Pd–Ag multi-membranes module for hydrogen production by methane auto-thermal reforming

An experimental campaign has been carried out in order to assess the performance of a two-step membrane process in terms of hydrogen production by methane auto-thermal reforming. rmer operating at high temperature (700 °C) has been coupled with a module consisting of an array of 19 Pd–Ag membranes (length 250 mm, diameter 10 mm and wall thickness 0.150 mm) operating at 300–400 °C. The hydrogen produced in the reformer has been selectively separated through the membrane tubes. The capability of the whole system to produce pure hydrogen has been investigated by varying the operating parameters: reformer temperature 580–700 °C, reaction pressure 100–500 kPa, water/methane feed molar ratio from 1.5/1 to 4.5/1 and methane feed flow rate in the range 4.47 × 10−4–1.11 × 10−3 mol s−1. Auto-thermal conditions have been studied by adding air in order to provide oxygen/methane feed molar ratio of 0.1/1, 0.33/1, 0.5/1. mum pure hydrogen flow rate of 1.65 × 10−3 mol s−1 has been collected in the membrane module shell with a reformer temperature of about 700 °C, membrane module temperature of 400 °C, reaction (lumen) pressure of 350 kPa, feed molar ratio methane/water/oxygen of 1/3/0.333 and methane feed flow rate of 1.11 × 10−3 mol s−1. Under these conditions the hydrogen yield measured has been 1.48.