From destructive CCl₄ adsorption to grafting SO₃H groups onto activated carbon fibers

Abstract

Nanoporous activated carbon fibers (Busofit^TM, BACF) showed effective adsorption of carbon tetrachloride (CTC) vapors. About 2.50 mmol × g⁻¹ of chlorine, in the form of trichloromethyl and chlorine groups, can be grafted onto BACF surface by thermal decomposition of CTC at 450 °C. To obtain solid acids, this chlorinated BACF, the brominated and pristine BACFs, taken for comparison, were subjected to progressive sulfidation, hydrolysis and oxidation reactions for grafting sulfonic groups. By this wet route, sulfonic groups can substitute only 1.1–1.4 mmol × g⁻¹ of the grafted chlorine groups. Nevertheless, solid acids obtained in this way have high catalytic performance in the 2-propanol dehydration to propene. For these catalysts, in the range from 180 to 220°C, a 100% alcohol conversion with 100% selectivity to propene could be reached. Thermoprogrammed desorption and thermal analysis revealed that the pyrolytic chlorination triggers the highest thermal stability of grafted sulfonic groups, and, they can repeatedly act in the dehydration reaction.

Keywords:

• Nanoporous activated carbons
• Pyrolytic chlorination
• Sulfonic groups
• Thermodesorption
• 2-Propanol dehydration

Acknowledgments

This work was funded by Grants of the Ministry of Education and Science of Ukraine [0111U006260], [0114U003554], and [0116U002558]. V.V.L. thanks the National Scholarship Program of the Slovak Republic for the Mobility of Students, Ph.D. Students, University Teachers, Researchers and Artists, Slovak Academic Information Agency (SAIA), n. o., Grants in 2017 [20917], in 2015 [14511]; and International Visegrad Fund for scholarship, ID number [51810574] in 2018. O.Yu.B thanks the financial support from the National Scholarship Program of Slovak Republic (NSP), Slovak Academic Information Agency (SAIA), n.o., Grant in 2018 [24528].