Note: Descriptions are shown in the official language in which they were submitted.
5~` 9
This invention relates to a new and improved hydro-
carbon reforming process. More particularly, the invention
relates to an improved process which involves utilizing a
catalyst comprising at least one platinum group metal and at least
one halogen component to promote reforming of a hydrocarbon
feedstock.
The use of catalysts comprising minor amounts of at
least one platinum group metal and at least one halogen component
on a major amount of porous support, e.g., alumina, to promote
hydrocarbon reforming is well known. One disadvantage to using
such a catalyst in hydrocarbon reforming is the high sensitivity
such catalysts have to sulfur in the hydrocarbon feedstock.
Special precautions are often necessary to provide a hydrocarbon
feedstock having a suitably low sulfur concentration. For
example, hydrocarbon reforming feedstocks may be subjected to
conventional processing, e.g., hydrodesulfurization, stripping,
distillation and/or other techniques, to reduce sulfur concentra-
tion. In spite of these measures, hydrocarbon having an excess- 1;
ively high sulfur concentration may inadvertently come into
contact with the catalyst and cause a rapid and substantial
decrease in valuable catalytic activity. Processing upsets in
the equipment used to reduce the sulfur concentration of the
hydrocarbon feedstock can lead to such high sulfur feedstock-
catalyst contact ~nd its resultant problems. The problems caused
by such high sulfur feedstock-catalyst contact should desirably
be minimized.
Therefore, one of the objects of the present invention
is to provide an improved process for hydrocarbon reforming
employing a cata~yst including at least one platinum group metal
and at l~ast one halogen component.
:~ 1
. ...
,""~
~ 5~.~3
Another object of the present invention is to provide
a process for reducing the detrimental effects on a hydrocarbon
reforming process employing a catalyst including at least one
platinum group metal and at least one halogen component caused
by contacting such catalyst with a feedstock containing a high
sulfur concentration.
A still further object of the present invention is to
provide a process for reducing the detrimental effects on a hydro-
carbon reforming process employing a catalyst including at least
one platinum group metal and at least one halogen component caused
by contacting such catalyst with a feedstock containing high
sulfur and water concentrations. Other objects and a~vantages of
the present invention will become apparent hereinafter.
An improved process has been found wherein hydrocarbon
is contacted with a catalyst comprising a major amount of a
porous solid support, e.g., alumina, a minor, catalytically
effective amount, preferably about 0.01% to about 3.0% by
weight, of at least one platinum group metal and a minor,
catalytically effective amount, preferably about 0.1~ to about
5% by weight, of at least one halogen component in the presence
of hydrogen at reforming conditions. The improved process
comprises:
1) contacting ~ hydrocarbon feed with a catalyst,
as described hereinabove, in the presence of hydrogen
in at least one reaction zone at hydrocarbon
reforming conditions; the hydrocarbon feed containing
less than about 8 ppm. by weight of sulfurl and
preferably containing less than about 20 ppm
by weight oi water;
~2
2) contacting a hydrocarbon material having an
undesirably high concentration of sulfur, preferably
at least about 10 ppm. by weight of sulfur and
at least about 50 ppm by weight of water in the reaction
zone with the catalyst in the presence of hydrogen
at reforming conditions to produce further reformate
product and cause the catalyst to be contaminated
with an excessive amount of sulfur;
3) adding a sufficient amount of at least one halogen
component to the reaction zone to substantially maintain
or increase the concentration of halogen component on the
catalyst relative to the lowest catalyst halogen
concentration present during step (1), the halogen
addition being continued at least for a time sufficient
to allow the sulfur concentration on the catalyst
to be reduced to within desirable limits; and
4) repeatlng step (1).
In one preferred embodiment, step (3) is carried out at
least partially while the contacting of step (2) continues. That
is, addition of halogen component occurs while the sulfur
contaminated feedstock continues to contact the catalyst in the
presence of hydrogen at reforming conditions. This embodiment
of the present invention has the advantage of using the high sulfur
feedstock in the reforming reaction zone without causing substantial
permanent deactivation of the catalyst. In addition, step (3)
preferably continues for a period of time after low sulfur and
low water hydrocarbon feedstock is again fed to the reaction zone.
