Decomposition of Additive-Free Formic Acid Using a Pd/C Catalyst in Flow: Experimental and CFD Modelling Studies

Sanaa Hafeez,Nikolaos Dimitratos,Alberto Villa,George Manos,Sultan M Al-Salem,Achilleas Constantinou,Felipe Sanchez

doi:10.3390/catal11030341

Abstract

The use of hydrogen as a renewable fuel has gained increasing attention in recent years due to its abundance and efficiency. The decomposition of formic acid for hydrogen production under mild conditions of 30 °C has been investigated using a 5 wt.% Pd/C catalyst and a fixed bed microreactor. Furthermore, a comprehensive heterogeneous computational fluid dynamic (CFD) model has been developed to validate the experimental data. The results showed a very good agreement between the CFD studies and experimental work. Catalyst reusability studies have shown that after 10 reactivation processes, the activity of the catalyst can be restored to offer the same level of activity as the fresh sample of the catalyst. The CFD model was able to simulate the catalyst deactivation based on the production of the poisoning species CO, and a sound validation was obtained with the experimental data. Further studies demonstrated that the conversion of formic acid enhances with increasing temperature and decreasing liquid flow rate. Moreover, the CFD model established that the reaction system was devoid of any internal and external mass transfer limitations. The model developed can be used to successfully predict the decomposition of formic acid in microreactors for potential fuel cell applications.

Highlights

The use of conventional fossil fuels for energy production have led to serious climate and environmental concerns
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Facilitating the desorption of this species could lead to the liberation of active sites which would be available for formic acid to be decomposed in subsequent cycles of the reaction

Summary

Introduction

The use of conventional fossil fuels for energy production have led to serious climate and environmental concerns. This suggests that the loss in activity of the Pd/C catalyst can be attributed to the accumulation of CO during the decomposition of formic acid for hydrogen production reaction. This suggests that, for this specific reaction and reaction conditions, heat transfer effects are eliminated in the packed bed microreactor. The results suggest that after 10 regenerations, the initial activity of the catalyst can be fully restored for a period indicating a very promising catalytic regeneration for the dehydrogenation of formic acid under mild conditions

Catalyst Characterisation

Experimental Set-Up

Modelling of Packed Bed Microreactor

Numerical Procedure

Conclusions