Molecular sieve abstract
The invention concerns a process for the selective hydroisomerisation
of compounds containing at least one n-alkane chain containing more
than 10 carbon atoms, in which the compound to be treated is brought
into contact with a catalyst comprising at least one hydro-dehydrogenating
element and at least one molecular sieve with a mono- or bidimensional
pore network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, and in which the catalyst, when
subjected to a standard n-heptadecane isomerization test, has a
selectivity of at least 70% towards isomerized products for a conversion
of 95%. The sieve is preferably a NU-10 NU-23 NU-87 EU-13 or
Theta-1 zeolite.
Molecular sieve claims
We claim:
1. A process for the selective hydroisomerisation of compounds
containing at least one n-alkane chain containing more than 10 carbon
atoms, in which said compound to be treated is brought into contact
with a catalyst comprising at least one hydro-dehydrogenating element
and at least one molecular sieve with a mono- or bidimensional pore
network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, the molecular sieve is NU-23 NU-87
or EU-13 and in which said catalyst, when subjected to a standard
n-heptadecane isomerisation test, has a selectivity of at least
70% towards isomerised products for a conversion of 95%.
2. A process according to claim 1 in which the bridge width is
in the range 0.50 nm to 0.68 nm.
3. A process according to claim 1 in which the bridge width is
in the range 0.52 nm to 0.65 nm.
4. A process according to claim 1 in which the molecular sieve
has a crystallite size of less than 2 .mu.m.
5. A process according to claim 1 in which the molecular sieve
has a crystallite size of less than 1 .mu.m.
6. A process according to claim 1 in which the molecular sieve
has a crystallite size of less than 0.4 .mu.m.
7. A process according to claim 1 in which the molecular sieve
is NU-23.
8. A process according to claim 1 in which the molecular sieve
is NU-87.
9. A process according to claim 1 in which the molecular sieve
is EU-13.
10. A process according to claim 1 in which the hydro-dehydrogenating
element is selected from the group consisting of group VIII metals,
group VIB metals, rhenium and niobium.
11. A process according to claim 1 in which the catalyst contains
a matrix, and 0.5-99.9% by weight of molecular sieve, with respect
to the mixture of matrix and sieve, and less than 5% by weight of
hydro-dehydrogenating metal with respect to the sieve.
12. A process according to claim 11 in which the catalyst contains
10%-90% by weight of sieve with respect to the mixture of matrix
and sieve.
13. A process according to claim 1 in which the pressure is in
the range 1 bar to 250 bars, the temperature is in the range 170.degree.
C. to 500.degree. C., the hourly space velocity is in the range
0.05 h.sup.-1 to 100 h.sup.-1 and the hydrogen concentration is
in the range 50 liters to 2000 liters of hydrogen/liters of feed.
14. A process according to claim 13 in which the temperature is
in the range 180-450.degree. C.
15. A process according to claim 14 in which the pressure is in
the range 10 bars to 200 bars.
16. A process according to claim 15 in which the hydrogen concentration
is in the range 100 liters to 1500 liters of hydrogen/liter of feed.
17. A process according to claim 1 in which the compound to be
treated in selected from the group consisting of n-alkanes, n-alkylcycloalkanes
and compounds containing at least one aromatic group.
18. A process according to claim 1 in which the compound to be
treated is present in a feed with an initial boiling point of more
than 175.degree. C.
19. A process according to claim 1 in which the compound to be
treated is present in a feed with an initial boiling point of at
least 380.degree. C.
20. A process according to claim 1 in which the compound to be
treated comprises an n-alkane chain containing 15 to 50 carbon atoms.
21. A process according to claim 1 in which the compound to be
treated comprises an n-alkane chain containing 15 to 40 carbon atoms.
22. A process according to claim 1 in which the compound to be
treated is present in a hydrocarbon feed selected from the group
formed by middle distillates, vacuum residues, hydrocracking residues,
paraffins from the Fischer-Tropsch process, synthesised oils, gas
oil cuts, middle distillates from FCC, lubricant stocks, and polyalphaolefins.
