Hydrocarbon Synthesis Catalyst, Its Preparation Process and Its Use

Abstract

The present invention relates to catalysts, more particularly to a cobalt-containing catalyst composition. The present invention further relates to a process for preparing a cobalt-containing catalyst precursor, a process for preparing a cobalt-containing catalyst, and a hydrocarbon synthesis process wherein such a catalyst is used. According to a first aspect of the invention, there is provided a cobalt-containing catalyst composition comprising cobalt and/or a cobalt compound supported on and/or in a catalyst support; the catalyst composition also including a titanium compound on and/or in the catalyst support, and a manganese compound on and/or in the catalyst support.

Claims

1. A cobalt-containing catalyst composition comprising cobalt and/or a cobalt compound supported on and/or in a catalyst support; the catalyst composition also including a titanium compound on and/or in the catalyst support, and a manganese compound on and/or in the catalyst support.

2. The catalyst composition of claim 1 wherein the catalyst composition includes a dopant capable of enhancing the reducibility of the cobalt compound.

3. The catalyst composition of either one of claim 1 or 2 wherein the catalyst support is selected from the group consisting of alumina in the form of one or more aluminium oxides; silica (SiO.sub.2); titania (TiO.sub.2); magnesia (MgO); zinc oxide (ZnO); silicon carbide; and mixtures thereof.

4. The catalyst composition of claim 3 wherein the catalyst support is an alumina catalyst support or a silica (SiO.sub.2) catalyst support.

5. A process for preparing a cobalt-containing catalyst precursor, the process comprising introducing a cobalt compound onto and/or into a catalyst support; prior to and/or during and/or subsequent to introducing the cobalt compound onto and/or into the catalyst support, introducing a titanium compound onto and/or into the catalyst support; and prior to, and/or during, and/or subsequent to introducing the cobalt compound onto and/or into the catalyst support, introducing a manganese compound onto and/or into the catalyst support, thereby providing a cobalt-containing catalyst precursor.

6. The process of claim 5 wherein a dopant capable enhancing the reducibility of the cobalt compound is also introduced onto and/or into the catalyst support.

7. The process of either one of claim 5 or 6 wherein the catalyst support is selected from the group consisting of alumina in the form of one or more aluminium oxides; silica (SiO.sub.2); titania (TiO.sub.2); magnesia (MgO); zinc oxide (ZnO); silicon carbide; and mixtures thereof.

8. The process of claim 7 wherein the catalyst support is an alumina catalyst support or a silica (SiO.sub.2) catalyst support.

9. The process of any one of claims 5 to 8, wherein the process includes one or more calcination steps wherein the titanium and manganese compounds introduced onto and/or into the catalyst support are converted to titanium oxide and manganese oxide respectively.

10. The process of any one of claims 5 to 9 wherein the cobalt compound introduced onto and/or into the catalyst support is calcined thereby converting the cobalt compound into one more cobalt oxides.

11. The process of any one of claims 5 to 10 wherein the catalyst precursor includes more than 1 wt % and not more than 10 wt % Ti, based on the weight of the catalyst support (excluding the weight of the Ti), the Ti being present in the form of one or more titanium compounds.

12. The process of any one of claims 5 to 11 wherein the catalyst precursor includes more than 0.5 wt % and less than 10 wt % Mn, based on the weight of the catalyst support (excluding the weight of the Mn), the Mn being present in the form of one or more manganese compounds.

13. A process for preparing a cobalt-containing catalyst, the process includes preparing a cobalt-containing catalyst precursor as claimed in any one of claims 5 to 12; and reducing the catalyst precursor, thereby activating the catalyst precursor.

14. A hydrocarbon synthesis process which includes preparing a cobalt-containing catalyst as claimed in claim 13; and contacting hydrogen with carbon monoxide at a temperature above 100° C. and at a pressure of at least 10 bar with the catalyst, to produce hydrocarbons and optionally, oxygenates of hydrocarbons.

15. The process of claim 14 wherein the process includes a hydroprocessing step for converting the hydrocarbons and optionally oxygenates thereof to liquid fuels and/or other chemicals.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0170] The invention will now be described in more detail, by way of example only, with reference to the accompanying figures in which:

[0171] FIG. 1: is a graph showing the FT rate over Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9;

[0172] FIG. 2: is a graph showing methane selectivity over Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9; and

[0173] FIG. 3: is a graph depicting cumulative Al dissolution as a function of time for the Mn-modified, Ti-modified, MnTi-modified, unmodified alumina, Si—Al.sub.2O.sub.3 and MnSi—Al.sub.2O.sub.3 supports.

[0174] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of certain embodiments of the present invention by way of the following non-limiting examples.

EXAMPLES

[0175] The invention will now be described with reference to the following non-limiting experimental examples.

Example 1 (Comparative)—30 g Co/0.04 g Pt/100 g Un-Modified Al.SUB.2.O.SUB.3

[0176] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.04 g Pt/100 g support was prepared using an un-modified Al.sub.2O.sub.3 (Puralox with a surface area of 150 m.sup.2/g—hereinafter referred to as Puralox) support.

[0177] In a first impregnation step Co(NO.sub.3).sub.2.6H.sub.2O (79.0 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (0.026 g) were dissolved in distilled water (100 g). Carboxylic acid in the amount of about 0.03 moles/100 g support was dissolved in this solution. Puralox (100 g) was then added to this mixture and the excess water removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder.

