The role of water on the selective decarbonylation of 5-hydroxymethylfurfural over Pd/Al2O3 catalyst: Experimental and DFT studies

•Highly selective decarbonylation of HMF over Pd/Al2O3 in water-containing system.•The hydrogen bonds between hydroxyl of FOL and water hinder dehydrogenation to form FAL and furan.•Hydrogenolysis reactions mainly follow the metal-acid synergistic mechanism.•The hydrogen bonds between hydroxyl on Al2O3 surface and water decrease the acidity of Pd/Al2O3.•Hydrogenolysis and etherification side reactions were suppressed.