-3-
In many instances, for example, hydrogen-rich gases after being
passed through the reaction zone are at least partially
recycled back to the reaction zone. The recycled hydrogen-rich
gas from step (2) may include excessively high concentrations
of sulfur, e.g., as H2S,and water. Such sulfur and water laden
hydrogen-rich gases may continue to contact and contaminate the
catalyst even after low sulfur, low water feedstock is fed to
the reaction zone. In this instance, step (3) is continued,
even though low sulfur, low water hydrocarbon feedstock is fed
to the reaction zone. The concentrations of contaminants, e.g.,
sulfur and water, on the catalyst and in the reaction zone and
hydrogen-rich gas air decrease over a period of time until the
sulfur concentration on the catalyst is within desirable and
predetermined limits.
As noted above,in step (3) the halogen component
concentration on the catalyst is substantially maintained or
increased relative to the lowest catalyst halogen component
concentration present during step (1). In this context,
"substantially maintained" means that the halogen component
concentration in step (3) is controlled so that this concentration
is equal to at least about 50~, preferably at least about ~5%
and more preferably at least about 80%, of the lowest halogen
concentration on catalyst present during step (1). Of course,
the halogen concentration may be increased during step (3).
Such catalyst halogen concentration should preferably be less
than about 500%, more preferably less than about 300~, of the lowest
catalyst halogen concentration present during step (1). In
a preferred embodiment, the catalyst halogen concentration during
step (2j is at least substantially maintained relative to the
; 30 lowest catalyst halogen component concentration present during
step (1). Thus, the catalyst halogen concentration during
step (3), and preferably also during step (2),is
--4--
preferably in the range of about 75% to about 500%, more pre-
ferably about 80% to about 300%, of the lowest catalyst halogen
concentration present during step (1).
In a prefexred embodiment, the amount of halogen
component added to the reaction zone per unit time during step
(3) is increased relative to the amount of halogen added, if any,
during step 11). The high concentration of water often present
in the reaction zone during step (3) causes halogen component to
be stripped from the catalyst. Therefore, an additional halogen
component is added during step (3) to substantially maintain
or increase the catalyst halogen concentration as noted previously.
The process of the present invention is useful, fox
example, when hydrocarbon being fed to a reforming reaction zone
is inadvertently, or otherwise, contaminated with undesirable
amounts of sulfur and water. To illustrate, hydrocarbons which
are to be fed to a reforming reaction zone are often subjected
to hydrodesulfurization and/or stripping and/or other processes and
procedures prîor to being sent to the reforming zone so that
the sulfur content of this hydrocarbon can be reduced to be
compatible with the platinum group metal-containing reforming
catalyst. Operation upsets and/or other process ~ariations in
the sulfur removal system upstream of the reforming reaction zone
may result in a hydrocarbon material having excessive
concentrations of sulfur and water being fed to the reforming
reaction zone. For example, such high water-containing hydro-
:
carbon feedstocks often include at least about 50 ppm. byweight of waterr preferably at least about 100 ppm. by weight
of water. The high sulfur-containing, and high-water-
containing hydrocarbon material contaminates the refol~ning
catalyst with sulfur and causes a rapid and substantial loss
--5--
~ 5~
in catalytic activity. The present process has been found to
be effective to minimize the detrimental effects of such
sulfur catalyst contamination. Thus, in one embodiment, a
sufficient amount of at least one halogen component is added to
the reaction zone while the high sulfur, high water hydrocarbon
material hydrogen contacting continues to maintain and/or
increase the concentration of halogen component on the catalyst.
