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Rhodium porphyrin complexes as catalysts for ammonia borane hydrolytic dehydrogenation
Manuel Minnucci1, Ilaria Barlocco1, Laura Prati1
1Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy. gabriele.dicarlo@unimi.it.
Rhodium porphyrins are novel single-site catalysts for ammonia borane (AB) dehydrogenation, producing ultra-pure hydrogen. Anionic TSP-Rh demonstrated superior performance, while heterogeneous TAP-Rh offered stable, reusable catalytic activity.
Area of Science:
- Catalysis
- Materials Science
- Green Chemistry
Background:
- Porphyrin-based materials traditionally support metal nanoparticles.
- Ammonia borane (AB) is a promising hydrogen storage material.
- Efficient catalytic systems are needed for AB hydrolysis.
Purpose of the Study:
- To synthesize and characterize rhodium porphyrins as single-site catalysts.
- To evaluate their efficacy in the hydrolytic dehydrogenation of ammonia borane.
- To compare homogeneous and heterogeneous catalytic performance.
Main Methods:
- Synthesis of rhodium porphyrin complexes with cationic, anionic, and neutral porphyrins.
- Characterization using UV-vis, ATR-FTIR, NMR, and ICP-MS.
- Catalytic testing of ammonia borane hydrolytic dehydrogenation at 303 K and 1 atm.
Main Results:
- All rhodium porphyrins effectively catalyzed AB dehydrogenation.
- Anionic TSP-Rh exhibited the highest efficiency (70.7% H2 yield, TOF 15.72 × 10^6 h^-1).
- Heterogeneous TAP-Rh showed stable performance over seven runs (65.4% H2 yield).
Conclusions:
- Rhodium porphyrins are efficient homogeneous and heterogeneous catalysts for hydrogen production from AB.
- Catalyst stability varies, with ionic complexes showing deactivation.
- Heterogeneous TAP-Rh offers a stable and reusable option for ultra-pure hydrogen generation.
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