Tailoring and Visualizing Macropores of the Zeolite Monolith to Reveal the Coke Resistance Performance for Bio-oil Hydrodeoxygenation

Mass transport in conventional microporous zeolite catalysts can be enhanced by introducing secondary mesopores during hydrodeoxygenation (HDO). However, the impact of the macropore architecture with intrinsic mass transfer advantages over mesopores on HDO performance remains elusive. In this study, a macroporous zeolite monolith catalyst without a template and binder was synthesized using a crystal space-confined growth method. This catalyst exhibited a 1.3 times higher macropore volume (0.566 m3/g) than a conventional zeolite catalyst, while the microporous structure was similar. Moreover, the high degree macropore connectivity was directly visualized and quantified with an advanced nanocomputed tomography technique. The macroporous catalyst achieved a higher guaiacol conversion rate of 93% and better coke resistance (3.2 wt % coke) than the conventional zeolite catalyst, which showed a 90% guaiacol conversion rate and 5.6 wt % coke. This improvement was primarily due to faster diffusion rates and an increased number of acid sites in the macropores.