Carbon monoxide (CO) is a representative platform compound that can be transformed to various base and fine chemicals. However, CO manufactured by the conventional methods includes many other gases such as hydrogen, methane, nitrogen and carbon dioxide, and additional separation processes are required to utilize CO as a raw material. Unfortunately, the current state-of-the-art techniques for separating CO have problems such as high energy consumptions, and needs for alternate separation. In this work, we developed a nickel-based adsorbent supported on petroleum-based activated carbon (PAC, BET >$1,300 m^2/g$) to maximize the dispersion of nickel on the support. Ni/PAC was additionally doped with sulfur to increase the CO adsorption activity, and the sulfur-doped Ni/PAC showed outstanding CO adsorption/desorption activity 10 times higher than that of the sulfur-free Ni/carbon adsorbent. CO processed through sulfur-doped Ni/PAC was recovered in more than 99% in purity.