Molecular sieve abstract
Molecular sieve compositions having three-dimensional microporous
framework structures of GaO.sub.2 AlO.sub.2 and PO.sub.2 tetrahedral
oxide units are disclosed. These molecular sieves have an empirical
chemical composition on an anhydrous basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 ; and "x", "y"
and "z" represent the mole fractions of gallium, aluminum
and phosphorus, respectively, present as tetrahedral oxides. Their
use as adsorbents, catalysts, etc. is also disclosed.
Molecular sieve claims
We claim:
1. Crystalline molecular sieves having three-dimensional microporous
framework structures of GaO.sub.2 AlO.sub.2 and PO.sub.2 tetrahedral
units having an empirical chemical composition on an anhydrous basis
expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 and has a value of zero to about
0.3; and "x", "y" and "z" represent
the mole fractions of gallium, aluminum and phosphorus, respectively,
present as tetrahedral oxides, said mole fractions being such that
they are within the hexagonal compositional area defined by points,
A, B, C, D, E and F of FIG. 1 said crystalline molecular sieves
having a characteristic X-ray powder diffraction pattern which contains
at least the d-spacings set forth in one of the following Tables
A to V:
2. Crystalline molecular sieves according to claim 1 wherein "z"
is not greater than 0.60.
3. Crystalline molecular sieves according to claim 1 or 2 wherein
"m" is not greater than about 0.15.
4. Crystalline molecular sieves according to claim 1 wherein the
mole fractions of gallium, aluminum and phosphorus present as tetrahedral
oxides are within the tetragonal compositional area defined by points
a, b, c and d of FIG. 2.
5. Crystalline molecular sieves according to claim 4 wherein the
mole fractions of gallium, aluminum and phosphorus present as tetrahedral
oxides are within the hexagonal compositional area defined by points
e, f, g, h, i and j of FIG. 2.
6. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table A given in claim 1.
7. The crystalline molecular sieves of claim 6 wherein the X-ray
powder diffraction pattern set forth in Table A contains at least
the d-spacings set forth in the following Table AA:
8. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table B given in claim 1.
9. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table C given in claim 1.
10. The crystalline molecular sieves of claim 9 wherein the X-ray
powder diffraction pattern set forth in Table C contains at least
the d-spacings set forth in one of the following Tables CA and CB:
11. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table D given in claim 1.
12. The crystalline molecular sieves of claim 11 wherein the X-ray
powder diffraction pattern set forth in Table D contains at least
the d-spacings set forth in the following Table DA:
13. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table E given in claim 1.
14. The crystalline molecular sieves of claim 13 wherein the X-ray
powder diffraction pattern set forth in Table E contains at least
the d-spacings set forth in the following Table EA:
15. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table F given in claim 1.
16. The crystalline molecular sieves of claim 15 wherein the X-ray
powder diffraction pattern set forth in Table F contains at least
the d-spacings set forth in the following Table FA:
17. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table G given in claim 1.
18. The crystalline molecular sieves of claim 17 wherein the X-ray
powder diffraction pattern set forth in Table G contains at least
the d-spacings set forth in the following Table GA:
19. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table H given in claim 1.
20. The crystalline molecular sieves of claim 19 wherein the X-ray
powder diffraction pattern set forth in Table H contains at least
the d-spacings set forth in one of the following Tables HA and HB:
21. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table I given in claim 1.
22. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table J given in claim 1.
23. The crystalline molecular sieves of claim 22 wherein the X-ray
powder diffraction pattern set forth in Table J contains at least
the d-spacings set forth in the following Table JA:
24. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table K given in claim 1.
25. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table L given in claim 1.
26. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table M given in claim 1.
27. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table N given in claim 1.
28. The crystalline molecular sieves of claim 27 wherein the X-ray
powder diffraction pattern set forth in Table N contains at least
the d-spacings set forth in the following Table NA:
29. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table O given in claim 1.
30. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table P given in claim 1.
31. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table Q given in claim 1.
32. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table R given in claim 1.
33. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table S given in claim 1.
34. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table T given in claim 1.
35. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table U given in claim 1.
36. The crystalline molecular sieves of claim 1 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table V given in claim 1.
37. Process for preparing crystalline molecular sieves having three-dimensional
microporous framework structures of GaO.sub.2 AlO.sub.2 and PO.sub.2
tetrahedral units having an empirical chemical composition on an
anhydrous basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 and has a value of zero to about
0.3; and "x", "y" and "z" represent
the mole fractions of gallium, aluminum and phosphorus, respectively,
present as tetrahedral oxides, said mole fractions being such that
they are within the hexagonal compositional area defined by points
A, B, C, D, E and F of FIG. 1 said crystalline molecular sieves
having a characteristic X-ray powder diffraction pattern which contains
at least the d-spacings set forth in one of the following Tables
A to V:
which process comprises providing a reaction mixture composition
at an effective temperature and for an effective time sufficient
to produce said molecular sieves, said reaction mixture composition
being expressed in terms of molar oxide ratios as follows:
wherein "R" is an organic templating agent; "a"
is an effective amount of "R" greater than zero; "b"
has a value of from zero to about 500; and "u", "v"
and "w" represent the mole fractions, respectively, of
gallium, aluminum and phosphorus in the (Ga.sub.u Al.sub.v P.sub.w)O.sub.2
constituent, and each has a value of at lest 0.01.
38. Process according to claim 37 wherein "u", "v"
and "w" are within the pentagonal compositional area defined
by points K, G, H, I and J of FIG. 3.
39. Process according to claim 37 wherein said reaction mixture
composition comprises from about 0.2 to about 0.5 moles of Ga.sub.2
O.sub.3 per mole of P.sub.2 O.sub.5.
