Chemistry of inorganic compounds – Rare earth compound
Reexamination Certificate
2001-10-25
2004-09-28
Langel, Wayne A. (Department: 1754)
Chemistry of inorganic compounds
Rare earth compound
C423S305000, C423S306000
Reexamination Certificate
active
06797248
ABSTRACT:
This application claims priority of China 00123144.8, China 01106007.7 and China 01106006.9, filed Oct. 26, 2000, Jan. 5, 2001 and Jan. 5, 2001, respectively, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates to a molecular sieve, especially a mesoporous molecular sieve, and a process for the preparation of the same.
DESCRIPTION OF THE RELATED ART
Porous inorganic materials have been widely applied in the catalysis and adsorption separation fields mainly because these materials possess an abundant microporous structure and a larger specific surface area and can provide a great number of acid sites and active adsorption sites. These materials may be roughly classified into amorphous and crystalline and modified pillared-layer materials.
Amorphous materials are important catalyst supports which have been used in industry for many years. The most typical one is amorphous silica-alumina, which is an acidic catalyst and an important support of the reforming catalyst in petrochemical industry. Here “amorphous” means that the long range is disordered but the short range is generally ordered. The most commonly used methods for characterizing these materials are X-ray diffraction, pore structure analysis and transmission electronic microscopy. The appearance of porous crystalline materials has enlarged the categories of the porous materials, and greatly enriched theory of the porous materials and brought the petrochemical industry a revolution. Especially since the application of the porous crystalline materials in industry results in astonishing economic benefits, people have been carrying out deeper and more perfect investigations on the porous crystalline materials. Porous crystalline materials possess a unique, regular crystalline structure, and each has a pore structure with a definite shape and size. Micropores connect the pores to form “giant molecules” with abundant pores. Since such a pore structure only permits the molecule with a definite size to pass, this material is referred to as “molecular sieve” and this property of molecular sieves has been widely applied. The structure of these molecular sieves, no matter whether they are synthetic or natural, generally has three-dimensional framework structure., Those kinds of molecular sieves only contain Si, Al and O elements are customarily denoted as “zeolite”. Presently, many kinds of zeolites have been synthesized and widely applied, such as zeolite-A (U.S. Pat. No. 2,882,243), zeolite-X (U.S. Pat. No. 2,882,244), zeolite-Y (U.S. Pat. No. 3,130,007), ZSM-5 (U.S. Pat. No. 3,702,886), ZSM-11 (U.S. Pat. No. 3,709,979), etc. If Al or/and Si in the zeolites are partly or entirely substituted by other atoms, new types of molecular sieves will be formed. Now a variety of new types of molecular sieves have been synthesized and widely applied, such as SAPO series molecular sieves (U.S. Pat. Nos. 6,162,415, 5,370,851, 5,279,810, 5,230,881, 4,440,871, etc.), especially the SAPO-11 molecular sieves (U.S. Pat. Nos. 6,204,426, 6,111,160, 5,833,837, 5,246,566, 4,921,594, 4,499,315). Because these molecular sieves have a unique activity for the isomerization of long-chain alkanes, they are ideal components for the hydroisomerization of the wax in the lubricant oil fraction, and are widely used in the production of the basic oil of the top-grade lubricant oil.
Although the study on molecular sieves is quite mature, the pore diameters of most prepared molecular sieves are below 1.0 nm, and the maximum pore diameter reported in a literature is only 1.3 nm (Davis M E, Saldarriaga C, et al. Nature, 1991, 352: 320). Such molecular sieve still belongs to the micropore one which restricts the reaction of larger molecules. According to the definition of IUPAC, the material with pore diameter below 2 nm belongs to the microporous materials, and the material with pore diameter in the range of 2 nm to 50 nm belongs to the mesoporous material. Based on this definition, most of the prior molecular sieves belong to the microporous molecular sieves. Due to the development of the modern industry, the stricter and stricter environment protection law, and the worldwide tendency for the crude oil to become worse and heavier, it is an urgent task to develop a series of novel materials with super larger pore diameter and specific surface area, stable properties and excellent adsorptive and catalytic performances.
U.S. Pat. Nos. 5,108,725, 5,102,643, 5,098,684, and 5,057,296 disclose a process for synthesizing a mesoporous MCM-41 molecular sieve and its properties. This sort of molecular sieve has a structure of symmetric hexagonal. Its higher surface area, uniform pore distribution, adjustable pore diameter and acidity, accessible active sites, small diffusion resistance, ability to provide favorable space and effective acidic active sites for the large molecules, especially the heavy oil organic molecules to conduct the shape-selective reaction in the processes of petrochemical industry greatly encourage the chemical engineers. However, since the synthesis of such a molecular sieve requires large amounts of organic templates and auxiliary organic compounds such as cetyl trimethylammonium bromide (CTMAB), quaternary ammonium alkali and other organic compounds, and the resulting molecular sieve has so poor thermal stability (especially hydrothermal stability) that its crystal lattice can be retained in boiling water for only several hours or even shorter, it would be hard for them to have any value for practical applications.
Through the effort of recent years, some new mesoporous materials have been synthesized, but most of these materials are the improvements of MCM-41 which are, for example, synthesized by using new processes (U.S. Pat. Nos. 6,190,639, 6,096,287, 5,958,368, and 5,595,715, and Chinese Patent (Application) ZL 99103705.7, 96193321.6, and 95192999.2). Some hetero-atom substituted MCM-41 are synthesized (U.S. Pat. Nos. 6,193,943, 6,054,052, 6,042,807, 5,855,864, and 5,783,167, and Chinese Patent (Application) ZL.95105905.X, and 99107789.X) and thick wall MCM-41 is also synthesized (U.S. Pat. No. 6,193,943). However, the problem of the poor hydrothermal stability has not been substantively solved in these arts.
SUMMARY OF THE INVENTION
To overcome the shortages and problems of the above techniques, an object of the present invention is to provide a molecular sieve (hereinafter names it MPL-1), which has a character of mesoporous structure, larger and distribution concentrated pore diameters, larger specific surface and adsorption capacity, high thermal and hydrothermal stabilities. Meanwhile, a further object of the present invention is to provide a process for preparing such a molecular sieve.
The mesoporous molecular sieve provided by the present invention comprises at least three elements, i.e. phosphorus, aluminum, and oxygen, wherein the P
2
O
5
/Al
2
O
3
molar ratio is 0.5-1.5, preferably 0.7-1.3, and most preferably 0.7-1.0, and has a specific X-ray diffraction pattern.
The molecular sieve according to the present invention has a X-ray diffraction pattern on which its strongest diffraction peak is at the position 2&thgr;=1.5°-13.0° with the units d-spacing greater than 4.0 nm, preferably 4.0 nm-6.0 nm. Particularly, the molecular sieve according to the present invention has substantively the same X-ray diffraction pattern as shown in FIG.
1
.
The molecular sieve of the present invention has a pore diameter of 1.3 nm-10.0 nm, preferably 2.0 nm-10.0 nm, and most preferably 2.0 nm-5.0 nm.
The molecular sieve of the present invention may further contain elements Si and/or Ti, wherein the T/Al
2
O
3
molar ratio is 0.01-2.0, preferably 0.01-1.0, wherein T represents Si and/or Ti.
Besides aluminum and/or titanium, the molecular sieve of the present invention may further contain one or more other metal elements. The molar ratio of said other metal(s) to alumina M/Al
2
O
3
=0.01-2.0, preferably 0.01-1.0, and most preferably 0.1-0.5, wherein M rep
Liu Quanjie
Peng Yan
Yang Jun
China Petroleum and Chemical Corporation
Langel Wayne A.
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