# The Silk Route to Green Catalysis: Silk Fibroin as a Recyclable Ligand for Iron‐Catalyzed Olefin Epoxidation

## TL;DR

Silk fibroin from silkworm cocoons is used as a green, recyclable catalyst for efficiently converting olefins into epoxides under mild conditions.

## Contribution

Introduces silk fibroin as a dual-function, recyclable ligand and support for iron-catalyzed epoxidation under sustainable conditions.

## Key findings

- Silk fibroin efficiently coordinates iron for olefin epoxidation with high yields and low metal loading.
- The SF–iron system is highly recyclable and regenerable, maintaining activity over multiple cycles.
- The method offers a green, scalable alternative to conventional catalytic systems.

## Abstract

A sustainable, efficient, and cost‐effective iron‐catalyzed olefin epoxidation is achieved by coordinating iron ions with silk fibroin (SF), a biocompatible protein derived from Bombyx mori cocoons. Unlike conventional systems based on complex ligands or synthetic supports, SF acts both as a support and as a recyclable ligand, efficiently coordinating iron through a simple aqueous process. The resulting SF–coordinated Iron system [Fe(SF)] promotes epoxidation of a broad range of olefins under mild conditions, with excellent yields and low metal loading. Notably, the system combines high activity with remarkable recyclability, and it can be easily regenerated. This work introduces a green, scalable strategy for iron catalysis, demonstrating the untapped potential of a natural polymer as a renewable ligand in heterogeneous catalysis.

Iron coordinated on silk fibroin from Bombyx mori is easily prepared and catalyzes olefin epoxidation under mild, sustainable conditions with O2. With minimal iron loading, the catalyst is highly recyclable and fully regenerable, offering a green route to heterogeneous catalysis.© 2026 WILEY‐VCH GmbH