JP5581396B2 - Method for removing arsenic using a capture catalyst prior to desulfurization - Google Patents

Description

  The present invention relates to a process for producing naphtha boiling range products having improved properties.

  One prior art technique for treating cracked naphtha involves performing selective hydrodesulphurization of cracked naphtha. Selective hydrodesulfurization refers to a process in which sulfur is removed from naphtha while minimizing the amount of olefin saturation that occurs during the reaction. Avoidance of olefin saturation can be valuable as it leads to higher octane naphtha products. Maintaining a higher octane number allows the selectively hydrodesulfurized feedstock to be used as a naphtha fuel stock without the need for a reforming process.

  One type of naphtha feedstock having a suitable octane number for use without modification is a naphtha feedstock produced by a fluid catalytic cracking (FCC) process. FCC naphtha feeds contain significant amounts of olefins, making selective hydrodesulfurization processes an attractive option. However, depending on the type of feed supplied to the FCC process, the resulting FCC naphtha feed may also contain a substantial amount of arsenic. Arsenic is a known catalyst poison for many hydrodesulfurization catalysts.

  Arsenic scavenging catalysts are commercially available to mitigate the effects of excess arsenic in the feed. In the present invention, such an arsenic scavenging catalyst can be packed at or near the top of the catalyst bed for the hydrodesulfurization process. The arsenic capture catalyst functions to sequester arsenic from the feedstock, thereby reducing or even preventing arsenic from reaching the hydrodesulfurization catalyst and then poisoning it.

  One aspect of the present invention is a method for selectively hydrotreating a naphtha boiling range feedstock, comprising the step of supplying a naphtha boiling range feedstock containing at least about 5 wt% olefin and at least about 1 ppb arsenic. Including. The continuous hydrodesulfurization process (or method) continuous run time and product sulfur content can then be identified. Furthermore, a first effective selective hydrodesulfurization condition can be determined for selectively hydrodesulfurizing a naphtha boiling range feedstock in the presence of a first volume of hydrodesulfurization catalyst. One effective condition includes a first start catalyst bed temperature and a first space velocity. The naphtha boiling range feed can then be contacted with an arsenic scavenging catalyst. This may be followed by contacting the naphtha boiling range feed with a second volume of hydrodesulfurization catalyst that is no more than about 95% of the first volume under a second effective hydrodesulfurization condition. This second effective selective hydrodesulfurization condition can include (i) a second start catalyst bed temperature that is at least about 1.5 ° C. higher than the first start catalyst bed temperature and (ii) the first Includes a second space velocity that is faster than the space velocity. In this aspect of the invention, the naphtha boiling range feed can be contacted with the arsenic scavenging catalyst prior to contact with the second volume of hydrodesulfurization catalyst. Contacting the naphtha boiling range feed with the arsenic scavenging catalyst and the second volume of hydrodesulfurization catalyst results in the specified continuous while maintaining the specified product sulfur content in the hydrodesulfurized naphtha feed. It can be continued for hours of operation.

FIG. 1 schematically shows an example of a reactor suitable for carrying out embodiments of the present invention.

  In certain embodiments, a low cost method is provided that produces a naphtha boiling range product having at least an equivalent, preferably improved octane number, while achieving the desired process continuous run time. This improved octane number storage can be achieved by using a combination of full charge of As capture catalyst compatible with the desired continuous run time and reduced hydrodesulfurization catalyst charge. This can allow the hydrodesulfurization reactor to be operated at a higher initial temperature, which can enhance octane number storage during the initial part of the continuous operation time of the hydrodesulfurization process. .

  In a selective hydrodesulfurization process, various considerations can be balanced to select the size (or amount) of catalyst charge and the processing temperature. It may often be desirable to remove sulfur to a level that corresponds to the current requirements for low sulfur fuels. For example, the production of naphtha products containing about 15 ppm by weight or less, such as about 10 ppm by weight or less, is often desirable. Another consideration may include maintaining the activity of the catalyst. Typically, the catalyst should deactivate more rapidly during higher temperature operation. Thus, lower operating temperatures may be preferred, particularly during the initial processing period after new catalyst is added to the hydroprocessing reactor. Yet another consideration may include the preservation of olefins in the resulting naphtha product. Often, treatment of the feedstock at a temperature higher than necessary to meet the desired sulfur specification can result in further saturation of the olefin. This consideration tends to suggest that lower reaction temperatures are preferred to avoid overtreatment of the feedstock. However, the selectivity of the catalyst can increase with increasing temperature. Here, selectivity refers to the relative activity for hydrodesulfurization relative to the activity for olefin saturation. Thus, there are factors that can favor both lower and higher temperature processing.

