WO2006120378A1 - Procede d'hydrodesulfuration selective de naphta - Google Patents

Procede d'hydrodesulfuration selective de naphta Download PDF

Info

Publication number
WO2006120378A1
WO2006120378A1 PCT/GB2006/001567 GB2006001567W WO2006120378A1 WO 2006120378 A1 WO2006120378 A1 WO 2006120378A1 GB 2006001567 W GB2006001567 W GB 2006001567W WO 2006120378 A1 WO2006120378 A1 WO 2006120378A1
Authority
WO
WIPO (PCT)
Prior art keywords
stage
hydrogen
reactive compound
naphtha
process according
Prior art date
Application number
PCT/GB2006/001567
Other languages
English (en)
Inventor
Rafael Menegassi De Almeida
Jefferson Roberto Gomes
Marcelo Edral Pacheco
Marcus Vinicius Eiffle Duarte
Rogério ODDONE
Giane Ribeiro Stuart
Original Assignee
Petróleo Brasileiro S A - Petrobras
Benson, John, Everett
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Petróleo Brasileiro S A - Petrobras, Benson, John, Everett filed Critical Petróleo Brasileiro S A - Petrobras
Priority to ES06726947.2T priority Critical patent/ES2586567T3/es
Priority to MX2007015794A priority patent/MX2007015794A/es
Priority to DK06726947.2T priority patent/DK1891183T3/en
Priority to EP06726947.2A priority patent/EP1891183B1/fr
Publication of WO2006120378A1 publication Critical patent/WO2006120378A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
    • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
    • C10G65/04—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including only refining steps
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
    • C10G2400/02—Gasoline

