SHELL IMPREGNATED CATALYST AND PROCESS FOR PRODUCING A SHELL IMPREGNATED CATALYST BODY

Abstract

A process for producing a catalyst, comprising the steps of modifying a carrier by a first impregnation with at least one alkaline earth metal in a first metal precursor solution, the first metal precursor being decomposed to form at least one metal oxide or metal hydroxide, thereby obtaining a modified carrier. A second impregnation is carried out by incipient wetness by a second precursor solution comprising at least one metal Me in a second solution. Finally, the second precursor is decomposed, thereby obtaining a catalyst body having an enrichment of the at least one metal Me in the outer shell of the catalyst body, the metal being present in a concentration having either as an egg-shell profile or a hammock profile.

Claims

1. A process for producing a catalyst, said process comprising the steps of: providing a carrier, modifying said carrier by a first impregnation with at least one alkaline earth metal in a first metal precursor solution, decomposing the first metal precursor to form at least one metal oxide or metal hydroxide thereby obtaining a modified carrier, carrying out a second impregnation by incipient wetness by a second precursor solution comprising at least one metal Me in a second solution, and decomposing the second precursor thereby obtaining a catalyst body having an enrichment of the at least one metal Me in the outer shell of the catalyst body, said at least one metal being present in a concentration having either an egg-shell profile and/or a hammock profile.

2. A process according to claim 1, wherein the carrier is alumina spinel and/or calcium aluminate.

3. A process according to claim 1, wherein carrier has a pore volume 200-400 ml/kg, and/or BET surface area 2-50 m.sup.2/g.

4. A process according to claim 1, comprising repeating the second impregnation one or more times.

5. A process according to claim 1, wherein the first precursor solution is a nitrate, carbonate or hydroxide of the alkaline earth metals.

6. A process according to claim 1, wherein the first decomposition is carried out at 350-550 C.

7. A process according to claim 1, wherein the alkaline earth metal is taken from the group of Mg, Ca, Sr and/or Ba.

8. A process according to claim 1, wherein the alkaline earth metal concentration is 0.5-10 wt %, after impregnation.

9. A process according to claim 1, wherein the second solvent is a metal Me precursor in the form of nitrate, acetate, citrate, EDTA and/or EDA.

10. A process according to claim 1, wherein the metal Me is Ni, Ru, Rh, Ir, Pd and/or Pt.

11. A process according to claim 1, wherein the metal Me is Ni, Ru and/or Rh.

12. A process according to claim 1, wherein the impregnated carrier is dried between the second impregnation and the second decomposition.

13. A process according to claim 1, wherein the second decomposition is carried out at 350-600 C.

14. A process for producing a syngas, said process comprising at least one reforming step of contacting a feed stream with a catalyst according to claim 1, and wherein the reforming step comprises steam reforming, primary reforming, secondary reforming auto thermal reforming and/or partial oxidation.

Description

EXAMPLES AND DETAILED DESCRIPTION OF THE INVENTION

[0066] In the below various examples are provided. The examples are to be regarded as exemplary in order to illustrate and elaborate on steps of the method and catalyst body product. The examples are not to be construed as limiting to the invention.

Example I

[0067] Carrier:

[0068] A magnesium alumina spinel carrier containing 92 wt % MgAl.sub.2O.sub.4 and 8 wt % Al.sub.2O.sub.3 with a pore volume of 260 ml/kg, a porosity of 46% and a BET surface area of 20 m2/g.

[0069] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Ca(NO.sub.3).sub.2 solution at room temperature for half an hour to obtain 3 wt % CaO on the carrier. After impregnation the calcium nitrate is decomposed at 550 C.

[0070] Impregnation of the modified carrier with a nickel metal precursor:

[0071] The carrier is impregnated by incipient wetness at room temperature with a nickel nitrate solution containing 7 wt % Ni. After impregnation the nickel nitrate is decomposed at 450 C.

Example II

[0072] Carrier: A carrier as described in example I is used.

[0073] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness at room temperature with a Ca(NO.sub.3).sub.2 solution as described in example I, Carrier.

[0074] Impregnation of the modified carrier with a nickel metal precursor:

[0075] The carrier is impregnated by incipient wetness at room temperature with a 0.6 M (M stands for molar concentration and this abbreviate is used throughout the document) nickel acetate solution. After impregnation the nickel acetate is decomposed at 450 C.

Example III

[0076] Carrier: A carrier as described in example I is used.

[0077] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Ca(NO.sub.3).sub.2 solution as described in example I carrier Impregnation of the modified carrier with a nickel metal precursor:

[0078] The carrier is impregnated by incipient wetness at 80 C. with a nickel citrate solution containing 9 wt % Ni. The solution was prepared by dissolving 7.6 g nickelhydroxycarbonate containing 42% Ni and 11.4 g citric acid in 15 ml water at 80 C. After impregnation the nickel citrate is decomposed at 450 C.

