(671d) Lattice Distorted Mnco Oxide Materials As Efficient Catalysts for Transfer Hydrogenation of Levulinic Acid Using Formic Acid As H-Donor

Aqueous-phase hydrodeoxygenation of biomass-derived feedstocks to renewable chemicals and fuels is important for sustainable development of chemical industry ^[1]. It is well known that, traditional hydrogenation processes using H₂ are usually conducted under harsh temperatures (>150 ℃) or pressures (>3MPa), which usually aren’t friendly to catalysts and cause huge emission of greenhouse gases. It cannot be ignored that the use of H₂, still derived from fossil fuels, makes biomass conversion costly and unsustainable. In contrast, catalytic transfer hydrogenation (CTH) without external H₂ display both technological and economic advantages, since the reaction is conducted under milder conditions with inexpensive H-donors (alcohols, acids and hydrazine) which result in safe reaction environment, efficient atomic economy and low-cost capital investment ^[2].

Levulinic acid (LA) is a promising platform molecule produced from the hydrolysis of cellulose. It exhibits great potential for the production of various downstream chemicals, which involves LA hydrogenation to γ-valerolactone (GVL) as the key step. CTH of LA using H-donors represents one of the most sustainable routes compared to conventional hydrogenation ^[3]. It is known that inexpensive Mn- and Co-based materials have yet to be reported for CTH of LA using formic acid (FA) as H-donor ^[4].

In this work, we first proposed unique MnCo oxide catalysts for conversion of LA to GVL in FA aqueous medium, which show enhanced stability and activity (80% LA conversion and 80% GVL selectivity, reused at least 5 times). The key finding is that, lattice distortion of MnCo oxides induces electronically coupled MnCoO₃ phase at MnO_x-CoO_x interface leading to catalytic performance enhancement ^[5]. Kinetic analysis confirms an induction period of LA conversion. There exists competitive reactions between LA activation and FA decomposition on catalyst surface. H species accumulated on MnCo catalyst surface are activated first and then react with LA to generate GVL without external H₂.