High activity Ru catalyst was prepared for the first time to produce cis‐decalin from tetralin hydrogenation. Supercritical CO2‐methanol method was used to prepare Ru supported catalyst. Using this catalyst, the yield of cis‐decalin could reach as high as 92.52%. Furthermore, the catalyst remained a high activity after five cycles.

Carbon dioxide (CO2) was firstly used to precipitate Zn ions with urea to prepare zinc oxide (ZnO). The advantages of this method were small particle size, high yield and low sensitivity to conditions, such as temperature and time, and the decrease of solvent consumption. Further, the influence of carbon dioxide pressure, reaction time and temperature were studied and optimized.