Example IV

[0079] Carrier: A carrier as described in example I is used.

[0080] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution to obtain 3 wt % MgO on the carrier. After impregnation the magnesium nitrate is decomposed at 350 C.

[0081] Impregnation of the modified carrier with a nickel metal precursor:

[0082] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example V

[0083] Carrier: A carrier as described in example I is used.

[0084] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution as described in example IV.

[0085] Impregnation of the modified carrier with a nickel metal precursor:

[0086] The carrier is impregnated by incipient wetness at 40 C. for half an hour with a 1.2 M nickel EDTA solution. The Ni-EDTA solution is prepared by dissolving 11.2 g EDTA in 30 ml concentrated ammonia solution at 40 C. and adding 11.2 g nickel nitrate. After impregnation the nickel EDTA is decomposed at 450 C.

Example VI

[0087] Carrier:

[0088] A calciumaluminate carrier containing 53 wt % CaAl.sub.4O.sub.7, 33 wt % CaAl.sub.12O.sub.19, 13 wt % Al.sub.2O.sub.3 and 1 wt % MgAl.sub.2O.sub.4 with a pore volume of 280 ml/kg, a porosity of 46% and a BET surface area of 2 m.sup.2/g.

[0089] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with an Ca(NO.sub.3).sub.2 solution as described in example I.

[0090] Impregnation of the modified carrier with a nickel metal precursor:

[0091] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example VII

[0092] Carrier: A carrier as described in example I is used.

[0093] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution as described in example IV.

[0094] Impregnation of the modified carrier with a nickel metal precursor:

[0095] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example VIII

[0096] Carrier: A carrier as described in example I is used.

[0097] Impregnation of the carrier with an alkaline earth metal:

[0098] The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution as described in example IV.

[0099] Impregnation of the modified carrier with a nickel metal precursor:

[0100] The carrier is impregnated by incipient wetness at room temperature with a 0.5 M nickel ethylenediamine solution (nickel-EDA). The solution was prepared by dissolving 4.4 g of nickel-nitrate in 30 ml demineralized water and adding 1.8 g of ethylenediamine. After impregnation the nickel EDA is decomposed at 450 C.

Example IX

[0101] Carrier: A carrier as described in example I is used.

[0102] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution as described in example IV.

[0103] Impregnation of the carrier with a Ru metal precursor: The carrier is impregnated by incipient wetness with a solution of rutheniumnitrosylnitrate to obtain 0.5 wt % Ru on the carrier. The impregnation liquor was prepared by diluting with water a commercial available solution containing 8.2% rutheniumnitrosylnitrate. After impregnation the catalyst is dried at 80 C. for one hour.

Example X

[0104] Carrier: A carrier containing magnesium alumina spinel (MgAl.sub.2O.sub.4) and a-alumina with a pore volume of 406 ml/kg, a porosity of 62% and a BET surface area of 4 m.sup.2/g

[0105] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a 3.5 M Mg(NO.sub.3).sub.2 solution. Calcined for two hours at 550 C.

[0106] Impregnation of the carrier with a metal precursor solution:

[0107] Impregnation for 6 minutes by incipient wetness with a solution containing 0.26 M Rh (as Rh(NO.sub.3).sub.3), 0.4 M Al (as Al(NO.sub.3).sub.3) and 2.8 M Mg (as Mg(NO.sub.3).sub.2), where the pH of the solution was adjusted to about 3-3.5 with aqueous ammonia. Final calcination at 750 C. for 2 hours.

Example XI

Comparative Example

[0108] Carrier: A carrier as described in example I is used. Impregnation of the carrier with a nickel metal precursor: The carrier is impregnated by incipient wetness at room temperature with a 0.6 M nickel acetate solution. After impregnation the nickel acetate is decomposed at 450 C. The impregnation and calcination is repeated two times.

Example XII

Comparative Example

[0109] Carrier: A carrier as described in example I is used. Impregnation of the carrier with a nickel metal precursor: The carrier is impregnated with a nickel citrate solution as described in example III. The impregnation and calcination was repeated one time.

Example XIII

Comparative Example

[0110] Carrier: A carrier as described in example I is used. Impregnation of the carrier with a nickel metal precursor: The carrier is impregnated by incipient wetness at 80 C. with a nickel nitrate solution containing 9 wt % Ni. After impregnation the nickel nitrate is decomposed at 450 C. The impregnation and calcination was repeated one time more.

Example XIV

[0111] Carrier: A carrier as described in example VI is used.