TABLE-US-00001 TABLE 1 Drying profile for impregnated support Temperature (° C.) Pressure (mbar) Time (min) 60 250 15 75 250 30 85 250 30 85 250-130 120 85 130-50  15 85  50 180

[0178] The free flowing powder was then calcined in a fluidised bed calciner with a heating ramp rate of 1° C./min to 250° C. with a hold time of 6 hours, using a GHSV of 2.5 Nm.sup.3/kgCo(NO.sub.3).sub.2.6H.sub.2O/hour.

[0179] Then, in a second impregnation stage, the above steps were repeated using Co(NO.sub.3).sub.2.6H.sub.2O (56.8 g) and [Pt(NH.sub.4).sub.4(NO.sub.3).sub.2] (0.042 g) dissolved in water (100 g). The previously calcined material (100 g) was added to this mixture and the excess water removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder. The free flowing powder was then again calcined in a fluidised bed calciner with a heating ramp rate of 1° C./min to 250° C. with a hold time of 6 hours, using a GHSV of 2.5 Nm.sup.3/kgCo(NO.sub.3).sub.2.6H.sub.2O/hour.

Example 2 (Comparative)—30 g Co/0.04 g Pt/3.1 g Mn/100 Un-Modified Al.SUB.2.O.SUB.3 .(Mn as Promoter)

[0180] A cobalt based Fischer-Tropsch synthesis catalyst precursor was prepared as described in Example 1.

[0181] In this example, manganese was added as a catalyst promoter. After the second impregnation stage, Mn(NO.sub.3).sub.2.4H.sub.2O (10.1 g) was dissolved in water (100 g) and added to the calcined material (100 g). The excess water was removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder. The free flowing powder was then again calcined in a fluidised bed calciner with a heating ramp rate of 1° C./min to 250° C. with a hold time of 6 hours, using a GHSV of 2.5 Nm.sup.3/kgCo(NO.sub.3).sub.2.6H.sub.2O/hour.

Example 3 (Comparative)—Ti—Al.SUB.2.O.SUB.3 .(Puralox) Support (Ti as Modifier)

[0182] Titanium(IV)iso-propoxide (17.2 g) was added to dry ethanol (78.9 g) and allowed to mix for 10 minutes. Al.sub.2O.sub.3 (Puralox) (100 g) was added to this solution and allowed to mix for a further 10 minutes. Following this, the ethanol was removed under reduced pressure using the drying profile in Table 2 to obtain a free flowing powder.

TABLE-US-00002 TABLE 2 Drying profile for the Ti impregnated Puralox material Pressure (mbar) Temperature (° C.) Time (min) 842 60 10 500 60 30 400 60 30 300 60 30 200 60 60 100 60 60 50 60 60

[0183] After the drying step, the modified support was calcined in a fluidized bed calciner with a GHSV of 2.5 Nm.sup.3/kg support/hour using air as the calcination gas using a heating rate of 1° C./min to 425° C. with no hold step at this temperature. After this fluidised bed calcination step, the support material was calcined further in a muffle oven to 550° C. at a heating rate of 5° C./min and a final hold time of 5 hours. The resulting modified support included 2.6 g Ti/100 g Al.sub.2O.sub.3.

Example 4 (Comparative)—Mn—Al.SUB.2.O.SUB.3 .(Puralox) Support (Mn as Modifier)

[0184] Manganese(II)acetate tetrahydrate (13.8 g) was dissolved in water (80-100 g) and mixed for 10 minutes. Al.sub.2O.sub.3 (Puralox) (100 g) was added to this solution and mixed for a further 10 minutes. Following this, the water was removed under reduced pressure using the drying profile in Table 3 to obtain a free flowing powder.

TABLE-US-00003 TABLE 3 Drying profile for the Mn impregnated Puralox material Pressure (mbar) Temperature (° C.) Time (min) 100 85 60 50 85 180

[0185] After the drying step, the modified support was calcined in a fluidized bed calciner with a GHSV of 2.5 Nm.sup.3/hour/kg support using air as the calcination gas using a heating rate of 1° C./min to 425° C. with no hold step at this temperature. After this fluidised bed calcination step, the respective support material was calcined further in a muffle oven to 550° C. at a heating rate of 5° C./min and a final hold time of 5 hours. The resulting modified support included 3.1 g Mn/100 g Al.sub.2O.sub.3.

Example 5—MnTi—Al.SUB.2.O.SUB.3.(Puralox) Support (Mn and Ti as Modifiers)

[0186] The Ti—Al.sub.2O.sub.3 support obtained from Example 3, was impregnated with manganese(II)acetate tetrahydrate as described in Example 4. The resulting modified support included 2.6 g Ti/3.1 g Mn/100 g Al.sub.2O.sub.3.

Example 6 (Comparative)—30 g Co/0.075 g Pt/100 g Ti—Al.SUB.2.O.SUB.3 .(Ti as Modifier)

[0187] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/100 g support was prepared as described in Example 1, however, Ti—Al.sub.2O.sub.3 support as described in Example 3 was used.

