JP4938278B2 - Process for selective desulfurization of olefin gasoline including hydrogen purification process - Google Patents

Abstract

Hydrodesulfuration of a hydrocarbon cut(HC) containing at least 5% of olefins in wich the cut is mixed with a hydrogen supply(HYD) and recycled hydrogen(REC) at the inlet to the reactor.The reactor contains a desulfuration catalyst in conditions enabling transformation of sulfur compounds to hydrogen sulfide ; a purification process may be effected on the HYD/REC supply so that the overall charge comprises no more than 50 vppm of carbon monoxide and at least 120 vppm of carbon monoxide + 1/2 carbon dioxide.

Description

The present invention relates to a process for producing hydrocarbons with a low sulfur content. The present invention is primarily applicable to hydrocarbon mixtures containing generally more than 5 wt% olefin fraction and usually more than 10 wt% sulfur and at least 50 wtppm sulfur. This method allows hydrogen with a very low CO content but a relatively high CO ₂ content to be used without significantly affecting the performance of the catalyst used during the hydrodesulfurization process. This allows for diversification of possible makeup hydrogen sources and / or simplifies hydroprocessing without relying on removing large amounts of CO ₂ .

  According to future specifications for vehicle fuels, a considerable reduction in the sulfur content of such fuels, especially gasoline, is foreseen. In Europe, the specification for sulfur content is 150 ppm by weight and will fall to a level below 10 ppm via the 50 ppm level in the coming years. Therefore, it is necessary to develop a new method for intensive desulfurization of gasoline due to changes in the sulfur content specification.

  The main sulfur source, based on gasoline, is the gasoline fraction derived from catalytic cracking of cracked gasoline, mainly atmospheric distillation residue or crude oil vacuum distillate. Up to 90% of the sulfur content in gasoline is caused by gasoline fractions from catalytic cracking (representing an average of 40% on a gasoline basis). As a result, in order to produce gasoline with a low sulfur content, a process for desulfurizing the catalytically cracked gasoline is required. Conveniently, the relevant desulfurization is carried out using one or more steps in which a sulfur-containing compound contained in the gasoline is contacted with a catalyst in the presence of a gas rich in hydrogen in a process called hydrodesulfurization. Is called.

  Furthermore, the octane number of such gasoline is very high due to its high olefin content. In order to maintain the octane number of such gasoline, it is necessary to limit the reaction in which the olefin is converted to paraffin. Such a hydrogenation reaction is inherent to the hydrodesulfurization method, and as a result, the octane number can be lost as much as 5 to 10 mainly due to the reduction of the olefin content.

Furthermore, in refineries, gasoline hydrodesulphurization processes are often provided for gasoline fractions directly at the outlet from crackers, such as catalytic crackers, which are normally driven continuously for several years. For this reason, the hydrodesulfurization process must be operated for 3-5 years without interruption. The activity and amount of catalyst used to convert sulfur to H ₂ S must be high so that it can be operated continuously over several years.

In order to withstand competition, hydrodesulfurization processes have two main constraints:
-Restricted olefin hydrogenation;
-The good stability of the catalyst system and continuous operability over several years must be met.

The hydrodesulfurization process is based on treating the hydrocarbon fraction with a catalyst comprising a non-noble metal sulfided and supported on an inorganic support in the presence of hydrogen. The metals used generally include at least one metal from group VIII of the periodic table (eg, cobalt) and optionally a metal from group VIB (eg, molybdenum). The most commonly used catalyst formats are based on Co and Mo or Ni and Mo supported on alumina. When processing olefin gasoline from crackers, the catalyst and operating conditions are optimized to limit the extent of olefin hydrogenation while maximizing the conversion of sulfur-containing organic compounds to H ₂ S. Such a method is described in Patent Documents 1 and 2 in particular.

The hydrodesulfurization process may use hydrogen from a number of sources. The primary hydrogen source in the refinery is hydrogen from catalytic reforming. Catalytic reformers produce hydrogen during the dehydrogenation of naphthenes to aromatics and dehydrocyclization. The hydrogen is a generally 60% to 90% purity, substantially free of CO and CO _2.