23. A process for the selective hydroisomerisation of compounds
containing at least one n-alkane chain containing more than 10 carbon
atoms, in which said compound to be treated is brought into contact
with a catalyst comprising at least one hydro-dehydrogenating element
and at least one molecular sieve with a mono- or bidimensional pore
network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, the molecular sieve is Nu-23 Nu-87
or Eu-13 and contains boron, gallium or zinc, and in which said
catalyst, when subjected to a standard n-heptadecane isomerisation
test, has a selectivity of at least 70% towards isomerised products
for a conversion of 95%.
24. A process for the selective hydroisomerisation of compounds
containing at least one n-alkane chain containing more than 10 carbon
atoms, in which said compound to be treated is brought into contact
with a catalyst comprising at least one hydro-dehydrogenating element
and at least one molecular sieve with a mono- or bidimensional pore
network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, the molecular sieve is Eu-13 and
in which said catalyst, when subjected to a standard n-heptadecane
isomerisation test, has a selectivity of at least 70% towards isomerised
products for a conversion of 95%.
25. A process according to claim 24 wherein the molecular sieve
contains B, Ga or Zn.
26. A process for the selective hydroisomerisation of compounds
containing at least one n-alkane chain containing more than 10 carbon
atoms, in which said compound to be treated is brought into contact
with a catalyst comprising at least one hydro-dehydrogenating element
and at least one molecular sieve with a mono- or bidimensional pore
network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, the molecular sieve is Nu-10 containing
boron, and in which said catalyst, when subjected to a standard
n-heptadecane isomerisation test, has a selectivity of at least
70% towards isomerised products for a conversion of 95%.
Molecular sieve description
BACKGROUND OF THE INVENTION
The present invention concerns a process for selective hydroisomerisation
of long (more than 10 carbon atoms), linear and/or slightly branched
paraffins, in particular for high yield conversion of feeds with
high pour points to at least one cut with a low pour point and a
high viscosity index.
High quality lubricants are of fundamental importance for the efficient
operation of modern machines, cars and trucks. However, the quantity
of paraffins which directly originate from untreated crude and which
have the properties to constitute good lubricants is very low when
compared with the increasing demand in this sector.
Heavy oil fractions containing large amounts of linear or slightly
branched paraffins must be treated to obtain good quality lubricant
stock in the best possible yields. A dewaxing operation is used
which is intended to eliminate the linear or very slightly branched
paraffins from feeds which are then used as lubricant stock or as
kerosine or jet fuel.
The linear or very slightly branched high molecular weight paraffins
which are present in the oils, kerosine or jet fuel produce high
pour points and thus lead to coagulation at low temperatures. To
reduce the pour points, these linear or very slightly branched paraffins
must be completely or partially eliminated.
The dewaxing operation can be effected by extraction using solvents
such as propane or methyl ethyl ketone, using propane or methyl
ethyl ketone (MEK) dewaxing. However, such techniques are costly,
long and not always easy to carry out.
Catalytic dewaxing, as opposed to solvent dewaxing, is more economical
and can produce products with the desired physico-chemical properties.
This is achieved by selective cracking of the longest linear paraffin
chains which leads to the formation of lower molecular weight compounds,
a portion of which can be eliminated by distillation.
Because of their form-selectivity, zeolites are among the most
widely used dewaxing catalysts. The idea that anticipated their
use is that zeolite structures exist in which the pore openings
are such that they allow long linear or very slightly branched paraffins
to enter their microporosity but branched paraffins, naphthenes
and aromatics are excluded. This phenomenon thus leads to selective
cracking of linear or very slightly branched paraffins.
Zeolite based catalysts with intermediate pores such as ZSM-5
ZSM-11 ZSM-12 ZSM-22 ZSM-23 ZSM-35 and ZSM-38 have been described
for use in catalytic dewaxing by cracking.
Processes using those zeolites can achieve dewaxing by cracking
of feeds containing quantities of less than 50 weight % of linear
or very slightly branched paraffins. However, with feeds containing
higher quantities of these compounds, cracking leads to the formation
of large quantities of lower molecular weight compounds such as
butane, propane, ethane and methane, which considerably reduces
the yield of the desired products.
In order to overcome these problems, we have concentrated our research
on the development of catalysts (preferably non ZSM) which could
bring about isomerisation of these compounds.
