4A沸石合成工艺研究与产物表征

利用正交优选实验研究了硅铝比、钠硅比、水钠比、反应温度和反应时间等5个因素对水热合成4A沸石的影响,在此基础上还研究了超声波辅助水热合成4A沸石,利用XRD、场发射扫描电子显微镜(FESEM)和钙离子交换能力对4A沸石进行了表征。正交优选实验结果表明:硅铝比是影响4A沸石钙离子交换能力的主要因素,其次是钠硅比和反应时间,水钠比和反应温度的影响最小;水热合成4A沸石的最佳工艺为以硅铝物质的量比为1.5、钠硅物质的量比为2.05、水钠物质的量比为150配制硅铝酸钠凝胶,于130℃下晶化5 h。通过水热合成及超声波辅助水热合成的4A沸石的对比表明:一定时间的超声波辅助水热合成更容易得到较高性能的4A沸石。

Study on synthesis and characterization of 4A zeolite

Five factors,SiO2/Al2O3 ratio,Na2O/SiO2 ratio,H2O/Na2O ratio,reaction temperature,and reaction time,influencing hydrothermal synthesis of 4A zeolite were studied by orthogonal experimental design,and ultrasonic-assisted hydrothermal synthesis was studied then.The 4A zeolite samples were characterized by XRD,FESEM,and calcium ions exchange capacity.Orthogonal experimental results showed SiO2/Al2O3 ratio was the major influencing factor of ion exchange capacity of 4A zeolite,followed by Na2O/ SiO2 ratio and reaction time,and the impact of H2O/Na2O ratio and reaction temperature were the least.The optimum process conditions were determined as follows: prepare the sodium aluminosilicate gel according to the conditions of n(SiO2)∶n(Al2O3)=1.5,n(Na2O)∶n(SiO2)=2.05,n(H2O)∶n(Na2O)=150,and crystallize at 130 ℃ for 5 h.Comparisons were made between samples obtained by hydrothermal and ultrasonic-assisted hydro thermal synthesis.Results showed that appropriate ultrasonic treatment was helpful to the synthesis of high performance 4A zeolite.