POROUS MATERIAL FOR REMOVING IMPURITIES IN FEEDSTOCKS

Abstract

A porous material including alumina, the alumina including alpha-alumina, the porous material including one or more metals selected from Co, Mo, Ni, W and combinations thereof, and the porous material having a BET-surface area of 1-110 m2/g, a total pore volume of 0.50-0.80 ml/g, as measured by mercury intrusion porosimetry, and a pore size distribution (PSD) with at least 30 vol% of the total pore volume being in pores with a radius ≥ 400 Å, suitably pores with a radius ≥ 500 Å, A process for removing impurities such as phosphorous (P) from a feedstock by contacting the feedstock with a guard bed including the above porous material. A guard bed for a hydrotreatment system including the porous material, a hydrotreatment system including a guard bed which includes the porous material and a downstream hydrotreatment section including at least one hydrotreatment catalyst.

Claims

1. A porous material comprising alumina, said alumina comprising alpha-alumina, said porous material comprising one or more metals selected from Co, Mo, Ni, W, and combinations thereof, said porous material having a BET-surface area of 1-110 m.sup.2/g, wherein the porous material has a total pore volume of 0.50-0.80 ml/g, as measured by mercury intrusion porosimetry, and the porous material has a pore size distribution (PSD) with at least 30 vol% of the total pore volume, being in pores with a radius ≥ 400 Å.

2. The porous material according to claim 1, with up to 60 vol% of the total pore volume being in pores with a radius below 400 Å.

3. The porous material according to claim 1, wherein the content of alpha-alumina is 50-100 wt%.

4. The porous material according to claim 1, the alumina further comprising theta-alumina.

5. The porous material according to claim 1, wherein the content of the one or more metals is 0.25-20 wt%.

6. The porous material according to claim 1, further comprising a compound selected from Al-borates, calcium aluminates, silicon aluminates, and combinations thereof.

7. The porous material according to claim 1, wherein the one or more metals comprise Mo and its content is 0.5-15 wt%.

8. The porous material according to claim 7, further comprising 0.1-5 wt% of at least one of Ni, Co, and W.

9. The porous material according to claim 7, further comprising 0.05-0.5 wt% of Ni.

10. The porous material according to claim 1, wherein the BET-surface area is 1-70 m.sup.2/g.

11. The porous material according to claim 1, wherein the porous material is an extruded or tabletized pellet having a shape selected from trilobal, tetralobal, pentalobal, cylindrical, spherical, hollow and combinations thereof.

12. A process for removing one or more impurities from a feedstock, said process comprising the step of contacting said feedstock with a guard bed comprising a porous material according to claim 1, thereby providing a purified feedstock.

13. The process of claim 12, 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.

14. The process according to claim 1, which process is carried out at a temperature of 100-400° C.

15. The process according to claim 1, wherein the feedstock is: i) a renewable source obtained from a raw material of renewable origin; or ii) a feedstock originating from a fossil fuel; or iii) a feedstock originating from combining a renewable source according to i) and a feedstock originating from a fossil fuel according to ii).

16. The process according to claim 15, wherein the portion of the feedstock originating from a renewable source is 5-60 wt%.

17. The process according to claim 13, wherein the one or more impurities is a phosphorous (P)-containing impurity and said feedstock contains 0.5-1000 ppm P.

18. The process according to claim 12, wherein the purified feedstock is subsequently processed in a hydrotreatment stage in the presence of a hydrotreatment catalyst.

19. A guard bed for a hydrotreatment system, said guard bed comprising a porous material according to claim 1.

20. A hydrotreatment system for hydrotreating a feedstock, said hydrotreatment system comprising: a guard bed comprising a porous material according to claim 1; and a hydrotreatment section comprising at least one hydrotreatment catalyst, arranged downstream of said guard bed.

21. A method of using a porous material according to claim 1 as a phosphorus guard in a hydrotreatment process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] FIG. 1 shows the pore size distribution (PSD) by mercury intrusion porosimetry of porous materials according to the invention.

[0077] FIG. 2 shows the pore volume distribution and total pore volume by mercury intrusion porosimetry of porous materials according to the invention.