A number of patents exist in this field, for example International
patent application WO 92/01657 which describes and claims a process
for dewaxing feeds with isomerisation in the presence of a group
VIII metal at a hydrogen pressure in the range 100 KPa to 21000
KPa and using a catalyst with a pore opening in the range 0.48 nm
to 0.71 nm and in which the crystallite size is less than 0.5 .mu.m.
The catalyst leads to improved performances as regards yield with
respect to prior art catalysts.
SUMMARY OF THE INVENTION
The invention provides a process for the selective hydroisomerisation
of compounds containing at least one n-alkane chain containing more
than 10 carbon atoms, in which the compound to be treated is brought
into contact with a catalyst comprising at least one hydro-dehydrogenating
element and at least one molecular sieve with a mono- or bidimensional
pore network in which the openings of the accessible pores are delimited
by 10 oxygen atoms, and the distance termed the bridge width between
the pores is less than 0.70 nm, and in which the catalyst, when
subjected to a standard n-heptadecane isomerisation test, has a
selectivity of at least 70% towards isomerised products for a conversion
of 95%.
Advantageously, the process can convert a feed with a high pour
point to a mixture with a lower pour point and a high viscosity
index.
The feed also comprises linear and/or slightly branched paraffins
containing at least 10 carbon atoms, preferably 15 to 50 carbon
atoms and advantageously 15 to 40 carbon atoms.
The process comprises the use of a catalyst comprising at least
one molecular sieve having at least one pore type which has an opening
delimited by 10 oxygen atoms and which are the largest type of pore
in the structure which is accessible from the exterior. The pore
network of the zeolite is mono- or bidimensional, preferably monodimensional.
The bridge width between two pore openings (of 10 oxygen atoms),
as defined above, is less than 0.70 nm (1 nm=10.sup.-9 m), preferably
in the range 0.50 nm to 0.68 nm, more preferably in the range 0.52
nm to 0.65 nm. The crystallite size is preferably less than 2 .mu.m
(1 .mu.m=10.sup.-5 m), advantageously less than 1 .mu.m and preferably
0.4 .mu.m.
The catalyst is also characterized in that, for a conversion of
the order of 95% by weight of n-heptadecane (n-C17), it results
in a selectivity towards isomerised products of 70% or more, preferably
at least 80%, under a standard n-C17 isomerisation test (SIT) which
will be described below. The isomerised products generally contain
between about 65% and 80% by weight of monobranched products and
between about 20% and 35% by weight of multibranched products, essentially
dibranched products. The term "monobranched products"
denotes linear paraffins containing a single methyl group, and the
term "dibranched products" denotes linear paraffins containing
2 methyl groups which are not carried by the same carbon atom. Multibranched
products can also be defined by extension. The hydroisomerisation
is thus selective.
The catalyst also comprises at least one hydro-dehydrogenating
function, for example a group VIII metal and/or a group VIB metal
and/or rhenium and/or niobium, and the reaction is carried out under
the conditions described below.
We have surprisingly discovered that one of the determining factors
in obtaining high selectivities towards isomerised products is the
use of molecular sieves which are characterized in that
the opening of the largest pores is delimited by 10 oxygen atoms;
the bridge width must be less than 0.70 nm, preferably in the range
0.50 nm to 0.68 nm, more preferably in the range 0.52 nm to 0.65
nm.
This last point in particular is in contradiction to that claimed
in the prior art patents cited above such as International application
WO 92/01657 which has an essential feature a range of pore sizes
to produce good yields of isomerised products.
The bridge width is measured using a molecular modelling and drawing
method such as Hyperchem or Biosym which can construct the surface
of the molecular sieves concerned and measure the bridge width using
the ionic radii of the elements present in the sieve framework.
The use of the molecular sieves of the invention under the conditions
described above can produce products with a low pour point and a
high viscosity index in good yields.
DETAILED DESCRIPTION OF THE INVENTION
Molecular sieves of the invention which can be used for the isomerisation
of linear or slightly branched paraffin hydrocarbons are zeolites,
crystallised aluminosilicates such as Theta-1 NU-10 NU-23 EU-13
where the Si/Al ratio is best suited for the desired application.
Also among zeolites of the invention is NU-87 zeolite which definitely
has pores delimited by 10 and 12 oxygen atoms but where accessibility
to the latter is via the pore openings with 10 oxygen atoms. Derivatives
of the zeolites described above comprising at least one heteroatom
in the zeolitic framework such as B, Fe, Ga or Zn are also included
in the scope of the invention.
