Chemistry of inorganic compounds – Zeolite – Organic compound used to form zeolite
Reexamination Certificate
1999-04-21
2002-09-03
Sample, David (Department: 1755)
Chemistry of inorganic compounds
Zeolite
Organic compound used to form zeolite
C423S718000, C423SDIG002, C502S062000, C502S077000
Reexamination Certificate
active
06444191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing crystalline zeolite ZSM-11 using a templating agent comprising at least one 3,5-dimethylpiperidinium (3,5-DMP) compound, and to zeolite ZSM-11 in pure phase form.
2. State of the Art
Zeolite ZSM-11 and methods for making it are known. For example, U.S. Pat. No. 3,709,979, issued Jan. 9, 1973 to Chu, discloses the preparation of ZSM-11 using quaternary cations of a Group 5-A element, such as ammonium and phosphonium compounds, as the organic templating agent. It does not, however, disclose the 3,5-DMP compounds of this invention as templating agents. U.S. Pat. No. 3,709,979 is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,108,881, issued Aug. 22, 1978 to Rollman et al., teaches the synthesis of ZSM-11 using C
7
-C
12
alkylenediamines as the organic templating agent.
U.S. Pat. No. 4,894,212, issued Jan. 16, 1990 to McWilliams et al., discloses a method for synthesizing ZSM-11 using octylamine as the organic templating agent.
U.S. Pat. No. 4,941,963, issued Jul. 17, 1990 to Valyocsik, discloses a method for synthesizing ZSM-11 from a reaction mixture containing a diquaternary ammonium templating agent.
It is alleged that pure ZSM-11 has been synthesized using tetrabutylphosphonium, tetrabutylammonium and 1,8-diaminooctane (C
8
) and 1,9-diaminononane (C
9
). See P. A. Jacobs and J. A. Martens,
Studies in Surface Science and Catalysis,
33, p. 147-166.
Lok et al., in
Zeolites,
3, 282-291 (1983), disclose numerous compounds which act as templating agents for the synthesis of various crystalline materials, including ZSM-11. This article does not, however, disclose the organic templating agent of the present invention for the synthesis of ZSM-11.
U.S. Pat. No. 5,213,786, issued May 25, 1993 to Beck et al., discloses the synthesis of ZSM-11 using a trimethyl ammonium cation having the formula C
n
N
+
(CH
3
)
3
where n is 9, 10, 11, or 12 as the organic templating agent. These trimethylammonium compounds are said to supply the proper pore-filling and charge density balance to produce ZSM-11 at the expense of ZSM-5.
It has now been found that ZSM-11 can be prepared using 3,5-DMP compounds as the templating agent and that the resulting ZSM-11 product is in pure phase form.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a process for preparing the zeolite ZSM-11 which comprises:
(a) preparing an aqueous solution containing sources of (1) an alkali metal oxide, alkaline earth metal oxide or mixtures thereof; (2) an oxide selected from the oxides of aluminum, boron, iron, gallium, indium, titanium, or mixtures thereof; (3) an oxide selected from oxides of silicon, germanium or mixtures thereof; and (4) at least one 3,5-dimethylpiperidinium compound;
(b) maintaining the aqueous solution under conditions sufficient to form crystals of ZSM-11; and
(c) recovering the crystals of ZSM-11.
The present invention also provides this process further comprising replacing alkali and/or alkaline earth metal cations of the recovered ZSM-11, at least in part, by ion exchange with a cation or mixture of cations selected from the group consisting of hydrogen and hydrogen precursors, rare earth metals, and metals from Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB, and VIII of the Periodic Table of Elements.
The present invention also provides a crystalline material composition, as-synthesized and in the anhydrous state, whose general formula, in terms of mole ratios, is (from about 1 to about 50)Q: (from about 0.5 to about 25) M
2
O: (less than about 6.7)W
2
O
3
: 100 YO
2
wherein: Q is a 3,5-dimethylpiperidinium compound; M is alkali metal cations and/or alkaline earth metal cations; W is aluminum, boron, gallium, indium, iron, titanium, or mixtures thereof; and Y is silicon, germanium, or mixtures thereof.
