Molecular sieve abstract
Molecular sieve compositions having three-dimensional microporous
framework structures of GeO.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
(Ge.sub.x Al.sub.y P.sub.z)O.sub.2 ; and "x", "y"
and "z" represent the mole fractions of germanium, aluminum
and phosphorus, respectively, present as tetrahedral oxides. Their
use as adsorbents, catalysts, etc. is also disclosed.
Molecular sieve claims
We claim:
1. A crystalline molecular sieve having a three-dimensional microporous
framework structure of GeO.sub.2 AlO.sub.2 and PO.sub.2 tetrahedral
units having an empirical chemical composition of an anhydrous basis
expressed by the formula:
wherein "R" represents at least one organic templating
agent present in the in-tracrystalline pore system; "m"
represents the molar amount of "R" present per mole of
(Ge.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 germanium, aluminum and phosphorous, respectively,
present as tetrahedral oxides, said fractions being such that they
are within the pentagonal compositional area defined by points A,
B, C, D and E 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
C, F, J, N, P, U and V;
2. The crystalline molecular sieve of claim 1 where the mole fractions
of germanium, aluminum and phosphorus present as tetrahedral oxides
are within the pentagonal compositional area defined by points a,
b, c, d and e of FIG. 2.
3. The crystalline molecular sieves of claim 1 or 2 having a characteristic
x-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table C given in claim 1.
4. The crystalline molecular sieves of claim 1 or 2 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table F given in claim 1.
5. The crystalline molecular sieves of claim 4 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;
6. The crystalline molecular sieves of claim 1 or 2 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table J given in claim 1.
7. The crystalline molecular sieves of claim 6 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;
8. The crystalline molecular sieves of claim 1 or 2 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table N given in claim 1.
9. The crystalline molecular sieves of claim 1 or 2 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table P given in claim 1.
10. The crytstalline molecular sieves of claim 1 or 2 having a
characterisic X-ray powder diffraction pattern which contains at
least the d-spacings set forth in Table U given in claim 1.
11. The crystalline molecular sieves of claim 1 or 2 having a characteristic
X-ray powder diffraction pattern which contains at least the d-spacings
set forth in Table V given in claim 1.
12. Molecular sieve prepared by calcining at a temperature sufficienty
hig to remove at least some of any organic templating agent present
in the intracrystalline pore system, a crystalline molecular sieve
having three-dimensional microporous framework structures of GeO.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
(Ge.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 germanium, aluminum and phosphorus, respectively,
present as tetrahedral oxides, said mole fractions being such that
they are within the pentagonal compostional area defined by points
A, B, C, D and E 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
C, F, J, N, U and V;
13. Process for preparing crystalline molecular sieves having three-dimensional
framework structures of GeO.sub.2 AlO.sub.2 and PO.sub.3 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
(Ge.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 germanium, aluminum and phosphorus, respectively,
present as tetrahedral oxides, said mole fractions being such that
they are within the pentagonal compositional area defined by points
A, B, C, D and E 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
C, F, J, N, P, U and V;
the process comprising providing a reaction mixture composition
to 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 "w", "u"
and "v" represent the mole fractions, respectively, of
germanium, aluminum and phosphorus in the (Ge.sub.w Al.sub.u P.sub.v)O.sub.2
constituent, and each has a value of at least 0.01.
14. The process of claim 13 wherein "w", "y"
and "z" are within the pentagonal compositional area defined
by points F, G, H, I and J of FIG. 3.
15. The process of claim 13 wherein "a" is in the range
of greater than zero to about 6.
16. The process of claim 13 wherein "a" is not greater
than about 0.6.
17. The process of claim 13 wherein "b" is not greater
than about 60.
18. Process according to claim 13 wherein the reaction mixture
comprises from about 0.2 to about 0.4 moles of GeO.sub.2 per mole
of P.sub.2 O.sub.5.
19. Process according to claim 13 wherein the reaction mixture
comprises rom about 0.75 to about 1.25 moles of Al.sub.2 O.sub.3
per mole of P.sub.2 O.sub.5.
20. Process according to claim 13 wherein the source of phosphorus
in the reaction mixture is orthophosphoric acid.
21. Process according to claim 20 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.
22. Process according to claim 21 wherein the aluminum alkoxide
is aluminum isopropoxide or aluminum sec-butoxide.
23. Process according to claim 13 wherein the source of aluminum
is aluminum chlorhydrol.
24. Process according to claim 13 wherein the source of germanium
is selected from the group consisting of oxides, alkoxides, hydroxides,
chlorides, bromides, iodides, nitrates, sulfates, carboxylates and
mixtures thereof.
25. Process according to claim 24 wherein the source of germanium
is selected from the group consisting of germanium dioxide, germanium
ethoxide and germanium tetrachloride.
26. Process according to claim 13 or 14 wherein the organic templating
agent is a quaternary ammonium or quaternary phosphonium compound
having 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.
27. Process according to claim 13 wherein the organic templating
agent is an amine.
