On configuration of exchanged La3+ on ZSM-5: A theoretical approach to the improvement in hydrothermal stability of La-modified ZSM-5 zeolite

Density functional calculations have been employed to investigate the locating and binding of lanthanum cation, i.e., La(OH)(2)(+), on HZSM-5 zeolite. Through geometry optimization, it was determined that lanthanum ions are favorably accommodated in the two 6-T rings of the straight channels (Clusters 1 and 2, see Sec. III A for details). Cluster 1 was found to exist in prior to Cluster 2 due to the preference of Al substitution in the T11 site (Cluster 1) rather than in the T8 site (Cluster 2). Geometry-optimization of Cluster 1 containing another two lanthanide ions Nd3+ and Yb3+ was also carried out and it was found that a monotonic decrease in Ln-O bond length will take place as the atomic number increases, conforming well to the rule of lanthanide contraction. Some of the optimized parameters are comparable to the corresponding experimental values in Y zeolite, which confirms that the optimized configurations are acceptable. The average frequencies of hydroxyls attached to La3+ or Yb3+ in Cluster 1 fall at 3609.16 and 3579.76 cm(-1), respectively, with the gap of these two frequencies close to that in the sodalite cage of Y zeolite. Compared to H-form zeolite, the charges on both Al and O atoms in Ln-ZSM-5 zeolite show an obvious increase, which will undoubtedly lead to a stronger mutual interaction and hence enhance the stability of the [AlO4](-) anion. Moreover, the Ln(OH)(2)(+) seem to have thickened the zeolite framework, which can effectively retard the process of dealumination. Through the evaluation of the possibility for dimer formation, it turned out that when the exchange degree arrived to approximately 0.28, lanthanum monomers began to aggregate into dimers, and were completely converted into dimers when the exchange degree approached 0.60. (C) 2003 American Institute of Physics.

小晶粒含锆ZSM-5分子筛催化剂及其制备方法

一种小晶粒含锆ZSM-5分子筛催化剂的百分重量组成为SiO2:Al2O3:NaO2:锆＝70-95:1-4:1-2:0.05-3，平均晶粒度为0.2-0.5μm总酸量为0.8-1.1毫摩尔/克分子筛，其平均晶粒度为0.2-0.5μm。本发明具有由合成气经甲醇/二甲醚制汽油反应中，甲醇/二甲醚转化率100％，汽油馏分(C5↑[+])选择性高，且产物油品烯烃含量<10％，更具有环保性，且催化剂抗积碳性能强，单程寿命可达1000小时以上的。

一种快速合成含锆原子ZSM-5分子筛的方法

一种快速合成含锆原子ＺＳＭ－５分子筛的方法是将硅源、钠盐和去离子水配制成Ａ溶液；将铝源、酸和去离子水按摩尔比为配制成Ｂ溶液；将锆源、去离子水配制成Ｃ溶液，在剧烈搅拌下，将Ｂ溶液滴加到Ａ溶液中，然后加入有机模板剂，再加入溶液Ｃ，搅拌使其混合均匀，老化、晶化、固液分离，对滤饼干燥、焙烧２得到分子筛原粉。本发明具有合成出含锆原子ＺＳＭ－５分子筛的结晶度（９０％＞）。合成周期短，晶化时间少的优点。

一种快速合成强酸型ZSM-5分子筛的方法

一种快速合成强酸型ＺＳＭ－５分子筛的方法是按一定比例将硅源与模板剂、去离子水总量的一半配置成Ａ溶液，铝源、无机酸与另一半去离子水配置成均匀的Ｂ溶液，将Ｂ溶液滴加至Ａ溶液中，制成导向剂；再按一定比例将硅源与模板剂、去离子水总量的一半配置成Ｃ溶液，铝源、无机酸与另一半去离子水配置成Ｄ溶液，Ｄ溶液滴加入Ｃ溶液，最后再加入占总体积５－１０％的导向剂，得到强酸型ＺＳＭ－５分子筛；本发明具有合成时间短，酸性强的优点。

导向剂法快速合成ZSM-5分子筛的方法

一种导向剂快读合成小晶粒ZSM-5分子筛的方法，主要包括导向剂制备、分子筛合成两步。第一步导向剂制备首先根据配料比将硅源与无离子水制成Ａ溶液后将模板剂加入，在搅拌下再将由无机酸碱调节适当碱度的铝源滴入均匀反应，按趁虚升温完成后，将合成液体中接近透明的部分分离出即为导向剂。分子筛的合成过程同导向剂相同，只是将原料配比中的有机胺模板剂由导向剂取代，晶化过程需６５－７５小时即可完成，得到平均粒径0.1μm的ZSM5分子筛。本发明制备简单，合成周期短。

In situ preparation of Ir/ZSM-5/cordierite honeycombs and their application for NOx abatement

ZSM-5 zeolites were synthesized in situ onto cordierite honeycombs by vapor phase transport (VPT) for the first time. The as-synthesized ZSM-5/cordierite honeycombs were impregnated with IrCl3 and tested for NOx reduction with a simulated exhaust gas as the reducing agent. Under the conditions of excess oxygen, the Ir/ZSM-S/cordierite monolith catalyst exhibited NO reduction of 73% at a temperature of 573 K and a space velocity of 20,000 h(-1).

Enhanced activity of an In-Fe2O3/H-ZSM-5 catalyst for NO reduction with methane

Selective reduction of NO by CH4 on an In-Fe2O3/H-ZSM-5 catalyst was investigated in the presence of excess oxygen. Compared with In/H-ZSM-5, the In-Fe2O3/H-ZSM-5 catalyst with high Fe2O3 contents showed higher activity in a wide range of reaction temperatures. It was found that the addition of Fe2O3 yielded a promotion effect on CH4 activation. The influence of water vapor on NO conversion was also investigated. The activity of the In/H-ZSM-5 catalyst has been found to be strongly inhibited by water vapor, while the In-Fe2O3/H-ZSM-5 catalyst remained fairly active in the presence of 3.3% steam. (C) 2000 Elsevier Science B.V. All rights reserved.