Iridium complexes supported on cross-linked polyacrylic acid as release-and-catch catalysts for continuous formic acid dehydrogenation

Abstract

Although homogeneous catalysts outperform heterogenous catalysts for formic acid (FA) dehydrogenation, complicated energy-intensive processes are required for catalyst recovery. Herein, we developed an iridium complex immobilized on cross-linked polyacrylic acid as a “release-and-catch” catalyst. During catalysis, the immobilized iridium complex dissolved in the reaction solution and was subsequently recaptured by the support. The activity of this catalyst for FA dehydrogenation (turnover frequency: 110 000 h⁻¹; turnover number: 2 180 000) was comparable to that of homogeneous catalysts. Furthermore, the catalyst was recycled 10 times with near-perfect recovery in a flow-type reaction. These findings offer a promising approach for advancing formic acid-based hydrogen energy carriers.