Example 7 (Comparative)—30 g Co/0.075 g Pt/100 g Mn—Al.SUB.2.O.SUB.3 .(Mn as Modifier)

[0188] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/100 g support was prepared as described in Example 1. However, no carboxylic acid was added during catalyst preparation. Mn—Al.sub.2O.sub.3 support as described in Example 4 was used.

Example 8 (Inventive)—30 g Co/0.075 g Pt/100 g MnTi—Al.SUB.2.O.SUB.3.(Ti and Mn as Modifiers)

[0189] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/100 g support was prepared as described in Example 1. However, no carboxylic acid was added during catalyst preparation. MnTi—Al.sub.2O.sub.3 support as described in Example 5, was used.

Example 9 (Inventive)—30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—Al.SUB.2.O.SUB.3.(Ti as Modifier and Mn as Promoter)

[0190] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/3.1 g Mn/100 g support was prepared as described in Example 2, however, Ti—Al.sub.2O.sub.3 support as described in Example 3, was used.

Example 10 (Comparative)—30 g Co/0.04 g Pt/100 g Si—Al.SUB.2.O.SUB.3.(Si as Modifier)

[0191] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.04 gPt/100 g support was prepared as described in Example 1. 2.1 g Si/100 g Al.sub.2O.sub.3 support was used. TEOS (tetra ethoxy silane) was used as starting material for the support modification.

Example 11 (Comparative)—30 g Co/0.04 g Pt/3.1 g Mn/100 Si—Al.SUB.2.O.SUB.3.(Si as Modifier and Mn as Promoter)

[0192] A cobalt based Fischer-Tropsch synthesis catalyst precursor was prepared as described in Example 10. However, during the second impregnation stage, Co(NO.sub.3).sub.2.6H.sub.2O (56.8 g), [Pt(NH.sub.4).sub.4(NO.sub.3).sub.2] (0.042 g) and Mn(NO.sub.3).sub.2.4H.sub.2O (11.6 g) was dissolved in water (100 g) and added to the calcined material obtained in the first impregnation stage (100 g).

Example 12 (Comparative)—30 g Co/0.075 g Pt/100 g Ti—Al.SUB.2.O.SUB.3 .(Ti as Modifier)

[0193] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 gPt/100 g support was prepared as described in Example 1, however, no carboxylic acid was added during catalyst preparation. Ti—Al.sub.2O.sub.3 was used and was prepared as described in Example 3.

Example 13 (Comparative)—30 g Co/0.075 g Pt/100 g Ti—Al.SUB.2.O.SUB.3 .(Ti as Modifier)

[0194] A cobalt based Fischer-Tropsch synthesis catalyst precursor was prepared as described in Example 12. However, 5 g Ti/100 g Al.sub.2O.sub.3 support was used and was prepared as described in Example 3.

Example 14 (Comparative)—30 g Co/0.075 g Pt/100 g Ti—Al.SUB.2.O.SUB.3.(Ti as Modifier)

[0195] A cobalt based Fischer-Tropsch synthesis catalyst precursor was prepared as described in Example 12. However, 10 g Ti/100 g Al.sub.2O.sub.3 support was used and was prepared as described in Example 3.

Example 15—Reduction

[0196] The calcined catalyst precursors were reduced prior to Fischer-Tropsch synthesis using pure H.sub.2 flowing at 2.0 Nm.sup.3/kgCatalyst/hour at atmospheric pressure. The following heating profile was used, 1° C./min to 110° C. hold 3 hours followed with, 1° C./min to 425° C. hold 10 hours. The reduced catalyst was cooled down to room temperature and suspended into molten wax and loaded in a CSTR under an inert gas blanket (argon or nitrogen).

Example 16—Fischer-Tropsch Synthesis

[0197] The activated and wax protected catalysts, as described in Example 15, were tested for their slurry phase FTS performance in a laboratory micro slurry CSTR at a reactor temperature of 230° C. and a reactor pressure of about 22 bar during which a pure H.sub.2 and CO and Ar feed gas mixture was utilised with a ˜5% Ar content and a total feed molar H.sub.2/CO ratio of about 1.8. This reactor was electrically heated and sufficiently high stirrer speeds were employed as to eliminate any gas-liquid mass transfer limitations. The feed gas space velocity was changed such that the syngas conversion was around 78±1%. The water partial pressure was about 10 bar.

Discussion

Example 9 (Co/3.1 g Mn/100 g Ti—Al.SUB.2.O.SUB.3.) Showed Initial Catalyst Deactivation, However, after 5 Days On-Line the Catalyst Performance Stabilized and Remained Stable Over a 50 Day Period

[0198] FIG. 1 shows the percentage difference in FT rate for Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9 and can be calculated as (FT rate of Ex. 1, 2, 6-8, 10, 11 or 33—FT rate of Ex. 9)/FT rate of Ex. 9. As can be seen, Example 2 (Co/3.1 g Mn/100 g un-modified Al.sub.2O.sub.3) shows that the addition of manganese as catalyst promoter did not improve the activity stability of the catalyst relative to Example 1 (the un-promoted and un-modified catalyst sample), with time on-line. This trend was also observed in comparing catalysts containing the Si-modified Al.sub.2O.sub.3 support, promoted with manganese as in Example 11 (Co/3.1 g Mn/100 g Si—Al.sub.2O.sub.3) with Example 10 (Co/100 g Si—Al.sub.2O.sub.3).

