CSIR researchers are exploring the synthesis, modification and composting of porous carbonaceous materials for hydrogen storage applications. 

Materials-based storage technologies are reported to be a promising preference for hydrogen storage, especially when using materials with attractive porosity and controllable pore size distribution. Some of the porous materials of interest include templated carbons, metal organic frameworks (MOFs), activated carbons and graphene, among others. Bearing in mind that the key properties that make these materials attractive for hydrogen storage are derived from their porosities, high surface areas, and relatively large micro-pore volumes, the main challenge inhibiting their scale-up production there is the potentially high cost of production. Therefore, there is a need for investigation of the possibility for use of low-cost unconventional synthesis feedstock. 

In this project, the main focus is on the production of templated carbons, metal organic framework-derived carbons, graphene and activated carbons, especially those derived from low-cost starting feedstocks such as waste tyres, clays and other unconventional starting materials. There is also interest in the development of carbon composite materials and shaping technologies (such as electrospinning, granulation and pelletisation) that would enable fabrication of application-specific properties. These shaping strategies will enable enhancement of hydrogen storage capacity, bulk density, thermal conductivity and stability of hydrogen storage materials.

This project has identified several strategies that could enable production of attractive carbonaceous materials at relatively lower cost. Researchers are looking into different approaches.

The first approach is the use of coal combustion by-products (such as fly ash) and clays as feedstock materials for synthesising low-cost zeolites that can be used to produce high surface area templated carbons. Recent studies conducted at the HySA Infrastructure Competence Centre have shown great potential for the use of South African fly ash and clays as valuable feedstock for producing porous carbons. 

Synthesis of novel carbons from the pyrolysis of waste tyres is also proposed to provide a cost-effective and environmentally friendly way of producing hydrogen storage materials. According to the Recycling and Economic Development Initiative of South Africa, about 11 million waste tyres are added to the existing dumps and stockpiles every year.  The approach of producing high- value carbons from waste tyres will not only play a role in eradicating the problem of waste tyres landfills in South Africa, but also provide attractive and low-cost materials for storing hydrogen. 

An additional research interest involves the synthesis of carbon composites especially those containing metal organic frameworks. The composite materials are being shaped and/or immobilised by different techniques such as electrospinning, granulation and pelletisation. Shaping of these materials plays an important role in transitioning from laboratory to application-specific properties that are aimed for real practical applications. 
Even though the primary consumer of the developed material-based systems will mainly be industries that are in the line of gas storage/capture (hydrogen, methane, carbon dioxide etc.), there are still other potential applications such as in water treatment as well as uses in the petrochemical industries.

Work in this project is undertaken by HySA Infrastructure and constitutes part of the Department of Science and Technology’s Hydrogen and Fuel Cell Technologies Programme (Hydrogen South Africa or HySA).