混合金属络合物羟基铬铝交联蒙托土的合成

SYNTHESIS OF HYDROXY-Cr-AI CROSS-LINKED MONTMORILLONITES CONTAINING MIXED-METAL COMPLEXES

用取代法和共聚法合成了不向Cr/Al比的混合金属络合物羟基铬铝交联蒙托土,用XRD、DTA考察了其热稳定性,用^(27)Al-NMR、UV、ESR等技术对柱化溶液中铬和铝的状态进行了研究。结果表明,两种方法均合成出结构相近且底面间距d(001)为1.90～2.49nm的羟基铬铝交联蒙托土。发现Cr/Al比对羟基铬铝聚合物的结构、d(001)值、比表面热稳定性均有较大影响;随Cr/Al比的增加,d(001)逐渐增加,热稳定性下降,但在惰性气氛下热稳定性较好(>500℃)。

Hydroxy-Cr-Al cross-linked montmorillonites (Cr-Al-CLM) with various Cr/Al ratios in the pillaring solution were prepared by two methods: substitution and copolymerization. The thermal stabilities of Cr-Al-CLM products were determined by XRD anp DTA. ^(27)Al-NMR and UV spectroscopy were used to monitor the environment of Cr^(3+) and Al^(3+) to determine whether the pillars contain mixed metal complexes. Cr-Al-CLM products prepared by copolymerization have have the same structure as those prepared by substitution and have basal spacing d(001) values between 2.49-1.9nm. The structure of hydroxy-Cr-Al oligocation, d(001) values, surface areas and the thermal stabilities of Cr-Al-CLM products are affected by the Cr/Al ratio in the pillaring solution. The d(001) values of them increase and the thermal stabilities decrease with increasing Cr/Al ratio. Cr-Al-CLM products showed higher thermal stabilities(>500℃)when calcined in inert gas(N_2).