JP7241893B2 - Activation of low metal content catalysts - Google Patents

Description

PRIORITY This application claims priority to U.S. Provisional Application No. 62/796,926, filed January 25, 2019, and EP Search Report Application No. 19165756.8, filed March 28, 2019, the disclosures of which are incorporated by reference in their entireties.

Field A method of activating a low metal content catalyst, such as a catalyst containing a low content of precious metals, comprising a first reduction is provided. The present disclosure is useful, for example, in activating low metal content catalysts used in transalkylation and/or isomerization reactions of aromatic hydrocarbons.

BACKGROUND Precious metal-containing catalysts are commonly used for a variety of purposes in refinery and chemical production environments. Applications of noble metal-containing catalysts include hydroprocessing and various processes where saturation of aromatics and/or olefins is desirable.
Transalkylation is an example of a process in which noble metal-containing catalysts are beneficial. During transalkylation, a feed containing a mixture of C9 ₊ aromatics and toluene or benzene can be exposed to a catalyst containing a suitable zeolite framework and supported precious metals. The goal during the transalkylation process is to transfer the methyl group from the C9 ₊ aromatics to toluene or benzene, while the olefins and/or non-aromatics produced by the dealkylation reaction produced by the cracking reaction It is to saturate the olefin. It may be beneficial to reduce or minimize saturation of the aromatic ring during transalkylation.

Many catalysts, such as transalkylation and isomerization catalysts, contain molecular sieves and hydrogenation metals, such as noble metals, as active ingredients. The preparation of the catalyst usually involves making a catalyst precursor comprising a mixture of a molecular sieve and a metal hydride in a high oxidation state. After preparation of the noble metal-containing catalyst precursor, in order for the catalyst precursor to perform its intended catalytic function in the production of the intended product, it is typically charged into a reactor, activated and then subjected to normal operation. need to be in a state. A typical activation procedure includes a reduction step using a hydrogen-containing atmosphere to convert the metal oxide present in the catalyst precursor to a lower oxidation state (e.g., an elemental state with zero valence). can be done. If proper activation does not occur, the catalyst may exhibit less than desired levels of activity or lifetime.
US Pat. No. 9,868,117 describes methods for improving metal-impregnated catalysts, such as catalysts impregnated with noble metals. After loading the catalyst into the reactor, the reactor can be purged of CO in the presence of a hydrogen-containing atmosphere. This can reduce or minimize metal agglomeration while allowing activation of the metal-impregnated catalyst.
There remains a need for improved activation methods for catalyst precursors containing molecular sieves and metal hydrides.

SUMMARY The quality of the reducing hydrogen atmosphere used in the activation step of catalyst precursors containing molecular sieves and metal hydrides has a significant effect on the performance of the activated catalyst, including, but not limited to, its catalytic activity and useful life. I found that I could give In particular, the presence of certain gases, such as carbon monoxide (CO), in a hydrogen atmosphere at high concentrations, such as 10 vppm or more, may cause the catalyst precursor to deplete, for example, ≤0.5 wt%, based on the total mass of the catalyst precursor. , or ≦0.1 wt %, or ≦0.05 wt %, can dramatically affect the activity and/or life of the activated catalyst. First, the catalyst precursor in the reactor, either ex-situ or in-situ, in the presence of a first hydrogen-containing atmosphere containing CO at very low concentrations, e.g., ≤1 vppm. By reducing the body, the reduction catalyst is further activated in situ in the reactor by using a second hydrogen-containing atmosphere having CO at a high concentration, e.g., ≧10 vppm, to form a second hydrogen-containing atmosphere It was found that high-performance twice-activated catalysts could be obtained despite the high CO concentration in the medium.

Various embodiments of the present disclosure provide methods for activating catalysts containing small amounts of hydrogenation metals, such as small amounts of Groups 8-10 noble metals. Prior to loading the low metal catalyst into the reactor, the corresponding catalyst precursor can be activated in a hydrogen-containing atmosphere containing CO up to 1.0 vppm. This can reduce or minimize adverse effects associated with CO exposure prior to the first reduction, such as metal aggregation and/or other catalyst deactivation. After the initial reduction, the catalyst can remain active after exposure to higher levels of CO. Additionally or alternatively, the catalyst can remain active after exposure to an oxygen-containing environment and subsequent additional reduction steps.

1 schematically illustrates typical chemical reactions that may occur during the transalkylation process. The temperatures associated with the first exemplary transalkylation process are shown. Figure 3 shows _C7 , _C9 , and _C10 conversions for the transalkylation process of Figure 2; Figure 2 shows the ethylbenzene conversion for the transalkylation process shown in Figure 2; FIG. 2 shows xylene yields for the transalkylation process of FIG. Figure 2 shows the deethylation conversion for the transalkylation process shown in Figure 2; Temperatures associated with a second exemplary transalkylation process are shown. Figure 8 shows _C7 , _C9 , and _C10 conversions for the transalkylation process of Figure 7; FIG. 7 shows ethylbenzene concentrations for the transalkylation process shown in FIG. 7 shows the deethylation conversion for the transalkylation process shown in FIG. Temperatures associated with a third exemplary transalkylation process are shown. Figure 11 shows _C7 , _C9 , and _C10 conversions for the transalkylation process of Figure 11; FIG. 12 shows the ethylbenzene concentration for the transalkylation process shown in FIG. 11. FIG. FIG. 12 shows the deethylation conversion for the transalkylation process shown in FIG. 11. FIG. Temperatures associated with a fourth exemplary transalkylation process are shown. FIG. 15 shows _C7 , _C9 , and _C10 conversions for the transalkylation process of FIG. FIG. 15 shows ethylbenzene concentrations for the transalkylation process shown in FIG. Figure 15 shows the deethylation conversion for the transalkylation process shown in Figure 15. Average temperatures for three xylene isomerization processes utilizing three different isomerization catalysts activated using different methods are shown. FIG. 20 shows xylene losses for the xylene isomerization process shown in FIG. 19. FIG. FIG. 19 shows ring loss for the xylene isomerization process shown in FIG.