[0199] However, Example 6 (Co/100 g Ti—Al.sub.2O.sub.3) and Example 7 (Co/100 g Mn—Al.sub.2O.sub.3) showed that titanium and manganese as Al.sub.2O.sub.3 support modifiers respectively, resulted in an enhancement in activity and activity stability relative to Example 1, the un-promoted and un-modified catalyst sample.

[0200] Turning to Example 7, this Example showed black wax, which is an indication of catalyst break-up. This was not observed for the catalysts containing the combination of titanium and manganese support modifications (Example 8, Co/100 g MnTi—Al.sub.2O.sub.3).

[0201] Even more surprisingly, the catalysts containing the combination of titanium and manganese, either manganese added as support modifier (Example 8) or catalyst promoter (Example 9), showed a significant enhancement in activity and activity stability relative to Examples 1, 2, 6, 7, 10 and 11.

[0202] The percentage difference in methane selectivity over the Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9, is shown in FIG. 2 and can be calculate as (% CH.sub.4 selectivity of Ex. 1, 2, 6-8, 10, 11 or 33-% CH.sub.4 selectivity of Ex. 9)/% CH.sub.4 selectivity of Ex. 9. As can be seen, Examples 8 and 9 containing the Mn/Ti combination showed lower and stable methane selectivity over time compared to the rest of the tested catalysts samples. Example 7, containing the Mn-modified Al.sub.2O.sub.3, showed initial low methane selectivity, which increased to the methane selectivity observed for Example 6, containing the Ti-modified Al.sub.2O.sub.3 support.

[0203] Table 4 below shows the FT performance over Examples 12-14 relative to the initial activities. These samples were prepared using Ti-modified Al.sub.2O.sub.3 with varying levels of Ti modification. As can be seen, increasing the Ti content from 2.6 g Ti/100 g Al.sub.2O.sub.3 to 10 g Ti/100 g Al.sub.2O.sub.3 did not result in a relative improvement in activity stability of the catalysts compared to that of Example 12. The catalysts containing the higher loading Ti resulted in lower activity stability with time on-line.

TABLE-US-00004 TABLE 4 The relative FT rate.sup.1 over Examples 12-14 tested under conditions as described in Example 16 Example 12, Example 13, Example 14, Time on-stream, 2.6 g Ti/100 g (5 g (10 g days Al.sub.2O.sub.3) Ti—Al.sub.2O.sub.3) Ti—Al.sub.2O.sub.3) 1 1 1 1 19 0.53 0.38 0.37 .sup.1Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) and Error is 5% e.g. 1 ± 0.05

Example 17—Fischer-Tropsch Synthesis

[0204] The activated and wax protected catalysts, as described in Example 15, for Examples 8 and 9 were tested for their slurry phase FTS performance in a laboratory micro slurry CSTR at a reactor temperature of 230° C. and a reactor pressure of about 19 bar during which a pure H.sub.2, CO and Ar feed gas mixture was utilised with a 10% Ar content and a total feed molar H.sub.2/CO ratio of ˜1.5.

[0205] This reactor was electrically heated and sufficiently high stirrer speeds were employed as to eliminate any gas-liquid mass transfer limitations. The feed gas space velocity was changed such that the syngas conversion was around 72±1%. The water partial pressure was about 6 bar.

[0206] Examples 8 and 9 were tested under the conditions described in Example 17. As can be seen from Table 5, Example 8, containing the MnTi support modification and Example 9 (containing Mn as promoter and Ti as support modifier) showed comparable relative FT activities and methane selectivities with time on-line, showing the beneficial effect of the combination of MnTi and adding Mn as catalyst promoter or support modifier under the FT conditions.

TABLE-US-00005 TABLE 5 FT performance over Examples 8 and 9 with time on- line under conditions as described in Example 17 Time on-stream, Relative FT Relative days rate.sup.1 CH.sub.4 selectivty.sup.2 Example 8, Co/MnTi—Al.sub.2O.sub.3 1 1 1 9 0.8 0.88 30 0.71 0.86 Example 9, CoMn/Ti—Al.sub.2O.sub.3 1 1 1 8 0.78 0.89 30 0.67 0.84 .sup.1Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) and Error is 5% e.g. 1 ± 0.05 .sup.2Drift in % CH.sub.4 selectivity relative to day 1; C % excluding CO.sub.2 formation and Error is 0.3 percentage points, e.g. 5.8 ± 0.3

Example 18 (Comparative)—30 g Co/0.075 g Pt/100 g Mn—Al.SUB.2.O.SUB.3

[0207] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 gPt/100 g support was prepared as described in Example 1. However, no carboxylic acid was added during catalyst preparation. Mn—Al.sub.2O.sub.3 support as described in Example 4 was used. However, the resulting modified support consisted of 2.1 g Mn/100 g Al.sub.2O.sub.3.

Example 19 (Comparative)—30 g Co/0.075 g Pt/100 g Mn-Al.SUB.2.O.SUB.3

[0208] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/100 g support was prepared as described in Example 1. However, no carboxylic acid was added during catalyst preparation. Mn—Al.sub.2O.sub.3 support as described in Example 4 was used. However, the resulting modified support consisted of 7.5 g Mn/100 g Al.sub.2O.sub.3.