Such addition is continued for at least a time sufficient to
allow the sulfur concentration on the catalyst to be reduced
to within desirable limits. Steps (2) and (3) are preferably
carried out at a temperature not substantially higher, e.g., no
more than about 30F. higher, than the highest temperature at which
step (1) was carried out. In other words, the temperature within
the reaction zone is preferably not substantially increased during
steps (2) and (3) relative to the highest temperature in such zone
during step (1). If no halogen or an insufficient amount of
halogen is added to the reaction zone, the catalyst halogen concen-
tration will not be substantially maintained, e.g., the halogen
catalyst component will be stripped away by the excessive amounts
of water in the hydrocarbon material, only a substantially reduced
portion of the activity is restored to the reforming catalyst.
On the other hand, sufficient halogen addition during step (3)
provides for recovery of a significantly greater portion of the
activity possessed by the catalyst prior to being contaminated
with sulfur, i.e., in step ~2) of the present process.
The hydrocarbon feed and hydrocarbon material used
in the present process often include hydrocarbon fractions
containing naphthenes and paraffins, e.g., boiling within the
gasoline range. These hydrocarbon feeds and materials used
in steps (1) and (2) may be the same (other than sulfur and
_fi_
.~ ~
water contents) or different. Typically, these hydrocarbon feeds
and materials may comprise about 20% to about 70% by weight of
naphthenes and about 25~ to about 75% by weight of paraffins.
The preferred hydrocarbons for use as feed and hydrocarbon material
consist essentially of naphthenes and paraffins, although in some
cases aromatics and/or olefins may also be present. When aromatics
are included, these compounds often comprise about 5% to about
25% by weight of the total hydrocarbon material. A preferred
class of hydrocarbon feeds includes straight run gasolines,
natural gasolines, synthetic gasolines and the like.
On the other hand, it is frequently advantageous to use as
hydrocarbon feed and material thermally or catalytically
cracked gasolines or higher boilin~ fractions thereof, called
heavy naphthas. Mixtures of straight run and cracked gasolines
can also be used. The gasoline used as hydrocarbon feed and
material may be full boiling range gasoline having an initial
boiling point of about 50F. to about 150F. and an
end boiling point within the range of about 325F. to about
425F., or may be a selected fraction thereof which generally
will be a higher boiling fraction commonly referred to as a
heavy naphtha -- for example, a naphtha boiling in the range
of about C7 to about 400~F. In some cases, it is also advantageous
to use pure hydrocarbons or mixtures of hydrocarbons that have
been extracted from hydrocarbon distillates ~- for example,
a straight chain paraffin -- which are to be converted to
aromatics. It is preferred that at least a portion of the
hydrocarbon feed used in step (1) be treated by conventional
,~ .
--7--
pretreatment methods, e.g., catalytic hydrotreating and/or
various separation procedures, if necessary, to remove sub-
stantially all sulfurous and nitrogenous contaminants therefrom.
Thus, for example, the hydrocarbon feed to be used in step
(1) of the present invention may be substantially completely
desulfurized, i.e., have a sulfur content of less than about
1 ppm. by weight. In an~ event, step (1) of the present
invention involves the use of a hydrocarbon feed having a
sulfur content less than about 8 ppm., preferably less than about
5 ppm. and more preferably less than about 1 ppm., by weight
based on the total hydrocarbon feed. On the other hand,
the hydrocarbon material used in step ~2) of the present process
preferably has a sulfur content of at least about 10 ppm., more
preferably at least about 50 ppm. and still more preferably,
at least about 100 ppm. by weight based on the total hydrocarbon
material. The sulfur contents set forth herein include contribu-
tions from sulfur-containing compounds and are chemically
combined and/or physically mixed with the hydrocarbon feed and
material.
As indicated above, the catalyst utilized in the
present invention comprises a solid porous support, e.g.,
alumina, at least one platinum group metal and at least one
halogen component. It is preferred that the solid porous
support be a material comprising a major amount of alumina having
a surface area of about 25 m.2/gm. to about 600 m.2/gm. or more.
