Palladium composite membranes have highly selective permeability to hydrogen due to their special dissolution/diffusion mechanism of hydrogen permeation, and are an ideal material for hydrogen separation in membrane reactors. In order to promote the research and application of palladium composite membranes with high hydrogen permeability and stability, the preparation method of the membranes via electroless plating and its combined with other methods, and different types of the membranes are reviewed in this paper. Electroless plating is the most common preparation method of palladium composite membranes, and the quality of the membranes can be improved by combining with vacuum and continuous flow. Using group ⅤB metals, porous ceramics and stainless steel as the matrix of electroless Pd membranes, the membrane thickness can be reduced, mechanical strength and hydrogen permeability can be improved; The thickness of Pd membranes can be further reduced by adding refractory oxide, zeolite, natural mineral and polymer between Pd membrane and porous matrix, and the thermal and chemical stability can be improved. Compared with pure Pd membrane, Pd-Ag, Pd-Cu, Pd-Au binary alloy membranes and Pd-Au-Ag ternary alloy membrane have no hydrogen embrittlement phenomenon at low temperature, and can improve the hydrogen permeability and sulfur resistance of Pd membranes to a certain degrees. Finally, the future research direction of palladium composite membranes is prospected.
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