Mechanistic understanding of methanol carbonylation: Interfacing homogeneous and heterogeneous catalysis via carbon supported Ir–La

Alyssa J.R. Hensley, Jianghao Zhang, Ilka Vinçon, Xavier Pereira Hernandez, Diana Tranca, Gotthard Seifert, Jean Sabin McEwen, Yong Wang

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The creation of heterogeneous analogs to homogeneous catalysts is of great importance to many industrial processes. Acetic acid synthesis via the carbonylation of methanol is one such process and it relies on a difficult-to-separate homogeneous Ir-based catalyst. Using a combination of density functional theory (DFT) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, we determine the structure and mechanism for methanol carbonylation over a promising single-site Ir–La/C heterogeneous catalyst replacement. Here, the Ir center is the active site with the acetyl-Ir complex being a rate controlling intermediate. Furthermore, the La both atomically disperses the Ir and acts as a Lewis acid site. In fact, the La promoter in the Ir–La/C catalyst was found to behave similarly to homogeneous promoters by abstracting an iodine from the Ir center and accelerating the CO insertion step. Overall, this work provides key insight into the atomistic nature of the Ir–La/C single-site catalyst and allows for the further design and optimization of single-site heterogeneous catalysts.

Original languageEnglish
Pages (from-to)414-422
Number of pages9
JournalJournal of Catalysis
Volume361
DOIs
StatePublished - May 2018

Keywords

  • Attenuated total reflectance-Fourier transform infrared spectroscopy
  • Density functional theory
  • Ir–La complex
  • Methanol carbonylation
  • Promoter effects
  • Single-site heterogeneous catalyst

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