40. Process according to claim 37 wherein said reaction mixture
composition comprises from about 0.3 to about 1.0 mole of Al.sub.2
O.sub.3 per mole of P.sub.2 O.sub.5.
41. Process according to claim 38 wherein "a" has a value
greater than zero to about 6.
42. Process according to claim 41 wherein "a" has a value
not greater than about 1.0.
43. Process according to claim 37 wherein "b" has a value
of not greater than about 20.
44. Process according to claim 37 wherein the source of phosphorus
in the reaction mixture is orthophosphoric acid.
45. Process according to claim 37 wherein the source of phosphorus
in the reaction mixture is orthophosphoric acid and the source of
aluminum is at least one compound selected from the group consisting
of pseudo-boehmite and aluminum alkoxide.
46. Process according to claim 45 wherein the aluminum alkoxide
is aluminum isopropoxide.
47. Process according to claim 37 wherein the source of gallium
is selected from the group consisting of oxides, hydroxides, alkoxides,
chlorides, bromides, iodides, sulfates, nitrates, carboxylates and
mixtures thereof.
48. Process according to claim 37 wherein the organic templating
agent is a quaternary ammonium or quaternary phosphonium compound
having the formula:
wherein X is nitrogen or phosphorus and each R is an alkyl or aryl
group containing from 1 to 8 carbon atoms.
49. Process according to claim 37 wherein the organic templating
agent is an amine.
50. Process according to claim 37 or claim 38 wherein the templating
agent is selected from the group consisting of tetrapropylammonium
ion; tetraethylammonium ion; tripropylamine; triethylamine; triethanolamine;
piperidine; cyclohexylamine; 2-methyl pyridine; N,N-dimethylbenzylamine;
N,N-dimethylethanolamine; choline; N,N-dimethylpiperazine; 14-diaziabicyclo-(222)
octane; N-methyldiethanolamine; N-methylethanolamine; N-methylpiperidine;
3-methylpiperidine; N-methylcyclohexylamine; 3-methylpyridine; 4-methylpyridine;
quinuclidine; N,N'-dimethyl-14 diazabicyclo (222) octane ion;
tetramethylammonium ion; tetrabutylammonium ion; tetrapentylammonium
ion; di-n-butylamine; neopentylamine; di-n-pentylamine; isopropylamine;
t-butylamine; ethylenediamine; pyrrolidine; 2-imidazolidone; di-n-propylamine;
and a polymeric quaternary ammonium salt [(C.sub.14 H.sub.32 N.sub.2)(OH).sub.2].sub.x
wherein x is a value of a least 2.
51. Molecular sieves prepared by calcining, at a temperature sufficiently
high to remove at least some of the organic templating agent present
in the intracrystalline pore system, the crystalline molecular sieves
having three-dimensional microporous framework structures of GaO.sub.2
AlO.sub.2 and PO.sub.2 tetrahedral units having an empirical chemical
composition on an anhydrous basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 and has a value of zero to about
0.3; and "x", "y" and "z" represent
the mole fractions of gallium, aluminum and phosphorus, respectively,
present as tetrahedral oxides, said mole fractions being such that
they are within the hexagonal compositional area defined by points
A, B, C, D, E and F of FIG. 1 said crystalline molecular sieves
having a characteristic X-ray powder diffraction pattern which contains
at least the d-spacings set forth in one of the following Tables
A to V:
Molecular sieve description
FIELD OF THE INVENTION
The instant invention relates to a novel class of crystalline microporous
molecular sieves, to the method of their preparation and to their
use as adsorbents and catalysts. The invention relates to novel
gallium-aluminum-phosphorus-oxide molecular sieves containing framework
tetrahedral oxide units of gallium, aluminum and phosphorus. These
compositions may be prepared hydrothermally from gels containing
reactive compounds of gallium, aluminum and phosphorus capable of
forming framework tetrahedral oxides, and preferably at least one
organic templating agent which functions in part to determine the
course of the crystallization mechanism and the structure of the
crystalline product.
BACKGROUND OF THE INVENTION
Molecular sieves of the crystalline aluminosilicate zeolite type
are well known in the art and now comprise over 150 species of both
naturally occurring and synthetic compositions. In general the crystalline
zeolites are formed from corner-sharing AlO.sub.2 and SiO.sub.2
tetrahedra and are characterized by having pore openings of uniform
dimensions, having a significant ion-exchange capacity and being
capable of reversibly desorbing an adsorbed phase which is dispersed
throughout the internal voids of the crystal without displacing
any atoms which make up the permanent crystal structure.
Other crystalline microporous compositions which are not zeolitic,
i.e. do not contain AlO.sub.2 tetrahedra as essential framework
constituents, but which exhibit the ion-exchange and/or adsorption
characteristics of the zeolites are also known. Metal organosilicates
which are said to possess ion-exchange properties, have uniform
pores and are capable of reversibly adsorbing molecules having molecular
diameters of about 6 .ANG. or less, are reported in U.S. Pat. No.
3941871 issued Mar. 2 1976 to Dwyer et al. A pure silica polymorph,
silicalite, having molecular sieving properties and a neutral framework
containing neither cations nor cation sites is disclosed in U.S.
Pat. No. 4061724 issued Dec. 6 1977 to R. W. Grose et al.
A recently reported class of microporous compositions and the first
framework oxide molecular sieves synthesized without silica, are
the crystalline aluminophosphate compositions disclosed in U.S.
Pat. No. 4310440 issued Jan. 12 1982 to Wilson et al. These materials
are formed from AlO.sub.2 and PO.sub.2 tetrahedra and have electrovalently
neutral frameworks as in the case of silica polymorphs. Unlike the
silica molecular sieve, silicalite, which is hydrophobic due to
the absence of extra-structural cations, the aluminophosphate molecular
sieves are moderately hydrophilic, apparently due to the difference
in electronegativity between aluminum and phosphorus. Their intracrystalline
pore volumes and pore diameters are comparable to those known for
zeolites and silica molecular sieves.
