Stable self-activating catalyst for fixed bed heavy hydrocarbon upgrading

Abstract

A catalyst used for converting a heavy hydrocarbon, wherein the catalyst includes an extrudate having a co-mulled mixture of an inorganic oxide; and at least one metal from Group VIB and at least one metal from Group VIII of the Periodic Table of Elements. An atomic ratio of the at least one metal from Group VIII to the at least one metal from Group VIB is in the range of from 0.0 to 0.3, and the catalyst has a pore structure such that 15 vol.% to 25 vol.% of the total pore volume is present in pores of a diameter greater than 1,000 A and a surface area of that is greater than 150 square meters (m2) / gram (g) and less than 240 m2 / g.

Description

STABLE SELF-ACTIVATING CATALYST FOR FIXED BED HEAVY HYDROCARBON UPGRADINGBACKGROUND OF THE DISCLOSURE

[0001] The present disclosure generally relates to a catalyst useful in hydroprocessing and hydroconversion of heavy hydrocarbon residual feedstocks. More specifically, the present disclosure relates to a self-activating catalyst having a combination of features that include a surface area less than 240 m2 / g, a Ni:Mo ratio of between 0.0 and 0.3, and at least 15 volume % (vol.%) of the TPV in pores having a diameter of greater than 1,000 A.

[0002] The demand for cleaner high value hydrocarbons for use as fuels, lubricants, and base chemicals continues to increase. As crude oil feedstock is becoming heavier and environmental regulations are becoming more stringent, there is a need to develop clean, effective, and efficient solutions for refining heavy cuts including residue oils, also known as bottom of the barrel hydrocarbons, into cleaner and more valuable liquid products. Fixed bed (FB) residue hydroprocessing is used to convert the low-cost residue feedstocks into better-quality crude oil products. The process includes removing components such as sulfur, nitrogen, metals, and microcarbon residue by desulfurization, denitrogenation, and demetallization reactions, and hydrocracking heavy ends to lighter distillate fractions. In this process, heterogeneous catalysts are added to promote the catalytic reactions under conditions of elevated temperature and pressure in the presence of hydrogen. Typical catalysts used for hydroprocessing and hydroconversion of heavy hydrocarbon residue feedstocks contain a Group VIB metal component, such as molybdenum or tungsten, a Group VIII metal component, such as cobalt or nickel, and phosphorus or silicon as dopant, supported on a refractory oxide support.

[0003] There is a need to find catalysts with enhanced catalytic activities and improved stability performance that are suitable for use in hydroprocessing of residue feedstocks. Due to the particular characteristic of heavy hydrocarbon residue, hydroprocessing of such feedstocks using a hydroprocessing catalyst generally results in a decline in its catalytic activity at a rapid rate. Catalysts exhibiting a lower rate of activity decline are considered to have a higher stability. It is desirable to have a catalyst with not only improved initial activity for desulfurization,denitrogenation and demetallization, but also to be highly stable (e.g., maintain improved activity for longer period of time). A catalyst with higher stability will maintain higher conversion than one with lower stability, even though their initial activity difference may be negligible. The catalyst stability is impacted by multiple factors, such as pore structure, metals loading, and the manner in which the catalyst is manufactured.

[0004] U.S. Patent No. 9,114,386, U.S. Patent No. 10,610,854, and U.S. Patent No. 10,220,374 disclose self-activating catalysts found to be useful in hydroprocessing heavy hydrocarbon feedstocks. These catalysts are especially useful in hydrodesulfurization and hydrodemetallization of heavy hydrocarbon feedstocks and their activity increases with use, which is a result of their self-activating property. The catalysts have relatively low concentrations of molybdenum (Mo) and nickel (Ni) with the Ni in proportions that yield a low Ni-to-Mo weight ratio. For example, these catalysts contain from 1 to 10 weight percent (wt %), as metal, Mo and Ni in an amount such that the weight ratio of Ni-to-Mo is less than 0.4 (i.e., atomic ratio is less than 0.66). They are characterized as having between 1 and 10% of their total pore volume (TPV) in pores of diameter greater than 1,000 A, less than 70% of the TPV in pores having a diameter in the range of from 70 A to 150 A, and at least 10% of the TPV in pores having a diameter in the range of from 130 A to 300 A. However, there is no disclosure in any of these patents regarding a catalyst having a macropore structure such that greater than 10% of its TPV is in pores having a diameter greater than 1,000 A.

[0005] While the aforementioned catalysts have desirable hydroprocessing activity, there are continuing efforts to develop new and improved catalyst compositions having increased catalytic activity and / or improved stability. Any improvement in catalytic activity may result in lowering reactor temperatures required for producing clean high value products from heavy hydrocarbon feedstocks such as residue oils compared to the currently required reactor temperatures. By lowering reactor temperatures, the lifespan of catalysts used for refining / upgrading heavy hydrocarbon feedstocks may be extend and provide energy savings.SUMMARY

[0006] In an embodiment, a catalyst used for converting a heavy hydrocarbon includes an extrudate having a co-mulled mixture of an inorganic oxide and at least one metal from Group VIB and at least one metal from Group VIII of the Periodic Table of Elements. An atomic ratio of the at least one metal from Group VIII to the at least one metal from Group VIB is in the range of from 0.0 to 0.3, and the catalyst has a pore structure such that 15 vol.% to 25 vol.% of the total pore volume is present in pores of a diameter greater than l,000A and a surface area of greater than 150 square meters (m2) / gram (g) and less than 240 m2 / g.