Definitions

  • the present invention relates to a process for the selective hydrodesulfurization of a naphtha flow containing organosulfur compounds and olefins. More particularly, the process comprises two reaction stages wherein the naphtha charge contacts a flow of hydrogen and at least one added non- reactive compound and H 2 S is removed from the effluent of the first reaction stage.
  • FCC naphthas fluidized catalytic cracking naphthas
  • FCC naphthas typically have a sulfur content ranging from 1 ,000 to 1 ,500 mg/kg.
  • FCC naphthas typically have an olefin content from 25-35% by mass.
  • HDS hydrodesulfurization
  • an olefinic naphtha can initially be separated into two distillation fractions so that only the heavy fraction can be subjected to a hydrodesulfurization reaction. Following the reaction, both fractions are restored, and the olefins in the light olefinic fraction can be preserved.
  • This method provides gasoline with a reduced sulfur content while preserving its octane rating.
  • U.S. Patent Nos. 2,070,295, 3,957,625 and 4,397,739 disclose this type of processing, though with some sulfur remaining in the light naphtha.
  • U.S. patent application 2003/0042175 discloses a process with an additional stage for alkylating thiophenic sulfur in the light naphtha in order to concentrate the sulfur in the heavy naphtha.
  • U.S. Patent Nos. 3,957,625, 4,334,982, and 6,126,814 disclose catalytic formulations whose catalyzing characteristics selectively favor hydrodesulfurization while reducing olefin hydrogenation.
  • HDS processes involving olefinic naphthas use catalysts based on transition metal-oxides from Group Vl B, preferably MoO 3 , and transition metal oxides from Group VIII, preferably CoO, in the form of sulfides, supported on an appropriate porous solid.
  • Supports preferably have their acidity reduced by using additives, or else their composition is of intrinsic low acidity. Variations in the metal content are also known, with optimum relationships among them.
  • U.S. Patent No. 2,793,170 discloses that low pressures favor a lesser degree of olefin hydrogenation without hindering hydrodesulfurization.
  • the foregoing patent also discloses that, in addition to reactions whereby organosulfur compounds are converted, there is also a reaction recombining the H 2 S produced by the reactions with the remaining olefins, forming mercaptan compounds. Such reaction makes it difficult to obtain sufficiently low sulfur content in the product without triggering extensive hydrogenation of the olefins. High temperatures also hinder the reaction whereby olefins are recombined with H 2 S.
  • the inventor's patent application BR-0202413-6 discloses using a mixture of at least one added non-reactive compound with hydrogen to trigger selective hydrodesulfurization of a charge of cracked olefin flows.
  • the mixture increases dilution of the hydrogen in the reaction and minimizes olefin hydrogenation without significantly decreasing the conversion of organosulfur compounds.
  • the mixture decreases the concentration of H 2 S generated in the reaction and minimizes recombination. It can be seen that a higher ratio of gas per charge volume indicates a decrease in the sulfur content of the product.
  • the desired effect of the increased selectivity is achieved not only with nitrogen but also with various diluting compounds and mixtures thereof. It can further be seen that a drop in total pressure does not lead to the same reaction selectivity obtained by using at least one added non-reactive compound. It reduces olefin conversion but increases the sulfur content of the product.
  • Patent application WO 03/085068 discloses a selected hydrodesulfurization process wherein a mixed charge of naphtha flows with an olefin content of greater than 5% m/m reacts under normal hydrodesulfurization conditions while contacting a selective catalyst.
  • the process is intended to reduce the sulfur content by more than 90% and to hydrogenate less than 60% of the olefins in the charge.
  • Octane rating loss is expected to be greater from separately treated flows than from naphthas treated as a mixture.
  • Co- processing of a mixture of an olefinic naphtha flow with a non-olefinic naphtha in an amount ranging from 10% to 80% by mass results in at least a 0.1 increase in the octane rating of the final product in comparison to the product processed separately in two charges.
  • a non-olefinic naphtha no other component is considered for the oiefinic naphtha mixture.
  • the non-olefinic naphtha will form part of the final gasoline formulation, thereby limiting the application of co-processing.
  • U.S. Patent Nos. 6,429,170 and 6,482,314 disclose a process for removing sulfur from catalytic cracking naphtha in a single reaction stage.
  • the process uses a partially sulfided Ni- or Co-based regeneratable reactive adsorbent on a ZnO support.
  • the zinc oxide absorbs the H 2 S resulting from conversion of the organosuifurized compounds, preventing the recombination reaction, thereby resulting in process selectivity.
  • U.S. Patent Application 2003/0232723 uses nitrogen in the adsorption process with a regeneratable reactive adsorbent to boost selectivity, wherein the hydrogen molar fraction in the mixture (H 2 + N 2 ) must be greater than 0.8.
  • hydrodesulfurization processes have been applied to more than one reaction stage, in which the H 2 S generated in the reaction is removed between the stages.
  • U.S. Patent No. 2,061 ,845 discloses the use of more than one reaction stage with H 2 S removed between the stages in the hydrotreatment of cracked gasolines, leading to lesser hydrogenation of olefins and a lower octane rating decrease in comparison to single-stage hydrotreatment.
  • U.S. Patent No. 3,732,155 discloses the use of two stages with H2S removed between them, and without the charge contacting hydrogen in the second reaction stage.
  • U.S. Patent No. 3,349,027 discloses hydrotreatment of olefinic naphthas in two stages, with an intermediate removal of H2S and with a high space velocity (LHSV), making it possible to remove virtually all the mercaptans.
  • LHSV high space velocity
  • U.S. Patent No. 5,906,730 discloses a hydrodesulfurization process for a cracked naphtha in two or more reaction stages, with 60-90% of the sulfur in the charge of each stage removed, allowing for total removal of up to 99% of the sulfur in the original naphtha and with less conversion of olefins in comparison to just one reaction stage.
  • U.S. Patent No. 6,231 ,753 discloses a hydrodesulfurization process with two reaction stages, with more than 70% of the sulfur removed in the first stage and 80% of the remaining sulfur removed in the second stage, leading to a total removal of more than 95% of the charge sulfur. Between two reaction stages H 2 S is removed.
  • this patent claims a second stage where the temperature and LHSV are higher than those in the first stage: temperature 10 0 C higher and LHSV at least 1.5 times higher.
  • inert compounds that may constitute part of the make-up hydrogen result from hydrogen preparation processes.
  • the presence and concentration of so-called inert compounds depend on the presence or not as well as on the efficiency of the H 2 purification units.
  • Hydrogen is typically produced in units such as steam reform or as by-product from naphtha catalytic reform.
  • the hydrogen stream from the catalytic reform contains methane and light hydrocarbons, while that from steam reform of natural gas can contain N 2 .
  • Natural gas used as reform feed can also contain N 2 in amounts lower than 10% by volume.
  • Cryogenic processes, membrane separation and molecular sieve adsorption - PSA (Pressure Swing Adsorption) are the most widely used techniques for the purification of such streams.
  • inert compounds are considered as undesirable contaminants, so that usually high-purity make-up hydrogen is employed so as to avoid collection of such inert compounds in the gas recycle of hydrorefining units.
  • make-up hydrogen is preferably a high- purity stream.