The solid porous support comprises a major proportion, preferably
at least about 80%, and more preferably at least about 90%, by
weight of the catalyst. The preferred catalyst support, or
base, is an alumina derived from hydrous alumina predominating
- 8-
in alumina trihydrate, alumina monohydrate, amorphous hydrous
alumina and mixtures thereof; more preferably, alumina mono-
hydrate, amorphous hydrous alumina and mixtures thereof, which
alumina when formed as pellets and calcined, has an apparent
bulk density of about 0.60 gm./cc. to about 0.85 gm./cc., pore
volume of about 0.45CC./gm. to about 0.70 cC./gm., and surface
area of about 100 m.2/gm. to about 500 m.2/gm. The solid porous
support may contain, in addition, minor proportions of other
well known refractory inorganic oxides such as silica,
zirconia, magnesia and the like. However, the most preferred
support is substantially pure alumina derived from hydrous alumina
predominating in alumina monohydrate, amorphous hydrous alumina
and mixtures thereof.
The alumina support may be synthetically prepared in
any suitable manner and may be activated prior to use by one or
more treatments including drying, calcination, steaming and the
like. Thus, for instance, hydrated alumina in the form of a
hydrogel can be precipitated from an aqueous solution of a
soluble aluminum salt such as aluminum chloride. Ammonium
hydroxide is a useful agent for effecting the precipitation.
Control of the pH to maintain it within the values of about 7
to about 10 during the precipitation is desirable for obtaining
a good rate of conversion. Extraneous ions, such as halide
ions, which are introduced in preparing the hydrogel, can,
if desired, be removed by filtering the alumina hydrogel from
its mother liquor and washing the filter cake with water. Also,
if desired, the hydrogel can be aged, say for a period of several
days. The effect of such aging is to build up the concentration
of alumina trihydrate in the hydrogel. Such trihydrate formation
can also be enhanced by seeding an aqueous slurry of the hydrogel
_g_
6~
with alumina trihydrate crystallites, for example, gibbsite.
The alumina may be formed into macrosize particles
of any desired shape such as pills, cakes~ extrudates, powders,
granules, spheres, and the like using conventional methods.
The size selected for the macrosize particles can be dependent
upon the intended environment in which the final catalyst is
to be used -- as, for example, whether in a fixed or moving
bed reaction system. Thus, for example, where as in the preferred
embodiment of the present invention, the final catalyst is
designed for use in hydrocarbon reforming operations employing
a fixed bed of catalyst, the alumina will preferably be formed
into particles having a minimum dimension of at least about 0.01
inch and a maximum dimension up to about one-half inch or one
inch or more. Spherical particles having a diameter of about
0.03 inch to about 0.25 inch, preferably about 0.03 inch to
about 0.15 inch, are often useful, especially in a fixed bed
reforming operation.
As indicated above, the catalyst utilized in the
present invention also contains a platinum group metal. The
platinum group metals include platinum, palladium, rhodium,
iridium, ruthenium, osmium and the like with platinum being
preferred for use in the present invention. The platinum
group metal, such as platinum, may exist within the final
catalyst at least in part as a compound such as an oxide, sulfide,
halide and the like, ox in the elemental state. The platinum
group metal component preferably comprises abou~ 0.01% to about
3.0~, more preferably about 0.05% to about 1.0%, by weight
of the catalyst, calculated on an elemental basis. Excellent
results are obtained when the catalyst contains about 0.2
to about 0 n 9~ by weight of the platinum group metal.
