U.S. patent application number 11/280815 was filed with the patent office on 2006-06-15 for method of converting saturated sulfur compounds of a hydrocarbon cut containing few or no olefins.
Invention is credited to Sebastien LePlat, Nathalie Marchal, Florent Picard.
Application Number | 20060124508 11/280815 |
Document ID | / |
Family ID | 34951725 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124508 |
Kind Code |
A1 |
LePlat; Sebastien ; et
al. |
June 15, 2006 |
Method of converting saturated sulfur compounds of a hydrocarbon
cut containing few or no olefins
Abstract
The invention relates to a method of converting the mercaptans
contained in a hydrocarbon cut containing few or no olefins to
heavier sulfur compounds. The method comprises a first stage of
mixing the cut to be treated with hydrogen and possibly an olefin
cut, then a second stage of reaction of the mixture from the first
stage on a catalyst containing at least one group VIII metal. The
invention also relates to the application of the method to
treatment of a straight-run gasoline.
Inventors: |
LePlat; Sebastien; (Lyon,
FR) ; Picard; Florent; (Saint Symphorien D'Ozon,
FR) ; Marchal; Nathalie; (Saint Genis Laval,
FR) |
Correspondence
Address: |
MILLEN, WHITE, ZELANO & BRANIGAN, P.C.
2200 CLARENDON BLVD.
SUITE 1400
ARLINGTON
VA
22201
US
|
Family ID: |
34951725 |
Appl. No.: |
11/280815 |
Filed: |
November 17, 2005 |
Current U.S.
Class: |
208/217 ;
208/216R |
Current CPC
Class: |
C10G 29/205 20130101;
C10G 45/00 20130101 |
Class at
Publication: |
208/217 ;
208/216.00R |
International
Class: |
C10G 45/04 20060101
C10G045/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 17, 2004 |
FR |
04/12.206 |
Claims
1) A method of converting mercaptans contained in a hydrocarbon
feed containing less than 5% by weight of olefins, comprising at
least two stages: a first stage of mixing the feed to be treated
with an amount of hydrogen, and optionally a stream containing the
resulting mixture having a H.sub.2/olefin molar ratio ranging
between 0.03 and 2, and an olefin/mercaptan molar ratio ranging
between 5 and 5000, and a reaction stage comprising reacting of the
mixture formed at the end of the first stage on a supported
catalyst containing at least one group VIII metal, so as to convert
mercaptans to heavier sulfur compounds with a conversion rate of at
least 50%.
2) A mercaptan conversion method as claimed in claim 1, wherein
said hydrocarbon feed contains less than 1% by weight of
olefins.
3) A mercaptan conversion method as claimed in claim 1, wherein the
reaction stage is carried out at a temperature ranging between
100.degree. C. and 250.degree. C.
4) A mercaptan conversion method as claimed in claim 1, wherein the
reaction stage is carried out at a pressure ranging between 0.5 MPa
and 5 MPa.
5) A mercaptan conversion method as claimed in claim 1, wherein the
reaction stage is carried out at a space velocity ranging between 1
h.sup.-1 and 10 h.sup.-1.
6) A mercaptan conversion method as claimed in claim 1, wherein the
feed to be treated is a straight-run gasoline.
7) A mercaptan conversion method as claimed in claim 1 comprising
adding to the feed to be treated an amount of catalytically cracked
gasoline.
8) A mercaptan conversion method as claimed in further comprising
withdrawing mercaptan-depleted effluent from the reaction stage and
separating said effluent from the sulfur compounds formed during
said reaction stage so as to produce an effluent containing less
than 50% sulfur compounds present in the feed, and a cut containing
the major part of the sulfur compounds.
9) A mercaptan conversion method as claimed in claim 8, wherein
said separating is conducted by flashing or by distillation.
10) A mercaptan conversion method as claimed in claim 1, wherein
the catalyst used in the reaction stage also contains at least one
group VIb metal.
11) A mercaptan conversion method as claimed in claim 1, wherein
the catalyst used in the reaction stage contains between 1% and 30%
by weight of group VIII metal in oxide form, and 0% to 20% by
weight of group VIb metal in oxide form.
12) A mercaptan conversion method as claimed in claim 1, wherein
the catalyst used in the reaction stage contains between 1% and 30%
by weight of NiO, and between 0% to 20% by weight of MoO.sub.3.