  Contaminants in the raw material can provide another set of issues for consideration. A catalyst poison such as arsenic can reduce the activity of the hydrodesulfurization catalyst during the course of the hydrodesulfurization process. Arsenic can often deactivate the catalyst at a much faster rate than would normally be expected. One way to counteract this deactivation involves increasing the overall catalyst loading. For practical considerations, an end-of-run temperature above about 800 ° F. (about 427 ° C.) is usually not preferred, and preferably the end-of-run temperature may be less than about 675 ° F. (about 357 ° C.). Increasing the amount of hydrodesulfurization catalyst can lower the temperature required to effectively hydrodesulfurize a given flow rate of naphtha feed. By increasing the amount of hydrodesulfurization catalyst, a portion of the catalyst may be deactivated while still allowing the catalyst of sufficiently higher activity to remain below the desired temperature during the desired continuous run time.

  Traditionally, increased catalyst loading has been used in conjunction with arsenic capture catalysts. The arsenic scavenging catalyst can be packed into the catalyst bed so that the feed comes into contact with the arsenic scavenging catalyst prior to contact with the hydrodesulfurization catalyst in the reactor. Without wishing to be bound by theory, the hydrodesulfurization catalyst only undergoes normal deactivation from the process and does not undergo more rapid deactivation due to the presence of arsenic, so the hydrodesulfurization catalyst binds to arsenic. Therefore, it is considered that the amount of arsenic reaching the hydrodesulfurization catalyst is decreased and the continuous operation time of the reactor is extended.

  In contrast to the conventional use of arsenic scavenging catalysts, various embodiments of the present invention use arsenic scavenging catalysts to maintain and preferably increase the octane number of the desulfurized naphtha product. This can be achieved by reducing the amount of hydrodesulfurization catalyst used. By using less catalyst, the start-up temperature for the reaction can be increased, which can allow greater retention. In certain embodiments, the use of an arsenic scavenging catalyst reduces the volume of the hydrodesulfurization catalyst to no more than about 95%, such as no more than about 90% or no more than about 85% of the volume required without the arsenic scavenging catalyst. Can make it possible. By reducing the volume of the hydrodesulfurization catalyst, the corresponding space velocity of the raw material in contact with the hydrodesulfurization catalyst can be increased while still processing a similar flow rate of the raw material. In certain embodiments, the use of an arsenic capture catalyst may allow a space velocity greater than the space velocity without the use of an arsenic capture catalyst. Preferably, the space velocity with the arsenic scavenging catalyst may be at least about 105% of the space velocity without the arsenic scavenging catalyst, such as at least about 110% of the space velocity without the arsenic scavenging catalyst.

Feedstock In various embodiments, the feedstock for the selective hydrodesulfurization process can be a naphtha boiling range feed, particularly an olefinic naphtha boiling range feed. Suitable feedstocks can typically boil in the range of about 50 ° F. (about 10 ° C.) to about 450 ° F. (about 232 ° C.). With regard to olefin content, suitable feedstocks may advantageously comprise feedstocks having an olefin content of at least about 5% by weight. Non-limiting examples of such suitable feedstocks include, but are in no way limited to, fluid catalytic cracker naphtha (FCC catalytic naphtha or catalytic cracking naphtha), steam cracking naphtha, coker naphtha, or their Combinations can be included. Blends of olefinic and non-olefinic naphthas are also included as long as the blend has an olefin content of at least about 5% by weight.

