A solid-state NMR, FT-IR and TPD study on acid properties of sulfated and metal-promoted zirconia: Influence of promoter and sulfation treatment

Wen Hua Chen, Hui Hsin Ko, Ayyamperumal Sakthivel, Shing Jong Huang, Shou Heng Liu, An Ya Lo, Tseng Chang Tsai, Shang Bin Liu

研究成果: Article同行評審

166 引文 斯高帕斯(Scopus)

摘要

The acid properties of various sulfated and metal-promoted zirconium oxide (ZrO2) catalysts have been studied by solid-state 31P MAS NMR, FT-IR and TPD using the adsorbed trimethylphosphine oxide (TMPO), pyridine and ammonia as the probe molecule, respectively. Sulfated zirconia (SZ) catalysts having varied sulfur contents and metal promoter (M = Al, Ga and Fe) were prepared by sol-gel method. Effects of sulfation and promoter on the detailed qualitative and quantitative information of acid sites, viz. types (Brønsted versus Lewis), strengths and distributions, on various synthesized SZ and M/SZ were examined by 31P MAS NMR of adsorbed TMPO in conjunction with elemental analyses by ICP-MS. By comparison, pyridine-IR and NH3-TPD methods are capable of providing only qualitative information of the overall acidity. It was found that while the parent ZrO2 possesses only weak Lewis acidities, elaborated sulfation treatment leads to formation and coexistence of strong Brønsted (B) and Lewis (L) acid sites whose variations can readily be followed. On the other hand, incorporation of different metal promoters onto SZ, led to simultaneous formation/elimination and variations of B- and L-sites with varied strengths and distributions. As a result, Ga/SZ was found to possess more B- than L-sites, whereas an opposite trend was observed for Al/SZ. As for Fe/SZ, a pronounced increase in both concentration and strength of acid sites were found. With an exception of Ga/SZ, the 'very strong' acid sites observed for various SZ and M/SZ catalysts were found to be associated more to L- than B-sites.

原文English
頁(從 - 到)111-120
頁數10
期刊Catalysis Today
116
發行號2 SPEC. ISS.
DOIs
出版狀態Published - 2006 8月 1

All Science Journal Classification (ASJC) codes

  • 催化
  • 化學 (全部)

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