NU-10 zeolite used in the process of the invention and its synthesis
method are described in European patent EP-A-0 077 624. That NU-10
zeolite is characterized by the following X ray diffraction table:
______________________________________ X ray diffraction table
for NU-10 zeolite d(A) I/I.sub.0 ______________________________________
10.95 .+-. 0.25 m to S 8.80 .+-. 0.14 w to m 6.99 .+-. 0.14 w to
m 5.41 .+-. 0.10 w 4.57 .+-. 0.09 w 4.38 .+-. 0.08 VS 3.69 .+-.
0.07 VS 3.63 .+-. 0.07 VS 3.48 .+-. 0.06 m to S 3.36 .+-. 0.06 w
3.31 .+-. 0.05 w 2.78 .+-. 0.05 w 2.53 .+-. 0.04 m 2.44 .+-. 0.04
w 2.37 .+-. 0.03 w 1.88 .+-. 0.02 w ______________________________________
w=weak (l/l.sub.0 between 0 and 20); m=medium (l/l.sub.0 between
20 and 40); S=strong (l/l.sub.0 between 40 and 60); VS=very strong
(l/l.sub.0 between 60 and 100).
NU-10 zeolite has a Si/Al atomic ratio in the range 8 to 1000.
It has been observed that the catalysts of the invention can be
characterized in a catalytic test known as a standard isomerisation
test (SIT) using pure n-heptadecane which is carried out at a partial
pressure of 150 kPa of hydrogen and at a partial n-C17 pressure
of 0.5 kPa, i.e., a total pressure of 150.5 kPa in a fixed bed and
at a constant n-C17 flow rate of 15.4 ml/h using a catalyst mass
of 0.5 g. The reaction is carried out in downflow mode. The degree
of conversion is regulated by the temperature at which the reaction
is carried out. The catalyst subjected to this test is constituted
by pure pelletized zeolite and 0.5% by weight of platinum.
The sieve generally contains at least one hydro-dehydrogenating
element, for example at least one group VIII metal, preferably at
least one metal selected from the group formed by Pt or Pd, which
is introduced into the molecular sieve by dry impregnation or ion
exchange, for example, or using any other method which is known
to the skilled person.
The concentration of hydro-dehydrogenating metal(s) introduced,
expressed as the % by weight with respect to the mass of molecular
sieve used, is generally less than 5% (0.01-5%), preferably less
than 1% (0.01-1%) and generally of the order of 0.5% by weight.
Under these conditions, a molecular sieve of the invention must
produce, for a degree of conversion of n-C17 of the order of 95%
by weight (the degree of conversion is regulated by the temperature)
a selectivity towards isomerised products of 70% by weight or more,
preferably at least 80% by weight.
The isomerisation selectivity in the standard n-C17 isomerisation
test (SIT.sub.n-C17) is defined as follows: ##EQU1## leading to
a n-C17 conversion of the order of 95%.
C.sub.17- products are compounds containing less than 17 carbon
atoms regardless of their degree of branching.
When treating an actual feed, the molecular sieve of the invention
is first formed. In a first variation, the molecular sieve can have
at least one group VIII metal deposited on it, preferably selected
from the group formed by platinum and palladium, and can then be
formed using any technique which is known to the skilled person.
In particular, it can be mixed with a matrix which is generally
amorphous, for example a wet alumina gel powder. The mixture is
then formed, for example by extrusion through a die. The amount
of molecular sieve in the mixture obtained is generally in the range
0.5% to 99.9%, advantageously in the range 10% to 90% by weight
with respect to the mixture (molecular sieve+matrix), preferably
in the range 20% to 70%.
In the following text, the term "support" is used for
the mixture of the molecular sieve+matrix.
Forming can be carried out with matrices other than alumina, such
as magnesia, amorphous silica-aluminas, natural clays (kaolin, bentonite,
sepiolite, attapulgite) and using other techniques such as pelletizing
or bowl granulation.
The hydrogenating group VIII metal, preferably Pt and/or Pd, can
also be deposited on the support using any process which is known
to the skilled person for depositing a metal on a molecular sieve.