In U.S. Pat. No. 4440871 there is described a novel class of
silicon-substituted aluminophosphates which are both microporous
and crystalline. The materials have a three dimensional crystal
framework of PO.sub.2.sup.+, AlO.sub.2.sup.- and SiO.sub.2 tetrahedral
units and, exclusive of any alkali metal or calcium which may optionally
be present, an as-synthesized empirical chemical composition on
an anhydrous basis of:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the moles of "R" present per mole of (Si.sub.x
Al.sub.y P.sub.z)O.sub.2 and has a value of from zero to 0.3 the
maximum value in each case depending upon the molecular dimensions
of the templating agent and the available void volume of the pore
system of the particular silicoaluminophosphate species involved;
and "x", "y", and "z" represent the
mole fractions of silicon, aluminum and phosphorus, respectively,
present as tetrahedral oxides. The minimum value for each of "x",
"y", and "z" is 0.01 and preferably 0.02. The
maximum value for "x" is 0.98; for "y" is 0.60;
and for "z" is 0.52. These silicoaluminophosphates exhibit
several physical and chemical properties which are characteristic
of aluminosilicate zeolites and aluminophosphates.
In U.S. Pat. No. 4500651 there is described a novel class of
titanium-containing molecular sieves whose chemical composition
in the as-synthesized and anhydrous form is represented by the unit
empirical formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "M"
represents the moles of "R" present per mole of (Ti.sub.x
Al.sub.y P.sub.z)O.sub.2 and has a value of between zero and about
5.0; and "x", "y" and "z" represent
the mole fractions of titanium, aluminum and phosphorus, respectively,
present as tetrahedral oxides.
In U.S. Pat. No. 4567029 there is described a novel class of
crystalline metal aluminophosphates having three-dimensional microporous
framework structures of MO.sub.2 AlO.sub.2 and PO.sub.2 tetrahedral
units and having an empirical chemical composition on an anhydrous
basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the moles of "R" present per mole of (M.sub.x
Al.sub.y P.sub.z)O.sub.2 and has a value of from zero to 0.3; "M"
represents at least one metal of the group magnesium, manganese,
zinc and cobalt; "x", "y", and "z"
represent the mole fractions of the metal "M", aluminum
and phosphorus, respectively, present as tetrahedral oxides.
In U.S. Pat. No. 4544143 there is described a novel class of
crystalline ferroaluminophosphates having a three-dimensional microporous
framework structure of FeO.sub.2 AlO.sub.2 and PO.sub.2 tetrahedral
units and having an empirical chemical composition on an anhydrous
basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the moles of "R" present per mole of (Fe.sub.x
Al.sub.y P.sub.z)O.sub.2 and has a value of from zero to 0.3; and
"x", "y" and "z" represent the mole
fractions of the iron, aluminum and phosphorus, respectively, present
as tetrahedral oxides.
The instant invention relates to new molecular sieve compositions
having framework tetrahedral units of GaO.sub.2.sup.-, AlO.sub.2.sup.-
and PO.sub.2.sup.+.
DESCRIPTION OF THE FIGURES
FIG. 1 is a ternary diagram wherein parameters relating to the
instant compositions are set forth as mole fractions.
FIG. 2 is a ternary diagram wherein parameters relating to preferred
compositions are set forth as mole fractions.
FIG. 3 is a ternary diagram wherein parameters relating to the
reaction mixtures employed in the preparation of the compositions
of this invention are set forth as mole fractions.
SUMMARY OF THE INVENTION
The instant invention relates to a new class of gallium-aluminum-phosphorus-oxide
molecular sieves having a crystal framework structure of GaO.sub.2.sup.-,
AlO.sub.2.sup.- and PO.sub.2.sup.+ tetrahedral oxide units. These
new molecular sieves exhibit ion-exchange, adsorption and catalytic
properties and, accordingly, find wide use as adsorbents and catalysts.
The members of this novel class of compositions have crystal framework
structures of GaO.sub.2.sup.-, AlO.sub.2.sup.- and PO.sub.2.sup.+
tetrahedral units and have an empirical chemical composition on
an anhydrous basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 and has a value of zero to about
0.3; and "x", "y" and "z" represent
the mole fractions of gallium, aluminum and phosphorus, respectively,
present as tetrahedral oxides. These molecular sieve compositions
comprise crystalline molecular sieves having a three-dimensional
microporous framework structure of GaO.sub.2.sup.-, AlO.sub.2.sup.-
and PO.sub.2.sup.+ tetrahedral units.
The molecular sieves of the instant invention will be generally
referred to by the acronym "GaAPO" to designate the framework
of GaO.sub.2.sup.-, AlO.sub.2.sup.- and PO.sub.2.sup.+ tetrahedral
units. Actual class members will be identified by denominating the
various structural species which make up the GaAPO class by assigning
a number and, accordingly, are identified as "GaAPO-i"
wherein "i" is an integer. The given species designation
is not intended to denote a similarity in structure to any other
species denominated by a numbering system.
DETAILED DESCRIPTION OF THE INVENTION
The instant invention relates to a new class of gallium-aluminum-phosphorus-oxide
molecular sieves comprising a crystal framework structure of GaO.sub.2.sup.-,
AlO.sub.2.sup.- and PO.sub.2.sup.+ tetrahedral oxide units. These
new molecular sieves exhibit ion-exchange, adsorption and catalytic
properties and, accordingly, find wide use as adsorbents and catalysts.