13) A mercaptan conversion method as claimed in claim 1, wherein
the catalyst used in the reaction stage is first subjected to a
sulfurization stage so that the proportion of metal present in
sulfide form is above 50%.
14) A method according to claim 1 wherein said resulting mixture
has an H.sub.2 olefin molar ration between 0.05 and 1.
15) A method according to claim 1 wherein said olefin/mercaptan
molar ration is between 10 and 1000.
16) A method according to claim 14 wherein said olefin/mercaptan
molar ration is between 10 and 1000.
17. A method as claimed in claim 1 wherein the reaction s conducted
at a temperature of 140.degree.-240.degree. C. and a pressure of 1
MPa to 3 MPa, and a space velocity of between 1.5 h.sup.-1 and 8
h.sup.-1.
18) A method according to claim 11 wherein the catalyst contains
said group VIb metal in oxide form.
19) A method according to claim 12 wherein the catalyst contains
MoO.sub.3.
20) A method according to claim 13 wherein the proportion of metal
present in sulfide form is above 90%.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method for sweetening and
desulfurizing hydrocarbon fractions generally containing less than
1% by weight of olefins, and sulfur mainly in form of mercaptans.
The method described in the present invention is particularly
suited for treating hydrocarbon fractions resulting from
atmospheric distillation such as, for example, gasoline, kerosine
or light gas oil fractions.
[0002] These hydrocarbon fractions contain variable proportions of
mercaptans which provide them with a corrosive and ill-smelling
acid character. The solutions generally selected for treating these
mercaptans consist in oxidizing the mercaptans to disulfides, then
in separating the latter, which are heavier, generally by
distillation.
[0003] The present invention provides a technical solution for
sweetening the fractions to be treated by converting the mercaptans
to sulfides, and possibly for desulfurizing the fractions to be
treated by separating the sulfides thus formed.
[0004] The method consists in mixing the hydrocarbon fraction to be
treated with, on the one hand, another hydrocarbon fraction
containing unsaturated compounds and, on the other hand, with
hydrogen, then in passing the mixture through a catalyst of metal
sulfide type under optimized conditions so as to promote addition
of the mercaptans on the unsaturated compounds in order to form
sulfur compounds of sulfide type. The sulfur compounds thus
converted have a boiling-point temperature that is higher than
their initial temperature and they can be separated afterwards so
as to recover a sulfur-depleted hydrocarbon fraction.
BACKGROUND OF THE INVENTION
[0005] Reduction of the mercaptan content in hydrocarbon fractions
directly obtained from atmospheric distillation is generally
carried out by means of a method referred to as "sweetening".
[0006] Many sweetening methods do not involve a decrease in the
global sulfur content, but only dimerization of the mercaptans to
disulfides to meet the specifications. This mercaptan oxidation is
generally carried out catalytically with oxygen as the oxidizing
agent.
[0007] On the other hand, extractive sweetening methods allow to
remove the sulfur from the feed. They consist in contacting the
distillate to be treated with a basic aqueous solution (most often
based on sodium hydroxide) which allows the mercaptans to be
recovered. The basic solution is then regenerated by catalytic
oxidation of the sodium mercaptides to disulfides.
[0008] Patent U.S. Pat. No. 3,574,093 describes the implementation
of such a method for lighter gasolines and cuts (C3-C4). Many
improvements have been carried out to the method, such as the use
of aliphatic amines in small amounts in solutions based on sodium
hydroxide (patents U.S. Pat. No. 2,546,345 and U.S. Pat. No.
2,853,431). The method however requires a very large volume of
solution and many extraction stages, which limits its
significance.
[0009] The use of metal hydroxides is not limited to liquid-liquid
extraction. The teaching of patent U.S. Pat. No. 2,808,365 shows
that an "alkaline solid" obtained by action of sodium hydroxide on
calcium carbonate can be used as the catalyst for oxidation of
mercaptans in the presence of epoxides in low proportions in the
feed.
[0010] Other supports such as activated charcoal were impregnated
with a basic solution to act as catalysts (patent GB-763,625).
[0011] Many oxidizing molecules are used in supported form to carry
out oxidation of mercaptans. They however have the drawback of
often leaving unwanted metal traces in the sweetened effluent.
