PROCESS FOR PREPARING A COBALT-CONTAINING CATALYST PRECURSOR AND PROCESS FOR HYDROCARBON SYNTHESIS

Abstract

The invention provides a process for preparing a cobalt-containing catalyst precursor. The process includes calcining a loaded catalyst support comprising a silica (SiO.sub.2) catalyst support supporting cobalt nitrate to convert the cobalt nitrate into cobalt oxide. The calcination includes heating the loaded catalyst support at a high heating rate, which does not fall below 10° C./minute, during at least a temperature range A. The temperature range A is from the lowest temperature at which calcination of the loaded catalyst support begins to 165° C. Gas flow is effected over the loaded catalyst support during at least the temperature range A. The catalyst precursor is reduced to obtain a Fischer-Tropsch catalyst.

Claims

1. A process for preparing a cobalt-containing catalyst precursor, which process includes calcining a loaded catalyst support comprising a silica (SiO.sub.2) catalyst support supporting cobalt nitrate, the calcination of the loaded catalyst support comprising converting the cobalt nitrate into cobalt oxide; and the calcination including heating the loaded catalyst support at a high heating rate which does not fall below 10° C./minute during at least a temperature range A which is from the lowest temperature at which the calcination of the loaded catalyst support begins to 165° C. and wherein gas flow is effected over the loaded catalyst support during at least the temperature range A at a gas hourly space velocity (GHSV) of at least 5 Nm.sup.3/kg cobalt nitrate/hour, the lowest temperature at which calcination of the loaded catalyst support begins being the temperature at which cobalt nitrate begins to decompose to release NO.sub.2 gas in excess of 1500 ppm(v) as measured by means of FTIRS with gas phase analysis at a heating rate of 0.5° C./min in a He gas mixture containing 12% 02 gas flow rate of (0.5 ml/s), thereby to produce the cobalt-containing catalyst precursor.

2. The process of claim 1 wherein the silica (SiO.sub.2) catalyst support is porous and has an average pore diameter of more than 20 nm but less than 50 nm, the average pore diameter being determined by means of Barrett-Joyner-Halenda (BJH) nitrogen physisorption analysis.

3. The process of claim 1 the loaded catalyst support includes both a titanium compound on and/or in the catalyst support and a manganese compound on and/or in the catalyst support.

4. The process of claim 1 wherein the loaded catalyst support includes cobalt hydroxide (Co(OH).sub.2) in addition to the cobalt nitrate.

5. The process of claim 1 wherein the loaded catalyst support includes a dopant capable of enhancing the reducibility of a cobalt nitrate after calcination thereof, the dopant being in the form of a dopant compound which is a compound of a metal selected from the group including palladium (Pd), platinum (Pt), ruthenium (Ru), rhenium (Re) and a mixture of two or more thereof.

6. The process of claim 1 wherein the calcination includes heating the loaded catalyst support to a temperature above the temperature range A.

7. The process of claim 1 wherein the calcination includes heating the loaded catalyst support at a high heating rate which does not fall below 10° C./minute during at least a temperature range which is from 100° C. to 170° C.

8. The process of claim 7 wherein the calcination includes heating the loaded catalyst support at a high heating rate which does not fall below 10° C./minute during at least a temperature range which is from 100° C. to 220° C.

9. The process of claim 1 wherein the gas flow that is effected over the loaded catalyst support during the temperature range A is at a gas hourly space velocity (GHSV) of at least 9 Nm.sup.3/kg cobalt nitrate/hour.

10. The process of claim 1 wherein the calcination is carried out in a fluidised bed calciner.

11. The process of claim 1 which includes drying the loaded catalyst support prior to calcining the loaded catalyst support at the high heating rate during the temperature range A.

12. A process for preparing a cobalt-containing catalyst, the process comprising preparing a cobalt-containing catalyst precursor as claimed in claim 1; and reducing the catalyst precursor, thereby activating the catalyst precursor and obtaining the catalyst.

13. A hydrocarbon synthesis process for producing hydrocarbons or oxygenates of hydrocarbons, which process includes preparing a cobalt-containing catalyst according to the process as claimed in claim 12; and the process also including contacting the said catalyst with hydrogen and carbon monoxide at a temperature above 100° C. and at a pressure of at least 10 bar to produce hydrocarbons or oxygenates of hydrocarbons.

