<p>The conversion of biomass-derived aldehydes via waste shell-derived catalysts is vital for sustainable chemistry, yet green batch synthesis of such catalysts from raw biomass remains underexplored. This study uses crab shells, a kitchen waste, combined with ZrCl₄ via non-toxic hydrothermal synthesis to scale-prepare Zr-containing polyphenolic biopolymer catalyst (Zr-Ch). Comprehensive characterizations revealed that the robust coordination between Zr⁴⁺ ions and phenolic hydroxyl groups in waste shell resulted in the formation of potent Lewis acid-base pair sites (Zr⁴⁺-O²⁻). The synergistic effect of diverse acid-base sites in Zr-Ch enabled exceptional catalytic efficiency for the Meerwein-Ponndorf-Verley (MPV) reaction of furfural (FF) to furfuryl alcohol (FA) with a remarkably lower activation energy of 22.2 kJ/mol, which greatly reduced the reaction temperature to 100 °C. Consequently, a quantitative yield of FA as high as 94.9% and a selectivity for FA of 98.9% were achieved. This research expanded waste shell applications and illuminated acid-base interaction mechanisms in biomass molecule reduction.</p>