Example 20 (Comparative)—30 g Co/0.075 g Pt/100 g Mn-Al.SUB.2.O.SUB.3

[0209] A cobalt based Fischer-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/100 g support was prepared as described in Example 1. However, no maleic acid was added during catalyst preparation. Mn—Al.sub.2O.sub.3 support as described in Example 4 was used. However, the resulting modified support consisted of 10 g Mn/100 g Al.sub.2O.sub.3.

Example 21—Fischer-Tropsch Synthesis

[0210] The activated and wax protected catalysts, as described in Example 15, for Examples 18-20 were tested for their slurry phase FTS performance in laboratory micro slurry CSTR. The pressure was increased to 18 bar and the temperature to 230° C., where after the synthesis was introduced.

[0211] The synthesis feed gas consisted of hydrogen, carbon monoxide and it contained 10% argon as an internal standard with a total feed molar H.sub.2/CO ratio of ˜1.6. This reactor was electrically heated and sufficiently high stirrer speeds were employed so as to eliminate any gas-liquid mass transfer limitations. The % H.sub.2+CO conversion were maintained at 60%±2, by controlling the feed flow by means of Brooks mass flow controllers. The water partial pressure was about 5 bar.

[0212] Table 6 shows the relative FT performance over Examples 18-20. These samples were prepared using Mn-modified Al.sub.2O.sub.3 with varying levels of Mn modification. No beneficial effect was observed with the increased Mn content from 2.1 g Mn/100 g Al.sub.2O.sub.3 to 10 g Mn/100 g Al.sub.2O.sub.3. An increase in Mn levels resulted in a significant drift (decrease) in the FT rates with time on-stream.

TABLE-US-00006 TABLE 6 The relative FT rate.sup.1 over Examples 18-20 tested under conditions as described in Example 21 Example 18, Example 19, Example 20, Time on-line, (2.1 g Mn/100 g (7.5 g Mn/100 g (10 g Mn/100 g days Al.sub.2O.sub.3) Al.sub.2O.sub.3) Al.sub.2O.sub.3) 1 1 1 1 5 0.94 0.72 0.45 .sup.1Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) and Error is 5% e.g. 1 ± 0.05

Example 22 (Comparative)—MnSi—Al.SUB.2.O.SUB.3 .(Puralox) Support

[0213] The Si—Al.sub.2O.sub.3 support as described in Example 10 was impregnated with manganese(II)acetate tetrahydrate as described in Example 4. The resulting modified support consisted of 3 g Mn/100 g SiAl.sub.2O.sub.3.

Example 23 (Comparative)—MnSi—Al.SUB.2.O.SUB.3 .(Puralox) Support

[0214] The Si—Al.sub.2O.sub.3 support as described in Example 10 was impregnated with manganese(II)acetate tetrahydrate as described in Example 4. The resulting modified support consisted of 5 g Mn/100 g Si—Al.sub.2O.sub.3.

Example 24 (Conductivity Measurements)

[0215] Alumina dissolves in an aqueous medium at low pH. The dissolution of alumina results in the formation of aluminium ions. As more and more alumina dissolves, the concentration of aluminium increases with time. An increase in aluminium with time was followed by monitoring the conductivity at a constant pH of 2. The pH was kept constant by automated addition of a 10% nitric acid solution. The results are given in FIG. 3 for the modified and un-modified Al.sub.2O.sub.3.

[0216] The Ti (Example 3), Mn (Example 4) and Si modified Al.sub.2O.sub.3 supports exhibited very similar Al-dissolution behaviour over time. The MnSi modification of the Al.sub.2O.sub.3 (Example 22) resulted in a decrease in the Al-dissolution. However, a further increase in the Mn loading (Example 23) negated the suppression of the Al-dissolution and resulted in the Al-dissolution behaviour similar to the Si-modified Al.sub.2O.sub.3 support. Surprisingly, it can be seen that over the MnTi-modified support (Example 5) the Al-dissolution was significantly suppressed relative to the MnSi modified Al.sub.2O.sub.3 (Example 22).

Example 25 (Inventive)—30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 g Ti/100 g Al.SUB.2.O.SUB.3.) (Co-Hydrolysis, Ti as Modifier and Mn as Promoter), C4639

[0217] A cobalt based Fisher-Tropsch synthesis catalyst precursor with the composition 30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 g Ti/100 g Al.sub.2O.sub.3) was prepared as described in Example 9, however the Ti—Al.sub.2O.sub.3 support used in Example 9 was replaced with a titanium-containing support that was prepared via co-hydrolysis of titanium (IV) 2-ethylhexoxide and Al-hexanolate as described in Example 37 of WO2014020507.

Example 26 (Inventive)—30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 g Ti/100 g Al.SUB.2.O.SUB.3 .(Calcined PURAL 200™ as the Support, Ti as Modifier and Mn as Promoter), C4685

[0218] A cobalt based Fisher-Tropsch synthesis catalyst precursor was prepared with the composition 30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 g Ti/100 g Al.sub.2O.sub.3) as described in Example 9, however, the Puralox used in Example 9 was replaced with calcined PURAL 200™ which has a pore diameter similar to the pore diameter of the support of Example 25 and has a surface area of about 90 m.sup.2/g.

