Safe direct synthesis of H2O2 within the explosion limit of H2 enabled by low-temperature stable bcc-PdCu alloy membrane

Abstract

Pd based membrane provides an inherently safer way to handle flammable mixture of hydrogen and oxygen, as it could selectively isolate hydrogen from other gases. However, due to their susceptibility to hydrogen embrittlement, pure Pd membranes are not suitable for processes at low temperature. To solve this problem, body-centered cubic (bcc)-PdCu alloy membranes were prepared by the combination of electroplating and electroless plating. The hydrogen permeation rate (JH2), N2 leak rate (JN2) and H2/N2 selectivity (αH2/N2) remained stable through 200 h continuous operation in H2 at 298 K and ΔPH2 = 100 kPa. The excellent low-temperature tolerance of bcc-PdCu membranes rendered them ideal materials for the capture and activation of hydrogen during the direct hydrogen peroxide synthesis from hydrogen and oxygen. The reaction could be performed safely within the explosive limit of hydrogen/oxygen by feeding the gases separately from the opposite sides of the membrane with no direct contact. 60 mmol m−2 h−1 formation rate, 40% H2O2 selectivity, and a nearly 100% hydrogen conversion was reached at 298 K, 500 kPa.