14. The hydrocarbon synthesis process of claim 13 which includes a hydroprocessing step for converting the hydrocarbons or oxygenates thereof to liquid fuels and/or other chemicals.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0087] The invention will now be described in more detail, by way of example only, with reference to the accompanying figures in which:

[0088] FIG. 1 shows a plot of low heating rate fluidized bed calcination temperature, bed height, bed dP & NO.sub.2 concentration in respect of Example 1;

[0089] FIG. 2 shows a plot of high heating rate fluidized bed calcination temperature, bed height, bed dP and NO.sub.2 concentration in respect of Example 4;

[0090] FIG. 3 shows a 1 hour period enlargement of the calcination profile of FIG. 2;

[0091] FIG. 4 shows a plot of % difference in FTS rates in respect of examples 1, 7, 10, 11, 12, 13, 15 and 30 with reference to that of Example 4;

[0092] FIG. 5 shows a plot of turbidity as a function of reactor temperature in respect of examples 15 to 19 and 21;

[0093] FIG. 6 shows a plot of % difference in FTS rates from Example 20 as a function of reactor temperature in respect of examples 16 to 22;

[0094] FIG. 7 shows a TPO profile in respect of Example 28; and

[0095] FIG. 8 shows a TPO profile in respect of Example 29.

[0096] 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

Definitions Relevant to the Examples

[0097] Semi-continuous feeding of the loaded catalyst support: The loaded catalyst support is fed into the calciner continuously or in a number of batches where the feed is combined (forming a bed) and held for a holding period. The combined feed is then unloaded in batch mode (preferably a single batch) after the holding period in the calciner.

[0098] Gas hourly space velocity (GHSV): For typical calcination of a loaded catalyst support supporting Co(NO.sub.3).sub.2.6H.sub.2O, the GHSV (gas hour space velocity) is defined as m.sub.n.sup.3.sub.air/h/kg.sub.Co(NO3)2.6H2O and is calculated from the air flow (m.sub.n.sup.3/h) (or air may be replaced with other suitable gas) divided by the total amount of Co(NO.sub.3).sub.2.6H.sub.2O loaded for a specific catalyst amount or batch. However, during semi-continuous feeding, a flow (kg/h) loaded catalyst support is effected instead of loading a full batch before starting with the calcination. In such a case the amount of Co(NO.sub.3).sub.2.6H.sub.2O used for expressing the GHSV is the amount of Co(NO.sub.3).sub.2.6H.sub.2O fed into the calciner in one hour. That is, if the gas flow is 20 Nm.sup.3 per hour and 2 kg cobalt nitrate is fed in an hour, then the gas flow of 20 Nm.sup.3 per hour is divided by 2 kg cobalt nitrate to provide a GHSV is 10 Nm.sup.3 per/kg cobalt nitrate/hour.

[0099] Heating rate of the precursor: The heating rate of the loaded catalyst support refers to the rate at which the loaded catalyst support introduced into the calcination apparatus (calciner) is heated to reach the reactor temperature. That is the heating rate is the difference between the reactor temperature (end temperature) and the temperature of the loaded catalyst support as it is introduced into the reactor (start temperature) divided by the time it takes for the loaded catalyst support to reach the end temperature from the start temperature.

[0100] Turbidity: Ultra-fines, defined as <5 μm particles, are not always accurately measured by the PSD method (Saturn digisizer) or by sieving. Turbidity measurements are used instead to measure catalyst ultra-fines with ultrasonic treatment. Ultrasonic exposure of the catalyst dislodges fine particulates from the main particle which scatter or absorb light, giving the medium under investigation a cloudy appearance. A turbidity meter measures the intensity of scattered light. The higher the intensity of scattered light, the higher the turbidity reading that will be observed.

[0101] Turbidity was measured by filling four 100 ml beakers with 2.00 g of catalyst sample and 38 ml of deflocculated water, with a turbidity of <0.5 Nephelometric Turbidity Unit (NTU) and placing it in an ultrasonic bath filled with 700 ml water @ 25° C. The samples were exposed to ultrasound for four minutes @ 40 kHz frequency and 70 W ultrasonic power and measuring the turbidity in NTU.

[0102] Calcination at a high heating rate: Calcination at a heating rate higher than 10° C./min.

EXAMPLES

Example 1 (Comparative): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .(C5121, pH=2.3) at a Low Heating Rate of 1° C./Min

[0103] Modified silica support: Titanium (IV) iso-propoxide (17.2 g) was added to dry ethanol (130 g) and allowed to mix for 10 minutes. 100 g Amorphous, pre-shaped CARiACT Q-30 silica-gel (average pore diameter of 30 nm), as obtained from Fuji Silysia Chemical Ltd., was added to the resulting solution and allowed to mix for a further 10 minutes. The ethanol was removed under reduced pressure using the drying profile in Table 1 to obtain a free flowing powder. The thus obtained Ti—SiO.sub.2 modified catalyst support material was calcined in a muffle oven at 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 SiO.sub.2.