  Olefinic naphtha refinery streams generally contain not only paraffins, naphthenes, and aromatics, but also unsaturateds such as open and cyclic olefins, dienes, and cyclic hydrocarbons having olefin side chains. The olefinic naphtha feedstock may have a total olefin concentration of about 60 wt% or less, such as about 50 wt% or less, or about 40 wt% or less. Additionally or alternatively, the olefin concentration can be at least about 5 wt%, such as at least about 10 wt% or at least about 20 wt%. The olefinic naphtha feedstock may also have a diene concentration of up to 15 wt%, but more typically less than about 5 wt%, based on the total weight of the feedstock. High diene concentrations are usually undesirable because they can result in gasoline products with poor stability and hue.

  The sulfur content of the olefinic naphtha can be at least 100 ppm by weight, such as at least about 500 ppm by weight, at least 1000 ppm by weight, or at least about 1500 ppm by weight. Additionally or alternatively, the sulfur content can be about 7000 ppm by weight or less, such as about 6000 ppm by weight, about 5000 ppm by weight, or about 3000 ppm by weight. Sulfur is typically present as organically bound sulfur, i.e., sulfur compounds such as simple aliphatic mercaptans, naphthenic mercaptans, and aromatic mercaptans, sulfides, disulfides and polysulfides. obtain. Other organically bound sulfur compounds may include a class of heterocyclic sulfur compounds such as thiophene and higher homologues / analogues thereof including dibenzodithiophene and the like.

  Nitrogen can also be present in the feed. In certain embodiments, the amount of nitrogen can be at least about 5 ppm by weight, such as at least about 10 ppm by weight, at least about 20 ppm by weight, or at least about 40 ppm by weight. Additionally or alternatively, the nitrogen content can be about 250 ppm by weight or less, such as about 150 ppm by weight or less, about 100 ppm by weight or less, or about 50 ppm by weight or less.

  Arsenic may also be present in the raw material. In certain embodiments, the amount of arsenic can be at least about 1 weight ppb, such as at least about 5 weight ppb, at least about 10 weight ppb, at least about 20 weight ppb, or at least about 40 weight ppb. Additionally or alternatively, the arsenic content can be about 100 weight ppb or less, such as about 75 weight ppb or less, or about 50 weight ppb or less.

Catalyst selective hydrodesulfurization is carried out by exposing the olefinic naphtha feed to one or more beds of hydrodesulfurization catalyst under effective selective hydrodesulfurization conditions. In certain embodiments, the arsenic capture catalyst can be used in a separate bed, for example, a bed upstream of the hydrodesulfurization catalyst bed, or the arsenic capture catalyst is in the upper portion of the bed that also includes the hydrodesulfurization catalyst. It can also be filled.

  Typically, arsenic scavenging catalysts have sufficient ability to sequester (adsorb) arsenic, but otherwise have a reduced or minimal impact on the desired reaction, eg, hydrodesulfurization The catalyst has a low catalytic activity. A typical arsenic scavenging catalyst may be a relatively low activity supported nickel-based catalyst. For example, the catalyst may comprise about 5 wt% to about 20 wt% Ni on an alumina support. Commercial examples of such arsenic scavenging catalysts include TK-47 commercially available from Haldor Topsoe.

  In certain embodiments, the amount of arsenic scavenging catalyst included in the catalyst bed may depend on the amount of arsenic present in the feed and the desired continuous operation time. Preferably, the amount of arsenic scavenging catalyst may be sufficient to prevent substantial arsenic contact with the hydrodesulfurization catalyst. Having an excess of arsenic scavenging catalyst has an impact on hydrodesulfurization activity and / or selectivity as arsenic scavenging catalysts typically may have relatively low activity against hydrodesulfurization and / or olefin saturation. Note that there may be little or no (other than increased catalyst cost).

  In various embodiments, suitable selective hydrodesulfurization catalysts include at least one Group VIII metal oxide such as Co and / or on a support material such as silica, alumina, or combinations thereof. A catalyst composed of an oxide of Ni (preferably containing at least Co); and at least one Group VIB metal oxide, such as an oxide of Mo and / or W (preferably containing at least Mo) Can be included. Other suitable hydrotreating catalysts can include zeolite catalysts and noble metal catalysts (eg, where the noble metal includes Pd and / or Pt). It is within the scope of the present invention that two or more types of hydroprocessing catalysts are used in the same reaction vessel. The Group VIII metal oxide of the selective hydrodesulfurization catalyst may be present in an amount ranging from about 0.1% to about 20%, preferably from about 1% to about 12%. Additionally or alternatively, the Group VIB metal oxide may be present in an amount ranging from about 1% to about 50%, preferably from about 2% to about 20%. All metal oxide weight percents are based on the support. By “on carrier” the percentage is based on the weight of the carrier. For example, if the support weighs 100 grams, 20 wt% Group VIII metal oxide means that 20 grams of Group VIII metal oxide is on the support.

