高比表面纳米MgO的制备及其影响因素研究

在溶液中采用不同的原料制备了三种前体MgC2O4?2H2O, 经高温焙烧得到高比表面MgO. 用XRD、BET、TEM和TG-DTA等表征手段对前体及产物MgO进行了表征. 结果表明, 以醋酸镁和草酸为原料制备前体草酸镁并在焙烧过程中消除水汽的影响是得到高比表面MgO的关键. 最优条件下制备的样品经520 ℃焙烧后比表面积高达534 m2?g?1, 晶粒尺寸仅为4～5 nm的MgO粒子堆积成一定程度上长程有序的介孔结构, 并具有十分优良的抗高温烧结性能. 650 ℃和800 ℃焙烧2 h后, 其比表面积仍分别高达229 m2?g?1和134 m2?g?1.

Preparation of Nanometer Magnesia with High Surface Area and Study on the Influencing Factors of the Preparation Process

Three kinds of MgC2O4?2H2O were prepared by precipitation method with different raw materials, and MgO with high surface area was obtained via thermal decomposition of MgC2O4?2H2O in different atmospheres. The precursor MgC2O4?2H2O and as-prepared MgO were characterized by XRD, BET, TEM, and TG-DTA measurements. It was found that using Mg(CH3COO)2?4H2O and H2C2O4?2H2O as the starting materials and calcining the precursor MgC2O4?2H2O in flowing dry gas are key factors to obtain high surface area MgO. The MgO prepared at the optimum condition is composed of nanocrystals with a size about 4~5 nm and forms a wormhole-like porous structure with a specific surface of 534 m2?g?1 after calcining at 520 ℃. In addition, the MgO has good thermal stability, after calcining at 650 ℃ and 800 ℃ for 2 h, its surface area is still 229 m2?g?1 and 134 m2?g?1, respectively.