TABLE-US-00001 TABLE 1 Drying profile for the Ti impregnated modified catalyst support material Pressure Temperature Time (mbar) (° C.) (min) 842 60 10 500 60 30 400 60 30 300 60 30 200 60 60 100 60 60 50 60 60

[0104] Catalyst precursor: In a first metal impregnation step, Co(NO.sub.3).sub.2.6H.sub.2O (7.56 kg), Mn(NO.sub.3).sub.2.4H.sub.2O (1.44 kg) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (5.06 g) were dissolved in water (12.24 kg). The pH of the solution was adjusted to 2.3 after the addition of the Co(NO.sub.3).sub.2.6H.sub.2O using diluted nitric acid. 10.2 kg Ti—SiO.sub.2 modified catalyst support material as described above was added to the solution and stirred for 10 minutes. The excess water was removed under reduced pressure in a conical dryer until the desired 33.3% of the Co(NO.sub.3).sub.2.6H.sub.2O crystal waters were removed by using the drying profile in Table 2.

[0105] The percentage of crystal waters removed is calculated from the mass change measured during loss on ignition (LOI) at 400° C.

TABLE-US-00002 TABLE 2 Drying profile of the impregnated (loaded) catalyst support material Pressure Temperature Time [mbar] [° C.] [min] atm 60 10 220 60 15 220 75 30 220 85 30 220-120 85 120 120-50  100 180

[0106] The dried impregnated free flowing support material powder thus obtained was calcined in a fluidized bed calciner at a heating rate of 1° C./min to 250° C. with a hold time of 6 hours using a GHSV of 2.5 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour. The resulting catalyst precursor comprised of 15 g Co/0.0255 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2.

[0107] In a second metal impregnation step, Co(NO.sub.3).sub.2.6H.sub.2O (6.62 kg) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (8.87 g) were dissolved in water (13.47 kg). The pH of the solution was adjusted to 2.3 using diluted nitric acid. The calcined material of the first impregnation step (11.2 kg) was added to the solution and stirred for 10 minutes. The excess water was removed under reduced pressure in a conical dryer until the desired 33.3% of the Co(NO.sub.3).sub.2.6H.sub.2O crystal waters were removed by using the drying profile in Table 2. Similar fluidisation calcination conditions followed as applied to after the first impregnation step. The resulting catalyst precursor included 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2.

[0108] The particle size distribution of the catalyst precursor was analysed by means of a commercially available Saturn DigiSizer™ 5200 and the percentage of fine material smaller than 45 micron was reported to establish catalyst break-up.

Example 2 (Comparative): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .at a Low Heating Rate of 5° C./Min (C5459, pH=2.3)

[0109] A catalyst precursor was prepared as described in Example 1, but without the second metal impregnation step, and the dried impregnated free flowing support material powder obtained after the 1.sup.st impregnation step was calcined in a fluidized bed calciner at a heating rate of 5° C./min as opposed to 1° C./min as described in Example 1. The resulting catalyst precursor comprised of 15 g Co/0.025 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2

Example 3 (Comparative): Fluidised Bed Calcination of 15 g Co/0.0255 gPt/2.5 g MAc/100 g Ti/Mn-Modified-SiO.SUB.2 .(2.6 g Ti/3.1 g Mn/100 g SiO.SUB.2.) at a High GHSV of 8.2 Nm.SUP.3.Air/Kg (Co(NO.SUB.3.).SUB.2..6H.SUB.2.O)/Hour (C2170, pH=2.3)

[0110] Modified support: Titanium (IV) iso-propoxide (2.57 kg) was added to dry ethanol (15.9 kg) and allowed to mix for 10 minutes. Amorphous, preshaped silica-gel (15 kg), CARiACT Q-30, 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 3 to obtain a free flowing powder.

TABLE-US-00003 TABLE 3 Drying profile for the modified catalyst support material Pressure Temperature Time (mbar) (° C.) (min) 842 60 10 500 60 30 400 60 30 300 60 30 200 65 60 100 75 60

[0111] Manganese(II)acetate tetrahydrate (2.07 kg) was dissolved in water (22.5 kg) and allowed to mix for 10 minutes. The free flowing powder obtained from the titanium (IV) iso-propoxide modified silica (17.6 kg) was added to this solution and allowed to mix for a further 10 minutes. The water was removed under reduced pressure using the drying profile in Table 3 to obtain a free flowing powder. The support material was calcined 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 TiMn—SiO.sub.2 modified catalyst support included 3.1 g Mn/2.6 g Ti/100 g SiO.sub.2.

