PROCESS FOR HYDROPROCESSING MATERIALS FROM RENEWABLE SOURCES

Abstract

A process for hydroprocessing a renewable feedstock in a fixed-bed reactor system having at least one catalytic bed involves directing a downward flow of the renewable feedstock to a filtering zone having top-open interstitial portions to receive the downward flow and top-covered annular portions that are in fluid communication with a headspace between the filtering zone and a catalytic zone. The feedstock flows from the interstitial portions to the annular portions through a filtering material disposed between the interstitial portions and the annular portions, resulting in a filtered feedstock, which then flows to the catalytic zone. In the catalytic zone, filtered feedstock is reacted under hydroprocessing conditions sufficient to cause a reaction selected from the group consisting of hydrogenation, hydrodeoxygenation, hydrodenitrogenation, hydrodesulphurization, hydrodemetalation, hydrocracking, hydroisomerization, and combinations thereof.

Claims

1. A process for hydroprocessing a renewable feedstock in a fixed-bed reactor system having at least one catalytic bed, the process comprising the steps of: introducing a renewable feedstock in a downward flow into a top portion of a fixed-bed reactor; directing the downward flow of the renewable feedstock to a filtering zone having top-open interstitial portions to receive the downward flow and top-covered annular portions that are in fluid communication with a headspace between the filtering zone and a catalytic zone; passing the downward flow from the interstitial portions to the annular portions through a filtering material disposed between the interstitial portions and the annular portions, resulting in a filtered feedstock; allowing the filtered feedstock to flow downwardly to the catalytic zone; and reacting the filtered feedstock in the catalytic zone under hydroprocessing conditions sufficient to cause a reaction selected from the group consisting of hydrogenation, hydrodeoxygenation, hydrodenitrogenation, hydrodesulphurization, hydrodemetalation, hydrocracking, hydroisomerization, and combinations thereof.

2. The process of claim 1, wherein the catalytic zone comprises a grading zone and a catalyst zone.

3. The process of claim 2, wherein the grading zone has a start-of-run catalytic activity in a range of from 0 to 50% of the start-of-run catalytic activity of the catalyst in the catalyst zone.

4. The process of claim 3, wherein the grading zone has a first grading bed and a second grading bed, wherein the start-of-run catalytic activity of the first grading bed is less than the start-of-run catalytic activity of the second grading bed.

5. The process of claim 4, wherein the first grading bed has a start-of-run catalytic activity in a range of from 0 to 30% of the start-of-run catalytic activity of the catalyst in the catalyst zone, and the second grading bed has a start-of-run catalytic activity in a range of from 30 to 50% of the start-of-run catalytic activity of the catalyst in the catalyst zone.

6. The process of claim 1, wherein the renewable feedstock is selected from the group consisting of one or more bio-renewable fats and oils, liquid derived from a biomass liquefaction process, liquid derived from a waste liquefaction process, and combinations thereof.

7. The process of claim 1, further comprising the step of distributing the downward flow of the renewable feedstock with a feed distributor in the top portion of the fixed-bed reactor above the filtering zone.

8. The process of claim 1, further comprising adding a petroleum-derived feedstock for co-processing with the renewable feedstock, preferably in an amount to produce a feed stream comprising from 30 to 99 wt. % renewable feedstock, preferably from 40 to 99 wt. % renewable feedstock.

9. The process of claim 1, wherein hydrogen is mixed with the renewable feedstock prior to the introducing step.

10. The process of claim 1, wherein the filtering material is selected from the group consisting of ceramics, preferably alumina, metals, and combinations thereof.

11. The process of claim 2, wherein the grading zone is comprised up catalytically inert material, catalytically active material, and combinations thereof.

12. The process of claim 1, wherein the interstitial portions are substantially closed to the headspace between the filtering zone and the catalytic zone.

