Bifunctional Catalyst for Phenol Production via Decarboxylation

Current phenol production relies heavily on the cumene process using fossil-derived benzene and propene, which poses environmental and economic challenges. Alternative synthetic routes such as direct alkylation, amination, and lignin depolymerization are either inefficient, require harsh conditions, or suffer from limited selectivity and substrate scope. Recent attempts to decarboxylate hydroxybenzoic acids using Cu-based catalysts or ionic liquids achieved poor yields (<50%). Moreover, integrating decarboxylation with reduction/hydrodeoxygenation in one step remains an unmet challenge. There is a critical need for multifunctional catalysts that perform clean and efficient transformations of bio-based molecules into high-value chemicals under mild conditions.

The patented technology features a multifunctional catalyst composed of bimetallic Fe₍₂₅₎Ru₍₇₅₎ nanoparticles immobilized on a silica support modified with amine-functionalized ionic liquids (IL-NEt₂). The catalyst is synthesized by in situ reduction of iron and ruthenium precursors on a supported ionic liquid phase (SILP), followed by physisorption of IL-NEt₂. This design brings metal and amine sites into close proximity, facilitating synergistic catalysis. The catalyst operates under hydrogen at moderate temperatures (150–175 °C) and pressures (50 bar), converting hydroxy- and aminobenzoic acids to phenols and anilines with >99% selectivity. Tandem reactions are possible, converting substrates with formyl, acyl, or nitro groups into more reduced phenol derivatives. Structural and catalytic integrity is maintained over at least five reuse cycles, with no significant metal leaching or catalyst deactivation. Mechanistic studies confirm the cooperative action of the metallic and basic components during hydrogen activation and CO₂ elimination.

• High product selectivity: >99% yield for phenols and anilines from diverse aromatic acids.
• Multifunctional catalysis: Performs decarboxylation and reduction/hydrodeoxygenation in a single step.
• Sustainable feedstock compatibility: Efficient conversion of lignin-derived and bio-based substrates.
• Catalyst recyclability: Maintains performance over multiple cycles with no structural degradation.
• Operates under mild conditions: Active under moderate temperature and hydrogen pressure without aromatic ring hydrogenation.

• Pharmaceutical synthesis: Production of phenol-derived intermediates for drugs (e.g., anticancer, anti-TB agents).
• Agrochemical manufacturing: Synthesis of fungicide and pesticide building blocks.
• Lignin valorization: Conversion of biomass waste into high-value chemicals.
• Fine and specialty chemicals: Custom phenol and aniline derivatives for dyes and resins.
• Surfactant production: Generation of alkylphenols for nonionic surfactant synthesis.

PCT (WO2024194467A2, 22.03.2024); EP application

Levin, N., Goclik, L., Walschus, H., Antil, N., Bordet, A., & Leitner, W. (2023). Decarboxylation and tandem reduction/decarboxylation pathways to substituted phenols from aromatic carboxylic acids using bimetallic nanoparticles on supported ionic liquid phases as multifunctional catalysts. Journal of the American Chemical Society, 145(41), 22845-22854.