[0007] Additional features and advantages of exemplary implementations of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary implementations. The features and advantages of such implementations may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims or may be learned by the practice of such exemplary implementations as set forth hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Advantages of the disclosure may become apparent upon reading the following detailed description and upon reference to the drawings in which:

[0009] FIG. l is a block diagram of a fixed bed reactor system having a reactor loaded with a self-activating catalyst, in accordance with an embodiment of the present disclosure;

[0010] FIG. 2 is a bar graph of the relative hydrodesulfurization (EIDS) activity for the selfactivating and comparative catalysts, in accordance with an embodiment of the present disclosure; and

[0011] FIG. 3 is a bar graph of the relative hydrodemetallization (HDM) activity for the selfactivating and comparative catalysts, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0012] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions will be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0013] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0014] The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount.

[0015] The surface area of the alumina-based material is measured by nitrogen adsorption, using the well-known B.E.T. method. The B.E.T. method of measuring surface area has been described in J. Am. Chem. Soc. 60 (1938) 309-316 which is the method used to measure nitrogen adsorption in the present application.

[0016] The pore size distribution and pore volume of the alumina-based material refers to those properties determined by mercury penetration porosimetry. The measurement of the pore size distribution of the alumina-based material is by any mercury porosimeter suitable for pressure ranges between atmospheric pressure and approximately 412 megapascals (MPa), using a contact angle of 130° with a mercury surface tension of 474 dyne / cm at 25 °C.

[0017] As used herein, the term “pore volume” is defined as the total pore volume of the catalyst measured using the mercury intrusion method measured at pressures between atmospheric pressure and a pressure of about 412 MPa. The reference herein to median pore diameter (MPD) corresponds to the median pore diameter calculated as the weighted average pore diameter, where the weight is by surface area. The term “micropore” as used herein denotes pores having a pore diameter of less than 250 A. The term “mesopore” as used herein denotes pores having a pore diameter of between 250 A to 1,000 A. The term “macropore” as used herein denotes pores having a pore diameter equal or greater than 1 ,000 A.

[0018] Heavy hydrocarbon feedstocks such as, for example, vacuum tower bottoms and residue oils, are generally more difficult to hydrotreat to remove components such as sulfur, nitrogen, metals, and carbon compared to lighter hydrocarbon feedstocks (e.g., distillates and naphtha feedstocks). Hydroprocessing of heavy hydrocarbon feedstock generally require specially designed catalysts that are different from those used for treating the lighter hydrocarbon feedstocks for the refining / upgrading of these heavier feeds to be economical. Accordingly, embodiments of the present disclosure provide an improved self-activating hydroprocessing catalyst useful for the hydroprocessing of heavy hydrocarbon feedstocks, in particular, feedstocks having high sulfur and metal concentrations. Present embodiments also include a method of making and using the selfactivating hydroprocessing catalysts.

[0019] Catalysts used for the catalytic hydroconversion of heavy hydrocarbon feedstocks (e.g., feedstock boiling above about 370 °C) in fixed bed processes may become deactivated over time due to deposition of metals on catalyst surfaces and pores. To maintain a desired catalytic activity of the catalyst, a reaction temperature is increased, or the used catalyst is replaced with fresh catalyst. However, there are undesirable costs associated with increasing reaction temperatures and / or catalyst replacement. Specifically, in fixed bed catalytic hydroconversion,the system is shut down to remove the used catalyst and replace it with fresh catalyst once the activity of the catalyst decreases to an undesirable level. This decreases the efficiency of the fixed bed catalytic hydroconversion due to system shut down and catalyst replacement process that result in lost system run time. Therefore, it would be advantageous to develop a catalyst that maintains the desired activity over time without having to increase the reaction temperature and / or frequently replacing. The inventive catalyst disclosed herein has a unique combination of specifically defined physical properties and catalytic metal loadings that result in self-activating properties and desired catalytic activity and stability.

[0020] It is well known that a catalyst’s pore structure affects catalyst performance. For example, catalyst activity, stability, selectivity, and physical strength are all impacted by the overall pore structure of the catalyst. The pore structure of the catalyst is determined by the respective volume of micropores, mesopores, and macropores that make up the total pore volume (TPV) of the catalyst. The respective volume of each of the micropores, mesopores, and macropores that make up the TPV of the catalyst directly or indirectly impact the overall performance of the catalyst. For example, the micropore volume affects the surface area and catalytic performance, such as, for example, hydrodesulfurization, hydrodenitrogenation, and hydrogenation, the mesopore volume provides diffusion channels for a flow of heavy hydrocarbon feedstock through the catalyst pore structure, and the macropore volume provides space for adsorbing contaminant metals from the feedstock as well as the generated insoluble coke materials, it also significantly impacts the hydrodemetallization activity. Therefore, to improve the overall performance of the catalyst, a balanced ratio of micropores, mesopores, and macropores is particularly important.

[0021] The ratio (i.e., the pore distribution) between the micropores, mesopores, and macropores of the catalyst may be tailored based on properties of the heavy hydrocarbon feedstock. For example, catalysts having a pore distribution in which less than 50 vol.% of the TPV is in pores having a diameter less than 250 A and greater than 30 vol.% of the TPV is in pores having pore diameters greater than 1,000 A may have undesirable performance with respect to hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and hydrogenation. In contrast, catalysts having a pore distribution in which more than 80 vol.% of the TPV has a diameter lessthan 250 A is desirable for deeper HDS and HDN. That is, these catalysts remove greater than 95 wt.% of sulfur and nitrogen in the feedstock. However, due to deposition of coke on catalyst surfaces and accumulation of metal deposits (nickel (Ni) and vanadium (V)) on catalyst pore surfaces, catalysts having greater than 80% of the TPV in micropores may have lower hydrodemetallization (HDM) activity and a much shorter lifespan than catalysts having a larger percentage of the TPV in macropores. Therefore, the balance of pore diameters in the catalyst pore structure is important for a fixed bed (FB) residue catalyst.

