The invention discloses an S / N co-doped microporous carbon adsorbent as well as a preparation method and application thereof, and belongs to the technical field of adsorbents. According to the method, firstly,
melamine is utilized to enable waste
polyvinyl chloride to be subjected to dechlorination reaction at
room temperature to generate a microporous carbon material precursor, then
decomposition and structural recombination of the microporous carbon material precursor are promoted through high-temperature
pyrolysis, the generated local stress further increases the number of carbon defects, the carbon defects are in a high-energy state at high temperature, and the carbon defects are in a high-energy state at high temperature. And gas escape or further
chemical reaction is easy to occur. Meanwhile, the activating agent is decomposed at high temperature and releases a large amount of
small molecule gas to promote generation of
carbon skeleton pores, and non-carbonizable PVC is converted into a high-value
nitrogen-
doped carbon material. And finally mixing
thiourea, modifying the microporous carbon material by introducing a
sulfur element, and further optimizing the polarity of the carbon surface by
heteroatom doping, so that the CO2 adsorption performance is remarkably improved, and the
sulfur-functionalized
porous carbon adsorbent with high microporosity is constructed.