Nickel-Catalyzed Carbonization of Lignocresol to Produce Crystallized Carbon Usable for Electromagnetic Shielding

Lignocresol (LC), which is recovered from wood by adopting phase separation system with sulfuric acid/ cresol, was carbonized at 900°C for 1 h after loading with nickel alone or both nickel and sodium, and the crystal structure of carbon and the electromagnetic shielding (EMS) capacity at 50-800 MHz were evaluated for the resulting char. For comparison, four other isolated lignins were subjected to the same treatment and measurement. LC char could produce crystallized carbon (T-component) markedly by co-loading of nickel 8-9 wt% and sodium 8-10 wt% to exceed a practical standard of EMS capacity. 30 dB at 800 MHz, although nickel alone was ineffective. The capacity of the LC char with both nickel and sodium was superior or comparable to those of the corresponding other lignin chars. Without nickel, LC char resulting from the unique structure gave less amorphous carbon with larger EMS capacity than other chars. These results showed that LC was suitable as raw lignin for converting into EMS material by nickel-catalyzed carbonization.