Note: Descriptions are shown in the official language in which they were submitted.
~19t~Z/j~
1936-1536
A METHOD OF DEHYDROCYCI,IZING ALKANES
BACKGROUND OF T}l _ NVENTION
The invention relates to a new catalyst and a new method of
dehydrocyclizing acrylics more particularly dehydrocyclizing alkanes
containing at least 6 carbon atoms to form the corresponding aromatic
hydrocarbons.
Catalytic reforming is well known in the petroleum industry
and reEers to the treatment of naphtha fractions to improve the octane
rating. The more important hydrocarbon reactions occurring d~lring reforming
operation include dehydrogenation of cyclohe~anes to aromatics, dehydro-
isomeriæation of alkylcyclopentanes to aromatics, and dehydrocyclization
of parafEins to aromatics. Hydrocracking reactions which produce high
yields of light gaseous hydrocarbons, e.g., methane, ethane, propane and
butane, are to be particularly minimized during reforming as this decreases
the yield of gasoline boiling products.
Dehydrocyclization is one of the main reactions in the
reforming process. The conventional methods of performing these dehydro-
cyclization reactions are based on the use of catalysts comprising a noble
metal on a carrier. Known catalysts oE this kind are based on alumina
; ~ 20 carrying 0.2% to 0.8% by weight of platinum and preferably a second
auxiliary metal.
The possibility of using carriers other than alumina has also
been studied and it was proposed to use certain molecular sieves such as X
and Y zeolites, which appeared suitable provided that the reactant and
product molecules were sufficiently small to pass through the pores of the
zeolite. However, catalysts based upon these molecular sieves have not been
commercially successful.
ln the conventional method of carrying out the aforementioned
dehydrocyclization, paraffins to be converted are passed over the catalyst,
in the presence of hydrogen, at temperatures of the order of 500C and
pressures of from 5 to 30 bars. Part of the paraffins are
-- 1 --
~,~
:~9~0~7
converted into aromatic hydrocarbons, and the reaction is accompanied by
isomeriæation and cracking reactions which also convert the paraEfins into
isoparaffins and lighter hydrocarbons.
The rate of conversion of the hydrocarbons into aromatic
hydrocarbons varies with the reaction conditions and the nature of the
catalyst.
The catalysts hitherto usecl have given moderately satisfactory
results w:lth heavy paraffins, but less satisfactory results wLth C6-C8
paraffins, particularly C6 paraffins. Catalysts based on a type 1 zeolite
are more selective with regard to the dehydrocyclization reaction; can be
used to improve the rate of conversion to aromatic hydrocarbons without
requiring higher temperatures, which usually have a considerable adverse
effect on the stability of the catalyst; and produce excellent results
with C6-C8 paraffins. However, run length and regenerability are
problems and satisEactory regeneration procedures are not known~
In one method of dehydrocyclizing aliphatic hydrocarbons,
hydrocarbons are contacted in the presence of hydrogen with a catalyst
consisting essentially of a type L zeolite having exchangeable cations
of which at least 90% are alkali metal ions selected from the group
consisting of ions of sodium, lithium, potassium, rubidium and cesium
and containing at least one metal selected from the group which consists
of metals of Group VIII of the Periodic Table of Elements, tin and germanium,
said metal or metals includi~g at least one metal from Group VIII of
said Periodic Table having a dehydrogenating effect, so as to convert
at least part of the feedstock into aromatic hydrocarbons.
A particularly advantageous embodiment of this method is a
platinum/alkali metal/type L ~eolite catalyst because of its excellent
activity and selectivity for converting hexanes and heptanes to aromatics,
but run length remains a problem.
-- 2 --
~3~ '7
SUMM~RY OF THE INVENT:[ON
__ _ _
The present invention overcomes the deficiencies of the
prior art by using a catalyst comprising a large-pore zeolite, an alkaline
earth metal and a Group VIII metal to reform hydrocarbons at an extremely
high selectivity for converting alkanes to aromatics. The hydrocarbons
are contacted with a catalyst comprising a ]arge-pore æeolite, at least
one Group VIII metal(preferably platinum), and an alkaline earth metal
selected from the group consisting oE barium, strontium and calcium
(preferably varium). In one aspect of the present invention, the process
conditions are afljusted so that the selectivity for n-hexane dehydro-
cycllzation is greater than 60%. In another aspect, the Selectivity Index
of the catalyst is greater than 60%. The catalyst gives satisfactory
run length.
