关键词:

固体酸, 铜基催化剂, 氧化羰基化, 甲醇, Fe2O3

Abstract:

Two solid acids SO ^2-₄/ Fe₂O₃ and S₂O^2-₈/Fe₂O₃ were prepared by impregnation of Fe(OH)3 in the solution of H₂SO₄ and (NH₄)2S2O8， and calcination, then mixed with CuCl to obtain Cu^Ⅰ/SO ^2-₄/Fe₂O₃ and Cu^Ⅰ/S₂O^2-₈/Fe2O3 catalysts by heat treatment at high temperature under N₂ flow.They were of more active than the commercial catalysts CuCl for oxidative carbonylation of methanol to dimethyl carbonate (DMC).One of the main factors affecting activity of Cu^I/SO ^2-₄/Fe₂O₃ and Cu^Ⅰ/S₂O^2-₈/Fe₂O₃ catalysts was calcined temperature of SO ^2-₄/ Fe₂O₃ and S₂O^2-₈/Fe₂O₃ solid acid.The results indicated that the catalyst prepared with SO^2-₄/Fe₂O₃ and S₂O^2-₈/Fe₂O₃ solid acid calcined at 550℃ showed the excellent catalytic activity.By the characterization with XRD, NH3-TPD and XPS techniques, it was found that SO^2-₄/Fe₂O₃ and S₂O^2-₈/Fe₂O₃ were solid superacids, and ion-exchange was carried out between Brnsted acid site H⁺ on SO^2-₄/Fe₂O₃ and S₂O^2-₈/Fe₂O₃ with Cu⁺ on CuCl during heat treatment which led to the formation of low chlorine Cu^Ⅰ catalyst.It was also found that structure of these solid acids had no obvious change if the loading of Cu^Ⅰ was at mass ratio of WCuCl/Wcarrier≤1∶2.The more acidity of solid acid carrier,the more Cu^Ⅰ loaded, and the higher activity of catalyst.The acid sites was much more for S₂O₂-₈/Fe₂O₃ calcined at 550℃, and there was of high Cu/Cl of 1.69 and excellent catalytic activity for Cu^Ⅰ/S₂O^2-₈/Fe₂O₃ catalyst.Its conversion of methanol, DMC selectivity and space-time yields were 16.58%, 97.00% and 2.83 g·g^-1·h^-1 respectively.

Key words:

固体酸, 铜基催化剂, 氧化羰基化, 甲醇, Fe2O3