The hydrotalcite like compound Cu0.13Mg0.6Al0.27(OH)2(CO3)0.135·xH2O (CuHTlc) are synthesized by coprecipitation method and are characterized by XRD, DTA-TG, BET, TEM and 27Al MAS NMR. The results show that at relatively low calcination temperatures (below 300℃), the layer structure of CuHTlc is retained, although partial dehydroxylation in addition to dehydration occurs. At 500℃, the hydrotalcite structure is destroyed and MgO phase appears,the spinel phase forms with the further increase of calcination temperature. CuHTlc calcined at 500℃ has the highest surface area (193m2·g-1). When CuHTlc are calcined above 500℃, the composition of resusting products is Cu0.13Mg0.6Al0.27O0.135, the equation of thermal decoposition of CuHTlc can be expressed as following:Cu0.13Mg0.6Al0.27(OH)2(CO3)0.135·xH2O→Cu0.13Mg0.6Al0.27O0.135+(1+x)H2O+0.135CO2.%共沉淀法合成了Cu0.13Mg0.6Al0.27(OH)2(CO3)0.135·xH2O类水滑石物质(CuHTlc),采用XRD、DTA-TG、BET、TEM 和27Al MAS NMR 技术对其热分解过程进行了表征.结果表明,在较低焙烧温度时(低于300℃),氢氧根和层间水部分脱除,但水滑石仍保持其层状结构;500℃时,其层状结构被完全破坏,出现氧化镁晶相结构,随着焙烧温度的进一步升高,尖晶石晶相生成.500℃时的焙烧产物具有最大比表面(193m2·g-1).当温度高于500℃,焙烧产物组成可表示为Cu0.13Mg0.6Al0.27O0.135,CuHTlc的热分解过程可表示为:Cu0.13Mg0.6Al0.27(OH)2(CO3)0.135·xH2O→Cu0.13Mg0.6Al0.27O0.135+(1+x)H2O+0.135CO2.
展开▼
