PREPARATION OF A BORO-ALUMINO-SILICATE ZEOLITE OF THE ZSM-5 STRUCTURAL TYPE

PREPARATION D'UN ZEOLITE BORO-ALUMINO-SILICATE DE TYPE STRUCTUREL ZSM-5

English Abstract

ABSTRACT OF THE DISCLOSURE:
The present invention is directed to a process for the
preparation of a boro-alumino-silicate zeolite of the ZSM-5
structural type from SiO2, an alkali and an oxide of a trivalent
metal, by hydrothermal crystallization in the presence of an
amine, wherein finely ground low-alkali borosilicate glasses are
used as the starting material. The crystallization is preferably
carried out in the presence of hexamethylenediamine.

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined
as follows:
1. Boro-alumino-silicate zeolite of the ZSM-5
structural type.
2. A process for the preparation of a boro-alumino-
silicate zeolite of the ZSM-5 structural type from SiO2,
an alkali and an oxide of a trivalent metal, by hydro-
thermal crystallization in the presence of an amine,
wherein finely ground low-alkali borosilicate glasses
are used as the starting material.
3. A process as claimed in claim 2, wherein
the crystallization is carried out in the presence of
a diamine.
4. A process as claimed in claim 3, wherein
hexamethylenediamine is used.
5. A process as claimed in claim 2, 3 or 4,
wherein the solids content in the reaction mixture is
greater than 25% by weight.
6. Method for conversion of lower alcohols
and/or dialkyl ethers to hydrocarbons which contain
aromatics and/or to olefins, wherein use is made of the
zeolites as prepared by a process as claimed in claim 2.

Description

~z~s
The preparation of zeolites of the ZSM-5 type
from reaction mixtures which contain SiO2, ~12O3 and
an alkali, under hydrothermal conditions in the
presence of an amine, has been disclosed. SiO2-
containing starting materials are in particular water-
glass, various silicas and silicic acid sols.
Because of the low space-time yield, these
processes are expensive, since the solids content o~
the reaction mixtures is only about 10% by weight.
The crystallizatio~ requires about 5 days.
We have ~ound that in the preparation of a
boro-alumino-silicate zeolite of the ZSM-5 structural
type from SiO2, an alkali and an oxide of a trivalent
metal, by hydrothermal crystallization in the presence
of an amine, a substantial simplification of the
process and improvement of the space-time yield is
achieved if finely ground low-alkali borosilicate
glasses are used as the starting material~
~dvantageously, the process according to the
inv~nkion ia carried out in the presence of a diamine,
especially hexamethylenediamine.
It is surprising~tha-t reaction mixtures with
solids contents of more than 25% by weight can be
crystallized if the reackion is carried out in the
presence of a diamine and a finely ground glass powder
is used as the starting material. Compared to
pyrogenic silica, silicic acid sols or waterglass,
glass is regarded as a relatively inert material. It
was surprising thak glass could be con-

ll~Z~1~5
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verted at all using diamines, which are only weakly
basic, and that using this method the space-time yield
~uldevenbe increased substantially
The process according to the invention can be
: carried out by mixing ~inely ground glass powder with an
aqueous solution o~ an organic diamine, the solids con-
. . tent ad~antageously being more than 25% ~y weight, and
then heating the mixture for from 1 to 10 days at from
100 to 200C under its autogenous pressure, whilst
stirring or shakin~, until crystallization occurs.
The.crystals are separated from the mother liquor, washed
~nd dried Preferably, the process is carried out at
from 140 to 160C 9 with a reaction time of from 2 to 6
days.
The starting materials used are amines, advan-
tageously diamines, for example hexamethylenediamine,
in aqueous solution. Various t~pes oX glass may be
used. Finely ground low-alkali borosilicate glasses
are particularly suitable. In that case, zeolites
which are o~ the boro-alumino-3ilicate type and which
exhibit the crystal structure of the convention~l ZSM-5
aluminosilicate zeolite are obtained.
The zeolites prepared according to the inventicn
contain SiO2 and A1203~ and where appropriate B203, in
various ratios depending on the composition of the
glass used; for example, they may contain SiO2 and
A1203 in a molar ratio or f rom 30:1 to 200:1,
~nd S102 and 323 in a molar ratio of from 3:1 to

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200:1, Dependin~ on the type of glass used7 other com-
ponents may also be present in the zeolite. Sub-
stantial amounts of the amine used may also be accommo-
dated in the inter-crystalline pores, This amine
can be removed from the pores by, ~or example, combustion,
whereby catalytically active materials are produced,
The zeolite may also have an alkali content which varies
depending on the composition of the glass used. The
alkali metal ions can be replaced by protons or other
cations with the aid of conventional ion exchange
techniques,
The zeolites prepared according to the invention
can be used as catalysts for the con~ersion of methanol
and/or dimethyl ether or ethanol or
diethyl ether into aromatic hydrocarbons and/or olefins,
The zeolites can furthermore be used in alkylation re-
actions and isomerization reactions,
The Example which follows illustrates the process
according to the invention,
EXAMPLE
20 . 45 g of a finely ground commercial borosilicate
glass which contains about 80~ by weight of SiO2, 12.9%
by weight of B203 , 2.27% by weight of
A1203 and 3,25% by weight of Na20 are introduced into
118 g of a 50 per cent strength aqueous hexamethylene-
diamine solution and the mixture is heated for 5 days at
150C under autogenous pressure, whilst being stirred,
The crystalline product is filtered off, washed and
dried at 100C~ According to X-ray diffraction

96~5
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analysis, it consists o~ well-crystallized material of
the structural type of the co~ventional ZSM-5 alumino-
silicate zeolite.
Chemical analysis gives the following results:
5,05/0 of B203; 2.420,6 of A1203; 78.70,6 of SiO; 1,69% of
Na~0; remainder hexamethylenediamine/H20,
If, under the same reaction conditions, 60 g of
the same finely ground glass powder are employed in 118 g
of hexamethylenediamine solution9 a 100% crystallized
end product is again obtained.