Lignocellulosic biomass is a promising renewable feedstock that could replace fossil resources to produce valuable chemicals and biofuels. However, the conversion of lignocellulose requires sophisticated pretreatment processes to efficiently depolymerise and separate its polymeric components (i.e. lignin, cellulose and hemicellulose). In this framework, the mechanocatalytic depolymerisation (MCD) of biomass has emerged as a promising method. Ball-milling of an acid-impregnated substrate generates highly depolymerised, water-soluble products (WSP), which can be further hydrolysed under low severity conditions to provide two isolated streams: depolymerised lignin and C5/6 sugars. Despite these promising results, the mechanisms underlying MCD are poorly understood, and additional product separation and purification methods must be developed to exploit the full potential of MCD on an industrial scale. In this Thesis, kinematic modelling approaches were applied to three different ball mills to estimate the mechanical energy transferred to the substrate during the MCD process. Experimental setups using varied milling parameters revealed crucial correlations between the apparent energy transfer and WSP formation during the processing of α-cellulose and beechwood. The results highlight the fundamental importance of the geometry, working principle and process settings of a ball mill for its effectiveness in momentum transfer. Furthermore, this Thesis investigates the separation of the WSP through adsorption on a benzene-derived microporous organic polymer (MOP). The selective recovery of the adsorbed material by desorbing the polymer with solvents of different polarity in sequence represents an alternative technique to effectively fractionate the WSP according to their molecular weight, elemental composition and lignin content. Finally, this Thesis presents an effective technique to purify the sugar stream produced by the MCD of lignocellulose and subsequent hydrolysis for biotechnological applications. Thereby, the reusable benzene MOP was used to selectively adsorb furfurals and phenolic lignin residues, which have proven as toxic inhibitors for microbial activity, yielding high-quality sugars for ethanol fermentation.