# Freeze Casting of Microporous Composite Beads Based on a Polymer of Intrinsic Microporosity for Gas Storage Applications

## TL;DR

Researchers developed a new method to create PIM-based composite beads for gas storage, which could improve hydrogen storage efficiency for fuel cell vehicles.

## Contribution

The first demonstration of freeze casting PIM-1 droplets into millimeter-scale beads and creating composite beads with activated carbon filler.

## Key findings

- PIM-based beads showed similar BET surface areas to their particulate form.
- Composite beads with 80 wt% activated carbon achieved 1.6 wt% hydrogen storage at 0.1 MPa and 77 K.
- Maximum predicted hydrogen storage capacity of 8.1 wt% could meet DoE targets for fuel cell vehicles.

## Abstract

Polymers of intrinsic microporosity (PIMs) show potential
for gas
storage and separation applications. However, they are often produced
in fine-scale particulate form which can lead to handling and fouling
issues, for example when inserted inside storage tanks. We provide
the first demonstration of a manufacturing technique to form millimeter
scale PIM-based beads by freeze casting PIM-1 droplets. The PIM-based
beads are shown to exhibit similar Brunauer–Emmett–Teller
(BET) surface areas compared to its original particulate form and
low pressure hydrogen isotherms (to 0.1 MPa) are presented to examine
gas storage behavior. We also demonstrate the production of composite
PIM-1 beads containing up to 80 wt % of activated carbon filler, which
leads to improved surface area for gas storage and separation, generally
following the rule of mixtures. The composite beads can store 1.6
wt % hydrogen at 0.1 MPa and 77 K and are predicted to have a maximum
storage capacity of 8.1 wt %, with potential to meet the Department
of Energy (DoE) targets for light duty fuel cell vehicles.