  • the amount of such compounds in the reaction medium will depend on (i) the recycle flow rate in the system, (ii) the hydrogen consumption, (iii) the make-up flow rate, (iv) the equilibrium in the separator vessels and (v) the presence or not of further treatment of the recycle gas for H 2 S withdrawal, which can also remove some of the inert compounds.
  • U.S. patent application 2003/0217951 discloses two reaction stages with H 2 S removed between them. This process differs from those in the previously cited patents in that more than 90% of the sulfur is converted in the first stage and the reaction rate in the second stage is slower than that in the first stage. A slower reaction rate can be obtained at a temperature lower than that in the first stage.
  • U.S. Patent No. 6,736,962 discloses a two-stage process for removing sulfur, with an intermediate H 2 S removal step between them.
  • the purge gas is hydrogen
  • the second-stage catalyst is an irreducible oxide (merely a support, with no hydrogenating activity).
  • the second-stage catalyst is an oxide of a metal from Group VIIIB enhanced by an oxide of a metal from the supported Group VIB (hydrorefining catalyst).
  • the invention does not contemplate mixtures of a purge gas and hydrogen.
  • Typical conditions for each reaction stage in HDS processes are: pressures ranging from 0.5 to 4.0 MPaG, preferably from 2.0 to 3.0 MPaG; temperatures ranging from 200 to 400 0 C, preferably from 260 to 340 0 C; space velocity (volume processed per hour per volume of catalyst), or SV, from 1 to 10 h "1 ; rate of hydrogen volume per processed charge volume ranging from 35 to 720 Nm 3 /m 3 ; and hydrogen purity normally higher than 80%, and preferably higher than 90%.
  • the H2S concentration at the second stage intake should preferably be less than 0.05% by volume (500 ppmv), or more preferably, the H 2 S concentration in the gas produced by the second reactor should be less than 0.05% by volume so that it may be recycled back to the first reactor untreated.
  • the present invention relates to a process for the selective hydrodesulfurization of a naphtha flow containing organosulfurized compounds and olefins, which reduces the sulfur content while minimizing hydrogenation of the olefins found in the charge.
  • the process comprises a two-stage catalytic hydrodesulfurization reaction whereby the naphtha charge contacts a flow of hydrogen and at least one added non-reactive compound, with H 2 S removed from the effluent from the first reaction stage.
  • a charge of naphtha contacts a flow of hydrogen and at least one added non-reactive compound wherein the H 2 molar fraction ranges from 0.2 to 1 , and with the H 2 S concentration at the reactor intake limited to not more than 0.1% by volume.
  • Effluent from the first stage of the reaction is then subjected to a step for removing the H 2 S.
  • the partially hydrodesulfurized naphtha is piped to a second reaction stage in a reactor charged with a second hydrorefining catalyst, under second hydrodesulfurization conditions, where it contacts a flow of hydrogen and at least one added non-reactive compound wherein the H 2 molar fraction ranges from 0.2 to 0.7, and with the H 2 S concentration at the reactor intake limited to not more than 0.05% by volume in order to recover a hydrodesulfurized naphtha, the selectivity of which is improved as compared to state-of-the-art processes.
  • the hydrodesulfurization process of the present invention preserves the olefins while producing hydrodesulfurized olefinic naphthas, advantageously by using at least one added non-reactive compound mixed with hydrogen and under optimized hydrodesulfurization reaction conditions during both stages or alternatively during the second stage only.
  • BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates the effects of nitrogen on the hydrodesulfurization and hydrogenation of olefins in a naphtha charge, for both the first and second stages of the reaction, in accordance with EXAMPLES 1 to 4, wherein H 2 S was removed between the two stages.
  • Fig. 2 illustrates the state of art of a single-stage process for a hydrodesulfurization reaction involving a naphtha charge, in accordance with EXAMPLE 5, with and without nitrogen mixed with hydrogen.
  • the present invention relates to a catalytic hydrodesulfurization process in two reaction stages involving a charge of a naphtha containing olefins and organosulfurized compounds with a flow comprising a mixture of hydrogen and at least one added non-reactive compound.
  • H 2 S is removed from the effluent in the first reaction-stage and a hydrodesulfurized olefinic naphtha is recovered wherein the sulfur content has typically been reduced by more than 90% by mass and the olefins in the charge have typically been hydrogenated to a maximum of 40% by mass.
  • Olefinic naphthas containing organosulf ur compounds that can be applied to the process of the present invention include, but are not limited to catalytic cracking naphthas; fractionated catalytic cracking naphthas, the light or heavily fractions thereof and narrow fractions; naphthas and their fractions, previously hydrogenated to remove dienes; and naphthas from delayed coking, etc.
  • Typical charges for the process of the present invention include olefinic naphthas having an olefin concentration ranging from 20% to 50% by mass and a sulfur concentration ranging from 300 to 7,000 mg/kg.
  • the naphtha charge contains an olefin concentration ranging from 25% to 35% by mass and a sulfur concentration from 1,000 to 1,500 mg/kg.
  • Naphthas obtained from catalytic cracking units frequently contain such an olefin concentration and sulfur concentration.
  • Olefinic naphthas may also contain dienes, which is undesirable for a process if dienes are present at a high concentration (exceeding 1.0 g l 2 /100 g).
  • the charge should be pretreated by selective hydrogenation under conditions of low severity in order to hydrogenate only the dienes and thus prevent coke from forming in heat exchangers and furnaces upstream from the first-stage reactor of the hydrodesulfurization reaction, or at the top of the reactor.
  • the present invention comprises a two-stage reaction, conducted under usual hydrodesulfurization conditions and at the usual volumetric rates, or lower rates, for hydrogen with regard to the charge. At least one added non-reactive compound is mixed witf ⁇ the hydrogen to constitute a flow admitted into the reactor preferably at a temperature higher than the dew point of the mixture.
  • Added non-reactive compounds useful for the process of the present invention are selected from the group consisting of nitrogen, noble gases, saturated hydrocarbons (from C1 to C4), and mixtures thereof.
  • the added non-reactive compounds should be made up of at least 90% by volume of non-reactive compounds under the hydrodesulfurization process conditions. Further, the sulfur content of such non-reactive compounds is lower than 500 ppm and their olefin content is lower than 10% by weight.
  • hydrodesulfurization catalyst contains metals Ni or Co and Mo or W.
  • hydrorefining catalysts are preferably those comprising oxides of the Group VIB and/or VIII metals supported on an appropriate porous solid. Sulfided catalysts comprising a mixture of oxides of a Group VIII metal of Ni or Co, and a Group VIB metal of Mo or W, prior to sulfiding, may be employed in the invention.
  • Catalysts containing CoO and MoO 3 offer a better desulfurizing capacity than those containing NiO and MoO 3 , resulting in less olefinic hydronation for the same degree of hydrodesulfurization.
  • the oxides are supported on a porous solid.
  • a porous solid are alumina, silica, zeolites, titanium, carbon, aluminum phosphate, zinc oxide, and diatomaceous earth.
  • the oxides are preferably supported on alumina or supports of low acidity.
  • the intrinsic acidity of a catalyst support can be reduced, either by using mixed oxides such as AI 2 O 3 and MgO as a support, or by depositing Group I alkaline-earth metal compounds and/or Group Il alkaline-earth metals.
  • mixed oxides such as AI 2 O 3 and MgO
  • MgO mixed oxide
  • pure or mixed with AI 2 O 3 basic oxides such as CaO, BeO, BaO, SrO, La 2 O 3 , CeO 2 , Pr 2 O 3 , Nd 2 O 3 , SmO 2 , K 2 O, Cs 2 O, Rb 2 O, OrZrO 2 , pure or mixed with alumina, can be used.
