Molecular sieve abstract
Molecular sieve compositions having three-dimensional microporous
framework structures of BeO.sub.2 AlO.sub.2 PO.sub.2 and SiO.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
(Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2 ; and "w",
"x", "y" and "z" represent the mole
fractions of beryllium, aluminum, phosphorus and silicon, respectively,
present as tetrahedral oxides. Their use as adsorbents, catalysts,
etc. is also disclosed.
Molecular sieve claims
We claim:
1. Crystalline molecular sieves comprising three-dimensional microporous
framework structures of BeO.sub.2 AlO.sub.2 PO.sub.2 and SiO.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
(Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2 and has a value of zero
to about 0.3; and "w", "x", "y" and
"z" represent the mole fractions of beryllium, aluminum,
phosphorus and silicon, 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 A to H and J to W:
2. Crystalline molecular sieves according to claim 1 wherein the
mole fractions of beryllium, aluminum, phosphorus and silicon present
as tetrahedral oxides are within the hexagonal compositional area
defined by points a, b, c, d, e and f of FIG. 2.
3. The crystalline molecular sieves according to claim 1 or claim
2 wherein "m" is not greater than about 0.15.
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 A given in claim 1.
5. The crystalline molecular sieves of claim 4 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:
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 B given in claim 1.
7. 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.
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 D 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 E given in claim 1.
10. 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.
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 G given in claim 1.
12. The crystalline molecular sieves of claim 11 wherein the X-ray
powder diffraction pattern set forth in Table G contains at least
the d-spacings set forth in either of the following Tables GA and
GB:
13. 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 H given in claim 1.
14. 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.
15. 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 K given in claim 1.
16. 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 L given in claim 1.
17. The crystalline molecular sieves of claim 16 wherein the X-ray
powder diffraction pattern set forth in Table L contains at least
the d-spacings set forth in the following Table LA:
18. 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 M given in claim 1.
19. 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.
20. 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 O given in claim 1.
21. 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.
22. 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 Q given in claim 1.
23. 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 R given in claim 1.
24. 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 S given in claim 1.
25. 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 T given in claim 1.
26. 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 U given in claim 1.
27. 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.
28. 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 W given in claim 1.
29. Process for preparing crystalline molecular sieves having three-dimensional
framework structures of BeO.sub.2 AlO.sub.2 PO.sub.2 and SiO.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
(Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2 and has a value of zero
to about 0.3; and "w", "x", "y" and
"z" represent the mole fractions of beryllium, aluminum,
phosphorus and silicon, 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 A to H and J to W:
the process comprising 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 the amount of "R" and is an effective amount greater
than zero to about 6; "b" has a value of from zero to
about 500; and "w", "x", "y" and "z"
represent the mole fractions, respectively, of beryllium, aluminum,
phosphorus and silicon in the (Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2
constituent, and each has a value of at least 0.01.
30. Process according to claim 29 wherein "w", "x",
"y" and "z" are within the area defined by points
F, G, H, I and J of FIG. 3.
31. Process according to claim 29 wherein "a" is not
greater than about 0.5.
32. Process according to claim 29 wherein "b" is not
greater than about 20.
33. Process according to claim 29 wherein the source of phosphorus
in the reaction mixture is orthophosphoric acid.
34. Process according to claim 29 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.
35. Process according to claim 34 wherein the aluminum alkoxide
is aluminum isopropoxide.
36. Process according to claim 29 wherein the silicon source is
silica.
37. Process according to claim 29 wherein the silica source is
a tetraalkyl orthosilicate.
38. Process according to claim 29 wherein the source of beryllium
is selected from the group consisting of oxides, hydroxides, alkoxides,
chlorides, bromides, iodides, sulfates, nitrates, carboxylates and
mixtures thereof.
39. Process according to claim 29 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.
40. Process according to claim 29 wherein the organic templating
agent is an amine.
41. Process according to claim 29 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;
qunuclidine; 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.
42. Molecular sieve prepared by calcining, at a temperature sufficiently
high 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 BeO.sub.2
AlO.sub.2 PO.sub.2 and SiO.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
(Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2 and has a value of zero
to about 0.3; and "w", "x", "y" and
"z" represent the mole fractions of beryllium, aluminum,
phosphorus and silicon, 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 A to H and J to W:
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 beryllium-aluminum-phosphorus-silicon-oxide molecular
sieves containing framework tetrahedral oxide units of beryllium,
aluminum, phosphorus and silicon. These compositions may be prepared
hydrothermally from gels containing reactive compounds of beryllium,
aluminum and phosphorus and silicon capable of forming framework
tetrahedral oxides, and preferably at least one organic templating
agent which function 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
fraction 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 BeO.sub.2.sup.-2 AlO.sub.2.sup.-,
PO.sub.2.sup.+ and SiO.sub.2.