Example 27—Reduction and Fischer-Tropsch Synthesis (FTS)

[0219] The calcined catalyst precursors of Examples 25 and 26 were reduced and suspended into molten wax as described in Example 15. The FTS performance of the activated and wax protected catalysts of Examples 25 and 26 were evaluated in a fix bed reactor at 230° C. and a reactor pressure of about 16 bar utilizing a feed gas mixture with an inlet molar H.sub.2/CO ratio of about 1.6. The feed gas space velocity was changed such that the syngas conversion was ˜62%-65%.

Discussion

[0220] Table 7 shows that similar FTS catalyst performance results were obtained in comparing the Co/Pt/Mn/Ti—Al.sub.2O.sub.3 catalyst sample prepared via co-hydrolysis of the Ti-modified support (Example 25) with Example 26 (slurry impregnation of Ti), demonstrating that co-hydrolysis of the Ti-modified support is an alternative to slurry impregnation of titanium on alumina.

TABLE-US-00007 TABLE 7 FT performance over Examples 25 and 26 under conditions as described in Example 27 CH.sub.4 selectivity.sup.1 Example 25, Example 26, % difference in C4639.sup.2 C4685.sup.2 absolute CH.sub.4 Co/Pt/Mn/ Co/Pt/Mn/ selectivity Time on-line, Ti—Al.sub.2O.sub.3 with Ti—Al.sub.2O.sub.3 with between Ex 25 days co-hydrolysis slurry impregnation and Ex 26.sup.3 1 1.00 1.00 0.06 2 1.00 1.02 0.03 3 1.01 1.01 0.07 7 1.05 % difference in absolute FT rates between Relative FT rate.sup.4 Ex 25 and Ex 26.sup.5 1 1.00 1.00 0.14 2 0.97 0.97 0.15 3 0.93 0.94 0.13 7 0.88 .sup.1C % excluding CO.sub.2 formation .sup.2Drift in % CH.sub.4 selectivity relative to day 1 .sup.3% CH.sub.4 selectivity (sel) difference between C4639 and C4685 = (% CH.sub.4 sel of C4639 − % CH.sub.4 sel of C4685)/% CH.sub.4 sel of C4685 .sup.4Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) .sup.5% difference in FT rates between C4639 and C4685 = (FT rate of C4639 − FT rate of C4685)/FT rate of C4685

Example 28: (Comparative)—30 g Co/0.075 g Pt/5 g Ni/100 g (2.6 q Ti/100 g Al.SUB.2.O.SUB.3.) (Ti as Modifier and Ni as Promoter), C4140

[0221] Co(NO.sub.3).sub.2.6H.sub.2O (11.9 g), (NH.sub.3).sub.4Pt(NO.sub.3).sub.2 (0.0075 g) and Ni(NO.sub.3).sub.2.6H.sub.2O (1.9 g) were dissolved in water (13 ml for Co, 2 ml for Pt, 2 ml for Ni). The pH of the solution was adjusted to 2.3. 15 g of the Ti-modified Puralox support as described in Example 3 was added and the excess water removed under reduced pressure using the drying profile in Table 8 to obtain a free flowing powder.

TABLE-US-00008 TABLE 8 Drying profile Pressure (mbar) Temperature (° C.) Time (min) Atmospheric 60 10 280 60 30 280 75 90 280 85 60 50 85 60 50 90 120

[0222] 20 g of the free flowing sample was calcined in a vertical furnace using an air flow of 1000 ml/min and a heating rate of 1° C./min to 250° C. with a hold time of 6 hours. The above steps were repeated in a second impregnation stage by dissolving Co(NO.sub.3).sub.2.6H.sub.2O (6.8 g), (NH.sub.3).sub.4Pt(NO.sub.3).sub.2 (0.01 g) and Ni(NO.sub.3).sub.2.6H.sub.2O (1.2 g) in water (9 ml for Co, 2 ml for Pt, 3 ml for Ni). The previously calcined (first impregnation stage) material (12 g) was added to the mixture and the excess water removed under reduced pressure using the drying profile in Table 8. 15 g of the free flowing sample was calcined in a vertical furnace using an air flow of 750 ml/min and a heating rate of 1° C./min to 250° C. with a hold time of 6 hours.

Example 29: (Inventive)—30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 g Ti/100 g Al.SUB.2.O.SUB.3.) (Ti as Modifier and Mn as Promoter—Similar to Example 9, but with Smaller Quantities and Different Drying Profile), C4144

[0223] Co(NO.sub.3).sub.2.6H.sub.2O (13.3 g) and (NH.sub.3).sub.4Pt(NO.sub.3).sub.2 (0.0075 g) were dissolved in water (13 ml for Co, 3 ml for Pt). The pH of the solution was adjusted to 2.3. 15 g of the Ti-modified Puralox support as described in Example 3 was added and the excess water removed under reduced pressure using the drying profile in Table 9 to obtain a free flowing powder.