DETAILED DESCRIPTION Overview This disclosure describes a method as including at least one “step”. Each step is to be understood as an action or operation that may be performed once or multiple times in a continuous or discontinuous fashion in the process. Unless stated to the contrary or unless the context clearly dictates otherwise, multiple steps in a process are described as recited, with or without overlap with one or more other steps. It may be done sequentially in order, or optionally in any other order. Additionally, one or more steps or even all steps may be performed simultaneously on the same or different batches of material. For example, in a continuous process, while the first step of the process is being performed on raw materials that have just been fed towards the start of the process, It may be done simultaneously for intermediates resulting from the processing of supplied raw materials. Preferably, the steps are performed in the order listed.

Unless otherwise indicated, all numbers denoting quantities in this disclosure are to be understood as being modified in all instances by the term "about." Also, it should be understood that numerical values used in the specification and claims constitute a specific embodiment. Efforts have been made to ensure the accuracy of the example data. However, it should be understood that any measured data inherently contain some level of error due to limitations in the techniques and equipment used to make the measurements.
As used herein, the indefinite articles "a" or "an" shall mean "at least one," unless stated to the contrary or the context clearly dictates otherwise. Thus, an embodiment using "a metal" may refer to an embodiment using one, two or more metals, unless stated to the contrary or the context clearly indicates that only one metal is used. is included.
As used herein, “vppm” means parts per million by volume, “v%” means percent by volume, “wppm” means parts per million by mass, “wt% ” means percent by weight.
In this disclosure, "catalyst precursor" refers to a catalyst composition that can be subjected to an activation step prior to bringing it into its intended operating conditions to achieve a desired level of intended catalytic function.

As used herein, "molecular sieve" refers to a natural or man-made material with pores of regular structure and/or shape, and "zeolite" refers to tetrahedral atoms linked by bridging oxygen atoms. A type of molecular sieve that has a structured porous framework structure. Examples of known zeolite frameworks can be found in "Atlas of Zeolite Frameworks", 6th revised edition, published on behalf of the "Structure Commission of the International Zeolite Association", Ch. Baerlocher, L.B. McCusker, D.H. Olson, eds., Elsevier, New York (2007) and corresponding website http://www.iza-structure.org/databases/. According to this definition, zeolites can mean not only zeolitic framework types, but also aluminosilicates with crystal structures containing oxides of heteroatoms different from silicon and aluminum. The heteroatom can be any heteroatom generally known to be suitable for inclusion in the zeolitic framework, such as gallium, boron, germanium, phosphorus, zinc, antimony, tin, and/or in the zeolitic framework. Other transition metals that can replace silicon and/or aluminum can be mentioned.

For the purposes of this disclosure, the nomenclature of the elements and their groups used herein follows the Periodic Table used by the International Union of Pure and Applied Chemistry, 1988. An example of the periodic table is shown on the inside front cover page of Advanced Inorganic Chemistry, 6th Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).
In various embodiments, systems and methods are provided for the activation of catalyst precursors containing minor amounts of hydrogenation metals, such as minor amounts of Groups 8-10 noble metals. The amount of metal contained in the catalyst precursor (including, but not limited to, any supports such as, but not limited to, molecular sieves and/or binders) is 0.5 wt% or less (of the catalyst). relative to the total mass), or 0.1 wt% or less, or 0.05 wt% or less. In this disclosure, the concentration of metals in a catalyst precursor or catalyst is defined as the weight percentage of metal relative to the total weight of the catalyst or catalyst precursor, regardless of the oxidation state of the metal and the particular chemical in which the metal is present. Calculated. Therefore, in a catalyst precursor consisting of molecular sieve and _PtO2 , the concentration of metallic Pt is calculated as the mass percentage of elemental Pt with respect to the total mass of the catalyst precursor.

Catalyst precursors containing molecular sieves and metals, such as noble metals, can be made by any traditional method including, but not limited to, incipient wetness impregnation, slurry impregnation, physical blending, and the like. be. In a preferred method, a solid molecular sieve is impregnated with a liquid dispersion, e.g. a solution, preferably an aqueous dispersion, e.g. to obtain a catalyst precursor containing molecular sieves and metals. The metal can be deposited on the outer surface of the molecular sieve particles or deposited on the inner surface thereof in the pores and/or channels in the molecular sieve. Metals can be present in the catalyst precursor in the form of inorganic or organic salts, complexes, oxides, or other forms in any oxidation state. In order for the metal to achieve the desired catalytic function, eg, hydrogenation at the desired level, it is highly desirable for the metal to be distributed on the outer and/or inner surface of the catalyst in a diffuse manner rather than in an aggregated form. For catalysts with low metal loadings, the interspersed distribution of metals in the catalyst is even more important due to the high activity of the metal component.

Prior to loading the catalyst into the reactor, the corresponding catalyst was treated in a hydrogen-containing atmosphere containing ≤ 1.0 vppm CO, or ≤ 0.3 vppm CO, e.g., a hydrogen-containing atmosphere substantially free of CO down to the detection limit. Precursors can be activated. Activation can correspond to exposing the catalyst precursor to a hydrogen-containing atmosphere under conditions suitable to reduce at least a portion of the metals on the catalyst precursor. After activation, the catalyst can then be transferred to and/or loaded into the reactor. Subsequent exposure to CO can temporarily reduce catalytic activity, but removal of CO can restore catalytic activity to baseline. Examples of low loading metal content catalysts include xylene isomerization catalysts and transalkylation catalysts.