  • the use of a mixture of various hydrorefining catalysts can also be considered in the hydrodesulfurization reactors, as well as catalysts deactivated by having been previously used in another hydrorefining unit.
  • the content of Group VIB and of the Group VIII metals as oxides on the catalytic support is generally in the range of 5 to 30% by mass.
  • Each reaction stage can comprise one or more hydrorefining reactor, and each reactor can comprise one or more reaction sections. Each reaction section can comprises a different catalyst. Hydrogen alone or hydrogen admixed to the at least one added non-reactive compound or the at least one non-reactive compound alone is added between stages. Besides the addition of a gas stream, a portion of the charge or of the products can be added between reaction stages. Such addition of streams between reaction stages aims at reducing reaction temperature before the mixture attains the next reactor section. It is well known that the hydrogenation reaction is exothermic. If the product temperature is not carefully controlled, olefin hydrogenation can be extensive and hot spots are formed in the reactor.
  • the presence of added non-reactive compounds inhibits olefin hydrogenation and accommodates the reaction heat, so that temperature increase is limited.
  • the injection of a stream designed to take heat between reactor sections is dispensed with.
  • each reactor section can contain a different hydrorefining catalyst, among those described hereinbefore.
  • each reaction stage can contain the same catalyst as the other stage.
  • the reaction stages each contain a different catalyst.
  • the preferred catalyst includes usual hydrorefining catalysts, such as a sulfided, alumina-supported CoMo catalyst.
  • hydrorefining catalysts such as a sulfided, alumina-supported CoMo catalyst.
  • the following are normal hydrodesuifurization conditions: temperature ranging from 200 to 420 0 C; pressure from 0.5 to 5.0 MPaG; and LHSV from 1 to 2O h- 1 .
  • the average desired temperature range in the reactive medium is from 200 to 420 0 C, preferably from 240 to 380 0 C, and more preferably from 260 to 320 0 C.
  • the heat released during olefin hydrogenation is undesirable with this process, because it causes the reactor temperature to rise.
  • more than one catalyst bed may be needed, along with injection of hydrogen or a flow of hydrogen and at least one added non- reactive compound, at a lower temperature between the two beds so as to reduce the temperature of the naphtha flow prior to reaching the next bed. Should both beds be necessary, they can also be separated in more than one reactor.
  • process conditions are optimized in order to reduce olefin hydrogenation, consequently releasing less heat.
  • this result is obtained by the presence of at least one added non-reactive compound that inhibits olefin hydrogenation and is also able to accommodate the heat generated in the reactive medium.
  • the pressure in the hydrodesulfurization reactors is preferably between 1.0 and 3.0 MPaG, and more preferably, between 1.5 and 2.5 MPaG.
  • the combination of the addition of at least one non-reactive compound with the HDS in two stages and H 2 S removal can be performed according to different modes.
  • the addition of the at least one non-reactive compound can be carried out in both stages, in the first stage or in the second stage. It could be expected that the mere addition of at least one non-reactive compound in one or both stages of the state-of-the-art HDS naphtha two-stage process, would result in selectivity improvement.
  • the following Examples illustrate that the addition of at least one non-reactive compound or inert compound in the first stage leads to the same or lower selectivity than the two-stage state-of-the-art, without any advantage or process improvement.
  • the addition of at least one non-reactive compound in the second or final stage only shows an improvement as compared to the addition of the at least one non-reactive compound in both reaction stages.
  • the selectivity improvements obtained in the HDS process can be explained on the grounds of the following considerations.
  • the selectivity improvement is reached through (i) reduction of the H 2 S content at the intake of each reactor or reaction stage, this being reached by removing H 2 S in the hydrogen and at least one non-reactive compound stream that is contacted with the olefinic charge, and (ii) separation of one reaction stage into two reaction stages, plus the removal of intermediate H2S.
  • the present invention by combining the removal of a major portion of the formed H 2 S through separation into two stages, plus the addition of at least one non-reactive compound to replace H 2 , makes possible to reduce the H 2 S concentration while at the same time olefin hydrogenation is diminished as a result of lower H 2 concentration.
  • Example 3 of the application shows that the addition of at least one non-reactive compound in the first or initial reaction stage results in the same or lower selectivity than state-of-the-art processes (Example 1).
  • Example 2 the addition of at least one non-reactive compound in the second or final reaction stage only showed improved selectivity as compared to the addition of such non-reactive compounds in both stages (Example 4).
  • the characteristics of the sulfur compounds obtained in the first reaction stage for Examples 1 and 3 were analyzed.
  • Example 1 The temperature conditions of the tests for Examples 1 and 3 were varied so as to obtain the same sulfur content of the HDS product by using H 2 alone (Example 1) and H2 plus at least one added non-reactive compound (Example 3).
  • H 2 alone Example 1
  • H2 plus at least one added non-reactive compound Example 3
  • the percentage of mercaptan compounds from recombination is lower than that from H 2 alone. It is well known that the conversion of mercaptan compounds does not involve any hydrogenation, while thiophenic sulfur removal is more hydrogen- dependent. It is also known that mercaptan compounds are more easily desulfurized than thiophene compounds.
  • the selectivity conquered in the fist stage through the use of at least one added non-reactive compound is lost in view of the need of a deeper severity in the second stage, using H 2 alone, this leading to a higher hydrogenation.
  • the selectivity for this non-desired mode is the same or worse than the two stage HDS state of the art using H 2 alone.
  • both stages contain hydrogen plus at least one added non-reactive compound
  • the final HDS is also more selective even for deeper severity, the process being more selective than the state-of-the-art of two stages and H 2 alone.
  • a preferred range is 1.0 for the first stage (hydrogen only) and between 0.3 and 0.6 for the second stage.
  • a further aspect relates to industrial process set-ups, which can be several.
  • the usual hydrorefining unit configuration involves the recycle of the non- reactive hydrogen downstream the high-pressure separator. To the hydrogen recycle is added the make-up hydrogen, so as to keep the unit pressure at the desired level, replenishing hydrogen consumed in the reactions and lost during H 2 S removal steps and dissolved in the liquid product (in the gas and liquid separators).
  • H 2 S removal can be performed in several ways.
  • H 2 S in the outlet gas of the second stage can be at such a low level that it does not cause any recombination drawback, and thus it can be directed straight to the first reaction stage. Since in the first reaction stage the sulfur content will be higher, H 2 S should be removed from the gas and the liquid product to be directed to the second reaction stage.
  • the outlet gas of the first stage if the non-reactive compound is non-condensable, after H 2 S removal from the effluent said gas can be fed to the second unit and then be recycled to the first reaction stage.
  • the H 2 S removal step from the outlet has of the first stage should be efficient to a degree such that at the intake of the second reaction stage the H 2 S content is lower than 0.05% by volume.
