The solvent-free hydrogenation of butyl levulinate to γ-valerolactone and 1,4-pentanediol over skeletal Cu-Al-Zn catalyst

•BL was efficiently converted by solvent-free hydrogenation for the first time.•Skeletal Cu-Al-Zn catalyst was prepared by alkali leaching of Devarda's alloy.•GVL and 1, 4-PDO were obtained with yield of 74.8 and 25.6%, respectively.•The skeletal Cu-Al-Zn catalyst displayed high stability of BL hydrogenation.