Document Type : Research Paper
Homi Bhabha National Institute, Anushaktinagar, Mumbai – 400094, India
Desalination & Membrane Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, India
Powder Metallurgy Division, Materials Group, Bhabha Atomic Research Centre, Vashi Complex, Navi Mumbai - 400705, India
CSIR-Indian Institute of Petroleum, Dehradun - 248005, India
Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, India
Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, India
Hydro-processing is a crucial step in bio-jet fuel production. The left-over hydrogen in the vent gas from the hydrocracker cannot be recycled back as it contains several impurities like light hydrocarbons & H2S. Here we report the development of composite palladium alloy membranes for the recovery of hydrogen from the simulated bio-jet fuel production environment, which is investigated for the first time. The metal membranes were fabricated on porous stainless steel (PSS) tubes as support. An intermediate alumina layer was coated over support using vacuum-assisted dip coating. The He/Ar gas selectivity of composite support was determined to be 4.92 at 0.05 bar (trans-membrane pressure). A dense thin film (~ 4 µm) of Pd (60 wt.%) - Cu (40 wt.%) metal was coated on composite support by the DC magnetron sputter deposition technique. The membrane was tested in simulated gas having the composition of vent gas stream of hydrocracker, as a preparatory step before application in the actual environment. The permeance of the in-house developed membrane was found to be ~ 1 GPU with a hydrogen recovery of 37 and 54% at 1.5 bar and 2 bar, respectively. The membrane permeance after exposure to a vent gas environment for 24 hours was reduced by ~ 75%. The membrane was regenerated in a mixture of H2 (10%) - He (90%) at 0.2 bar and 250 ˚C for 5 hours, and the flux was restored up to 85% of the flux of the unexposed membrane. The studies have opened up a new domain of application for metal membranes.