Hydrogen separation in low pressure industrial processes using Pd/Cu membranes

BLANCO M. V.; MILIDONI M.; BORZONE E. M.; BARUJ A.; MEYER G. O.

Florianópolis

Congreso; XI Congresso SBPMat; 2012

SBPMAT - Sociedade Brasileira de Pesquisa em Materiais

Palladium and palladium alloy membranes have been known for over 100 years to selectively permeate hydrogen over all other gases. Therefore they are extensively used for hydrogen separation and purification where high hydrogen purity and low flows are needed. Optimum operation point of most commercial devices are a membrane temperature between 300 and 450 C, and differential pressure between feed and product ports of about 10-15 bar.In this work we present the use of a Pd/Cu commercial membrane (423 Series purifier, Hy9 Corporation) to eliminate hydrogen from a tank that contains hydrogen with impurities in a relation of 96:4, and a global pressure of 0.95 bar. The gas is the product of one of the final stages of radioisotope production and impurities are nitrogen, humidity and activated noble gases. Bleed gases (impurities + hydrogen) must return to the tank, so both hydrogen partial pressure but hydrogen to impurities relation will decrease with time during the separation process.As hydrogen partial pressure is much lower than suggested feed pressure we analyze different scenarios using a mechanical compression stage (diaphragm compressor/pump). Based on laboratory characterization of this Pd/Cu membrane with impure hydrogen sources under feed pressure in the range 0-10 bar, we present the conceptual design of a solution involving this device. Simulations are made to evaluate the performance of the different options. Final total pressure in the tank and elapsed time to separate at least 90% of hydrogen in the tank are used to compare the results.