Catalytic Dehydration of Biomass Derived 1-Propanol to Propene over M-ZSM-5 (M = H, V, Cu, or Zn)

The impetus to explore biomass derived chemicals arises from a desire to enable renewable and sustainable commodity chemicals. To this end, we report catalytic production of propene, a building-block molecule, from 1-propanol. We found that zeolite catalysts are quite versatile and can produce propene at or below 230 degrees C with high selectivity. Increasing the reaction temperature above 230 degrees C shifted product selectivity toward C4+ hydrocarbons. Cu-ZSM-5 was found to exhibit a broader temperature window for high propene selectivity and could function at higher 1-propanol space velocities than H-ZSM-5. A series of experiments with 1-propan(ol-D) showed deuterium incorporation in the hydrocarbon product stream including propene suggesting that a hydrocarbon pool type pathway might be operational concurrent with dehydration to produce C4+ hydrocarbons. Diffuse reflectance infrared spectroscopy of 1-propanol and 1-propan(ol-D) over CuZSM-5 in combination with deuterium labeling experiments suggest that deuterium incorporation occurs in two steps. Incorporation of deuterium occurs post dehydration via exchange with the partially deuterated catalyst surface.