13. The process of claim 1, wherein the hydroprocessing conditions at least comprise a process temperature in the range of from 200 to 400? C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The process of the present invention will be better understood by referring to the following detailed description of preferred embodiments and the drawings referenced therein, in which:

[0023] FIG. 1 is a schematic illustrating one embodiment of a fixed-bed reactor for implementing the process of the present invention, the reactor having a filtering zone and a catalytic zone;

[0024] FIG. 2 is a schematic illustrating another embodiment of a fixed-bed reactor for implementing the process of the present invention, the reactor having a filtering zone and a catalytic zone, where the catalytic zone has a grading zone and a catalyst zone;

[0025] FIG. 3 is a schematic illustrating a further embodiment of a fixed-bed reactor for implementing the process of the present invention, wherein the reactor has two grading beds and a catalyst zone;

[0026] FIGS. 4A and 4B are top plan views of example embodiments of the filtering zone of FIGS. 1-3;

[0027] FIGS. 5A and 5B are side elevational cross-sectional views of one embodiment of the filtering zone of FIGS. 4A and 4B, respectively;

[0028] FIGS. 6A and 6B are side elevational cross-sectional views of another embodiment of the filtering zone of FIGS. 4A and 4B, respectively; and

[0029] FIGS. 7A-7C illustrate one embodiment of the filtering zone during operation.

DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention provides a process for hydroprocessing a renewable feedstock that improves cost effectiveness, energy efficiency and catalyst life. As discussed above, undesirable reactions and products caused by heating renewable feedstocks to desired reaction temperatures can cause fouling of a catalyst bed. Alternatively, or in addition, renewable feedstocks may contain undesirable particulate matter. Fouling and/or particulate matter increases pressure drop across a catalyst bed and/or reduces catalyst activity.

[0031] In accordance with the present invention, the renewable feedstock is fed through a filtering zone to capture fouling and/or particulate matter before flowing to the catalytic zone. By reducing fouling and/or particulate matter before flowing to the catalyst beds, pressure drop across catalyst bed(s) in the fixed-bed reactor is reduced. In a preferred embodiment, the catalytic zone is provided with a grading zone to further protect the catalyst, thereby improving catalyst life and reducing pressure drop effects that adversely affect cost and energy efficiency. The grading zone of the present invention is also used to manage the exothermicity of the hydroprocessing reactions.

[0032] The process of the present invention is important for the energy transition and can improve the environment by producing low carbon energy and/or chemicals from renewable sources, and, in particular, from degradable waste sources, whilst improving energy efficiency of the process.

[0033] As used herein, the terms renewable feedstock, renewable feed, and material from renewable sources mean a feedstock from a renewable source. A renewable source may be animal, vegetable, microbial, and/or bio-derived or mineral-derived waste materials suitable for the production of fuels, fuel components and/or chemical feedstocks.

[0034] A preferred class of renewable materials are bio-renewable fats and oils comprising triglycerides, diglycerides, monoglycerides, free fatty acids, and/or fatty acid esters derived from bio-renewable fats and oils. Examples of fatty acid esters include, but are not limited to, fatty acid methyl esters and fatty acid ethyl esters. The bio-renewable fats and oils include both edible and non-edible fats and oils. Examples of bio-renewable fats and oils include, without limitation, algal oil, brown grease, canola oil, carinata oil, castor oil, coconut oil, colza oil, corn oil, cottonseed oil, fish oil, hempseed oil, jatropha oil, lard, linseed oil, milk fats, mustard oil, olive oil, palm oil, peanut oil, rapeseed oil, sewage sludge, soy oils, soybean oil, sunflower oil, tall oil, tallow, train oil, used cooking oil, yellow grease, and combinations thereof.

[0035] Another preferred class of renewable materials are liquids derived from biomass and waste liquefaction processes. Examples of such liquefaction processes include, but are not limited to, (hydro)pyrolysis, hydrothermal liquefaction, plastics liquefaction, and combinations thereof. Renewable materials derived from biomass and waste liquefaction processes may be used alone or in combination with bio-renewable fats and oils.