[0112] Catalyst precursor: In a first impregnation step, 7.9 kg Co(NO.sub.3).sub.2.6H.sub.2O was dissolved in water (10.31 kg) and the pH of the solution was adjusted to 2.3 using diluted nitric acid. Maleic acid (MAc) (250 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (5.06 g) were thereafter added to the solution. The MnTi—SiO.sub.2 (10 kg) modified catalyst support was added to the mixture and the excess water removed under reduced pressure using the drying profile in Table 4 to obtain a free flowing powder.

TABLE-US-00004 TABLE 4 Drying profile for impregnated catalyst support material Pressure Temperature Time (mbar) (° C.) (min) Atm 60 10 220 60 15 220 75 30 220 85 30 220-120 85 120 120-50  95 180

[0113] The free flowing powder was calcined in a fluidized bed calciner at a heating rate of 0.5° C./min to 250° C. with a hold time of 6 hours using a GHSV of 8.2 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour. The resulting catalyst precursor comprised of 15 g Co/0.0255 g Pt/2.5 g MAc/100 g Ti/Mn-modified-SiO.sub.2 (2.6 g Ti/3.1 g Mn/100 g SiO.sub.2) after the first impregnation.

Example 4 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 67° C./Min at 210° C. (C2173≡C5134, pH=2.3)

[0114] Dried metal impregnated catalyst support material was prepared as described in Example 1; however, the loaded support material was fed semi-continuously at a high heating rate into a fluidised bed calciner as opposed to fluidisation calcination as described in Example 1.

[0115] The high heating rate calcination was performed by feeding small, multiple batches of impregnated catalyst support material via a flush spool piece to a pre-heated 6 inch fluidized bed reactor or continuously via a rotary valve during commercial production to control a constant NO.sub.2 release. The calciner was pre-heated under air flow to a reactor temperature of 210° C. 75-100 g impregnated catalyst support material was loaded by flashing the material using a flush spool piece with nitrogen into the reactor. The procedure was repeated every 4-10 minutes in a period of 10-12 hours for ˜10 kg batches. With a loading size of 75 g and air flow of 10 kg/h, the maximum concentration of NO.sub.2 in the off-gas was calculated to be ±15000 ppm. Once all the material was loaded into the fluidised bed calciner, the reactor temperature was increased to 250° C. for final hold and held for a period until all remaining NO.sub.2 was released. The high heating rate calcination conditions and final hold are summarised in Table 5. The resulting catalyst precursor comprised of 15 g Co/0.0255 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2.

TABLE-US-00005 TABLE 5 High heating rate fluidised bed calcination conditions High heating rate calcination Average solids feed rate kg/h 1.26 Air flow kg/h 9.2 Linear gas velocity cm/s 13.7 GHSV Nm.sup.3air/kg.sub.Co(NO3)2•6H2O 14.76 Reactor temperature ° C. 210 Heating rate of precursor ° C./min 67 NO.sub.2 concentration ppm (average) 6 000-9 000 NO.sub.2 concentration mol/kg catalyst 2.21 Feed time h 10-12 Final hold Reactor temperature ° C. 250 Heating rate ° C./min 0.5 Hold time h 6

[0116] A second active metal impregnation step followed as described in Example 1 and calcined at a high heating rate as described above in Table 5 to form a catalyst with a composition of 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2.

Example 5: Catalyst Activation

[0117] The calcined catalyst precursors as described above in Example 1 and Example 4 were reduced prior to Fischer-Tropsch synthesis (FTS) over a H.sub.2 flow with a GHSV of 2.0 Nm.sup.3/hr/kg calcined catalyst and a heating rate of 1° C./min to 390° C. and hold for 7 hours. The reduced catalyst was cooled down, embedded in molten wax and loaded in a continuous stir tank reactor (CSTR) under an inert gas blanket.

Example 6: Fischer-Tropsch Synthesis (FTS)

[0118] The FTS performance of the activated, wax protected catalysts as described in Example 5 were evaluated on a laboratory micro slurry CSTR at a reactor temperature of 230° C. and a reactor pressure of about 15 bar over a total feed molar H.sub.2/CO ratio of about 1.5/1. The 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 75-78%. The water partial pressure was about 5.5 bar.

Discussion

[0119] Poor fluidisation stability, that is, either dP instability or NO.sub.2 profile scatter or temperature scatter over the bed, was observed for the fluidised calcined catalyst precursors as described in Example 1 (see FIG. 1) whereas the high heating rate fluidised calcined catalyst precursor as described in Example 4 demonstrated good fluidisation stability at a reactor bed temperature of 210° C. (see FIG. 2) with no dP instability and temperature scatter. A 1 hour period enlargement of the calcination profile of FIG. 2 is shown in FIG. 3 and demonstrates controlled, multiple single NO.sub.2 peaks during calcination at high heating rates.

