Customizing high-performance molten salt biochar from wood waste for CO2/N2 separation

Mingzhe Sun, Xiefei Zhu, Chunfei Wu, Ondrej Masek, Chi Hwa Wang, Jin Shang, Yong Sik Ok, Daniel C.W. Tsang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Engineered biochar derived from wood waste pyrolysis in molten salts were developed for effective CO2/N2 separation. The production conditions were customized to obtain the biochar with high CO2 capture capacity and CO2/N2 selectivity by tuning the type of molten salts (MgCl2-KCl, ZnCl2-KCl, ZnCl2-NaCl-KCl, and K2CO3-Na2CO3-Li2CO3), salt/feedstock ratios (1:1 and 3:1) and pyrolysis temperatures (600 and 800 °C). High temperature (800 °C) and moderate salt loading (salt/feedstock ratio of 1:1) benefited the CO2 adsorption by providing an increased surface area and highly dispersed metal species as adsorption sites. PSL-3-800 and PSL-3-600 (K2CO3-Na2CO3-Li2CO3 biochar) showed the highest CO2 capacity (4.5 mmol g−1, 0 °C, 100 kPa) and the highest CO2/N2 selectivity (28.5), respectively, among the engineered biochar developed in this study. In addition, ZP-3-600 showed the highest selection parameter (S) in both PSA and VSA processes, indicating the promising CO2 capture performance under PSA/VSA conditions. A high recovery rate (89%) of molten salts was achieved. These results suggest a new pathway for upcycling biowaste as eco-friendly and effective adsorbents for gas adsorption and separation.

Original languageEnglish
Article number107319
JournalFuel Processing Technology
Publication statusPublished - 2022 Sept


  • Biochar adsorbent
  • Biochar-mineral composite
  • CO capture
  • Carbon sequestration
  • PSA/VSA assessment
  • Waste recycling

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology


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