SPACE: Sustainable Production of Aerogels from Cellulose

Lead Research Organisation: University of Nottingham
Department Name: Div of Process and Environmental Eng


SPACE will develop the fundamental science required to underpin the development of continuous production processes for turning the most abundant natural material, cellulose, into high value nanostructured materials with well defined pore structures and pore functionality. It is based on my recent discovery that aerogels can be prepared by assembling cellulose nanowhiskers at low energy and without the use of toxic solvents or precursors. Cellulose nanowhiskers are monocrystalline rod-like nanoparticles made from plant material by a two-day multi-step acid hydrolysis batch process. Their self-assembly and surface modification is also performed in multi-step batch processes. SPACE will convert existing batch processes for nanoparticle production, surface modification and self-assembly into scalable continuous processes, through the development of a fundamental scientific understanding of different continuous nanomaterial processing techniques. This, in turn, will open up small and large scale production of multi-functional porous materials with a wide range of potential applications, including insulation, gas and liquid adsorption and separations, organic catalysis and sensing while increasing product quality, improving consistency, and greatly lowering the economic and environmental cost. The demonstrators will be designed to produce around 220 g of nanomaterials per hour (~5 kg per day).

Planned Impact

SPACE will develop a sustainable continuous nanomaterials production technology platform which is widely applicable to produce high-volume, high-efficiency nanomaterials to the benefit of our society. It is a multidisciplinary project with an inherent rich training environment, a great potential for outreach activities to promote the positive aspects of science and engineering, and industrially relevant deliverables that can be implemented directly and applied to a variety of different nanomaterials. This project will thus have a major impact and the PI has identified various pathways to maximise and exploit impact for society. Our project already has the support of three companies, two of which will make contributions to the development of our technology. One of these companies together with a third company are keen on commercialising materials we produce.


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Heath L (2013) Chitin nanowhisker aerogels. in ChemSusChem

Description The funding was sought to investigate the possibility of developing a continuous process for cellulose nanocrystals production and surface modification leading production of aerogels. Further we hoped to investigate the possibility of assembling the nanoparticles in a controlled manner to achieve structured products through surface modification. The project was to deliver within three Research Programmes (RPs) within the project. We have made significant progress in these research programmes.

The main technological challenge in converting this batch process into a continuous one is the acid hydrolysis reactor. After several attempts on conventional designs, a reactor based on a screw pump has been developed. This was a breakthrough in this project as the fibrous solids at low flowrates required to have long residence time posed a considerable technical challenge at the design stage.

The separation that required high g-force suggested a very expensive centrifuge. The hydrocyclone technology considered initially requires considerable flowrate to separate nanocrystals. A chance finding during the programme offered a solution to this problem. It was found almost by accident that the nanocrystal/acid mixture subjected to shear separates with time as if by gravity separation. The actual science behind this process is not yet fully understood (however, we have reported this in a publication). This finding led us to a practical, low cost solution of separating the crystals from the mother liquor. The separation process developed in place of centrifugation is at least five orders of magnitude better in energy efficiency.

The process equipment were designed and tested for functionality. It gives us the confidence that the process suggested now can run continuously.

A deviation from the suggested path was made during the project due to considering other processing options. A collaborative investigation with Prof Edward Lester (Promethean Particles Ltd), a colleague in the department, showed that continuous supercritical water hydrolysis also can be used to produce cellulose nanocrystals. This is a new finding that could have a considerable impact on the production of the nanocrystals using bio materials.

Generation of aerogels has several steps beginning with formation of hydrogels and then solvent exchange with ethanol to make alcogel and supercritical drying of the alcogel to produce aerogel. This process works on small samples but for larger volumes such as 100 cubic centimetre panel the conventional approach was not possible. During this project we have developed a procedure to achieve larger aerogel panels. This was done by slowly concentrating CNC dispersions in water to produce a mixture above the gelling threshold (40 mg/ml) and afterwards adding in a small amount of salt solutions as a gelling agent. The added salt screen the surface charges on nanocrystals allowing them to form a uniform gel network. The added salt will be removed after the solvent exchange with ethanol and therefore does not present an issue.

It was found during the project that the carbon nanocrystal have good thermal insulation properties. This has been explored in collaboration with Kingspan Insulation Ltd.
Exploitation Route Academic
The findings are and will be published in reputed journals focused on the nanomaterials community. The know-how generated within this project has been shared at conferences on the topic. Collaborations with Katholieke Universiteit Leuven (Kortrijk Campus) where the previous PI has moved to is planned to carry out further investigations, specially the supercritical hydrolysis.

The industrial take-up of cellulose nanocrystals has been hindered by the absence of a continuous production facility able to produce the desired materials at an industrially relevant scale. This research project showed that essential elements of the continuous process could be developed and operated successfully. Investigators will explore the possibility of collaborations with the industries the possibility of technology transfer.

Business Partnership Unit (BPU) in the School of Chemistry UoN has been looking for industrial partners to develop novel, high performance thermal insulation applications based on carbon nanocrystal aerogels, which has been shown to have very good thermal insulation properties. Through BPU Kingspan Insulation Ltd has been approached to investigate the use of carbon nanocrystal aerogels for thermal insulation.

We would continue to explore the possibility of commercialization of the carbon nanocrystal aerogels
Sectors Aerospace, Defence and Marine,Construction,Pharmaceuticals and Medical Biotechnology

Description EPSRC-DTG awards
Amount £52,568 (GBP)
Organisation University of Nottingham 
Department Faculty of Engineering
Sector Academic/University
Country United Kingdom
Start 09/2012 
End 09/2015
Title CNCXDatabase 
Description Currently collecting data through number of bench top experiments on the production of cellulose nano-crystals. The database contains the experimental condition and the output quality and volumes. This database will be augmented when the continuous production system is up and running with control parameters and yield. 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact Currently the database is incomplete. Once it is populated it will be open to all researchers to use and analyze. The database will contain unique information on continuous production parameters for cellulose nano-crystals. This will also generate the basis for scale up production facilities for commercialization. The data can be made public on request subjected to restrictions as some of the data is yet to publish. 
Description Collaboration with Building Research Establishment (BRE) 
Organisation Building Research Establishment
Country United Kingdom 
Sector Private 
PI Contribution Research team has been developing the methods to produce large volumes of cellulose nano crystals economically so that panels of aerogels could be produced. Furthermore, the team is to characterise the aerogels for thermal and mechanical properties. The contribution from the research team is to develop know-how and the commercialisable product.
Collaborator Contribution BRE has number of partners directly working on applications where the aerogels could be used. Therefore the BRE's contribution is towards commercialisation of the product. Furthermore, BRE would identify partners who could provide standard characterisation techniques and procedures.
Impact Two Technical briefings highlighting the applicability of aerogels made of Cellulose Nano-Crystals as effective thermal insulators.
Start Year 2012
Title Continuous production of nanocrystals 
Description This research is focused on developing a continuous process as oppose to the widely practiced batch process in manufacturing cellulose nano crystals. The process has been developed and tested in sections and has shown that the concept is sound even though the production rates are low. This low production rate can be addressed by optimizing the acid hydrolysis process. During the project it was found that the energy cost could be reduced by replacing the centrifugation with the shear induced sedimentation. prior to dialysis step. The used sulfuric acid recycle method also reduces the material cost even though have a considerable energy footprint. 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2016 
Impact (1) The process or parts there of could be adopted by the industrial sector (2) The new separation technique reduces the energy requirements for the process making the process cost effective. (3) Cellulose nanocrystals could be used as thermal insulation material