Synthesis And Adsorption Ability For NO_x Of Anion Layered Double Hydroxides Materials

The research on the structure and properties of laminated structure materials has become a hotspot recently. Hydrotalcite is a kind of negative ion clay with typical laminated structure. Its structure is similar with brucite Mg(0H)2, in which Mg2+ could be isomorphously replaced by Al3+ partly. The general formulas Hydrotalcite-like compounds are usually written as [MIIVxMIIIx(OH)2]x+ (An-)x/n mH2O. The ratio of M2+ and M3+ could be adjusted in wide range, which can not only maintain its laminated structure but also adjust its acidity and basicity, even oxidation-reduction nature. So hydrotalcites are widely used for numerous catalysis pursuers.This research work in this paper is mainly about that numerous hydrotalcite-like compounds were synthesized by co-precipitation. The samples were characterized by XRD, IR,TG-DTA; and the adsorption capacity of the samples after calcination at 500 ℃ for nitrogen oxides was measured. At last, optimal preparation condition is decided and some meaning conclusions are drawed.Diatomic metal hydrotalcite-like compounds were synthesized. The results show that the samples had typical layer hydrotalcite structure via characterization. The adsorption capacity of Zn3Al-HTlc for NOX was maximal, and the static saturation adsorption capacity was 1851mg/g.Carbonate pillared hydrotalcite-like compounds ( CuCoAl-HTlcs ) with different Cu/Co/Al molar ratios were synthesized by coprecipitation and characterized by XRD, IR, TG-DTA. The abilities of their adsorption on NOX were also measured. The results showed that the samples with Cu/Co/Al molar ratios of 1 : 1 : 1~1 : 7 : 1 have hydrotalcite structure and layer spacings increased with Co amount increase. The TG-DTA results showed that the materials decomposed in two stages and the thermal stability of the hydrotalcites decreased with increasing Co amount. The adsorption ability of the Co3Al-HTlc for NOX was much better than that of the CuCoAl-HTlcs,the adsorption ability of CuCO3Al-HTIC was better than the other the other CuCoAl-HTlcs. The adsorption capacities of the Co3Al-HTlc and CuCo3Al-HTlc were 1781mg/g and 1286mg/g respectively.The preparation of Mg-Al-hydrotalcite(WP-keggin, WSi-keggin) Mg-Al-Cu-hydrotalcite (WP-keggin, WSi-keggin) was studied. The POM-HTLs was synthesized using ion-exchange by introducing POM (heteropolyanions) into the layer of HTLcs. The POM-HTLcs was synthesized with high crystallization and high-order layers with the layered height of approximate 1.15nm successfully. The absorption ability of samples for NOx was also measured.