[0036] The process of the present invention is most particularly advantageous in the processing of feed streams comprising substantially 100% renewable feedstocks. However, in one embodiment of the present invention, renewable feedstock may be co-processed with petroleum-derived hydrocarbons. Petroleum-derived hydrocarbons include, without limitation, all fractions from petroleum crude oil, natural gas condensate, tar sands, shale oil, synthetic crude, and combinations thereof. At a renewable feed content in a range of from 1-30 wt. %, the petroleum-derived hydrocarbons will generally provide a diluting effect and/or heat sink effect. Accordingly, the present invention is more particularly advantageous for a combined renewable and petroleum-derived feedstock comprising a renewable feed content in a range of from 30 to 99 wt. %, preferably from 40 to 99 wt. %.

[0037] FIG. 1 illustrates one embodiment of a fixed-bed reactor 12 for implementing the process of the present invention 10. A feed stream 14 comprising a renewable feedstock is introduced to a top portion of the fixed-bed reactor 12. The feed stream 14 is introduced in a downward flow, preferably with a hydrogen-containing gas stream. The hydrogen-containing gas stream may be mixed with the feed upstream of the feed inlet to the reactor 12.

[0038] Alternatively, the hydrogen-containing gas stream may be added to the reactor 12 independently, but concurrently, with the renewable feedstock. Preferably, the downward flow is dispersed downwardly and radially outwardly and downwardly by a feed distributor, such as an impingement plate (not shown).

[0039] The feed stream 14 is directed to a filtering zone 30, which, as will be discussed in more detail below, has top-open interstitial portions to receive the downward flow and top-covered annular portions that are in fluid communication with a headspace 16 between the filtering zone 30 and a catalytic zone 18.

[0040] Catalyst in the catalytic zone 18 is selected to catalyse hydroprocessing reactions including, without limitation, hydrogenation, hydrodeoxygenation, hydrodenitrogenation, hydrodesulphurization, hydrodemetalation, hydrocracking, hydroisomerization, and combinations thereof. The catalyst may be the same throughout the catalytic zone 18; optionally the catalytic zone 18 has a mixture of catalysts. The catalytic zone 18 may comprise a single catalyst bed or multiple catalyst beds. The catalyst may be the same throughout the single catalyst bed, optionally there is a mixture of catalysts, or different catalysts may be provided in two or more layers in the catalyst bed. In an embodiment of multiple catalyst beds, the catalyst may be same or different for each catalyst bed.

[0041] In a preferred embodiment, illustrated schematically in FIG. 2, the catalytic zone 18 is comprised of a grading zone 22 and a catalyst zone 24. The grading zone 22 and the catalyst zone 24 are depicted in FIG. 2 as being contiguous, but the grading zone 22 and the catalyst zone 24 may be in spaced-apart relationship. Each of the grading zone 22 and the catalyst zone 24 may independently be comprised of a single bed or multiple beds. For example, in the embodiment of FIG. 3, the grading zone 22 is comprised of a first grading bed 26 and a second grading bed 28.

[0042] The grading material in the grading zone 22 may be catalytically inert, have catalytic activity, or a combination thereof. A catalyst in the grading zone 22 may be the same type as, or a different catalyst than, the catalyst in the catalyst zone 24. But the catalyst in the grading zone 22 has a start-of-run catalytic activity that is less than the start-of-run catalytic activity of the catalyst in the catalytic zone 24. Preferably, the start-of-run catalytic activity of the grading zone 22 is in a range of from 0% to 50% of the start-of-run catalytic activity of the catalyst in the catalyst zone 24. In a more preferred embodiment, the feed is first exposed to a grading material having a start-of-run catalytic activity that is in a range of from 0% to 30% and then to a different grading material having a start-of-run catalytic activity that is in a range of from 30% to 50%, relative to the start-of-run catalytic activity of the catalyst zone 24. This embodiment may be accomplished by layers, beds, or combination thereof in the grading zone of FIG. 2.

[0043] In the embodiment of FIG. 3, the feed is first exposed to first grading bed 26 and then to a second grading bed 28, where the start-of-run catalytic activity of the first grading bed 26 is less than the start-of-run catalytic activity of the second grading bed 28. In a preferred embodiment, the first grading bed 26 has a grading material with a start-of-run catalytic activity that is in a range of from 0% to 30% of the start-of-run catalytic activity of the catalyst zone 24, while the second grading bed 28 has a grading material with a start-of-run catalytic activity that is in a range of from 30% to 50%, relative to the start-of-run catalytic activity of the catalyst zone 24.