In accordance with the present invention, there is also provided the zeolite ZSM-11 having no intergrowth within its crystalline structure of any other crystalline structure. In particular, the zeolite ZSM-11 of this invention has no intergrowth of ZSM-5 crystalline structure.
The present invention further provides the zeolite ZSM-11 having no intergrowth within its crystalline structure of any other crystalline structure and having the X-ray diffraction pattern of Table I or Table II below.
The present invention also provides the zeolite ZSM-11 having a SiO
2
/Al
2
O
3
mole ratio of less than 40.
Further provided in accordance with this invention is the zeolite ZSM-11 having a SiO
2
/Al
2
O
3
mole ratio of less than 40 and having a cyclohexane micropore volume of at least about 0.08 ml/g.
Among other factors, the present invention is based on the discovery that the zeolite ZSM-11 can be made using 3,5-dimethylpiperidinium compounds as the organic templating agent. It is especially surprising that, by using these 3,5-dimethylpiperidinium compounds as the templating agent, ZSM-11 can be prepared in essentially pure phase form. Heretofore, it has been difficult to prepare ZSM-11 using conventional templating agents without also crystallizing the closely related zeolite ZSM-5. Also, the present invention permits the synthesis of ZSM-11 with relatively low SiO
2
/Al
2
O
3
mole ratios, i.e., on the order of 25-40. In addition, it has surprisingly been found that the ZSM-11 prepared in accordance with this invention having a SiO
2
/Al
2
O
3
mole ratio of less than 40 has a high cyclohexane micropore volume, ie., at least about 0.08 ml/g.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In its process embodiment the present invention comprises:
(a) preparing an aqueous solution comprising sources of oxides capable of forming ZSM-11 and at least one 3,5-dimethylpiperidinium compound;
(b) maintaining the aqueous solution under conditions sufficient to form crystals of ZSM-11; and
(c) recovering the crystals of ZSM-11.
The Templating Agent
The templating agents useful in the present process are water-soluble 3,5-dimethylpiperidinium compounds which are capable of acting as a templating agent to form ZSM-11. They have a molecular structure of the general form:
wherein R
1
and R
2
independently represent an alkyl group, either branched or unbranched, substituted or unsubstituted, containing from 1 to about 7 carbon atoms, with the proviso that R
1
and R
2
are not both methyl. In addition, R
1
and R2 together may comprise a cyclic alkyl ring system, which, including the positively charged nitrogen atom, contains from 4 to 7 atoms, said ring system being unsubstituted or substituted with branched or unbranched alkyl groups having, e.g., one to three carbon atoms. X is an anion which is not detrimental to the formation of the ZSM-11, such as those described below. Preferred 3,5-DMP compounds are 3,5-dimethyl-N,N-diethylpiperidinium compounds; 3,5-dimethyl-N-methyl-N-ethylpiperidinium compounds; spiro 3,5-dimethylpiperidinium compounds such as 1-azonia-3,5,7-trimethyl-spiro[5.41]decane compounds.
The anion for the salt may be essentially any anion such as halide or hydroxide which is not detrimental to the formation of the molecular sieve. As used herein, “halide” refers to the halogen anions, particularly fluorine, chlorine, bromine, iodine, and combinations thereof. Thus, representative anions include hydroxide, acetate, sulfate, carboxylate, tetrafluoroborate, and halides such as fluoride, chloride, bromide, and iodide. Hydroxide and iodide are particularly preferred as anions.
The Preparation of ZSM-11
The process of the present invention comprises forming a reaction mixture containing sources of alkali and/or alkaline earth metal (M) cations; an oxide of aluminum, boron, iron, gallium, indium, titanium, or mixtures thereof (W); an oxide of silicon, germanium or mixtures thereof (Y); a 3,5-DMP templating agent (Q); and water, said reaction mixture having a composition in terms of mole ratios within the following ranges:
Reactants
General
Preferred
YO
2
/W
2
O
3
15 and greater
25 and greater
OH
−
/YO
2
0.1-0.6
0.15-
Chevron U.S.A. Inc.
Sample David
Sheridan Richard J.
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