Improving Yields and Catalyst Reuse for Palmitic Acid Aromatization in the Presence of Pressurized Water

Jeffrey R. Page, Heather O. Leclerc, Philip Smolitsky, Joseph P. Esposito, Douglas P. Theberge, Azadeh Zaker, Alex R. Maag, Sanket Sabnis, Edward B. Ledford, John Coleman, Wei Fan, Siwen Wang, Jesse Q. Bond, Bernardo Castro-Dominguez, Michael T. Timko

Research output: Contribution to journalArticlepeer-review

Abstract

ZSM-5 was evaluated for chemical production in a reaction mixture consisting of palmitic acid and water at conditions near the critical point of water (400 °C, 23 ± 2 MPa). Two types of ZSM-5, a microscale variety with particle diameters determined by scanning electron microscopy in the range from 1.66 to 2.56 μm (micro-ZSM-5) and a nanoscale variety with 350-730 nm diameters (nano-ZSM-5), and three water loadings (0, 15, and 65 wt %) were evaluated for their effects on conversion and product selectivity. Palmitic acid conversion and yields of one-ring aromatics, including toluene and xylenes, were greatest for the combination of nano-ZSM-5 and 15 wt % water loadings, showing that reducing particle size and optimizing water content help achieve desired reaction outcomes. Subsequently, the use of nano-ZSM-5 combined with 15 wt % water loading was studied in greater detail, finding that the catalyst could be reused up to four times at these conditions without reduction of aromatic yields and while retaining a fraction of the original acid sites. Time-resolved studies and molecular-level analysis using two-dimensional gas chromatography and isotopic resolution mass spectrometry provided information on the reaction pathway, which consists of a combination of homogeneous and heterogeneous steps. The results of this study motivate future work on water-promoted catalytic cracking of oils to produce valuable chemicals.

Original languageEnglish (US)
Pages (from-to)5659-5673
Number of pages15
JournalACS Sustainable Chemistry and Engineering
Volume10
Issue number17
DOIs
StatePublished - May 2 2022

Keywords

  • aromatic hydrocarbons
  • BTEX
  • pressurized water
  • zeolites

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment

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