Rhodium–Chitosan Composites Supported on Magnesium–HZSM-5 in the Conversion of Dimethyl Ether to Lower Olefins

The catalytic properties of composite catalyst systems based on zeolite HZSM-5 modified with magnesium, rhodium, and chitosan have been studied. The introduction of a rhodium–chitosan composite has a significant effect on the catalytic properties of the zeolite catalyst providing a significant increase in the activity and stability of the catalyst. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has revealed that the use of chitosan leads to a decrease in the total acidity of the zeolite catalyst mostly owing to a decrease in the number of strong Brønsted acid sites. It has been shown that the pretreatment of Mg–Rh*chitosan–HZSM-5 with synthesis gas leads to an increase in the time-on-stream stability of the catalyst.