Development of a packed bed reactor for carbon nanotube synthesis

Abstract: Carbon nanotubes (CNTs) are one of the most attractive materials of the future that can be used in a range of applications from structural buildings to use in super-conductors. Commonly used materials such as copper, aluminium and steel are outperformed by CNT's mechanical, electrical and thermal properties on the nanoscale relative to their density. However, there are problems and issues that come from manufacturing nanomaterials on an industrial scale. The properties that are found on the nanoscale do not translate to the macro scale and their synthesis is very energy intensive. Further, there are issues surrounding current synthesis techniques which are used in academia and on small laboratory scales in industry. Floating catalyst chemical vapour deposition (FC-CVD) is one of the most promising routes for industrial scale-up however, there are issues concerning the reactor density and the carbon conversion. Both require an improvement in order for the process to become feasible.

This proposal will address the issue of understanding the concentration of all species at which aerogel forms. The methods to analyse the distribution of nanoparticles within the reactor both axially and radially will be performed via aerosol collection techniques. Once the fundamental reaction kinetics and concentrations of the chemically relevant species are both known and understood, the reaction will be put into a higher reaction density reactor. The data from this study will be used for modelling aerosol dynamics within the reactor and coupled with computational fluid dynamics model.

Further, this proposal will outline the design and creation of a pseudo packed bed reactor in which the catalyst precursors are delivered to the point at which the carbon has broken down into subsequent radicals. The reactor design and build including all materials used, will focus closely on providing a solution to the mass production of high quality carbon nanotubes.

Aerosol science has a significant impact on a broad range of disciplines, extending from inhaled drug delivery, to combustion science and its health impacts, aerosol assisted routes to materials, climate change, and the delivery of agricultural and consumer products. Estimates of the global aerosol market size suggest it will reach $84 billion/year by 2024 with products in the personal care, household, automotive, food, paints and medical sectors. Air pollution leads to an estimated 30-40,000 premature deaths each year in the UK, and aerosols transmit human and animal infections. More than 12 million people in the UK live with lung disease such as asthma, and the NHS spends ~£5 billion/year on respiratory therapies. Many of the technological, societal and health challenges central to these areas rely on core skills and knowledge of aerosol science. Despite this, an Industrial Workshop and online survey (held in preparation for this bid) highlighted the current doctoral skills gap in aerosol science in the UK. Participating industries reported that only 15% of their employees working with aerosol science at doctoral-level having received any formal training. A CDT in aerosol science, CAS, will fill this skills gap, impacting on all areas of science where core training in aerosol science is crucial.

Impact on the UK aerosol community: Aerosol scientists work across governmental policy, industrial research and innovation, and in academia. Despite the considerable overlap in training needs for researchers working in these diverse sectors, current doctoral training in aerosol science is fragmentary and ad hoc (e.g. the annual Fundamentals of Aerosol Science course delivered by the Aerosol Society). In addition, training occurs within the context of individual disciplines, reinforcing artificial subject boundaries. CAS will bring coherence to training in the core physical and engineering science of aerosols, catalysing new synergies in research, and providing a focal point for training a multidisciplinary community of researchers. Working with the Aerosol Society, we will establish a legacy by providing training resources for future researchers through an online training portal.

Impact on industry and public-sector partners: 45 organisations have indicated they will act as CAS partners with interests in respiratory therapies, public health, materials manufacturing, consumer and agricultural products, instrumentation, emissions and environment. Establishing CAS will deliver researchers with the necessary skills to ensure the UK establishes and sustains a scientific and technical lead in their sectors. Further, it will provide an ideal mechanism for delivering Continuing Professional Development for the existing workforce practitioners. The activity of CAS is aligned to the Industrial Strategy Challenge Fund (e.g. through developing new healthcare technologies and new materials) and the EPSRC Prosperity Outcomes of a productive, healthy (e.g. novel treatments for respiratory disease) and resilient (e.g. adaptations to climate change, air quality) nation, with both the skilled researchers and their science naturally translating to long-lasting impact. Additionally, rigorous training in responsible innovation and ethical standards will lead to aerosol researchers able to contribute to developing: regulatory standards for medicines; policy on air quality and climate geoengineering; and regulations on manufactured nano-materials.

Public engagement: CAS will provide a focal point for engaging the public on topics in aerosol science that affect our daily lives (consumer products, materials) through to our health (inhalation therapeutics, disease transmission and impacts of pollution) and the future of our planet (geoengineering). Supported by a rigorous doctoral level training in aerosol science, this next generation of researchers will be ideally positioned to lead debates on all of these societal and technological challenges.