Hydrodeoxygenation catalyst loading system

Abstract

A hydrotreatment reactor bed is provided, which comprises – in order – a first layer, a second layer, a third layer and a fourth layer. The BET-surface area, the total pore volume and the pore size di

Description

[0001] HYDRODEOXYGENATION CATALYST LOADING SYSTEM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to purification of hydrocarbon feedstocks, such as a renewable feedstock, or such as a hydrocarbon feedstock co-processing a renewable feedstock with a feedstock originating from a fossil fuel in the production of biofuels.

[0004] BACKGROUND

[0005] Renewable fuels may be produced from a broad variety of sources including animal fats and vegetable oils but also tall oil, pyrolysis oils, hydrothermal liquefaction oils, and other nonedible compounds. Before feedstocks derived from renewable organic material can be used in conventional automobile engines, aviation turbines, marine engines or other engines, and distributed using existing fuel infrastructure, it is desirable to convert the material into hydrocarbons similar to those present in petroleum-derived transportation fuels. One well- established method for this purpose is the conversion of vegetable oils into normal paraffins in the gasoline, jet fuel or diesel boiling range by employing a hydrotreating process.

[0006] In a hydrotreating / hydrotreatment process, the renewable organic material is reacted with hydrogen at elevated temperature and pressure in a catalytic reactor.

[0007] A particular problem with a number of feedstocks such as renewable feedstocks is that they contain impurities such as phosphorus-containing and / or silicon-containing species. Phosphorus- containing species may take the form of phospholipids such as lecithin, from seed oils. Waste (spent) lube oils can also contain species such as zinc dialkyl dithio phosphates (ZDDP), which acts as an anti-wear additive in such lubricants. Phosphorus (P) quickly deactivates conventional catalysts for hydrotreating and reduces their cycle length dramatically. The refiners processing renewable feedstocks are forced to load more material for guarding the hydrotreating catalyst compared to fossil fuel-based refining processes. The units often employ pre-treatment of the feedstocks using washing and / or adsorbents to reduce P from above 10-20 ppm down to 1-2 ppm, but even at 1-2 ppm, guard materials are needed. It is predicted that the renewable fuels market will be moving towards processing more difficult feedstocks (i.e. , tallow, biomass, plastic e.g. waste rich in plastic) that contain higher level of impurities, i.e. contaminants, such as phosphorus and / or silicon. Additionally, it is predicted that existing ultra-low sulfur diesel (LILSD) plants will be converted into renewable units across the Ell and US, however they will have to operate at lower pressures when compared to traditional renewable plants. Finally, refiners are continuously interested in increasing cycle length of processing renewables. All this leads to the future increased demand for the catalysts that are more stable against impurities, in particular phosphorus (P), silicon (Si) and against coking, so they can operate longer life cycles.

[0008] It is therefore vital to reduce, or - if possible - remove impurities, particularly phosphorus- containing species and / or silicon-containing species before reaching the bulk catalyst.

[0009] It is an object of embodiments of the present invention to provide a hydrotreatment reactor bed with improved removal of impurities, in particular phosphorous and / or silicon-containing species. It is a further object of the present invention to provide a hydrotreatment reactor with high capacity for capturing impurities, particularly P and / or Si, in a feedstock originating from a renewable source, or a feedstock combining a renewable source and a fossil fuel. It is another object of embodiments of the present invention to provide a hydrotreatment reactor bed and material for such bed with improved removal of impurities, in particular phosphorous and / or silicon-containing species, while at the same time reducing coking and increasing overall hydrodeoxygenation (HDO) activity of the hydrotreatment reactor bed and thus a hydrotreatment reactor comprising such bed. These and other objects are solved by the present invention.

[0010] Known technology in this area is published in W02022 / 008508, US 9,447,334, US 2004 / 077737, US 4,510,092 and US 4,587,012.

[0011] SUMMARY

[0012] As recited above, it is an object of the present invention to provide a material comprising one or more metals with hydrotreating activity that is capable of capturing impurities, particularly P and / or Si, in hydrocarbon feedstocks, and which minimize coking during operation. Furthermore, the lifecycle of a reactor can be prolonged by incorporating P-guarding function in the whole HDO reactor bed and not only the top (guard) layer. This also reduces said coking - another factor for premature HDO shutdowns due to optimized (reduced) surface areas of HDO catalysts.

[0013] It has been discovered that a prolonged life cycle for HDO reactor beds and processes can be achieved, and a phosphorus guarding function can be introduced along the HDO reactor bed by tuning the textural properties of HDO catalysts (e.g. surface area, pore size and pore size distribution). Additionally, surface area for the HDO catalysts is tailored to be lower in the upper layers and higher in the bottom layers of the HDO reactor bed, which ensures reduced coking along the whole bed. At the same time, higher surface area in the bottom layers ensures that enough active metals can be loaded to ensure sufficient activity in the bottom part of the reactor. Last but not least, it has also been discovered that there is a competitive nature in terms of P and Si removal, so that a significant removal capacity of Si is also achieved, particularly after removal of P.

[0014] So, in a first aspect the present invention relates to a hydrotreatment reactor bed, said reactor bed comprising:

[0015] - a first layer of a first carrier material comprising a first catalyst material, e.g. impregnated with a first catalyst material,

[0016] - a second layer of a second carrier material comprising a second catalyst material, e.g. impregnated with a second catalyst material;

[0017] - a third layer of a third carrier material comprising a third catalyst material, e.g. impregnated with a third catalyst material; and

[0018] - a fourth layer of a fourth carrier material comprising a fourth catalyst material, e.g. impregnated with a fourth catalyst material, said first, second, third and fourth layers being arranged in sequential order in said reactor bed, wherein said first carrier material comprises alumina, said alumina comprising alpha-alumina, suitably said alumina is gamma-alumina free, said first carrier material having a BET-surface area of 1-110 m2 / g, - the first carrier material having a total pore volume of 0.50-0.80 mL / g, such as 0.50- 0.75 mL / g, or 0.55-0.70 mL / g, or 0.60-0.70 mL / g, as measured by mercury intrusion porosimetry, and

