Preparation, Characterization and Application of ZnAlLa-Hydrotalcite-Like Compounds

The preparation of ZnAlLa-hydrotalcite-like compounds ZnAlLa-HTLcs] was studied.ZnAlLa-HTLcs were synthesized by a method of variable pH with the raw materials of Zn(NO3)2.Al(NO3)3, La(NO3)3, and NaOH. The effects of some factors (i.e. pH values, the mole ratio of Al^3- to La^3-.temperature and the period of hydrothermal treatment) on the preparation of HTLcs were discussed systematically. XRD. TG-DTA. FT-IR spectroscopy, and ICP were performed to characterize ZnAlLa-HTLcs samples, and the thermal stability of HTLcs was also discussed. It was shown that unique ZnAlLa-HTLcs with high crystallinity can be prepared, under the conditions of pH=5.5-6.5. n(Zn^2 )/n(Al^3 La^3 )=2 and the atomic ratio of La^3 to Al^3 ranging from 0.07 to 2. hydrothermal treatment at 120℃ for 5 h. When the calcination of the HTLcs is performed at temperatures above 200℃. ZnO phase is detected with Al2O3 and La2O3 spreading on its top. The complex metal oxides derived from ZnAlLa-HTLcs at 500℃ have higher catalytic activity and selectivity than those from ZnAl-HTLcs for the esterification of acetic acid with n-butanol under the same reaction conditions.

Preparation, Characterization and Application of ZnAlLa-Hydrotalcite- Like Compounds

The preparation of ZnAlLa-hydrotalcite-like compounds ZnAlLa-HTLcs] was studied. ZnAlLa-HTLcs were synthesized by a method of variable pH with the raw materials of Zn(NO3)2, A1(NO3)3, La(NO3)3, and NaOH. The effects of some factors (i.e. pH values, the mole ratio of A13+ to La3+, temperature and the period of hydrothermal treatment) on the preparation of HTLcs were discussed systematically. XRD, TG-DTA, FT-IR spectroscopy, and ICP were performed to characterize ZnAlLa-HTLcs samples, and the thermal stability of HTLcs was also discussed. It was shown that unique ZnAlLa-HTLcs with high crystallinity can be prepared, under the conditions of pH=5.5-6.5, n(Zn2+)/n(Al3++La3+)=2 and the atomic ratio of La3+ to A13+ ranging from 0.07 to 2, hydrothermal treatment at 120C for 5 h. When the calcination of the HTLcs is performed at temperatures above 200C, ZnO phase is detected with Al2O3 and La2O3 spreading on its top. The complex metal oxides derived from ZnAlLa-HTLcs at 500C have higher catalytic activity and selectivity than those from ZnAl-HTLcs for the esterification of acetic acid with n-butanol under the same reaction conditions.