Pine pyrolysis vapors were upgraded at 500°C using ZSM-5 and NiO/ZSM-5 with varying nickel loadings. These catalysts converted raw, oxygenated pine pyrolysis vapors into aromatic hydrocarbons. The effects of nickel loading and pretreatment (reduction in hydrogen) were investigated. Reaction results show that the addition of nickel increases the yield of aromatic hydrocarbons over the course of the reaction while simultaneously increasing the conversion of oxygenates, relative to ZSM-5, and these effects were more pronounced as the nickel loading increased (see Figure 1). In addition, the oxidized and reduced forms of nickel on ZSM-5 (either NiO/ZSM-5 or Ni/ZSM-5) were tested for pyrolysis vapor upgrading and the activity of both catalysts converged with increasing time on stream. These results suggest that the catalysts reach the same active state during catalytic pyrolysis upgrading, regardless of the initial state of the nickel. Characterization of fresh and spent catalysts by NH3 TPD, H2TPR, and XRD corroborate the reaction results and showed that NiO undergoes an in situ reduction to Ni by pyrolysis vapors. This result is significant in that it shows that the active state of the catalyst may be achieved with the need of an activation in hydrogen step – which could lead to a reduction in the complexity and operating costs associated with a biorefinery. The nickel addition to ZSM-5 is was not observed to increase the intrinsic reaction rate for aromatization to produce hydrocarbons, but rather, the increase in activity is attributed to the ability of nickel to mitigate deactivation via coke deposition which results in capping of zeolite micropores.

Biofuel production by catalytic pyrolysis vapor upgrading: Effects of nickel loading and pretreatment on modified ZSM-5

253rd National Meeting (2017)

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