Heterogeneous catalysis cannot be easily applied to solids such as cellulose. However, by mechanically grinding the correct catalyst and reactant, it is possible to induce solid–solid catalysis or mechanocatalysis. This process allows a wide range of solids to be effectively utilized as feedstock for commercially relevant compounds. Here we show a set of structural and physical parameters important for the implementation of catalysts in mechanocatalytic processes and their application in the catalytic depolymerization of cellulose. Using the best catalysts, which possess high surface acidities and layered structures, up to 84% of the available cellulose can be converted to water-soluble compounds in a single pass. This approach offers significant advantages over current methods - less waste, insensitivity to feedstock, multiple product pathways, and scalability. It can be easily integrated into existing biorefineries - converting them into multi-feedstock and multi-product facilities. This will expand the use of non-food polysaccharide sources such as switch grass.

Using a mechanically driven Diels–Alder reaction we were able to characterize the chemical energetics of a SPEX 8000M mixer/mill. Our results demonstrate that the conditions produced by this type of mill are similar to those produced when performing the same reaction at 90 °C in solution. Discrete element models and in situ temperature logging were used to analyse the energetics of this system. These models indicate that the yields obtained using a SPEX 8000M mill are best correlated to the velocity of the media and number of non-zero force collisions.

Catalytic hydrogenation is an important process used for the production of everything from foods to fuels. Current heterogeneous implementations of this process utilize metals as the active species. Until recently, catalytic heterogeneous hydrogenation over a metal-free solid was unknown; implementation of such a system would eliminate the health, environmental, and economic concerns associated with metal-based catalysts. Here, we report good hydrogenation rates and yields for a metal-free heterogeneous hydrogenation catalyst as well as its unique hydrogenation mechanism. Catalytic hydrogenation of olefins was achieved over defect-laden h-BN (dh-BN) in a reactor designed to maximize the defects in h-BN sheets. Good yields (>90%) and turnover frequencies (6 × 10^–5–4 × 10^–3) were obtained for the hydrogenation of propene, cyclohexene, 1,1-diphenylethene, (E)- and (Z)-1,2-diphenylethene, octadecene, and benzylideneacetophenone. Temperature-programmed desorption of ethene over processed h-BN indicates the formation of a highly defective structure. Solid-state NMR (SSNMR) measurements of dh-BN with high and low propene surface coverages show four different binding modes. The introduction of defects into h-BN creates regions of electronic deficiency and excess. Density functional theory calculations show that both the alkene and hydrogen-bond order are reduced over four specific defects: boron substitution for nitrogen (B_N), vacancies (V_B and V_N), and Stone–Wales defects. SSNMR and binding-energy calculations show that V_N are most likely the catalytically active sites. This work shows that catalytic sites can be introduced into a material previously thought to be catalytically inactive through the production of defects.