Preferably, the large pore zeolite is a type L zeolite
which contains from 0.1% to 5% by weight platinum and 0.1% to 35% by
weight barium. The hydrocarbons are contacted with the barium-exchanged
type zeolite at a temperature of from 400C to 500C (preferably 430C to
550C); an LHSV of from 0.3 to 5; a pressure of from 1 atmosphere to
500 psig ~preferably from 50 to 300 psig); and an H2/HC ratio of from
1:1 to 10:1 (preferably from 2:1 to 6:1).
DF,SCRIPTION OF THE PREFERRED EMBODIMENTS
In its broadest aspect, the present invention involves the
use of a catalyst comprising a large-pore zeolite, an alkaline earth metal
and a Group VIII metal in the reforming of hydrocarbons, in particular,
the dehydrocyclization of alkanes, at an extremely high selectivity for
converting hexanes to aromatics.
The term "selectivity" as used in the present invention is
defined as the percentage of moles of paraffin converted to aromatics relative
to moles converted to aromatics and cracked products,
100 x moles of paraffins
i.e., Selectivity = converted to arom tics _ _
moles of paraffins converted to
aromatics and cracked products
i' .
:~~
Isome-rization reactions and alkylcyclopentane formation are not
considered in determining selectivity.
The term "selectivity for n-hexane" as used in the present
invention is defined as the percentage of moles of n-hexane converted to
aromatics relative to moles converted to aromatics and cracked products.
The selectivity for converting paraffins to aromatics is a
measure of the efficiency oE the process in converting paraEfins to the
desired and valuable products: aromatics and hydrogen, as opposed to the
less desirable productsof hydrocracking.
An inherent characteristic of any dehydrocyclization catalyst
is its ~electivity Index. The Selectivity Index is defined as the "selectivity
for n~hexane" using n-hexane as feed and operating at 490C, 100 psig, 3 LElSV
and 3 H2/HC after 20 hours.
Highly selective catalysts produce more hydrogen than less
selective catalysts because hydrogen is produced when paraffins are converted
to aromatics and hydrogen is consumed when paraffins are converted to cracked
products. Increasing the selectivity of the process increases the amount of
hydrogen produced (more aromatization) and decreases the amount of hydrogen
consumed (less cracking).
Another advantage of using highly selective catalysts is that the
hydrogen produced by highly selective catalysts is purer than that produced
by less selective catalysts. This higher purity results because more hydrogen
is produced, while less low boiling hydrocarbons (cracked products) are
produced. The purity of hydrogen produced in reforming is critical if, as is
usually the case in an integrated refinery, the hydrogen produced is utilized
in processes such as hydrotreating and hydrocracking, which require at least
certain minimum partial pressures of hydrogen. If the purity becomes too low,
the hydrogen can no longer be used for this purpose and must be used in a less
valuable way, for example as fuel gas.
',~
'7
In the method according to the invention, the feed hydrocarbons
preferab:ly comprise nonaromatic hydrocarbons containing at least 6 carbon
atoms. Preferably, the feedstock is substantially free of sulfur, nitrogen,
metals and other known poisons for reforming catalysts.
The dehydrocyclization is carried out in the presence of
hydrogen at a pressure adjusted so as to favor the reaction thermodynamically
and limit undesirable hydrocracking reactions by kinetic means. The
pressures used preferably vary from 1 atmosphere to 500 psig, more preferably
from 50 to 300 psig, the molar ratio of hydrogen to hydrocarbons
preferably being from 1:1 to 10:1, more preferably from 2:1 to 6:1.
In the temperature range of from ~l00C to 600C, the
dehydrocyclization reaction occurs with acceptable speed and selectivity.
If the operating temperature is below 400C, the reaction
speed is insufficient and consequently the yield is too low for industrial
purposes. Also, the dehydrocyclization equilibria is unfavourable at low
temperatures. When the operating temperature is above 600C, interfering
secondary reactions such as hydrocracking and coking occur, and sub-
stantially reduce the yield and increase the catalyst deactivation rate.
It is not advisable, therefore, to exceed the temperature of 600C.
The preferred temperature range (~30C to 550C) of
dehydrocyclization is that in which the process is optimum with regard to
activity, selectivity and the stability of the catalyst.
The liquid hourly space velocity of the hydrocarbons is
preferably between 0.3 and 10.