[0120] The Co.sub.3O.sub.4 crystallite size of the high heating rate calcined catalyst precursor (Example 4) was smaller than the fluidisation bed calcination catalyst precursor of Example 1 and Example 2 (see Table 6) and resulted in a FTS catalyst with higher activity compared to the low heating rate fluidised bed calcination as described in Example 1 (see FIG. 4). Increasing the heating rate during fluidised bed calcination to 5° C./min in Example 2 did not solve the poor fluidisation as is evident from the large Co.sub.3O.sub.4 crystallite sizes observed which may be due to migration of the cobalt (see Table 6).

[0121] Even though no bed dP instability was observed at the high GHSV of 8 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour of Example 3, a NO.sub.2 profile scatter was still observed which typically yields poor catalyst quality.

[0122] Similar to the low percentage of 1.7% fine material smaller than 45 micron in the catalyst precursor of Example 1 that was calcined at a low heating rate, the percentage of fine material smaller than 45 micron in the catalyst precursor of Example 4 was only 1.3% (see Table 6) and is indicative of very low break-up of the catalyst precursor calcined at a high heating rate.

TABLE-US-00006 TABLE 6 Fluidised bed calcination stability and catalyst precursor characteristics when the loaded support was fed semi-continuously at a high heating rate to the calciner versus low heating rate calcination Fluidised bed Heating GHSV, Co.sub.3O.sub.4 Indication of calcination rate, Nm.sup.3/ crystallite poor Fines <45 Catalyst, method ° C./min kg.sub.Co(NO3)2•6H2O size, nm fluidisation μm (%) Example 1 ex Low heating 1 2.5 24 dP instability, 1.sup.st impregnation rate NO.sub.2 profile Example 1 ex 34 scatter 1.7 2.sup.nd impregnation Example 2 ex Low heating 5 2.5 32 1.sup.st impregnation rate Example 3 ex Low heating 0.5 8.2 — NO.sub.2 profile 1.sup.st impregnation rate scatter Example 4 ex High heating 67 14.76 12 none 1.sup.st impregnation rate Example 4 ex 16 1.3 2.sup.nd impregnation

Example 7 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 106° C./Min at 210° C. (C5123≡C2173 Small Scale, pH=2.3)

[0123] A catalyst precursor was prepared as described in Example 4, but on a smaller scale; that is, 50 g support material was used as opposed to 10 kg or 15 kg support material. All other raw materials used during the catalyst precursor preparation were scaled down accordingly. The high heating rate calcination conditions and final hold are summarised in Table 7. A continuous catalyst precursor feed rate of 0.7 g/min was used.

TABLE-US-00007 TABLE 7 Small laboratory scale high heating rate fluidised bed calcination conditions High heating rate calcination Average solids feed rate kg/h     0.042 Air flow kg/h    0.2 Linear gas velocity cm/s    5.97 GHSV Nm.sup.3air/kg.sub.Co(NO3)2•6H2O    9.63 Reactor temperature ° C. 210 Heating rate of precursor ° C./min 106 NO.sub.2 concentration ppm (average) 14 000   NO.sub.2 concentration mol/kg catalyst    2.22 Final hold Reactor temperature ° C. 250 Heating rate ° C./min  1 Hold time h  6

[0124] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Example 8 (Comparative): Fluidised Bed Calcination of 15 g Co/0.0255 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 15° C./Min at 120° C. (C5128, pH=2.3)

[0125] A catalyst precursor was prepared as described in Example 7, but without the second metal impregnation step and the calcination bed temperature applied to the bed was 120° C. as opposed to 210° C. as described in Example 7. The final hold period was similar to Example 7 (Table 7).

Example 9 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 106° C./Min at 210° C. with Final Hold at 340° C. (C5143, pH=2.3)

[0126] A catalyst precursor with the composition 30 g Co/0.075 g Pt/3.1 g Mn/100 g Ti—SiO.sub.2 was prepared as described in Example 7; however, the final hold temperature of the bed was 340° C. as opposed to 250° C.

Discussion

[0127] The impregnated catalyst support that was calcined at a high heating rate of 15° C./min to only 120° C. (Example 8) (and not to at least 165° C.) resulted in a catalyst precursor with large Co.sub.3O.sub.4 crystallite sizes compared to Example 7 and Example 9. Smaller Co.sub.3O.sub.4 crystallite sizes were obtained for the catalyst precursors that were calcined at 210° C.; that is, calcination over the full temperature range A (see Examples 7 and Example 9).

[0128] Similar Co.sub.3O.sub.4 crystallite sizes were obtained with a final hold temperature of 340° C. (Example 9) as compared to a final hold temperature of 250° C. (Example 7).

