Abstract: A series of Cu-Zn-Al catalyst samples were prepared by sol-gel method with the assistance of polyethylene glycol (PEG) additive. The effect of PEG dosage on their physical and chemical properties was characterized by X-ray diffraction, N₂ adsorption, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction, and NH₃ temperature-programmed desorption. The catalytic performance of the catalyst for direct dimethyl ether (DME) synthesis from syngas was evaluated in a slurry reactor. The results showed that PEG can improve the texture and surface physical and chemical properties of the catalyst and therefore enhance its catalytic activity. With the increase of PEG dosage, the specific surface area, pore volume, and pore diameter of the catalyst increased, whereas the reduction temperature decreased first and then increased, and the dispersion of active component, surface Cu content, and strong acid amount first increased and then decreased. However, adding PEG can only enhance catalytic activity and selectivity of the catalyst, but has no effect on the catalyst stability.

Key words: polyethylene glycol, copper, zinc, aluminium, sol-gel, syngas, dimethyl ether