Tuning adsorption properties of GaxIn2−xO3 catalysts for enhancement of methanol synthesis activity from CO2 hydrogenation at high reaction temperature

• Main Authors: Akkharaphatthawon, Naphattanun, Chanlek, Narong, Cheng, C. K., Chareonpanich, Metta, Limtrakul, Jumras, Witoon, Thongthai
• Format: Article
• Language: English
• Published: Elsevier 2019
• Subjects: QD Chemistry; TP Chemical technology
• Online Access: http://umpir.ump.edu.my/id/eprint/25373/1/Tuning%20adsorption%20properties%20of%20GaxIn2%E2%88%92xO3%20catalysts%20.pdf; http://umpir.ump.edu.my/id/eprint/25373/; https://doi.org/10.1016/j.apsusc.2019.05.363; https://doi.org/10.1016/j.apsusc.2019.05.363

Light olefins can be produced from CO2 hydrogenation in a single reactor using a combination of a methanol synthesis catalyst and a methanol-to-olefin (MTO) catalyst. However, commercial methanol synthesis catalysts are active at low temperatures (200–260 °C), while MTO reaction is feasible at higher temperatures (>300 °C). Herein, we report the CO2 hydrogenation to methanol at high temperatures (320–400 °C) over GaxIn2−xO3 catalysts. By tuning the Ga/In ratios, phase, crystallinity, pore structure, morphology, electronic properties as well as adsorptive properties of GaxIn2−xO3 catalysts can be modified. At the lowest temperature (320 °C), the pure In2O3 shows the highest methanol yield. However, the maximum methanol yield declines significantly with increasing reaction temperatures. Incorporation of Ga into the In2O3 crystal lattices at x = 0.4 (Ga0.4In1.6O3) maximizes the methanol yield at higher reaction temperatures of 340–360 °C. This enhancement can be attributed to an increased binding energy of adsorptive molecules with the catalyst surface to promote the hydrogenation of CO2 to methanol. Further increasing Ga content (x > 0.4) leads to greatly strengthen the binding for adsorptive molecules, resulting in a lower methanol yield and the formation of methane. The surface chemisorbed oxygen is found to be a key factor determining the CO yield.