One of the difficulties with the use of low metal content catalysts is that they are very vulnerable to deactivation when the corresponding catalyst precursor is reduced in the presence of CO. Without being bound by any particular theory, it is believed that CO can cause agglomeration of metal particles. Furthermore, it is believed that CO may cause further deactivation by other mechanisms. For conventional catalysts with metal contents above 1.0 wt%, the exposure to CO has minimal effect on reactivity. However, activity loss is more pronounced for low metal content catalysts, such as catalysts with metal contents of 0.5 wt% or less, or 0.1 wt% or less, or 0.05 wt% or less.
Because of the potential for substantial activity loss when low metal content catalyst precursors are reduced in the presence of CO, various initiation procedures are used to avoid such activity loss, such as those described in US Pat. No. 9,868,117. is being developed. While such procedures are effective, they require reduction of low metal content catalysts in a substantially CO-free, hydrogen-containing environment. Unfortunately, hydrogen sources available in refineries generally have CO contents of about 10 vppm or higher. Therefore, performing a procedure such as that described in US Pat. No. 9,868,117 may require incorporating unique sources of high purity hydrogen that are not readily available.

It has been found that the need to bring high purity hydrogen into a refinery or chemical plant environment can instead be avoided by reducing the low metal content catalyst precursor prior to transportation of the catalyst and/or loading of the catalyst into the reactor. rice field. This may allow the initial reduction to be carried out in any convenient reaction vessel, for example in a reaction vessel for which a convenient source of high purity hydrogen is available. It has been found that after the first reduction, the low metal content catalyst can remain active after subsequent reductions following oxygen exposure, even though CO may be present during subsequent steps.
Catalyst activation (i.e., activation of the catalyst precursor corresponding to the catalyst) refers to various procedures that occur after loading the catalyst into the reactor and prior to exposure of the catalyst to a hydrocarbon or hydrocarbonaceous stream. There is Catalyst activation may generally include a heating and/or drying phase to raise the catalyst temperature to a suitable temperature for the next activation phase, which may correspond to reduction of the catalyst. Optionally, the catalyst can be sulfided after the reduction step.
In this disclosure, the term "catalyst" is used to refer not only to sulfurized precious metal-containing catalysts, but also to reduced precious metal-containing catalysts in pre-sulfided/non-sulfided composition states. Prior to being reduced to form a catalyst, hydrogenation metals supported on zeolite supports can be referred to as catalyst precursors.

Activation Conditions and Subsequent Reactor Loading In various embodiments, low metal content is achieved by heating and reduction in the presence of 1.0 vppm or less CO, or an environment containing 0.1 vppm or less CO, such as an environment substantially free of CO. Catalysts can be activated. Reduction can be carried out in the presence of a hydrogen-containing environment, but heating can optionally be carried out in the presence of either a hydrogen-containing environment or an inert gas environment.
The first hydrogen containing atmosphere may correspond to an atmosphere containing 1.0 vol% or more, or 3.0 vol% or more, or 5.0 vol% or more, or 10 vol% or more _H2 , for example up to about 100 vol% hydrogen. The remainder of the hydrogen-containing environment or inert gas environment may correspond to an inert gas such as _N2 or a noble gas (ie Ar, He, Ne). Optionally, _CO2 can be present as long as the CO concentration is 1.0 vppm or less, or 0.3 vppm or less. Preferably, the atmosphere is substantially free of _H2O , for example containing no more than 1000 vppm, or no more than 100 vppm, or no more than 10 vppm of _H2O . Preferably, the atmosphere is substantially free of _O2 , eg containing 1 vppm or less _O2 .

The atmosphere may be static, or a flow corresponding to the composition of the atmosphere may be introduced into the vessel containing the low metal content catalyst during at least a portion of the heating and/or reduction. The pressure during heating and/or reduction can be any convenient pressure, such as a pressure from 0.1 MPa-a to 5.0 MPa-a, or from 0.1 MPa-a to 3.6 MPa-a. A heating step can be used to raise the temperature of the catalyst to a target temperature for reducing the catalyst. The temperature is typically selected based on the metal(s) to be reduced, but may be between 150°C and 500°C, or between 150°C and 420°C, or between 200°C and 400°C, or between 200°C and 360°C. temperature. During reduction, the catalyst can be held at the desired temperature for a period of time in the presence of the hydrogen-containing atmosphere, for example a hold time of 0.5 hours to 10 hours. After reduction, the catalyst can be at least partially cooled in the presence of a hydrogen-containing or inert atmosphere.

After reduction of the metal on the catalyst, the reduced catalyst can optionally be exposed to a third oxygen-containing atmosphere for a period of time. An example of a third atmosphere is air. An atmosphere composed at least partially of air may have an O ₂ concentration of 1.0 vol% to 20 vol%. The reduction catalyst can be exposed to the third atmosphere for a period of time. Exposure durations can correspond to as little as a minute or minutes to weeks, months, or years of exposure duration. Examples of durations of exposure to the third atmosphere are 0.5 hours to 1000 hours, or 0.5 hours to 250 hours. More generally, the exposure time can be any convenient time, from 0.5 hours up to several years or even longer. One reason that the reduced catalyst may be exposed to a third oxygen-containing atmosphere is due to transport from the vessel in which the reduction takes place to the reactor in which the catalyst is loaded to perform a refinery or chemical plant process. do.
After transportation and/or other exposure to the third atmosphere, the reduction catalyst can be loaded into the reactor. The catalyst loaded into the reactor can then be subjected to another reduction step. This reduction step can be similar to the above reduction step except that the second atmosphere for the second reduction step can optionally contain 5.0 vppm or more CO. For example, the second atmosphere can contain CO from 5.0 vppm to 25 vppm, or from 5.0 vppm to 20 vppm.