Depending on the requirements of the refinery, hydrogen may be produced by steam reforming of light hydrocarbons or partial oxidation of various hydrocarbons, particularly heavy residues. Steam reforming consists of converting light hydrocarbon feedstock to synthesis gas (mixture of H ₂ , CO, CO ₂ , CH ₄ and H ₂ O) by reaction with steam with a nickel-based catalyst. The production of hydrogen by partial oxidation consists of a step of producing a synthesis gas composed of CO, CO ₂ , H ₂ and H ₂ O by treating the hydrocarbon fraction by high temperature oxidation using oxygen. In the last two cases, the production of hydrogen is accompanied by the production of carbon oxide, which is usually substantially removed either by methanation or adsorption. However, the remaining amount of carbon oxides (CO and CO ₂ ) may be greater than 50 ppmv, or greater than 100 ppmv in some cases. Although other hydrogen sources such as hydrogen derived from catalytic cracking gas may be used, hydrogen derived from catalytic cracking gas contains substantial amounts of CO and CO ₂ . Finally, CO and CO ₂ may in some cases be supplied by the hydrocarbon feedstock itself in the form of a dissolved gas if the feedstock comes in contact with trace amounts of upstream gas.

Accordingly, hydrogen from the reaction zone of hydrogen and a hydrogenation process from refinery might contain CO and CO ₂ various amounts. The most widely used technique when hydrogen containing CO and CO ₂ is used or produced is to completely remove these impurities, typically by PSA (pressure swing adsorption). However, the technology is expensive and consumes some of the available hydrogen.
European Patent No. 01031622 European Patent No. 01250401

  One of the objects of the present invention is to select a hydrotreating process, particularly an olefin fraction (typically gasoline), using a wider variety of hydrogen sources and typically performing a milder refining process. The successful operation of the hydrotreating process for efficient desulfurization.

  Another object of the present invention is to reduce hydrogen consumption by reducing the hydrogen purge flow rate (purging of a part of the recirculated gas around the hydrodesulfurization reactor) in the hydrotreating process.

In the course of research conducted by the present applicant, the activity of the hydrodesulfurization catalyst is greatly reduced by the presence of CO even in amounts of 100 ppmv (part per million by volume), 50 ppmv or 20 ppmv. It was discovered that Furthermore, it has been found that the presence of CO hardly affects the olefin hydrogenation reaction rate. For this reason, when the catalyst capacity is increased during the hydrodesulfurization step to maintain the degree of desulfurization, the presence of CO in the hydrogen results in a reduction in catalyst activity and a significant loss of octane number. It becomes. The decrease in activity may be compensated by increasing the temperature, in which case the life of the catalyst is affected. Similar observations were reported in US patent application 2003/0221994. According to this patent application, the selective hydrodesulfurization process prohibits the sum of (CO + 1 / 2CO ₂ ) (hereinafter referred to as COx) from exceeding 100 ppmv in a hydrocarbon and hydrogen mixture. It is recommended to use hydrogen containing an amount of carbon oxide.

Surprisingly, however, the Applicant has shown that, in contrast, the amount of CO ₂ is large without significant effects, although the CO content is a parameter directly linked to substantial inhibition of the desulfurization catalyst. I found that it could fluctuate. To oxidize CO to CO ₂ but to overcome the detrimental effects of pre-treatment process of the hydrogen comprises the step of not extract the CO ₂ formed was such that, carbon oxides also be CO ₂ content of greater than 200ppmv It was also found to get. Saving the cost of an expensive process for almost complete removal of CO ₂ is a huge advantage while opening up the possibility of using a low purity hydrogen source. For this reason, the present invention presents a process for desulfurizing hydrocarbon fractions that are compatible with a very low CO content but a substantial COx content. This method preferably includes a step of selectively oxidizing CO contained in hydrogen to CO ₂ and a step of hydrodesulfurization, and the two steps are typically formed continuously. This is carried out without intermediate extraction of the CO _{2 formed} . This proposal has the advantage over prior art methods in that it uses a simple and inexpensive solution to overcome the problems associated with the inhibition of hydrodesulfurization catalysts by carbon oxides.

The main methods for removing a considerable amount of CO are the method of oxidizing CO to CO ₂ (this method is preferred in the present invention) and the method of methanation of CO (methanation).

