(191d) De-Oxygenation Catalysis for Gasoline Production On Titania

Short carbon chain oxygenates are formed as by products when syngas is converted to mixed alcohols on Molybdenum (1) or Rhodium (2) based catalytic systems. These oxygenates are usually acetone, acetic acid, ethyl acetate and acetaldehyde apart from alcohols. While mixed alcohols can be easily converted to gasoline on H+/ZSM-5, considerable coking is formed when other oxygenates are used (particularly acetic acid). Hence a titania based catalytic system is being examined to convert the non-alcohol oxygenates to gasoline range hydrocarbon on a single multifunctional catalyst. The reactions are performed in similar conditions where alcohol to gasoline reaction is most productive.

Aldol condensation of acetone to mesitylene was examined at high pressure conditions. It was shown that a physical mixture of Titania and H+/ZSM-5 can produce good yield of gasoline range hydrocarbon. Acetic acid can be converted to acetone on titania. Hence titania is being studied to directly convert acetic acid to mesitylene on a single bed. Esters can be converted to acids and alcohols. Aldehydes can be converted to hydrocarbon on zeolite. Hence a mixture of all these oxygenates is being reacted on titania, Ti/ZSM-5 system. Initially binary pairs of oxygenates were reacted in a batch reactor. The results confirmed the feasibility of using titania for their conversion to hydrocarbon. Then a sample oxygenate mixture was made based on the product mixture formed when syngas is converted to mixed alcohols on a Rhodium catalyst. The oxygenate mixture was tested on titania and considerable hydrocarbon formation was observed. More work is being performed to optimize conversions and yields.

1. Liu, Shetian, Gujar, Amit C., Thomas, Peter, et al., Synthesis of gasoline-range hydrocarbons over Mo/HZSM-5 catalysts. Applied Catalysis A: General 357 (1), 18 (2009).

2. Hu, Jianli, Wang, Yong, Cao, Chunshe, et al., Conversion of biomass-derived syngas to alcohols and C2 oxygenates using supported Rh catalysts in a microchannel reactor. Catalysis Today 120 (1), 90 (2007).