Development and performance evaluation of a palladium–platinum bimetallic-catalyst-based hydrogen eliminator for fuel cell exhaust

Existing hydrogen-elimination technologies suffer from low catalytic efficiency and slow response speed, as well as poor structural integration, which limit their application in fuel cell systems. The high leakage propensity, low ignition energy, and wide combustion range of hydrogen pose critical safety risks that constrain the scalability of hydrogen energy. To address these challenges and achieve high catalytic performance, rapid response, and lightweight, modular integration, this study develops a novel palladium−platinum (Pd–Pt) bimetallic-catalyst-based hydrogen eliminator. By optimizing the catalyst formulation and structural design, the device enhances hydrogen recombination efficiency and operational safety for vehicular and distributed energy systems.

The hydrogen eliminator was designed using a Pd–Pt bimetallic catalyst supported on an integrated system comprising a honeycomb ceramic carrier and catalyst particles to maximize catalytic activity and gas-flow efficiency. The catalyst employs an alumina (Al₂O₃) framework with Pd–Pt nanoparticles at a loading of 300 g/m³, integrated into a 400-mesh porous honeycomb carrier (outer diameter: 80 mm; height: 2 cm). Spherical catalyst particles (diameter: 5.0 ± 0.1 mm) were packed between the honeycomb layers, forming a uniform pore network that minimizes flow resistance and enhances contact efficiency. The eliminator shell, constructed from 45 steel, features a three-segment modular design with flared inlet and outlet channels and fluororubber seals to ensure airtightness. Performance evaluation was conducted on a custom test platform across gas-flow rates and hydrogen concentrations of 100–400 SLPM and 1%–4%, respectively. Real-time monitoring of inlet and outlet hydrogen concentrations and reaction temperatures enabled calculation of the elimination efficiency using X = (H₂_in–H₂_out) / H₂_in × 100%. Nine test conditions were evaluated, covering various flow-rate and concentration combinations. Each test was conducted for 10 minutes to assess steady-state response time, elimination efficiency, and temperature variation.

Experimental results revealed the following: at 100 SLPM, hydrogen-elimination efficiencies reached 93%, 90%, and 88% for hydrogen concentrations of 1%, 2%, and 4%, respectively, with a steady-state response time of approximately 160 s; at 200 SLPM, elimination efficiencies remained within 1% of those recorded at 100 SLPM, although the response time increased to approximately 200 s; at 400 SLPM, elimination efficiencies remained consistent, whereas the response time increased to approximately 300 s, indicating that higher gas-flow rates prolonged the response time without significantly affecting steady-state efficiency; thermal analysis at 200 SLPM revealed steady-state temperatures of 70 ℃, 90 ℃, and 110 ℃ for hydrogen concentrations of 1%, 2%, and 4%, respectively, highlighting the influence of hydrogen concentration on exothermic heat release. The system demonstrated robust catalytic stability and adaptability, with the modular design reducing noble metal loading and enhancing integration flexibility. Furthermore, flow-resistance and pressure-drop tests confirmed the enhanced hydrodynamic efficiency of the structure.

Pd–Pt bimetallic catalysts were integrated with a honeycomb ceramic carrier to achieve hydrogen-elimination efficiencies and response times of 88%–93% and 160–300 s, respectively, effectively meeting the dynamic requirements of fuel cell systems. The modular design and optimized flow channels reduced manufacturing costs, flow resistance, and maintenance complexity, significantly enhancing system integration and scalability. The experimental results elucidate the synergistic effects of gas-flow rate and hydrogen concentration on response time and thermal behavior, providing critical data for engineering scale-up and operational optimization. This design provides a reliable solution for safe hydrogen management in vehicular and distributed energy systems, ultimately supporting the broader adoption of hydrogen fuel cells and sustainable energy transitions.