[0012] Patent U.S. Pat. No. 2,255,394 discloses the use of copper
in CuCi.sub.2 form whereas sweetening is performed in the presence
of oxygen by adding organometallic compounds of Et.sub.2Ni type
directly to the feed according to patent U.S. Pat. No.
3,053,756.
[0013] Catalysts based on CrO.sub.3 or, more recently, on cobalt
phthalocyanine are also used. The advantage of the method using
cobalt phthalocyanine is that it can be carried out in supported
phase for simple sweetening or in basic aqueous phase in its
extractive variant.
[0014] The list is not exhaustive and other metals were tested for
oxidizing mercaptans to disulfides.
[0015] Hydrocarbon fraction sweetening can also be carried out by
addition reaction of the mercaptans on the diolefins.
[0016] These reactions are notably considered in the treatment of
gasolines containing both mercaptans and unsaturated hydrocarbon
compounds, such as FCC (Fluid Catalytic Cracking) gasolines for
example, wherein unsaturated compounds, most often of olefinic
nature, are widely present.
[0017] Patent US-2003/0,094,399 A1 describes a method using a
distillation column wherein conversion of the mercaptans to
sulfides is performed at the top of the column through contact with
a hydrogenation catalyst involving a group VIII metal.
[0018] Patent FR-2,821,851 A1 also describes a method for weighting
mercaptans by addition on the olefins by means of a catalyst
comprising at least one group VIII element.
[0019] The same type of reaction is considered in patent U.S. Pat.
No. 5,659,106A on an acid catalyst such as a sulfonated resin. In
this case, the reaction is carried out in the absence of
hydrogen.
[0020] Non-catalytic solutions are also presented in the
literature.
[0021] For example, in patent U.S. Pat. No. 2,694,034, a sweetening
method involving unsaturated compounds is developed. A
mercaptan-rich saturated naphtha is treated by adding an olefinic
compound (1 to 10% by weight) in the presence of a phenylene
diamine type inhibitor, in a proportion of 0.0001% to 1% by weight.
After a sufficient storage time, the mercaptan concentration of the
mixture meets the specifications.
[0022] In conclusion, no solution is provided in the literature for
converting mercaptans in order to sweeten or even to desulfurize
the hydrocarbon fractions resulting from atmospheric distillation,
by catalytic means other than oxidation of the mercaptans to
disulfides.
[0023] Solutions based on the addition of mercaptans to unsaturated
compounds are described only for hydrocarbon fractions containing
large amounts of olefins such as catalytically or thermally cracked
gasolines. The present invention proposes a simple solution for
converting or even separating the saturated sulfur compounds
present in the hydrocarbon fractions resulting from atmospheric
distillation.
SUMMARY OF THE INVENTION
[0024] The method described in the present invention provides a
solution for sweetening or even partly desulfurizing hydrocarbon
fractions free of olefins or containing low unsaturated compound
proportions. What is referred to as hydrocarbon fractions
containing few or no olefins are fractions with less than 5%
olefins, preferably less than 1% olefins.
[0025] The method described in the present invention is
particularly suited for treatment of hydrocarbon fractions
resulting from atmospheric distillation such as, for example,
gasoline, kerosine or light gas oil fractions.
[0026] The method consists in mixing with the hydrocarbon fraction
to be treated hydrogen and possibly another hydrocarbon fraction
containing olefins, referred to as olefinic fraction. This olefinic
fraction generally results from cracking methods such as FCC, steam
cracking or a coking plant. The hydrogen can come from any source
present in the refinery. The necessary hydrogen amounts are
generally small enough not to require an additional dedicated
hydrogen production plant. The resulting mixture must be such that,
on the one hand, the H2/olefin molar ratio ranges between 0.03 and
2, preferably between 0.05 and 1, more preferably between 0.2 and
0.8, and that, on the other hand, the olefin/mercaptan molar ratio
ranges between 5 and 5000, preferably between 10 and 1000, more
preferably between 80 and 600, or even between 150 and 400.
[0027] The mixture meeting the aforementioned two conditions is
then injected into a reactor containing a catalyst likely to react
saturated sulfur compounds such as the mercaptans present. To be
effective, the reaction has to be carried out in the presence of
hydrogen.