[0044] The catalytic activity of the material in the grading zone 22 may be reduced relative to the catalyst zone 24 by (i) increasing the particle size of the catalyst to reduce diffusion of the feedstock through the bed, (ii) increasing pore size and/or reducing pore volume of the catalyst to reduce the surface area available for catalytic reaction, and/or (iii) reducing the active metal loading on the catalyst. Examples of suitable grading material include inert and catalytically active shaped, high-void aluminas (for example, SENTRY OPTITRAP SERIES? available from Shell as medallions, rings and lobes), Group VIII and/or Group VIB metals supported on larger particle size and/or larger pore size supports (for example, SENTRY INTERLAYER? and SENTRYSUPPORT? NiMo- and CoMo-promoted catalysts for grading between small diameter catalysts and larger reactor support media, and SENTRY MAXTRAP?).

[0045] The catalyst zone 24 favours hydroprocessing reactions including hydrogenation, hydrodeoxygenation, hydrodenitrogenation, hydrodesulphurization, hydrodemetalation, hydrocracking, hydroisomerization, and combinations thereof.

[0046] The hydroprocessing catalyst may be any catalyst known in the art that is suitable for hydroprocessing. Catalyst metals are often in an oxide state when charged to a reactor and preferably activated by reducing or sulphiding the metal oxide. Preferably, the hydroprocessing catalyst comprises catalytically active metals of Group VIII and/or Group VIB metals, including, without limitation, Pd, Pt, Ni, Co, Mo, W, and combinations thereof. Hydroprocessing catalysts are generally more active in a sulphided form as compared to an oxide form of the catalyst. A sulphiding procedure is used to transform the catalyst from a calcined oxide state to an active sulphided state. Catalyst may be pre-sulphided or sulphided in situ. Because renewable feedstocks generally have a low sulphur content, a sulphiding agent is often added to the feed to maintain the catalyst in a sulphided form.

[0047] As used herein, start-of-run catalytic activity means the activity of the catalyst on a volumetric basis when it is charged to the reactor and after the catalyst is activated, for example, by reduction or sulphiding, and conditioned.

[0048] Preferably, the hydroprocessing catalyst comprises sulphided catalytically active metals. Examples of suitable catalytically active metals include, without limitation, sulphided nickel, sulphided cobalt, sulphided molybdenum, sulphided tungsten, sulphided CoMo, sulphided NiMo, sulphided MoW, sulphided NiW, and combinations thereof. A catalyst bed/zone in the catalyst zone 24 may have a mixture of two types of catalysts and/or successive beds/zones, including stacked beds, and may have the same or different catalysts and/or catalyst mixtures. In case of such sulphided hydroprocessing catalyst, a sulphur source will typically be supplied to the hydroprocessing catalyst to keep the catalyst in sulphided form during the hydroprocessing step.

[0049] The hydrogenation components may be used in bulk metal form or the metals may be supported on a carrier. Suitable carriers include refractory oxides, molecular sieves, and combinations thereof. Examples of suitable refractory oxides include, without limitation, alumina, amorphous silica-alumina, titania, silica, and combinations thereof. Examples of suitable molecular sieves include, without limitation, zeolite Y, zeolite beta, ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48, SAPO-11, SAPO-41, ferrierite, and combinations thereof.

[0050] As mentioned above, the hydroprocessing catalyst may be sulphided in-situ or ex-situ. In-situ sulphiding may be achieved by supplying a sulphur source, usually H.sub.2S or an H.sub.2S precursor (i.e. a compound that easily decomposes into H.sub.2S such as, for example, dimethyl disulphide, di-tert-nonyl polysulphide or di-tert-butyl polysulphide) to the hydroprocessing catalyst during operation of the process. The sulphur source may be supplied with the feed, the hydrogen stream, or separately. An alternative suitable sulphur source is a sulphur-comprising hydrocarbon stream boiling in the diesel or kerosene boiling range that is co-fed with the feedstock. In addition, added sulphur compounds in feed facilitate the control of catalyst stability and may reduce hydrogen consumption.