  • the make-up of the at least one added non-reaction compound and hydrogen can be performed in just one or in both stages, or separately in one or another stage , with consequences for the operation conditions in each stage, resulting in small variations in the compositions of the recycle stream in each process step, such modifications being easily determined by the experts.
  • the gas recycles should be independent.
  • the H 2 S removal step is required in the effluents of the first reaction stage, and can be required or not in the effluents of the second reaction stage. This will mainly depend on the sulfur content of the second stage charge, so as to attend to the recommended basis of maximum H 2 S at the reaction stage intake.
  • the at least one added non-reactive compound in the vapor state under condensation conditions downstream of the reactor, are preferably slightly soluble in the product, being kept with hydrogen in the gas recycle, and is preferably directed to H 2 S absorption tower for absorbing H 2 S formed during the HDS reactions. Consumed hydrogen as well as non-reactive gas lost through solubilization into the product in the high-pressure separator should be replenished to allow that the recycle gas composition be kept constant and the recycle compressor work in its optimum operation condition.
  • the addition of the at least one non-reactive compound can be performed intermittently or continuously. Processes for carrying out a recycle are well known in the art. Concentration limits for the content of the compounds dealt with in the present invention can equally be set forth. The compounds can be added or purged so as to keep the desired concentration. A further alternative is the continuous injection and purge of the at least one added non-reactive compound, provided the means for separating hydrogen from said compounds and recycling hydrogen alone are available.
  • the process of the present invention is described below: a) During an initial reaction stage, under hydrodesulfurization conditions and using a reactor charged with a hydrorefining catalyst, contact a naphtha charge with a flow of hydrogen and optionally at least one added non- reactive compound, wherein the H 2 molar fraction falls within the range of 0.2 to 1, and with the H 2 S concentration at the reactor intake limited to not more that 0.1% by volume, to produce an effluent; b) Remove H 2 S from the first-stage reaction effluent to obtain a partially hydrodesulfurized naphtha; and c) Channel the partially desulfurized naphtha from step b) to a second-stage reaction, in a reactor loaded with a second hydrorefining catalyst, under second hydrodesulfurization conditions, and contact this naphtha with a flow of hydrogen and at least one added non-reactive compound, with the H 2 molar fraction ranging from 0.2 to 0.7, and with the H 2
  • the present invention comprises a two-stage hydrodesulfurization reaction, under normal process conditions, wherein the olefinic naphtha charge contacts a hydrorefining catalyst and a flow of hydrogen and at least one added non-reactive compound, with the H 2 S removed between the two reaction stages.
  • nitrogen is used as the added non-reactive compound in the flow of hydrogen and at least one added non-reactive compound.
  • the ratio of the volume of the flow of hydrogen and at least one added non- reactive compound to the volume of the processed charge typically falls between 100 and 1,000 Nm 3 /m 3 , preferably between 200 and 800 Nm 3 /m 3 , and more preferably 300 and 600 NnrVm 3 .
  • the H 2 S concentration is preferably less than 0.05% by volume. Levels higher than 0.1% by volume compromise the selective HDS owing to significant recombination of the H 2 S with the remaining olefins.
  • Any known method can be used to remove the H 2 S from the effluent from the first stage of the reaction. These methods include, but are not limited to condensation, separation, distillation, contacting the counter flowing liquid product with a gas containing no H 2 S, rectification and absorption with a monoethanolamine/diethanolamine (MEA/DEA) solution, adsorption, membranes, and washing with an alkaline solution.
  • condensation separation, distillation, contacting the counter flowing liquid product with a gas containing no H 2 S, rectification and absorption with a monoethanolamine/diethanolamine (MEA/DEA) solution, adsorption, membranes, and washing with an alkaline solution.
  • MEA/DEA monoethanolamine/diethanolamine
  • the H 2 S concentration is preferably less than 0.025% by volume. Levels higher than 0.05% by volume compromise the selective HDS owing to significant recombination of the H 2 S with the remaining olefins.
  • the H 2 S content in the first stage feed should be lower than 1,000 ppmv, and that of the second stage, lower than 500 ppmv.
  • the origin of the mixture of H 2 and the at least one added non-reactive compound is the gas recycle plus the make-up streams, the H 2 S of the first stage product being necessarily removed.
  • the recycle can have origin in the first as well as in the second reaction stage. In case it originates in the second stage and if there is no H 2 S removal section in the first stage, the sulfur content of the second stage charge should be such as not to lead to a H 2 S content higher than 1,000 ppmv in the first stage charge.
  • Possible set-ups for removing H 2 S and recycling flows are well known in the art, and should be selected from those that respond to H 2 S limits of more than 0.1% at the reactor intake, in the first stage of hydrodesulfurization, and 0.05% H 2 S at the reactor intake in the second stage of the reaction.
  • the flow of hydrogen and the at least one added non-reactive compound comes from recycling the hydrodesulfurization effluent gas, or the first or second stage, with which make-up flows of H 2 and the at least one added non-reactive compound are mixed.
  • the recycling of the effluent gas from the reaction and the H 2 S removal step can be separate for each stage, in particular if there are different compositions of the flow of hydrogen and the at least one added non-reactive compound in each reaction stage.
  • Replenishment of the at least one added non-reactive compound in the flow of hydrogen and at least one added non-reactive compound increases when the latter is condensed and solubilized in the liquid effluent from hydrodesulfurization. Losses of said compound can further occur as a consequence of H 2 S removal steps.
  • the at least one added non-reactive compound When the at least one added non-reactive compound is condensed and solubilized in the liquid effluent, it can be removed by distillation or by any separation method, and can also form part of the stream of hydrodesulfurized naphtha recovered in the process, and be added without any harm to the final gasoline composition.
  • the at least one added non-reactive compound is vaporized under condensation conditions, downstream from the reactor, and then mixed with hydrogen to form a recycled gas.
  • Some ways used for making hydrogen can lead to the at least one non- reactive compound to be added to the inventive process.
  • the steam reform designed to obtain the charge for ammonia synthesis units yields a mixture of N 2 and H 2 . It would be possible to process a make-up stream containing N 2 and H 2 . however, if the unit comprises a gas recycle, the composition of the recycle gas varies depending on operation conditions of: (i) the vessels for liquid separation, (ii) the H 2 S removal step, resulting in solubility losses of the recycle gas flow rate and finally (iii) the effective hydrogen consumption in the reactor, this being a function of the operation conditions themselves and being the dominant factor to hydrogen replenishing in the reactor.
  • the preferred condition is therefore to have independent at least one added non-reactive compound and hydrogen make-up streams.
  • the control of the make-up flow rates may be performed so as to make-up the H 2 consumed in the reaction and the lost added non-reactive compound so as to keep the hydrogen molar ratio in the stream of H 2 and the least one added non-reactive compound, the ratio of H 2 and the at least one added non-reactive compound by charge and the pressure at the desired conditions.