[0028] According to a preferred embodiment of the invention, the
non-olefinic feed treated is a gasoline fraction resulting from
atmospheric distillation whose end boiling point is below
250.degree. C., preferably below 220.degree. C. But, in some cases
still belonging to the field of the invention, the feed to be
treated can itself contain a certain amount of olefins to which
only a determined amount of hydrogen has to be added to reach the
afore-mentioned H2/olefin ratio range between 0.03 and 2,
preferably between 0.05 and 1.
[0029] In cases where a certain amount of olefins also has to be
added to the feed to be treated, these olefins generally come from
an olefinic gasoline such as, for example, a cracked gasoline from
a catalytic or thermal cracking plant.
[0030] The method of converting the mercaptans contained in a
hydrocarbon feed containing less than 1% olefins according to the
invention can comprise an additional stage of separation of the
sulfur compounds formed during the reaction stage, so as to produce
an effluent containing less than 50% by weight of the sulfur
compounds present in the feed, and a cut containing the major part
of the sulfur compounds.
[0031] The method according to the invention thus allows mercaptans
to be converted to heavier sulfur compounds with a conversion rate
of generally at least 50% by weight.
DETAILED DESCRIPTION
[0032] The invention can be defined as a method for treating a
hydrocarbon feed, generally a gasoline containing few or no
olefins, generally less than 5% olefins, typically less than 1%
olefins, so as to convert and possibly to eliminate the sulfur
compounds it contains, notably the mercaptans. The method according
to the invention comprises at least 2 stages:
[0033] a first stage referred to as mixing stage, which consists in
mixing the mercaptan-containing hydrocarbon feed to be treated with
a certain amount of hydrogen and possibly with an olefinic
fraction,
[0034] a second stage referred to as reaction stage, which consists
in reacting the mixture resulting from the first stage on a
catalyst comprising at least one group VIII metal so as to convert
the mercaptans to sulfides. This reaction is referred to hereafter
as conversion of mercaptans to sulfides.
[0035] The hydrocarbon feed to be treated generally contains less
than 1% by weight of olefins and more than 50 ppm by weight of
sulfur, mainly in form of mercaptans.
[0036] The present invention applies more particularly to the
treatment of gasoline cuts directly resulting from atmospheric
distillation, which are generally practically free of olefins and
rich in saturated sulfur compounds. It can however be applied to
other feeds such as distillates also containing few or no
olefins.
[0037] What is referred to as saturated sulfur compounds are the
sulfur compounds belonging to the mercaptan or sulfide family.
[0038] The boiling temperatures of the feed to be treated are below
350.degree. C., preferably below 250.degree. C., which generally
corresponds to a gasoline cut.
[0039] The olefinic fractions present in the refinery generally
come from cracking plants such as catalytic, thermal or steam
cracking plants. The boiling temperatures of this olefinic fraction
are generally below 250.degree. C.
[0040] However, hydrocarbon fractions containing olefins with 4, 5
or 6 carbon atoms are preferably used in order to improve the yield
of the sulfur compound weighting reaction.
[0041] The hydrogen also comes in most cases from the refinery. A
hydrogen practically free of H.sub.2S is used because this
component can react with the olefins and form unwanted sulfur
compounds. The hydrogen can come from either a specific hydrogen
production plant or from the gasoline catalytic reforming plant for
example.
[0042] The reaction stage consists in passing the mixture obtained
at the end of the mixing stage through a fixed-bed catalyst under
optimized operating conditions.
[0043] The catalyst used in the reactor is a catalyst comprising at
least one group VIII metal deposited on an inert support based on a
porous metal oxide. Preferably, the support consists of alumina,
silica, titanium oxide, or it contains at least 50% alumina.
[0044] A group VIb metal can also be associated with the group VIII
metal to form a bimetallic catalyst.
[0045] The proportion of group VIII metal in oxide form ranges
between 1% and 30% by weight. The proportion of group VIb metal in
oxide form ranges between 0% and 20% by weight.
[0046] Nickel-based catalysts or catalysts based on mixed nickel
and molybdenum or tungsten oxide are preferably used.
[0047] Typically, the catalyst used in the reaction stage contains
between 1% and 30% by weight of NiO and between 0% and 20% by
weight of MoO.sub.3.
[0048] Prior to injecting the feeds to be treated, the catalyst can
first be subjected to a sulfurization stage in order to convert the
metal oxides to sulfides.