The GaAPO molecular sieves have three-dimensional microporous framework
structures of GaO.sub.2.sup.-, AlO.sub.2.sup.-, and PO.sub.2.sup.+
tetrahedral oxide units having an empirical chemical composition
on an anhydrous basis expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the intracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ga.sub.x Al.sub.y P.sub.z)O.sub.2 and has a value of zero to about
0.3 but is preferably not greater than about 0.15; and "x",
"y" and "z" represent the mole fractions of
gallium, aluminum and phosphorus, respectively, present as tetrahedral
oxides. The mole fractions "x", "y", and "z"
are generally defined as being within the hexagonal compositional
area defined by points A, B, C, D, E and F of the ternary diagram
of FIG. 1. Points A, B, C, D, E and F of FIG. 1 have the following
values for "x", "y", and "z":
______________________________________ Mole Fraction Point x y
z ______________________________________ A 0.01 0.60 0.39 B 0.01
0.34 0.65 C 0.34 0.01 0.65 D 0.60 0.01 0.39 E 0.60 0.39 0.01 F 0.39
0.60 0.01 ______________________________________
In general, the value of "z" in the GaAPO molecular sieves
will be not greater than 0.60 so that the compositions will lie
within the hexagonal compositional area defined by points A, M,
N, D, E and F of the ternary diagram of FIG. 1 where points M and
N have the following values for "z", "y", and
"z":
______________________________________ Mole Fraction Point x y
z ______________________________________ M 0.01 0.39 0.60 N 0.39
0.01 0.60 ______________________________________
In a preferred subclass of the GaAPO molecular sieves the values
of "x", "y" and "z" in the above formula
are within the tetragonal compositional area defined by the points
a, b, c and d of the ternary diagram which is FIG. 2 of the drawings,
said points a, b, c and d representing the following values for
"x", "y" and "z":
______________________________________ Mole Fraction Point x y
z ______________________________________ a 0.01 0.59 0.40 b 0.01
0.34 0.65 c 0.34 0.01 0.65 d 0.59 0.01 0.40 ______________________________________
In an especially preferred subclass of the GaAPO molecular sieves
the values "x", "y" and "z" in the
formula are within the hexagonal compositional area defined by the
points, e, f, g, h, i and j of the ternary diagram which is FIG.
2 of the drawings, said points e, f, g, h, i and j representing
the following values for "x", "y" and "z":
______________________________________ Mole Fraction Point x y
z ______________________________________ e 0.03 0.52 0.45 f 0.03
0.33 0.64 g 0.16 0.20 0.64 h 0.25 0.20 0.55 i 0.25 0.33 0.42 j 0.06
0.52 0.42 ______________________________________
In GaAPOs of this invention are useful as adsorbents, catalysts,
ion-exchangers, and the like in much the same fashion as aluminosilicates
have been employed heretofore, although their chemical and physical
properties are not necessarily similar to those observed for aluminosilicates.
GaAPO compositions are generally synthesized by hydrothermal crystallization
from a reaction mixture containing reactive sources of gallium,
aluminum and phosphorus, preferably an organic templating, i.e.,
structure-directing, agent, preferably a compound of an element
of Group VA of the Periodic Table, and/or optionally an alkali or
other metal. The reaction mixture is generally placed in a sealed
pressure vessel, preferably lined with an inert plastic material
such as polytetrafluoroethylene and heated, preferably under autogenous
pressure, at a temperature between 50.degree. and 250.degree. C.,
and preferably between 100.degree. C. and 200.degree. C. until crystals
of the GaAPO product are obtained, usually a period of from several
hours to several weeks. Typical crystallization times are from about
2 hours to about 30 days, with from about 4 hours to about 20 days,
and preferably about 1 to about 7 days, being generally employed
to obtain crystals of the GaAPO products. The product is recovered
by any convenient method such as centrifugation or filtration.
In synthesizing the GaAPO compositions of the instant invention,
it is preferred to employ a reaction mixture composition expressed
in terms of the molar ratios as follows:
wherein "R" is an organic templating agent; "a"
is the amount of organic templating agent "R" and has
a value of from zero to about 6 and is preferably an effective amount
within the range of greater than zero (0) to about 6 and most preferably
not more than about 1.0; "b" has a value of from zero
(0) to about 500 preferably between about 2 and about 300 most
preferably between about 2 and about 20; and --u--, --v-- and --w--
represent the mole fractions of gallium, aluminum and phosphorus,
respectively, and each has a value of at least 0.01. The mole fractions
--u--, --v-- and --w-- in the reaction mixture are preferably within
the pentagonal compositional area defined by points G, H, I, J and
K which is shown in FIG. 3 of the drawings, where points G, H, I,
J and K have the following values for --u--, --v-- and --w--:
______________________________________ Mole Fraction Point u v
w ______________________________________ G 0.01 0.60 0.39 H 0.01
0.39 0.60 I 0.39 0.01 0.60 J 0.98 0.01 0.01 K 0.39 0.60 0.01 ______________________________________
In especially preferred reaction mixtures, from 0.2 to 0.5 mole
of Ga.sub.2 O.sub.3 and from 0.3 to 1 mole of Al.sub.2 O.sub.3 are
present for each mole of P.sub.2 O.sub.5.
In the foregoing expression of the reaction composition, the reactants
are normalized with respect to the total of u+v+w=1.00 mole, whereas
in the examples the reaction mixtures are expressed in terms of
the molar oxide ratios and may be normalized to 1.00 mole of P.sub.2
O.sub.5 or Al.sub.2 O.sub.3 This latter form is readily converted
to the former form by routine calculation by dividing the total
number of moles of gallium, aluminum and phosphorus into the moles
of each of gallium, aluminum and phosphorus. The moles of template
and water are similarly normalized by dividing by the total moles
of gallium, aluminum and phosphorus.