  The hydrodesulfurization catalyst used in the practice of the present invention may preferably be a supported catalyst. Any suitable refractory (or flame retardant) catalyst support material, preferably an inorganic oxide support material, can be used as the support for the catalyst of the present invention. Non-limiting examples of suitable support materials include zeolite, alumina, silica, titania, calcium oxide, strontium oxide, barium oxide, carbon, zirconia, magnesia, diatomaceous earth, lanthanide oxides (cerium oxide, lanthanum oxide, nedium oxide , Yttrium oxide, and praseodymium oxide), chromia, thorium oxide, urania, niobia, tantala, titanium oxide, zinc oxide, aluminum phosphate, and the like, and combinations thereof. Preferred supports include alumina, silica, and silica-alumina. It should be understood that the support material can also include small amounts of contaminants, such as Fe, sulfate, silica, and / or various metal oxides that can be introduced during the preparation of the support material. These contaminants can often be present in the raw materials used to prepare the support and are preferably present in an amount of less than about 1% by weight, based on the total weight of the support. The carrier material is substantially free of such contaminants (eg, about 0.1 wt% or less, preferably about 0.05 wt% or less, about 0.01 wt% or less, or an undetectable amount) Is more preferable. Additionally or alternatively, from about 0% to about 5%, such as from about 0.5% to about 4%, or from about 1% to about 3% by weight of additive in the carrier and / or carrier The additive can be present above and can be selected from the group consisting of phosphorus and metals or metal oxides from Group IA (alkali metals) of the Periodic Table of Elements (CAS version).

Reaction Conditions and Environment Selective hydrodesulfurization can be any suitable reaction system, eg, one or more fixed beds, each of which can comprise one or more catalyst beds of the same or different hydrodesulfurization catalysts. It can be carried out in a reactor. Optionally, more than one type of catalyst can be used in a single bed. Other types of catalyst beds can be used, but a fixed bed is preferred. Non-limiting examples of such other types of catalyst beds that can be used in the practice of the present invention include, but are not limited to, fluidized beds, ebullated beds, slurry beds, moving beds, and the like, and their Combinations can be included. Interstage cooling between reactors or between catalyst beds in the same reactor can be used in some embodiments, because some olefin saturation can occur and olefin saturation as well as desulfurization. Is generally exothermic. Some of the heat generated during hydrodesulfurization can be recovered, for example, by conventional techniques. If this heat recovery option is not available, conventional cooling may be performed by a cooling facility such as cooling water or air and / or using a hydrogen quench stream. In this way, the optimal reaction temperature can be more easily maintained.

  Generally, the selective hydrodesulfurization conditions are about 425 ° F. (about 218 ° C.) to about 800 ° F. (about 427 ° C.), preferably about 500 ° F. (about 260 ° C.) to about 675 ° F. (about 357 ° C.). ) Temperature. In certain embodiments, the temperature at the start of the reaction run is at least about 450 ° F. (about 232 ° C.), such as at least about 475 ° F. (about 246 ° C.), at least about 500 ° F. (about 260 ° C.), or at least It may be about 510 ° F. (about 266 ° C.). Additionally or alternatively, the temperature at the start of operation can be about 575 ° F. (about 302 ° C.) or less, such as 540 ° F. (about 282 ° C.) or less, or about 525 ° F. (about 274 ° C.) or less.

  Independently or in combination with embodiments describing the starting temperature, the temperature at the end of the processing run is about 800 ° F. (about 427 ° C.) or less, eg, about 750 ° F. (about 399 ° C.) or less, about It can be 700 ° F (about 371 ° C) or less, about 675 ° F (about 357 ° C) or less, or about 650 ° F (about 343 ° C) or less. Additionally or alternatively, the temperature at the end of the processing run is at least about 550 ° F. (about 288 ° C.), such as at least about 575 ° F. (about 302 ° C.), at least about 600 ° F. (about 316 ° C.), or It can be at least about 625 ° F. (about 329 ° C.).