[0049] Sulfurization is carried out in the presence of H.sub.2S,
either injected directly in admixture with hydrogen, or generated
in situ in the reactor by hydrogenolysis of a sulfur compound, so
that the sulfurization rate of the catalyst metals is above 50%,
preferably above 90%.
[0050] The temperature of the reactor generally ranges between
100.degree. C. and 250.degree. C., preferably between 140.degree.
C. and 200.degree. C.
[0051] The reactor is operated at a pressure ranging between 0.5
MPa and 5 MPa, preferably between 1 MPa and 3 MPa, and at a space
velocity ranging between 1 h.sup.-1 and 10 h.sup.-1, preferably 1.5
h.sup.-1 and 8 h.sup.-1.
[0052] The hydrogen flow rate is generally adjusted in order to
obtain a hydrogen/olefin molar ratio ranging between 0.03 and 2,
preferably between 0.05 and 1.
[0053] Under such conditions, surprisingly, the saturated sulfur
compounds present in the feed are converted to saturated sulfur
compounds of higher boiling point temperature.
[0054] The saturated compounds belong to the families consisting of
mercaptans, sulfides and CS.sub.2.
[0055] The conversion is measured by the conversion rate of the
mercaptans to heavier compounds, i.e. having a higher boiling point
temperature.
[0056] Furthermore, the olefin/hydrogen molar ratio is optimized in
order to limit deactivation of the catalyst by the carbon deposit
due to the olefinic compounds.
[0057] In the absence of hydrogen, the catalyst undergoes a high
deactivation and the mercaptan conversion rate is markedly
decreased.
[0058] At the end of the reaction stage, the effluent is depleted
in light saturated sulfur compounds and more particularly in
mercaptans.
[0059] The conversion rate of mercaptans containing 1 to 4 carbon
atoms generally ranges between 50% and 100%. The fraction thus
produced is therefore sweetened in the sense known to the man
skilled in the art.
[0060] A third stage can optionally be carried out if it is desired
to lower the sulfur content of the feed to be treated.
[0061] This third stage, referred to as separation stage, consists
in separating the sulfur compounds formed during the reaction stage
from the hydrocarbon effluent of said reaction stage.
[0062] The separation stage can consist of any method capable of
achieving this separation.
[0063] However, a physical separation method based on the boiling
point temperatures of the compounds to be separated such as, for
example, a simple flash or distillation in a distillation column is
preferably used.
[0064] In this case, the light fraction recovered at the top of the
column contains the major part of the saturated hydrocarbon
fraction and it is depleted in sulfur compounds and in
mercaptans.
[0065] The heavy fraction collected at the bottom of the column
concentrates the sulfur compounds formed during the reaction stage.
This fraction can be treated in a hydrodesulfurization plant to
extract the sulfur therefrom. Implementation of the separation
stage after the reaction stage thus allows to desulfurize the
hydrocarbon feed to be treated without requiring a conventional
hydrodesulfurization method for at least part of the hydrocarbon
effluent.
EXAMPLES
[0066] A series of tests was performed in a pilot plant with 100
cm.sup.3 catalyst.
[0067] The catalyst used contains nickel and molybdenum on an
alumina support (catalyst marketed under reference HR845 by the
Axens Company). Prior to injecting the feed, the catalyst is
sulfurized by a H.sub.2+H.sub.2S mixture at 350.degree. C. During
the tests, the temperature, the pressure and the space velocity are
maintained constant respectively at 180.degree. C., 2.5 MPa and 4
h.sup.-1 for all the tests carried out.
Example 1
According to the Prior Art
[0068] In this example, a gasoline A resulting from atmospheric
distillation of a crude oil is injected into a reactor in the
absence of hydrogen.
[0069] At the reactor outlet, effluent B 1 is separated by
distillation into two fractions with a cut point corresponding to a
temperature of 100.degree. C. The two fractions obtained are
denoted by LCN1 (light fraction) and HCN1 (heavy fraction). The
characteristics of the various gasolines are given in Table 1.