The main method of oxidizing CO to CO ₂ is a steam conversion reaction (this steam conversion reaction can convert CO to CO ₂ by reaction with steam carried out for example by a nickel-based catalyst) or oxygen. Selective oxidation of CO used to CO ₂ . This second option (most preferred in the present invention) is described in more detail in this application.

Methods for selectively oxidizing CO to CO ₂ using oxygen are described in the literature. For example, international patent application WO01 / 0181242 may be cited. This document proposes a method for purifying hydrogen based on oxidizing CO to CO ₂ using a material having a thermal conductivity of more than 30 W / m · K in order to improve the selectivity of the reaction. US Pat. No. 5,789,337 describes a method of synthesizing a catalyst comprising finely dispersed gold on a support with increased activity. International patent application WO 00/17097 recommends the use of a catalyst comprising ruthenium or platinum or a mixture of these two elements supported on an α-alumina based support.

The present invention is a hydrodesulfurization process for a hydrocarbon fraction containing at least 5% by weight of an olefin, wherein the hydrocarbon fraction, a HYD stream of make-up hydrogen and optionally a REC stream of recycled hydrogen are mixed sulfur-containing organic compound of fraction a method of forming the entire feedstock to be supplied to the inlet to at least one reactor containing a hydrodesulfurization catalyst under the operating conditions that can be converted into H _{2 S,} to form a HYD flow One or more hydrogen sources are selected and at least one hydrogen refining process is suitably performed on HYD, REC or mixtures thereof, so that the total feedstock is at most 50 ppmv CO and at least 120 ppmv COx ( Here, COx = CO + 1 / 2CO ₂ ).

  In the method of the present invention, one or more hydrogen sources that form a HYD stream are selected and at least one hydrogen purification process is performed on at least a portion of the HYD so that the HYD is at most 50 ppmv CO 2. And at least 120 ppmv COx.

In the method of the present invention, including at least one hydrorefining treatment T1 performed on HYD, REC, or a mixture thereof, the treatment T1 includes CO ₂ limited to obtain at least 200 ppmv CO ₂ in the total feedstock. It is preferable to perform ₂ removal.

In the method of the present invention, including at least one treatment T2 for purifying hydrogen, which is performed on HYD, REC and a mixture thereof, the treatment T2 obtains at most 50 ppmv CO in the whole feedstock. It is preferable to perform catalytic oxidation of CO with O ₂ and / or H ₂ O.

In the method of the present invention, including at least one treatment T3 for purifying hydrogen, which is performed on HYD, REC or a mixture thereof, the treatment T3 obtains at most 50 ppmv of CO in the whole feedstock. It is preferable to perform catalytic methanation of CO with H ₂ .

The method of the present invention includes a hydrogen purification process performed on HYD and optionally REC or a mixture thereof, the process performing a process T2 that performs catalytic oxidation of CO with O ₂ and then directly and secondary Preferably, the desulfurization of the hydrocarbon fraction in the presence of the purified hydrogen stream is carried out without a typical CO ₂ removal.

In the process of the present invention comprising a hydrogen purification treatment T3 performed on HYD and optionally REC or a mixture thereof, the treatment T3 performing CO methanation with H ₂ and then directly and secondary without the CO ₂ removal, it is preferred to include performing the desulfurization of hydrocarbon fractions in the presence of purified hydrogen stream.

In the method of the present invention, it is preferable to include a treatment T1 for removing CO ₂ which is performed on the HYD upstream of T2 or T3.

  The method of the present invention includes a hydrogen recycle REC and a purge of recirculated hydrogen WGAS, and the flow rate of the purge WGAS has a CO content of less than 50 ppmv in the entire feedstock, but a COx content in the entire feedstock of 120 ppmv. It is preferable to be controlled so as to exceed.

  In the process of the invention described above, the hydrodesulfurization of the olefin gasoline fraction is carried out using a catalyst comprising at least one element from group VIII and optionally an element from group VIB. The element is selected from the group consisting of nickel, cobalt and iron, the optional Group VIB element is molybdenum or tungsten, the reactor pressure is 0.5-5 MPa, and the hydrogen flow rate (per hour) The ratio of hydrogen (standard liters) to hydrocarbon flow rate (liters per hour) is preferably 50-800 and the temperature is preferably 200-400 ° C.

