Abstract:
The aging process of copperzincaluminum precursors was studied by XRD, TGDTG and TPR techniques. The catalytic activity of CuO/ZnO/Al2O3 catalyst for methanol synthesis were tested using continues flow type fixedbed reactor. For the precursors prepared at the precipitating condition of pH=8.0 and temperature=80℃, the initial phases of the precipitate was a mixture of copper nitrate hydroxide Cu2(OH)3NO3, georgeite(amorphous Cu2CO3(OH)2) and hydrozincite Zn5 (CO3)2(OH)6. By increasing duration of its aging time, the phase of Cu2(OH)3 NO3first transited to georgeite, then interdiffused with Zn5(CO3)2(OH)6, resulting in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Cu,Zn)5(CO3)2(OH)6. It was found that the composition and structure of the precursors altered obviously after the colour transition point. The research results demonstrate that the BET surface area and the amounts of CuOZnO solidsolution of the catalyst increased as the aging time extending which in turn to influence the catalytic activity of the catalyst.