One‐Step Extreme Delignification to Simultaneously Produce High‐Purity Cellulose and Phenolated Lignin

Current forest product strategies, involving cooking and multistage bleaching processes, primarily focus on producing high-quality (e.g., high brightness) cellulose fibers, generating low-quality lignin that is typically burnt for energy production. Here, a formic acid–phenol–water system (FP) for achieving extreme delignification is developed, simultaneously producing high-purity/brightness cellulose pulp fiber and phenolated lignin directly from lignocellulosic biomass. The strategy allows to establish a competitive reaction mechanism by introducing active phenol to replace lignin fragments and to react preferentially with lignin-reactive intermediates, enhancing the lignin removal rate while avoiding its condensation. The directly produced cellulose pulp with superior purity enables it to be adapted to different application areas, e.g., dissolving pulp for textile. Importantly, the in situ phenolated lignin from FP fractionation possesses high reactivity and can be directly considered as bioadhesive for plywood production. This efficient one-pot fractionation process demonstrates a sustainable pathway for building an economic and environmental biorefinery platform.