[0022] The inventive catalyst of the present disclosure has a catalyst composition that is useful in hydroprocessing (e.g., HDS and hydrodemetallization) and hydroconversion of heavy hydrocarbon feedstocks and uniquely balances the metal content and pore structure to provide improved performance and stability compared to typical catalysts. The disclosed catalyst has particular application as a fixed bed catalyst used in fixed bed hydroconversion processes. As discussed in further detail below, the inventive catalyst disclosed herein combines an optimized active metal ratio, surface area, and meso- and macroporosity that result in improved HDS stability (e.g., slow catalyst decay and maintains high activity after aging) and performance, and selfactivation along with maximized and stable metal removal capacity compared to typical catalysts.

[0023] U.S. Patent No. 7,169,294 (Abe) discloses that catalysts having above 2 vol. % of their pore volume in pores greater than 4000 A have decreased catalyst strength and result in undesirable desulfurization activity. Therefore, catalysts used for fixed bed hydroconversion processes generally have less than 2 vol. % of their pores present in pores greater than 4000 A. However, the catalyst disclosed herein has more than 5 vol.% of pores present in pore having greater than 4000 A. The stability of the inventive catalyst disclosed herein is impacted by the macropores being present in pores having a pore diameter of greater than 5000 A. An important aspect is that it is desirable for the catalyst to include macropores having pore diameters exceeding 5000 A; such pores provide porosity for metal complexes in the feedstock to enter the pores, thereby facilitating demetallization of the feedstock. It is, therefore, desirable that from approximately 5 vol.% to 15 vol.% of the total pore volume is present in pores having a diameter greater than 5000 A.

[0024] The inventive catalyst disclosed herein is a co-mulled mixture of an inorganic component and a metal component. As should be noted, the co-mulled mixture may include additional components such as binders and other additives without departing from the scope of the present disclosure. The inorganic component includes an inorganic oxide material such as, for example, alumina, silica, aluminosilcates, or the like and combinations thereof. The amount of the inorganic oxide material in the co-mulled mixture is such to provide in the range of from approximately 70 wt.% to approximately 92.5 wt.% inorganic oxide material in a final calcined mixture / particle or hydroprocessing catalyst with the weight percent being based on the total weight of the calcined mixture or hydroprocessing catalyst. Preferably, the amount of the inorganic oxide material in the calcined mixture is in the range of from 72 to 91 wt.%, and, most preferably, from 74 to 90 wt.%.

[0025] As discussed above, the co-mulled mixture includes a metal component. The metal component includes one or more metals that facilitate hydroconversion of the heavy hydrocarbon feedstock. For example, the metal component may include a Group VIB metal, such as molybdenum, and a Group VIII metal, such as nickel. The concentrations of these metals in the final catalyst composition are important to the performance of the catalyst as well as its unique physical properties (e.g., surface area, mesoporosity, and macroporosity). For example, the nickel content of the calcined particle, thus, the hydroprocessing catalyst, is in a range of from 0 - 2.0 wt.% of the total weight of the calcined particle, calculated as metal, regardless of its actual form. For example, the nickel content of the calcined particle may be in the range of from 0-1.8 wt.%. In particular, the nickel content of the calcined particle is preferably less than 1.6 wt.%. It is more desirable for the nickel to be present in the calcined particle in an amount less than 1.4 wt.%. The atomic ratio of nickel (Ni) to molybdenum (Mo) of the calcined particle is between approximately 0 to approximately 0.5. This atomic ratio is calculated and presented on an elemental basis. For example, in a preferred embodiment, the atomic ratio of Ni:Mo is in a range of approximately 0 to approximately 0.30. The Mo content of the calcined particle (i.e., the hydroprocessing catalyst) is in the range of from 0.1-20 wt.% of the total weight of the calcined particle, calculated as metal regardless of its actual form. In particular, the Mo content of the calcined particle is preferably greater than 2 wt.% and less than 18 wt.% of the total weight of the calcined particle. It is moredesirable for the Mo to be present in the calcined particle in an amount in the range from 4 wt.% to 15 wt.% of the total weight of the calcined particle.

[0026] The metal and inorganic components, along with other starting materials (e.g., binders, fdlers, etc.) are mixed to form the co-mulled mixture. The co-mulled mixture is extruded into a desired geometric shape (e.g., sphere, cylinder, lobed, etc.), thereby forming a particle that is calcined to generate a calcined catalyst (e.g., the hydroprocessing catalyst).

[0027] An important physical feature of the catalyst disclosed herein is the ratio of microporosity and macroporosity. Unlike typical fixed bed residue catalysts, the self-activating catalyst disclosed herein has a significant portion of the TPV of the catalyst contained in pores having a diameter greater than 1,000 A. For example, the inventive catalyst has in a range of between 15 vol.% and 25 vol.% of the TPV contained in pores having a diameter greater than 1,000 A. This macroporosity, in combination with the active metal ratio and surface area provided by the micropore structure, provides advantageous catalytic activity (e.g., HDS and HDM), while also promoting self-activation compared to typical catalysts.