A competing cation exchange technique can be used where the competitor
is preferably ammonium nitrate, the competition ratio being at least
about 20 and advantageously about 30 to 200. In the case of platinum
or palladium, a platinum tetramine complex or a palladium tetramine
complex is normally used: these latter are thus practically completely
deposited on the molecular sieve. This cation exchange technique
can also be used to deposit the metal directly onto molecular sieve
powder before any mixing with a matrix.
Deposition of the group VIII metal (or metals) is generally followed
by calcining in air or oxygen, usually between 300.degree. C. and
600.degree. C. for 0.5 to 10 hours, preferably between 350.degree.
C. and 550.degree. C. for 1 to 4 hours. Reduction in hydrogen can
then follow, generally at a temperature in the range 300.degree.
C. to 600.degree. C. for 1 to 10 hours; preferably, in the range
350.degree. C. to 550.degree. C. for 2 to 5 hours.
The platinum and/or palladium can also be deposited not directly
on the molecular sieve but on the alumina binder before or after
the forming step, using anion exchange with hexachloroplatinic acid,
hexachloropalladic acid and/or palladium chloride in the presence
of a competing agent, for example hydrochloric acid. In general,
after depositing the platinum and/or palladium, the catalyst is,
as before, calcined as before then reduced in hydrogen as indicated
above.
Advantageously, the feeds which can be treated using the process
of the invention are fractions with relatively high pour points
which latter it is desired to reduce.
The process of the invention can be used to treat various feeds
from relatively light fractions such as kerosines and jet fuels
up to feeds with higher boiling points such as middle distillates,
vacuum residues, gas oils, middle distillates from FCC (LCO and
HCO) and hydrocracking residues.
The feed to be treated is usually a C10+ cut with an initial boiling
point of more than about 175.degree. C. or a C20+ cut with an initial
boiling point of more than 315.degree. C., preferably a heavy cut
with an initial boiling point of at least 380.degree. C. The process
of the invention is particularly suitable for the treatment of paraffinic
distillates such as middle distillates which include gas oils, kerosines,
jet fuel and all other fractions where the pour point and viscosity
are to be adapted to bring them within specifications.
Feeds which can be treated using the process of the invention can
contain paraffins, olefins, naphthenes, aromatics and also heterocycles,
along with a large proportion of high molecular weight n-paraffins
and very slightly branched high molecular weight paraffins,
The reaction can be carried out such that the degree of cracking
reactions remains sufficiently low to render the process economically
viable. The number of cracking reactions is generally less than
20% by weight.
Typical feeds which can advantageously be treated in accordance
with the invention generally have a pour point above 0.degree. C.,
more usually above 15.degree. C. The products resulting from treatment
in accordance with the invention have pour points of less than 0.degree.
C., preferably less than about -10.degree. C.
These feeds contain more than 30% and up to about 90%, and in some
cases more than 90% by weight of high molecular weight n-paraffins
(n-alkanes) containing more than 10 carbon atoms, and of paraffins
containing more than 10 carbon atoms which are very slightly branched
and also of high molar weight. The process is of particular importance
when this proportion is at least 60% by weight.
Non limiting examples of other feeds which can be treated in accordance
with the invention are bases for lubricating oils, synthesised paraffins
from the Fischer-Tropsch process, polyalphaolefins with high pour
points, synthesised oils, etc. The process can also be applied to
other compounds containing an n-alkane chain as defined above, for
example n-alkylcycloalkane compounds, or containing at least one
aromatic group.
The operating conditions under which the hydroisomerisation of
the invention is carried out are as follows:
the reaction temperature is in the range 170.degree. C. to 500.degree.
C., preferably in the range 180.degree. C. to 450.degree. C., advantageously
180-400.degree. C.;
the pressure is in the range 1 bar to 250 bar, preferably in the
range 10 bar to 200 bar;
the hourly space velocity (vvh, the volume of feed injected per
unit volume of catalyst per hour) is in the range about 0.05 h.sup.-1
to about 100 h.sup.-1 preferably in the range about 0.1 h.sup.-1
to about 30 h.sup.-1.
The feed and the catalyst are brought into contact in the presence
of hydrogen. The quantity of hydrogen used, expressed in liters
of hydrogen per liter of feed, is in the range 50 liters to about
2000 liters of hydrogen per liter of feed, preferably in the range
100 liters to 1500 liters of hydrogen per liter of feed.