  In the method of the present invention, the catalyst preferably contains cobalt and molybdenum.

In the present invention, at least one hydrogen refining treatment is appropriately performed on HYD, REC, or a mixture thereof, so that the supplementary hydrogen at the inlet to the catalytic reactor and / or the CO content of the entire feedstock is 50 ppmv or less. , The COx (= CO + 1 / 2CO ₂ ) content can exceed 120 ppmv, which can be diversified with respect to the source of make-up hydrogen and / or simplify the hydrogen purification process, and Alternatively, hydrogen purge from the hydrodesulfurization apparatus can be reduced.

The present invention is a process for hydrodesulfurizing a hydrocarbon fraction using a make-up hydrogen source, generally recycled hydrogen, and has a high CO content in the entire feedstock at the inlet to the hydrodesulfurization reactor. At least 50 ppmv, preferably at most 20 ppmv, more preferably at most 10 ppmv, while the amount of COx (= CO + 1/2 CO ₂ ) is at least partly time (eg at least 30% or 50% of time, preferably Over 120 ppmv over 100% of action time). The amount of COx is generally less than 10,000 ppmv and usually less than 5000 ppmv. Typically, the COx content is 120 to 1000 ppmv, more preferably 120 to 500 ppmv. The method of the present invention does not exclude the case where the COx content is less than 120 ppmv or less than 50 ppmv during part of the time. This can occur, for example, when a “clean” hydrogen source that is substantially free of CO and CO ₂ is available in sufficient quantities to supply various consumer devices (this has been treated Depending on the nature of the crude oil).

More particularly, the present invention is a process for hydrodesulfurizing a hydrocarbon HC fraction containing at least 5% by weight of an olefin, said hydrocarbon fraction, a HYD stream of make-up hydrogen (stream HYD) and generally A recycled hydrogen REC stream (stream REC) is mixed and fed to the inlet to at least one reactor containing a desulfurization catalyst under operating conditions that can convert the sulfur-containing organic compounds of the hydrocarbon HC fraction to H ₂ S. One or more hydrogen sources that form the entire feedstock and form the HYD stream are selected, and in some cases at least one hydrogen for the HYD stream, the REC stream (or part of the REC), or a mixture thereof As a result of the refining process, the entire feedstock contains at most 50 ppmv CO and spans at least an integral part of the time. A method comprising at least 120 ppmv COx.

Preferably, said purity conditions consistent with the present invention: (at most 50 ppmv CO [or 20 or 10 ppmv] and at least 120 ppmv COx over at least an integral part of the time) are also relative to the HYD stream of make-up hydrogen can get. The best amount of make-up hydrogen in the present invention has a very low CO content (less than 10 ppmv, preferably less than 5 ppmv) and a high CO ₂ / CO ratio (eg greater than 5 or 10, eg 5-60 ).

In addition, when using a hydrogen recycle REC stream around the hydrodesulfurization unit, a WGAS purge stream is also used to prevent accumulation of impurities. Loop hydrogen tends to concentrate the CO and CO _2. The present invention, as a result, receiving a large amount of CO _2, thus, the present invention may increase the REC / HYD recycle ratio. This may be greater than 4 or may be 6-30. As a result, the required hydrogen purge WGAS is reduced. Advantageously, the purge ratio is controlled so that the CO content in the entire feedstock is less than 50 ppmv, preferably less than 20 ppmv, but the COx content in the overall feedstock is greater than 120 ppmv.

The method typically includes at least one treatment T1 for purifying hydrogen, performed on HYD, REC or mixtures thereof. This treatment T1 provides limited CO ₂ removal, which results in a CO ₂ content of the entire feedstock of at least 200 ppmv.

Preferably, the method comprises at least one treatment T2 for purifying hydrogen, performed on HYD, REC or mixtures thereof. This treatment T2 performs catalytic oxidation of CO with O ₂ and / or H ₂ O, whereby the resulting CO is at most 50 ppmv (preferably at most 20 ppmv) in the entire feedstock.

  Oxidation may be performed by steam CO conversion. This steam CO conversion is known as shift conversion and may be performed in one or two steps.