[0112] Impregnation of the carrier with a nickel metal precursor: The carrier is impregnated with a nickel citrate solution according to the procedure described in example XIII.

Example XV

[0113] Carrier: A carrier as described in example I is used.

[0114] Impregnation of the carrier with a Ru metal precursor: The carrier is impregnated according to the procedure given in example IX.

Example XVI

[0115] Carrier: A carrier as described in example I is used.

[0116] Impregnation of the carrier with an alkaline earth metal: The carrier from example I is impregnated by incipient wetness with a Ca(NO.sub.3).sub.2 solution at room temperature for half an hour to obtain 1.5 wt % CaO on the carrier. After impregnation the calcium nitrate is decomposed at 550 C.

[0117] Impregnation of the modified carrier with a nickel metal precursor:

[0118] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example XVII

[0119] Carrier: A carrier as described in example I is used.

[0120] Impregnation of the carrier with an alkaline earth metal: The carrier from example I is impregnated by incipient wetness with a Ca(NO.sub.3).sub.2 solution at room temperature for half an hour to obtain 5.0 wt % CaO on the carrier. After impregnation the calcium nitrate is decomposed at 550 C.

[0121] Impregnation of the modified carrier with a nickel metal precursor:

[0122] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example XVIII

[0123] Carrier: A carrier as described in example I is used.

[0124] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution to obtain 1.5 wt % MgO on the carrier. After impregnation the magnesium nitrate is decomposed at 350 C.

[0125] Impregnation of the modified carrier with a nickel metal precursor:

[0126] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

Example XIX

[0127] Carrier: A carrier as described in example I is used.

[0128] Impregnation of the carrier with an alkaline earth metal: The carrier is impregnated by incipient wetness with a Mg(NO.sub.3).sub.2 solution to obtain 4.5 wt % MgO on the carrier. After impregnation the magnesium nitrate is decomposed at 350 C.

[0129] Impregnation of the modified carrier with a nickel metal precursor:

[0130] The carrier is impregnated by incipient wetness with a nickel citrate solution as described in example III. After impregnation the nickel citrate is decomposed at 450 C.

[0131] The metal-profile of the catalyst tablets has been examined by the applicant by scanning electron microscopy analysis (SEM) using standardless Energy Dispersive X-ray spectroscopy (EDS)-analysis for chemical analysis. Prior to analysis the catalysts were reduced in hydrogen and pasivated in clean air (O.sub.2/N.sub.2 mix with low O.sub.2 content) at room temperature. Ni, Rh based catalysts were reduced at 525 C. and Ru-based catalysts at 350 C. The samples were cleaved into half tablet, which were embedded in epoxy and polished to obtain a flat surface. The embedded samples were re-embedded; ground and polished (with water present). To prevent charging during the SEM analysis, the samples were coated with carbon. The obtained profiles are displayed in FIGS. 1-4. The profile type and shell thickness are summarized in Table 1 and 2. The shell thickness is calculated as the distance from the outer surface of the catalyst body to the position where the metal concentration is 150% of the average metal concentration, as calculated as the average concentration from 800 m and to the centre of the catalyst body.

[0132] The metal concentration in the shell is calculated as the average of the measured metal concentrations in the shell.

[0133] The maximum metal concentration in the shell is the highest metal concentration measured in the shell, which is typically very close to the outer surface.

[0134] Hammockshell in table 1 means that there is a shell formation but the metal concentration does not decrease to zero or substantially zero (or below the minimum measurement threshold 0.5 wt %) in the centre.

[0135] For the Ru-containing samples wavelength dispersive X-ray spectroscopy (WDS) was used to determine the Ru concentration profiles. With this method Ru standards are used to enable an accurate determination of the Ru concentration which is lower. Hence, WDS has a lower detection limit than EDS.

TABLE-US-00001 TABLE 1 Metal profile type and concentration of metal in the catalyst body Metal Maximum metal Profile Concentration concentration type/thickness in shell in shell Example Carrier Precursor m wt % wt % I MgAl.sub.2O.sub.4/CaO Ni-nitrate shell - 742 4 5 II MgAl.sub.2O.sub.4/CaO Ni-acetate shell - 176 1 1.5 III MgAl.sub.2O.sub.4/CaO Ni-citrate shell - 155 4 7 IV MgAl.sub.2O.sub.4/MgO Ni-citrate shell - 46 7 8 V MgAl.sub.2O.sub.4/MgO Ni-EDTA Hammock 3 4 Shell-376 VI CaAluminate/ Ni-citrate shell - 447 4 6 CaO VII CaAluminate/ Ni-citrate hammock 8 11 MgO shell-103 VIII MgAl.sub.2O.sub.4/MgO Ni-EDA hammock 2 2.2 shell - 90 IX MgAl.sub.2O.sub.4/MgO Ru(NO)(NO.sub.3).sub.3 shell-90 2 2.6 X MgAl.sub.2O.sub.4/MgO Rh-nitrate shell-200 2 3.9