TABLE-US-00009 TABLE 9 Drying profile Pressure (mbar) Temperature (° C.) Time (min) Atmospheric 60 10 280 60 30 250 75 30 250 85 30 250-130 85 120 gradient 130-50  85  15 gradient  50 85 180 

[0224] 20 g of the free flowing sample was calcined in a vertical furnace using an air flow of 1000 ml/min and a heating rate of 1° C./min to 250° C. with a hold time of 6 hours. In a second impregnation stage, the above steps were repeated using Co(NO.sub.3).sub.2.6H.sub.2O (5.75 g) and (NH.sub.3).sub.4Pt(NO.sub.3).sub.2 (0.01 g) as well as Mn(NO.sub.3).sub.2.4H.sub.2O (1.4 g) by dissolving it in water (10 ml for Co, 2 ml for Pt, 3 ml for Mn). 12 g of the first impregnation stage calcined material was added to the mixture and the excess water was removed under reduced pressure using the drying profile of Table 9 to obtain a free flowing powder. 15 g free flowing sample was calcined in a vertical furnace using an air flow of 750 ml/min and a heating rate of 1° C./min to 250° C. with a hold time of 6 hours.

Example 30—Reduction and Fischer-Tropsch Synthesis (FTS)

[0225] The calcined catalyst precursors of Examples 28 and 29 were reduced and suspended into molten wax as described in Example 15. The FTS performance of the activated and wax protected catalysts of Examples 28 and 29 were evaluated in a fix bed reactor at 230° C. as described in Example 27.

Discussion

[0226] It is known that nickel can be a used as an activity stability promoter [Ind. Eng. Chem. Res. 2010, 49, 4140-4148 and U.S. Pat. No. 8,143,186]. However, the addition of Ni as promoter to the Co/Pt/Ti—Al.sub.2O.sub.3 FTS catalyst did not demonstrate the same Co FTS catalyst performance as when Mn was used as promoter. Mn as promoter resulted in lower methane selectivity with higher activity compared to Ni as promoter. Table 10 illustrates the extent of deactivation of the catalysts as described in Example 28 and Example 29 relative to its initial activity as well as the drift in methane selectivity obtained over catalysts as prepared in Example 28 and 29 and activated and tested as described in Example 30 relative to its initial methane selectivity.

TABLE-US-00010 TABLE 10 FTS performance over Example 28 (Co/Pt/Ni//Ti—Al.sub.2O.sub.3) and Example 29 (Co/Pt/Mn/Ti—Al.sub.2O.sub.3) with time-on-line_under conditions as described in Example 30 CH.sub.4 selectivity.sup.1 Example 28, Example 29, % difference in C4140.sup.2 C4144.sup.2 absolute CH.sub.4 Time on-line, Co/Pt/Ni/ Co/Pt/Mn/ selectivity between days Ti—Al.sub.2O.sub.3 Ti—Al.sub.2O.sub.3 Ex 28 and Ex 29.sup.3 1 1.00 1.00 0.78 3 0.94 1.03 0.64 5 0.93 1.04 0.59 10 1.04 % difference in absolute FT rates between Relative FT rate.sup.4 Ex 28 and Ex 29.sup.5 1 1.00 1.00 −0.27 3 1.10 0.93 −0.14 5 1.17 0.92 −0.08 10 0.88 .sup.1C % excluding CO.sub.2 formation .sup.2Drift in % CH.sub.4 selectivity relative to day 1 .sup.3% CH.sub.4 selectivity (sel) difference between C4140 and C4144 = (% CH.sub.4 sel of C4140 − % CH.sub.4 sel of C4144)/% CH.sub.4 sel of C4144 .sup.4Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) .sup.5% difference in FT rates between C4140 and C4144 = (FT rate of C4140 − FT rate of C4144)/FT rate of C4144

Example 31: (Inventive)—30 g Co/0.075 g Pt/3.1 g Mn/100 g (2.6 q Ti/100 Al.SUB.2.O.SUB.3.) with Ti as Modifier and Mn as Promoter Using Ahydrothermal Deposition Method (HDM), C4585

[0227] Co(NO.sub.3).sub.2.6H.sub.2O (37.2 g), (NH.sub.3).sub.4Pt(NO.sub.3).sub.2 (0.07 g), Mn(NO.sub.3).sub.2.4H.sub.2O (7.06 g) and carboxylic acid (1.25 g) were dissolved in 75 ml water. Cobalt hydroxide (3 g) was added to the nitrate solution where after 50 g of the Ti-modified Puralox support as described in Example 3 was added. An additional 3 g of Co(OH).sub.2 was added to the slurry and mixed at 95° C. in a rotary evaporator at 65 rpm. Additional 3 g of Co(OH).sub.2 was added until the desired loading of 11.8 g was reached. The mixture was stirred until complete absorption of Co(OH).sub.2 (for approximately 3 hours). The excess water was removed under reduced pressure using the drying profile of Table 11 to obtain a free flowing powder and calcined at 250° C. at a heating rate of 1° C./min in air (2500 ml/min/gcat) for 6 hours.

TABLE-US-00011 TABLE 11 Drying profile Pressure (mbar) Temperature (° C.) Time (min) 500-130 95 180 50 100 120

[0228] The calcined catalyst precursor was reduced and suspended into molten wax as described in Example 15. The catalyst was tested for its slurry phase FTS performance in a laboratory micro slurry CSTR as described in Example 17.

