Reduction of Levulinic acid to valeric acid anhydride and γ-valerolactone using pyrolyzed spent Zn-C battery electrode material derived ZnMnOx/C catalyst

Hydrochloric acid digested carbon - manganese oxide black powder and partially degraded zinc container material from spent Zn-C battery cells were used to prepare a low-cost ZnMnOₓ/C catalyst. This material exhibited excellent catalytic performance for the hydrogenation of levulinic acid, yielding a mixture of γ-valerolactone (GVL) and valeric acid anhydride (VAA). The Zn and Mn contents of the ZnMnOₓ/C catalyst were determined to be 36 ± 1 and 29 ± 1 wt%, respectively. The complete 100% levulinic acid conversion was achieved under optimized conditions: 13.3 g of ZnMnOₓ/C catalyst per mol of levulinic acid, 5.17 MPa H₂, 190 °C, and an 8 h reaction time; producing a GVL: VAA product ratio of 12: 88. The proportion of valeric acid anhydride increased with increasing reaction temperature, with the highest selectivity again observed at 190 °C after 8 h under 5.17 MPa H₂. Catalyst recyclability tests showed a gradual decline in activity, with evulinic acid conversion decreasing from 100% to 75% after four consecutive reaction cycles.