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 beryllium-aluminum-phosphorus-silicon-oxide
molecular sieves having a crystal framework structure of BeO.sub.2.sup.-2
AlO.sub.2.sup.-, PO.sub.2.sup.+ and SiO.sub.2 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 BeO.sub.2.sup.-2 AlO.sub.2.sup.-,
PO.sub.2.sup.+ and SiO.sub.2 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
(Be.sub.w Al.sub.x P.sub.y Si.sub.z)O.sub.2 and has a value of zero
to about 0.3; and "w", "x", "y" and
"z" represent the mole fractions of beryllium, aluminum,
phosphorus and silicon, respectively, present as tetrahedral oxides.
These molecular sieve compositions comprise crystalline molecular
sieves having a three-dimensional microporous framework structure
of BeO.sub.2.sup.-2 Al.sub.2.sup.-, PO.sub.2.sup.+ and SiO.sub.2
tetrahedral units. The instant molecular sieve compositions are
characterized in several ways as distinct from heretofore known
molecular sieves, including the aforementioned ternary compositions.
The instant molecular sieves are characterized by the enhanced
thermal stability of certain species and by the existence of species
heretofore unknown for binary and ternary molecular sieves.
The molecular sieves of the instant invention will be generally
referred to by the acronym "BeAPSO" to designate the framework
of BeO.sub.2.sup.-2 AlO.sub.2.sup.-, PO.sub.2.sup.+ and SiO.sub.2
tetrahedral units. Actual class members will be identified by denominating
the various structural species which make up the BeAPSO class by
assigning a number and, accordingly, are identified as "BeAPSO-i"
wherein "i" is an integer. This designation is an arbitrary
one and is not intended to denote structural relationship to another
material(s) which may also be characterized by a numbering system.
DETAILED DESCRIPTION OF THE INVENTION
The instant invention relates to a new class of beryllium-aluminum-phosphorus-silicon-oxide
molecular sieves comprising a crystal framework structure of BeO.sub.2.sup.-2
AlO.sub.2.sup.-, PO.sub.2.sup.+ and SiO.sub.2 tetrahedral oxide
units. These new molecular sieves exhibit ion-exchange, adsorption
and catalytic properties and, accordingly, find wide use as adsorbents
and catalysts.
In forming reaction mixtures 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 two being represented
generally by the formula R.sub.4 X.sup.+ wherein "X" is
phosphorus or nitrogen 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 BeAPSOs 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; and tetrabutylammonium
ions; tetrapentylammonium ions; 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 BeAPSO, i.e., a single templating agent can,
with proper manipulation of the reaction conditions, direct the
formation of several BeAPSO compositions, and a given BeAPSO composition
can be produced using several different templating agents.
The reactive phosphorus source is preferably phosphoric acid, but
organic phosphates such as triethyl phosphate have been found satisfactory,
and so also have 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 do
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.
Almost any reactive silicon source may be employed such that SiO.sub.2
tetrahedral units are formed in situ. The reactive silicon source
may be silica in the form of a silica sol, may be a fumed silica
or may be other conventional sources of silica used in zeolite synthesis
such as reactive solid amorphous precipitated silicas, silica gel,
alkoxides of silicon, tetraalkyl orthosilicates (for example, tetraethyl
orthosilicate), silicic acid, alkali metal silicates and the like.
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 beryllium can be introduced into the reaction
system in any form which permits the formation in situ of a reactive
form of beryllium, i.e., reactive to form the framework tetrahedral
oxide unit of beryllium. Compounds of beryllium which may be employed
include oxides, alkoxides, hydroxides, chlorides, bromides, iodides,
sulfates, nitrates, carboxylates (e.g., acetates) and the like.
While not essential to the synthesis of BeAPSO compositions, stirring
or other moderate agitation of the reaction mixture and/or seeding
the reaction mixture with seed crystals of either the BeAPSO species
to be produced or a topologically similar aluminophosphate, aluminosilicate
or molecular sieve composition, facilitates the crystallization
procedure.