[0229] As can be seen from Table 12, Example 31, prepared using HDM, showed lower methane selectivity and higher activity when comparing the absolute CH.sub.4 selectivity and reaction rates with Example 9 (the cobalt nitrate slurry impregnation method). The drift in methane selectivity of Example 31 is slightly more than Example 9, but the deactivation relative to day 1 over time on stream of Example 31 and Example 9 are comparable.

TABLE-US-00012 TABLE 12 FTS performance over Example 31 (Co/Pt/Mn/Ti—Al.sub.2O.sub.3 - prepared using HDM) with time-on-line under conditions as described in Example 17) CH.sub.4 selectivity.sup.1 Example 31, % difference in C4585.sup.2 Example 9, absolute CH.sub.4 Co/Pt/Mn/ C2155.sup.2 selectivity Time on-line, Ti—Al.sub.2O.sub.3 Co/Pt/Mn/ between Ex 31 and days (HDM) Ti—Al.sub.2O.sub.3 Ex 9.sup.3 1 1.00 1.00 −0.15 17 0.85 0.89 −0.19 31 0.76 0.86 −0.26 % difference in absolute FT rates between Relative FT rate.sup.4 Ex 31 and Ex 9.sup.5 1 1.00 1.00 0.21 17 0.66 0.70 0.15 31 0.66 0.70 0.15 .sup.1C % excluding CO.sub.2 formation .sup.2Drift in % CH.sub.4 selectivity relative to day 1 .sup.3% CH.sub.4 selectivity (sel) difference between C4585 and C2155 = (% CH.sub.4 sel of C4585 − % CH.sub.4 sel of C2155)/% CH.sub.4 sel of C2155 .sup.4Relative to the initial FT rate ((CO + CO.sub.2) μmol/CO/gs)) .sup.5% difference in FT rates between C4585 and C2155 = (FT rate of C4585 − FT rate of C2155)/FT rate of C2155

Example 32: MnTi—SiO.SUB.2 .(Mn and Ti as Support Modifiers on a Silica Support)

[0230] Titanium (IV)iso-propoxide (17.2 g) was added to dry ethanol (78.9 g) and allowed to mix for 10 minutes. Amorphous, preshaped silica-gel (100 g), CARiACT Q-15, as obtained from Fuji Silysia, was added to this solution and allowed to mix for a further 10 minutes. The ethanol was removed under reduced pressure using the drying profile in Table 2 to obtain a free flowing powder.

[0231] Manganese(II)acetate tetrahydrate (13.8 g Mn(Ac).sub.2.4H.sub.2O for 3.1 g Mn loading) was dissolved in water (80-100 g) and allowed to mix for 10 minutes. The free flowing powder obtained from the Ti(OPr).sub.4 modified silica (100 g) was added to this solution and allowed to mix for a further 10 minutes. The water was removed under reduced pressure using drying profile in Table 3 to obtain a free flowing powder. After the drying step, the modified support was calcined in a fluidised bed with a GHSV of 2.5 Nm.sup.3/kg support/hour using air as calcination gas at a heating rate of 1° C./min to 425° C. The support material was further calcined in a muffle oven to 500-550° C. at a heating rate of 5° C./min and a final hold time of 5 hours. The resulting modified support included 3.1 g Mn/2.6 g Ti/100 g SiO.sub.2.

Example 33: (Inventive)—30 g Co/0.075 g Pt/100 g (3.1 g Mn/2.6 g Ti/100 SiO.SUB.2.) (Mn and Ti as Support Modifiers), C4859

[0232] In a first impregnation step, Co(NO.sub.3).sub.2.6H.sub.2O (39.5 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (0.025 g) were dissolved in water (50 g). The pH of the solution was adjusted to 2.3 using diluted nitric acid. The MnTi—SiO.sub.2 (50 g) support as described in Example 32 was added to the mixture and the excess water removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder. The free flowing powder was calcined in a fluidized bed calciner with a heating ramp rate of 1° C./min to 250° C. with a hold time of 6 hours using a GHSV of 2500 Nm.sup.3/kg(Co(NO.sub.3).sub.2.6H.sub.2O)/hour.

[0233] In a second impregnation step, Co(NO.sub.3).sub.2.6H.sub.2O (28.4 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (0.04 g) were dissolved in water (50 g). The pH of the solution was adjusted to 2.3 using diluted nitric acid. The calcined material of the first impregnation step (50 g) was then added to this mixture and the excess water was removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder. The free flowing powder was calcined in a fluidized bed calciner with a heating ramp rate of 1° C./min to 250° C. with a hold time of 6 hours using a GHSV of 2500 Nm.sup.3/kg(Co(NO.sub.3).sub.2.6H.sub.2O)/hour.

[0234] The calcined catalyst material was reduced and suspended into molten wax as described in Example 15. The catalyst was tested for its slurry phase FTS performance in a laboratory micro slurry CSTR as described in Example 17.

Discussion

[0235] As mentioned before, FIG. 1 shows the percentage difference in FT rate for Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9. The Mn/Ti combination on a silica support (Example 33) also demonstrated a significant enhancement in activity and activity stability compared to the comparative examples.

[0236] As mentioned before, FIG. 2 shows the relative (percentage difference in) methane selectivity for Examples 1, 2, 6-8, 10, 11 and 33 relative to Example 9. Example 33 containing the Mn/Ti combination on a silica support showed the lowest methane selectivity over time compared to the rest of the tested catalysts samples.