1. Institute
for Energy and Transport, Joint Research Centre, European Commission, Westerduinweg 3, 1755 LE Petten, The Netherlands
2. Instituto Nacional del Carbon, C/Francisco Pintado Fe 26, La Corredoria, 33011 Oviedo, Spain
3. Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Block 107, 1113 Sofia, Bulgaria