  • the recycled gas from the first reaction stage is preferably passed through a stage for removing the H 2 S before returning to the hydrodesulfurization reactor, in order to adjust the H 2 S concentration to a level of less than 0.1% by volume.
  • the means for removing H 2 S from the recycled gas may include, albeit not limited to, absorption units using diethanolamine (DEA) or monoethanolamine (MEA), and washing with an alkaline solution.
  • the concentration of the organosulfurized compounds in the second reaction stage should be such that it does not lead to an increase in H 2 S concentration greater than 0.1% by volume at the reactor intake in the first reaction stage, or 0.05% by volume at the reactor intake in the second reaction stage.
  • a high concentration of H2S present in the reaction mixture causes recombination of the H 2 S with the remaining olefins, forming mercaptanic compounds.
  • hydrodesulfurized naphtha having low sulfur content (preferably lower than 100 ppm) and a low olefin hydrogenation degree, (preferably lower than 40% of the charge original olefins, more preferably, lower than 30% of the original olefins.)
  • a charge of an olefinic naphtha from the catalytic cracking of gasoline was used, without subsequent fractionating, with the following characteristics: sulfur, 1 ,689 mg/kg; olefins, 27.0 mass%; and specific gravity, 0.7598.
  • the naphtha charge was processed in an isothermal hydrodesulfurization reactor, by means of controlled heating zones, loaded with 150 ml_ of a commercial catalyst diluted in 150 ml_ of carborundum.
  • a CoMo commercial catalyst (4.4% CoO and 17.1% MoO 3 ) was used. This catalyst was supported on trilobe AI 2 O 3 , having a diameter of 1.3 mm. The catalyst was sulfided beforehand and stabilized with a directly distilled naphtha prior to processing the olefinic naphtha charge.
  • Hydrodesulfurization is carried out by contacting the naphtha charge with the catalyst and hydrogen gas, in two reaction stages.
  • the charge was processed in the first stage using a pure hydrogen flow and at a temperature controlled at 255 0 C alongside the reactor, with the other conditions fixed as described above.
  • the sulfur concentration was 170 mg/kg, and the olefin concentration was 22.3 mass% in the partially hydrodesulfurized naphtha, equal to a 17.4% hydrogenation of olefins.
  • Table 1 shows the results of the sulfur and olefin concentrations obtained in tests on the recovered hydrodesulfurized naphtha.
  • This Example regards the process of the present invention
  • the hydrodesulfurization reaction is carried out in two stages, using a flow of hydrogen and a added non-reactive compound (nitrogen) only in the second stage.
  • the naphtha charge was processed in the first stage using a pure hydrogen flow and at a temperature controlled at 255 0 C alongside the reactor, with the other conditions fixed as described above.
  • the sulfur concentration was 170 ppm, and the olefin concentration was22.3 mass%, equal to 17.4% hydrogenation of olefins.
  • the partially hydrodesulfurized naphtha was submitted to a second reaction stage wherein the H 2 molar fraction was kept at 0.5 while varying the reaction temperature.
  • Table 2 shows the results for the sulfur and olefin concentrations obtained during testing.
  • This Example regards the process wherein the hydrodesulfurization reaction is carried out in two stages, using a flow of hydrogen and a added non-reactive compound (nitrogen) only in the first stage.
  • the naphtha charge was processed in the first stage using an equimolar mixture of N 2 and H 2 and at a temperature controlled at 272 0 C alongside the reactor, holding to the same sulfur content as in EXAMPLES 1 and 2, and with the other conditions fixed as described above.
  • the sulfur content of the first stage products in the hydrodesulfurization with H 2 (EXAMPLE 1 and 2) and EXAMPLE 3 can be considered as equivalents.
  • the sulfur concentration was 165 mg/kg, and the olefin concentration was 22.5 mass%, equal to 16.9% hydrogenation of olefins.
  • the partially hydrodesulfurized naphtha was submitted to a second hydrodesulfurization reaction stage using only H 2 gas, while varying the reaction temperature.
  • Table 3 shows the results for the sulfur and olefin concentrations obtained during testing.
  • EXAMPLE 4 This Example regards the process of the present invention wherein thehydrodesulfurization reaction is carried out in two stages, using a flow of hydrogen and added non-reactive compound (nitrogen) in both stages.
  • the charge was processed in the first stage using an equimolar mixture of N 2 and H 2 and at a temperature controlled at 272 0 C alongside the reactor, and with the other conditions fixed as described above.
  • the sulfur concentration was 165 mg/kg, and the olefin concentration was 22.5% m/m, equal to 16.9% hydrogenation of olefins.
  • the partially hydrodesulfurized naphtha was submitted to a second reaction stage using a flow of hydrogen and added non-reactive compound (nitrogen) with a molar fraction of 0.5 H 2 , while varying the reaction temperature.
  • Table 4 shows the results for sulfur and olefin concentrations obtained during testing.
  • This comparative Example regards the state of art. Hydrodesulfurization reaction is carried out in one stage, using a flow of hydrogen and a added non- reactive compound.
  • An LHSV of 2 h "1 was used for single-stage testing, equal to the LHSV in the two-stage reaction in EXAMPLES 1 to 4.
  • Figure 1 is a comparison of Examples 1 to 4.
  • the temperature conditions for the first stage for pure hydrogen as well as for the hydrogen and nitrogen flow were set forth to obtain the same level of the sulfur content of the first stage product.
  • First-stage sulfur contents of 170 mg/kg in EXAMPLES 1 and 2 (with pure H 2 ) and of 165 mg/kg in EXAMPLES 3 and 4 (with hydrogen and nitrogen) can be considered to be equal.
  • a lower temperature (255 °C) was required in the HDS with pure hydrogen to reach the same level of HDS using the hydrogen and nitrogen flow at 272 0 C.
  • EXAMPLES 2 and 4 show that in the present invention, when a mixture of H 2 and at least one added non-reactive compound is used under desired conditions in both reaction stages or only the second stage, it is possible to obtain a selectivity level heretofore not attained in the state of the art, represented by EXAMPLES 1 and 5.
  • Comparison of EXAMPLES 2 and 4 shows greater selectivity for hydrogenation using a hydrogen and nitrogen flow only in the second reaction stage. Without limiting the scope of the present invention to a hypothetical effect of nitrogen on selectivity, it is believed that for the same sulfur content in the first stage of hydrodesulfurization using only pure hydrogen, sulfur is present in its mercaptanic form.
  • One HDS route for thiophenic species can involve ring hydrogenation, occurring more extensively with a higher hydrogen concentration.
  • Analyses of sulfur speciation for the first-stage products generated in EXAMPLES 1 to 4 concur with a lower mercaptanic sulfur content in hydrotreatment using the flow of hydrogen and at least one added non-reactive compound, and a higher mercaptan content in HDS using a pure hydrogen flow.
  • the mercaptan species are more readily hydrodesulfurized than the thiophenic type. And, with the flow of hydrogen and at least one added non-reactive compound it is possible to achieve the same final level of HDS, with less olefin hydrogenation. This explains the greater selectivity of EXAMPLE 2 in comparison to EXAMPLE 4, and of both in comparison to EXAMPLE 3.
  • the mercaptan species are more easily converted than the thiophenic ones. Still, having the added non-reactive compound mixed to the hydrogen, it is possible to attain the same level of final HDS, at lower olefin hydrogenation. Therefore it would be important to have more easily desulfurizable compounds for the second HDS stage.
  • the present invention directed to the hydrodesulfurization of cracked naphthas in two stages, with the intermediate H 2 S removal and final treatment under a hydrogen atmosphere and at least one added non-reactive compound, leads to a selectivity level not yet reached in the technique.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

