Cu-Al spinel as a sustained release catalyst for H₂ production from methanol steam reforming:Effects of different copper sources

Cu-Al spinel catalysts were synthesized by the solid-state reaction method using pseudo-boehmite as the Al source and hydroxides, acetates and nitrates of copper as the Cu source. Several techniques such as TG-MS, XRD, H₂-TPR, BET and XANES were employed for the exploration of the synthetic process, phase composition, reduction behaviors and surface structure of the catalysts. Moreover, the catalytic properties for methanol steam reforming (MSR) of these catalysts were evaluated. The obtained results showed that spinel solid solution can be successfully synthesized with the three different Cu sources. The synthesized spinels showed little difference in crystalline size, but their specific surface area (25.4-65.9 m²/g), pore volume (0.213-0.434 cm³/g), surface structure (distribution of Cu) and reduction properties were quite different, which led to different catalytic behavior and performance. During the methanol steam reforming reaction, active Cu species can be released from Cu-Al spinel structure. The catalyst synthesized from copper(Ⅱ) hydroxide shows excellent catalytic performance for MSR as it generates the smallest Cu particles (6.6 nm).