the cluster changed to remove that heat, you would then effectively have a self-regulating reaction. So you would prevent runaway and have feedback within the catalyst.’

The biggest challenge going forward is ‘making industrial scale quantities of the material with well defined properties’, notes Professor Yulong Ding of Leeds University. Key factors to be considered will be cost, safety and reliability.

Professor Hugo de Lasa of the Department of Chemical and Biochemical Engineering at the University of Western Ontario, London, Canada, is enthusiastic about the potential of the technology. ‘This is where the chemical processes should go in the future. Nanostructures as materials or catalysts in chemical reactors are very important because they bring the chemistry to the molecular scale.’

He acknowledges, however, that there are specific issues to overcome in handling nanoparticles and separating them from the reaction products. De Lasa notes, ‘There are big challenges, because these nanomaterials are subject to interparticle forces, and it is quite complex to disperse them directly in a chemical reactor’.