Covalent bonding of sulfogroups to activated carbon fibers: The role of bromine plasma pretreatment

ABSTRACT

Activated carbon fibers―nanographite systems, where graphene sheets of a size of a few nanometers are stacked into the porous structure, can serve as adsorbents and catalysts. For a successful catalytic application, graphene surface structures were intensively halogenated with bromine plasma and liquid bromine and then introduced sulfogroups at the brominated sites of the surface through a wet chemical route. The surface chemistry changes were controlled with thermal analysis methods. The catalytic SO₃H groups, which covalent attachment was completed at the expense of the plasma-brominated sites, show the highest thermal stability and enhanced activity in catalytic dehydration. In particular, the propan-2-ol conversion to propene reaches 100% at 190–200 °C and the dehydration can be repeatedly conducted at a temperature below 250 °C.

KEYWORDS:

• Nanoporous activated carbon fibers
• plasma bromination
• propan-2-ol dehydration
• sulfogroups
• thermodesorption

Acknowledgments

The authors would like to thank Dr. V.V. Trachevskyi from The National Aviation University in Kyiv for the research assistance. V.V.L. acknowledges the National Scholarship Programme of the Slovak Republic managed by SAIA, n.o. for the support granted in 2015 and 2017.