WO2019055222A1

WO2019055222A1 - Method for manufacturing higher performance catalysts, catalysts et method of hydrogenation of aromatic hydrocarbons

Info

Publication number: WO2019055222A1
Application number: PCT/US2018/048689
Authority: WO
Inventors: Wenyih Frank Lai; Paul Podsiadlo; Nicholas S. ROLLMAN; Matthew S. IDE
Original assignee: Exxonmobil Research And Engineering Company
Priority date: 2017-09-15
Filing date: 2018-08-30
Publication date: 2019-03-21

Abstract

A method for preparing an extruded catalyst material is disclosed. The method includes steps of mixing a binder, a mesoporous silica/alumina material, water and one or more Pt or Pd precursors to form an extrudable paste, extruding the paste to form a green catalyst extrudate and calcining the extrudate to form a calcined extrudate catalyst material. Catalysts made by such a method and methods for using them, for example for hydrotreatment, are also disclosed.

Description

METHOD FOR MANUFACTURING HIGHER PERFORMANCE CATALYSTS, CATALYSTS ET METHOD OF HYDROGENATION OF AROMATIC HYDROCARBONS

FIELD

[0001] The present application relates to methods for preparing metal-containing catalysts, to the catalysts so prepared and to methods for using the catalysts.

BACKGROUND

[0002] Many commercial catalysts contain large pore volume and large surface area active materials or supports (e.g. mesoporous silica or zeolite catalysts). For some catalyst applications, these materials may require inclusion of catalytically active metals. This is often done after the base support has been prepared, e.g. after extrusion, by a process termed "impregnation". The typical impregnation process calls for preparing a solution of precursors of the metals, spraying the solution onto a support, drying the support to remove water, and calcining the dried support to decompose metals salts and form active metals centers. These impregnation process steps add cost and processing time to catalyst manufacturing schemes.

[0003] Furthermore, large pore volume catalysts may require extra precautions and optimization of the drying process, in order to carefully remove the water absorbed during the spray impregnation. The impregnation typically calls for spraying a water solution up to the extrudate saturation level in order to ensure uniform distribution of the metals throughout the extrudate, which for highly porous supports, can result in large water uptake. In order to prevent metals maldistribution, the drying process has to be optimized in terms of drying rates. Inaccurate calculation of impregnation solution volumes or non-optimum drying rates can lead to maldistribution of the active metals and underperformance of the finished catalyst.

[0004] Separately, shape-forming of large-pore-volume active materials, can provide geometries with reduced specific surface areas (surface-to-volume ratios) in order to impart sufficient mechanical properties. These shapes may include: cylinders, squares, hexagons, or triangles. Typically, increasing porosity reduces crush strength of the finished catalyst materials, while high crush strength is important for maintaining good integrity of the catalyst bed in a fixed bed reactor. While good for mechanical properties, in some applications, some catalyst shapes may also cause undesirable increases in pressure drops in the reactors due to high fill factors of the solid.

SUMMARY

[0005] A method for making a catalyst material incorporating one or more noble metals, such as platinum (Pt) or palladium (Pd) is disclosed. Accordingly, there is provided a method for producing a catalyst material that includes mixing a binder, a mesoporous silica/alumina material, for example MCM-41, water and one or more Pt or Pd precursors to form an extrudable paste, extruding the paste to form a green catalyst extrudate, and calcining the extrudate to form a calcined extrudate catalyst material. The green catalyst extrudate can optionally be dried to remove water prior to the calcining step.

[0006] In the disclosed method, at least one Pt precursor can be a solution of platinum chloride or platinum tetraamine nitrate. Additionally or alternatively at least one Pd precursor can be palladium chloride or palladium tetraamine nitrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A is a photograph of a batch of calcined catalyst extrudate prepared by the noble metal solution impregnation method in Example 1. Figure IB shows the profile of Pt distribution observed by EMPA across the cross section of 5 different samples of the calcined catalyst prepared by the noble metal solution impregnation method in Example 1. Figure 1C shows the profile of Pd distribution observed by EMPA across the cross section of 5 different samples of the calcined catalyst prepared by the noble metal solution impregnation method in Example 1.

