CO2 hydrogenation to dimethyl ether over In2O3 catalysts supported on aluminosilicate halloysite nanotubes

This work presents results on CO2 hydrogenation to dimethyl ether (DME) over bifunctional catalysts consisting of In2O3, supported on natural clay halloysite nanotubes (HNT), and HNT modified with Al-MCM-41 silica arrays. The catalysts were characterized by TEM, STEM, EDX-mapping, NH3-TPD, XRD, low-temperature nitrogen adsorption, TPO, and H-2-TPR techniques. Catalytic properties of In2O3/HNT and In2O3/Al-MCM-41/HNT in the CO2 hydrogenation to DME were investigated in a fixed-bed continuous flow stainless steel reactor at 10-40 atm, in the temperature range of 200-300 degrees C, at GHSV = 12,000 h(-1) and molar ratio of H-2:CO2 = 3:1. The best catalyst for CO2 hydrogenation was In2O3/Al-MCM-41/HNT that provided DME production rate 0.15 g(DME).(g(cat).h)(-1) with DME selectivity 53% and at 40 bar, GHSV = 12,000 h(-1), and T = 250 degrees C. It was shown that In2O3/Al-MCM-41/HNT exhibited stable operation for at least 40 h on stream.

Automated summary

By optimizing the loading of In2O3 catalyst and surface modification, the catalytic performance for CO2 hydrogenation to DME was effectively improved. The best catalyst, In2O3/Al-MCM-41/HNT, showed high production rate and selectivity under high temperature and pressure conditions, as well as good stability for at least 40 hours of operation.