Chemistry of inorganic compounds – Zeolite
Patent
1996-07-09
1997-04-01
Bell, Mark L.
Chemistry of inorganic compounds
Zeolite
4233282, C01B 3902
Patent
active
056163100
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/EP94/03390, filed Oct. 13, 1994.
FIELD OF THE INVENTION
The invention describes the preparation of alkali metal aluminosilicates, in particular crystalline aluminosilicates having the P-structure. These materials are of value as a component in detergent formulations in which they remove calcium and magnesium hardness ions by ion exchange. They also have other properties which provide additional benefits when used in detergent formulations. These aluminosilicates will be referred to as zeolite P in this description.
BACKGROUND OF THE INVENTION
While the utility of zeolite P in detergent formulations has been acknowledged, for example in European Patent Application 0384070 (Unilever), they must be manufactured by a commercially effective process in order to become available on the market place. Thus, while the properties of a material may make it a useful commercial commodity, its manufacture has to be optimised for large scale production.
The zeolite P class includes a series of synthetic zeolite phases which may be in cubic configuration (also termed B or P.sub.c) or tetragonal configuration (also termed P.sub.1) but is not limited to these forms. The structure and characteristics of the zeolite P class are given in "Zeolite Molecular Sieves" of Donald W. Breck (published 1974 and 1984 by Robert E. Krieger of Florida USA). The zeolite P class has the typical oxide formula:
The present invention provides a process for preparing crystalline P-zeolites having Si:Al ratios from 0.9 to 1.33, preferably ratios of 1.15:1 and below and more preferably 1.07:1 and below.
M is an n-valent cation which for this invention is an alkali-metal, that is lithium, potassium, sodium, caesium or rubidium with sodium and potassium being preferred and sodium being the cation normally used in commercial processes.
Thus sodium may be present as the major cation with another alkali metal present in a minor proportion to provide a specific benefit.
The process of the present invention allows the production of P-zeolite with the above defined ratios at economic yield. During the formation of the crystalline zeolite the reacted medium passes through a gel stage.
TESTS AND METHODS
The crystallinity measurements were made in the following manner.
Firstly x-ray diffraction patterns were measured for a pure phase reference sample of similar chemical composition and each experimental sample. The total area of the five major peaks in each sample was then compared with that of the reference sample. The reference sample was obtained according to Example 11 of EP-A-565364. The diffraction patterns were measured on a Siemens D5000 diffractometer using CuKalpha radiation. The samples were finely ground and compacted in a backfilling sample holder. Data was collected in the region 9 to 37 degrees two Theta using a step side of 0.05 degrees and counting for 6 seconds at each step. The x-ray tube voltage was set at 40 kV and the current at 40 mA.
The recorded diffraction patterns were analyzed using the "Profile Fitting" routine within the Siemens Diffrac-AT v3.0 computer software package. Firstly the scattered x-ray intensity is removed with manual adjustment of the "Curvature" option. Care is taken to minimise the curvature so as not to remove real peak area. Then the peaks to be measured are identified, these have the approximate d-spacings: 7.1; 5.0; 4.1; 3.2 and 2.7 Angstroms. They are fitted to the most suitable mathematical function within the data handling program. In this case the Voigt function was found to best fit all five of the peaks of the reference sample. The same function was used to fit the peaks of the experimental samples. With each peak described mathematically the analysis package is able to calculate the area of each peak. If R is the total area of the peaks of the reference sample, and S the total area of the peaks of the experimental sample then the degree of crystallinity can be expressed as follows:
It is a first object of the present invention to
REFERENCES:
patent: 4289740 (1981-09-01), Estes
patent: 4314979 (1982-02-01), Deabriges
patent: 4649036 (1987-03-01), Pastorello et al.
patent: 5326466 (1994-11-01), Araya et al.
patent: 5374370 (1994-12-01), Brown et al.
Edwards Richard B.
Graham Peter
Bell Mark L.
Crosfield Limited
Sample David
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