Layered double hydroxides (LDHs) are anionic clays with unique physical and chemical properties. In this study, an indirect sol-gel synthesis method was applied to prepare alkaline earth metal–substituted layered double hydroxides of Mg_2-xM_x/Al₁ (M = Ca, Sr, Ba). In the sol-gel processing, metal nitrates Mg(NO₃)₂·6H₂O, Al(NO₃)₃·9H₂O, Ca(NO₃)₂·4H₂O, Sr(NO₃)₂ and Ba(NO₃)₂ dissolved in deionized water were used as starting materials; and citric acid monohydrate and 1,2-ethanediol were used as complexing agents. The mixed metal oxides (MMOs) were obtained after thermal treatment of precursor gels at 650 °C and subsequently reconstructed in water to the LDHs. The synthesis products were characterized using X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). Nitrogen adsorption by the Brunauer, Emmet and Teller (BET) and the Barret method was used to determine the surface area and pore diameter of the synthesized alkaline earth metal–substituted MMO materials. It was demonstrated for the first time that the formation of Mg_2-xM_x/Al₁ (M = Ca, Sr, Ba) LDH from the sol-gel–derived powders depends significantly on the nature and concentration on the alkaline earth metal.

层状双氢氧化物（LDHs）是具有独特物理和化学性质的阴离子粘土。在这项研究中，采用间接溶胶-凝胶合成方法制备了碱土金属取代的Mg _2-x M _x / Al _1的层状双氢氧化物（M = Ca，Sr，Ba）。在溶胶-凝胶法中，金属硝酸盐Mg（NO ₃）₂ ·6H ₂ O，Al（NO ₃）₃ ·9H ₂ O，Ca（NO ₃）₂ ·4H ₂ O，Sr（NO ₃）₂和Ba （NO ₃）₂溶于去离子水作为起始原料。柠檬酸一水合物和1,2-乙二醇用作络合剂。在对前体凝胶进行650°C的热处理后，获得了混合金属氧化物（MMO），随后在水中将其重构为LDH。使用X射线粉末衍射（XRD）分析和扫描电子显微镜（SEM）对合成产物进行表征。Brunauer，Emmet和Teller（BET）和Barret方法通过氮吸附来确定合成的碱土金属取代的MMO材料的表面积和孔径。首次证明了Mg _2-x M _x / Al _1的形成 （M = Ca，Sr，Ba）来自溶胶-凝胶粉末的LDH很大程度上取决于碱土金属的性质和浓度。