28. Process according to claim 13 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; pyrroldine; 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 has a value of at least 2.
Molecular sieve description
FIELD OF THE INVENTION
The instant invention relates to a novel class of crystalline microporous
molecular sieves and to the method of their preparation. The invention
relates to novel germanium-aluminum-phosphorus-oxide molecular sieves
containing framework tetrahedral oxide units of germanium, aluminum
and phosphorus. These compositions may be prepared hydrothermally
from gels containing reactive compounds of germanium, 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 alumino-silicate 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 alumino-phosphate 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 alumino-phosphates 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 alumino-phosphates 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 Fe.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
comprising framework tetrahedral units of GeO.sub.2 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 germanium-aluminum-phosphorus-oxide
molecular sieves having a crystal framework structure of GeO.sub.2
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 GeO.sub.2 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
(Ge.sub.x Al.sub.y P.sub.z)O.sub.2 and has avalue of zero to about
0.3; and "x", "y" and "z" represent
the mole fractions of germanium, aluminum and phosphorus, respectively,
present as tetrahedral oxides. These molecular sieve compositions
comprise crystalline molecular sieves having a three-dimensional
microporous framework structure of GeO.sub.2 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 "GeAPO" to designate the framework
of GeO.sub.2 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 GeAPO class by assigning a
number and, accordingly, are identified as "GeAPO-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.
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 used in the synthesis of conventional zeolite
alumino-silicates. 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 compounds and quaternary ammonium compounds,
the latter two 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 GeAPOs 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. to every templating agent will direct the formation
of every species of GeAPO, i.e., a single templating agent can,
with proper manipulation of the reaction conditions, direct the
formation of several GeAPO compositions, and a given GeAPO 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 isopropoxide, aluminum sec-butoxide or pseudoboehmite.
Aluminum chlorhydrol (Al.sub.2 Cl(OH).sub.5.2H.sub.2 O) may also
be employed. 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 germanium can be introduced into the reaction
system in any form which permits the formation in situ of a reactive
form of germanium, i.e., reactive to form the framework tetrahedral
oxide unit of germanium. Compounds of germanium which may be employed
include oxides, alkoxides, hydroxides, chlorides, bromides, iodides,
nitrates, sulfates, carboxylates, organo-germanium compounds and
the like. Especially preferred sources of germanium are germanium
tetrachloride, germanium ethoxide and germanium dioxide.
As illustrated in some of the Examples below, in some cases it
may be advantageous, when synthesizing the GeAPO compositions of
the present invention, to first combine germanium and aluminium
sources to form a mixed germanium aluminum compound, typically a
mixed germanium aluminum oxide, and thereafter to combine this mixed
germanium aluminum compound with a source of phosphorus to produce
the final GeAPO composition.
While not essential to the synthesis of GeAPO compositions, stirring
or other moderate agitation of the reaction mixture and/or seeding
the reaction mixture with seed crystals of either the GeAPO species
to be produced or a topologically similar aluminophosphate, aluminosilicate
or molecular sieve composition, facilitates the crystallization
procedure.
After crystallization the GeAPO product may be isolated and advantageously
washed with water and dried in air. The as-synthesized GeAPO 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 GeAPO 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 GeAPO product and must be
removed by calcining the GeAPO 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 GeAPO 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 GeAPO phase wherein the organic moiety occupying
the intracrystalline pore system as a result of the hydrothermal
crystallzation 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 germanium, 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 GeAPO material.
Since the present GeAPO compositions are formed from GeO.sub.2
AlO.sub.2 and PO.sub.2.sup.+ tetrahedral units which, respectively,
have a net charge of 0 -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 germanium present in the reaction
mixture, or an organic cation derived from the templating agent.
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, DC (1971)].
The GeAPO 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 GeAPO
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 GeAPO 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 GeAPO
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 GeAPO 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
GeAPO 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. Flat compressed powder samples 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 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 copper K-alpha radiation with Siemens K-805 X-ray sources
with computer based techniques using Seimens 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 reported value of 2 theta. This uncertaity 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, calcination
appears to cause more substantial distortions in the crystal lattice,
and hence more significant changes in the X-ray powder diffraction
pattern.
PROCESS APPLICATIONS
The GeAPO 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 GeAPOs 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 GeAPO 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)
and used, for example, in fabricating catalyst compositions having
silica or alumina bases. The pore diameters of the GeAPO compositions
range from less than 3.46.ANG. to greater than 6.2.ANG.; those species
having pores larger than about 4.ANG. are preferred for catalytic
applications.
Among the hydrocarbon conversion reactions catalyzed by GeAPO 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 GeAPO 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 GeAPO 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 preferably
300.degree. F. to 550.degree. F. (149.degree. C. to 288.degree.
C.) with 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 GeAPO 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.degree. to 750.degree. F. (204.degree.
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 GeAPO
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.), 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 GeAPO 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., organo-nitrogen 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 GeAPO 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 GeAPO 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. |