TABLE-US-00002 TABLE 2 Comparative example: Metal profile type and concentration of metal in the catalyst body Metal Exam- Profile Concentration ple Carrier Precursor type/thickness wt % XI MgAl.sub.2O.sub.4 Ni-acetate homogeneous 3 XII MgAl.sub.2O.sub.4 Ni-citrate homogeneous 4-11 XIII MgAl.sub.2O.sub.4 Ni-nitrate Homogeneous 8 XIV CaAluminate Ni-citrate Homogeneous 12 XV MgAl.sub.2O.sub.4 Ru(NO)(NO.sub.3).sub.3 homogeneous 1

BRIEF DESCRIPTION OF THE DRAWINGS

[0136] FIG. 1. Nickel concentration profiles measured by EDS analysis along the cross-section of the catalyst body for examples I-VIII. The line scans were measured from the outer surface of the catalyst body and inwards. There is an uncertainty of +/30 m on the measured position. 1000 m has been used as the center for these plots and related table values.

[0137] FIG. 2. Nickel concentration profiles measured by EDS analysis along the cross-section of the catalyst body for examples XI-XIV. The line scans were measured from the outer surface of the catalyst body and inwards. There is an uncertainty of +/100 m on the measured position.

[0138] FIG. 3. Ruthenium concentration profiles measured by wavelength dispersive X-ray spectroscopy (WDS) analysis along the cross-section of the catalyst body for examples IX and XV. The line scans were measured from the outer surface of the catalyst body inwards.

[0139] FIG. 4. Rhodium concentration profiles measured by EDS analysis along the cross-section of the catalyst body for example X. The line scans were measured from the outer surface of the catalyst body and inwards.

[0140] FIG. 5. Nickel concentration profiles measured by EDS analysis along the cross-section of the catalyst body for examples I-XVI-XVII. The line scans were measured from the outer surface of the catalyst body inwards. 1.5 wt % CaO results in an increased Ni concentration in the shell region and a clear and sharp shell formation at both 3 and 5 wt % CaO. It appears that 5 wt % results in a slightly sharper shell than 3 wt %.

[0141] FIG. 6. Nickel concentration profiles measured by EDS analysis along the cross-section of the catalyst body for examples IV-XVIII-XIX. The line scans were measured from the outer surface of the catalyst body inwards.

[0142] 1.5 wt % MgO results in a clear shell region and a clear and sharp shell formation is also registered at both 3 and 4.5 wt % MgO. It appears that 3 wt % results in a slightly sharper shell than 5 wt %.

[0143] FIG. 7. Optical images of 4 mm impregnated cylinders cut in the middle through the cross-section. The images reveal the areas containing nickel (grey or black) and the areas not containing nickel (white). For these examples, the same spinel and Ca-aluminate carriers were used as starting point as described in examples I and VI but shaped (pressed) into 4 mm cylinders. The cylinders where first pre-modified with different amounts of either CaO or MgO, as described in examples I and IV, and subsequently impregnated with either Ni nitrate, Ni acetate or Ni citrate solutions, as described in examples I, II and III. The details on the carrier, wt % of the pre-modifier and the nickel precursor used are described in the following: [0144] (A) Magnesium alumina spinel carrier without pre-modifier impregnated with Ni nitrate sol. [0145] (B) Calcium aluminate carrier without pre-modifier impregnated with Ni nitrate sol. [0146] (C) Magnesium alumina spinel carrier pre-modified with 4.5 wt % MgO and impregnated with Ni nitrate sol. [0147] (D) Calcium aluminate carrier pre-modified with 4.5 wt % MgO and impregnated with Ni nitrate sol. [0148] (E) Calcium aluminate carrier pre-modified with 1.5 wt % MgO and impregnated with Ni acetate sol. [0149] (F) Magnesium alumina spinel carrier pre-modified with 3.0 wt % CaO and impregnated with Ni citrate sol. [0150] (G) Magnesium alumina spinel carrier pre-modified with 4.5 wt % MgO and impregnated with Ni citrate sol. [0151] (H) Magnesium alumina spinel carrier pre-modified with 4.5 wt % MgO and impregnated with Ni acetate sol. [0152] (I) Magnesium alumina spinel carrier pre-modified with 5.0 wt % CaO and impregnated with Ni acetate sol. [0153] (J) Calcium aluminate carrier pre-modified with 4.5 wt % MgO and impregnated with Ni acetate sol.