[0028] The disclosed self-activating catalyst has a bimodal pore structure with a first major portion of the pores being micropores and another major portion of the pores being macropores. For example, the catalysts include a first mode of the pore within the range of from 40 A to 250 A, and a second mode that is equal to or greater than 1,000 A. In one embodiment, the bimodal pore structure of the inventive catalyst preferably has a first major portion of pores having a mode within the range of from 50 A to 150 A and a second major portion of pores having a mode within the range of from 1,000 A to 20,000 A. More preferably, the first major portion of pores have a mode within the range of from 70 A to 120 A and the second major portion of pores have a mode within the range of from 1,000 A to 10,000 A. As used herein, the term “mode” is intended to denote the pore diameter where local maximum intensity of the pore size distribution is achieved. As should be noted, the mode of the pore is different from the median pore diameter (MPD).

[0029] The catalyst of the present disclosure also has a total pore volume of equal to or greater than 0.60 cubic centimeters (cc) / gram (g), cc / g. Preferably, the TPV of the disclosed catalyst is in the range of between 0.65 cc / g and 1 cc / g. The percentage of the total pore volume of the catalyst contained in pores of diameters less than 250 A is in the range of from 60 vol.% to85 vol.% of the TPV of the catalyst. Preferably, in the range of from 65 vol.% to 80 vol.% of the TPV of the catalyst is present in pores having diameters less than 250 A. As discussed above, the micropore structure (i.e., microporosity) of the catalyst impacts the surface area of the catalyst. Therefore, the volume of pores having diameters less than 250 A that make up the TPV of the catalyst is such that the catalyst has a surface area of in the range of greater than 150 and less than 240 square meters (m2) / gram (g), m2 / g. The TPV of typical catalysts is less than 0.8 cc / g, but the catalyst of this invention has TPV higher than 0.80 cc / g, due to a significant portion (e.g., 15-25 vol.%) of the total pore volume being present in pores having diameters greater than 1000 A. By boosting the TPV from approximately 0.80 cc / g to greater than approximately 0.84 cc / g while also maintaining the same microporosity as in the catalyst of the present disclosure, macroporosity is gained without losing surface area and catalyst activity.

[0030] As discussed above, the macroporosity of the inventive catalyst affects the capacity of the catalyst for removing certain metal contaminants (e.g., vanadium, nickel, iron, etc.). Therefore, it is desirable for the catalyst to have a macroporosity that maximizes removal of metal contaminants. Accordingly, in preferred embodiments of the catalyst, at least 15 vol.% of the total pore volume is contained within macropores having a diameter greater than 1,000 A. In addition, the catalyst disclosed herein has more than 1 vol.% of its total pore volume contained in pores of diameters greater than 5,000 A. Preferably, in a range of from 1 vol.% to 15 vol.% of the total pore volume of the catalyst is in its pores having diameters greater than 5,000 A. The macroporosity of the inventive self-activating catalyst disclosed herein provides for a metal uptake capacity that is greater than existing fixed bed catalysts.

[0031] As should be appreciated, it is important to have the proper balance between the volume of micropores and macropores in the total pore volume such that the micropores provide a surface area that facilitates deposition of the Group VIII metal and the Group VIB metal on surfaces of the catalyst and the macropores remove the metal contaminants in the heavy hydrocarbon feedstock. For example, the more macropores that make up the total pore volume of the catalyst, the less volume of micropores the catalyst will have. As such, because the catalyst does not have a sufficient volume of micropores contained in its total pore volume, the surface area of the catalyst will be low (e.g., less than 150 square meters (m2) / gram (g)). Therefore, theGroup VIII and Group VIB metals, which affect catalytic activity, and stability, may not be exposed to the heavy hydrocarbon feedstock to allow catalytic reactions to occur. Accordingly, conversion of the hydrocarbon feedstock into lighter distillate fractions may be undesirably low.

[0032] The catalyst disclosed herein may be prepared via a one-step co-mulling process. For example, the starting materials are mixed by co-mulling the components to form a co-mulled mixture. The starting materials in the preparation of the co-mulled mixture, in one embodiment, include at least one Group VIB metal compound, such as molybdenum, at least one Group VIII metal compound, such as nickel, alumina material, and, optionally, a poly-organic (e.g., polyacrylamides such as Superfloc® and the like). The Group VIB metal compound is preferably a molybdenum oxide (e.g., molybdenum trioxide), a molybdenum salt (e.g., ammonium dimolybdate (ADM)), or any other suitable molybdenum compound in the form of finely divided particles that may be as a dry powder or as particles in a suspension or slurry. The Group VIII metal compound is selected from a group of suitable nickel compounds such as, but not limited to, nickel oxide, a nickel salt (e.g., nickel nitrates, nickel hydroxides, nickel chlorides, and nickel acetates), any other nickel compound that is capable of being mixed with the other components of the co-mulled mixture that is shaped into a particle. In a preferred embodiment, the nickel component is nickel nitrate.

[0033] The co-mulled mixture may also include other components such as, but not limited to, organic additives, acid, and a solvent (e.g., water). By way of non-limiting example, the organic additives include flocs and the acid may include solutions of nitric acid. The co-mulled mixture is extruded into a shaped particle, followed by drying and calcination to form the calcined particle of the invention.

[0034] The formation of the co-mulled mixture may be done by any method or means known to those skilled in the art. These include the use of such suitable types of solids-mixing machines as tumblers, stationary shells or troughs, muller mixers, which are either batch type or continuous type, and impact mixers, and the use of such suitable types of either batch-wise or continuous mixers for mixing solids and liquids or for the formation of paste-like mixtures that are extrudable. Suitable types of batch mixers include, but are not limited to, change-can mixers, stationary -tank mixers, double-arm kneading mixers that are equipped with any suitable type ofmixing blade. Suitable types of continuous mixers include single or double screw extruders, and trough-and-screw mixers.

[0035] The mixing of starting materials of the calcined particle may be conducted for any suitable time-period necessary to properly homogenize the co-mulled mixture. Generally, the blending time may be in the range of upwardly to 2 or more than 3 hours.

[0036] The term “co-mulling” as used herein is intended to mean that at least the starting materials are mixed together to form a mixture of the individual components of the co-mulled mixture that is preferably a substantially uniform or homogeneous mixture of the individual components of such co-mulled mixture. This term is intended to be broad enough in scope to include the mixing of the starting materials to yield a paste that exhibits properties making it capable of being extruded or formed into extrudate particles by any of the known extrusion methods. But, also, the term is intended to encompass the mixing of the starting materials to yield a mixture that is preferably substantially homogeneous and capable of being agglomerated into formed particles. Examples of the formed particles include spheroids, pills or tablets, cylinders, irregular extrusions or merely loosely bound aggregates or clusters, by any of the methods known to those skilled in the art, including, but not limited to, molding, tableting, pressing, pelletizing, extruding, and tumbling.

[0037] Once the starting materials of the calcined particle are properly mixed and formed into the shaped or formed particles, a drying step may advantageously be used for removing certain quantities of water or volatiles that are included within the co-mulled mixture or formed particles. The drying of the formed particles may be conducted at any suitable temperature for removing excess water or volatiles, but, preferably, the drying temperature will be in the range of from about 75 °C to 250 °C. The time period for drying the particles is any suitable period of time necessary to provide for the desired amount of reduction in the volatile content of the particles prior to the calcination step.

[0038] The dried or undried particles are calcined in the presence of an oxygen-containing fluid, such as air, at a calcination temperature that provides a final calcined particle having the required pore structure and enhanced catalytic properties that are described herein. The dried particle of the invention is calcined at a temperature is in the range of from 677 °C to 899 °C. Thepreferred calcination temperature is in the range of from 704 °C to 871 °C, and, more preferred, from 732 °C to 857 °C.

[0039] The calcined particle is particularly useful as a hydroprocessing catalyst for use in the hydroprocessing of a heavy hydrocarbon feedstock stream that has organic metals such as nickel and vanadium compounds, and sulfur. Prior to its use, the calcined particle may, but is not required to, be sulfided or activated by any of the methods known to those skilled in the art. Generally, in its use in the hydroprocessing of a heavy hydrocarbon feedstock, the calcined particle is contained within a reaction zone, such as that which is defined by a reactor vessel, wherein the heavy hydrocarbon feedstock is contacted with the calcined particle under suitable hydroprocessing reaction conditions and from which a treated hydrocarbon or heavy hydrocarbon conversion product is yielded. The heavy hydrocarbon feedstock used in the process disclosed herein may be derived from any of the high boiling temperature petroleum cuts such as atmospheric tower gas oils, atmospheric tower bottoms, vacuum tower gas oils, and vacuum tower bottoms or resid.

[0040] The heavy hydrocarbon feedstock further may include a significantly high sulfur content. One of the special features of the disclosed catalyst is that it also provides for the desulfurization of the heavy hydrocarbon feedstock. In particular, the disclosed catalyst provides for the desulfurization of the heavy feedstock having a significantly high sulfur content. Such a sulfur content is typically much greater than 1 weight percent. For example, in certain embodiments, the sulfur content of the heavy hydrocarbon feedstock may exceed 2 weight percent, and with such a heavy hydrocarbon feedstock, the sulfur content may be in the range of from approximately 2 to 8 wt.%. In one embodiment, the heavy hydrocarbon feedstock has an especially high sulfur content exceeding approximately 3 or even 4 wt.% and being in the range of from approximately 3 to 7 wt.% or even from approximately 4 to 6.5 wt.%. The sulfur content of the heavy hydrocarbon feedstock is primarily in the form of organic sulfur-containing compounds, which may include, for example, mercaptans, substituted or unsubstituted thiophenes, heterocyclic compounds, or any other type of sulfur-containing compound. When referring herein to the sulfur content of either the heavy hydrocarbon feedstock or the treated hydrocarbon or heavy hydrocarbon conversion product, the weight percents are determined by the use of testing methodASTM D-4294. The catalyst disclosed herein facilitates desulfurization so as to provide for a treated hydrocarbon product or a heavy hydrocarbon conversion product having a reduced sulfur content, such as a sulfur content of less than 1 weight percent, preferably, less than 0.75 wt.%, and, more preferably, less than 0.5 wt.%.

[0041] The disclosed self-activating catalyst having improved stability may be used in hydroprocessing heavy hydrocarbon feedstocks to provide for simultaneous desulfurization, and denitrogenation. In this process, the heavy hydrocarbon feedstock is contacted with the selfactivating catalyst disclosed herein under suitable hydrodesulfurization and hydroconversion process conditions to yield the heavy hydrocarbon conversion product.

[0042] As discussed above, the macroporosity of the catalyst disclosed herein facilitates removal of undesirable metals contained in the heavy hydrocarbon feedstock. The heavy hydrocarbon feedstock may contain undesirable metals such as nickel and vanadium. The nickel content of the heavy hydrocarbon feedstock is typically in the form of organic nickel compounds. The nickel concentration of the heavy hydrocarbon feedstock may be in the range of from 2 ppmw to 250 ppmw. More typically, the heavy hydrocarbon feedstock has a concentration of nickel that is in the range of from 5 ppmw to 225 ppmw, and, most typically, the nickel concentration is in the range of from 7 ppmw to 200 ppmw. The vanadium concentration in the heavy hydrocarbon feedstock is generally in the range of from 5 ppmw to 350 ppmw. More typically, the vanadium concentration of the heavy hydrocarbon feedstock is in the range of from 10 ppmw to 300 ppmw. The macropore structure of the catalyst disclosed herein provides for demetallization, and, thus, the removal of nickel and vanadium from the heavy hydrocarbon feedstock.

[0043] The calcined particle (high stability self-activating catalyst) of the present disclosure may be employed as a part of any suitable reactor system that provides for the contacting of the catalyst with the heavy hydrocarbon feedstock under suitable hydroprocessing conditions that may include the presence of hydrogen and an elevated total pressure and temperature. Such suitable reaction systems can include fixed catalyst bed systems, ebullating catalyst bed systems, slurried catalyst systems, and fluidized catalyst bed systems. The catalyst disclosed herein is particularly useful as a fixed bed catalyst used in fixed bed reactor systems. The fixed bed reactor system is described in greater detail below with respect to the FIG. 1.

[0044] The catalyst disclosed herein may be used in a process that generally operates at a hydroprocessing (hydroconversion and hydrodesulfurization) reaction pressure in the range of from 2298 kPa to 20,684 kPa, preferably from 10,342 kPa to 17,237 kPa, and, more preferably, from 12,411 kPa to 15,513 kPa. The hydroprocessing reaction temperature is generally in the range of from 340 °C to 480 °C, preferably, from 360 °C to 455 °C, and, most preferably, from 370 °C to 420 °C.

[0045] The flow rate at which the heavy hydrocarbon feedstock is charged to a reaction zone of the reactor system is generally such as to provide a liquid hourly space velocity (LHSV) in the range of from 0.01 hr1to 3 hr’1. The term “liquid hourly space velocity”, as used herein, means the numerical ratio of the rate at which the heavy hydrocarbon feedstock is charged to the reaction zone in volume per hour divided by the volume of the reaction zone to which the heavy hydrocarbon feedstock is charged. The preferred LHSV is in the range of from 0.02 hr’1to 2 hr’1, more preferably, from 0.05 hr’l to 1.5 hr’1and, most preferably, from 0.1 hr’1to 0.7 hr’1.

[0046] It is preferred to charge hydrogen along with the heavy hydrocarbon feedstock to the reaction zone. In this instance, the hydrogen is sometime referred to as hydrogen treat gas. The hydrogen treat gas rate is the amount of hydrogen relative to the amount of heavy hydrocarbon feedstock charged to the reaction zone and generally is in the range upwardly to 1781 m3 / m3. It is preferred for the treat gas rate to be in the range of from 89 m3 / m3to 1781 m3 / m3, more preferably, from 178 m3 / m3to 1602 m3 / m3, and, most preferably, from 356 m3 / m3to 1425 m3 / m3.

[0047] FIG. 1 is a schematic representation of a fixed bed reactor system 20 in which the catalyst of the present disclosure may be used. The fixed bed reactor system includes elongated vessel 24 that defines several zones such as a contacting zone for contacting a heavy hydrocarbon feedstock under suitable hydroconversion reaction conditions with the high stability catalyst and a separation zone for the separation of a hydrotreated heavy hydrocarbon product from the high stability catalyst.

[0048] Within the elongated vessel 24 is a fixed bed of a high stability catalyst bed 26 having a bed level. While in the illustrated embodiment, a single catalyst bed 26 is shown, the elongated vessel 24 may have multiple catalyst beds 26. A reactor feed 30 having a heavy hydrocarbon feedstock and hydrogen is introduced into an inlet 32. As should be appreciated, theheavy hydrocarbon and hydrogen in the reactor feed 30 may be introduced into the elongated vessel as a combined feed or separate feeds. The reactor feed 30 passes through the catalyst bed 26 and contacts catalyst particles 36 within the catalyst bed 26 to generate a heavy hydrocarbon conversion product 46, and the heavy hydrocarbon conversion product, which exits the elongated vessel 24 by way of conduit 48.

[0049] Set forth below is an illustrative example of the manner in which the catalyst disclosed herein is prepared and its composition. Performance of the catalyst and a comparative reference catalyst is also provided. As should be appreciated, the illustrative example is not to be constmed as limiting the scope of the present disclosure.Inventive Catalyst Composition

[0050] Inventive catalyst 1 was prepared by combining 868.6 parts by weight of alumina, having loss on ignition (LOI) of 22.8 wt.%, 188.8 parts by weight crushed regenerated Ni / Mo / P hydrotreating catalyst, 54.1 parts by weight molybdenum tri oxide (MoOs) powder, and within a Muller mixer along with 19.9 parts by weight 68 wt.% concentrated nitric acid, 9 parts by weight of an extrusion aid, and 1167 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 60.9 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of two hour at a temperature of 120 °C. The dried extrudate particles were calcined in air for two hours with a maximum temperature of 837.8 °C. The final calcined mixture contained 0.8 wt.% nickel metal (1.0 wt.% as NiO), 7.0 wt.% molybdenum metal (10.5 wt.% as MoOa).

[0051] Inventive catalyst 2 was prepared by combining 861 parts by weight of alumina, having loss on ignition (LOI) of 22.8 wt.%, 188.8 parts by weight crushed regenerated Ni / Mo / P hydrotreating catalyst, 40.4 parts by weight molybdenum trioxide (MoOs) powder, and within a Muller mixer along with 25.7 parts by weight 68 wt.% concentrated nitric acid, 9 parts by weight of an extrusion aid, and 1049.6 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 60 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of two hoursat a temperature of 120 °C. The dried extrudate particles were calcined in air for two hours with a maximum temperature of 760 °C. The final calcined mixture contained 2.5 wt.% nickel metal (3.2 wt.% as NiO), 6.1 wt.% molybdenum metal (9.2 wt.% as MoOs).Comparison Catalyst Composition

[0052] The comparison catalyst composition A (Reference Catalyst A) was prepared by combining 864.6 parts of alumina, having an LOI of 22.6 wt.%, 188.8 parts by weight crushed regenerated Ni / Mo / P hydrotreating catalyst, and 54.1 parts by weight MoOs within a Muller mixer along with 19.9 parts by weight 68 wt.% concentrated nitric acid, 9 grams by weight of extrusion aid, and 1113.7 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 60 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of two hours at a temperature of 120 °C. The dried extrudate particles were calcined in air for a period of two hours with a maximum temperature of 760 °C. The final calcined mixture contained 0.7 weight percent nickel metal (0.9 wt.% as NiO), 6.9 wt.% molybdenum metal (10.4 wt.% as MoOs).

[0053] The comparison catalyst composition B (Reference Catalyst B) was prepared by combining 827.4 parts by weight of alumina, having LOI of 22.6 wt.%, 74.3 parts by weight nickel nitrate (Ni(NO3)2), 188.8 parts by weight crushed regenerated Ni / Mo / P hydrotreating catalyst, and 67.3 parts by weight MoOs within a Muller mixer along with 32.1 parts by weight 68 wt.% concentrated nitric acid, 18 parts by weight of extrusion aid, and 1237 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 63 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of one hour at a temperature of 120 °C. The dried extrudate particles were calcined in air for a period of two hours with a maximum temperature of 821.1 °C. The final calcined mixture contained 2.4 weight percent nickel metal (3.1 wt.% as NiO), 8.2 wt.% molybdenum metal (12.4 wt.% as MoOs.

[0054] The comparison catalyst composition C (Reference Catalyst C) was prepared by combining 861.1 parts of alumina, having an LOI of 22.6 wt.%, 188.8 parts by weight crushedregenerated Ni / Mo / P hydrotreating catalyst, 75.5 parts by weight nickel nitrate (Ni(NO3)2), and 40.4 parts by weight MoOs within a Muller mixer along with 25.7 parts by weight 68 wt.% concentrated nitric acid, 9 parts by weight by weight of extrusion aid, and 1049.6 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 60 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of two hours at a temperature of 120 °C. The dried extrudate particles were calcined in air for a period of two hours with a maximum temperature of 816 °C. The final calcined mixture contained 2.5 weight percent nickel metal (3.2 wt.% as NiO), 6.1 wt.% molybdenum metal (9.2 wt.% as MoOs).

[0055] The comparison catalyst composition D (Reference Catalyst D) was prepared by combining 861.1 parts of alumina, having an LOI of 22.6 wt.%, 188.8 parts by weight crushed regenerated Ni / Mo / P hydrotreating catalyst, 75.5 parts by weight nickel nitrate (Ni(NOs)2), and 40.4 parts by weight MoOs within a Muller mixer along with 35.3 parts by weight 68 wt.% concentrated nitric acid, 9 parts by weight by weight of extrusion aid, and 983.9 parts by weight deionized water to generate a mixture. The mixture was mulled for 35 minutes to generate a co-mulled mixture. The co-mulled mixture had an LOI of 59 wt. %. Following mixing, the co-mulled mixture was then extruded using 1.3 mm trilobe dies to form 1.3 mm trilobe extrudate particles. The extrudate particles were dried in air for a period of two hours at a temperature of 120 °C. The dried extrudate particles were calcined in air for a period of two hours with a maximum temperature of 760 °C. The final calcined mixture contained 2.4 weight percent nickel metal (3.1 wt.% as NiO), 6.0 wt.% molybdenum metal (9.0 wt.% as MoOs).

[0056] The following Table 1 presents the pore structure properties of the catalyst of the present disclosure and comparison catalysts.TABLE 1 - Catalyst Pore Structure PropertiesCatalyst Performance Testing

[0057] The catalysts described above were evaluated in a lab scale reactor using heavy feedstock as follows: catalyst was loaded into a 127 cm long stainless-steel reactor tube having an internal diameter (ID) of 1.90 cm. The reactor tube was equipped with thermocouples placed in a 0.635 cm thermowell inserted concentrically into the catalyst bed, and the reactor tube was held within a 132 cm long 5-Zone furnace with each of the Zones being separately controlled based on a signal from a thermocouple. The loaded catalyst (i.e., catalyst bed) was activated by feeding at 4.14 megapascals (MPa) of a diesel spiked to 2.5 wt.% of sulfur with an industrial sulfiding agent (e.g., dimethyl disulfide (DMDS), di-tert-nonyl polysulfide (TNPS), and the like) to the reactor tube at a rate of 1.5 h'1LHSV as well as H2 in a H2 to Oil ratio of 34 standard cubic meters (scm (1200 scf) / barrel (bbl), while incrementally increasing the reactor temperature at a rate of 38 °C / hr up to 204 °C. The catalyst bed was maintained at a temperature of 204 °C for two hours after which the temperature was incrementally increased at a rate of 38 °C / hr to a temperature of 315 °C, where it was held for one hour followed again by an incremental increase in the temperature at a rate of 24 °C / hr up to a temperature of 371 °C, where it was held for two hours before cooling the catalyst bed temperature down to the ambient temperature.

[0058] Following activation, the catalyst bed was pressured with H2 at 13 MPa, and the temperature of the catalyst bed was incrementally increased at a rate of 38 °C / hr to 204 °C. The reactor tube was then charged with Middle Eastern long residue feedstock while the temperature was held at 204 °C for one hour. The catalyst bed temperature was then incrementally increased at a rate of 10 °C / hr up 371° C, from which point the run was started. The properties of the feed and process conditions are summarized in Table 2 and Table 3, respectively.TABLE 2 - Properties of the feed used to evaluate the catalystsTABLE 3 - Process conditions used to evaluate the catalysts

[0059] FIGS. 2 and 3 demonstrate performance results of the disclosed catalyst and the comparative reference catalysts. FIG. 2 is a bar graph illustrating the relative hydrodesulfurization (HDS) activity of the inventive catalysts 1 and 2 and reference catalyst A-D at 500 hr, 1000 hr, and 1500 hr. As shown in FIG. 2, the activity of the inventive catalysts 1 and 2 for desulfurization (e.g., HDS) of the heavy hydrocarbon feedstock is better at 1000 hr and 1500 hr compared to reference catalysts A. Notably, after 500 hrs on stream, the inventive catalysts 1 and 2 selfactivated and shown by an increase in activity from 500 hr to 1000 hr, whereas reference catalyst A-D all experienced significant activity loss. While reference catalyst D has a higher HDS activity compared to inventive catalysts 1 and 2, this catalyst is not self-activating as the HDS activity decreases over time. Moreover, as shown in the bar graph illustrated in FIG. 3, reference catalyst D had undesirable hydrometallization (HDM) activity compared to the inventive catalysts 1 and 2. As should be appreciated, not only do the inventive catalyst 1 and 2 have self-activating properties and improved activity for HDS, the amount of metal loading of these catalyst is less than that of the comparative catalysts B and C. This suggests that the pore structure, and inparticular the balance between the micropore and macropore volume, contributes to the improved performance of the inventive catalysts 1 and 2.

[0060] Not only did the inventive catalysts 1 and 2 of the present disclosure improve HDS, as discussed above, these catalysts also had improved stability compared to the comparative catalysts. For example, as shown in FIG. 3 ,the inventive catalysts 1 and 2 maintained HDM above 85 at 1000 hr and 1500 hr. In contrast, the HDM activity of the reference catalysts A and D was below 75 at 1000 hr, which is undesirable. While reference catalysts B and C had desirable HDM activity, the HDS of these catalysts was significantly less and undesirable compared to the inventive catalysts 1 and 2. Without being bound by theory, the improved HDS and stability (e.g., HDM) of the inventive catalysts 1 and 2 is believed to be attributed, in part, to the optimized pore structure and metal ratio compared to the reference catalysts A-D.

[0061] The technical effects of the catalyst disclosed herein are that with the combination of balanced and optimized active metal ratio and pore structure, the stability, hydrogenation activity, and metal removal capacity is improved compared to catalysts typically used for the fixed bed hydrogenation of heavy hydrocarbon feedstocks. For example, the activity of the Reference Catalysts for HDS and HDM decreases over time. However, the activity of the Inventive Catalyst increases with time for more than 1000 hrs on stream. The improved activity and stability of the inventive catalyst disclosed herein provides for a catalyst that does not need to be frequently replaced and / or require increases in process temperatures to maintain a desired conversion activity, thereby decreasing the overall cost for fixed bed hydroprocessing of heavy hydrocarbon feedstocks.

[0062] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

CLAIMS1. A catalyst used for converting a heavy hydrocarbon, wherein the catalyst comprises: an extrudate comprising a co-mulled mixture of: an inorganic oxide; and at least one metal from Group VIB and at least one metal from Group VIII of the Periodic Table of Elements, wherein an atomic ratio of the at least one metal from Group VIII to the at least one metal from Group VIB is in the range of from 0.0 to 0.3, and wherein the catalyst has a pore structure such that 15 vol.% to 25 vol.% of the total pore volume is present in pores of a diameter greater than l,000A and a surface area of that is greater than 150 square meters (m2) / gram (g) and less than 240 m2 / g.

2. The catalyst of claim 1, wherein the at least one metal from Group VIB is in the range of from 0.1 wt.% to 20 wt.% of the total weight of the catalyst.

3. The catalyst of claim 2, wherein the at least one metal from Group VIII is in a range of from 0.2 wt.% to 2.0 wt.% of the total weight of the catalyst.

4. The catalyst of any one of claims 1 to 3, wherein the at least one metal from Group VIII is nickel and the at least one metal from Group VIB is molybdenum5. The catalyst of any one of claims 1 to 4, wherein the total pore volume is between 0.65 cubic centimeters per gram (cc / g) and 1 cc / g.

6. The catalyst of any one of claims 1 to 5, wherein between 1 vol.% and 15 vol.% of the pores have a pore diameter greater than 5,000 A.

7. The catalyst of any one of claims 1 to 6, wherein the total pore volume of pores having a diameter of less than 250 A is in the range of 65 vol.% and 80 vol.%.

8. The catalyst of any one of claims 1 to 7, comprising a bimodal pore size distribution.

9. The catalyst of any one of claims 1 to 8, wherein a median pore diameter of the catalyst is higher than 70 A and lower than 120 A.

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