[0008] Figure 2A is a photograph of a batch of calcined catalyst extrudate prepared by the noble metal "muller addition" method in Example 2. Figure 2B shows the profile of Pt distribution and Figure 2C shows the profile of Pd distribution observed by EMPA across the cross section of 5 different samples of the calcined catalyst prepared by the noble metal "muller addition" method in Example 2. Figure 2D shows the cross section of a piece of the calcined catalyst extrudate of Example 2 and the line of EMPA scanning.

[0009] Figure 3A is a photograph of a batch of calcined catalyst extrudate prepared by the noble metal "muller addition" method in Example 3. Figure 3B shows the profile of Pt distribution and Figure 3C shows the profile of Pd distribution observed by EMPA across the cross section of 5 different samples of the calcined catalyst prepared by the noble metal "muller addition" method in Example 3. Figure 3D shows the cross section of a piece of the calcined catalyst extrudate of Example 3 and the line of EMPA scanning.

[0010] Figure 4A is a photograph of a batch of calcined catalyst extrudate prepared by the noble metal "muller addition" method in Example 4. Figure 4B shows the profile of Pt distribution and Figure 4C shows the profile of Pd distribution observed by EMPA across the cross section of 5 different samples of the calcined catalyst prepared by the noble metal "muller addition" method in Example 4. Figure 4D shows the cross section of a piece of the calcined catalyst extrudate of Example 4 and the line of EMPA scanning.

[0011] Figures 5A and 5B show photographs of green and calcined extrudates prepared in Examples 5A and 5B, respectively. [0012] Figure 6A and Figure 6B are photographs of calcined extrudates prepared in Examples 6A and 6B, respectively.

[0013] Figure 7 is a graph comparing the aromatics saturation activity with temperature of the catalyst of Example 6A with that of the catalyst of the reference Example 1.

[0014] Figure 8A and Figure 8B are examples of an expanded trilobe cross-section and of an expanded quadralobe cross-section, respectively.

[0015] Figure 9 illustrates a radius drawn through a cross-section of a catalyst extrudate and indicates a segment of the radius within a certain distance of the surface ("S") and a segment of the radius spanning the center of the cross-section ("C").

DETAILED DESCRIPTION

[0016] A method for preparing high-surface area extruded catalysts that exhibit one or more of improved metals distribution, enhanced specific surface area, and improved mechanical strength is provided. The disclosed method also may allow for lower catalyst manufacturing cost.

[0017] In the disclosed method, precursors of precious metals precursors are mixed together with a (meso) porous material, binder, and water, prior to extrusion ("muller addition"). This procedure eliminates additional steps associated with post-extrusion metals impregnation which reduces manufacturing time and saves the processing costs associated with the impregnation steps.

[0018] The disclosed process can substantially increase single pellet cross-sectional metals distribution and can additionally or alternatively substantially reduce pellet-to-pellet metals loading variation, compared to traditional spray impregnation. This dimension of improvement can in some instances provide another cost-saving by allowing reduction of the overall metals content of the catalyst material but with substantially the same overall catalyst performance. In catalysts where metals are distributed non-uniformly, the catalytic metals are often underutilized.

[0019] To enhance the specific surface area of the extruded catalyst, a so-called "expanded trilobe" or "expanded quadralobe" design of the pellet cross section can be applied to extrusion of the metals/porous material/binder/water paste. (E.g. as described in the application bearing Attorney Docket No. 2017EM290, filed September 15, 2017, hereby incorporated in its entirety by reference.) Generally, an expanded trilobe or expanded quadralobe pellet has a cross-section comprising a central triangular or rectangular portion having a part-circular lobe at each vertex, wherein the center of the part circle of each lobe and diameter of each lobe are such that adjacent lobes do not intersect, (e.g. as in Figures 8A and 8B.) Expanded trilobe cross sections can show >50% increased specific surface area when compared to cylindrical cross sections. [0020] Accordingly, disclosed herein is a method for producing a catalyst material comprising mixing a binder, a mesoporous silica/alumina material, water and one or more Pt or Pd precursors to form an extrudable paste; extruding the paste to form a green catalyst extrudate; and calcining the extrudate to form a calcined extrudate catalyst material. The green catalyst extrudate can be dried to remove water before calcining the extrudate.

[0021] The mesoporous silica/alumina material typically has a Si/Ah ratio of about 50: 1, but the ratio can vary, for example being, 10: 1 or 20: 1 or 25: 1 or 30: 1 or 35: 1 or 40: 1 or 45 : 1 or 60: 1 or 80: 1 or 100: 1 or >100: l .

