The Role Of Rare Earth Oxides On The Thermal Decomposition Of Ammonium Perchlorate And The Modification And Characterization Of LongNan Bentonite

Various rare earth oxides were synthesized respectively by precipitated withoxalate acid, ammonium bicarbonate as well as glycol sol-gel methods. Theircatalytic effects on the decomposition of ammonium perchlorate (AP) have beenstudied using differential thermal analysis (DTA) technique. It can be seen from theirDTA curves that the addition of rare earth oxides could make the first exothermalpeak of ammonium perchlorate hysteresised and the second exothermal peakadvanced. With the addition amount of rare earth oxide increasing, the twoexothermal peaks of AP come closer and finally merge into one strong peak with agreat increase of decomposition heat. The catalyzing action caused by different rareearth oxides was difference. Two adjacent exothermal peaks with former weak andlater strong were observed in the DTA curves of AP mixed with 5% lighter rare earthoxides Pr₆O₁₁ or Nd₂O₃, one strong peak for middle rare earth oxides Sm₂O₃ orGd₂O₃, and two separated peaks with former strong and later weak for heavier rareearth oxides Er₂O₃ or Yb₂O₃. Difference also existed among the Gd₂O₃ powdersprepared by different methods, which was attributed to the difference of their specificsurface area. The catalytic activity of oxides increased with their specific surface areaincreasing. The effect of rare earth oxides on the thermal decomposition of AP wasexplained by energy band theory. Rare earth oxides can be considered as typicalsemiconductors. It was their electron storing and releasing property that resulted inhysteresising of the first exothermal peak or advancing of the second exothermalpeak.The basic characterristics of Longnan bentonite and its modification sampleswith sulphate acid and rare earth were determined. The results show that the samplesare calcium-based bentonite with high ion exchange capability. The treatment usingsulphate acid or sulphate solution containing rare earth can affect on its adsorption,de-color rate,colloid value,esterification reaction activity and thermal stability. Thepotential applications may be found in the catalysis and adsorption. The esterificationactivity of sample can be increased by acid treatment, particularly in the existing ofrare earth. On the other hand, all the sample possess a potential adsorption ability forthe ammonium ion in solution, and the acid treatment will enhance the adsorptioncapability of ammonium ion due to the increase of specific surface area.