In forming the reaction mixture from which the instant molecular
sieves are formed the organic templating agent can be any of those
heretofore proposed for use in the synthesis of conventional zeolite
aluminosilicates. In general these compounds contain elements of
Group VA of the Periodic Table of Elements, particularly nitrogen,
phosphorus, arsenic and antimony, preferably nitrogen or phosphorus
and most preferably nitrogen, which compounds also contain at least
one alkyl or aryl group having from 1 to 8 carbon atoms. Particularly
preferred compounds for use as templating agents are the amines,
quaternary phosphonium and quaternary ammonium compounds, the latter
being represented generally by the formula R.sub.4 X.sup.+ wherein
"X" is nitrogen or phosphorus and each R is an alkyl or
aryl group containing from 1 to 8 carbon atoms. Polymeric quaternary
ammonium salts such as [(C.sub.14 H.sub.32 N.sub.2)(OH).sub.2 ].sub.x
wherein "x" has a value of at least 2 are also suitably
employed. The mono-, di- and tri-amines are advantageously utilized,
either alone or in combination with a quaternary ammonium compound
or other templating compound. Mixtures of two or more templating
agents can either produce mixtures of the desired GaAPOs or the
more strongly directing templating species may control the course
of the reaction with the other templating species serving primarily
to establish the pH conditions of the reaction gel. Representative
templating agents include tetramethylammonium, tetraethylammonium,
tetrapropylammonium or tetrabutylammonium ions; tetrapentylammonium
ion; di-n-propylamine; tripropylamine; triethylamine; triethanolamine;
piperidine; cyclohexylamine; 2-methylpyridine; N,N-dimethylbenzylamine;
N,N-dimethylethanolamine; choline; N,N'-dimethylpiperazine; 14-diazabicyclo
(222) octane; N-methyldiethanolamine, N-methylethanolamine; N-methylpiperidine;
3-methylpiperidine; N-methylcyclohexylamine; 3-methylpyridine; 4-methylpyridine;
quinuclidine; N,N'-dimethyl-14-diazabicyclo (222) octane ion;
di-n-butylamine, neopentylamine; di-n-pentylamine; isopropylamine;
t-butylamine; ethylenediamine; pyrrolidine; and 2-imidazolidone.
Not every templating agent will direct the formation of every species
of GaAPO, i.e., a single templating agent can, with proper manipulation
of the reaction condition, direct the formation of several GaAPO
compositions, and a given GaAPO composition can be produced using
several different templating agents.
The reactive phosphorus source is preferably phosphoric acid, but
organic phosphates such as triethyl phosphate may be satisfactory,
and so also may crystalline or amorphous aluminophosphates such
as the AlPO.sub.4 composition of U.S. Pat. No. 4310440. Organo-phosphorus
compounds, such as tetrabutylphosphonium bromide, do not apparently
serve as reactive sources of phosphorus, but these compounds may
function as templating agents. Conventional phosphorus salts such
as sodium metaphosphate, may be used, at least in part, as the phosphorus
source, but are not preferred.
The preferred aluminum source is either an aluminum alkoxide, such
as aluminum isoproproxide, or pseudoboehmite. The crystalline or
amorphous aluminophosphates which are a suitable source of phosphorus
are, of course, also suitable sources of aluminum. Other sources
of aluminum used in zeolite synthesis, such as gibbsite, sodium
aluminate and aluminum trichloride, can be employed but are not
preferred.
The reactive source of gallium can be introduced into the reaction
system in any form which permits the formation in situ of a reactive
form of gallium, i.e., reactive to form the framework tetrahedral
oxide unit of gallium. Compounds of gallium which may be employed
include oxides, alkoxides, hydroxides, chlorides, bromides, iodides,
nitrates, sulfates, carboxylates (e.g., acetates) and the like.
While not essential to the synthesis of GaAPO compositions, stirring
or other moderate agitation of the reaction mixture and/or seeding
the reaction mixture with seed crystals of either the GaAPO species
to be produced or a topologically similar aluminophosphate, aluminosilicate
or molecular sieve composition, facilitates the crystallization
procedure.
After crystallization the GaAPO product may be isolated and advantageously
washed with water and dried in air. The as-synthesized GaAPO generally
contains within its internal pore system at least one form of the
templating agent employed in its formation. Most commonly the organic
moiety is present, at least in part, as a charge-balancing cation
as is generally the case with as-synthesized aluminosilicate zeolites
prepared from organic-containing reaction systems. It is possible,
however, that some or all of the organic moiety is an occluded molecular
species in a particular GaAPO species. As a general rule the templating
agent, and hence the occluded organic species, is too large to move
freely through the pore system of the GaAPO product and must be
removed by calcining the GaAPO at temperatures of 200.degree. C.
to 700.degree. C., preferably about 350.degree. C. to about 600.degree.
C., to thermally degrade the organic species. In a few instances
the pores of the GaAPO product are sufficiently large to permit
transport of the templating agent, particularly if the latter is
a small molecule, and accordingly complete or partial removal thereof
can be accomplished by conventional desorption procedures such as
carried out in the case of zeolites. It will be understood that
the term "as synthesized" as used herein does not include
the condition of the GaAPO phase wherein the organic moiety occupying
the intracrystalline pore system as a result of the hydrothermal
crystalline process has been reduced by post-synthesis treatment
such that the value of "m" in the composition formula
has a value of less than 0.02. The other symbols of the formula
are as defined hereinabove. In those preparations in which an alkoxide
is employed as the source of gallium, aluminum or phosphorus, the
corresponding alcohol is necessarily present in the reaction mixture
since it is a hydrolysis product of the alkoxide. It has not been
determined whether this alcohol participates in the synthesis process
as a templating agent. For the purposes of this application, however,
this alcohol is arbitrarily omitted from the class of templating
agents, even if it is present in the as-synthesized GaAPO material.