  In various embodiments, the temperature selected as the end of the processing run may depend on various factors. For example, it may be desirable to operate the reactor and other equipment in the reaction system at temperatures below a certain value. This may be due to equipment limitations, the desired temperature in another upstream or downstream process, or for other reasons. Another consideration may be the rate of catalyst deactivation. As the catalyst deactivates, the number of remaining active sites on the catalyst can decrease. If many of the active sites on the catalyst are deactivated, the process stability using the catalyst can be reduced. This can be reflected, for example, in the need to increase the temperature at a faster rate in order to maintain a substantially constant sulfur level. Furthermore, as mentioned above, some types of catalysts generally deactivate more rapidly at higher temperatures.

  In certain embodiments, the temperature difference between the start of the hydrodesulfurization process and the end of the process is at least about 25 ° F. (eg, about 14 ° C.), such as at least about 50 ° F. (about 28 ° C.), at least about 75 °. F (about 42 ° C.), or at least about 100 ° F. (about 56 ° C.). Additionally or alternatively, the temperature difference between the start and end of operation can be about 300 ° F. (about 167 ° C.) or less, eg, about 200 ° F. (about 111 ° C.) or less, about 150 ° F. (about 83 ° C.). ), About 100 ° F. (about 56 ° C.) or less, or about 75 ° F. (about 42 ° C.) or less.

Other selective hydrodesulfurization conditions are about 60 psig (about 400 kPag) to about 800 psig (about 5.5 MPag), such as about 200 psig (about 1.4 MPag) to about 500 psig (about 3.4 MPag) or about 250 psig (about 1.7 MPag) to about 400 psig (about 2.8 MPag). Hydrogen feed rate is about 500scf / b (about 84Nm ³ / ^{m 3)} to about 6000scf / b (about 1000Nm ³ / ^{m 3),} for example, from about 1000 SCF / b (about 170Nm ³ / ^{m 3)} to about the 3000scf / b (About 510 Nm ³ / m ³ ). Liquid hourly space velocity may be from about 0.5 hr ^-1 (or time ^-1) to about 15hr ^-1, for example, from about 0.5 hr ^-1 to about 10 hr ^-1, or about ^{1hr -1} to about ^{5 hr -1.}

FIG. 1 schematically shows an example of a reactor suitable for carrying out embodiments of the present invention. In FIG. 1, an arsenic-containing naphtha raw material 105 and a hydrogen raw material 107 are introduced into a reactor 110. Reactor 110 is shown as including a separate arsenic capture catalyst bed 112 and a separate hydrodesulfurization catalyst bed 114. Alternatively, the arsenic capture catalyst and hydrodesulfurization catalyst can be in a single bed, with the arsenic capture catalyst packed at the top of the bed. Optionally, an additional hydrodesulfurization catalyst bed 114 can also be included. After treatment in reactor 110, hydrodesulfurization feed 115 can be sent to separator 120. In the embodiment shown in FIG. 1, the separator 120 can advantageously remove a stream 127 containing H ₂ , H ₂ S, and other gas phase products from the remainder of the separate desulfurized naphtha feed 125. .

Product Characterization and Control of Reaction Conditions In various embodiments, hydrotreated naphtha has reduced octane loss compared to hydrotreated naphtha formed from a similar process that does not use an arsenic scavenging catalyst. Or preferably it can be produced without any. Olefin saturation can be reduced by allowing the use of a reduced amount of catalyst and thus increasing the start-up temperature. This may result in higher running octane number (RON) and / or motor octane number (MON) for the resulting hydrotreated naphtha.

