Standard Test Method for Determination of the Unit Cell Dimension of a Faujasite-Type Zeolite
浮石型沸石单孔尺寸测定的标准试验方法
发布日期:
2019-04-01
1.1
本试验方法包括测定具有八面沸石晶体结构的沸石的晶胞尺寸,包括合成沸石
Y
和
十、
沸石及其改性,例如各种阳离子交换形式,以及脱铝、脱阳离子和超稳定形式的
Y
. 这些沸石具有立方对称性,晶胞参数通常在24.2和25.0范围内 Å(2.42和2.50 纳米)。
1.2
样品包括各种形式的沸石制备,以及含有这些沸石的催化剂和吸附剂。
沸石的含量可能低至5 %, 例如在裂化催化剂中。
1.3
本标准并非旨在解决与其使用相关的所有安全问题(如有)。本标准的用户有责任在使用前制定适当的安全、健康和环境实践,并确定监管限制的适用性。
1.4
本国际标准是根据世界贸易组织技术性贸易壁垒(TBT)委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。
====意义和用途======
4.1
沸石
Y
和
十、
特别是对于催化剂和吸附剂应用,是一种主要的制造和商业产品。由这些不同形式的沸石以及粘合剂和其他成分组成的催化剂和吸附剂也同样重要。
Y
-基催化剂用于石油的流化催化裂化(FCC)和加氢裂化,而
十、
-基吸附剂用于干燥、硫化合物去除和空气分离。
4.2
新合成的八面沸石的晶胞尺寸是组成的敏感量度,除其他用途外,它区分了两种合成的八面沸石,
十、
和
Y
. 矩阵的存在性
Y
-由于含有催化剂,无法通过直接元素分析测定沸石骨架组成。
4.3
试验方法的用户应注意,骨架组成和晶胞尺寸之间的相关性特定于沸石的给定阳离子形式。
例如,蒸汽或热处理可能会改变成分和阳离子形式。因此,用户必须确定与含沸石样品相关的相关性。
3.
此外,可以仅使用测试方法来确定单元尺寸,在这种情况下,不需要相关性。
4.4
样品中可能存在其他晶体成分,其衍射图案可能会干扰选定的八面体结构衍射峰。如果有理由怀疑存在此类成分,则应获得完整的衍射仪扫描并进行分析,以选择八面体-
结构峰无干扰。
1.1
This test method covers the determination of the unit cell dimension of zeolites having the faujasite crystal structure, including synthetic
Y
and
X
zeolites, their modifications such as the various cation exchange forms, and the dealuminized, decationated, and ultra stable forms of
Y
. These zeolites have cubic symmetry with a unit cell parameter usually within the limits of 24.2 and 25.0 Å (2.42 and 2.50 nm).
1.2
The samples include zeolite preparation in the various forms, and catalysts and adsorbents containing these zeolites. The zeolite may be present in amounts as low as 5 %, such as in a cracking catalyst.
1.3
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
====== Significance And Use ======
4.1
Zeolites
Y
and
X
, particularly for catalyst and adsorbent applications, are a major article of manufacture and commerce. Catalysts and adsorbents comprising these zeolites in various forms plus binder and other components have likewise become important.
Y
-based catalysts are used for fluid catalytic cracking (FCC) and hydrocracking of petroleum, while
X
-based adsorbents are used for desiccation, sulfur compound removal, and air separation.
4.2
The unit cell dimension of a freshly synthesized faujasite-type zeolite is a sensitive measure of composition which, among other uses, distinguishes between the two synthetic faujasite-type zeolites,
X
and
Y
. The presence of a matrix in a
Y
-containing catalyst precludes determination of the zeolite framework composition by direct elemental analysis.
4.3
Users of the test method should be aware that the correlation between framework composition and unit cell dimension is specific to a given cation form of the zeolite. Steam or thermal treatments, for example, may alter both composition and cation form. The user must therefore determine the correlation that pertains to his zeolite containing samples.
3
In addition, one may use the test method solely to determine the unit cell dimension, in which case no correlation is needed.
4.4
Other crystalline components may be present in the sample whose diffraction pattern may cause interference with the selected faujasite-structure diffraction peaks. If there is reason to suspect the presence of such components, then a full diffractometer scan should be obtained and analyzed to select faujasite-structure peaks free of interference.