The platinum group component may be incorporated in
the catalyst in any suitable manner, such as by coprecipitation
or cogellation with the alumina support, ion-exchange with the
alumina support and/or alumina hydrogel, or by the impregnation
of the alumina support and/or alumina hydrogel at any stage in
its preparation and either after or before calcination of the
alumina hydrogel. One preferred method for adding the platinum
group metal to the alumina support involves the utilization of
a water soluble compound of the platinum group metal to
impregnate the alumina support prior to calcination. E`or
example, platinum may be added to the support by comingling the
uncalcined alumina with an aqueous solution of chloroplatinic
acid. Other water-soluble compounds of platinum may be
employed as impregnation solùtions, including, for example,
ammonium chloroplatinate and platinum chloride. The utilization
of a platinum-chlorine compound, such as chloroplatinic acid,
is preferred since it facilitates the incorporation of both the
platinum and at least a minor quantity of the halogen component
of the catalyst, described hereinafter. It is preferred to
impregnate the support with the platinum group metal when it,
the support, is in a hydrous state. Following this impregnation,
the resulting impregnated support is shaped (e.g., extruded),
dried and subjected to a high temperature calcination or
oxidation procedure at a temperature in the range of about
700F. to about 1500F., preferably of about 850F. to about
1300F., for a period of time of about one hour to about
20 hours, preferably of about one hour to about five hours.
The major portion of the halogen component may be added to this
otherwise fully composited calcined catalyst by contacting
this catalyst with a substantially anhydrous stream of
- halogen-containing gas.
. --11--
'4~5~ 3
An optional and preferred constituent of the catalyst
utilized in the present invention is an additional component
exemplified by rhenium. This component may be present as an
elemental metal, as a chemical compound, such as the oxide,
sulfide, or halide, or in a physical or chemical association
with the alumina support and/or the other components of the
catalyst. Generally, the rhenium is utilized in an amount which
results in a catalyst containing about 0.01% to about 5%, prefer-
ably about 0.05% to about 1.0%, by weight of rhenium, calculated
as the elemental metal. The rhenium component may be incorporated
in the catalyst in any suitable manner and at any stage in the
preparation of the catalyst. The procedure for incorporating
the rhenium component may involve the impregnation of the
alumina support or its precursor either before, during or after
the time the other components referred to above are added.
The impregnation solution can in some cases be an aqueous
solution of a suitable rhenium salt such as ammonium perrhenate,
and the like salts or it may be an aqueous solution of perrhenic
acid. In addition, aqueous solutions of rhenium halides such
as the chloride may be used if desired. It is preferred to use
perrhenic acid as the source of rhenium for the catalysts
utilized in the present invention. In general, the rhenium
component can be impregnated either prior to, simultaneously
with, or after the platinum group metal component is added
to the support. However, it has been found that best results
are achieved when the rhenium component is impregnated simul-
taneously with the platinum group component. In fact, a
; preferred impregnation solution contains chloroplatinic acid
and perrhenic acid. In the instance where the catalyst
support, e.g., alumina derived from hydrous alumina predominating
in alumina mor.ohydrate, is formed into spheres using the
conventional oil drop method, it is preferred to add the
platinum group metal and rhenium after calcination of the
-12-
5~
spheroidal particles. The presently useful catalyst may include
a minor, catalytically effective amount of one or more other
well known promoters, such as germanium, tin, gold, cadmium,
lead, the rare earth metals and mixtures thereof.
Another essential constituent of the ca~alyst used in
the present invention is a halogen component. Although the
precise chemistry o~ the association of the halogen component
with the alumina support is not entirely known, it is customary
in the art to refer to the halogen component as being combined
with the alumina support, or with the other ingredients of the
catalyst. This combined halogen may be fluorine, chlorine,
bromine, and mixtures thereof. Of these, fluorine and,
particularly, chlorine are preferred for the purposes of the
present invention. The halogen may be added to the alumina
~; support in any suitable manner, either during preparation of the
support, or before or after the addition of the catalytically
active metallic component or components. For example, at least
a portion of the halogen may be added at any stage of the pre-
paration of the support, or to the calcined catalyst support,
as an aqueous solution of an acid such as hydrogen fluoride,
hydrogen chloride, hydrogen bromide and the like or as a
substantially anhydxous gaseous stream of these halogen-
containing components. The halogen component, or a portion
thereof, may be composited with alumina during the impregnation
of the latter with the pla~inum group component and/or rhenium
component; for example, through the utilization of a mixture of
chloroplatinic acid and/or perrhenic acid and hydrogen chloride.