  In various embodiments, the goal of the selective hydrodesulfurization process can be to produce a naphtha product having a substantially constant level of sulfur. In certain embodiments, the substantially constant level of sulfur can be at least about 5 ppm by weight, such as at least about 10 ppm by weight, at least about 15 ppm by weight, at least about 20 ppm by weight, or at least about 30 ppm by weight. . Additionally or alternatively, the substantially constant level of sulfur can be about 150 ppm by weight or less, such as about 100 ppm by weight, about 75 ppm by weight, about 50 ppm by weight, or about 30 ppm by weight or less. . As used herein, maintaining a substantially constant level of sulfur in the hydrodesulfurization product can result in a sulfur content within about 5 ppm by weight of the target level (eg, within about 3 ppm by weight). ) Can be defined as maintaining.

  For various reasons, it may be desirable to maintain a substantially constant level of sulfur in the naphtha product. Maintaining a constant level of sulfur may allow process control because gasoline formulators can rely on naphtha product specifications. For this purpose, maintaining a substantially constant sulfur level can be beneficial because the sulfur content does not increase. It may also be desirable to provide a constant sulfur level to prevent the sulfur level from being too low. At the product sulfur levels described for embodiments of the present invention, further sulfur removal may indicate that the reaction conditions may be too severe. The use of more severe hydrodesulfurization conditions can sometimes lead to increased olefin bond saturation, which may be undesirable. Thus, achieving the sulfur level below the target level is actually in some cases because the treatment used to achieve the lower sulfur level can still further reduce the RON and / or MON of the naphtha product. Can be harmful.

  In various embodiments, another goal may be to provide a naphtha product with improved octane number. By operating at a higher starting temperature, but with a reduced amount of catalyst (eg, so that the feed is not over-treated), less olefinic bonds can be saturated in the feed and / or converted to mercaptans. Such olefin storage can lead to a reduction in octane loss during hydrodesulfurization. In certain embodiments, octane loss due to hydrodesulfurization may be reduced by about 0.05 RON or more, for example, about 0.1 RON or more, compared to octane loss due to hydrodesulfurization under similar conditions without an arsenic scavenging catalyst. .

  One or both of the above goals can be achieved by the present invention, or none of those goals can be achieved.

  One way to maintain the desired sulfur level may be to use a product sulfur level that provides feedback to the process conditions. Various methods are available for detecting product sulfur levels. One option to monitor sulfur levels may be to collect a sample of hydrodesulfurized naphtha and analyze the sample for sulfur. Because of the time scale associated with catalyst deactivation during processing, off-line analysis of naphtha samples may be sufficient to allow to maintain a substantially constant level. Alternatively, techniques for in-line monitoring of the sulfur content level in the hydrodesulfurized naphtha product can also be utilized. While it may be desirable to use a system with an arsenic scavenging catalyst to reduce product sulfur content under certain circumstances, in other situations a substantially constant level of product sulfur may be maintained Thus, feedback based on the sulfur content in the naphtha product can be used to adjust the reaction conditions. In various embodiments, adjusting the reaction conditions may include, among other things, adjusting the temperature of the catalyst bed (weighted average (or weight average) bed temperature).

Example-Simulation of selective hydrotreating with and without arsenic capture To demonstrate the benefits of using an arsenic capture catalyst, a process simulation for a selective hydrodesulfurization process was constructed. The simulation results are shown in Table 1. The conditions for these simulations included: about 5500 barrels / day (about 870 m ³ / day) FCC naphtha feed; about 4200 wt ppm feed sulfur content; about 45 centimeters / 1 Gram raw bromine number; and raw arsenic content of about 40 ppb. One purpose of the process was to reduce the sulfur content to at least 120 ppm by weight while meeting approximately 6 years of continuous operation time. The process gas rate was about 620000 scf / hr (about 18000 Nm ³ / hr) with about 72% hydrogen and about 10 ppm by weight CO (the rest being an inert gas). The simulated catalyst corresponded to a commercial CoMo catalyst on a refractory support.

The first data string in Table 1 (without arsenic capture) indicates that a catalyst volume of about 2043 ft ³ (about 57.9 m ³ ) was required to meet the goal of continuous run time of nearly 6 years. . The expected start of run (SOR) temperature was about 502 ° F. (about 261 ° C.). The second data string shows that by adding about 71.5 ft ³ (about 2.0 m ³ ) of arsenic scavenging catalyst, the same continuous running time is at a lower catalyst volume of about 1716 ft ³ (about 48.6 m ³ ) While it could be achieved, it shows that the octane loss was reduced by about 0.12 RON (running octane number). The higher SOR temperature in the second case of 508 ° F. (about 264 ° C.) appeared to reduce mercaptan formation and improve octane loss. Higher SOR temperatures usually result in faster deactivation, but this is offset by the presence of an arsenic scavenging catalyst, reducing arsenic-based deactivation. It is noted that the amount of arsenic capture catalyst in the second data row was approximately equal to the amount required to minimize arsenic reaching the main catalyst bed. This was indicated by an expected arsenic capture continuous operation time of about 6.1 years.