Low Metal Content Catalysts In this discussion, metal-containing catalysts refer to catalysts comprising one or more hydrogenation metals supported on a support material. Optionally but preferably at least one of the one or more hydride metals may correspond to a Group 8-10 noble metal. Examples of Group 8-10 noble metals suitable for use as hydride metals include Pt, Pd, Ru, Ir, Os, Rh, or combinations thereof. More generally, the one or more hydride metals can include Pt, Pd, Ru, Rh, Ir, Os, Ni, Re, Co, Fe, or combinations thereof. Optionally, the catalyst may contain one or more additional metals outside of Groups 8-10, such as any metal commonly included in xylene isomerization or transalkylation catalysts. Examples of such additional metals may include Sn, Ag, Ga, Cu, Mo, and/or other metals that can form alloys with Pt. In some preferred embodiments, the hydrogenation metal can be Pt. The amount of hydrogenation metal supported on the catalyst can be from 0.001 wt% to 0.5 wt%, or from 0.001 wt% to 0.1 wt%, or from 0.001 wt% to 0.05 wt%.

The catalyst can be prepared without a separate binder or matrix material and/or optionally combined with a separate binder or matrix material prior to use. The binder can withstand the desired service temperature and is abrasion resistant. Binders may be catalytically active or inactive, other zeolites, other inorganic materials such as clays and metal oxides such as alumina, silica, silica-alumina, zirconia, yttria, titania, and Combinations of these may be included. Clays may be kaolins, bentonites and montmorillonites and are commercially available. They may be blended with other materials such as silicates. In addition to silica-alumina, other binary porous matrix materials include materials such as silica-magnesia, silica-thoria, silica-zirconia, silica-beryllia and silica-titania. Ternary materials such as silica-alumina-magnesia, silica-alumina-thoria and silica-alumina-zirconia may also be suitable for use as binders. The zeolite may be combined with the binder in any convenient manner. For example, a bound catalyst can be made by starting with powders of both zeolite and binder, kneading these powders together with added water to form a mixture, and then extruding the mixture to create a bound catalyst of desired size. It is possible. Extrusion aids can also be used to modify the extrusion flow properties of the zeolite and binder mixture.

The amount of zeolite in the carrier with binder may be from about 5 wt% zeolite to about 100 wt% zeolite based on the combined weight of binder and zeolite. For example, the amount of zeolite is from about 30 wt% to about 100 wt%, or from about 30 wt% to about 90 wt%, or from about 30 wt% to about 80 wt%, or from about 30 wt% to about 70 wt%, or from about 50 wt% to about 100 wt%. or about 50 wt% to about 90 wt%, or about 50 wt% to about 80 wt%, or about 50 wt% to about 70 wt%, or about 60 wt% to about 90 wt%, or about 60 wt% to about 80 wt%, or about 60 wt% may be to about 70 wt%.
After combining the zeolite with any optional binder, the zeolite can be extruded to form carrier particles. Alternatively, the carrier particles may be formed in any other convenient manner. After formation of the carrier particles, the carrier particles can be impregnated with the base metal salt using an impregnation solution that also contains a dispersant. Additionally or alternatively, the on-support metal can be introduced onto the support by any other convenient method for forming a supported catalyst. Examples of other types of methods of adding metals to the catalyst precursor include, but are not limited to, solution addition to the extrusion mixture, ion exchange, vapor phase deposition, or any other convenient method. can be done.

Impregnation, such as incipient wetness in solution or impregnation by ion exchange, is a common method often used to introduce metals into catalysts containing supports. During impregnation, the support is exposed to a solution containing a salt of the impregnating metal. There are many variables that can affect the distribution of metal salts during impregnation, including salt concentration, pH of the salt solution, zero charge point of the support material, etc., but are equally important during incipient wetness or ion exchange impregnation. It does not exclude other variables that may be In some cases multiple exposure steps can be performed to achieve the desired metal loading on the catalyst. After impregnating the support with the metal salt, the support can optionally be dried to remove excess water. Drying can be carried out at 80° C. to about 200° C. under any convenient atmosphere, such as air.
Examples of noble metal-containing catalysts comprising one or more noble metals supported on (optionally bound) zeolite supports can be xylene isomerization catalysts and transalkylation catalysts. Suitable types of zeolites for xylene isomerization or transalkylation catalysts can include an intermediate pore zeolite framework. Examples of suitable types of mesoporous zeolite framework structures include MFI (e.g. ZSM-5), MEL (e.g. ZSM-11), MTW, MWW (e.g. MCM-22, MCM-49 and MCM-56). ), and MOR (eg, EMM-34).

Transalkylation Examples - Initiation and Exposure Conditions Transalkylation is the process of converting C9 ₊ aromatics and _C6-7 aromatics (i.e., benzene and/or toluene) to xylenes ( _C8 aromatics). is. This may allow the conversion of two less valuable feedstocks into a product with a higher percentage of more valuable xylenes.
FIG. 1 provides an overview of desirable reactions and undesirable side reactions that can preferably be reduced or minimized during transalkylation. In the example shown in Figure 1, a mixture of C9 ₊ aromatics representing toluene 102 and heavy aromatics reformate 104 represents the input feedstock for the transalkylation. Although 1,3,5-trimethylbenzene and 1-ethyl-4-methylbenzene are shown as examples of components present in the heavy aromatic reformate 104, it is noted that various C9 ₊ compounds may be present. should understand. The desired reactions during the transalkylation process correspond to transalkylation 110, dealkylation 120, and alkene saturation 130. Preferably, ring loss 140 occurs in a small or minimal amount.

To investigate the effect of various initiation and exposure conditions on transalkylation catalysts, samples of catalyst precursors for transalkylation catalysts containing 0.03 wt% Pt supported on alumina-bound zeolite were subjected to four different types of reduction. exposed to conditions. The first set of conditions corresponded to in situ reduction with high purity hydrogen. The second set of conditions corresponded to in situ reduction with a hydrogen stream containing 10 vppm CO. A third set of conditions was chosen to result in a short exposure to an oxygen-containing atmosphere (eg, air) after the ex situ reduction. A fourth set of conditions was chosen for prolonged exposure to air after ex situ reduction. For the third and fourth sets of conditions, the exposure to the oxygen-containing atmosphere was followed by an additional reduction step in an atmosphere containing 10 vppm CO. "In-situ" means inside the reactor where the catalyst is loaded to ultimately carry out its normal intended use. "Ex-situ" means an environment other than within the reactor in which the catalyst is loaded to ultimately perform its normal intended use.

