(255a) Methane Steam Reforming in a Pd Membrane Reactor

Methane Steam Reforming in a PdPt
Membrane Reactor

Stephen N. Paglieri¹, Hani Abu El Hawa²,  Aadesh
X. Harale³,  J. Douglas Way²

¹TDA Research, Inc., Wheat Ridge,
CO 80033-1916, USA

²Department
of Chemical & Biological Engineering, Colorado School of Mines, Golden, CO
80401, USA

³Saudi Arabian
Oil Company, Dhahran, 31311, KSA

Competitively
priced, widely available hydrogen is crucial for the transition to a hydrogen
economy. The distributed production of hydrogen from abundant, domestic natural
gas resources by methane steam reforming (MSR) currently requires very high
temperature catalytic reactors coupled with bulky purification equipment.
Demonstrable gains in efficiency for MSR in a membrane reactor can be obtained by
the withdrawal of product hydrogen, which enables operation at much lower
temperatures instead of the 750-900 °C that is required in conventional MSR
reactors.

Thin
film Pd and PdPt membranes (~5 µm thick)[1] supported on porous yttria-stabilized-zirconia/stainless
steel substrates (ZrOD AccuSep, Pall Corp.) were used to carry out MSR over a commercial
Ni-based reforming catalyst at temperatures up to 600 °C and pressures up to 2.9
MPa. Methane conversion was significantly higher than the thermodynamic
equilibrium predicted for the feed composition; >90% conversion was 
obtained at 600 °C, a steam-to-carbon ratio (H₂O/CH₄) of
5 and a gas-hourly space velocity (GHSV) of 360 h^-1 when the
permeate hydrogen was evacuated, as shown in Fig. 1. For comparison, the
equilibrium conversions at these conditions are <20% . The effect of
parameters such as space velocity, steam-to-carbon ratio, membrane hydrogen
permeance, temperature and pressure on methane conversion and hydrogen recovery
will be discussed.

Reference

1.         Lewis, A.E., et al.,
Pd?Pt/YSZ composite membranes for hydrogen separation from synthetic water?gas
shift streams. J. Membr. Sci., 2013. 437: p. 257-264.