Jim Acquaviva¹, Scott D. Hopkins¹, Rajinder P. Singh¹, Rick Kleiner², Matthew K. Keeling³, Paul M. Thoen³, and J. Douglas Way^3
1Pall Corporation, East Hills, NY  11548  USA
²Consultant to the Pall Corporation, Castle Rock, CO  USA
³Department of Chemical Engineering, Colorado School of Mines, Golden, CO  80401  USA

  Abstract

Commercialization of a robust hydrogen selective membrane has the potential to change the chemical industry by replacing and/or enhancing traditional reaction and separation procedures, thereby resulting in sizable savings in energy consumption and capital investment in equipment.  This increased functionality would provide process engineers with a new tool to use for design of energy efficient processes for a variety of hydrogen related applications.

 Palladium and its alloys are permeable to hydrogen and have been widely studied due to their high hydrogen permeability, chemical compatibility with many hydrocarbon containing gas streams, and their theoretically infinite hydrogen selectivity.   Palladium alloys such as Pd₉₅Au₅, Pd₇₇Ag₂₃ and Pd₆₀Cu₄₀ are options for industrial use based on increased tolerance to trace contaminants such as H₂S and increased permeability.

Pall Corporation, a leading manufacturer of inorganic membranes has partnered with Colorado School of Mines to move this promising technology from the lab to industry.  Composite membranes, consisting of a thin Pd alloy film supported on a porous substrate, have been investigated as a means of reducing the membrane cost and improving H₂ flux.  Figure 1 shows that feasibility has been established for producing membrane layers with a thickness between one and two microns.    Membrane quality and durability was demonstrated with H₂/N₂ ideal (pure gas) selectivity over 100,000 and stable fluxes over 1600 hours.  Mixed gas testing showed H2 permeate purities of 99.99%, at hydrogen recoveries of over 70% at 400 °C.

A critical success factor is establishing the market focused definition of a “commercial product”.   This definition is typically represented by product performance claims based on a series of validation testing.  These claims must be supported by robust manufacturing processes and quality controls.  Equally as important is the cost / benefit analysis that goes along with application development needed to establish economic viability of the product offering. 

This paper will detail the challenges that have been met as well as the ones that lay ahead. 

Figure 1. The influence of membrane thickness on the pure hydrogen flux for Pd membranes deposited on Pall AccuSep® substrates at 20 psi and 400 °C.	Figure 2.