Ethanol as a Liquid Organic Hydrogen Carrier for Seasonal Microgrid Application: Catalysis, Theory, and Engineering Feasibility

Abstract

In this work, we describe the benefits and challenges of a green approach to seasonal energy storage using ethanol as a liquid organic hydrogen carrier (LOHC). We evaluate the cycling efficiency of hydrogen release from ethanol (EtOH) to form ethyl acetate (EtOAc) as the spent LOHC and the subsequent regeneration of EtOH from EtOAc catalyzed by a single molecular catalyst, Ru-MACHO, at a moderate pressure of H 2 , mild reaction temperature, and high selectivity. From experimental and computational studies, we were able to minimize catalyst deactivation, regenerate the active catalyst post reactions, and establish the energy profile of the deactivation pathway relative to the on-cycle pathway catalyzed by Ru-MACHO. Based upon these findings, we performed a reactor design analysis to determine the footprint of an EtOH-based storage system to provide 85 MWh of energy by storing 5 metric tons (MT) of H 2 . We conclude that the heating and cooling required to maintain H 2 partial pressure present a significant engineering challenge for widespread deployment of this system.

1,4-Butanediol as a Hydrogen Carrier: Liquid- versus Gas-Phase Dehydrogenation

“…6−10 In contrast, the hydrogenation of the aromatic −C�C− double bond is primarily confined to heterogeneous catalysts at higher temperatures and H 2 pressures, 11 which can limit the coupling of existing electrolyzer technology to provide suitable H 2 pressure. Extending beyond the aforementioned oxygenates, our studies on ethanol 12 suggest a closer, systematic examination of 1,4-butanediol (BDO) 13,14 as an LOHC candidate. BDO undergoes similar chemical transformations to that of ethanol with similar thermodynamic considerations along with high conversion and high product selectivity (Scheme 1).…”

“…Extending beyond the aforementioned oxygenates, our studies on ethanol suggest a closer, systematic examination of 1,4-butanediol (BDO) , as an LOHC candidate. BDO undergoes similar chemical transformations to that of ethanol with similar thermodynamic considerations along with high conversion and high product selectivity (Scheme ).…”

ChemSpaX: exploration of chemical space by automated functionalization of molecular scaffold

“…TMCs are oen used as bio-inspired homogeneous catalysts which account for over 15% of all industrial catalytic processes and enable key catalytic transformations such as for pharmaceuticals, ne chemicals, and energy applications. [25][26][27][28][29][30][31][32] Recent studies have revealed the promise of data-driven quantum chemical methods to understand structure-function relations in TMCs. [33][34][35][36][37][38] Availability of structure-property data from QM calculations and/or experiments is central to the success of data-driven chemical approaches.…”

The Ethanol–Ethyl Acetate System as a Biogenic Hydrogen Carrier

“…In previous work, an analysis of the DHC of ethanol to produce hydrogen and ethyl acetate was performed in the liquid phase using a homogeneous catalyst. [ 9 ] A challenge identified in this study was a poor overall energy efficiency, which arose from the high heating and cooling requirements associated with the reflux of ethanol and ethyl acetate. To address this, the current work presents a thermodynamic analysis of the ethanol–ethyl acetate storage cycle in the gas phase where reflux can be avoided.…”