Fig. 1

Schematic representation of the assumed biomass geometry and enzymatic hydrolysis mechanism. Only a fraction of the biomass particle, containing all pores accessible to cellulases, is subjected to hydrolysis. Subsequently to their diffusion to the binding sites located at the pore wall, enzymes bound to cellulose fibers and catalyze their depolymerization (surface reaction). The integration volume is given by \({\varvec{d}}{\varvec{V}}={\varvec{r}}{\varvec{d}}{\varvec{r}}{\varvec{d}}\boldsymbol{\varphi }{\varvec{d}}{\varvec{z}}\)