Recycling and reuse performance of cobalt catalyst for coal hydrogasification

•Acid leaching was used to recover Co catalyst from coal hydrogasification residue.•HNO3-leached efficiency of cobalt exceeded 99.7% in each closed-loop cycle.•Enrichment behaviors of 17 impurities in the recovered solution were revealed.•Effects of Fe, Al, K, Na, Mg, P, and S impurities on Co–Ca activity were assessed.•Using selective precipitation to remove impurities and regenerate Co–Ca activity.