In another situation, the alumina hydrogel which is typically
utilized to form the alumina component may contain halogen and
thus, contribute at least a portion of the halogen component to
the final composite. For purposes of the present invention,
-13-
when the catalyst support is used in the form of an extrudate,
it is preferred to add the major portion of the halogen component
to the otherwise fully composited calcined catalyst by contacting
this catalyst with a substantially anhydrous stream of halogen-
containing gas. When the catalyst is prepared by impregnating
calcined, formed alumina, for example, spheres produced by the
conventional oil drop method, it is preferred to impregnate
the support simultaneously with the platinum group metal,
rhenium component and halogen. In any event, the halogen
is preferably added in such a manner as to result in a full~
composited catalyst that contains about 0.1~ to about 5% and
preferably about 0.2% to about 1.5% by weight of halogen calcu-
lated on an elemental basis.
The final fully composited catalyst prepared, for
example, by a method set forth above, is generally dried at a
temperature of about 200F. to about 600F. for a period
of about 2 to a~out 24 hours or more and finally calcined at a
temperature of about 700F. to about 1500F., preferably
about 850F.to about 1300F. for a period of about 1 hour to
about 20 hours and preferably about 1 hour to about 5 hours.
The resultant calcined catalyst may be subjected to
reduction prior to use in reforming hydrocarbons. This step
is designed to insure chemical reduction of at least a portion
of the metallic components.
The reducing media may be contacted with the calcined
catalyst at a temperature of about 800F. to about 1200F. and
at a pressure in the range of about 0 psig. to about 500
psig. and for a period of ti.le of about 0.5 to about 10 hours
or more and, in any event, for a time which is effective to
chemically reduce at least a portion, preferably a major
portion, of each of the metallic components, e.g., platinum
-14-
group metal and rhenium component,of the catalyst. Bychemical reduction is meant the lowering of oxidation states
of the metallic components below the oxidation state of the
metallic components in the unreduced catalyst. For example,
the unreduced catalyst may contain platinum salts in which
the platinum has an oxidation state which can be lowered or
even reduced to elemental platinum by contacting the unreduced
castalyst with hydrogen. This reduction treatment is preferably
performed in situ, (i.e., in the reaction zone in which it is
to be used), as part of a start-up operation using fresh unreduced
catalyst or regenerated (e.g., regenerated by treatment with
an oxygen-containing gas stream) catalyst. The process
of the present invention may be practiced using virgin catalyst
and/or catalyst that has previously been used to reform
hydrocarbon and has been subsequently subjected to conventional
treatments to restore, e.g., regenerate and/or reactlvate, the
hydrocarbon reforming activity and stability of the catalyst.
During step (1), (2), and, in particular, during step
(3) of the present invention, the halogen content of the catalyst
can be maintained at or increased to the desired level, e.g.,
in the range of about 0.1% to about 5% and preferably, in the
range of about 0.2% to about 1.5~ by weight of halogen
calculated on an elemental basis, by the addition of one or
more of any suitable halogen-containing compounds, such as
carbon tetrachloride, ethyl trichloride, t-butyl chloride and
the like, to the reaction zone. For example, during steps (1),
(2) and (3), one or more halogen-containing compounds can be
added to the hydrocarbon and/or hydrogen entering the reaction
zone. Alternately, halogen-containing compounds can be added
to the reaction zone separately from the hydrocarbon feed or
hydrogen.
In the reforming embodiment of the present invention,
the reaction zone pressure utilized is preferably selected in
the range of about 50 psig. to about 1000 psig., with the more
preferred pressure being about 100 psig. to about 600 psig.
Reforming operations may be conducted at the still more preferred
pressure range of about 200 psig. to about ~00 psig. to achieve
substantially increased catalyst life before regeneration.
