This project involves the development of conventional and microwave powered acid digestion processes which successfully remove catalysts and their supports from the nanotube products.
The CNT products synthesised using the fluidised-bed CVD technique are typically a mixture of carbon, metal catalysts, catalyst support materials and reaction by-products, e.g. amorphous carbon. In particular, the catalyst supports occupy approximately 85wt%, or more, of the as-synthesised CNT products.For the development of commercially viable nanotube products, high purity CNTs are required, and if manufactured in large quantities via fluidised-bed CCVD, purification is therefore an indispensable step to remove impurities before use. Micron-sized granular materials, i.e. alumina, silica and zeolite, are often used as catalyst supports due to their inert properties at high temperatures.The methods reported in the literature for the purification of catalyst supports either use hydrofluoric acid (HF), which because of its inherent toxicity poses severe challenges in designing a large-scale CNT purification process, or take several hours to dissolve the catalyst supports and metal catalysts, thereby requiring large plant, and hence increased cost, to accommodate the long residence times required.No effective methods of achieving high CNT purity have been reported for the purification of the CNT products synthesised in a fluidised bed by CVD on micron-sized catalyst supports. We are developing conventional and microwave powered acid digestion processes which successfully remove catalysts and their supports from the nanotube products.
The opportunity ID for this research opportunity is 347