[0022] In any implementation of the disclosed method, the mesoporous silica material can be MCM-41. The pore size of the mesoporous material can range from 1-20 nm, or from 1 -10 nm, from 1.5 to 8.0 nm, or from 2-10 nm. In instances where the mesoporous material is MCM-41 , the pore size can be from 1.5 to 8.0 nm, and may be from 2 to 6.5 nm.

[0023] In any implementation of the disclosed method, at least one Pt precursor solution can a solution of platinum chloride or platinum tetraamine nitrate. Additionally or alternatively, at least one Pd precursor can be palladium chloride or palladium tetraamine nitrate.

[0024] In any implementation of the disclosed method, the calcining can be performed under an oxidative atmosphere at a temperature of 400-600 °C. The oxidative atmosphere can be air or air mixed with an inert gas such as nitrogen or argon. The calcining temperature can be 450-600 °C, or 450-550 °C or 450-500 °C.

[0025] In any implementation of the disclosed method, the binder can be an alumina binder, a silica binder, a titania binder, a ceria binder, or a zirconia binder, or a mixture of any two or more of them. In some instances, the binder can be an alumina binder having a pseudoboehmite microstructure.

[0026] Also disclosed is a catalyst, which can be prepared as described above, in which the calcined extrudate catalyst material contains of 0.01 - 10 wt% Pt and 0.01- 10 wt% Pd in any ratio of the amount of Pt to the amount of Pd. In some instances of the disclosed catalysts, the calcined extrudate catalyst material can contain 1 -0.3 wt% Pt and 0.2-1.0 wt% Pd and a percentage of Pt less than the percentage of Pd. In some instances, the weight ratio of the amount of Pt to the amount of Pd can be about 1 :3.

[0027] An advantage of the disclosed method can be that the catalyst produced exhibits a low variation in the amount of metal across the cross-section of a catalyst pellet. So, in some catalysts disclosed, the amount of platinum can vary in the range from 0.02 to 0.15 wt% along a line of the cross-section of the calcined extrudate catalyst material. Additionally or alternatively, the amount of palladium can vary from 0.05 to 0.2 wt% along a line of the cross-section of the calcined extrudate catalyst material. In some instances of catalysts as disclosed herein, the amount of platinum can vary in the range from 0.05 to 0.2 wt% along a line of the cross-section of the calcined extrudate catalyst material. Additionally or alternatively, the amount of palladium can vary from 0.15 to 0.4 wt% along a line of the cross-section of the calcined extrudate catalyst material.

[0028] Another way to visualize the difference in the variation of metals distribution across the cross-section of catalyst extrudates is in respect of the difference in concentration of the metals near the surface of the extrudate compared to their concentration near the center of the extrudate. The "impregnation" method utilizing solution spraying of calcined catalyst material usually results in an "eggshell" distribution of the metals, such that the concentration of metals within a specified depth, e.g. 50 microns or 100 microns or 200 microns, from the surface is much higher, as much as 50%, or 2x, 3x, 5x, l Ox, or more, greater than their concentration near the center of the catalyst extrudate.

[0029] Accordingly, the presently disclosed catalyst can be one in which the average amount of platinum varies across the cross-section of an extrudate by 30% or less, or by 25% or less or by 15% or less, between a 100 micron segment radial from the surface of the extrudate and a 100 micron segment of that radius spanning the center of the cross section of the extrudate and the average amount of palladium varies by 30% or less, or by 25% or less, or by 15% or less, between a 100 micron segment radial from the surface of the extrudate and a 100 micron segment of that radius spanning the center of the cross section of the extrudate. (See, e.g. Figure 9.)

[0030] Another advantage of the disclosed catalysts can be that they exhibit a low variation in the total amount of metal loaded among catalyst pellets in a batch of catalyst material.

Accordingly, the disclosed catalysts can exhibit pellet-to-pellet variation in the amount of loaded metal such that the average amount of platinum and/or the average amount of palladium varies by 25% or less, or by 20% or less, or by 15% or less, among different pellets of a population of catalyst pellets.

[0031] Also disclosed are methods for hydrotreating hydrocarbon feeds using the catalysts disclosed herein. Processes such as de-waxing, hydrodeamination and hydrodesulfurization can be performed using catalysts according to the present disclosure by contacting the catalyst with a hydrocarbon feed to be treated with the appropriate catalyst and under conditions sufficient for the desired reactions to occur. (Such conditions are considered known in the art.) Accordingly, another aspect of the disclosure lies in a method of, for example, hydrogenation of aromatic hydrocarbons comprising contacting said aromatic hydrocarbons with any of the catalyst embodiments of the disclosure under conditions effective for at least partially saturating aromatic rings of the aromatic hydrocarbons. (Such conditions are considered well-known in the art.)