TABLE-US-00001 TABLE 1 Characteristics Gasoline A Effluent B1 LCN1
HCN1 T.sub.5%-T.sub.95% 25-125 25-125 25-100 100-125 Yield per
fraction (%) 100 100 74.6 25.4 15/4 density 0.702 0.705 0.68 0.763
Total sulfur (ppm) 300 300 135 783 Mercaptan sulfur 160 129 135 111
(ppm) Olefin/RSH (mol/mol) 2.4 -- -- -- H.sub.2/Olefin (mol/mol) 0
-- -- -- Gas chromatography (% wt) Paraffins 67.4 67.4 74.6 47.4
Olefins 0.1 0.1 0.1 0.0 Naphthenes 26.2 26.2 23.4 34.0 Aromatics
6.3 6.3 1.9 18.6
[0070] The presence of the catalyst allows the mercaptan content to
be reduced by 20%.
[0071] However, the mercaptan content of cut LCN1 remains high, and
the mercaptan distribution between cuts LCN1 and HCN1 shows that
the conversion observed equally affects the light mercaptans and
the heavy mercaptans with at least five carbon atoms. Furthermore,
the organic sulfur content remains unchanged during treatment on
the catalyst.
[0072] The absence of hydrogen and a very low unsaturated compound
content in the feed do not allow to obtain a notably desulfurized
light cut. However, the sulfur of this fraction is present
exclusively in mercaptan form, so that the non-mercaptan sulfur is
consequently concentrated in the heavy fraction.
Example 2
According to the Invention
[0073] Gasoline A is mixed with an olefinic cracked gasoline C from
a catalytic cracking plant prior to being injected into the reactor
in the presence of hydrogen in a proportion of 5 litres hydrogen
per litre feed. Gasoline C represents 10% by weight of the mixture
referred to as gasoline D1. Gasoline D1 mixed with the hydrogen is
injected on the catalyst.
[0074] At the reactor outlet, effluent B2 is separated by
distillation into two fractions with a cut point corresponding to a
temperature of 100.degree. C. The two fractions obtained are
denoted by LCN2 (light fraction) and HCN2 (heavy fraction). Table 2
shows the characteristics of gasolines A, C and D1. The
characteristics of the various cuts are given in Table 3.
TABLE-US-00002 TABLE 2 Characteristics Gasoline A Gasoline C
Gasoline D1 T.sub.5%-T.sub.95% 25-125 25-215 25-215 15/4 density
0.702 0.746 0.707 Total sulfur (ppm) 300 177 279 Mercaptan sulfur
(ppm) 160 8 151 Olefin/RSH (mol/mol) 2.4 16,430 91 Gas
chromatography (% wt) Paraffins 67.4 28.9 63.5 Olefins 0.1 34.5 3.6
Naphthenes 26.2 7.6 24.4 Aromatics 6.3 29 8.5
[0075] TABLE-US-00003 TABLE 3 Characteristics Gasoline D1 Effluent
B2 LCN2 HCN2 T.sub.5%-T.sub.95% 25-215 25-215 25-100 100-215
Fraction/Gasoline D1 100 100 71.5 28.5 (% wt) 15/4 density 0.707
0.708 0.683 0.779 Total sulfur (ppm) 279 279 34 893 Mercaptan
sulfur 151 64.5 34 141 (ppm) Olefin/RSH (mol/mol) 91 -- -- --
H.sub.2/Olefin (mol/mol) 0.71 -- -- -- Gas chromatography (% wt)
Paraffins 63.5 63.6 72.3 43 Olefins 3.6 3.5 3.2 4.1 Naphthenes 24.4
24.4 22.7 28.4 Aromatics 8.5 8.5 1.9 24.6
[0076] The simultaneous presence of olefins and of hydrogen in
mixture D1 allows the initial mercaptan content to be reduced by
57%. The conversion is three times the conversion observed in
example 1. Furthermore, the mercaptan distribution between cuts LCN
2 and HCN2 is widely modified, the light mercaptans contained in
cut LCN2 are preferentially converted.
Example 3
According to the Invention
[0077] Gasoline A is mixed with cracked gasoline C prior to being
injected into the reactor in the presence of hydrogen in a
proportion of 5 litres hydrogen per litre feed. Gasoline C
represents 20% by weight of the mixture denoted by gasoline D2.
[0078] At the reactor outlet, effluent B3 is separated by
distillation into two fractions with a cut point corresponding to a
temperature of 100.degree. C. The two fractions obtained are
denoted by LCN3 (light fraction) and HCN3 (heavy fraction). Table 4
shows the characteristics of gasolines A, C and D2. The
characteristics of the various cuts are given in Table 5.
