Improved Activity for Cellulose Conversion to Levulinic Acid through Hierarchization of ETS-10 Zeolite

A hierarchically porous ETS-10-supported highly dispersed Ni catalyst was designed to selectively catalyze the conversion of cellulose to levulinic acid under mild reaction conditions. Full conversion of cellulose and remarkably high yield (91.0%) of levulinic acid are achieved due to the synergistic effect of the unique porous structures and Lewis acid sites in the presence of a hydrogen atmosphere. Moderate Lewis acidic centers of the heterogeneous catalyst are revealed to play a positive role in activating the reaction substrates and intermediates, resulting in prominently catalytic activity. Meanwhile, hierarchical pores centered at 16 nm in ETS-10 benefit the mass transfer and therefore further enhance its catalytic performance. Also, during the process of levulinic acid formation, introduction of hydrogen is responsible for converting cellulose thoroughly and keeping the metal Ni from oxidization by the oxy-compounds, which is distinctive from the widely reported pathway dominated only by cellulose hydrolysis.