The catalysts reduced using these four procedures were then evaluated for catalytic performance in transalkylation service using typical feedstocks for transalkylation (TA). The transalkylation feed corresponded to a mixture of tailed heavy aromatics reformate (a mixture containing mainly various C9 ₊ aromatics) and toluene. Most of the tests were done with 50 wt% terminal heavy aromatic reformate and 50 wt% toluene.
Catalyst performance was evaluated under the following conditions: weight hourly space velocity (WHSV) of 3 h ^-1 ; reaction pressure of 360 psig; _H2 :hydrocarbon in the feed. a molar ratio of about 2.0; and an inlet temperature of 660°F (about 350°C). For performance evaluation, the reactor was loaded with 30 grams of transalkylation catalyst mixed with 30 grams of inert diluent particles (loaded as a whole extrudate). Transalkylation catalyst samples corresponded to samples exposed to flowing air for 3 hours or 7 days according to the procedures described above.

There are several methods for characterizing catalyst performance during transalkylation reactions. One option is to account for the total conversion of _C7 , _C9 , and _C10 compounds in the feed to other components. A second option is to determine the amount of xylenes produced as a result of the conversion of _C7 , _C9 , and _C10 compounds. Yet another option is to determine the concentration of ethylbenzene in the product. Yet another option is to account for the amount of ethyl side chain removal from the ethylated aromatic ring, which can also be referred to as de-ethylation. For conversion of _C7 , _C9 , and _C10 compounds, a desirable goal may be to achieve 50% or greater conversion. With respect to de-ethylation, a desirable goal may be to have a de-ethylation of 90% or greater. For ethylbenzene content in the product, a desirable goal may be to have 0.4 wt% or less ethylbenzene.
The test data are presented in attached Figures 2-21 and are described below. In these figures, "ToS" means time on stream, "EB" means ethylbenzene, "INLET" means inlet temperature, "AVG" means average temperature, "CONV." means conversion, "DE-C2" means deethylation, "ART" means average reactor temperature, "10 PPM CO" means that the reaction This means that the feed to the vessel contains 10 vppm CO.

Transalkylation Example 1 - Baseline A first set of conditions was designed to represent in situ reduction of the catalyst in the reactor. After loading the catalyst precursor into the reactor, the reactor was pressurized with _H2 to 2.4 MPa-g. H ₂ was then flowed through the reactor at about 20° C. for 3 hours. Since the hydrogen treat gas corresponded to electrolytic hydrogen, the treat gas during the first reduction was substantially free of CO. The reactor temperature was then increased to about 350°C using a heating ramp rate of 40°C/hour. The temperature was maintained at about 350°C for 2 hours. The catalyst was then sulfided by exposure to 400 wppm _H2S in _H2 for 1 hour. The hydrocarbon feedstock was then introduced into the reactor while the sulfide gas flow rate was maintained for 1 hour. The gas source was then switched to 100% _H2 . This initiation procedure was designed to be an in situ initiation of a low metal content catalyst using a specific hydrogen source.

Figures 2-6 detail the reaction conditions and results of conducting the transalkylation process with the catalyst reduced according to the first procedure with electrolytic hydrogen (ie, substantially no CO in the hydrogen stream). indicates The results in FIGS. 2-6 represent baseline results for performing in situ reduction where the low metal content catalyst would not be exposed to oxygen after the reduction process. Figure 2 shows the temperature profile at the inlet of the reactor and the average reactor temperature required to maintain a stable level of conversion of toluene, _C9 , and _C10 compounds in the feed (shown in Figure 3). The target amount of conversion was 52%. As can be seen, the temperature profile of FIG. 2 required to maintain the stable conversion of FIG. 3 was relatively flat. However, on day 7, a temporary increase in temperature was required due to the introduction of 10 vppm of CO into the reaction environment. CO temporarily suppressed the activity of the transalkylation catalyst, but the activity recovered on the 8th day after CO was removed from the reaction environment.

FIG. 4 shows the ethylbenzene concentration in the reaction product. After an initial period of time, the ethylbenzene concentration is also relatively stable at stable temperatures. Again, the amount of ethylbenzene in the product increased during introduction of CO into the hydrogen treat gas on day 7, but returned to lower levels upon removal of CO on day 8.
FIG. 5 shows xylene yields by transalkylation. After an initial period of time, the xylene yield is also relatively constant at constant temperature. Introduction of CO on day 7 may have reduced the xylene yield, but switching back to pure hydrogen on day 8 eliminated any such loss in yield.
Figure 6 shows the amount of deethylation in the product. As shown in Figure 6, removal of the ethyl group from the aromatic ring was stable at stable temperatures, except on day 7 when CO was added to the hydrogen. Similar to the other figures, full deethylation activity returned on day 8. It should be noted that deethylation exceeded 90% with or without the presence of CO in the hydrogen treat gas.

Transalkylation Example 2 - First Reduction with 10 vppm CO (Comparative Example)
The second set of reduction conditions was similar to the first set, but the hydrogen treat gas contained 10 vppm CO at all times during the start-up procedure. This condition was chosen to simulate the use of a hydrogen stream, such as a reformate hydrogen stream, that would be available at a refinery or chemical plant site. After sulfidation, the hydrogen treat gas was switched to 100% hydrogen to allow comparison with baseline start-up procedure activity.
Figures 7-10 provide test data for catalysts reduced according to this Example 2 with a first reduction using a hydrogen treat gas containing 10 vppm CO. FIG. 7 shows the temperature profile that was required to maintain nearly constant conversion of toluene, _C9 aromatics, and _C10 aromatics (shown in FIG. 8). As with the other figures showing reaction temperature profiles, in FIG. 7 solid data points represent inlet temperatures and hollow circles represent average temperatures. Again, the target amount of conversion was about 52%. As shown in FIG. 7, maintaining the approximately 52% conversion of FIG. 8 required an average bed temperature rise of approximately 60° F. (approximately 33° C.) over 5 days. This is in contrast to FIG. 2 where no temperature increase was required over 10 days to maintain the approximately 52% conversion target shown in FIG.

With respect to deethylation, Figure 9 shows that there was significantly less ethyl group removal for the reduced catalyst in the presence of CO. Despite a temperature increase of approximately 40°C during the 5-day test period, the best deethylation achieved was less than 90%. Moreover, during the initial period before the temperature ramp, the deethylation conversion decreased dramatically from about 85% to less than 60%.
Figure 10 shows the ethylbenzene concentration in the product. Based on the relatively low levels of deethylation in Figure 9, it is not surprising that an increase in the amount of ethylbenzene in the product was observed.
The overall results demonstrated by FIGS. 7-10 indicate that the initial reduction of low metal content catalysts in the presence of appreciable concentrations of CO in the atmosphere, even if the atmosphere during the subsequent transalkylation is CO , which results in a catalyst that deactivates over time. In contrast, as shown in FIGS. 2-6, if the initial reduction is performed using a hydrogen-containing treat gas that is substantially free of CO, the low metal content catalyst will be less susceptible to exposure to oxygen, the second reduction step, and remain active after the use of hydrogen-containing gases containing CO during the transalkylation step.

Transalkylation Example 3 - Brief Oxygen Exposure After Reduction A third set of reducing conditions was used to reduce the catalyst in a pilot unit. A third set of reducing conditions included ambient pressure (approximately 0.1 MPa-a) and a hydrogen-containing gas stream corresponding to 100% H ₂ (eg electrolytic hydrogen). The catalyst sample was heated at a ramp rate of 60°F/hour (approximately 33°C/hour) until the temperature reached 350°C. The samples were then held at 350°C for 2 hours. The sample was then cooled to about 20°C while maintaining a 100% _H2 atmosphere.
After this reduction procedure, the catalyst was withdrawn from the pilot unit and exposed to static air for about 3 hours. The catalyst was then subjected to a second reduction step according to the reduction conditions of Example 2 where the hydrogen treat gas contained 10 vppm CO. This was intended to be the concept of performing an ex situ reduction in a first vessel and then transferring the catalyst to the reactor for a second reduction plus optional sulfidation. After sulfiding, the catalyst was then exposed to the feed mixture under transalkylation conditions.

Figures 11-14 show the results of transalkylation. Figure 11 shows the temperature profile used in an effort (Figure 12) to maintain 52% conversion of _C7 , _C9 , and _C10 aromatics. At this level of conversion, Figure 13 shows that after an initial period of 3 days, the catalyst can maintain greater than 90% deethylation at about the same temperature as the reduced catalyst under baseline conditions.
The results in Figure 13 demonstrate several features. First, the activity of the catalyst after the reduction-oxidation-reduction sequence was not identical to that of the catalyst exposed only to reducing conditions before initiation. This suggests some effect on catalytic activity from oxygen exposure. However, initial reduction with high purity hydrogen (before exposure to oxygen) is sufficient to cause the catalyst to maintain desirable activity, even if subsequent reductions are performed with hydrogen containing 10 vppm of CO. was. This is in contrast to the catalyst of Example 2, which was insufficient to reach the desired level of activity for deethylation even at a temperature increase of 33°C (see Figure 9).
Similarly, Figure 14 shows that the catalyst exposed to oxygen for a short period of time during the initial reduction was able to maintain the desired level of activity for the removal of ethylbenzene from the product. This is in contrast to the results in Figure 9 where the ethylbenzene concentration was higher than 0.4 even after increasing the transalkylation temperature.

Transalkylation Example 4 - Long exposure to oxygen after reduction A fourth set of reducing conditions was used in a lab scale reactor. The fourth set of reduction conditions are selected to be the reduction conditions that would be utilized in a commercial setting for ex situ reduction of the catalyst where the catalyst would be reduced ex situ and then transported to the reactor site. bottom. It should be noted that in both Examples 3 and 4, sulfidation is not performed until after oxygen exposure.
The first reduction step under the fourth set of conditions was performed at a pressure of about 0.1 MPa-a. Initial heating of the catalyst precursor samples under the fourth set of conditions was performed in an atmosphere corresponding to 100% _N2 . The catalyst precursor sample was ramped at about 40°C/hour until the temperature reached 275°C. A gas flow corresponding to 4 vol% _H2 in _N2 was then introduced into the reactor for 1 hour while maintaining the temperature at 275°C. The resulting catalyst was then cooled to about 20°C in a 100% _N2 atmosphere. After the reduction procedure, the catalyst was exposed to forced air flow for 7 days.
After exposure to air, the catalyst was sulfided after reduction according to the procedure of Example 3. The catalyst was then exposed to the feed mixture under transalkylation conditions.

Figures 15-18 show the results of transalkylation. FIG. 15 shows the temperature profile used to maintain a relatively stable level of conversion of _C7 , _C9 , and _C10 aromatics. Similar temperatures to Examples 1 and 3 were used, which resulted in 51% conversion of _C7 , _C9 , and _C10 aromatics compared to 52% conversion for the other examples. (Figure 16). Although the _C7 , _C9 , and _C10 aromatic conversions shown in Figure 16 were slightly lower, the catalyst nevertheless had sufficient activity to maintain deethylation above 90% (Figure 18 ). Furthermore, after the initial initiation time, the amount of ethylbenzene in the product was less than 0.4 wt%, achieving the target activity of ethylbenzene removal (Figure 17).
The results in Figures 15-18 demonstrate that the low metal content catalyst can maintain the desired activity even after prolonged exposure to oxygen after the initial reduction.

Xylene Isomerization Catalyst Examples Another type of promising low metal content catalyst is the xylene isomerization catalyst. The industrial xylene isomerization process involves two main reactions, the conversion of ethylbenzene to benzene and ethylene, and the isomerization of a xylene mixture to near-equilibrium xylenes. Another important reaction is the hydrogenation of ethylene to ethene, usually aided by the function of metals on the catalyst. Ethylene is preferably instantaneously converted to ethane because it can alkylate aromatic compounds. Other side reactions include transalkylation, aromatic ring saturation and cracking leading to "xylene loss" and "ring loss".
To investigate the suitability of ex situ reduction procedures for xylene isomerization catalysts, three types of catalyst initiation procedures were utilized. The first procedure (catalyst A) corresponded to exposure to oxygen after ex situ reduction. The second and third procedures (catalysts B and C) were designed to be in-situ reductions with either pure hydrogen treat gas or treat gas containing 10 vppm CO. The xylene isomerization catalyst represented a stacked bed catalyst system containing two catalysts. The upper catalyst layer contained a catalyst containing 0.03 wt% Pt supported on a zeolite support. The lower layer contained a catalyst corresponding to 0.01 wt% Pt supported on a zeolite support.

Catalyst A was subjected to a pre-reduction process to result in ex situ reduction of the low metal content catalyst. Pre-reduction process conditions included a pressure of about 0.1 MPa-a. The catalyst precursor sample was heated at a ramp rate of 90°F/hour (about 50°C/hour) to reach a temperature of about 310°C and then held at 310°C for about 1.5 hours. The resulting catalyst was then cooled to about 20°C. Heating and cooling of the catalyst precursor/catalyst was performed using 100% _N2 as the gas stream, while 12% _H2 and 88% _N2 (substantially A (typically free of CO) treat gas stream was used. The catalyst was then removed from the reactor and exposed to static air for about 4 days.

To test xylene isomerization activity, each catalyst or catalyst precursor (including Catalyst A after pre-reduction) was loaded into a pilot scale reactor and subjected to a start-up procedure. The start-up procedure was initiated by pressurizing the reactor with _H2 to 225 psig (1551 kilopascals, gauge pressure). For Catalyst A and Catalyst C, this pressurization was done with _H2 containing 10 vppm CO, while for Catalyst B 100% _H2 was used. H ₂ was then flowed through the unit at 1.618 SCF per hour at about 20° C. for 1 hour. The reactor temperature was then increased at about 25°C/hour to reach a temperature of 200°C and held at 200°C for about 16 hours. The reactor temperature was then increased at about 25°C/hour to reach a temperature of 360°C and held at 360°C for about 4 hours. The reactor was then cooled to about 338°C. At this point, the xylene isomerization feed was introduced. The inlet temperature was then slowly increased to reach the target level of 75% ethylbenzene conversion. At this point, the hydrotreating gas for Catalyst A and Catalyst C was switched to 100% _H2 to allow comparison of xylene isomerization activity.
The conditions for the xylene isomerization reaction were: WHSV of 12 h ^-1 ; reactor pressure of 225 psig (about 1.6 MPa-g); molar ratio of _H2 to hydrocarbon of 1.0; and reactor inlet temperature of about 350°C. included. The amount of catalyst in the reactor corresponded to about 21 grams of xylene isomerization catalyst, loaded as a whole extrudate mixed with an equal amount of inert diluent.

Figures 19-22 show the results of exposing Catalysts A, B, and C to a xylene isomerization feedstock under isomerization conditions. As noted above, ethylbenzene conversion was maintained at about 75% during the test period shown in Figures 19-22.
Figure 19 shows the average reactor temperature required to maintain 75% ethylbenzene conversion. As shown in FIG. 19, catalyst (“pre-reduction catalyst”) and catalyst B (“base catalyst”) had similar temperature profiles. In contrast, catalyst C (“CO-POISONED catalyst”) required a significant increase in temperature over time to maintain the desired level of conversion. Thus, even though Catalyst A and Catalyst C were exposed to similar reducing conditions including 10 vppm of CO, pre-reduction of Catalyst A with high purity hydrogen allowed Catalyst A to maintain the desired level of activity. bottom.
FIG. 20 shows the amount of xylene lost due to aromatic saturation of xylene. As shown in FIG. 20, catalyst C provided an additional percentage point of xylene loss compared to catalyst A or catalyst B. Similar to FIG. 19, pre-reduction of Catalyst A allowed Catalyst A to maintain desirable performance in avoiding xylene losses even though the in situ reduction step contained 10 vppm of CO.
FIG. 21 shows the amount of ring loss due to cracking of rings into aliphatic chains. FIG. 21 shows that exposure to intermediate oxygen has some effect on activity, as the ring loss for catalyst A is more similar to catalyst C than to catalyst B. However, in this case, Catalyst A and Catalyst C actually have favorable activities compared to Catalyst B to avoid ring loss.

Although this disclosure has been described in terms of particular embodiments, the disclosure is not so limited. Variations/modifications suitable for operation under particular conditions should be apparent to those skilled in the art. It is therefore the intention that the following claims be interpreted as embracing all such variations/modifications as fall within the true spirit/scope of this disclosure.
Next, preferred embodiments of the present invention are shown.
1. A method for activating a catalyst, comprising:
(I) providing a catalyst precursor, said catalyst precursor comprising 0.5 wt% or less of a hydrogenation metal and a molecular sieve, based on the total weight of said catalyst precursor;
(II) in a first vessel, in the presence of a first atmosphere comprising H2 _and 1.0 vppm or less of CO based on the total volume of said first atmosphere; reducing the catalyst precursor to obtain a reduced catalyst; and
(III) transferring the reduction catalyst to a second vessel;
The above method, comprising
2. Further below:
(IV) a second atmosphere comprising at least 1.0 vol _. exposing a portion to obtain an exposed reduction catalyst
1. The method of 1 above, comprising:
3. 3. The method according to 2 above, wherein step (IV) is performed at least partially during step (III).
4. Further below:
(V) in a second container, in the presence of a third atmosphere comprising _H2 and 3.0 vppm or more of CO based on the total volume of said third atmosphere; and treating the reduced catalyst or the exposed reduced catalyst to form a twice reduced catalyst.
4. The method according to any one of 1 to 3 above, comprising
5. 5. The method according to 4 above, wherein the third atmosphere contains 5.0 vppm or more of CO based on the total volume of the third atmosphere.
6. 6. The method according to 4 or 5 above, wherein the third atmosphere contains 10 vol% or more CO based on the total volume of the third atmosphere.
7. 7. The method according to any one of 4 to 6 above, wherein said second atmosphere comprises air.
8. 8. The method of any one of claims 1-7, wherein the first atmosphere comprises at least 99 vol% H ₂ based on the total volume of the first atmosphere.
9. 9. The method of any one of claims 1-8, wherein the third atmosphere comprises at least 99 vol% H ₂ based on the total volume of the third atmosphere.
10. 10. The method of any one of claims 1-9, wherein the catalyst precursor comprises 0.1 wt% or less of hydrogenation metal based on the total weight of the catalyst precursor.
11. 11. The method of any one of claims 1-10, wherein the catalyst precursor comprises 0.05 wt% or less hydrogenation metal, based on the total weight of the catalyst precursor.
12. Further below:
(VI) Sulfiding the twice-reduced catalyst during or after step (V)
12. The method according to any one of 1 to 11 above, comprising
13. 13. The process of any one of claims 1-12, wherein said catalyst comprises a transalkylation catalyst or said catalyst comprises a xylene isomerization catalyst.
14. 14. The method of any one of claims 1-13, wherein the hydride metal comprises at least one Group 8-10 noble metal.
15. 15. The method of any one of claims 1-14, wherein the hydrogenation metal comprises Pt.
16. 16. The method of claim 15, wherein the catalyst precursor further comprises a second metal different from the first metal, the second metal comprising a metal that alloys with Sn, Ga, or Pt, or combinations thereof. the method of.
17. 17. The method of any one of claims 1-16, wherein the hydrogenation metal is at least partially supported on the molecular sieve.
18. 18. The method of any one of claims 1-17, wherein the catalyst precursor further comprises a binder.
19. 19. The method of any one of claims 1-18, wherein said molecular sieve is a zeolite.
20. 20. The method of any one of claims 1-19, wherein the catalyst precursor comprises one or more medium pore zeolites.
21. Step (I) is:
(Ia) providing at least a portion of said molecular sieve, at least a portion of said catalyst precursor, or a combination thereof;
(Ib) combining at least a portion of said molecular sieve, at least a portion of said catalyst precursor, or a combination thereof, with a liquid dispersion of said metal hydride compound to form a molecular sieve-metal mixture, precursor-metal mixture; forming a mixture, or a combination thereof;
(Ic) drying the molecular sieve-metal mixture, the precursor-metal mixture, or a combination thereof; and
(Id) calcining the dry molecular sieve-metal mixture, the dry precursor-metal mixture, or a combination thereof in an oxygen-containing atmosphere;
21. The method according to any one of 1 to 20 above, comprising
22. 22. The method of any one of claims 1-21, wherein the second vessel is a reactor in which the reduced catalyst, the exposed reduced catalyst, or the twice reduced catalyst is used.
23. 23. The method of claim 22, wherein said second vessel is a transalkylation reactor.
24. 24. The method of claim 23, wherein said second vessel is a xylene isomerization reactor.

Claims (9)

A method for activating a catalyst, comprising:
(I) providing a catalyst precursor, said catalyst precursor comprising 0.5 wt% or less of a hydrogenation metal and a molecular sieve, based on the total weight of said catalyst precursor;
(II) in a first vessel, in the presence of a first atmosphere comprising _H2 and 1.0 vppm or less of CO based on the total volume of said first atmosphere; reducing the catalyst precursor to obtain a reduced catalyst ;
(III) transferring the reduction catalyst to a second vessel ; and
(V) in a second container, in the presence of a third atmosphere comprising _H2 and 3.0 vppm or more of CO based on the total volume of said third atmosphere; and treating the reduced catalyst or the exposed reduced catalyst to form a twice reduced catalyst.
The above method, comprising Further below:
(IV) a second atmosphere comprising at least 1.0 _vol . 2. The method of claim 1, comprising exposing a portion to obtain an exposed reduction catalyst. 3. The method of claim 1 or 2 , wherein the third atmosphere comprises 5.0 vppm or more of CO based on the total volume of the third atmosphere. said first atmosphere comprises at least 99 vol% _H2 based on the total volume of said first atmosphere and/or said third atmosphere comprises at least 99 vol based on said total volume of said third atmosphere 4. The method of any one of claims 1-3 , comprising % _H2 . The method of any one of claims 1-4 , wherein the catalyst precursor comprises 0.1 wt% or less hydrogenation metal based on the total weight of the catalyst precursor. Further below:
6. The method of any one of claims 1 to 5 , comprising (VI) sulfiding the twice-reduced catalyst during or after step (V). The method of any one of claims 1-6 , wherein the hydrogenation metal comprises Pt. 8. The method of claim 7 , wherein the catalyst precursor further comprises an additional metal different from the hydrogenation metal, the additional metal comprising a metal that alloys with Sn, Ga, or Pt, or combinations thereof. . 9. The method of any one of claims 1-8 , wherein the second vessel is a reactor in which the reduced catalyst, exposed reduced catalyst, or twice reduced catalyst is used.

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