Since the present GaAPO compositions are formed from GaO.sub.2
AlO.sub.2 PO.sub.2 tetrahedral units which, respectively, have
a net charge of -1 -1 and +1 the matter of cation exchangeability
is considerably more complicated than in the case of zeolitic molecular
sieves in which, ideally, there is a stoichiometric relationship
between AlO.sub.2.sup.- tetrahedra and charge-balancing cations.
In the instant compositions, an AlO.sub.2.sup.- tetrahedron can
be balanced electrically either by association with a PO.sub.2.sup.+
tetrahedron or a simple cation such as an alkali metal cation, a
proton (H.sup.+), a cation of gallium present in the reaction mixture,
or an organic cation derived from the templating agent. Similarly,
a GaO.sub.2.sup.- tetrahedron can be balanced electrically by association
with PO.sub.2.sup.+ tetrahedra, a cation of gallium present in the
reaction mixture, a simple cation such as an alkali metal cation,
a proton (H.sup.+), organic cations derived from the templating
agent, or other divalent or polyvalent metal cations introduced
from an extraneous source. It has also been postulated that non-adjacent
AlO.sub.2.sup.- and PO.sub.2.sup.+ tetrahedral pairs can be balanced
by Na.sup.+ and OH.sup.- respectively [Flanigen and Grose, Molecular
Sieve Zeolites-I, ACS, Washington, D.C. (1971)].
The GaAPO compositions of the present invention may exhibit cation-exchange
capacity when analyzed using ion-exchange techniques heretofore
employed with zeolitic aluminosilicates and have pore diameters
which are inherent in the lattice structure of each species and
which are at least about 3 .ANG. in diameter. Ion exchange of GaAPO
compositions would ordinarily be possible only after any organic
moiety derived from the template, present as a result of synthesis,
has been removed from the pore system. Dehydration to remove water
present in the as-synthesized GaAPO compositions can usually be
accomplished, to some degree at least, in the usual manner without
removal of the organic moiety, but the absence of the organic species
greatly facilitates adsorption and desorption procedures. The GaAPO
materials have various degrees of hydrothermal and thermal stability,
some being quite remarkable in this regard, and function well as
molecular sieve adsorbents and hydrocarbon conversion catalysts
or catalyst bases.
In preparing the GaAPO composition it is preferred to use a stainless
steel reaction vessel lined with an inert plastic material, e.g.,
polytetrafluoroethylene, to avoid contamination of the reaction
mixture. In general, the final reaction mixture from which each
GaAPO composition is crystallized is prepared by forming mixtures
of less than all of the reagents and thereafter incorporating into
these mixtures additional reagents either singly or in the form
of other intermediate mixtures of two or more reagents. In some
instances the reagents admixed retain their identity in the intermediate
mixture and in other cases some or all of the reagents are involved
in chemical reactions to produce new reagents. The term "mixture"
is applied in both cases. Further, it is preferred that the intermediate
mixtures as well as the final reaction mixtures be stirred until
substantially homogeneous.
X-ray patterns of reaction products are obtained by X-ray analysis
using standard X-ray powder diffraction techniques. The radiation
source is a high-intensity, copper target, X-ray tube operated at
50 Kv and 40 ma. The diffraction pattern from the copper K-alpha
radiation and graphite monochromator is suitably recorded by an
X-ray spectrometer scintillation counter, pulse height analyzer
and strip chart recorder. X-ray patterns are obtained using flat
compressed powder samples which are scanned at 2.degree. (2 theta)
per minute, using a two second time constant. Interplanar spacings
(d) in Angstrom units are obtained from the position of the diffraction
peaks expressed as 2.theta. where .theta. is the Bragg angle as
observed on the strip chart. Intensities are determined from the
heights of diffraction peaks after subtracting background, "I.sub.o
"being the intensity of the strongest line or peak, and "I"
being the intensity of each of the other peaks. Alternatively, the
X-ray patterns may be obtained by use of computer based techniques
using copper K alpha radiation, Siemens type K-805 X-ray sources
and Siemens D-500 X-ray powder diffractometers, available from Siemens
Corporation, Cherry Hill, N.J.
As will be understood by those skilled in the art the determination
of the parameter 2 theta is subject to both human and mechanical
error, which in combination, can impose an uncertainty of about
.+-.0.4.degree. on each reported value of 2 theta. This uncertainty
is, of course, also manifested in the reported values of the d-spacings,
which are calculated from the 2 theta values. This imprecision is
general throughout the art and is not sufficient to preclude the
differentiation of the present crystalline materials from each other
and from the compositions of the prior art. In some of the X-ray
patterns reported, the relative intensities of the d-spacings are
indicated by the notations vs, s, m, w and vw which represent very
strong, strong, medium, weak and very weak, respectively.
In certain instances the purity of a synthesized product may be
assessed with reference to its X-ray powder diffraction pattern.
Thus, for example, if a sample is stated to be pure, it is intended
only that the X-ray pattern of the sample is free of lines attributable
to crystalline impurities, not that there are no amorphous materials
present.
The molecular sieves of the instant invention may be characterized
by their X-ray powder diffraction patterns and as such may have
one of the X-ray patterns set forth in the following Tables A through
V, wherein said X-ray patterns are for the as-synthesized form unless
otherwise noted. In most cases, the pattern of the corresponding
calcined form will also fall within the relevant Table. However,
in some cases the removal of the occluded templating agent which
occurs during calcination will be accompanied by sufficient relaxation
of the lattice to shift some of the lines slightly outside the ranges
specified in the relevant Table. In a small number of cases (e.g.
