Highly efficient hydrodeoxygenation of bio-oil into bio-fuel by carbon shell defect-rich Co-based heterostructure...

The catalytic hydrodeoxygenation (HDO) of bio-oil, represents a promising route to produce hydrocarbon bio-fuels as potential replacements for traditional fossil fuels. Constructing catalysts with heterostructure interface have emerged as an effective strategy to tune the HDO performance of non-noble metal sites. In this work, defect-rich nitrogen-doped carbon supported Co-based heterostructure materials (Co@NC) were fabricated by low-temperature pyrolysis process of well-defined zeolitic imidazolate framework-67 (ZIF-67) modified with chitosan. The designed Co@NC-480 catalyst exhibited 100 % guaiacol conversion and 94.6 % cyclohexane product selectivity at 250 °C and 3.0 MPa H₂ pressure for 4 h, as well as achieved the conversion of crude bio-oil to hydrocarbon fuel with 69.2 % selectivity. Experiments and characterizations demonstrated that introduction of moderate chitosan induced the construction of Co/NC interface, which facilitated electron transfer between the metal Co sites and defect-rich N-doped carbon support to form synergistic metallic Co and electron-deficient Co sites, promoting the efficient HDO of guaiacol to cyclohexane. Furthermore, combining with in-situ DRIFTS revealed the evolution pathway of cycloalkanes through guaiacol catalytic fast hydrogenation of aromatic ring and rate-determined C-OH hydrolysis of cyclohexanol. In addition, the confine-temperature pyrolysis strategy of metal organic frameworks opens a new pathway toward heterostructure catalyst with high dispersed and small size of metal particle.