The catalyst according to the invention is a large-pore zeolite
charged with one or more dehydrogenating constituents. The term "large-
pore zeolite" is defined as a zeolite having an effective pore diameter of
6 to lS Angstroms.
Among the large-pored crystalline zeolites which have been
found to be useful in the practice of the
- 5 -
,L, ' :,
2'~'
--6~
present lnventlon, type L zeolite and syn-thetic zeolites
having the faujaslte structure such as zeolite X and zeolite Y
are the most important and have apparent pore sizes on the
order of 7 to 9 Angstroms.
A con:~position o:f type L zeolite, expressed in terms
of mole ratios of oxides, may be represen ted as follows
(0.9-1.3)M2/nO:A12O3(5.2 6.9)SiO2:y 2
wherein M designates a cation, n represents the valence of
M, and y may be any value from 0 to about 9. Zeoli te L, its
X-ray diffraction pattern, its properties, and method for its
preparation are described in detail in Uni-ted States Pa-tent
No. 3,216,789. United States Patent No. 3,216,789 descrihes
the preferred zeolite of the present invention. The real
formula may vary without changing the crystalline struc-ture;
for example, the mole ratio of silicon to aluminum (Si/Al) may
vary from 1.0 to 3.5.
The chemical formula for zeolite Y expressed in
terms of mole ratios of oxides may be written as:
(0.7-l.l)Na2O:A12O3:xsiO2:YH2O
wherein x is a value greater than 3 up to about 6 and y may be
a value up to about 9. Zeolite Y has a characteristic X-ray
powder diffraction pattern which may be employed with the
above formula for identification. Zeolite Y is described in
more detail in United States Patent 21O. 3,130,007. United
States Patent No. 3,130,007 describes a l~eolite useful in -the
present invention.
Zeolite X is a synthetic crystalline zeolitic
molecular sieve which may be represented by the formula:
(0.7-l.l)M2/nO.A12O3:(2.0-3)SiO2:y 2
it3~
--7--
wherein M represents a metal, par-ticularly alkali and
alkaline earth metals, n is the valence of M, and y may have
any value up to about 8 depending on the identity of M and the
degree of hydration of the crystalline zeolite. Zeolite Y~,
its X-ray diffraction pattern, its properties, and method ~or
its preparation are described in detail in United States Patent
No. ~,882,244. United States Patent No. 2,~82,2~ describes a
zeolite useEu:L in the present invention.
The preferred catalyst according to the invention is
a type L zeolite charged with one or more dehydrogenating
constituents.
An essential element of the present inven-tion is the
presence of an alkaline earth metal in the large-pore zeolite.
That alkaline earth metal must be either barium, strontium or
calcium, preferably barium. The alkaline earth metal can be
incorporated into the zeolite by synthesis, impregnation or ion
exchange. Barium is preferred to the other alkaline ear-ths
because it results in a somewhat less acidic catalyst. Strong
acidity is undesirable in the catalyst because it promotes
cracking, resulting in lower selectivity.
In one embodiment, at least part of the alkali meta]
is exchanged with barium, using techniques known for ion
exchange of zeolites. This involves contacting the zeoli-te
with a solution containing excess Ba ions. The barium should
constitute from 0.1% to 35% of the weight of the zeolite.
The dehydrocyclization catalysts according to the
invention are charged with one or more Group VIII metals, e.g.,
nickel, ruthenium/ rhodium, palladium, iridium or pla-tinum.
. -7a-
The preferred Group VIII metals are iridium and par-
ticularly platinum, which are more selective with regard to
dehydrocyclization and are also more stable ~mder -the dehydro
cyclizatlon reaction condi-tions -than o-ther Group VIII metals.
The preferred percen-tage of platinum in the ca-talyst
is between 0.1% and 5%.
Group VIII rnetals are introduced in-to the large-pore
zeoli-te by syn-thesis, impregna-tion or exchanye in an aqueous
solution of an appropriate sal-t. When i-t is desired -to
introduce two Group VIII metals in-to -the
~ (3~ ~
zeolite, the operation may be carried out simultcmeously or sequentlally
By way of example, platinum can be introduced by impregnating
the zeolite with an aqueous solution of tetrammineplatinum (II) nitrate,
tetrammineplatinum ~II) hydroxide, dinitrodiamino-platinum or
tetrammineplatinum (II) chloride. In an ion exchange process, platinum can
be introduced by using cationic platinum comp]exes such as tetramrnine-
platinllm (II) nitrate.
