Catalytic process development strategies for conversion of propane to liquid hydrocarbons

The temperature effect on propane dehydroaromatization pathways on the PtZn/SiO2 +ZSM-5 bifunctional catalysts is investigated to develop strategies for propane conversion to valuable liquid hydrocarbons. At high temperature (550 degrees C), high dehydrogenation rates and lower monomolecular cracking rates are required to minimize methane formation, leading to primarily propene and BTX (benzene, toluene, and xylenes). By recycling propene in the propane conversion range of 30-45%, > 80% BTX yields is likely achievable at full recycle. At mid temperature (400-450 degrees C), the product has high selectivity to gasoline-blending hydrocarbons (butanes, C5+ hydrocarbons, toluene, and xylenes) at 15-25% propane conversions because dehydrogenation rates are moderately high, and oligomerization is more favored than cracking. At low temperature (350 degrees C), -25% propane conversion is achieved and has high selectivity (-60%) to butanes, but the propane conversion rates are likely too low to be practical. While methane formation by monomolecular cracking limits liquid yields at high reaction temperature, hydrogen co-produced at high propane conversions saturates light olefins to make undesired ethane, which becomes major yield loss reaction on the PtZn/SiO2 +ZSM-5 at mid and low temperatures.