Solvent-free solketal production from glycerol promoted by yeast activated carbons

•Yeast biomass waste: a new economically feasible precursor for activated carbon production.•Modified activated carbon from yeast biomass waste with above average catalytic activity in the solvent-free glycerol acetalization reaction with acetone.•High selectivity toward [1,3]dioxolan-4-yl-methanols, well known as solketal, throughout the whole catalytic process.•Surface chemistry stability in consecutive catalytic runs.