[0078] FIG. 3 shows in the X-axis the vol.% of pores having radius greater than 400 Å.

[0079] FIG. 4 shows SEM (scanning electron microscope) pictures of P-capture in samples according to the prior art (low penetration of P) and according to the invention (deep penetration of P).

DETAILED DESCRIPTION

Examples

[0080] A porous material according to the invention is packed together with a reference porous material, i.e. a conventional and commercially available refinery catalyst having a predominantly gamma-alumina carrier impregnated with 3 wt% Mo, in separate compartments, and for a period of time, normally 8-12 months, brought into contact with a mixture of 50% renewable feed and 50% fossil feed, and with a 100% renewable feed, under hydrotreatment conditions. Prior to testing, the samples are analyzed by XRD for determination of e.g. alumina phases. At the end of the testing, the samples are rinsed by extraction with xylene, dried in vacuum and analysed for metals/P capture (XRF, X-ray fluorescence analysis according to EN ISO 12677:2011), SEM, Carbon and Sulphur (C+S; LECO analysis, ASTM E1915-13) and BET-surface area (ASTM D4567-19).

[0081] For determination of alumina phases, XRD is used. Accordingly, powder X-ray diffraction patterns were collected on an XPertPro instrument configured in Bragg-Brentano mode using CuKalpha radiation. Rietveld analysis using the TOPAS software was used to quantify the phase composition.

[0082] For determination of total pore volume and pore size distribution, mercury intrusion porosimetry is conducted according to ASTM D4284.

[0083] The porous materials were prepared by calcination at high temperatures of 1100-1200° C. in air for 2-3 hours and without addition of additives of alumina materials used as catalyst carriers and comprising 50 wt% or more gamma-alumina.

[0084] FIG. 1 shows the PSD of four samples used in the testing. Note that the X-axis is logarithmic. Sample 1 is the reference according to the prior art, i.e. the above mentioned conventional and commercially available refinery catalyst having a predominantly gamma-alumina carrier. Samples 2-4 are porous materials according to the invention. It is observed that for the samples according to the invention, a significant portion of the pores have a pore radius 400 Å and above, or 500 Å and above. The formation of these big pores which serve for the P-capture is attributed to the formation of alpha-alumina and optionally also theta-alumina.

[0085] The smaller pores below 400 Å or below 500 Å may be advantageous to promote some hydrotreating capability to the porous materials. Hence, samples 3-4 in particular provide small pores to accommodate a little amount of the metal, for instance about 1 wt% Mo.

[0086] The balance of finding a porous material which has a high capacity for impurity capture, in particular P-capture, while at the same time being able to accommodate metals for hydrotreating, yet without promoting coking, is very delicate. Big pores as such do not guarantee a better guard. For instance, the peaks in the pore region in FIG. 1 above 2500 Å up to about 5000 Å do not necessarily make the corresponding porous materials (samples 2 to 4) a better guard material than a similar porous material, i.e. one having at least 30 vol% of the total pore volume in pores with a radius equal to or above 400 Å or radius equal to or above 500 Å, yet not showing a peak in this pore region 2500-5000 Å, or with no pores in this region (2500-5000 Å). At the same time, simply having a porous material with a significant amount of micropores or pores below about 80 Å or below 40 Å, as is normally wanted to provide high surface area for the deposition of metals and thereby catalytic hydrotreating activity, impairs the capacity of the porous material as a P-guard by micropores blocking the access to bigger pores.

[0087] FIG. 2 and FIG. 3 show the total pore volume (PV) and corresponding distribution of pores. Porous materials corresponding to samples 2 to 4 according to the invention show total pore volumes in the range 0.50-0.80 ml/g, more specifically about 0.60 ml/g, with at least 30% of the total pore volume in pores with radius above 400 Å. For instance, sample 2 being about 90 wt% alpha-alumina and about 10 wt% theta-alumina, shows 99% of the total pore volume in pores above 400 Å, while the reference sample 1 shows only about 20% of the total pore volume in pores above 400 Å.

[0088] Table 1 shows the content of the alumina phases in the samples, as measured by XRD. No additive was used in the preparation as stabilizing agent and thus no Al-borate, calcium aluminate or silicon-aluminate crystalline phases are detected.

TABLE-US-00001 Sample Alpha-alumina (wt %) Theta-alumina (wt %) Gamma-alumina (wt %) BET-surface area (m.sup.2/g) 1 - ref. 0 0 >95 150-200 2 98 2 0 9-10 3 68 32 0 40-45 4 48 52 0 50-55

[0089] Table 2 below shows the results of impurities-capture, in particular P and Fe, as well as coking (C wt%) with the porous materials from 50% renewables and 100% renewables in the feedstock.

[0090] The samples running with 50% renewables show up to 600% higher P-capture than the reference (sample 1). The samples running with 100% renewables show up to 51% more P-capture. It is also shown that if a small amount of Mo is present in the fresh porous material, for instance about 1 wt% Mo, coking decreases significantly (see underlined values) compared to the corresponding samples without metal (3′, 4′). Surprisingly, despite the low surface area of the samples of the invention, the addition of e.g. 0.9 and 0.7 wt% Mo resulted in a significantly lower coke formation.

[0091] FIG. 4 shows SEM pictures of the penetration of P into the porous material having a tetralobal shape as P-maps (brighter means more P), with reference sample 1 (top) and sample 2 (bottom). For the reference sample it is observed that P is only present on the surface of the material, whereas in sample 2 a high level of P penetration takes place.

TABLE-US-00002 Fresh porous material After use Sample Renewables wt.% in feedstock Mo in fresh porous material (wt%) C (wt.%) P-capture (kg/m.sup.3) Relative P-capture Fe-capture (kg/m.sup.3) 1 - ref. 50 2.90 5.87 14.0 1 4.7 3 50 0.70 1.27 78.5 5.6 8.6 3′ 50 - 5.04 77.7 5.6 9.0 1- ref. 100 2.90 3.05 43.3 1 5.5 4 100 0.92 3.91 65.5 1.5 5.2 4′ 100 - 17.10 55.1 1.3 5.3

[0092] Further experiments were conducted with another 100 wt% renewable feedstock, and with the content of the alumina phases in fresh porous materials (samples 5, 6, 7; see below Table 3), as measured by XRD, being about 70 wt% alpha-alumina and 30 wt% theta alumina, and surface area in the range 25-40 m.sup.2/g. Sample 1′-ref. is a new reference tested together with samples 5-7. Sample 1′-ref. has 100 wt% gamma alumina, a surface area of about 150 m.sup.2/g and contains slightly more molybdenum (about 3.1 wt%) than sample 1-ref. Again, no additive was used in the preparation as stabilizing agent and thus no Al-borate, calcium aluminate or silicon-aluminate crystalline phases are detected. Sample 5 is free of molybdenum and nickel. Sample 6 contains about 1 wt% of molybdenum. Sample 7 contains about 1.2 wt% molybdenum and additionally about 0.1 wt% nickel, more specifically 0.14 wt% Ni. All fresh porous materials (samples 1-7) are free of Co and/or W. The results for samples are shown in Table 3.

[0093] Significant P-capture is again achieved. Despite the low surface area of the samples of the invention, the addition of about 1 wt% Mo resulted in a significantly lower coke formation. By further addition of a small amount of nickel, about 0.1 wt%, coke formation is further reduced without significantly impairing P-capture.

[0094] The use of molybdenum optionally together with nickel is particularly more advantageous when operating with 100% renewable feedstock, as the P-capture significantly increases with respect to the samples not using molybdenum.

TABLE-US-00003 Fresh porous material After use Sample Renewables wt.% in feedstock Mo in fresh porous material (wt%) C (wt.%) P-capture (kg/m.sup.3) Relative P-capture Fe-capture (kg/m.sup.3) 1′ - ref. 100 3.06 5.46 7.4 1 0.3 5 100 - 7.84 10.7 1.4 0 6 100 1.05 3.14 34.9 4.7 0.4 7* 100 1.21 2.70 34.4 4.7 0.5 *Sample 7 is a NiMo porous material containing 0.14 wt% nickel