Preferably, the method comprises a hydrogen purification process carried out on HYD and optionally REC (or part of REC) or mixtures thereof. This treatment includes treatment T2, which performs catalytic oxidation of CO with O ₂ (preferential oxidation of CO with hydrogen present), and then purified hydrogen without direct and secondary CO ₂ removal. Desulfurization of the hydrocarbon HC fraction in the presence of a stream. It is also possible to combine steam conversion with final preferential oxidation, typically at low temperatures.

In a variant, the method may comprise at least one treatment T3 for hydrogen purification performed on HYD, REC or mixtures thereof. This treatment T3 performs catalytic methanation of CO with H ₂ , and the resulting CO is at most 50 ppmv in the entire feedstock. In this case, the method typically includes a hydrogen purification process performed on HYD and optionally REC or mixtures thereof. This treatment, including T3, performs CO methanation with H ₂ and then desulfurizes the hydrocarbon HC fraction in the presence of a purified hydrogen stream without direct secondary CO ₂ removal. . Although methanation also tends to remove CO ₂ , the methanation conditions ensure that the entire feedstock still contains significant amounts of CO ₂ (and possibly more than 120 ppmv COx) and / or feedstock. it may be combined with the presence of dissolved CO ₂ in the.

Preferably, the method comprises a hydrogen purification process carried out on HYD and optionally REC (or part of REC) or mixtures thereof. This treatment includes treatment T2, which results in the catalytic oxidation of CO with O ₂ , followed by desulfurization of hydrocarbon HC fractions in the presence of a purified hydrogen stream without direct and secondary CO ₂ removal. I do.

Often, the method, in order to remove most of the CO _2, is performed for the upstream HYD of T2 or T3, including preliminary treatment T1 for eliminating CO _2.

As an example of make-up hydrogen production, steam reforming followed by 1 or 2 to obtain hydrogen with low residual CO content (eg 2000-5000 ppmv) and low CO ₂ content (50-1000 ppmv) Methane may be treated by one steam CO conversion step and one CO ₂ removal step T1 (eg, by washing with a methyldiethanolamine solution). This hydrogen may then be treated by a preferential oxygen oxidation treatment T2 (or steam conversion followed by preferential oxidation), preferably with a CO content of less than 10 or less than 5 ppmv and a CO ₂ content At a flow rate suitable to obtain a final make-up hydrogen that is between 120 and 1000 ppmv with other very pure hydrogen sources (substantially free of CO and CO ₂ , hydrogen from catalytic reforming) Mix.

Steam conversion, supplemental technical features of CO ₂ removal by methanation and amine washing process (or other adsorption liquid), see article by P Leprince "Procedes de transformation" [ "Transformation process"], Technip, the publishers ( Paris), 1998, p476-490.

(Description of preferred preferential CO oxidation treatment using oxygen)
Many catalysts based on supported or unsupported noble metals can catalyze the oxidation of CO to CO _{2 in} the presence of oxygen. However, in the presence of hydrogen, a catalyst that does not convert too much hydrogen to water must be used. For this reason, the use of selective catalysts for the preferential oxidation of CO is a very important solution to the problem of hydrogen purification. However, a very high degree of selectivity is not necessarily required, and in the context of the present invention, the presence of a slight amount of steam in the hydrogen purified by the preferential oxidation catalyst indicates the selective hydrogenation of olefin gasoline. The use of hydrogen in the desulfurization process is not completely denied. The amount of H ₂ S contained in the hydrogen should generally not exceed 10 ppmv (volume ppm) and is preferably 1 ppmv before the preferential oxidation step. The copper strip test (well known to those skilled in the art) must be negative. For this reason, the hydrogen sulfide hydrogen may be purified by any method known to those skilled in the art. Examples that may be cited are processes for adsorption, extraction or amine washing processes or chemical conversion of H ₂ S. This list in no way limits the processing that may be used in the present invention.

