煤系高岭土二次煅烧水热合成P型分子筛

Synthesis of P molecular sieve from coal series kaolinite by calcination twice and hydrothermal reaction

以煤系高岭土为原料,采用二次煅烧和水热合成的方法制备了P型分子筛。第一次煅烧的条件是高岭土和氯化铵混合,条件是800℃、2 h,得到含有少量铁离子的偏高岭土;第二步煅烧的条件是向偏高岭土中加入碱,煅烧条件是400℃,2 h。通过单因素实验,考察了SiO2/A12O3、老化时间对晶相的影响,H2O/Na2O对晶化时间的影响,配料煅烧对产率、粒径、Ca2+、Mg2+交换量的影响。确定了反应的最佳条件为:以NaOH作为配料进行二次煅烧,SiO2/A12O3=3,H2O/Na2O=45,无老化步骤。用XRD对产品进行了表征,用化学滴定的方法确定了所合成P型分子筛的Ca2+、Mg2+交换量,结果表明:P型分子筛结晶完好,钙镁离子交换容量大。

P molecular sieve was synthesized from coal series kaolinite by caleinating the kaolinite twice and hydrothermal procedures. The first calcination was carried out by mixing the kaolinite with ammonium chloride at 800 ℃ for 2 hours , the metakaolinite was obtained with less iron ion. Then the alkali was added into the metakaolinite from the first setp, the second calcination condition was 400℃ for 2 hours. The ratio of SiO2/Al2O3 and aging time which effeeted the type of the crystal were determined by the single factor method . At the same time ,the relationship between H2O/ Na2O and the crystal time ,the compound of the material which effeeted the ratio of the output, the particle size and the exchange capacity of Ca^2＋ and Mg^2＋ were studied. The P molecular sieve was obtained under the optimum conditions： SiO2/Al2O3=3, H2O/Na2O= 45, without aging period. The results showed that P molecular sieve presented a well-crystal structure which was eharactered by XRD, large ion exchange capacity of Ca^2＋ and Mg^2＋ which was determined by chemical titration.