[0019] - the first carrier material having a pore size distribution (PSD) with at least 30 vol% of the total pore volume, such as at least 40 vol%, at least 50 vol%, or at least 60 vol% being in pores with a radius > 400 A suitably in pores with a radius > 500 A, such as pores with a radius up to 5000 A;

[0020] - wherein said first catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, and wherein said second carrier material comprises alumina,

[0021] - said alumina comprising any of gamma, kappa, theta-alumina, and combinations thereof, suitably said alumina is: kappa-alumina free and / or alpha-alumina free,

[0022] - said second carrier material having a BET-surface area of 50-170 m2 / g, preferably 80-120 m2 / g, or 150-160 m2 / g,

[0023] - the second carrier material having a total pore volume of 0.70-1.0 mL / g, such as 0.75-0.95 mL / g, as measured by mercury intrusion porosimetry, and

[0024] - the second carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A;

[0025] - wherein said second catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, and wherein the loading of the second catalyst material on the second carrier material is higher than the loading of the first catalyst material on the first carrier material; and wherein said third carrier material comprises alumina,

[0026] - said alumina comprising gamma-alumina, suitably said alumina is: kappa-alumina fee and / or alpha-alumina free,

[0027] - said third carrier material having a BET-surface area of 100-200 m2 / g, preferably 140-180 m2 / g,

[0028] - the third carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry, and

[0029] - the third carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A; - said third catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, wherein the loading of the third catalyst material on the third carrier material is higher than the loading of the second catalyst material on the second carrier material; and wherein said fourth carrier material comprises alumina,

[0030] - said alumina comprising gamma-alumina, suitably said alumina is: kappa-alumina free and / or alpha-alumina free,

[0031] - said fourth carrier material having a BET-surface area of 150-300 m2 / g, preferably 200-260 m2 / g,

[0032] - the fourth carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry,

[0033] - wherein said fourth catalyst material comprises one or more metals selected from Mo, W, and combinations thereof,

[0034] - and wherein said fourth layer comprises a promoter for said fourth catalyst material, said promoter being selected from Ni, Co, and combinations thereof.

[0035] A hydrotreatment reactor comprising the hydrotreatment reactor bed, and a process for removing one or more impurities from a hydrocarbon feedstock, are also provided. Further details of the reactor bed, hydrotreatment reactor and process, are specified in the following detailed description, figures and claims.

[0036] For the purposes of the present application:

[0037] - the term “present invention” or “invention” may be used interchangeably with, respectively, the term “present application” or application; mercury intrusion porosimetry is conducted according to ASTM D4284;

[0038] - BET-surface area is measured according to ASTM D4567-19, i.e. single-point determination of surface area by the BET equation;

[0039] - XRD (X-Ray Diffraction) is conducted according to a standard XRD analysis, in which powder X-ray diffraction patterns are collected on an XPertPro instrument configured in Bragg-Brentano mode using CuK-alpha radiation, and Rietveld analysis using the TOPAS software is used to quantify the phase composition. XRD is used to determine the content of various phases of alumina, e.g. alpha-alumina, thetaalumina or gamma-alumina;

[0040] - the conjunction(s) “and / or” in connection with a feature or embodiment means at least one of the three possible embodiments; for instance, P and / or Si means at least one of P and Si, thus including: P, Si, as well as P and Si;

[0041] - the article “a” or “an” in connection with a feature or embodiment means “at least one”;

[0042] - the term “layers being arranged in sequential order” means that the layers are organized sequentially thus in numerical order, for instance in adjacent order as shown in appended Fig. 1 ;

[0043] - the term “adjacent” means such that one layer starts where the next layer ends;

[0044] - the term “loading” means the content of the metal in the catalyst including the carrier material, as expressed as a weight percentage; for instance, a catalyst with a Mo loading of 5 wt%, means that 5% of the total weight of the catalyst including the carrier material is Mo; the Mo is for instance impregnated and penetrates the pores of the carrier material;

[0045] - the term “comprises” includes “comprises only” i.e. consists of; for instance, a first or second or third catalyst material comprises only Mo; for instance, the fourth catalyst material comprises only NiMo or CoMo;

[0046] - the term “suitably” means “optionally”, i.e. an optional embodiment;

[0047] - the term “hydrocarbon feed” may be used interchangeably with “hydrocarbon feedstock”;

[0048] - individual values of different ranges may be combined; for instance, a BET-surface area of 50-170 m2 / g, preferably 80-120 m2 / g or 150-160 m2 / g, includes ranges such as 50-80 m2 / g, or 50-120 m2 / g, or 50-160 m2 / g, or 80-150 m2 / g, or 80-160 m2 / g; for instance, a total pore volume of 0.70-1.0 mL / g, such as 0.75-0.95 mL / g, includes a range such as 0.70-0.95 mL / g.

[0049] - Other definitions are provided in connection with one or more of above or below embodiments.

[0050] A hydrotreatment reactor bed is provided comprising: a first layer of a first carrier material comprising a first catalyst material, e.g. impregnated with a first catalyst material, - a second layer of a second carrier material comprising a second catalyst material, e.g. impregnated with a second catalyst material;

[0051] - a third layer of a third carrier material comprising a third catalyst material, e.g. impregnated with a third catalyst material; and

[0052] - a fourth layer of a fourth carrier material comprising a fourth catalyst material, e.g. impregnated with a fourth catalyst material, said first, second, third and fourth layers being arranged in sequential order in said reactor bed.

[0053] Fluid introduced at one end of the reactor bed can therefore pass through first, second, third and fourth layers in sequential order.

[0054] In an embodiment, the first, second, third and fourth layers are arranged adjacent one another, in said sequential order, in said reactor bed, such that one layer starts where the next layer ends.

[0055] In an alternative, one or more additional layers, so-called “dummy layers”, may be present between any or all of said first, second, third or fourth layers. “Dummy layers” may comprise carrier material, but typically no catalyst material. All layers in the reactor bed typically have the same cross-section of about 2 to 3 m, such as 2.0-2.5 m.