[0051] Preferably, H.sub.2S is provided to the reactor in an amount in the range of from 50 to 5,000 ppmv, preferably from 100 to 3,000 ppmv, more preferably from 500 to 2,000 ppmv. The amount of H.sub.2S is dependent on a number of factors, including, for example, without limitation, type and amount of catalyst metal, operating temperature, other operating conditions, in the hydrotreating step.

[0052] Operating conditions in the hydroprocessing reactor include pressures in a range of from 1.0 MPa to 20 MPa, temperatures in a range of from 200 to 410? ? C. and liquid hourly space velocities in a range of from 0.3 m.sup.3/m.sup.3.h to 5 m.sup.3/m.sup.3.h based on fresh feed. Preferably, the pressure is selected from a pressure in the range of 2.0 MPa to 15 MPa. Preferably, the temperature is in the range of from 200 to 400? C.

[0053] The ratio of hydrogen to feed supplied in the fixed-bed reactor 12 is in a range of from 200 to 10,000 normal L (at standard conditions of 0? C. and 1 atm (0.101 MPa)) per kg of feed. Reference herein to feed is the total of fresh feedstock excluding any diluent that may be added.

[0054] Embodiments of the filtering zone 30 are illustrated in FIGS. 4A-4B, 5A-5B and 6A-6B. It should be noted that the drawings are not necessarily to scale, for ease of discussion.

[0055] The filtering zone 30 of the present invention has interstitial portions 32 and annular portions 34. The interstitial portions 32 are substantially open to the space above the filtering zone 30. The annular portions 34 are substantially closed to direct downward flow of the feed stream 14. Conversely, the interstitial portions 32 are substantially closed to the headspace 16 above the catalytic zone 18, while the annular portions 34 are in fluid communication with the headspace 16 through openings 36. Advantageously, the openings 36 are formed in a support plate in a manner similar to a conventional catalyst bed support.

[0056] Referring now to FIGS. 4A and 4B, embodiments of configurations of the filtering zone 30 suitable for achieving the method of the present invention are illustrated. It will be understood by those skilled in the art that other shapes and configurations of the interstitial portions 32, annular portions 34, and openings 36 are possible, for practising the process of the present invention.

[0057] The feed stream 14 is directed from the inlet of the fixed-bed reactor 12 to the filtering zone 30, optionally, via a feed distributor (not shown). The feed stream 14 flows to the interstitial portions 32 either directly or by deflecting from a cover 42 at the top of the annular portions 34 (see FIGS. 5A-5B and 6A-6B). The feed stream 14 is then passed from the interstitial portions 32 to the annular portions 34 through a filtering material 38 disposed between the interstitial portions 32 and the annular portions 34.

[0058] The filtering material 38 is preferably a catalytically-inert material or a low-activity catalytic material. Suitable catalytically-inert materials including ceramics, metals, and combinations thereof. An especially suitable ceramic material is alumina. Advantageously, alumina may be formed with a desired porosity for offering even more surface area for capturing fouling and/or particulate matter. The low-activity catalytic material has a start-of-run catalytic activity that is at most 10% of the start-of-run catalytic activity of the catalyst in the catalyst zone 24. For example, in FIG. 4A, the filtering material 38 may be provided as discrete particles (including, without limitation, medallions, rings, spheres, lobes) that are contained between a pair concentric cylinders having perforated or mesh walls. An example of a suitable configuration of this type is illustrated in U.S. Pat. No. 10,562,002B2 (Maas et al., 18 Feb. 2020). Alternatively, the filtering material 38 may be provided as a hollow cylindrical monolith. Cylindrical embodiments of a container or monolith may be replaced with a hexagonal cross-section.

[0059] In the embodiment of FIG. 4B, the filtering material 38 is provided in a rectangular configuration. In one embodiment, discrete particles are contained within a cassette having perforated or mesh walls. In another embodiment, a hollow cuboid monolithic structure is used in the embodiment of FIG. 4B.