GaAPO-33), calcination appears likely to cause more substantial
distortions in the crystal lattice, and hence more significant changes
in the X-ray power diffraction pattern.
PROCESS APPLICATIONS
The GaAPO compositions of the present invention are, in general,
hydrophilic and adsorb water preferentially over common hydrocarbon
molecules such as paraffins, olefins and aromatic species, e.g.,
benzene, xylenes and cumene. Thus the present molecular sieve compositions
as a class are useful as desiccants in such adsorption separation/purification
processes as natural gas drying, cracked gas drying. Water is also
preferentially adsorbed over the so-called permanent gases such
as carbon dioxide, nitrogen, oxygen and hydrogen. These GaAPOs are
therefore suitably employed in the drying of reformer hydrogen streams
and in the drying of oxygen, nitrogen or air prior to liquifaction.
The present GaAPO compositions also exhibit novel surface selectivity
characteristics which render them useful as catalyst or catalyst
bases in a number of hydrocarbon conversion and oxidative combustion
reactions. They can be impregnated or otherwise loaded with catalytically
active metals by methods well known in the art (e.g. ion exchange
or impregnation) and used, for example, in fabricating catalyst
compositions having silica or alumina bases. Of the general class,
those species having pores larger than about 4 .ANG. are preferred
for catalytic applications.
Among the hydrocarbon conversion reactions catalyzed by GaAPO compositions
are cracking, hydrocracking, alkylation for both the aromatic and
isoparaffin types, isomerization including xylene isomerization,
polymerization, reforming, hydrogenation, dehydrogenation, transalkylation,
dealkylation, hydrodecyclization and dehydrocyclization.
Using GaAPO catalyst compositions which contain a hydrogenation
promoter such as platinum or palladium, heavy petroleum residual
stocks, cyclic stocks and other hydrocrackable charge stocks, can
be hydrocracked at temperatures in the range of 400.degree. F. to
825.degree. F. (204.degree. C. to 441.degree. C.) using molar ratios
of hydrogen to hydrocarbon in the range of between 2 and 80 pressures
between 10 and 3500 p.s.i.g. (0.171 to 24.23 MPa.), and a liquid
hourly space velocity (LHSV) of from 0.1 to 20 preferably 1.0 to
10.
The GaAPO catalyst compositions employed in hydrocracking are also
suitable for use in reforming processes in which the hydrocarbon
feedstocks contact the catalyst at temperatures of from about 700.degree.
F. to 1000.degree. F. (371.degree. C. to 538.degree. C.), hydrogen
pressures of from 100 to 500 p.s.i.g. (0.791 to 3.448 MPa.), LHSV
values in the range of 0.1 to 10 and hydrogen to hydrocarbon molar
ratios in the range of 1 to 20 preferably between 4 and 12.
These same catalysts, i.e. those containing hydrogenation promoters,
are also useful in hydroisomerization processes in which feedstocks
such as normal paraffins are converted to saturated branched chain
isomers. Hydroisomerization is carried out at a temperature of from
about 200.degree. F. to 600.degree. F. (93.degree. C. to 316.degree.
C.), preferably 300.degree. F. to 550.degree. F. (149.degree. C.
to 288.degree. C.) with an LHSV value of from about 0.2 to 1.0.
Hydrogen (H) is supplied to the reactor in admixture with the hydrocarbon
(Hc) feedstock in molar proportions (H/Hc) of between 1 and 5.
At somewhat higher temperatures, i.e. from about 650.degree. F.
to 1000.degree. F. (343.degree. C. to 538.degree. C.), preferably
850.degree. F. to 950.degree. F. (454.degree. C. to 510.degree.
C.) and usually at somewhat lower pressures within the range of
about 15 to 50 p.s.i.g. (205 to 446 KPa.), the same catalyst compositions
are used to hydroisomerize normal paraffins. Preferably the paraffin
feedstock comprises normal paraffins having a carbon number range
of C.sub.7 -C.sub.20. Contact time between the feedstock and the
catalyst is generally relatively short to avoid undesirable side
reactions such as olefin polymerization and paraffin cracking. LHSV
values in the range of 0.1 to 10 preferably 1.0 to 6.0 are suitable.
The unique crystal structure of the present GaAPO catalysts and
their availability in a form totally void of alkali metal content
favor their use in the conversion of alkylaromatic compounds, particularly
the catalytic disproportionation of toluene, ethylene, trimethyl
benzenes, tetramethyl benzenes and the like. In the disproportionation
process, isomerization and transalkylation can also occur. Group
VIII noble metal adjuvants alone or in conjunction with Group VI-B
metals such as tungsten, molybdenum and chromium are preferably
included in the catalyst composition in amounts of from about 3
to 15 weight-% of the overall composition. Extraneous hydrogen can,
but need not, be present in the reaction zone which is maintained
at a temperature of from about 400 to 750.degree. F. (204 to 399.degree.
C.), pressures in the range of 100 to 2000 p.s.i.g. (0.791 to 13.89
MPa.) and LHSV values in the range of 0.1 to 15.
Catalytic cracking processes are preferably carried out with GaAPO
compositions using feedstocks such as gas oils, heavy naphthas,
deasphalted crude oil residua, etc., with gasoline being the principal
desired product. Temperature conditions of 850.degree. to 1100.degree.
F. (454.degree. to 593.degree. C.), LHSV values of 0.5 to 10 and
pressure conditions of from about 0 to 50 p.s.i.g. (101 to 446 KPa.)
are suitable.
Dehydrocyclization reactions employing paraffinic hydrocarbon feedstocks,
preferably normal paraffins having more than 6 carbon atoms, to
form benzene, xylenes, toluene and the like are carried out using
essentially the same reaction conditions as for catalytic cracking.