TABLE-US-00004 TABLE 4 Characteristics Gasoline A Gasoline C
Gasoline D2 T.sub.5%-T.sub.95% 25-125 25-215 25-215 15/4 density
0.702 0.746 0.715 Total sulfur (ppm) 300 177 270 Mercaptan sulfur
160 8 134 (ppm) Olefin/RSH (mol/mol) 2.4 16,430 196 Gas
chromatography (% wt) Paraffins 67.4 28.9 59.8 Olefins 0.1 34.5 6.9
Naphthenes 26.2 7.6 22.5 Aromatics 6.3 29 10.8
[0079] TABLE-US-00005 TABLE 5 Characteristics Gasoline D2 Effluent
B3 LCN3 HCN3 T.sub.5%-T.sub.95% 25-215 25-215 25-100 100-215
Fraction/Gasoline D2 100 100 68.5 31.5 (% wt) 15/4 density 0.715
0.717 0.685 0.788 Total sulfur (ppm) 270 270 32 789 Mercatan sulfur
(ppm) 134 71 32 156 Olefin/RSH (mol/mol) 196 -- -- --
H.sub.2/Olefin (mol/mol) 0.37 -- -- -- Gas chromatography (% wt)
Paraffins 59.8 59.9 69.7 39.4 Olefins 6.9 6.8 6.6 7.2 Naphthenes
22.5 22.5 21.9 23.8 Aromatics 10.8 10.8 1.8 29.6
[0080] The increase in the amount of olefins injected does not
significantly improve the performances, the mercaptan conversion
stagnates around 50%. The H.sub.2/olefin ratio is decreased, which
favours catalyst deactivation problems.
Example 4
According to the Invention
[0081] Gasoline A is mixed with cracked gasoline C prior to being
injected into the reactor in the presence of hydrogen in a
proportion of 10 litres hydrogen per litre feed.
[0082] Gasoline C represents 10% of the mixture that is denoted by
gasoline D3.
[0083] At the reactor outlet, effluent B4 is separated by
distillation into two fractions with a cut point corresponding to a
temperature of 100.degree. C. The two fractions obtained are
denoted by LCN4 (light fraction) and HCN4 (heavy fraction). Table 6
gives the characteristics of the various gasolines. TABLE-US-00006
TABLE 6 Characteristics Gasoline D3 Effluent B4 LCN4 HCN4
T.sub.5%-T.sub.95% 25-215 25-215 25-100 100-215 Fraction/Gasoline
100 100 71.6 28.4 D1 (% wt) 15/4 density 0.707 0.704 0.682 0.78
Total sulfur (ppm) 279 279 32 901 Mercaptan sulfur 151 63 32 141
(ppm) Olefin/RSH 91 -- -- -- (mol/mol) H.sub.2/Olefin (mol/mol)
1.43 -- -- -- Gas chromatography (% wt) Paraffins 63.5 63.8 72.4
43.4 Olefins 3.6 3.2 3 3.8 Naphthenes 24.4 24.4 22.7 28.4 Aromatics
8.5 8.5 1.9 24.6
[0084] The presence of unsaturates and the presence of hydrogen are
two factors favouring mercaptan conversion. However, the
H.sub.2/olefin ratio also has to be optimized to limit catalyst
deactivation, hydrogen consumption and olefin saturation.
[0085] Without further elaboration, it is believed that one skilled
in the art can, using the preceding description, utilize the
present invention to its fullest extent. The preceding preferred
specific embodiments are, therefore, to be construed as merely
illustrative, and not limitative of the remainder of the disclosure
in any way whatsoever.
[0086] In the foregoing and in the examples, all temperatures are
set forth uncorrected in degrees Celsius and, all parts and
percentages are by weight, unless otherwise indicated.
[0087] The entire disclosures of all applications, patents and
publications, cited herein and of corresponding French application
No. 04/12.206, filed Nov. 17, 2004 are incorporated by reference
herein.
[0088] The preceding examples can be repeated with similar success
by substituting the generically or specifically described reactants
and/or operating conditions of this invention for those used in the
preceding examples.
[0089] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention
and, without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *