Methane Upgrading of Acetic Acid as a Model Compound for a Biomass-Derived Liquid over a Modified Zeolite Catalyst

Matthew Yung, Aiguo Wang, Danielle Austin, Abhoy Karmakar, Guy Bernard, Vladimir Michaelis, Hongbo Zeng, Hua Song

Research output: Contribution to journalArticlepeer-review

41 Scopus Citations

Abstract

The technical feasibility of coaromatization of acetic acid derived from biomass and methane was investigated under mild reaction conditions (400°C and 30 bar) over silver-, zinc-, and/or gallium-modified zeolite catalysts. On the basis of GC-MS, Micro-GC, and TGA analysis, more light aromatic hydrocarbons, less phenol formation, lower coke production, and higher methane conversion are observed over 5%Zn-1%Ga/ZSM-5 catalyst in comparison with catalytic performance over the other catalysts. Direct evidence of methane incorporation into aromatics over 5%Zn-1%Ga/ZSM-5 catalyst is witnessed in 1H, 2H, and 13C NMR spectra, revealing that the carbon from methane prefers to occupy the phenyl carbon sites and the benzylic carbon sites, and the hydrogen of methane favors the aromatic and benzylic substitutions of product molecules. In combination with the 13C NMR results for isotopically labeled acetic acid (13CH3COOH and CH313COOH), it can be seen that the methyl and carbonyl carbons of acetic acid are equally involved in the formation of ortho, meta and para carbons of the aromatics, whereas the phenyl carbons directly bonded with alkyl substituent groups and benzylic carbons are derived mainly from the carboxyl carbon of acetic acid. After various catalyst characterizations by using TEM, XRD, DRIFT, NH3-TPD, and XPS, the excellent catalytic performance might be closely related to the highly dispersed zinc and gallium species on the zeolite support, moderate surface acidity, and an appropriate ratio of weak acidic sites to strong acidic sites as well as the fairly stable oxidation state during acetic acid conversion under a methane environment. Two mechanisms of the coaromatization of acetic acid and methane have also been proposed after consulting all the collected data in this study. The results reported in this paper could potentially lead to more cost-effective utilization of abundant natural gas and biomass. (Figure Presented).

Original languageAmerican English
Pages (from-to)3681-3692
Number of pages12
JournalACS Catalysis
Volume7
Issue number5
DOIs
StatePublished - 5 May 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-5100-68691

Keywords

  • acetic acid
  • aromatization
  • catalyst
  • methane
  • ZSM-5

Fingerprint

Dive into the research topics of 'Methane Upgrading of Acetic Acid as a Model Compound for a Biomass-Derived Liquid over a Modified Zeolite Catalyst'. Together they form a unique fingerprint.

Cite this