(425c) Indium Oxide with SAPO-34 Bifunctional Catalyst for CO2 Hydrogenation to Light Olefins

Light olefins (C₂–C₄) can be produced from CO₂ hydrogenation by bifunctional catalyst via methanol intermediate route of which CO₂ is first converted to methanol on metal oxides followed by methanol-to-olefins (MTO) reaction on zeolite in a single reactor. This process can produce higher C₂–C₄ olefins selectivity than a modified Fischer–Tropsch synthesis (FTS) route. In the present work, indium supported on ZrO₂ was mixed with SAPO-34, and the catalysts were evaluated for direct CO₂ hydrogenation at a temperature range from 300 ºC to 400 ºC at 30 bar. Our results show that 10 wt.% In/ZrO₂ has a CO₂ conversion of 7.0%, 17.4%, and 32.9% at the reaction temperature of 300 ºC, 350 ºC, and 400 ºC, respectively. At the temperature of 350 ºC, the space-time yield (STY) has the highest value of 1.25 mmol/h/g among the scanned temperatures, and the selectivity of CO, CH₄, olefins, and paraffins is 60.7%, 1.1%, 21.3%, and 16.9% at 350 ºC, respectively. The major produced gas of CO related with the reverse-water gas shift reaction can be minimized, and the activity and light olefins selectivity can be increased by incorporating promoters and controlling interaction between In/ZrO₂ and SAPO-34. In this presentation, we will illustrate a detailed characterization of the catalyst using electron microscopy and x-ray spectroscopy, discuss the reaction mechanism of the catalyst, and elucidate the effect of promoter and catalyst structure on olefins selectivity.