Issue 6, 2023

A computational investigation of the decomposition of acetic acid in H-SSZ-13 and its role in the initiation of the MTO process

Abstract

The zeolite-catalyzed reaction of acetic acid is important in the direct utilization of biomass and also plays a role in the reactivity of oxygenates in the methanol-to-olefins (MTO) process. The conversion of acetic acid to acetone involves the coupling of two acetic acid molecules to a β-ketoacid (3-oxobutanoic acid) in a first step, which can then be decarboxylated to acetone. Further possible reactions include the aldol self-condensation of acetone to mesityl oxide, which can subsequently decompose to isobutene and acetic acid. We investigate reaction pathways in H-SSZ-13 from acetic acid to isobutene using periodic density functional theory in combination with DLPNO-CCSD(T) calculations on cluster models. For the formation of 3-oxobutanoic acid, we propose a mechanism including the coupling of a ketene and a surface acetate with free energy barriers of 197 kJ mol−1 at most. Further free energy barriers leading to isobutene are lower. Studying reaction kinetics with a batch reactor model at 400 °C, we find fast conversion of acetic acid to acetone, which is a stable intermediate. The further reaction to isobutene is slower. In addition, we perform kinetic simulations which predict a minor relevance of these reactions for the initiation of the MTO process.

Graphical abstract: A computational investigation of the decomposition of acetic acid in H-SSZ-13 and its role in the initiation of the MTO process

Supplementary files

Article information

Article type
Paper
Submitted
14 Oct 2022
Accepted
22 Feb 2023
First published
06 Mar 2023
This article is Open Access
Creative Commons BY license

Catal. Sci. Technol., 2023,13, 1905-1917

A computational investigation of the decomposition of acetic acid in H-SSZ-13 and its role in the initiation of the MTO process

P. Huber and P. N. Plessow, Catal. Sci. Technol., 2023, 13, 1905 DOI: 10.1039/D2CY01779B

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