TABLE-US-00008 TABLE 8 High heating rate fluidised bed calcination results at various reactor temperatures and final hold bed temperatures Heating Reactor rate of GHSV, Nm.sup.3/mol NO.sub.3 Final Co.sub.3O.sub.4 bed precursor, (Nm.sup.3/kg hold Crystallite Turbidity, Catalyst T, ° C. ° C./min Co(NO.sub.3)2•6H.sub.2O) T, ° C. size, nm NTU Example 4 ex 1.sup.st 210 67  1.84 (14.76) 250 12 83 impregnation Example 4 ex 2.sup.nd 210 67  1.84 (14.76) 250 16 62 impregnation Example 7 ex 1.sup.st 210 106 1.20 (9.63) 250 14 — impregnation Example 8 ex 1.sup.st 120 15 1.20 (9.63) 250 48 118  impregnation Example 9 ex 2.sup.nd 210 106 1.20 (9.63) 340 16 — impregnation ex 1.sup.st impregnation = 15 g Co/0.0255 g Pt/3.1 g Mn/100 g support (2.6 g Ti/100 gSiO.sub.2) ex 2.sup.nd impregnation = 30 g Co/0.075 g Pt/3.1 g Mn/100 g support (2.6 g Ti/100 gSiO.sub.2)

Example 10 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 106° C./Min at 210° C. (C5166, pH=2.3)

[0129] A catalyst precursor was prepared as described in Example 7; however, the Mn(NO.sub.3).sub.2.4H.sub.2O loading during the 1.sup.st impregnation step was reduced to give a catalyst precursor composition of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.sub.2. The final hold period was similar to Example 7 (Table 7).

[0130] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Example 11 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 106° C. at 210° C. (C5167≡C2178, pH=5)

[0131] A catalyst precursor with composition 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti-silica support (2.6 g Ti/100 g silica) was prepared as described in Example 10. However, the first impregnation entailed the addition of 1 gram cobalt hydroxide in addition to cobalt nitrate, changing the pH of the solution to 5. The pH of the second impregnation solution was again adjusted to 2.3 with no cobalt hydroxide addition.

[0132] The precursor was prepared as follows: Modified silica support material as described in Example 1 was used as support material. Co(NO.sub.3).sub.2.6H.sub.2O (34.57 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (0.025 g) were added to 60 g of water and stirred for 10 minutes at 85° C. to allow dissolution of the cobalt nitrate and platinum salts. The pH was adjusted to 2.3 using dilute nitric acid. Co(OH).sub.2 (0.79 g) and Mn(NO.sub.3).sub.2.4H.sub.2O (5.02 g) were added to the solution. The pH of the turbid solution exceeded 4.5. No further pH adjustments were made and the solution was stirred for another 10 minutes at 85° C. 50 g Ti-modified support was added to the solution. The excess water was removed under reduced pressure using the drying profile as described in Table 9 to obtain a free flowing powder. The loaded support was fed continuously at a high heating rate into a fluidised bed calciner at conditions as described in Example 7, Table 7. The catalyst precursor comprised of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.sub.2 with 1 g of the Co from Co(OH).sub.2.

[0133] In a second impregnation step, Co(NO.sub.3).sub.2.6H.sub.2O (30.75 g) and (NH.sub.4).sub.3Pt(NO.sub.3).sub.2 (0.049 g) were dissolved in water (60 g) and 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 added to the solution and stirred for 10 minutes. The excess water was removed under reduced pressure using the drying profile as described in Table 9 to obtain a free flowing powder with a LOI.sub.400 of 23.8% (35.2% of the Co(NO.sub.3).sub.2.6H.sub.2O crystal waters were removed).

TABLE-US-00009 TABLE 9 Drying profile of the impregnated catalyst support material Pressure Temperature Time [mbar] [° C.] [min] 250 85 30 250-130 85 120 130-50  85 15  50 85 180

[0134] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Example 12 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/1.6 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 106° C./Min at 210° C. (C5190, pH=5)

[0135] A catalyst precursor was prepared as described in Example 11; however, the Mn(NO.sub.3).sub.2.4H.sub.2O loading during the 1.sup.st impregnation step was reduced to give a catalyst precursor composition of 30 g Co/0.075 g Pt/1.6 g Mn/100 g Ti—SiO.sub.2. The final hold period was similar to Example 7 (Table 7).

[0136] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Example 13 (Comparative): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .(C5301, pH=5) at a Low Heating Rate of 1° C./Min

[0137] A catalyst precursor was prepared as described in Example 11; however, the impregnated support was calcined as described in Example 1; that is, fluidised bed calcination at a heating rate of 1° C./min to 250° C. with a hold time of 6 hours using a GHSV of 2.5 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour.