After crystallization the BeAPSO product may be isolated and advantageously
washed with water and dried in air. The as-synthesized BeAPSO generally
contains within its internal pore system at least one form of the
templating agent employed in its formation. Most commonly the organic
moiety derived from an organic template 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
BeAPSO 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 BeAPSO product and must be removed by calcining
the BeAPSO at temperatures of 200.degree. C. to 700.degree. C. to
thermally degrade the organic species. In a few instances the pores
of the BeAPSO 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 are 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 BeAPSO 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 beryllium, aluminum, phosphorous and/or
silicon, 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
BeAPSO material.
Since the present BeAPSO compositions are formed from BeO.sub.2
AlO.sub.2 PO.sub.2 and SiO.sub.2 tetrahedral units which, respectively,
have a net charge of -2 -1 +1 and 0 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
cation of beryllium present in the reaction mixture, or an organic
cation derived from the templating agent. Similarly, a BeO.sub.2.sup.-2
tetrahedron can be balanced electrically by association with PO.sub.2.sup.+
tetrahedra, a cation of beryllium present in the reaction mixture,
a simple cation such as an alkali metal cation, organic cations
derived from the templating agent, or other divalent or polyvalent
metal cations introduced from a 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- respectively
[Flanigen and Grose, Molecular Sieve Zeolites-I, ACS, Washington,
DC (1971)].
The BeAPSO 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 BeAPSO
compositions is ordinarily possible only after the organic moiety
present as a result of synthesis has been removed from the pore
system. Dehydration to remove water present in the as-synthesized
BeAPSO 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 BeAPSO materials will have various
degrees of hydrothermal and thermal stability, some being quite
remarkable in this regard, and will function as molecular sieve
adsorbents and hydrocarbon conversion catalysts or catalyst bases.
In preparing the BeAPSO 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
BeAPSO 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 the diffraction peaks expressed as 2.theta. where .theta.
is the Bragg angle as observed on the strip chart. Intensities were
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 machanical
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 hereinafter in the illustrative examples,
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 such may have one
of the X-ray patterns set forth in the following Tables A through
W, 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 distortion in the crystal lattice,
and hence, more significant changes in the X-ray powder diffraction
pattern.
PROCESS APPLICATIONS
The BeAPSO 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 BeAPSOs
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 BeAPSO 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 and used, for example,
in fabricating catalyst compositions having silica or alumina bases.
Of the general class, those species having pores larger than about
4A are preferred for catalytic applications.
Among the hydrocarbon conversion reactions catalyzed by BeAPSO
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 BeAPSO 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 BeAPSO 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 BeAPSO 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 BeAPSO
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 BeAPSO 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 reactions 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 BeAPSO 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 BeAPSO 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 examples are provided to further illustrate the use
of the BeAPSOs of the invention in one of the processes discussed
above, but are not intended to be limitative of the possible uses
of the BeAPSOs.
EXAMPLE 8
(Cracking tests on BeAPSO-34/BeAPSO-5)
The n-butane cracking activity of the mixture of BeAPSO-34 and
BeAPSO-5 prepared in Example 5 above 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. This reactor was
loaded with the as-synthesized mixture of BeAPSO-34 and BeAPSO-5
which was in the form of particles having sizes of 20-40 U.S. mesh.
The mixture was then calcined in situ by heating from ambient temperature
to 500.degree. C. under helium, and then holding the sample at 500.degree.
C. in air for 1 hour; the weight of the activated mixture in the
reactor was 0.53 grams.
A feedstock comprising a helium/n-butane mixture containing 2 mole
percent of n-butane was then passed through the reactor at a rate
of 50 mL/min. The reactor effluent was analyzed after 10 minutes
of on-stream operation using conventional gas chromatography techniques.
The resultant data showed a pseudo-first-order rate constant (k.sub.A)
of 7.6.
EXAMPLE 9
(Cracking tests on BeAPSO-20)
The n-butane cracking activity of the BeAPSO-20 prepared in Example
7 above was tested in the same way as in Example 8 above, except
that the calcination was effected by heating from ambient temperature
to 500.degree. C. under helium and then holding the sample at 600.degree.
C. in air for 1 hour, and that the weight of the activated mixture
in the reactor was 0.69 gram. The resultant data showed a pseudo-first-order
rate constant of 0.06. |