L'invention concerne un procédé d'hydrodésulfuration sélective de naphta contenant des oléfines et de composés organo-soufrés, lequel réduit au minimum l'hydrogénation des oléfines et permet d'obtenir un produit à faible teneur en soufre. Le procédé consiste en une hydrodésulfuration en deux étages, du H2S étant retiré de l'effluent du premier étage. Un flux d'hydrogène ainsi qu'au moins un composé non réactif ajouté sont introduits dans le premier étage, où la fraction molaire H2 est comprise entre 0,2 et 1,0, le H2S à l'admission du réacteur étant limité à un maximum de 0,1 % en volume. Le second étage met en oeuvre un flux d'alimentation d'hydrogène ainsi qu'au moins un composé non réactif ajouté, la fraction molaire H2 allant de 0,2 à 0,7 et le H2S à l'admission du réacteur étant limité à un maximum de 0,05 % en volume.
PCT/GB2006/001567 2005-05-13 2006-04-28 Procede d'hydrodesulfuration selective de naphta WO2006120378A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
ES06726947.2T ES2586567T3 (es) 2005-05-13 2006-04-28 Procedimiento para la hidrodesulfuración selectiva de nafta
MX2007015794A MX2007015794A (es) 2005-05-13 2006-04-28 Procedimiento para la hidrodisulfuracion selectiva de nafta.
DK06726947.2T DK1891183T3 (en) 2005-05-13 2006-04-28 Process for selective hydrodesulfurization of naphtha
EP06726947.2A EP1891183B1 (fr) 2005-05-13 2006-04-28 Procede d'hydrodesulfuration selective de naphta