The step of preferentially oxidizing CO of the present invention to CO ₂ may be performed, for example, with a selective catalyst in the presence of hydrogen. The metal that may be used to carry out this reaction may be selected from the group formed by the noble metals Pt, Pd, Ru, Rh, Ir, Au or Cu, Cr, Mn and Ce. The metals may be used alone or in combination with other metals, or they may form an alloy. Even if they are used in bulk metal form (filament, foam, sponge, etc.), they can be alumina, cerium oxide (cerine), splenite, gold cordite, zirconia, silica, iron oxide (α-Fe _It may be supported on a porous refractory oxide such as ₂ O ₃ ) or zinc oxide. Regardless, without limiting the scope of the present invention, the preferential CO oxidation step of the present invention may be performed on a finely distributed gold-based catalyst on iron hydroxide. Such catalysts may be prepared using the method described in the publication “J Catal” by Haruta et al., 1993, 144, p175, but it is also possible to use any other draft described in the literature. May be used to prepare.

The catalyst is prepared, for example, by co-precipitation of a solution containing HAuCl ₄ · 3H ₂ O and Fe (NO ₃ ) ₃ · 9H ₂ O and a solution containing sodium carbonate. These two solutions are added gradually and then stirred vigorously in a precipitation reactor containing distilled water. The reaction mixture is maintained at 80 ° C. while the two solutions are added, and the pH is maintained between 8 and 8.5 throughout the operation. After filtration, the precipitate is washed with hot water until the washings are free of chlorine (monitored by the silver nitrate reaction) and then dried in a vacuum oven at 40 ° C. for 12 hours. The obtained powder is then calcined at 400 ° C. for 2 hours in dry air at an air flow rate of 0.5 L / g (catalyst) / h. After grinding, a powder having an average particle size (granulometry) of around 20 μm and a surface area of 60 m ² / g is obtained. The catalyst contains 3% by weight of Au.

  The catalyst may be formed using all of the methods known to those skilled in the art, a non-limiting example that may be cited is a hollow cornerstone using a wash coat. (Monolith) Supports, granules, extrudates, etc.

(Description of hydrodesulfurization process)
The hydrodesulfurization step is carried out on a catalyst comprising at least one element from group VIII, preferably an element from group VIII and an element from group VIB. The element from group VIII is selected from the group consisting of nickel, cobalt and iron. If present, the element from group VIB is preferably molybdenum or tungsten. The metal is supported on an amorphous solid support selected from the group consisting of silica, silicon carbide and alumina and is formed in the form of beads or extrudates. In order to selectively hydrodesulfurize the carbonaceous fraction containing olefins, it is preferred to use a catalyst comprising cobalt and molybdenum on an alumina-based support.

The hydrodesulfurization step advantageously comprises a first hydrodesulfurization step capable of converting more than 50% of the sulfur present in the feedstock to H ₂ S, and saturated sulfur by a catalyst comprising a metal from Group VIII. It may be performed in two steps, a final step constituted by either a step of hydrocracking the contained compound or a step of hydrodesulfurizing with a catalyst having lower activity than the catalyst of the first step. This type of linkage can improve the hydrodesulfurization selectivity.

The catalyst or catalysts used during this step are in a sulfurized form. The sulfidation procedure may be performed in-situ or off-site. In the former case, the catalyst is sulfided prior to loading into the reactor, while in the latter case, the catalyst is loaded into the reactor in the form of a metal oxide, and H ₂ S or cracked to H sulfide is carried out in a reactor by injecting can be a _{2 S} compounds (e.g. DMDS and hydrogen). Any conventional sulfidation method used by those skilled in the art that can sulfidize at least 50%, preferably 70% of the metal oxide supported on the support may be used.

  The reactor pressure is generally 0.5-5 MPa and the hydrogen flow rate is preferably 50-800, preferably the ratio of hydrogen flow rate (standard liters per hour) to hydrocarbon flow rate (liters per hour). Is 60-600. Depending on the amount of sulfur in the hydrocarbon fraction to be desulfurized, the temperature is 200 to 400 ° C., preferably 230 to 350 ° C.

(Example 1: Comparison)
A pilot apparatus constituted by a reactor having a capacity of 200 ml was charged with 100 ml of a commercial HR806S catalyst sold by AXENS. This catalyst is based on cobalt and molybdenum supported on alumina and is supplied in a pre-sulfided form, thus eliminating the need for a subsequent sulfidation step prior to contact with the feedstock. The feedstock to be treated was gasoline A from the catalytic cracker. This gasoline was depentanized to treat only the C ₆ + fraction by hydrodesulfurization. The feedstock contained 425 ppm sulfur, 6 ppm sulfur was in the form of thiols, and the bromine index measured using the ASTM D1159-98 method was 49 g / 100 g. The cut point of gasoline A was determined by simulation distillation, and gasoline A had a cut point of 61 ° C. of 5% by weight and a cut point of 229 ° C. of 95% by weight.

