Enhancement of Carbon dioxide adsorption capacity on synthesized oxygen-doped nanocarbons via solution plasma process and nitridation

摘要

Recently, the adsorption of carbon dioxide (CO_2) on solid sorbent is now focused since it overcomes the drawbacks of previous conventional CO_2 capture process by CO_2 scrubbing via liquid amine, in terms of lower energy requirements for regeneration and ease of separation. Carbon-based sorbent has high potential to make this done due to its high surface area to its volume ratio, as well as high thermal and chemical stability. In this report, oxygen-doped nanocarbon (o-CN) was synthesized from a homogeneous mixture of benzene and metal working fluid (MWF) via in-liquid plasma process, so called solution plasma process (SPP). Then it was nitrided under ammonia atmosphere at high temperature (800 °C) to enhance its capacity. CO_2 adsorption was done by volumetric analysis at 25 °C. The experimental results revealed that CO_2 adsorption capacity was increased by nitridation by creating microporosity and nitrogen-containing functional groups on the sorbent. The maximum capacity was achieved at 1.63 mmol g~(-1) on nanocarbon synthesized from benzene mixed with 15 vol% MWF, nitrided at 800 °C (no-CN) which was greater than nanocarbon synthesized by pure benzene about 5-fold. The study of thermodynamics revealed that the CO_2 adsorption on no-CN was exothermic, less random and exergonic. Nitrided sorbent showed more negative isosteric enthalpy of adsorption than pristine carbon referring to stronger binding forces to sorbate molecule. Moreover, no-CN exhibited a better selectivity of CO_2 adsorption than of N2, and it can withstand on multi-cycle use.