[0138] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Discussion

[0139] From Table 10 the active metal surface area (MSA) of Example 12 (1.6 g Mn loading/100 g Ti—SiO.sub.2) is the highest compared to Example 10 and Example 11 and the reduction temperature thereof the lowest compared to Example 7, Example 10 and Example 11. The FTS activity of Example 10 with a 2.2 g Mn/100 g support is higher compared to the 3.1 g Mn/100 g support of Example 7 (see FIG. 4). The higher pH obtained with the addition of Co(OH).sub.2 during the 1.sup.st impregnation step (Example 11 and Example 12), then again, resulted in an even higher FTS activity compared to the lower pH impregnation solution of Example 10 (see FIG. 4).

TABLE-US-00010 TABLE 10 Characteristics of the catalyst precursors calcined at high heating rates (the reactor temperature was 210° C. and final hold 250° C.) Ex 2.sup.nd impregnation Active metal Mn 1.sup.st Co.sub.3O.sub.4 surface area Reduction level/100 g impregnation crystallite (m.sup.2/g) @ 390° C. T of CoO Catalyst support pH pH agent size, nm reduction to Co, ° C. Example 7 3.1 2.3 HNO.sub.3 16 268 Example 10 2.2 2.3 HNO.sub.3 16 5.9 250 Example 11 2.2 5 Co(OH).sub.2 15 5.2 262 Example 12 1.6 5 Co(OH).sub.2 16 6.6 236

[0140] Similar to comparing low heating rate fluidised bed calcination of Example 1 with high heating rate calcination of Example 4, the Co.sub.3O.sub.4 crystallite size of the fluidised bed calcination catalyst precursor of Example 13 was larger than the high heating rate fluidised calcined catalyst precursor of Example 11 (see Table 11) and resulted in a FTS catalyst with lower activity (see FIG. 4) compared to high heating rate calcination.

[0141] Even though a lower Mn level and increased pH during the 1.sup.st impregnation step improved the FTS performance of Example 13 compared to Example 1, fluidisation instability was still observed during low heating rate fluidised bed calcination.

TABLE-US-00011 TABLE 11 Comparison in catalyst precursor characteristics when calcined at a high heating rate versus a low heating rate. Fluidised % Difference in Mn 1.sup.st bed Co.sub.3O.sub.4 Indication FT rate from level/100 g impregnation calcination crystallite of poor Ex. 4 after 10 Catalyst, support pH method size, nm fluidisation days Example 1 3.1 2.3 Low 34 dP −33.5 heating instability rate Example 4 3.1 2.3 High 16 none 0 heating rate Example 11 2.2 5 High 15 none 68.1 heating rate Example 13 2.2 5 Low 21 dP −5.0 heating instability rate

Example 14 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 138° C./Min at 250° C., No Final Hold Time, but 20 Minutes Residence Time as a Result of Loading Inventory (C5315, pH=5)

[0142] A catalyst precursor was prepared as described in Example 11; however, the calcination bed temperature applied to the bed was 250° C. The catalyst precursor was removed from the calciner immediately after the whole inventory was loaded.

Discussion

[0143] The small NO.sub.2 peak in the NO.sub.2 profile once the bed is heated from 210° C. to 250° C. in FIG. 2 indicates that the high heating rate fluidisation calcination does not remove all the traces of NO.sub.2. From CHNS elemental analysis and the Co.sub.3O.sub.4 phase abundance XRD data, a final hold period of >20 minutes is required to get rid of all these residual nitrogen compounds (see Table 12).

TABLE-US-00012 TABLE 12 Minimum final hold time N- Co.sub.3O.sub.4 content, Reactor Final Final Crystallite Relative phase abundance, % % from bed hold hold size, Anatase CHNS Catalyst T, ° C. T, ° C. time, min nm Co.sub.3O.sub.4 Co.sub.2SiO.sub.4 Co(NO.sub.3).sub.2•(H.sub.2O).sub.2 Mn(NO.sub.3).sub.2•(H.sub.2O).sub.2 TiO.sub.2 analysis Ex. 11 210 250 360 15 70 22 8 0.21 Ex. 14 250 250 20 15 29 32 18 21 2.87

Example 15 (Inventive): Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate 68° C./Min at 210° C. (C2179, pH=5)

[0144] A catalyst precursor was prepared as described in Example 11; but on a larger scale; that is, 15 kg Ti-modified catalyst support material as described in Example 1 was used as opposed to 50 g support material. All other raw materials used during the catalyst precursor preparation were scaled accordingly. The excess water was removed under reduced pressure in a conical dryer using the drying profile as described in Table 2 to obtain a free flowing powder. 44% of the Co(NO.sub.3).sub.2.6H.sub.2O crystal waters was removed. The dried impregnated support material was unloaded and divided into small batches for pilot plant calcination at 210° C. as described in Example 4, Table 5. The final hold period was similar to Example 4 (Table 5).

