Green production of low-molecular-weight xylooligosaccharides from oil palm empty fruit bunch via integrated enzymatic polymerization and membrane separation for purification

•Hemicellulose hydrolysate containing xylan was produced via continuous hydrothermal treatment on a pilot scale.•Low-molecular-weight XOS was prepared via optimized enzymatic hydrolysis on a pilot scale.•Phenolic compounds were removed via the enzymatic polymerization process.•Phenolic compounds in the XOS were further removed via membrane separation.