[0032] In the Examples below, the disclosed method is applied to preparing noble metal- containing aromatics saturation catalysts incorporating high-surface area/high pore volume MCM-41. The resulting example catalysts showed exceptionally uniform metals distribution and good side crush strength. The enhanced specific surface area provided by the expanded trilobes cross section of some examples may also provide advantages for diffusion limited systems as well as decreasing reactor pressure drops.

[0033] In the Examples below, several formulations of 65/35 (MCM-41/Versal™-300 binder) extrudate with Pt loading of 0.1 to 0.6 wt% and Pd loading of 0.3 to 0.9 wt% are prepared using cylinder and expanded trilobes extrusion dies. These examples are merely illustrative of the present invention and are not to be construed as limiting the scope of the claims below.

Example 1 (Reference) - (0.3/0.9 Pt/Pd coating) Catalyst by solution impregnation

[0034] 65 parts (basis: calcined 538°C) of calcined MCM-41 crystals (with Si: Ah ~ 50: 1) were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" diameter cylindrical catalyst pellets. The green extrudates with crush strength of - 54 lbs/in were then dried in an oven at 121°C overnight. The dried extrudate was calcined in air at 538°C to decompose and remove residual carbon in the extrudate. The calcined extrudate with total surface area of - 646 m²/g was then coated with 0.3/0.9 wt% of Pt/Pd metals. The impregnated catalyst was calcined at about 580°F or lower to convert to the final finished catalyst. A photograph of the finished catalyst is shown in Figure 1 A. Uniformity of metal dispersion in the resultant catalyst was studied by Electron Microprobe Analysis (EMPA). The Pt and Pd profiles across several extrudate pellets are shown in Figures IB and 1C. The EMPA profiles show poor metal dispersion along a line of the cross section and poor consistency of metal incorporation among catalyst pellets, consistent with the variation in the color saturation among the catalyst pellets shown in Figure 1 A.

Example 2 - (0.1/0.3 Pt/Pd) Catalyst by muller addition and Expanded Trilobe insert

[0035] 65 parts (basis: calcined 538°C) of calcined MCM-41 crystals (with SiAh - 50/1) were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) and Pt/Pd precursor solutions in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" diameter expanded trilobe catalyst pellets. The green extrudates were then dried in an oven at 121°C overnight. The dried extrudate was calcined in air at 500°C to decompose and remove residual carbon in the extrudate. The calcined extrudate comprised 0.1/0.36 wt% of Pt/Pd metals loading and exhibited a surface area of 796 m²/g after calcination. A photograph of the finished catalyst is shown in Figure 2A. Crush strength of green extrudates was 89 lbs/in. Uniformity of metal dispersion in extrudate pieces was studied by Electron Microprobe Analysis (EMPA). The Pt and Pd profiles of several extrudate pellets are shown in Figures 2B and 2C and demonstrate improved uniformity of metal dispersion along a line of the pellet cross section as compared with the pellets of Example 1. In addition, the consistency of metal content observed between different catalyst pellets is consistent with the uniformity of the coloring, particularly of the color saturation, among the catalyst pellets shown in Figure 2A.

Example 3 - (0.1/0.3 Pt/Pd) Catalyst by muller addition and Cylinder insert

[0036] 65 parts (basis: calcined 538°C) of once-calcined MCM-41 crystals (with SiAh ~ 50/1) were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) and Pt/Pd precursor solutions in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" diameter cylinder of catalyst. The green extrudates were then dried in an oven at 121°C overnight. The dried extrudate was calcined in air at 500°C to decompose and remove residual carbon in the extrudate. The calcined extrudate comprised 0.1/0.34 wt% of Pt/Pd metals loading and exhibited a surface area of 808 m²/g after calcination. A photograph of the finished catalyst is shown in Figure 3A. Crush strength of green extrudates was 84 lbs/in. Uniformity of metal dispersion in extrudate pieces was studied by Electron Microprobe Analysis (EMPA). The Pt and Pd profiles of several extrudate pellets are shown in Figures 3B and 3C. Uniform metal dispersion along a line of the cross section of a number of catalyst pellets was shown by EMPA and the consistency of metal content observed between different catalyst pellets is consistent with the uniformity of the coloring, particularly of the color saturation, among pieces of the catalyst shown in Figure 3A.

