Oxidative coupling of furfural with alcohols to 2-alkyl-3-(2-furyl) acroleins using Li-ion battery waste based LiNiaMnbCocOd/graphite catalyst

Carbon number upgrading of bio-furans by coupling with other renewable feedstocks is an attractive approach for producing renewable fuel and polymer feedstocks. In this work, used Li-ion battery waste based low cost catalyst was shown as an alternative to expensive noble metal catalysts for coupling furfural with alcohols to give 2-alkyl-3-(2-furyl) acroleins. The catalyst was prepared by pyrolyzing the black electrode coating from 18650 Li-ion cells in a used laptop battery at 600 °C in air. Highest furfural conversions of 72.6, 83.6, 100.0 and 95.4 % were observed for 1-propanol, 1-butanol, 1-pentanol and 1-hexanol respectively, using 0.6 mmol LiOH/mmol of furfural and using 25 mg/mmol of furfural catalyst loading, 0.345 MPa O₂, 110 °C for 4.0 h. However, recycling of LiNi_aMn_bCo_cO_d/graphite catalyst showed significant loss in catalytic activity in four cycles of reuse. A reaction scheme involving oxidation of alcohols to aldehydes followed by base catalyzed aldol condensation was proposed to explain the coupling to give 2-alkyl-3-(2-furyl) acroleins.