Gasoline A was mixed with pure hydrogen and injected into the reactor. The pressure is maintained at 2.1 MPa, the flow rate of the feedstock is 400 ml / h, the hourly space velocity (HSV) represents 4h ⁻¹ , the hydrogen flow rate is 120 liters / h, It represented a flow rate of 300 (standard) liters / liter of feedstock. Three different temperatures were tested.

  The apparent selectivity of the catalyst for each temperature point is the ratio of the apparent first order rate constant between the desulfurization rate and the olefin hydrogenation rate. As calculated.

The sulfur content and olefin content as measured by bromine number and selectivity are shown in Table 1.

(Example 2: comparison)
To determine the effect of CO and CO ₂ for catalyst performance, with 1 hydrogen cylinder content including 10 0 ppmv of CO and 350ppmv of CO _2. This hydrogen was mixed with gasoline at the same flow rate as in Example 1. CO content of the mixture formed in this way is 65Ppmv, CO ₂ content was 228Ppmv. The operating conditions were the same as in Example 1. Table 2 shows the results of the test.

The presence of 65 and 228 ppmv of each amount of CO and CO _{2 in} the hydrogen and gasoline A mixture reduced the performance of the hydrodesulfurization activity of the catalyst. In contrast, hydrogenation activity was substantially unaffected, which reduced selectivity.

(Example 3: According to the present invention)
Example 3 is consistent with the present invention, ie, the hydrogen containing CO and CO ₂ used in Example 2 was pretreated to oxidize CO to CO ₂ . Oxidation was performed by mixing hydrogen and oxygen and treating this mixture with an oxidation catalyst. Hydrogen was mixed with a pure oxygen stream and the flow rate was adjusted so that the molar ratio between oxygen and CO was 1.1. The reactor was operated at a pressure of 2.1 MPa around ambient temperature (50 ° C.).

The preparation of the catalyst is, for example, by co-precipitation of a solution containing HAuCl ₄ .3H ₂ O and Fe (NO ₃ ) ₃ .9H ₂ O and a solution containing sodium carbonate. These two solutions were gradually added to the precipitation reactor containing distilled water and then stirred vigorously. The reaction mixture was maintained at 80 ° C. throughout the addition of the two solutions and the pH was maintained between 8 and 8.5 during the entire operation. After filtration, the precipitate was washed with hot water until the wash water was free of chloride (monitored by reaction with silver nitrate) and then dried in a vacuum oven at 40 ° C. for 12 hours. The obtained powder was calcined at 400 ° C. for 2 hours at an air flow rate of 0.5 L / catalyst g / hydrogen in dry air. After pulverization, a powder having an average particle size of around 20 μm and a specific surface area of about 60 m ² / g was obtained. The catalyst contained 3% by weight of gold. Using the Au [III] peak, 60-mm gold particles could be measured by X-ray diffraction analysis. The catalyst (100 mg, diluted 1:20 with α-Al ₂ O ₃ ) was then placed in a stainless steel reactor with an internal diameter of 10 mm and encapsulated heated to 50 ° C. Inserted into a tubular oven. The hydrogen flow rate was adjusted to 5 × 10 ⁴ Nml / h / g (catalyst), so that the space velocity per hour was 5 × 10 ⁵ h ⁻¹ . The density of the catalyst was 1 g / cm ³ . Analysis of the gas and effluent entering the reactor (CO, CO ₂ , H ₂ O, O ₂ ) was performed by gas chromatography with two catharometric detectors.

After passing hydrogen through the preferential oxidation catalyst under the conditions described, the stabilized CO and CO ₂ contents in the treated hydrogen were 17 ppmv and 430 ppmv, respectively.

