(245e) Continuous Purification of LOHC-Based Hydrogen through Electrochemical Hydrogen Compression

Hydrogen and hydrogen derivatives will play a major role as fuel in heavy-duty mobility and as a feedstock in the chemical industry. The LOHC technology is very promising to store hydrogen in an infrastructure compatible way. Hydrogen is stored via an exothermal hydrogenation of a hydrogen-lean carrier molecule. The hydrogen-rich molecule formed is a hydrocarbon liquid and the infrastructure for fossil fuel can thus be repurposed for LOHCs. When hydrogen is needed, it can be released from the hydrogen-rich molecule in an endothermal dehydrogenation reaction and the original hydrogen-lean molecule is formed back. Hydrogenation and dehydrogenation are catalytic reactions using a supported precious metal catalyst typically conducted in fixed-bed reactors. The released hydrogen has a purity above 99.9 % after the condensation, but does not meet the requirements according to ISO 14687 for utilization in a fuel cell.

Mrusek et al. demonstrated the combination of an electrochemical hydrogen compressor (EHC) with an batch LOHC hydrogen release unit for the first time to efficiently purify and compress the release hydrogen. [1] The critical impurities in the released hydrogen are CO and volatile organic carbons like toluene. The released hydrogen was fed into an EHC, where successful purification on a dry basis and efficient compression was demonstrated. In this contribution we demonstrate the combined continuous dehydrogenation of perhydro-benzyltoluene and the purification of the released hydrogen by EHC to fulfill the requirements of ISO 14687. The operation of the EHC with LOHC-based hydrogen causes an increase in the cell-voltage, which indicates a poisoning of the Pt catalyst at the anode due to CO adsorption and therefore in-situ regeneration strategies like electrooxidation or oxidation with an air bleed were developed.

Reference

[1] Mrusek, S., et al.,International journal of hydrogen energy, 2021. 46(29): p. 15624-15634.