[0056] In an embodiment, any of said first, second and third carrier material is absent of a promoter or contains up to 0.2 wt% promoter, such as up to 0.1 wt% promoter,. For the purposes of the present application, Mo, W or combinations thereof in any of the carrier materials is regarded as a first metal, while the promoter is regarded as a second metal. The promoter is selected from Ni, Co, and combinations thereof. The invention enables therefore to provide a gradient bed approach for coping with the problems of removing particularly P and / or Si not only through a first (top) layer, but advantageously also across a plurality of layers, particularly across the entire reactor bed length and thus across all four layers of the reactor bed, while at the same time increasing overall HDO activity as well as reducing coking, thereby also increasing catalyst cycle length and enabling longer operation of the reactor bed.

[0057] The invention enables that P associated with some hydrocarbon feeds such as renewable feeds is mainly removed in the first layer of the reactor bed, while more stable P associated with other hydrocarbon feeds such as pyrolysis oils or hydrothermal liquefaction oils or spent lube oils is removed along the lower layers of the reactor bed, along with Si. The invention provides therefore high flexibility in the handling of hydrocarbon feeds. Si and especially P react in very different ways with the grading and to some extent compete for the available surface area of the carrier material. Depending on the hydrocarbon feedstock there may be a different loading regarding carrier properties. Applicant has found that P forms a crust on the catalyst and needs special grading in many renewable hydrocarbon feedstocks, while plastic pyrolysis oil (PPO) or hydrothermal liquefaction oils, as well as e.g. spent lube oil, allow for deep penetration of P. In combination, Si is also captured and can compete with P. Hence, with respect to P and / or Si impurities, their removal is not simply a matter of providing a discrete layer on top of the hydrotreatment reactor, i.e. with the top layer therein acting as a guard bed, for removing P. Since impurities may also comprise Si, for which the mechanism for its removal acts in opposite direction to P-removal, their removal poses a significant challenge. Along the reactor bed, P is mainly removed in the first layer with lower removal in the subsequent second to fourth layers, while Si is at most slightly removed in in the first layer with a higher removal in the subsequent second to fourth layers. Again, the invention enables the removal of P and / or Si regardless of the type or hydrocarbon feed, thus regardless of how stable the associated impurity, e.g. P, is in such feed.

[0058] It has also been found that the lower the surface area the lower the coking, and the higher the P-capture capacity. Further, the higher the surface area, the higher the Si-capture capacity and hydrotreating (HDO) activity due to the tailoring of the metal loading.

[0059] The first carrier material comprises alumina,

[0060] - said alumina comprising alpha-alumina,

[0061] - said first carrier material having a BET-surface area of 1-110 m2 / g,

[0062] - the first carrier material having a total pore volume of 0.50-0.80 mL / g, such as 0.50- 0.75 mL / g, or 0.55-0.70 mL / g, or 0.60-0.70 mL / g, as measured by mercury intrusion porosimetry, and

[0063] - the first carrier material having a pore size distribution (PSD) with at least 30 vol% of the total pore volume, such as at least 40 vol%, at least 50 vol%, or at least 60 vol% being in pores with a radius > 400 A suitably in pores with a radius > 500 A, such as pores with a radius up to 5000 A; wherein said first catalyst material comprises one or more metals selected from Mo, W, and combinations thereof.

[0064] In an embodiment, up to 60 vol% of the total pore volume of the first carrier material such as up to 40 vol% of the total pore volume being in pores with a radius below 400 A, such as pores with a radius down to 40 A, or down to 80 A.

[0065] While the bigger pores with radius equal to or above 400 A, or equal to or above 500 A, serve for P-capture, the smaller pores with radius below 400 A enable better use of the one or more metals in the porous material for providing hydrotreating activity. The porous material may for instance show a broad peak as a unimodal pore system or show a bimodal or even trimodal pore system, in which particularly the smaller pores add the possibility for providing the hydrotreating activity to the porous material.

[0066] In one embodiment, the BET-surface area of the carrier material in the first layer is 1-70 m2 / g, such as 1-60 m2 / g, or 1-30 m2 / g such as 10-30 m2 / g e.g. 15-25 m2 / g. Suitably, the BET-surface area is any of 5, 10, 15, 20, 25, 30, 35, 40, 45, 60, 65 m2 / g.

[0067] In an embodiment, the first catalyst material comprises said one or more metals with a loading of 1-5 wt%. In an embodiment, the first catalyst material comprises only the metal Mo with a loading of 1-5% (1-5 wt%). In an embodiment, the first catalyst material comprises the metal Mo as a first metal and a promoter as a second metal, the promoter content being up to 0.2 wt%, such as up to 0.1 wt%, the promoter being selected from Ni, Co, and combinations thereof.

[0068] Suitably, the carrier material in layer 10 corresponds to applicant’s W02022 / 008508 - Table 1 Sample 2.

[0069] In an embodiment, the BET-surface area of the first carrier material is greater than that of the second carrier material; and / or the total pore volume of the first carrier material is greater than that of the second carrier material. Significant penetration of P into the carrier material is thereby achieved already in the first layer, thus providing advantageous conditions for Si removal in subsequent beds. Si removal has been found to increase after first removing P, as P appears to block the pores thus impeding Si penetration. Further, it has been found that Si removal is enhanced at higher temperatures, and since the temperature increases along the reactor bed length, the second layer having a higher temperature than the first layer further enables the Si removal.

[0070] In an embodiment, the loading of catalyst material on the carrier material increases from first to second, and second to third layers, and - optionally - also from third to fourth layers.

[0071] The second carrier material comprises alumina,

[0072] - said alumina comprising any of gamma-alumina, theta-alumina, kappa-alumina, and combinations thereof, suitably the alumina is alpha-alumina free,

[0073] - said second carrier material having a BET-surface area of 50-170 m2 / g, preferably 80-120 m2 / g or 150-160 m2 / g,

[0074] - the second carrier material having a total pore volume of 0.70-1.0 mL / g, such as 0.75-0.95 mL / g, as measured by mercury intrusion porosimetry, and

[0075] - the second carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A;

[0076] - wherein said second catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, and wherein the loading of the second catalyst material on the second carrier material is higher than the loading of the first catalyst material on the first carrier material.