Example 4 - (0.2/0.6 Pt/Pd) Catalyst prepared by muller addition and Expanded Trilobe insert

[0037] 65 parts (basis: calcined 538°C) of once-calcined MCM-41 crystals (with SiAh ~ 50/1) were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) and Pt/Pd precursor solutions in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" effective diameter expanded trilobe pieces of catalyst. The green extrudates were then dried in an oven at 121°C overnight. The dried extrudate was calcined in air at 500°C to decompose and remove residual carbon in the extrudate. The calcined extrudate comprised 0.19/0.60 wt% of Pt/Pd metals loading and exhibited a surface area of 713 m²/g after calcination. A photograph of the finished catalyst is shown in Figure 4A. Crush strength of green extrudates was 83.9 lbs/in. Uniformity of metal dispersion in extrudate pellets was studied by Electron Microprobe Analysis (EMPA). The Pt and Pd profiles along a line of a cross section of a number of pellets are shown in Figures 4B and 4C. Uniform metal dispersion across the cross section of a number of catalyst pellets was shown by EMPA and the consistency of metal content observed between different catalyst pellets is consistent with the uniformity of the coloring, particularly of the color saturation, among pieces of the catalyst shown in Figure 4A.

Examples 5A and 5B - (0.3/0.9 Pt/Pd) Catalyst prepared by muller addition and Expanded Trilobe insert at 450°C and at 500°C

[0038] 65 parts (basis: calcined 538°C) of once-calcined MCM-41 crystals (with SiAk ~ 50/1) were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) and Pt/Pd precursor solutions in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" effective diameter expanded trilobe pieces of catalyst. The green extrudates were then dried in an oven at 121°C overnight. The dried extrudates were calcined in air at 450°C (Example 5A) and 500°C (Example 5B) to decompose and remove residual carbon in the extrudate. The calcined extrudates comprised 0.29/0.85 and 0.3/0.91 wt% of Pt/Pd metals coating and exhibited a surface area of 708 and 757 m²/g for samples of Example 5 A and Example 5B, respectively, after calcination. A photograph of the green and finished catalyst is shown in Figure 5. Metal dispersion in the extrudate is very uniform based on the uniformity of the coloring, particularly of the color saturation, among the catalyst pellets shown in Figure 5. Crush strength of green extrudates was 83 lbs/in.

Examples 6A and 6B - (0.3/0.9 Pt/Pd) Catalyst prepared by muller addition and Cylinder insert at 450°C (6A) and 500°C (6B)

[0039] 65 parts (basis: calcined 538°C) of once-calcined MCM-41 crystals (with SiAk ~ 50/1 were mixed with 35 parts of pseudoboehmite alumina (Versal™-300, basis: calcined 538°C) and Pt/Pd precursor solutions in a muller. Sufficient water was added to produce an extrudable paste. The paste was extruded on an extruder to form 1/16" diameter cylindrical pieces of catalyst. The green extrudates were then dried in an oven at 121°C overnight. The dried extrudate was calcined in air at 450°C (Example 6A) and 500°C (Example 6B) to decompose and remove residual carbon in the extrudate. The calcined extrudates comprised 0.3/0.91 and 0.3/0.86 wt% of Pt/Pd metals coating and exhibited a surface area of 722 and 757 m²/g for samples from Example 6A and from Example 6B after calcination. Photos of the finished catalysts are shown in Figures 6A and 6B. Metal dispersion in the extrudates is very uniform based on the uniformity of the coloring, particularly of the color saturation, among the catalyst pellets shown in Figure 6. Crush strength of green extrudates was 105.3 lbs/in.

Example 7 - Activity evaluation

[0040] Catalysts from reference Example 1, Example 6A and Example 6B were tested for aromatics saturation activity in a HiP-Hoss screening unit. Results are shown in Table 1 below. Example 6A of showed about ~ 17 % higher activity than the reference Example 1.

