Clean energy and sustainability –Recycling and clean processing
Lead free PZT transducers
Processing of lead-free piezoelectric ceramics based on the system sodium potassium niobate. These are candidate materials which when suitably developed should enable piezoelectric ceramics based on lead zirconate titanate (PZT) to be replaced. PZT ceramics are widely used in transducers, actuators and medical imaging applications. I guess this comes under the 'Sustainability' heading and by replacing lead-free materials they are 'Clean' technology.
Production of materials via low CO2 processes
The metals industry contributes about 20% of the world’s production of carbon dioxide. We have been examining a process whereby the oxide is made the cathode in the bath of the halide and an electropositive element. On the passage of current the oxygen in the oxide ionises, dissolves in the salt, and diffuses to the anode where it discharges. By using an inert anode and electricity from renewable sources, the process does not emit any carbon dioxide.
A joint project with Earth Sciences for investigating the carbon seqestration activity in nature over geological times. Other projects dealing with carbon dioxide absorption and utilization are also being explored.
Environmental catalysis. (in collaboration with the University of Cadiz)
CePrOx mixed oxides, which present improved redox properties compared with those characteristic of pure ceria (CeO2), have a wide range of potential applications, spanning from environmental catalysis to nontoxic pigments for industrial ceramics, or as cathodes for fuel cells. Within the field of environmental catalysis they have been tested as alternative redox promoters in processes such as three way catalysis (TWC), in low temperature water gas shift (WGS) for hydrogen production, as well as in the catalytic wet air oxidation (CWAO) reaction to abate organic pollutant components present in industrial wastewaters. In all these applications, both the thermodynamics and the kinetics of the exchange of the oxide lattice oxygen with its environment, which are usually quantified in terms of the so-called oxygen storage capacity (OSC), are critical parameters. An in-depth structural and analytical investigation of two CePrOxmixed oxide catalysts is being undertaken aimed at clarifying the origin of the differences in the evolution of their oxygen storage capacity with temperature. Using a combination of transmission and scanning transmission electron microscopy techniques, the fine details of the structural and compositional changes of the two catalysts with reduction temperature has allowed us to establish the role of SiO2 as a stabilizer of the oxygen handling properties of the Ce-Pr mixed oxide phase under high temperature reducing environments.
Carbon dioxide sequestration (in collaboration with Chemical Engineering) This is an ongoing project with Dr John Dennis and his group (Chemical Engineering) to investigate the structure of calcium oxide before and after CO2 sequestration to determine the efficiency of the porous oxide and the structure and distribution of the carbonate after CO2 sequestration cycles.
Improved CO Oxidation Activity for Purification (in collaboration with the University of South Carolina )
The CO oxidation in the absence and presence of H2 has attracted significant attention recently because of its potential application in indoor/cabin air cleanup and in the purification of hydrogen streams used in proton exchange membrane (PEM) fuel cells. Hydrogen is currently produced by catalytic steam reforming, partial oxidation, and auto-thermal reforming of hydrocarbons. However, CO is formed as a byproduct in all of these processes and must be subsequently removed prior to the introduction of hydrogen to PEM fuel cells, due to the high sensitivity of the Pt-based PEM electrocatalysts to poisoning by CO. The preferential oxidation (PROX) of CO in the presence of hydrogen is currently used commercially for this application due to its efficiency and relative simplicity. Supported metal catalysts incorporating Pt and other noble metals have been extensively investigated for PROX and have exhibited substantial activity for this reaction. Correlations were made between the nanoscale structures revealed by electron microscopy and tomography and the improved catalytic performance.
High-performance nanocatalysts for single-step hydrogenations – using bio-feedstocks to manufacture plastics (in collaboration with J.M. Thomas and others)
With the impending arrival of the so-called hydrogen economy and the parallel, universal drive toward clean technology, there is a pressing need for the discovery and development of single-step (and preferably solvent-free) highly active and highly selective catalysts for the hydrogenation of a growing range of key organic compounds. In the future, with the decline of chemical feedstocks from fossil fuels, and the concomitant growth of those extracted from readily sustainable plant sources, the fraction of organic molecular products that are manufactured industrially by direct hydrogenation is inevitably destined to rise. Efficient, high-performance new catalysts, operating under mild and environmentally benign conditions, are therefore an exigent need. Electron microscopy and electron tomography is used to correlate catalytic activity and selectivity with the nanoscale structures.
Solid state Refrigeration
Development of electrocalorific materials for cooling applications.
K.G. Sandeman (now at Imperial)
Low energy production of tough fibres
The direct spinning of carbon nanotube fibres to provide the next generation of tough fibres as a basis for lightweight composites for transport and aerospace. The process, while showing the ability to make fibres with properties which compete with and even exceed those available today, is also intrinsically green in that the hydrocarbon carbon feedstock is converted into high tech carbon and hydrogen, which can then be burnt as the main source of heating for the reactor.