[0077] In an embodiment, the second catalyst material comprises said one or more metals with a loading of 5-10 wt%. In an embodiment, the second catalyst material comprises only Mo with a loading of 5-10 wt%. In an embodiment, the second catalyst material comprises the metal Mo as a first metal and a promoter as a second metal, the promoter content being up to 0.2 wt%, such as up to 0.1 wt%, the promoter being selected from Ni, Co, and combinations thereof. For instance, the first catalyst material comprises only Mo with a loading of 2 wt%, and the second catalyst material comprises only Mo with a loading of 5 wt%.

[0078] The third carrier material comprises alumina,

[0079] - said alumina comprising gamma-alumina, suitably said alumina is alpha-alumina free,

[0080] - said third carrier material having a BET-surface area of 100-200 m2 / g, preferably 140-180 m2 / g, - the third carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry, and

[0081] - the third carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A;

[0082] - said third catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, wherein the loading of the third catalyst material on the third carrier material is higher than the loading of the second catalyst material on the second carrier material.

[0083] In an embodiment, the third catalyst material comprises said one or more metals with a loading of 8-15 wt%. In an embodiment, the third catalyst material comprises only Mo with a loading of 8-15 wt%. In an embodiment, the second catalyst material comprises the metal Mo as a first metal and a promoter as a second metal, the promoter content being up to 0.2 wt%, such as up to 0.1 wt%, the promoter being selected from Ni, Co, and combinations thereof. For instance, the second catalyst material comprises only Mo with a loading of 5 wt%, and the third catalyst material comprises only Mo with a loading of 8 wt%.

[0084] The fourth carrier material comprises alumina,

[0085] - said alumina comprising gamma-alumina, suitably said alumina is alpha-alumina free,

[0086] - said fourth carrier material having a BET-surface area of 150-300 m2 / g, preferably 200-260 m2 / g,

[0087] - the fourth carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry,

[0088] - wherein said fourth catalyst material comprises one or more metals selected from Mo, W, and combinations thereof,

[0089] - and wherein said fourth layer comprises a promoter for said fourth catalyst material, said promoter being selected from Ni, Co, and combinations thereof.

[0090] The one or more metals selected from Mo, W, and combinations thereof represent a first metal in the fourth carrier material. The promoter in the fourth layer may be Co or Ni. Co or Ni represent a second metal in the fourth carrier material. By using said promoter(s), e.g. here for the first time in the fourth catalyst material, it is possible to increase the overall hydrodeoxygenation (HDO) activity of the reactor bed. By the invention, the use of the promoter, e.g. Ni, is counterintuitively only provided in the fourth layer to provide a significant increase in HDO activity i.e. deoxygenation, despite this being at the expense of selectivity, as the provision of the promoter may also increase hydrogenation activity by decarboxylation rather than the desired hydrodexoygenation.

[0091] In an embodiment, the fourth catalyst material comprises said one or more metals, suitably only Mo, together with a promoter, suitably only Ni, with a combined loading of 10-20 wt%. In an embodiment, the content of the promoter, e.g. Ni, in the fourth catalyst material is 0.5-3 wt%. In an embodiment, the fourth catalyst material comprises only NiMo with a loading i.e. combined loading, of 10-20 wt%. For instance, in the fourth catalyst material of the fourth layer the Mo-loading is 3 wt% and the combined loading of NiMo is 15 wt%.

[0092] Accordingly, in an embodiment which compiles the above recited loadings, the first catalyst material comprises said one or more metals, suitably only Mo, with a loading of 1-5 wt%; the second catalyst material comprises said one or more metals, suitably only Mo, with a loading of 5-10 wt%; the third catalyst material comprises said one or more metals, suitably only Mo, with a loading of 8-15 wt%; the fourth catalyst material comprises said one or more metals, suitably only Mo, together with a promoter suitably only Ni, with a combined loading of 10-20 wt%.

[0093] In an embodiment, the carrier material in each of said first, second, third or fourth layers, may further comprise any of titania (TiCh), silica (SiCh), magnesium-aluminium spinel (MgAhOt), and combinations thereof. For instance, any of these may substitute some of the alumina used in any of the first, second, third or fourth carrier materials.

[0094] In an embodiment, the content of alpha-alumina in said first carrier materials is 90-100 wt% as determined by XRD.

[0095] In an embodiment, the content of gamma, kappa and theta- alumina in said second carrier material is 90-100 wt% as determined by XRD. Suitably, the alumina of the second carrier material comprises gamma and theta-alumina with no alpha-alumina (hence alpha-alumina free), and the content of the gamma and theta-alumina in said second carrier material is 90- 100 wt%.

[0096] In an embodiment of the invention, the content of gamma-alumina in each of said third or fourth carrier materials is 90-100 wt% as determined by XRD. In an embodiment, the content of gamma-alumina in said first carrier materials is 0 wt%, i.e. the porous material is gamma-alumina free i.e. free of gamma-alumina.

[0097] In an embodiment, the content of alpha-alumina in any of said second, third or fourth carrier material is 0 wt%, i.e. the porous material is alpha-alumina free i.e. free of alpha-alumina.

[0098] Accordingly, in an embodiment which encompasses the above alumina contents, the content of alpha-alumina in said first carrier material is 90-100 wt%; and / or wherein the content of gamma-alumina, kappa-alumina and theta-alumina in said second carrier material is 90-100 wt%; and / or wherein the content of gamma-alumina in said third and fourth carrier material is 90-100 wt%.

[0099] The carrier material in each of said first, second, third or fourth layers, may further comprise a compound selected from Al-borates, calcium aluminates, silicon aluminates, and combinations thereof.

[0100] In an embodiment, the carrier material in each of said first, second, third or fourth layers is an extruded or tabletized pellet having a shape selected from trilobal, tetralobal, pentalobal, cylindrical, spherical, hollow such as hollow rings or hollow cylinders, and combinations thereof. Preferably the carrier material in each of said first, second, third or fourth layers is an extruded or tabletized pellet, having a different shape in adjacent layers.

[0101] The present technology also provides a hydrotreatment reactor comprising the hydrotreatment reactor bed as defined herein, arranged within a reactor vessel, wherein the reactor bed is arranged inside the reactor vessel such that a feedstock inlet to the reactor vessel passes through the first, second, third and fourth layers sequentially.

[0102] In an embodiment, the reactor vessel is substantially cylindrical with first and second opposing ends, wherein the reactor vessel comprises an inlet for a hydrocarbon feedstock located at or adjacent to the first end of the reactor vessel, and wherein the first, second, third and fourth layers are arranged sequentially with the first layer located closest to the inlet.

[0103] In an embodiment, the hydrotreatment reactor comprises a plurality of reactor beds as defined above. The hydrotreatment reactor may thus also comprise a plurality of feedstock inlets, each one corresponding to a reactor bed. For instance, the hydrotreatment reactor comprises a first inlet for a first hydrocarbon feedstock inlet, i.e. a first hydrocarbon feedstock inlet, corresponding to a first reactor bed; and a second inlet for a second hydrocarbon feedstock corresponding to a second reactor bed arranged downstream. Additional hydrocarbon feedstock inlets and corresponding reactor beds may be provided, such a third inlet for a third feedstock inlet corresponding to a third reactor bed arranged downstream.

[0104] The hydrotreatment reactor comprises an outlet, such as a common outlet, for withdrawing the hydrotreatment reactor effluent.

[0105] Suitably, the hydrotreatment reactor is arranged to provide a temperature of the first reactor bed which is lower than the second reactor bed arranged downstream. Suitably, the hydrotreatment reactor is arranged to provide a temperature of the second reactor bed which is lower than the third reactor bed arranged downstream.

[0106] Suitably, the hydrotreatment reactor is arranged to operate as an adiabatic fixed bed reactor. Hence, there is an adiabatic temperature increase in each reactor bed. As used herein, the temperature is the inlet temperature at a respective reactor bed of the hydrotreatment reactor. The inlet temperature of the first reactor bed is for instance 275°C, the inlet temperature of the second reactor bed is for instance 325°C.

[0107] A process for removing one or more impurities from a hydrocarbon feedstock is also provided. The process comprises the step of passing said hydrocarbon feedstock through said hydrotreatment reactor as defined herein, such that the hydrocarbon feedstock passes through in each of said first, second, third and fourth layers in turn wherein the one or more impurities are selected from a vanadium-containing impurity, silicon-containing impurity, a halide-containing impurity, an iron-containing impurity, a phosphorous-containing impurity, and combinations thereof; preferably a phosphorous (P) and / or silicon (Si)-containing impurity.

[0108] In an embodiment, the process is carried out at high temperature such as 100-400°C, optionally in the presence of a reducing agent such as hydrogen.

[0109] In an embodiment, the hydrocarbon feedstock is: i) a renewable source obtained from a raw material of renewable origin, such as originating from plants, algae, animals, fish, vegetable oil refining, domestic waste, waste rich in plastic, sewage sludge, industrial organic waste like tall oil or black liquor, or a feedstock derived from one or more oxygenates taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes and alcohols where said oxygenates originate from one or more of a biological source, a gasification process, a pyrolysis process, or hydrothermal liquefaction (HTL) process, Fischer-Tropsch synthesis, and methanol based synthesis; or ii) a feedstock originating from a fossil fuel, such as diesel, kerosene, naphtha, vacuum gas oil (VGO), spent lube oil, or combinations thereof; or iii) a feedstock originating from combining a renewable source according to i) and a feedstock originating from a fossil fuel according to ii).

[0110] In an embodiment, the portion of the hydrocarbon feedstock originating from a renewable source is suitably 5-60 wt%, such as 10 or 50 wt%.

[0111] For instance, the term “pyrolysis process, or hydrothermal liquefaction (HTL) process” shall for convenience be used broadly for a decomposition process, both in the presence and absence of a catalyst, in which a material is partially decomposed at elevated temperature (typically 250°C to 800°C or even 1000°C), in the presence of substoichiometric amount of oxygen (including no oxygen). The product will typically be a combined liquid and gaseous stream, as well as an amount of solid char.

[0112] Accordingly, in an embodiment, the pyrolysis process is fast pyrolysis, as defined farther below, thereby producing a pyrolysis oil stream as hydrocarbon feedstock.

[0113] For the purposes of the present invention, the pyrolysis section generates two main streams, namely a pyrolysis off-gas stream and a pyrolysis oil stream. The pyrolysis section may be in the form of a fluidized bed, transported bed, or circulating fluid bed, as is well known in the art. For instance, the pyrolysis section may comprise a pyrolyser unit (pyrolysis reactor), cyclone(s) to remove particulate solids such as char, and a cooling unit for thereby producing said pyrolysis off-gas stream and said pyrolysis oil stream, i.e. condensed pyrolysis oil. The pyrolysis off-gas stream comprises light hydrocarbons e.g. C1-C4 hydrocarbons, CO and CO2. The pyrolysis oil stream is also referred as bio-oil and is a liquid substance rich in blends of molecules usually consisting of more than two hundred different compounds including aldehydes, ketones and / or other compounds such as furfural having a carbonyl group, resulting from the depolymerisation of products treated in pyrolysis.

[0114] For the purposes of the present invention, the pyrolysis is preferably fast pyrolysis, also referred in the art as flash pyrolysis. Fast pyrolysis means the thermal decomposition of a solid renewable feedstock in the absence of oxygen, at temperatures in the range 350- 650°C e.g. about 500°C and reaction times of 10 seconds or less, such as 5 seconds or less, e.g. about 2 sec. Fast pyrolysis may for instance be conducted by autothermal operation e.g. in a fluidized bed reactor. The latter is also referred as autothermal pyrolysis and is characterized by employing air, optionally with an inert gas or recycle gas, as the fluidizing gas, or by using a mixture of air and inert gas or recycle gas. Thereby, the partial oxidation of pyrolysis compounds being produced in the pyrolysis reactor (autothermal reactor) provides the energy for pyrolysis while at the same time improving heat transfer. For details about autothermal pyrolysis, reference is given to e.g “Heterodoxy in Fast Pyrolysis of Biomass” by Robert Brown: https: / / dx.doi.Org / 10.1021 / acs. energyfuels.0c03512

[0115] It is therefore be understood, that for the purposes of the present invention, the use of autothermal pyrolysis, i.e. autothermal operation, is a particular embodiment for conducting fast pyrolysis.

[0116] There are several types of fast pyrolysis where a catalyst is used. Sometimes an acid catalyst is used in the pyrolysis reactor to upgrade the pyrolysis vapors, this technology is called catalytic fast pyrolysis and can both be operated in an in-situ mode (the catalyst is located in the pyrolysis reactor) and an ex-situ mode (the catalyst is placed in a separate reactor). The use of a catalyst conveys the advantage of lowering the activation energy for reactions thereby significantly reducing the required temperature for conducting the pyrolysis. In addition, increased selectivity towards desired pyrolysis oil compounds may be achieved.

[0117] In some cases, hydrogen is added to the catalytic pyrolysis which is called reactive catalytic fast pyrolysis. If the catalytic pyrolysis is conducted at a high hydrogen pressure (~>5 barg) it is often called catalytic hydropyrolysis.

[0118] In an embodiment, the pyrolysis stage is fast pyrolysis which is conducted without the presence of a catalyst and hydrogen, i.e. the fast pyrolysis stage is not catalytic fast pyrolysis, hydropyrolysis or catalytic hydropyrolysis. This enables a much simpler and inexpensive process. In another embodiment, a hydrothermal liquefaction process is provided, thereby producing a hydrothermally liquified oil stream as hydrocarbon feedstock.

[0119] Hydrothermal liquefaction means the thermochemical conversion of biomass into liquid fuels by processing in a hot, pressurized water environment for sufficient time to break down the solid bio-polymeric structure to mainly liquid components. Typical hydrothermal processing conditions are temperatures in the range of 250-375°C and operating pressures in the range of 40-220 bar. This technology offers the advantage of operation of a lower temperature, higher energy efficiency and lower tar yield compared to pyrolysis, e.g. fast pyrolysis. For details on hydrothermal liquefaction of biomass, reference is given to e.g. Golakota et al., “A review of hydrothermal liquefaction of biomass”, Renewable and Sustainable Energy Reviews, vol. 81 , Part 1, Jan. 2018, p. 1378-1392.

[0120] In an embodiment, the one or more impurities is a phosphorous (P)-containing impurity and / or a silicon (Si)-containing impurity; said hydrocarbon feedstock contains 0.5-1000 ppm P and / or 0.5-500 ppm Si. For instance, a waste rich in plastic has a Si content in the range 5-250 ppm. For instance, for a tall oil has a Si content is 0.5-5 ppm.

[0121] BRIEF DESCRIPTION OF THE DRAWINGS

[0122] Fig. 1 shows a schematic drawing of hydrotreatment reactor 100 comprising a reactor bed 200 in accordance with an embodiment of the invention.

[0123] Fig. 2 shows a scheme of first 10, second 20, third 30 and fourth 40 layers of the reactor bed 200 providing a gradient approach with the associated increase in activity as well as decrease in HDO selectivity and P-guard (i.e. P-capture) ability along the reactor bed length from inlet to outlet of the reactor bed 200.

[0124] Fig. 3 shows the penetration and thus removal of impurities P and Si in the first (top) layer 10, corresponding to carrier material of applicant’s W02022 / 008508 - Table 1 Sample 2. The Y-axis in the lower portion of the figure represents approximate relative concentrations of the different species.

[0125] Fig. 4 shows the penetration and thus removal of the impurities P and Si in the second 20 and third 30 layers, at lower temperature (second layer 20, upper portion) and higher temperature (third layer 30, lower portion) when treating tall oil as renewable fed. The Y-axis represents approximate relative concentrations of the different species.

[0126] Fig. 5 shows, for comparison, the competition between P and Si removal when treating lube oil as hydrocarbon feed in a single layer combining second 20 and third 30 layers, which is according to the prior art i.e. current system. The Y-axis represents approximate relative concentrations of the different species.

[0127] Fig. 6 shows the penetration and thus removal of the impurity Si in a fourth layer 40 when P has been removed prior when treating spent lube oil. The Y-axis represents approximate relative concentrations of the different species.

[0128] Fig. 7 shows, for comparison, the competition between P and Si removal when treating spent lube oil in the fourth layer 40 layer. The Y-axis represents approximate relative concentrations of the different species.

[0129] EXAMPLES

[0130] Experimental runs were conducted in a hydrotreatment reactor 100 with a gradient approach as shown in Fig. 1 , with the following carrier materials in layers 10, 20, 30, 40 of reactor bed 200.

[0131] Layer 10: As in applicant’s W02022008508 Table 1 - Sample 2, thus BET: 9-10 m2 / g; total PV: 0.6 mL / g; pore size distribution PSD: 99% total pore volume above 400A radius.

[0132] Alumina: 90 wt% alpha-alumina, 10 wt% theta-alumina.

[0133] Layer 20: BET: 50-170 m2 / g, specifically here 150 m2 / g; total PV: 0.7-1.0 mL / g, specifically here 900 mL / g; pore size distribution PSD: 20 - 40% total pore volume above 250A radius, specifically here 25% above 250A radius. Alumina: 100 wt% gamma-alumina.

[0134] Layer 30: BET: 100-200 m2 / g, specifically here 150 m2 / g; total PV: 0.8- 1.2 mL / g, specifically here 1000 mL / g; pore size distribution PSD: 20-40% total pore volume above 250A radius, specifically here 25% above 250A radius. Alumina: 100 wt% gamma-alumina. Layer 40: BET: 150 - 300 m2 / g, specifically here 240 m2 / g; total PV: 0.8-1.2 mL / g, specifically here 890 mL / g; pore size distribution PSD: no limitation. Alumina: 100 wt% gamma.

[0135] Fig. 1 shows a schematic drawing of hydrotreatment reactor 100, with a reactor vessel 300 which is substantially cylindrical with first 301 and second 302 opposing ends, and in which the reactor vessel 300 comprises an inlet 303 for a hydrocarbon feedstock located at or adjacent to the first end 301 of the reactor vessel 300, and in which the first 10, second 20, third 30 and fourth 40 layers are arranged sequentially with the first layer located closest to the inlet 303. An outlet 304 for the effluent of the reactor bed 200 is also illustrated. It is understood that a plurality of additional reactor beds may be arranged downstream reactor bed 200, with associated inlet for a hydrocarbon feedstock.

[0136] Fig. 2 shows the observed trend of HDO activity gradient as well as the HDO selectivity and P-guard (P-capture) ability. The HDO activity is advantageously increased along the reactor bed from first 10 layer through fourth 40 layer, despite this being at the expense of HDO selectivity in the lower layer 40. This is achieved by having Mo in layers 10, 20 and 30 with increased Mo load, while having NiMo in layer 40, i.e. including the promotor Ni in layer 40. The content of Mo is gradually increased from about 1-5 wt% in layer 10 to layer 40, thus in layer 10 the Mo-loading is 1-5 wt%, in layer 20 the Mo-loading is 5-10 wt%, in layer 30 the Mo-loading is 8-15 wt%, and in layer 40 the combined NiMo-loading of 10-20 wt%. Addition of the promoter Ni increases activity dramatically but lowers selectivity. Ni is provided in the lower layer 40.

[0137] Fig. 3 shows the penetration and thus removal of P and Si in the first (top) layer 10 when treating tall oil as renewable feed. The curves in the bottom picture are from a line-scan across the extrudate, here a tetralobal shaped particle. Rather than P only forming a thin outer layer, thus providing a very low P-penetration and attendant low P-capture, and which is the case where a carrier material other than the first carrier material such as the second carrier material is provided as the first layer 10, the carrier material in layer 10 shows a thick outer P-layer of at least 500 micrometres as there is also penetration towards the center of the particle, here having a tetralobal shape, thus providing significant P-penetration. Although to a lesser extent, there is also P present in the center. The corresponding SEM picture on the top of Fig. 3 shows such outer P-layer in the carrier material. Furthermore, it is also observed the competition between P and Si removal: P appears to block pores so that Si achieves an even distribution only when the P-content is low. Fig. 4 shows the P and Si penetration in the carrier material when treating tall oil as renewable feed. A thin P-layer, which blocks access to pores, appears when the temperature is higher (“higher temp”) hence in third layer 30. Hence, there is lower Si in around the center at the higher temperature compared to a more even profile of Si at lower temperature (“lower temp”) hence in the upper second layer 20 as shown in the upper portion of the figure. There is lower penetration of P at the higher temperature. The temperature difference in between these adjacent layers 20 and 30 is about 10°C. The asymmetry in the graphs of Fig. 4 after 2500 micrometres is due to asymmetry of the tetralobal shaped particle.

[0138] Fig. 5 shows the P and Si penetration in the carrier material when treating spent lube oil as hydrocarbon feed in a current system having a single layer, instead of corresponding to layers 20 / 30 according to the present invention. It is observed that, contrary to when treating tall oil, P spreads evenly and strongly competes with Si. The P and Si competition is significant without blocking access to pores.

[0139] Fig 6 shows the P and Si penetration in the carrier material when treating spent lube oil as hydrocarbon feed in the fourth layer 40, with more P being removed, i.e. captured, in the upper layers, thereby allowing for more Si-capture, as Si takes over the vacancies in the pores.

[0140] Fig 7 shows the effect in the fourth layer 40 when P has not been significantly removed in the upper layers. Hence, the difference between Fig. 7 and 6 is the relative amount of P and Si: in Fig. 7 P has been removed while in Fig. 6 P is present. It is observed in Fig. 6 that when P has been removed in the upper layers, Si spreads evenly with high levels of Si- capture. The competition between P and Si removal is again observed in Fig. 7: as P is removed, there is a higher concentration of Si on the inside due to competition with the more reactive P on the outer layer.

[0141] The invention enables therefore to provide a gradient bed approach for coping with the problems of removing P and / or Si not only through a first (top) layer, but across the entire reactor bed length and thus across all four layers 10, 20, 30, 40 of the reactor bed, while at the same time increasing overall HDO activity as well as reducing coking, thereby also increasing catalyst cycle length and enabling longer operation of the reactor bed. The P associated with e.g. a tall oil is mainly removed in the first layer 10 of the reactor bed, while more stable P associated with other hydrocarbon feeds, here specifically spent lube oil, is removed along the lower layers 20, 30, 40 of the reactor bed, along with Si. The invention provides therefore high flexibility in the handling of hydrocarbon feeds. Si and especially P react in very different ways with the grading and to some extent compete for the available surface area of the carrier material, as also shown in Fig. 3-7. It is observed that while P forms a crust and needs special grading in a renewable hydrocarbon feedstock such as tall oil, (spent) lube oil allows for deep penetration of P. In combination, Si is also captured and can compete with P. Along the reactor bed, P is mainly removed in the first layer with lower removal in the subsequent second to fourth layers, while Si is at most slightly removed in in the first layer with a higher removal in the subsequent second to fourth layers. Yet again, the invention enables the removal of P and / or Si regardless of the type or hydrocarbon feedstock, thus regardless of how stable the associated impurity, e.g. any of P and Si, is in such feedstock.

[0142] The technology has been described with reference to a number of embodiments and aspects. The person skilled in the art is capable of combining elements from various embodiments and aspects while remaining within the scope of the present claims. All references mentioned herein are incorporated by reference.

Claims

CLAIMS1. A hydrotreatment reactor bed (200), said reactor bed (200) comprising:- a first layer (10) of a first carrier material comprising a first catalyst material,- a second layer (20) of a second carrier material comprising a second catalyst material;- a third layer (30) of a third carrier material comprising a third catalyst material; and- a fourth layer (40) of a fourth carrier material comprising a fourth catalyst material; said first (10), second (20), third (30) and fourth (40) layers being arranged in sequential order in said reactor bed (200); wherein said first carrier material comprises alumina,- said alumina comprising alpha-alumina,- said first carrier material having a BET-surface area of 1-110 m2 / g,- the first carrier material having a total pore volume of 0.50-0.80 mL / g, such as 0.50- 0.75 mL / g, or 0.55-0.70 mL / g, or 0.60-0.70 mL / g, as measured by mercury intrusion porosimetry, and- the first carrier material having a pore size distribution (PSD) with at least 30 vol% of the total pore volume, such as at least 40 vol%, at least 50 vol%, or at least 60 vol% being in pores with a radius > 400 A suitably in pores with a radius > 500 A, such as pores with a radius up to 5000 A;- wherein said first catalyst material comprises one or more metals selected from Mo, W, and combinations thereof; and wherein said second carrier material comprises alumina,- said alumina comprising any of gamma-alumina, theta-alumina, kappa-alumina, and combinations thereof,- said second carrier material having a BET-surface area of 50-170 m2 / g, preferably 80-120 m2 / g or 150-160 m2 / g,- the second carrier material having a total pore volume of 0.70-1.0 mL / g, such as 0.75-0.95 mL / g, as measured by mercury intrusion porosimetry, and- the second carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A;- wherein said second catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, and wherein the loading of the second catalystmaterial on the second carrier material is higher than the loading of the first catalyst material on the first carrier material; and wherein said third carrier material comprises alumina,- said alumina comprising gamma-alumina,- said third carrier material having a BET-surface area of 100-200 m2 / g, preferably 140-180 m2 / g,- the third carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry, and- the third carrier material having a pore size distribution (PSD) with 20-40 vol% of the total pore volume, being in pores with a radius > 250 A;- said third catalyst material comprises one or more metals selected from Mo, W, and combinations thereof, wherein the loading of the third catalyst material on the third carrier material is higher than the loading of the second catalyst material on the second carrier material; and wherein said fourth carrier material comprises alumina,- said alumina comprising gamma-alumina,- said fourth carrier material having a BET-surface area of 150-300 m2 / g, preferably 200-260 m2 / g,- the fourth carrier material having a total pore volume of 0.80-1.2 mL / g, such as 0.85- 1.1 mL / g, as measured by mercury intrusion porosimetry,- wherein said fourth catalyst material comprises one or more metals selected from Mo, W, and combinations thereof,- and wherein said fourth layer comprises a promoter for said fourth catalyst material, said promoter being selected from Ni, Co, and combinations thereof.

2. The reactor bed (200) according to claim 1, wherein said first (10), second (20), third (30) and fourth (40) layers are arranged adjacent one another, in said sequential order, in said reactor bed (200).

3. The reactor bed (200) according to any one of the preceding claims, wherein up to 60 vol% of the total pore volume of the first carrier material such as up to 40 vol% of the total pore volume being in pores with a radius below 400 A, such as pores with a radius down to 40 A, or down to 80 A.

4. The reactor bed (200) according to any one of the preceding claims, wherein the BET-surface area of the first carrier material is greater than that of the second carrier material; and / or wherein the total pore volume of the first carrier material is greater than that of the second carrier material.

5. The reactor bed (200) according to any of the preceding claims, wherein the loading of catalyst material on the carrier material increases from first to second, and second to third layers, and - optionally - also from third to fourth layers.

6. The reactor bed (200) according to any preceding claims, wherein: the first catalyst material comprises said one or more metals, suitably only Mo, with a loading of 1-5 wt%; the second catalyst material comprises said one or more metals, suitably only Mo, with a loading of 5-10 wt%; the third catalyst material comprises said one or more metals, suitably only Mo, with a loading of 8-15 wt%; the fourth catalyst material comprises said one or more metals, suitably only Mo, together with a promoter, suitably only Ni, with a combined loading of 10-20 wt%.

7. The reactor bed (200) according to any one of the preceding claims, wherein the content of alpha-alumina in said first carrier material is 90-100 wt%; and / or wherein the content of gamma-alumina, kappa-alumina and theta-alumina in said second carrier material is 90-100 wt%; and / or wherein the content of gamma-alumina in said third and fourth carrier material is 90-100 wt%.

8. A hydrotreatment reactor (100) comprising the hydrotreatment reactor bed (200) according to any one of the preceding claims arranged within a reactor vessel (300), wherein said reactor bed (200) being arranged inside the reactor vessel (300) such that a feedstock inlet to the reactor vessel (300) passes through the first (10), second (20), third (30) and fourth (40) layers sequentially.

9. The hydrotreatment reactor (100) according to claim 8, wherein the reactor vessel (300) is substantially cylindrical with first (301) and second (302) opposing ends, wherein the reactor vessel (300) comprises an inlet (303) for a hydrocarbon feedstock located at or adjacent to the first end (301) of the reactor vessel (300), and wherein the first (10), second (20), third (30) and fourth (40) layers are arranged sequentially with the first layer located closest to the inlet (303).

10. A process for removing one or more impurities from a hydrocarbon feedstock, said process comprising the step of passing said hydrocarbon feedstock through said hydrotreatment reactor (100) according to any one the claims 8 or 9, such that the hydrocarbon feedstock passes through in each of said first (10), second (20), third (30) and fourth (40) layers in sequence; wherein the one or more impurities are selected from a vanadium-containing impurity, silicon-containing impurity, a halide-containing impurity, an iron-containing impurity, a phosphorous-containing impurity, and combinations thereof; preferably a phosphorous (P) and / or silicon (Si)-containing impurity.

11. The process according to claim 10, which process is carried out at high temperature such as 100-400°C, optionally in the presence of a reducing agent such as hydrogen.

12. The process according to any one of claims 10-11, wherein the hydrocarbon feedstock is: i) a renewable source obtained from a raw material of renewable origin, such as originating from plants, algae, animals, fish, vegetable oil refining, domestic waste, waste rich in plastic, sewage sludge, industrial organic waste like tall oil or black liquor, or a feedstock derived from one or more oxygenates taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes and alcohols where said oxygenates originate from one or more of a biological source, a gasification process, a pyrolysis process or hydrothermal liquefaction (HTL) process, Fischer-Tropsch synthesis, and methanol based synthesis; or ii) a feedstock originating from a fossil fuel, such as diesel, kerosene, naphtha, vacuum gas oil (VGO), spent lube oil, or combinations thereof; or iii) a feedstock originating from combining a renewable source according to i) and a feedstock originating from a fossil fuel according to ii).

13. The process according to claim 12, wherein the portion of the hydrocarbon feedstock originating from a renewable source is 5-60 wt%, such as 10 or 50 wt%.

14. The process according to any one of claims 10-13, wherein the one or more impurities is a phosphorous (P)-containing impurity and / or a silicon (Si)-containing impurity; said hydrocarbon feedstock contains 0.5-1000 ppm P and / or 0.5-500 ppm Si.

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