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Franklin E. Epiepang Xiong Yang Jianbo Li Yingshu Liu Ralph T. Yang 《American Institute of Chemical Engineers》2018,64(2):406-415
The aim of this work was to reduce/minimize Li in Li‐LSX by replacing the 70% Li+ cations in Li‐LSX that are bonded to the interior or inaccessible sites which are not used for adsorption. Thus, mixed‐cation LiCa‐LSX containing minimum lithium were prepared by exchanging small fractions of Li+ into Ca‐LSX, followed by dehydration under mild conditions to avoid migration/equilibration of Li cations. Comparisons of adsorption isotherms of N2/O2 and heats of adsorption for the LiCa‐LSX samples with that for pure‐cation Li‐LSX and Ca‐LSX provided strong evidence that significant amounts of these Li cations indeed remained on the exposed sites (SIII). The mixed‐cation LiCa‐LSX samples were compared against the pure‐cation Ca‐LSX and Li‐LSX based on their performance for oxygen production by PSA, via model simulation. The results showed that the mixed‐cation LiCa‐LSX samples yielded significantly higher O2 product productivities at the same product purity and recovery than their pure‐cation precursor (Ca‐LSX). © 2017 American Institute of Chemical Engineers AIChE J, 64: 406–415, 2018 相似文献
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利用导向剂室温(15~30℃)老化后高温晶化合成低硅X型沸石(LSX),用XRD测定样品晶型.对导向剂作用的研究表明,加入老化5h的导向剂17Na2O·6SiO2·Al2O3·250H2O可抑制LSX样品中的羟基方钠石(HS)杂晶,但没有加快LSX反应体系的晶化速度.对原料配比和反应条件的研究表明,产物对H2O/(Na2O+K2O)摩尔比和Na2O/(Na2O+K2O)摩尔比非常敏感,稍有变化就会引起杂晶的生成;随着室温老化和晶化温度的升高以及时间的延长,样品LSX结晶度增大.室温(25~30℃)老化12h、110℃晶化3h合成的LSX结晶度好、纯度高,Si/Al摩尔比为1.02±0.03. 相似文献
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采用Li-LSX, Ca-LSX为起始物进行离子交换分别制备了Li+、Ca2+混合型LSX, 通过ICP-AES, 7Li MAS NMR, 23Na MAS NMR及静态吸附等检测方法, 考察了起始物不同对离子交换限度, 离子定位与产品吸附性能的影响. 实验结果表明, 以Ca-LSX为起始物进行Li交换得到的Li-Ca-LSX最大交换率为31.5%, 此时吸附性能最优, 氮氧吸附量分别为36.4和5.0mL/g, 选择性系数为12.4, 且节约了Li的用量. 借助NMR结果发现, 对吸附性能有直接影响的Li+, 除公认SIII位置外, 尚有少量SI’亦有较显著作用. 相似文献
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