An inorganic oxide may be used as a carrier to b-ind the large-
pore zeolite containing the Group VIII metal and alkaline earth metal.
The carrier can be a natural or a synthetically produced inorganic oxide or
combination of inorganic oxides. Typical inorganic oxide supports wl~ich
can be used include clays, alumina, and silica, in which acidic sites are
preferably exchanged by cations which do not impart strong acidity (such
as Na, K, Rb, Cs, Ca, Sr, or Ba).
The catalyst can be employed in any of the conventional types
of equipment known to the art. It may be employed in the form of pills 9
pellets, granules, broken fragments, or various special shapes, disposed
as a fixed bed within a reaction zone, and the charging stock may be passed
therethrough in the liquid, vapor, or mixed phase, and in either upward or
downward flow. Alternatively, it may be prepared in a suitable form for
use in moving beds, or in fluidized-solid processes, in which the charging
stock is passed upward through a turbulent bed of finely divided catalyst.
After the desired metal or metals have been introduced, the
catalyst is treated in air at about 260C and then reduced in hydrogen
at temperatures of from 200C to 700C, preferably 400C to 620C.
At this stage it is ready for use in the dehydrocyclization
process. In some cases however, for example when the metal or metals have
been introduced by an ion exchange process, it is preferable to eliminate
any residual acidity of the zeolite by treating the catalyst
~1 _9~
with an aqueous solution o~ a salt or hydroxide of a suit-
able alkali or alkaline earth element in order to
05 neutralize any hydrogen ions formed during the reduction
of metal ions by hydrogen.
In order to obtain optirnum selectivity,
tempera~ure should be adjusted ~o that reaction rate is
appreciable, but conversion is les.s than 98~, as excessive
temperature and excess reaction can have an adverse affect
on selectivity. Pressure should also be adjusted within a
proper range~ Too high a pressure will place a thermo-
dynamic (equilibrium) limit on the desired reaction,
especially for hexane aromatization, and too low a pres-
sure may result in coking and deactivation,
Although the primary benefit of this inventionis in improving the selectivity for conversion of paraf-
fins (especially C6-C8 paraffins) to aromatics, it is also
surprisingly found that the selectivity for conversion of
methylcyclopentane to benæene is excellent. This reac
tion, which on conventional reforming catalysts based on
chlorided alumina involves an acid catalyzed isomerization
step, occurs on the catalyst of this invention with selec-
tivity as good as or better than on the chlorided alumina
based catalysts of the prior art. Thus, the present
invention can also be used to catalyze the conversion of
stocks high in 5-membered-ring alkyl naphthenes to
aromatics.
Another advantage of this invention is that the
catalyst of the present invention is more stahle than
prior a~t zeolitic catalysts. ~tability of the catalyst,
or resistance to deactivation, determines its useful run
length. Longer run lengths result in less down time and
expense in regenerating or replacing the catalyst charge.
In one embodiment o~ the present invention, a
hydrocarbon feed is contacted with a first catalyst which
is a conventional refor~ing catalyst and a second catalyst
which is a dehydrocyclization catalyst comprising a large-
pore zeolite~ an alkaline eartil metal and a ~roup VI-[ r
metal.
3~i{~
t --10--
The use oE a reEorming catalyst comprising an alumina
support, platinum, and rhenium is cliscussed fully in United
States Patent 3,415,737, whlch describes -the use of an advan-
tageous conventional reforming catalyst. Other advantageous
bimetallic catalysts include platinum--tin, platinum-germanium,
platinum-lead and pla-tinum-iridium.
The hydrocarbons can be contacted with the two cata-
lysts in series, with the hydrocarbons first being contacted
with the first (conventional) reforming catalyst, and then with
the second (dehydrocyclization) catalyst; or with the hydro-
carbons first being contacted wi-th the second catalyst; and
then with the first catalyst. Also the hydrocarbons can be
contacted in parallel with one fraction of the hydrocarbons
being contacted wlth the first catalyst and another fraction
of the hydrocarbons being contac-ted with the second catalyst.
Also the hydrocarbons can be contacted with both catalysts
simultaneously in the same reactor.
EXAMPLES
The invention will be further illustrated by the
following examples which set forth a particularly advantageous
method and composition embodiments. While the examples are
provided to illustrate the present invention, they are not
intended to limit it.
