Enhanced activity and stability of SO42�/ZrO2 by addition of Cu combined with CuZnOZrO2 for direct synthesis of dimethyl ether from CO2 hydrogenation

• Main Authors: Witoon, T., Numpilai, T., Dolsiririttigul, N., Chanlek, N., Poo-arporn, Y., Cheng, C.K., Ayodele, B.V., Chareonpanich, M., Limtrakul, J.
• Format: Article
• Published: 2022
• Online Access: http://scholars.utp.edu.my/id/eprint/34014/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85127736164&doi=10.1016%2fj.ijhydene.2022.03.150&partnerID=40&md5=39c32fac4b43b9be1de7a06bb8bb595e

Cu-modified SO42�/ZrO2 catalysts (XCu-SZ) with different Cu loading contents were prepared by sulfation of ZrOCl2·8H2O with (NH4)2SO4 to form SO42�/ZrO2 (SZ) followed by impregnation of SZ with a Cu precursor. The resulting XCu-SZ catalysts combined with a CuO�ZnO�ZrO2 catalyst were tested for CO2 hydrogenation to dimethyl ether (DME). The results indicated that the unmodified SZ catalyst exhibited the maximum DME yield (3.7) which was 2.0�2.6 times higher than the DME yield of all XCu-SZ catalysts at the beginning of reaction. However, the DME yield over the unmodified SZ catalyst rapidly decreased, while that of all XCu-SZ catalysts gradually increased during the time-on-stream experiment. After 100 h, the 6 wt Cu-modified SZ catalyst achieved the maximum DME yield of 3.2 at 260 °C and 20 bar, while the DME yield of the unmodified SZ catalyst was only 2.5. The NH3-TPD and XPS analyses indicated that more strong acid sites were present on the unmodified SZ catalyst, resulting in a coke formation and thus the rapid deactivation. For the XCu-SZ catalysts, Cu0 was formed on the surface of SZ after the reduction with H2 which accounted for the active site of hydrogenolysis of methanol to methane. During the time-on-stream experiment, Cu0 was progressively transformed to Cu2S through poisoning, leading to the continued increase of DME yield. © 2022 Hydrogen Energy Publications LLC