# Preparation of Fe-HMOR with a Preferential Iron Location in the 12-MR Channels for Dimethyl Ether Carbonylation

## TL;DR

This paper shows how adding iron to a specific part of a catalyst improves its performance in a chemical reaction that converts dimethyl ether into useful products.

## Contribution

A new method to selectively place iron in 12-MR channels of MOR, enhancing Brønsted acid sites in 8-MR for DME carbonylation.

## Key findings

- Fe atoms substituted Al in 12-MR channels due to the EDTA–Fe complex size.
- Optimal Brønsted acid sites in 8-MR were achieved at Fe/Si = 0.01.
- Fe-modified MOR showed three times higher DME carbonylation activity than HMOR.

## Abstract

As the Brønsted acid sites in the 8-membered ring (8-MR) of mordenite (MOR) are reported to be the active center for dimethyl ether (DME) carbonylation reaction, it is of great importance to selectively increase the Brønsted acid amount in the 8-MR. Herein, a series of Fe-HMOR was prepared through one-pot hydrothermal synthesis by adding the EDTA–Fe complex into the gel. By combining XRD, FTIR, UV–Vis, Raman and XPS, it was found that the Fe atoms selectively substituted for the Al atoms in the 12-MR channels because of the large size of the EDTA–Fe complex. The NH3-TPD and Py-IR results showed that with the increase in Fe addition from Fe/Si = 0 to 0.02, the Brønsted acid sites derived from Si-OH-Al in the 8-MR first increased and then decreased, with the maximum at Fe/Si = 0.01. The Fe-modified MOR with Fe/Si = 0.01 showed the highest activity in DME carbonylation, which was three times that of HMOR. The TG/DTG results indicated that the carbon deposition and heavy coke formation in the spent Fe-HMOR catalysts were inhibited due to Fe addition. This work provides a practical way to design a catalyst with enhanced catalytic performance.