Molecular simulation of hydrogen storage and transport in cellulose

ABSTRACT

In this work we describe a computational workflow to model the sorption and transport of molecular hydrogen in cellulose frameworks. The work demonstrates the value of the molecular dynamics code, DL_POLY and Monte Carlo code, DL_MONTE sharing common input formats to enhance the compatibility of the codes, being supported by DL_FIELD. Structures generated using cellulose-builder were processed by DL_FIELD to generate input files for DL_POLY using the OPLS_2005 force field. After relaxation in molecular dynamics, structures were used for GCMC simulations in DL_MONTE before passing back to DL_POLY to evaluate transport properties at different levels of sorption. While no hydrogen sorption was seen in pure crystalline cellulose, increasing separation between layers did allow sorption. When slit-pores were sufficiently wide, interactions with the cellulose led to the volumetric density of adsorbed hydrogen exceeding vacuum density at accessible partial pressures as well as allowing diffusion through the system. These model systems can give useful insight into the behaviour of amorphous cellulose in future simulation and experiment.

KEYWORDS:

• Molecular modelling
• molecular dynamics
• Monte Carlo
• cellulose
• hydrogen storage

Acknowledgments

This research made use of the Balena High Performance Computing Service at the University of Bath and used the Isambard UK National Tier-2 HPC Service (http://gw4.ac.uk/isambard/) operated by GW4 and the UK Met Office, and funded by EPSRC (EP/P020224/1). Data availability statement: The data supporting the findings of this study are openly available at https://doi.org/10.5281/zenodo.2538053.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

MRS and LOY acknowledge funding from the EPSRC for a Ph.D. studentship funding through the EPSRC Centre for Doctorial Training in Sustainable Chemical Technologies, University of Bath (EP/L016354/1). CY acknowledges the CCP5 funding and associated CoSeC support at STFC via EPSRC grant no: EP/M022617/1. TJM acknowledges funding via EPRSC grant nos: EP/K021109/1, EP/L018365/1 and EP/P024807/1.