Table 1 : Aromatics saturation activity of selected catalyst materials

Table 2: Feed composition - Example 7

Property

Total 367.9

Aromatics mmol/kg

(TA)

2+ Ring 53.5 mmol/kg

Aromatics

Polar 49.8 mmol/kg

Aromatics

Sulfur by 0.0073 mass%

Xray

Nitrogen < 5 ppm

Density 0.86 g/ml

API 30.37 Aromaticity 3.6%

Pour Point -7 °C

Cloud Point 1 °c

Example 8 - Activity evaluation

[0041] The catalyst of Example 6A was also compared to the reference Example 1 in a flow unit using a lube range feed with 18.7 wt% aromatics, 12 ppm nitrogen, and 58 ppm sulphur with a LHSV of 8.6 and gas to oil (GTO) ratio of 400.

[0042] Results are shown in Figure 7. The sample of Example 6A (muller metals Al-MCM-41) has a significantly higher aromatic saturation activity than the sample of Example 1 (Al-MCM- 41). In addition, at the temperature of 350 °C where the aromatic saturation activity was identical due to thermodynamic equilibrium, the catalyst of Example 6A had a 22% lower 700 °F+ conversion than the catalyst of Example 1 (4.15% cf. 5.34%). This suggests that use of catalyst of Example 6A in aromatics saturation reactors can provide increased yield because of the lower cracking activity of the catalyst.

[0043] The description in this application is intended to be illustrative and not limiting of the invention. One in the skill of the art will recognize that variation in materials and methods used in the invention and variation of embodiments of the invention described herein are possible without departing from the invention. It is to be understood that some embodiments of the invention might not exhibit all of the advantages of the invention or achieve every object of the invention. The scope of the invention is defined solely by the claims following.

Claims

CLAIMS;

1. A method for producing a catalyst material comprising:

mixing a binder, a mesoporous silica/alumina material, water and one or more Pt or Pd precursors to form an extrudable paste;

extruding the paste to form a green catalyst extrudate; and drying to remove water, and calcining the extrudate to form a calcined extrudate catalyst material.

2. The method of claim 1, in which the mesoporous silica/alumina material is MCM-41.

3. The method of claim 2, in which the MCM-41 has a pore size from 1.5 to 8.0 nm.

4. The method of claim 1, in which at least one Pt precursor is a solution of platinum chloride or platinum tetraamine nitrate or at least one Pd precursor is palladium chloride or palladium tetraamine nitrate.

5. The method of claim 1, in which the calcining is performed under an oxidative atmosphere at a temperature of from 400-600 °C.

6. The method of claim 1, in which the binder is an alumina binder, a silica binder, a titania binder, a ceria binder, or a zirconia binder, or a mixture of any two or more of them.

7. The method of claim 1, in which the binder is an alumina binder having a

pseudoboehmite microstructure.

8. The method of claim 3, in which the binder is an alumina binder having a

pseudoboehmite microstructure.

9. The method of claim 4, in which the binder is an alumina binder having a

pseudoboehmite microstructure.

10. The method of claim 5, in which the binder is an alumina binder having a

pseudoboehmite microstructure.

11. A catalyst prepared by the method of claim 1, in which the calcined extrudate catalyst material contains of 0.01 - 10 wt% Pt and/or 0.01- 10 wt% Pd.

12. A catalyst prepared by the method of claim 1, in which the calcined extrudate catalyst material contains 0.1-0.3 wt% Pt and 0.2-1.0 wt% Pd and wherein the percentage of Pt is less than the percentage of Pd.

13. The catalyst of claim 12, in which the weight ratio of the amount of Pt to the amount of Pd is in a range of about 1 : 1 to 1 :5.

14. The catalyst of claim 11, in which the average amount of platinum and the average amount of palladium varies 25% or less among different pellets of a population of pellets of the catalyst.

15. The catalyst of claim 11 , in which the average amount of platinum varies by 25% or less between a 100 micron segment radial from the surface and a 100 micron segment of that radius spanning the center of the cross section of a piece of the catalyst and the average amount of palladium varies by 25% or less between a 100 micron segment radial from the surface and a 100 micron segment of that radius spanning the center of the cross section of a piece of the catalyst.

16. A method of hydrogenation of aromatic hydrocarbons comprising contacting said aromatic hydrocarbons with a catalyst of claim 11.

17. A method of hydrogenation of aromatic hydrocarbons comprising contacting said aromatic hydrocarbons with a catalyst of claim 12.

18. A method of hydrogenation of aromatic hydrocarbons comprising contacting said aromatic hydrocarbons with a catalyst of claim 15.