For optimum reforming results, the temperature in the
reaction zone should preferably be within the range of about
700F. to about 1100F. more preferably in the range of about
800F. to about 1050F. The initial selection of the temperature
within this broad range is made primarily as a function of the
desired octane of the product reformate, considering the
characteristics of the charge stock and of the catalyst. The
temperature may then be slowly increased during the run to
compensate for the inevitable deactivation that occurs, to
provide a constant octane product.
In accordance with the preferred reforming process of
the present invention sufficient hydrogen is supplied to provide
about 2.0 to about 20 moles of hydrogen per mole of hydrocarbon
entering the reaction zone, with excellent results being obtained
when about 7 to about 10 moles of hydrogen are supplied
per mole of hydrocarbon charge stock. Likewise, the overall
weight hourly space velocity, i.e., WHSV, used in reforming
is preferably in the range of about 0.5 to about 10.0 with a
value in the range of about 2.0 to about 5.0 being more preferred.
Individual reaction zones within a series will, of course, operate
at higher WHSV. The preferred ranges of WHSV given above are
based on the total or overall reaction zone system.
.
-16-
The following examples illustrate more clearly the
processes of the present invention. However, these illustrations
are not to be interpreted as specific limitations on this
nventlon .
EXAMPLE I
This example illustrates certain of the benefits of
the present invention.
A commercially available catalyst prepared by co-
impregnating a gamma alumina support with chloroplatinic acid
and perrhenic acid utilizing conventional procedures was
selected for testin~. This catalyst, comprising 0.35% by weight
platinum (calculated on an elemental basis), 0.35~ by weight
rhenium (calculated on an elemental basis) and 1.13% by
weight chlorine (calculated on an elemental basis), was placed
into a fixed bed reaction zone. The catalyst was conventionally
reduced by flowing hydrogen through the reactor. The reduced
cataly~t was used in a "once-through", i.e., no hydrogen
or hydrocarbon recycle, hydrocarbon reforming operation to
reform a naphtha having the following specifications.
API Gravity 54.8
Research Octane
Number ~clear) 47.2
Distillation
(ASTM D-86) IBP 230
10~ 246
30% 255
50% 267
90~ 315
95~ 328
E.P. 370
Component Type
Analysis: Vol.%
Paraffin 45.4
Naphthene 42.6
Aromatic 12.0
Naphtha contained essentially ro su fu-t i.e.,
less than 1 ppm. and less than 20 ppm. by weight of water.
- -17-
`5~
The reforming conditions were as follows:
Temperature**
Weight Hourly Space
Velocity (WHSV) 4.0 };
Pressure 300 psig.
Hydrogen-to-Hydrocarbon
Mole Ratio 7:1 c
**The temperature of the reaction zone `
was varied so as to produce a Cs+ reformate
product having approximately a 95
research octane number (clear).
Chlorobenzene was added to the naphtha feedstock in
an amount sufficient to maintain the concentration of halogen
component on the catalyst at about 1% by weight. This hydrocarbon
reforming test ~as carried out for a period of approximately ~3
1300 hours. During various periods within this time, sulfur
in the form of thiophene and water in the form of isopropanol
(which breaks down to water at conditions existing in the reaction
zone) were added to the naphtha feedstock to determine the
effect of these contaminants on the activity of the catalyst.
Additional amounts of chlorobenzene were added to the feedstock
during periods when water was added to the feedstock. After s
a period of time processing this contaminated feedstock, the
clean feedstock was again fed to the reactor to determine what,
if any, permanent detrimental effect to the catalyst occurred by
processing the contaminated feedstock. The feedstock used
throughout the 1300 hours, both clean feedstock and contaminated
feedstock, contained chlorobenzene to maintain the chlorine ;~
concentration of the catalyst at about 1% by weight. i.
Periodic reformate samples were taken and octane
n~u~ers were obtained on these samples.
Table 1 is a compilation of these data showing the
; time at which a sample ~s taken, the oc an~ number o~ the sa~ple
and the reaction temperature at which the sample was taken.
-18-
.
=These data are as follows:
.~ .
TABLE I
Hrs. on Na~htha _RONC TEMP.F.
