摘要
采用预处理法二次合成ＦｅＹ沸石。并用ＸＲＤ．ＩＲ，ＥＳＲ，ＭＢＳ等手段对样品进行表征．结果表明，经（ＮＨ４）２ＳｉＦ６预处理的样品，有更多的Ｆｅ进入沸石骨架脱铝位．进入排石骨架位的Ｆｅ，以四面体或畸变四面体配位形式存在，且不易还原成低价Ｆｅ．由于Ｆｅ进入怫石骨架，样品的晶胞参数增大，骨架红外反对称和对称伸缩振动频率向低波数位移，而未经（ＮＨ４）２ＳｉＦ６预处理的样品，Ｆｅ只能有限地取代骨架位的铝，且骨架结构不发生变化．
eY zeolites were prepared from NH4NaY which was pretreated with(NH4)2SiF6 aqueous solution, then treated with NH4F and Fe(NO3)3 solution at 363 K in buffer solution (pH=4. 0) for 2-4 hours, filtered, washed anddried at 383 K, the above process was repeated once more, the product wasfinally calcined in air at 773 K for 4 hours. The secondary synthetic sampleswere characterized with XRD, IR, ESR, MBS and XPS techniques. The results showed that more iron ions were inserted into the frameWork of zeolitewhen the sample was pretreated with (NH4)2SiF6 aqueous solution, and samples maintained complete pore volume and adsorption ability. The amount ofiron ions inserted into the framework of samples as tetrahedral coordinatedform increases with the increase of treatment time with Fe salt solution. Theiron ions in framework of zeolite are stable and not easily reduced to Fe(Ⅱ)in certain condition. The insertion of Fe into the zeolite leads to an increasein unit cell parameter, and a red shift of the asymmetric and symmetricstretch frequency, while for the samples untreated with (NH4)2SiF6 which framework structure was unchanged.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
1996年第2期157-161,共5页
基金
国家自然科学基金
关键词
二次合成
穆斯堡尔谱
顺磁共振
分子筛
secondary synthesis, FeY zeolite, Mossbauer spectra,electronparamagnetic resonance,characterization
