Palladium reshapes nickel phosphide to improve selective bio-oil upgrading

Bio-oil made from biomass could provide a renewable source of fuels and chemicals; however, its high oxygen content makes it unstable and lowers its energy value. Removing that oxygen through hydrodeoxygenation can improve fuel quality, yet conventional catalysts may also break carbon-carbon bonds, wasting valuable carbon and reducing selectivity. 

To that end, researchers at Zhejiang University and collaborators developed a palladium-engineered nickel phosphide catalyst, NiPdP. Using anisole and m-cresol as representative bio-oil compounds, the catalyst achieved near-complete conversion and 97.28% selectivity to cyclohexane from anisole at 200 ℃ and 1 MPa hydrogen. It also strongly suppressed unwanted carbon–carbon bond cleavage at higher temperatures.

“The key is not simply adding palladium, but using it to reshape how the nickel phosphide phase forms and how its atomic lattice is distorted,” shares corresponding author Kaige Wang from Zhejiang University. “That combination helps the catalyst remove oxygen efficiently while preserving the carbon framework of the molecules.”

Microscopy showed that palladium promoted the formation of highly dispersed nanocrystals only 3-8 nanometers in size, rather than the much larger agglomerated particles seen in the palladium-free catalyst. “Synchrotron X-ray measurements and other analyses further showed that palladium entered the Ni3P lattice, creating lattice strain and changing the electronic state of nickel,” says Wang. “These coupled structural and electronic effects favor activation of carbon–oxygen bonds while limiting competing carbon–carbon bond scission.”

Notably, the catalyst also showed strong durability. “Across 10 consecutive reuse cycles, no apparent deactivation was observed, and analysis of the spent material showed little structural change,” Wang adds. “Carbon deposition was also reduced compared with the palladium-free catalyst.”

The team’s results provide a design strategy for catalysts that combine activity, selectivity and resistance to sintering. Their next step is to evaluate the approach with real bio-oil and under continuous-flow conditions relevant to practical biorefining.

Contact author details:

Kaige Wang, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; kaigewang@zju.edu.cn.

Funder:

National Key R&D Program of China (Grant No. 2023YFE0111600); National Natural Science Foundation of China (Grant No. 52376213); Fundamental Research Funds for the Central Universities (Grant No. 2022ZFJH004); Zhejiang Provincial Natural Science Foundation of China (Grant No. LGG22E060004).

Conflict of interest:

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

See the article:

Xin Liu, Guijin He, Xianhua Zheng, Qi Ouyang, Xiaopeng Shi, and Kaige Wang, Pd-Engineered Ni3P for Selective Bio-oil Upgrading: Coupled Phase Evolution and Lattice Strain Effects.  Green Chemical Engineering. DOI: https://doi.org/10.1016/j.gce.2026.06.002