亚微米4A分子筛的合成与表征

以云南云天化国际股份有限公司的磷肥副产物硅胶湿样为基础原料,补加铝酸钙,水热法制备亚微米4A分子筛。采用XRD、SEM和FT-IR等分析手段对产品进行了表征。结果表明采用水热法制备的产品结晶度为95%;形状规则、大小均匀、分布范围较窄;粒度较小、粒度?1μm的可达到100%;钙离子交换容量为336 mg CaCO3/g(干基)4A分子筛,白度为95%,完全满足洗涤助剂的要求。

溶胶-水热法制备亚微米4A分子筛

以湿硅胶和铝矾土为原料,采用溶胶-水热法合成了亚微米4A分子筛。采用X射线衍射(XRD)、扫描电镜(SEM)和红外光谱(FT-IR)等分析手段对溶胶-水热法制备的亚微米4A分子筛进行表征,并与常规水热法进行对比。结果表明:采用溶胶-水热法制备的产品结晶度为96%;产品形状规则,大小均匀、单一,呈正态分布且分布范围较窄;产品粒度较小,粒径≤1μm粒子体积分数可达到100%;4A分子筛(干基)钙离子(以碳酸钙计)交换容量为335 mg/g,白度为97%,完全满足洗涤助剂的要求。

溶胶-水热法制备亚微米4A分子筛

以硅胶湿样和铝矾土为原料,利用溶胶-水热法合成了亚微米4A分子筛,并采用XRD、SEM和FT-IR等分析手段与常规水热法合成的4A分子筛进行了对比。结果表明,采用溶胶-水热法制备的产品,结晶度为96%,形状规则、大小均匀、呈正态分布且分布范围较窄;粒度小于等于1μm的可达到100%;钙离子交换容量为335mgCa-CO3/g(干基)4A分子筛,白度为97%,完全满足洗涤助剂的要求。

利用磷肥副产物硅渣制备亚微米4A分子筛

以磷肥副产物硅渣制备的硅胶湿样和氢氧化铝为原料,溶胶-水热法合成了亚微米4A分子筛,采用XRD、SEM和FT-IR等分析手段进行了表征.结果表明采用硅胶湿样制备的产品形状规则、大小均匀;干基分子筛相对于CaCO3的钙离子交换容量为340 mg/g,白度为95%,与常规水热合成法制备的产品相比,其粒度较小、分布范围较窄,钙离子交换容量有很大提高.

团聚对亚微米5A分子筛粒度分析的影响

为了考察小晶粒分子筛团聚对亚微米级5A分子筛粒度分布结果的影响以及适宜的测定条件,实验以水为分散介质,六偏磷酸钠为分散剂,在超声波辅助作用下,用电位/粒度分析仪测定研究了试样浓度、分散剂用量和超声时间对亚微米级5A分子筛分散性的影响。结果表明,当分子筛含量大于5 g/L时,晶粒团聚现象严重,粒度分布呈现单峰（假象）,导致粒度测量结果偏大;加入少量（0.005~0.195 g/L）的六偏磷酸钠,有缓解晶粒团聚作用,可将较大团聚粒子（大于2.8μm）分散为较小粒子（1.3μm左右）,少量团聚粒子分散成单个晶粒,可测得较小晶粒粒径;超声作用可使较大团聚粒子（0.85~2.80μm）分布峰强度降低,相对较小粒子（0.30~0.85μm）分布峰强度增加。超声时间不宜太长,否则将加剧粒子间团聚,使得测定粒径偏大。当试样中5A分子筛含量为5 g/L,六偏磷酸钠浓度0.195 g/L、超声时间4 min条件下,测得5A分子筛试样粒径分布0.25~0.80μm,峰顶对应粒径为0.473μm,中位径（d50）为0.784μm,与电镜分析结果一致,说明是较为准确的粒度分析方法。

纳米分子筛ZSM-5的热稳定性研究

Nanosized ZSM 5 zeolite was synthesized by hydrothermal method and characterized by XRD and TEM techniques. The specific heat of the nanosized ZSM 5 zeolite was measured in the temperature range from 79 to 370 K, and its enhancement in specific heat was observed as compared with the corresponding microsized zeolite, indicating that the nanosized ZSM 5 zeolite possesses higher surface activity. The thermostability of the samples was determined by differential scanning calorimetric (DSC) and thermogravimetric (TG) techniques. The DSC results showed that, for the nanosized ZSM 5, a broad exothermic peak is observed from 1?300 K; for the microsized ZSM 5, the corresponding exothermic peak begins at 1?400 K, and a distinct phase transition can be observed at 1?620 K. The TG results showed that, for the nanozised ZSM 5, the maximum mass loss ratio is 6 9%, and two mass loss stages can be observed in the temperature ranges of 298～663 K and 923～ 1?273 K, respectively; for the microsized ZSM 5, the maximum mass loss ratio is 6 5% and it is more stable than the nanosized ZSM 5.

碱金属盐对ZSM-5分子筛晶化的影响

Effect of different alkali metal salts on the crystal size and the crystallization rate of ZSM 5 zeolite was detailedly investigated in this paper. The samples prepared by adding the different alkali metal salts were characterized by using XRD, TEM, TG DSC, BET and IR techniques. The XRD results showed that, for the nanosized ZSM 5 zeolite, the characteristic peaks broadened on the XRD patterns in comparison with the microsized ZSM 5 zeolite. The SEM results verified that the crystal size of zeolites prepared by adding different alkali metal salts had different results, and adding NaCl, NaC2H3O2 and KCl showed the better effect of reducing crystal size, which are about of 40～ 60nm size. The crystallization curve of adding the different alkali metal salts suggested that the crystallization rate was significantly affected by the anions in the alkali metal salt besides the cations. Moreover, the crystal size likewise depended on the anion in the alkali metal salt. In addition, the BET results suggested that the nanosized ZSM 5 zeolite possessed a larger outer surface area in comparison with the microsized ZSM 5 zeolite. The thermostability of the samples was determined by TG DSC technique, indicating that the nanosized ZSM 5 zeolite had a poor thermostability as compared with the microsized ZSM 5 zeolite. The possible difference of the samples with different crystal sizes on IR spectra was also given.

ZSM-5分子筛水热合成条件的实验研究

ZSM-5分子筛是一种孔道结构独特的硅铝酸盐晶体材料,在改善催化裂化汽油质量和提高乙烯、丙烯等低碳烯烃收率方面有重要应用。利用水热合成方法制备出亚微米级ZSM-5分子筛,并研究了水热合成条件对亚微米级ZSM-5分子筛结构特征和物化性能的影响。结果表明:在模板剂用量为25%、晶化温度为185℃、晶化时间为48 h、合成体系碱度为0.10~0.12、原料硅铝比为100的条件下,可以获得结晶度较高、晶体形貌规整、孔结构性质良好的亚微米级ZSM-5分子筛。