4 9804 919.1
26 96.9 919.~
97 95.1 918.6
121 94.5 918.3
139.510 ppm. sulfur added to feed
142 95.2 923.1
' 166 94.0 922.9
190 95.8 929.9
262 94 9 930 3
267Clean feed restored
- 286 94.9 924.8
310 95.0 9~4.4
331.510 ppm. sulfur + 50 ppm. H20
added to feed
334 95.4 929.0
358 95.2 929.6
362.5Clean feed restored
430 94.4 924.8
451.550 ppm. sulfur added to feed
455 94.2 933.6
478 95.6 942.8
J 502 95 3 943 3
506.5Clean feed restored
526 94.2 925.4
599.5 95.0 929.8
62150 ppm. sulfur ~ 500 ppm. H20
added to feed
624 95.5 938.2
647.0 95.0 941.8
671.0 95.1 943.5 --
j 675.5Clean feed restored
- 753.5 94.2 929.9
775100 ppm. sulfur + 1,000 ppm.
H20 added to feed
778 94.~ 944.8
801.5 93.0 948.5
825.5 96.1 964.2
849.5 95.9 965.1
921.5 95.1 964.5
926.5Clean feed restored
945.5 93.5 935.0
969.5 93.7 934.2
9911,000 ppm. sulfur + 1/000 ppm.
H20 added to feed
' 994.5 86.7 967.0
1,018 91.8 999.2
1,021Clean feed restored
7' 1~091 94.g 945.4
1,111.5750 ppm. sulfur + 1,000 pp~.
H20 added to feed
` 1,115 92.0 990.3
1,132 9206 1,004.1
1,155 92.8 1,013.7
1,179 93.7 1,025.4
1,181.5Clean feed restored
1,~51 93.0 953.8
1,276 9S.9 g64.8
1,299 95.9 964.5
-19-
!J
These data indicate quite clearly that sulfur
contamination does repeatedly and substantially deactivate
this catalyst. The reaction temperature increase at a given
reformate octane number is an indication of the activity decline
caused by such contamination. A surprising result shown in these
data is that by maintaining the chloride content of the catalyst
throughout the processing period with both clean and sulfur plus
water contaminated feedstocks, the catalyst activity is restored
to a remarkable degree after the sulfur contamination is removed
from the catalyst. This clearly is an unexpected benefit of
continual halogen addition to maintain or increase catalyst
haloyen concentration.
EXAMPLE II
Example 1 is repeated for a shorter period of time
except that chloride addition was deleted when the contaminated
feedstock was added to the reaction zone. Results of this test
were as set forth below~
Hrs. on Naphtha RONC TEMP F.
.
27 95.6 920.3
98 95.2 919.5 ~
119.5 Cut Cl from feed ---
100 ppm. sulfur + 1,000
ppm. H20 added to feed
122.5 g6.1 934.5
146 95.0 944.3
170 94.2 946.g
194 95.4 954.7
290.5 94.5 960.0
312.5 ~6.0 965.5 `
316.5 Clean feed restored. Cl was not added.
336 93.5 949.6
360.5 94.4 953.7 ~
~32.5 95.0 959.7 ~,
455 95.0 959.5
-20-
These results indicate a striking difference between
the process of the present invention where halogen component is
added to maintain or increase the catalyst halogen concentration
during and after sulfur contamination and where catalyst halogen
concentration is reduced during sulfur contamination. Without
chloride addition, a substantially reduced amount of activity 5,',
is restored to the catalyst even though the sulfur contamination
is removed from the reaction zone. This test clearly demonstrates
the importance of adding halogen component to the reaction zone
to maintain or increase the halogen component concentration on
the catalyst when hydrocarbon materials having undesirably high
sulfur and water concentrations contact the catalyst.
While this invention has been described with respect
to various specific examples and embodiments, it is to be
understood that the invention is not limited thereto and that
it can be variously practiced within the scope of the '~
following claims.
~.
F~
-21- ,
;~