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BRPI0502040-9A BRPI0502040A (pt) 2005-05-13 2005-05-13 processo de hidrodessulfurização seletiva de nafta
BRPI0502040-9 2005-05-13

Publications (1)

Publication Number Publication Date
WO2006120378A1 true WO2006120378A1 (fr) 2006-11-16

Family

ID=36607572

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2006/001567 WO2006120378A1 (fr) 2005-05-13 2006-04-28 Procede d'hydrodesulfuration selective de naphta

Country Status (7)

Country Link
EP (1) EP1891183B1 (fr)
BR (1) BRPI0502040A (fr)
DK (1) DK1891183T3 (fr)
ES (1) ES2586567T3 (fr)
MX (1) MX2007015794A (fr)
PT (1) PT1891183T (fr)
WO (1) WO2006120378A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0755995A1 (fr) * 1995-07-26 1997-01-29 Mitsubishi Oil Co., Ltd. Procédé de désulfuration d'essence craquée catalytiquement
US5968347A (en) * 1994-11-25 1999-10-19 Kvaerner Process Technology Limited Multi-step hydrodesulfurization process
US6231753B1 (en) * 1996-02-02 2001-05-15 Exxon Research And Engineering Company Two stage deep naphtha desulfurization with reduced mercaptan formation
WO2003099963A1 (fr) * 2002-05-21 2003-12-04 Exxonmobil Research And Engineering Company Hydrodesulfurisation a etapes multiples de flux de naphte au moyen d'un reacteur a lits empiles
WO2005033930A2 (fr) * 2003-10-02 2005-04-14 Exxonmobil Research And Engineering Company Procede de valorisation du naphte

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5968347A (en) * 1994-11-25 1999-10-19 Kvaerner Process Technology Limited Multi-step hydrodesulfurization process
EP0755995A1 (fr) * 1995-07-26 1997-01-29 Mitsubishi Oil Co., Ltd. Procédé de désulfuration d'essence craquée catalytiquement
US6231753B1 (en) * 1996-02-02 2001-05-15 Exxon Research And Engineering Company Two stage deep naphtha desulfurization with reduced mercaptan formation
WO2003099963A1 (fr) * 2002-05-21 2003-12-04 Exxonmobil Research And Engineering Company Hydrodesulfurisation a etapes multiples de flux de naphte au moyen d'un reacteur a lits empiles
WO2005033930A2 (fr) * 2003-10-02 2005-04-14 Exxonmobil Research And Engineering Company Procede de valorisation du naphte

Also Published As

Publication number Publication date
EP1891183B1 (fr) 2016-05-25
DK1891183T3 (en) 2016-09-05
MX2007015794A (es) 2008-03-04
ES2586567T3 (es) 2016-10-17
BRPI0502040A (pt) 2007-01-09
EP1891183A1 (fr) 2008-02-27
PT1891183T (pt) 2016-09-01

Similar Documents

Publication Publication Date Title
US7785461B2 (en) Process for selective hydrodesulfurization of naphtha
EP1857527B1 (fr) Processus d'hydrodésulfuration sélective de flux de naphte
JP4808212B2 (ja) 低硫黄ディーゼル燃料の製造方法
CN101313053B (zh) 具有高温硫醇分解的选择性石脑油加氢脱硫
US7291258B2 (en) HDS process using selected naphtha streams
JP2008127569A (ja) オクタン価の喪失が少ない分解ガソリンの深度脱硫方法
RO120887B1 (ro) Procedeu pentru hidrodesulfurarea compuşilor nafta
JP4423037B2 (ja) 段間分留を伴う分解ナフサ流の多段水素化脱硫
JP2010174247A (ja) ナフサ脱硫を増大するためのｃｏの低減
CN102125846A (zh) 一种硫醇醚化催化剂
US20150175910A1 (en) Process for the production of a light gasoline with a low sulphur content
KR101533584B1 (ko) 가스 스트림으로부터 메르캅탄의 제거를 위한 티오에테르화 프로세스
US20040178123A1 (en) Process for the hydrodesulfurization of naphtha
KR20230002026A (ko) 수소 정제를 수반한 수소처리 재순환 가스 스트림에서의 황화수소의 직접 산화
EP1891183B1 (fr) Procede d'hydrodesulfuration selective de naphta
US7361265B2 (en) Process for the selective hydrodesulfurization of olefinic naphtha streams
US6984312B2 (en) Process for the desulfurization of light FCC naphtha
US10443001B2 (en) Removal of sulfur from naphtha
WO2000058420A1 (fr) Hydrotraitement

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

WWE Wipo information: entry into national phase

Ref document number: 2006726947

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: MX/a/2007/015794

Country of ref document: MX

NENP Non-entry into the national phase

Ref country code: RU

WWW Wipo information: withdrawn in national office

Country of ref document: RU

WWP Wipo information: published in national office

Ref document number: 2006726947

Country of ref document: EP