[0060] FIGS. 5A and 5B illustrate one embodiment of a cover 42 for each unit of filtering material 38. The cover 42 may be a supported flat cover as illustrated (supports not shown for ease of illustration) or a cap that has a downwardly depending portion. FIGS. 6A and 6B illustrate a cover 42 plate for the sacrificial fouling zone that mimics the bottom support plate but with openings that would preferentially feed the interstitial portions 32 and cover the annular portions 34. The purpose of the cover 42 is to substantially block direct feed flow into the annular portions 34, while allowing flow from the interstitial portions 32 to the annular portions 34 when the fouling and/or particulate matter builds up during operation, as will be explained in more detail below.

[0061] The structure of the filtering zone 30 is configured to provide increased surface area for fouling as compared with a typical catalyst bed in a fixed-bed reactor. For example, a catalyst bed in a 3 m inner diameter reactor would have a cross-sectional area of about 7 m.sup.2. In the embodiment of FIG. 4A, the filtering zone 30 for a 3 m diameter reactor may have 52 cylinders having a diameter of 0.3 m. If, for example, each cylinder is 1 m tall, the available surface area for fouling would be increased to 52 m.sup.2.

[0062] The process of the present invention is illustrated schematically in FIGS. 7A-7C. A feed stream 14 comprising renewable feedstock is introduced in a downward flow into a top portion of a fixed-bed reactor 12. The feed stream 14 is then directed to the interstitial portions 32 of the filtering zone 30 either by flowing directly into the interstitial portions 32 or by redirection caused by cover 42. Initially, as depicted in FIG. 7A, the feed freely flows to the bottom of the interstitial portions 32 and then passes through the filtering material 38 to the annular portions 34 with a liquid level 46. Filtered feed flows through openings 36 to the headspace 16 between the filtering zone 30 and the catalytic zone 18.

[0063] As operation progresses, products of fouling reactions and/or particulate matter produced during injection and/or introduced with the feed 14 are trapped by the voids in the filtering material 38. With time, lower portions of the filtering material 38 are plugged as depicted by the dotted sections 44 of the filtering material 38. In this way, flow of fouling and/or particulate matter to the catalytic zone 18 below is reduced. In addition to becoming trapped in the voids of the filtering material 38, depending on the feed properties. fouling/particulate matter 48 may also build up in the interstitial portions 32, as illustrated in FIG. 7B. Although voids in the lower portions of the filtering material 38 may be plugged to further flow, flow of feed through the upper portions of the filtering material 38 is not impeded and, therefore, an increase in pressure drop is reduced or avoided altogether. As depicted in FIG. 7B, the liquid level 46 rises as voids in the filtering material 38 become plugged with fouling/particulate matter. As the plugged portion 44 of the filtering material 38 is increased, as shown in FIG. 7C, the liquid level 46 further rises and flow through the filtering material 38 is reduced further, until finally, feed preferentially flows through the space between the cover 42 and the filtering material 38. Further fouling and/or particulate matter now passes through the openings 36 to the headspace 16 above the catalytic zone 18.

[0064] In the preferred embodiment of FIG. 2, the catalytic zone 18 has a grading zone 22 above the catalyst zone 24. When the filtered feed 14 passes through the openings 36 to the headspace 16, the filtered feed is then directed to the grading zone 22. The grading zone 22, having a lower start-of-run catalytic activity relative to the catalyst zone 24, causes some hydroprocessing reactions to occur, but at a reduced rate relative to the catalyst zone 24.

[0065] While the catalytic zone 18 may be subjected to fouling once the voids of the filtering material 38 are fully blocked by fouling/particulate matter, the active life of the catalyst in the reactor has increased significantly in accordance with the present invention. By reducing fouling over catalytic zone, the rate of pressure drop build-up is reduced, thereby improving the length of catalyst active life and energy efficiency. Furthermore, operational downtime is significantly reduced in accordance with the present invention.

[0066] While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. For example, one or more image may be performed using one or more of the techniques herein. Various combinations of the techniques provided herein may be used.