The feed to be treated preferably has a nitrogen compound concentration
of less than about 200 ppm by weight, preferably less than 100 ppm
by weight. The sulphur concentration is less than 1000 ppm by weight,
preferably less than 500 ppm, and more preferably less than 200
ppm by weight. The concentration of metals such as Ni or V in the
feed is extremely low, i.e., less than 50 ppm by weight, preferably
less than 10 ppm by weight and more preferably less than 2 ppm by
weight.
The compounds obtained by the process of the invention are essentially
monobranched, dibranched and multibranched with methyl groups. As
an example, in the case of a feed constituted by pure n-heptadecane
(n-C17), methylhexadecane compounds are selectively obtained, mainly
2-methylhexadecane, also the dibranched compounds 27-; 28-; 29-;
210-; and 211-dimethylpentadecane. The total of the isomerised
products represents more than 70% by weight of the products obtained,
with 95% conversion. The isomerised carbon atoms are separated by
a distance of at least the bridge width.
The following examples illustrate the invention without in any
way limiting its scope. They are given for a feed constituted by
n-heptadecane (standard isomerisation test, SIT), or for a hydrocracking
residue.
EXAMPLES
Example 1
Catalyst C1 in Accordance with the Invention
The starting material was a NU-10 zeolite in its H form with a
global Si/Al ratio of about 30 a pore opening delimited by 10 oxygen
atoms and a bridge width, i.e., the distance between two pore openings,
of 0.55 nm. The crystallites of the NU-10 zeolite were in the form
of needles less than 1 .mu.m in length and a width in the range
0. 1 .mu.m to 0.4 .mu.m.
The NU-10 zeolite was dry impregnated with a solution of [Pt(NH.sub.3).sub.4
]Cl.sub.2 to obtain, after calcining and reduction at 450.degree.
C., a Pt content of 0.5% by weight of platinum on the zeolite.
0.5 g of this platinum-charged zeolite, which had been pelletized
(200 .mu.m to 300 .mu.m granulometric fraction) was introduced into
a fixed bed reactor.
The standard n-heptadecane isomerisation test (SIT) was then carried
out at a partial pressure of 150 kPa of hydrogen and a partial pressure
of 0.5 kPa of n-C17 i.e., a total pressure of 150.5 kPa, on a fixed
bed with a constant n-C17 downflow rate of 15.4 ml/h and a catalyst
mass of 0.5 g. The degree of conversion was regulated by the temperature
at which the reaction was carried out.
In this example, the temperature required to achieve 95% by weight
conversion of n-C17 was 190.degree. C. At this temperature, the
selectivity for isomerised products was 93% by weight. The selectivity
is defined as follows: ##EQU2##
The selectivity towards monobranched compounds was 67.4% and for
multibranched compounds it was 25.6%.
Example 2
Catalyst C2 Not in Accordance with the Invention
The starting material was a USY zeolite in its H form with a global
Si/Al ratio of about 5 a pore opening delimited by 12 oxygen atoms
and a bridge width, i.e., the distance between two pore openings,
of more than 0.7 nm.
The USY-H zeolite was dry impregnated with a solution of [Pt(NH.sub.3).sub.4
]Cl.sub.2 to obtain, after calcining and reduction at 450.degree.
C., a Pt content of 0.5% by weight of platinum on the zeolite.
0.5 g of this platinum-charged zeolite, which had been pelletized
(200 .mu.m to 300 .mu.m granulometric fraction) was introduced into
a fixed bed reactor.
The standard n-heptadecane isomerisation test (SIT) was then carried
out at a partial pressure of 150 kPa of hydrogen and a partial pressure
of 0.5 kPa of n-C17 i.e., a total pressure of 150.5 kPa, on a fixed
bed with a constant n-C17 downflow rate of 15.4 ml/h and a catalyst
mass of 0.5 g. The degree of conversion was regulated by the temperature
at which the reaction was carried out.
In this example, the temperature required to achieve 95% by weight
conversion of n-C17 was 220.degree. C. At this temperature, the
selectivity for isomerised products was only 16% by weight. The
selectivity is defined as in Example 1.
The standard isomerisation test is thus a means of selecting catalysts.
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