For these reactions it is preferred to use the GaAPO catalyst in
conjunction with a Group VIII non-noble metal cation such as cobalt
and nickel.
In catalytic dealkylation wherein it is desired to cleave paraffinic
side chains from aromatic nuclei without substantially hydrogenating
the ring structure, relatively high temperatures in the range of
about 800.degree.-1000.degree. F. (427.degree.-538.degree. C.) are
employed at moderate hydrogen pressures of about 300-1000 p.s.i.g.
(2.17-6.895 MPa.), other conditions being similar to those described
above for catalytic hydrocracking. Preferred catalysts are of the
same type described above in connection with catalytic dehydrocyclization.
Particularly desirable dealkylation reactions contemplated herein
include the conversion of methylnaphthalene to naphthalene and toluene
and/or xylenes to benzene.
In catalytic hydrofining, the primary objective is to promote the
selective hydrodecomposition of organic sulfur and/or nitrogen compounds
in the feed, without substantially affecting hydrocarbon molecules
therein. For this purpose it is preferred to employ the same general
conditions described above for catalytic hydrocracking, and catalysts
of the same general nature described in connection with dehydrocyclization
operations. Feedstocks include gasoline fractions, kerosenes, jet
fuel fractions, diesel fractions, light and heavy gas oils, deasphalted
crude oil residua and the like. Any of these may contain up to about
5 weight-percent of sulfur and up to about 3 weight-percent of nitrogen.
Similar conditions can be employed to effect hydrofining, i.e.,
denitrogenation and desulfurization, of hydrocarbon feeds containing
substantial proportions of organonitrogen and organosulfur compounds.
It is generally recognized that the presence of substantial amounts
of such constituents markedly inhibits the activity of hydrocracking
catalysts. Consequently, it is necessary to operate at more extreme
conditions when it is desired to obtain the same degree of hydrocracking
conversion per pass on a relatively nitrogenous feed than with a
feed containing less organonitrogen compounds. Consequently, the
conditions under which denitrogenation, desulfurization and/or hydrocracking
can be most expeditiously accomplished in any given situation are
necessarily determined in view of the characteristics of the feedstocks,
in particular the concentration of organonitrogen compounds in the
feedstock. As a result of the effect of organonitrogen compounds
on the hydrocracking activity of these compositions it is not at
all unlikely that the conditions most suitable for denitrogenation
of a given feedstock having a relatively high organonitrogen content
with minimal hydrocracking, e.g., less than 20 volume percent of
fresh feed per pass, might be the same as those preferred for hydrocracking
another feedstock having a lower concentration of hydrocracking
inhibiting constituents e.g., organonitrogen compounds. Consequently,
it has become the practice in this art to establish the conditions
under which a certain feed is to be contacted on the basis of preliminary
screening tests with the specific catalyst and feedstock.
Isomerization reactions are carried out under conditions similar
to those described above for reforming, using somewhat more acidic
catalysts. Olefins are preferably isomerized at temperatures of
500.degree.-900.degree. F. (260.degree.-482.degree. C.), while paraffins,
naphthenes and alkyl aromatics are isomerized at temperatures of
700.degree.-1000.degree. F. (371.degree.-538.degree. C.). Particularly
desirable isomerization contemplated herein include the conversion
of n-heptene and/or n-octane to isoheptanes, iso-octanes, butane
to iso-butane, methylcyclopentane to cyclohexane, meta-xylene and/or
ortho-xylene to paraxylene, 1-butene to 2-butene and/or isobutene,
n-hexane to isohexene, cyclohexene to methylcyclopentene etc. The
preferred form of the catalyst is a combination of the GaAPO with
polyvalent metal compounds (such as sulfides) of metals of Group
II-A, Group II-B and rare earth metals. For alkylation and dealkylation
processes the GaAPO compositions having pores of at least 5 .ANG.
are preferred. When employed for dealkylation of alkyl aromatics,
the temperature is usually at least 350.degree. F. (177.degree.
C.) and ranges up to a temperature at which substantial cracking
of the feedstock or conversion products occurs, generally up to
about 700.degree. F. (371.degree. C.). The temperature is preferably
at least 450.degree. F. (232.degree. C.) and not greater than the
critical temperature of the compound undergoing dealkylation. Pressure
conditions are applied to retain at least the aromatic feed in the
liquid state. For alkylation the temperature can be as low as 250.degree.
F. (121.degree. C.) but is preferably at least 350.degree. F. (177.degree.
C.). In the alkylation of benzene, toluene and xylene, the preferred
alkylating agents are olefins such as ethylene and propylene.
The following example is provided to further illustrate the use
of the GaAPOs of the invention in one of the processes discussed
above, but is not intended to be limitative of the possible uses
of the GaAPOs.
EXAMPLE 20 (CRACKING TESTS ON GAAPO-26)
GaAPO-b 26 was prepared from a second aliquot of the reaction mixture
prepared in Example 17 above by digesting at 150.degree. C. for
122 hours, then isolating the product in the same way as in Example
17. The n-butane cracking activity of the GaAPO-26 product was tested
in a bench-scale apparatus, in which the reactor was a cylindrical
quartz tube 254 mm. in length and 10.3 mm. in internal diameter.
The reactor was loaded with 0.8 gram of the GaAPO-26. The reactor
was heated at 500.degree. C. under helium for 2 hours to calcine
the sample, then a feedstock comprising a helium/n-butane mixture
containing 2 mole percent of n-butane was passed through the reactor
at a rate of 50 mL/min. (STP) at 500.degree. C. for 10 minutes.
At the end of this period, the reactor effluent was analyzed using
conventional gas chromatography techniques. The resultant data showed
a pseudo-first-order rate constant (k.sub.A) of 0.6. |