Example I
An Arabian Light straight run which had been hydro-
fined to remove sulfur, oxygen and nitrogen was reformed at
100 psig, 2 LHSV, and 6 H2/HC by three different catalysts.
The feed contained 80.2v~ paraffins, 16.7v~ naphthenes, and
~l~g~
~lOa-
3.1v% aromatics, and it contained 21.8v% C5, 52.9v% C6, ~1.3v%
C7, and 3.2v% C8.
In the first run, the Arabian Light straight run
was reformed at 499C using a commercial sulfided platinum~
rhenium-alumina catalyst discl.osed in United States Patent
No. 3,415,737.
In the second run, the Arabian Light straight run
was reformed at 493~C using a platinum-potassi.um-type
27
L zeolite catalyst formed by~ Lmpregnat:ing a potassium-type I. æeolite
with 0.8% platinum using tetrammineplatinum (Il) nitrate; (2) drying the
catalyst; (3) calcining the catalyst at 260C; and (4) reducing the
catalyst at 480C to 500C for 1 hour.
In the third run, the process of the present invention, the
Ara~ian l.ight straight run was reformed at 493C u.sing a platinum-barium-
type L zeolite catalyst Eormed by: (1) Lon exchanging a potassium-type L
zeolite with a suEficient volume of 0.17 molar barium nitrate solution to
contain an excess of barium compared to the ion exchange capacity of the
zeolite; (2) drying the resulti}lg bar:Lum-exchanged type L zeolite
catalyst; (3) calcining ~he catalyst at 590C; (4) impregnating the
catalyst with 0.8% platinum using tetrammineplatinum (II) nitrate; (5)
drying the catalyst; (6) calcining the catalyst at 260C; and (7)
reducing the catalyst in hydrogen at 480C to 500C for 1 hour.
The results of these three runs are shown in Table I.
TABLE I
499C
Pt/Re 493C 493C
Feed Alumina Pt/K/LPt/Ba/L
__ _ _
Cl Wt % Fd 2.8 5.5 3.6
C2 6.6 2.5 1.3
3 9.3 3.2 1.5
iC4 0.1 5.8 0.9 0.5
NC4 0.5 6.8 3.8 2.4
iC5 5.1 13.6 6.7 5.6
NC5 11.3 9.8 12.6 12.6
C6~ P-~N 81.3 13.4 7.8 9.3
Benzene 1.5 15.1 40.6 43.8
C7+ Aromatics .8 15.8 12.7 15.0
C5~ LV % Yield 63 69.9 74.4
Hydrogen, SCF/B 470 1660 2050
Selectivity,~ole % 20 72 87
C6~ P --> Aromatics
This series of runs shows that the use of a platinum-
barium-type L zeolite catalyst in reforming gives a selectivity for
, ~ ,,
3~
converting hexanes to benzene markedly superior to that of the prior art.
Not:Lce that associated with this superior selectivity is an increase in
hydrogen gas producti.on which can be used in other processes. Notice
also that the hydrogen purity is higher for the Pt/Ba/L run since more
hydrogen is produced and less Cl plus C2 are produced.
EXAMPLF._[I
A second series of runs were made to show that the present
invention would work with other large--pore zeolites in aclditlon to type
L æeolite. The Selectivity Index was measured for four catalysts.
this second ser:ies of runs was made using n-hexane as feed.
All runs in this series were made at 490C, 100 psig, 3 LHSV and 3 H2/HC.
In the first run, a platinum-potassium-type L zeolite was
used which had been prepared by the procedures shown in the second
process of Example I.
In the second run, a platinum-barium-type 1. zeolite was used
which had been prepared by the procedures shown in the third process of
Example I except that the barium nitrate solution was 0.3 molar instead of
0.17 molar.
In the third run, a platinum-sodium-zeolite Y was used which
had been prepared by impregnating a sodium-zeolite Y with Pt(NH3)4(N03)2
to give 0.8% platinum, then drying, calcining the catalyst at 260C and
reducing in hydrogen at 480-500C.
In the fourth run, a pl.atinum-barium-zeolite Y was used which
had been prepared by ion exchangingasodium-zeolite Y with 0.3 molar
barium nitrate at 80C, drying, and calcining at 590C, then impregnating
the æeolite with Pt(NH3)4(N03)2 to give 0.8% platinum, then drying,
calcining the catalyst at 260C, and reducing in hydrogen at 480-500C.