Pressurized hydrogen gas in a cylinder containing about 17 ppmv CO and 430 ppmv CO ₂ was produced, yielding the following results. The gas containing these was then mixed with gasoline A and sent to the reactor used in Examples 1 and 2 under the same operating conditions. CO content of the thus configured mixtures are 11ppmv, CO ₂ content was 283Ppmv. Table 3 shows the results of this test.

By performing the oxidation step to pre-treat the hydrogen, the hydrodesulfurization activity of the catalyst is significantly improved, and the production activity and selectivity are carried out with CO and CO ₂ free hydrogen as described in Example 1. The test results are the same.

As a result, by using the CO oxidation pretreatment process with a simple device, no matter how large the CO ₂ need be removed, in the performance of hydrodesulfurization catalyst due to the presence of CO in hydrogen. Harmful effects can be considerably limited.

Claims (11)

A hydrodesulfurization a hydrocarbon fraction containing at least 5 wt% of the olefin, the hydrocarbon fraction, REC stream HYD stream your good beauty recycle hydrogen makeup hydrogen is mixed, the sulfur-containing hydrocarbon fractions organic compounds a method of forming the entire feedstock to be supplied to the inlet to at least one reactor containing a hydrodesulfurization catalyst under the operating conditions that can be converted into H _{2 S,}
HYD stream one or more of the hydrogen source to be formed is selected to, at least one hydrogen purification treatment HYD, with the REC or a mixture thereof cracking line, as a result, at the inlet to the hydrodesulphurization reactor, wherein at most the entire feedstock 50 ppmv CO and at least 120ppmv of COx (here, COx = CO + 1 / 2CO 2) including, method.   One or more hydrogen sources that form a HYD stream are selected and at least one hydrogen purification process is performed on at least a portion of the HYD so that the HYD includes at most 50 ppmv CO and at least 120 ppmv COx. The method of claim 1. HYD, wherein at least one hydrogen purification treatment T1 carried out on REC or a mixture thereof, the process T1 performs a limited CO ₂ elimination to obtain a CO ₂ for at least 200ppmv throughout feedstocks claim The method according to 1 or 2. Including at least one treatment T2 to purify hydrogen, performed on HYD, REC, and mixtures thereof, wherein the treatment T2 includes O ₂ and / or H to obtain at most 50 ppmv CO in the total feedstock. _{The method} according to claim 1, wherein the catalytic oxidation of CO with ₂ O is performed. Including at least one treatment T3 to purify hydrogen, performed on HYD, REC or mixtures thereof, wherein the treatment T3 is a catalyst for CO with H ₂ to obtain at most 50 ppmv CO in the total feedstock 4. The method according to any one of claims 1 to 3, wherein an effective methanation is performed. Contains hydrogen purification treatment carried out on HYD and R EC or a mixture thereof, the process performs a process T2 for performing catalytic oxidation of CO by O _2, then directly and secondary CO ₂ removal 5. A process according to claim 4, comprising desulfurizing the hydrocarbon fraction in the presence of a purified hydrogen stream without performing. Includes HYD and R EC or hydrogen purification treatment T3 carried out on mixtures thereof, said process T3 performs methanation of CO by H _2, followed by performing the direct and secondary CO ₂ removal 6. The process of claim 5, comprising desulfurizing the hydrocarbon fraction in the presence of a purified hydrogen stream. The method according to claim 6 or 7, comprising a process T1 for removing CO ₂ performed on HYD upstream of T2 or T3.   Including a hydrogen recycle REC and a purge of recirculated hydrogen WGAS, the purge WGAS flow rate is controlled such that the CO content in the entire feedstock is less than 50 ppmv, but the COx content in the entire feedstock is greater than 120 ppmv The method according to any one of claims 1 to 8. For hydrodesulfurization of an olefin gasoline fraction, line using a catalyst containing at least one element and the element from group VIB of the catalyst or Group VIII comprising at least one elemental from group VIII We, the element from group VIII is selected from nickel, from the group constituted by cobalt and iron, elemental group VIB is molybdenum or tungsten, the pressure in the reactor is 0.5 to 5 MPa, the hydrogen flow rate 10. The ratio of (standard liters of hydrogen per hour) to hydrocarbon flow rate (liters per hour) is 50 to 800, and the temperature is 200 to 400 [deg.] C. Method.   The method of claim 10, wherein the catalyst comprises cobalt and molybdenum.