Green adipic acid production from biodegradable alginate-based biofilms

Overview

This solution offers an environmentally responsible route to adipic acid, a key industrial monomer used in nylon-66, polyurethanes, plasticizers, and lubricants. The approach starts from alginate-based biodegradable films, which are broken down into C6 sugar monomers (mannuronic and guluronic acids), oxidized into aldaric acids, and then converted into adipic acid through a patented chemo-catalytic dehydroxylation step using a heterogeneous rhenium catalyst. By replacing the traditional nitric acid oxidation pathway, which generates nitrous oxide as a byproduct, this process eliminates hazardous reagents and reduces the environmental footprint of adipic acid production. The same alginate feedstock simultaneously supports the manufacture of biodegradable packaging, creating a dual-value proposition for partners in polymers, specialty chemicals, and sustainable materials.

Technical specifications

Core process steps:

• Biofilm preparation and controlled biodegradation: Alginate-based biocomposite films are degraded up to the first stage, selectively cleaving glycosidic bonds to release C6 monomers.
• Monomer separation and oxidation: Purified C6 monomers are converted to aldaric acids using heterogeneous mono- and bimetallic catalysts on zirconium dioxide supports under oxidative conditions.
• Patented dehydroxylation step: Aldaric acids are selectively converted to adipic acid using a Re/C heterogeneous rhenium catalyst in a three-phase batch reactor.
• Methanol dual role: Methanol acts as both solvent and in-situ hydrogen donor, forming esters that protect terminal carboxylic groups from lactonization while enabling hydrogenation of intermediate double bonds.

Key advantages:

• Catalyst screening across Ni, NiMo, Pt, Rh, Ru, and Re on neutral and acidic supports identified Re/C as uniquely selective for hydroxyl removal.
• Dehydroxylation yields exceed 95%, with target adipic acid yields above 90% in integrated runs.
• Avoids harmful chemicals typical of conventional adipic acid synthesis.

Technology readiness level

Individual process stages, including biofilm biodegradation, sugar oxidation to aldaric acids, and the patented rhenium-catalyzed dehydroxylation, have each been developed and validated at laboratory scale. Catalyst screening, solvent and gas-phase optimization, and yield assessments have been completed for the dehydroxylation step. Future work focuses on integrating the three stages into a single workflow, optimizing reaction conditions for the oxidation step, and scaling the three-phase batch reactor process. The technology is currently at laboratory-to-pilot readiness, suitable for collaborative scale-up, joint development, and sponsored research partnerships aimed at commercial deployment.