Some embodiments of the present invention are shown below.
1.
A method of selectively hydrotreating a naphtha boiling range raw material,
Supplying a naphtha boiling range feedstock containing at least about 5 wt% olefin and at least about 1 ppb arsenic;
Identifying continuous operation time and product sulfur content for a selective hydrodesulfurization process;
Determining a first effective selective hydrodesulfurization condition for selectively hydrodesulfurizing the naphtha boiling range feedstock in the presence of a first volume of hydrodesulfurization catalyst, wherein Effective conditions include a first start catalyst bed temperature and a first space velocity;
Contacting the naphtha boiling range feedstock with an arsenic capture catalyst; and
Contacting the naphtha boiling range feedstock with a second volume of hydrodesulfurization catalyst that is less than about 95% of the first volume under a second effective hydrodesulfurization condition, comprising: The second effective selective hydrodesulfurization condition includes a second start catalyst bed temperature that is at least about 1.5 ° C. higher than the first start catalyst bed temperature, and a second greater than a first space velocity. Including a space velocity;
Including
The naphtha boiling range feed comes into contact with the arsenic capture catalyst prior to contact with the second volume hydrodesulfurization catalyst, and further the naphtha boiling range feed, the arsenic capture catalyst, and the second volume hydrodesulfurization. The method wherein contact with the catalyst is continued for the specified continuous operating time while maintaining the specified product sulfur content in the hydrodesulfurized naphtha feed.
2.
The method of claim 1, wherein the second volume of catalyst is about 90% or less of the first volume.
3.
The method of claim 1 or 2, wherein the second space velocity is about 105% of the first space velocity.
4).
4. The method of any one of claims 1 to 3, wherein the second start catalyst bed temperature is at least about 2.5 ° C. higher than the first start catalyst bed temperature.
5.
5. The method of any one of 1 to 4 above, wherein the identified product sulfur content is less than about 150 ppm by weight.
6).
6. A method according to any of 1 to 5 above, wherein the identified product sulfur content is from about 10 ppm to about 30 ppm by weight.
7).
7. The method of any one of 1 to 6 above, wherein the starting catalyst bed temperature is from about 450 ° F. (about 232 ° C.) to about 575 ° F. (about 302 ° C.).
8).
8. The method according to any one of 1 to 7 above, wherein the weighted average bed temperature at the end of the contact of the hydrodesulfurization catalyst is about 550 ° F. (about 288 ° C.) to 750 ° F. (about 399 ° C.).
9.
The second effective selective hydrodesulfurization conditions include a pressure of about 60 psig (about 400 kPag) to about 800 psig (about 5.5 MPag), about 500 standard cubic feet per barrel (scf / b) (about 84 Nm ³ / M ³ ) to about 6000 scf / b (about 1000 Nm ³ / m ³ ) hydrogen feed rate and liquid space velocity from about 0.5 hr ⁻¹ to about 15 hr ^−1. the method of.
10.
The second effective selective hydrodesulfurization conditions include a pressure of about 200 psig (about 1.4 MPag) to about 500 psig (about 3.4 MPag), about 1000 scf / b (about 170 Nm ³ / m ³ ) to about 3000 scf / b (approximately 510Nm ³ / ^{m 3)} hydrogen feed rate, and from about 0.5 hr ^-1 liquid hourly space velocity of about 10 hr ^-1, a method according to any one of the above 1 9.
11.
Contact of the naphtha feed with the second volume of hydrodesulfurization catalyst under the second effective hydrodesulfurization conditions comprises the naphtha feed and the first volume of hydrodesulfurization catalyst. 11. A process according to any of the preceding claims, which results in an octane loss of at least 0.05 RON less than the corresponding octane loss due to contact under the first effective hydrodesulfurization condition.
12
12. A method according to any of 1 to 11 above, wherein the naphtha boiling range feedstock comprises at least about 10 ppb arsenic, preferably at least about 20 ppb arsenic.

