Application of Zn/Zsm-5 as Coke-Resistant Catalyst for Acetylene Acetoxylation

Abstract

ZSM-5 (Z) with different silica-aluminum ratio was applied as support for Zn catalyst for acetylene acetoxylation. The acetic acid conversion increased with increase of silica-aluminum ratio and Zn/Z(SI) exhibited the highest CH3COOH conversion of 85%, being similar with active carbon (AC) supported Zn catalyst. However, Zn/Z(SI) showed excellent stability, CH3COOH conversion only decreased 15% after running 225 h, much better than the 32% of Zn/AC after 60 h. The used Zn/Z(SI) and Zn/AC catalysts were characterized and compared with fresh catalysts. There was no much difference of crystalline structure, particle aggregation and actual Zn content between the used Zn/Z(SI) and Zn/AC catalysts. TG, CH3COOH -TPD and XPS characterizations revealed the interaction between Z(SI) and Zn will increase the electron density around Zn to facilitate the adsorption of CH3COOH, thus inhibited the carbon deposition. Zn/Z(SI) catalyst could be regenerated by calcination in air atmosphere due to the thermal stability of ZSM-5.

Keywords: acetylene acetoxylation, ZSM-5, carbon deposition