The results of these runs are given below in Table II.
~.
- 12 -
3~ 7
TABIE II
Conver ion Selectivity
` 5 hrs. 20 hrs. Index _
Pt/K/L 70 59 79
Pt/Ba/L 85 85 92
Pt/Na/Y 82 79 54
Pt/Ba/Y 74 68 66
Thus, in operation, the incorporation of barium into a large-
pore zeol:ite, such as type Y zeolite, causes a dramatic improvement in
selectivity for n-hexane. Notice that the stability of the platinum-
barium-type L zeolite is excellent. After 20 hours, there was no drop
in conversion when platinum-barium-type L zeolite catalyst was used.
EXAMPLE III
A third series of runs was made to show the effect of adding
additional ingredients to the catalyst.
This third series of runs was made using a feed, which had
bee~ hydrofined to remove sulphur, oxygen and nitrogen, containing
80.9v% paraffins, 16.8v% naphthenes, and 1.7v% aromatics. The feed also
contained 2.$v% C5, 47.6v% C6, 43.4v% C7 and 6.3v% C8. All runs in this
series were made at 490C, 100 psig, 2.0 LHSV and 6.0 H2/HC.
In the first run, a platinum-sodium-zeolite Y was prepared by
the procedures shown in the third process of Example II.
In the second run, a platinum-barium-zeolite Y was prepared by
the procedures shown in the fourth process of Example II.
In the third run, a platinum-rare earth-æeolite Y was prepared
by impregnating a commercial rare earth zeolite Y obtained Erom Strem
Chemicals Inc. to give 0.8% Pt using Pt~NH3)4(N03)2, then the zeolite was
dried, calcined at 260C and reduced at 480-500C.
In the fourth run, a platinum-rare earth-barium-zeolite Y
was prepared by ion exchanging a commercial Strem Chemicals Inc. rare
earth zeolite Y with a 0.3 molar
.~
;C~2~
~l -14-
Ba(~O3)2 solution at 80C, drying and calcining the
zeolite at 590C, impregnating the zeolite with
05 Pt(NH3)4(NO3)2 to give 0.~ Pt, tilen drying, calcining the
zeolite at 260C, and reducing at 430-500C. The results
of these runs are given below in Table III.
TABLE III
Activity Aromatics
@ 3 Hrs, C5~ Selectivity,
_ Mole ~ of Feed % @ 3 Hrs
P~/Na/Y 36 46
Pt/~a/Y 54 68
Pt/Rare E~rth/Y 22 ~Too Low to
Measure)
Pt/Ba/Rare Earth/Y 36 27
This series oE runs shows that the addition of
~U rare earth to the catalyst has an adverse effect on
selectivity.
Example IV
An Arabian Naphtha which had been hydrofined to
remove sulfur, oxygen and nitrogen was reformed at 100
psig, 3 ~HSV, and 3 H2/HC to produce a C5+ product having
an aromatlcs content of 82 wt % by two different processes.
The feed was a hydrofined Arabian Naphtha containing 67.9
paraffins, 23.7% naphthenes, and 8.4~ aromatics.
Distillation results by D86 method were: start - 203F,
5~-219, 10~-224, 30%-243, 50~-265, 70~-291, 90?~321, 9~-
337, EP 370F.
In the first process, the Arabian ~aphtlla was
reformed at 516C in a reactor using a conventional
reforming catalyst comprising 0.3 Pt, 0.6 Re, 1.0 Cl
(wt %) on alumina. It was presulfided separately.
In the second process, the Arabian Naphtha ~las
reformed at 493C in the same reactor wherein the top half
of the reactor contained the same type of catalyst as t`na.
of the first process and the bottom half of the reactor
contains a platinum-barium-type L zeolite catalyst Eor~e~
by the procedures shown in Example I.
01 -15-
The results of these two runs are shown in
Table IV.
TABLE IV
Pt/Re/1/2 Pt/Re/Alumina
Alumina1/2 Pt/Ba/L
Deactivation Rate 2.0 1.9
C5~ yield r LV~ yield 68.9 71.0
Hydrogen, SCF/D 950 1050
While ~he present invention has been described
with reference to specific embodiments, this application
is intended to cover those various changes and substitu-
~ions which may be made by those skilled in the art with-
out departing from the spirit and scope of the appended
claims.
~)