Claims (8)

A method of selectively hydrotreating a naphtha boiling range raw material,
Supplying a naphtha boiling range feed containing at least 5 wt% olefin and at least 1 ppb arsenic;
Identifying continuous operation time and product sulfur content for a selective hydrodesulfurization process;
Determining a first effective selective hydrodesulfurization condition for selectively hydrodesulfurizing the naphtha boiling range feedstock in the presence of a first volume of hydrodesulfurization catalyst, wherein The effective condition of is a process comprising a first start catalyst bed temperature and a first space velocity ,
The effective selective hydrodesulfurization conditions are: 60 psig (400 kPag) to 800 psig (5.5 MPag) pressure, 500 scf / b (84 Nm ³ / m ³ ) to 6000 scf / b (1000 Nm ³ / m ³ ) hydrogen feed rate. And including a liquid space velocity at 0.5 hr ⁻¹ to 15 hr ⁻¹ ;
Contacting the naphtha boiling range feed with an arsenic scavenging catalyst; and a second effective selective hydrofluoric desulfurization catalyst with a second volume of the naphtha boiling range feed that is 95 % or less of the first volume. Contacting under hydrodesulfurization conditions, wherein the second effective selective hydrodesulfurization condition is a second start catalyst bed that is at least 1.5 ° C. higher than the first start catalyst bed temperature. a step including temperature, and the first space velocity greater than the second space velocity,
The second effective selective hydrodesulfurization conditions are 60 psig (400 kPag) to 800 psig (5.5 MPag) pressure, 500 standard cubic feet per barrel (scf / b) (84 Nm ³ / m ³ ) to 6000 scf / a hydrogen feed rate of b ( 1000 Nm ³ / m ³ ) and a liquid space velocity of 0.5 hr ⁻¹ to 15 hr ⁻¹ ,
The starting catalyst bed temperature is 450 ° F. (232 ° C.) to 575 ° F. (302 ° C.);
A step wherein the weighted average bed temperature at the end of contacting the hydrodesulfurization catalyst is from 550 ° F. (288 ° C.) to 750 ° F. (about 399 ° C.) ;
Including
The naphtha boiling range feed comes into contact with the arsenic capture catalyst prior to contact with the second volume hydrodesulfurization catalyst, and further the naphtha boiling range feed, the arsenic capture catalyst, and the second volume hydrodesulfurization. Contact with the catalyst is continued for the specified continuous operating time while maintaining the specified product sulfur content in the hydrodesulfurized naphtha feed ,
Contact of the naphtha feed with the second volume of hydrodesulfurization catalyst under the second effective hydrodesulfurization conditions comprises the naphtha feed and the first volume of hydrodesulfurization catalyst. A process that results in an octane loss of at least 0.05 RON less than the corresponding octane loss due to contact under said first effective hydrodesulfurization conditions . The method of claim 1, wherein the second volume of catalyst is 90 % or less of the first volume. 3. A method according to claim 1 or 2, wherein the second space velocity is 105 % of the first space velocity. The method according to any of claims 1 to 3, wherein the second start-up catalyst bed temperature is at least 2.5 ° C higher than the first start-up catalyst bed temperature. The method according to any of claims 1 to 4, wherein the specified product sulfur content is less than 150 ppm by weight. 6. A method according to any one of claims 1 to 5, wherein the identified product sulfur content is from 10 ppm to 30 ppm by weight. The second effective selective hydrodesulfurization conditions include pressures of 200 psig ( 1.4 MPag) to 500 psig ( 3.4 MPag), 1000 scf / b ( 170 Nm ³ / m ³ ) to 3000 scf / hydrogen feed rate of ^{b (510 Nm 3 / m 3} ), and a liquid hourly space velocity of 0.5 hr ^-1 from 10 hr ^-1, a method according to any one of claims 1 to 6. The naphtha boiling range feedstock comprises at least 10 ppb of arsenic, the method according to any one of claims 1 to 7.

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