Project: Coal char as a substituting material of natural graphite in green energy technologies

Duration 01/04/2016 - 30/09/2019
Project Topic Graphite is a mineral of strategic importance for European Union. However, every year millions of tons of unburned semi-coked carbon (CHAR) produced by the coal power plants are landfilled or added to concrete with negative impacts, while CHAR could be used as a SUBSTITUTING MATERIAL of NATURAL GRAPHITE. Therefore, CHARPHITE project aims at: (i) concentrate and purify char from coal ash using classic separation methods and ultrasonication; (ii) producing composite metallic oxides with CHAR, and carry a comprehensive electrochemical characterization of the novel carbon materials to be tested as electrode materials (electrocatalysts) for relevant energy-related reactions; (iii) performing industrial research to use these carbon materials as an additional supply source for the production of graphite electrodes and rods
Project Results
(after finalisation)
The project aimed to demonstrate the technical feasibility to utilize coalCHAR recycled from fly ash andbottom ash as a substitute for graphite based materials for applications as catalysts in electro assistedreactions for sustainable energy production oxygen reduction reaction ( for fuel cell technologyand water splitting Coal combustion ash samples from Portugal, Poland, Romania and South Africa were selected todetermine a suitable separation procedure Following ash characterization, the chars were extractedusing several combinations of particle size, elutriation electrostatic, and magnetic separation steps Thefinal product grade was up to 75 wt carbon The anisotropy percentages of the samples rangedbetween 22 and 49 the reference natural graphite sample had anisotropy of 86 and Ramanmicrospectroscopyclassified the char concentrates as being “ with the possibility as aprecursor for synthetic graphite 7 Project CHARPHITE Coal char as a substituting material of natural graphite in green energy technologies Fly ash samples from different sources and size fractions were selected to prepare solid acid catalysts tobe used in the transformation ofbiomass derivatives into fuel additives and biofuels production,including esterification of levulinic acid for the preparation of n butyl levulinate n Butyl levulinate wasunique product with conversions up to 100 after 40 min reaction The most promising catalyststudied also exhibited the highest TOFs 447 h 1 and showed to be the most stable and reusable for 5 consecutive catalytic cycles The 13 C ss NMR experiment shows all the expected carbon resonancesignals according to the chemical modification performed The use of CFA from different sources anddifferent particles sizes endeavor to evaluate the potential effect of i different particle sizes ii) metaloxides composition and carbon content in the final functionalization and catalytic esterification activity For the electrocatalytic studies, each fly ash was separated by size 25 45 75 and 150 um and testedfor the ORR All samples showed a dependency between the ORR electrocatalytic activity and theparticles size/ composition For char concentrates, demineralized char concentrates and graphitized char concentrates, in N 2 saturated electrolyte, no electrochemical processes are observed for all the samples tested, includinggraphene flakes ( whereas, in the presence of O 2 all samplesshowed an irreversible reduction peakat 0 63 ≥ 0 75 corresponding to the reduction of oxygen For the set of concentrated and furthercarbonized samples two samples showed number of electrons transferred per O 2 molecules withñ 2 7 and 2 8 suggesting a mix 2 4 electron pathway For concentrated and demineralized chars followed by graphitization, the best result was ñ of 3 0 eventhough lowerjLandEonsetvalues were obtained The electrocatalytic results obtained show that theproject goal touse chars derived from coal fly ash and coal bottom ash as a substitute for graphite based materials in green energy applications was achieved, and all materials were successfully used inthe electro assisted energy reaction oxygen reduction reaction ( Preliminary tests to assess future work were made using laboratory technology of CHAR carbonizationrecovered from the low rank coals and laboratory technology of CHAR pre graphitization in microwavefield from high rank coals Tests were made on inorganic residues left for both lightweight construction materials, as well as forhydraulic or ceramic bonding, for different types of by products and the results were promising, thuscontributing to sustainable waste management and zero waste directives
Website visit project website
Network ERA-MIN
Call The Third ERA-MIN Joint Call (2015)

Project partner

Number Name Role Country
1 University of Porto Coordinator Portugal
2 University Politehnica Bucharest Partner Romania
3 REQUIMTE Partner Portugal
4 CONICET & University of Buenos Aires Partner Argentina
5 University "Constantin Brancusi" of Targu Jiu Partner Romania
7 CARBO-GRAF SP. Z O.O. Partner Poland
8 University of Johannesburg Partner South Africa
9 Pegop – Energia Eléctrica, S.A. Observer Portugal