Example 16 (Inventive): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 48° C./Min at 180° C. (C2179, pH=5)

[0145] A catalyst precursor was prepared as described in Example 15, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 180° C. as opposed to 210° C. as described in Example 15.

Example 17 (Inventive): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 144° C./Min at 250° C. (C2179, pH=5)

[0146] A catalyst precursor was prepared as described in Example 15, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 250° C. as opposed to 210° C. as described in Example 15.

Example 18 (Comparative): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 30° C./Min at 130° C. (C5517 Small Scale, Run DI092, pH=5)

[0147] A catalyst precursor was prepared as described in Example 11, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 130° C. prior to the final hold period as opposed to 210° C. as described in Example 11. The final hold period was similar to Example 7 (Table 7).

Example 19 (Comparative): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 38° C./Min at 140° C. (C5446 Small Scale, Run DG093, pH=5)

[0148] A catalyst precursor was prepared as described in Example 11, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 140° C. prior to the final hold period as opposed to 210° C. as described in Example 11. The final hold period was similar to Example 7 (Table 7).

Example 20 (Comparative): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 48° C./Min at 150° C. (C5491 Small Scale, Run DD079, pH=5)

[0149] A catalyst precursor was prepared as described in Example 11, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 150° C. prior to the final hold period as opposed to 210° C. as described in Example 11. The final hold period was similar to Example 7 (Table 7).

Example 21 (Comparative): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 53° C./Min at 160° C. (C5506 Small Scale, Run DI091, pH=5)

[0150] A catalyst precursor was prepared as described in Example 11, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 160° C. prior to the final hold period as opposed to 210° C. as described in Example 11. The final hold period was similar to Example 7 (Table 7).

Example 22 (Inventive): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 66° C./Min at 170° C. (C5503 Small Scale, Run DC088, pH=5)

[0151] A catalyst precursor was prepared as described in Example 11, but without the second metal impregnation step, and the calcination reactor temperature applied to the bed after the 1.sup.st impregnation step was 170° C. prior to the final hold period as opposed to 210° C. as described in Example 11. The final hold period was similar to Example 7 (Table 7).

Example 23 A: Catalyst Activation and Fischer-Tropsch Synthesis (FTS)

[0152] Samples of the calcined catalyst precursors of Example 16-Example 22 were reduced after the first impregnation step over a H.sub.2 flow with a GHSV of 2.0 Nm.sup.3/hr/kg calcined catalyst and at a heating rate of 1° C./min to 370° C. and hold for 7 hours. The reduced catalyst was cooled down, embedded in molten wax and loaded in a continuous stir tank reactor (CSTR) under an inert gas blanket to evaluate the Fischer-Tropsch synthesis performance thereof.

[0153] The FTS performance of the activated, wax protected catalysts as described above was evaluated on a laboratory micro slurry CSTR at a reactor temperature of 230° C. and a reactor pressure of about 20 bar over a total feed molar Hz/CO ratio of about 2/1. The 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 80%. The water partial pressure was about 8 bar.

Discussion

[0154] Turbidity results indicate that less ultra-fines form by increasing the calcination reactor temperature with lowest turbidity readings for calcination reactor temperatures of 210° C. (Example 15) and 250° C. (Example 17) of FIG. 5.

[0155] The impregnated catalyst support of Example 18 that was calcined at a high heating rate up to 130° C. resulted in catalyst precursors with very large Co.sub.3O.sub.4 crystallite sizes (see Table 13) as compared to the higher temperature calcination example of Example 22. The FTS activity was also significantly lower for the catalyst of Example 18 (see FIG. 6). The FTS activities were the best for catalysts that were calcined at high heating rates to temperatures higher than 160° C. (see FIG. 6).

TABLE-US-00013 TABLE 13 High heating rate fluidised bed calcination catalyst precursor characteristics at various reactor temperatures (final hold temperature for all was 250° C.) Heating Reactor rate for GHSV, Nm.sup.3/mol Co.sub.3O.sub.4 bed T, precursor, NO.sub.3 (Nm.sup.3/kg Crystallite Catalyst ° C. ° C./min Co(NO.sub.3).sub.2•6H.sub.2O) size, nm Turbidity, NTU* Example 15 ex 1.sup.st 210 67 1.84 (14.76) 10 69 impregnation, #292 Example 15 ex 2.sup.nd 210 68 1.84 (14.76) 13 34 impregnation, #293 Example 16 ex 1st 180 48 1.84 (14.76) 11 124 impregnation, #295 Example 17 ex 1.sup.st 250 144 1.84 (14.76) 12 77 impregnation, #294 Example 18 ex 1.sup.st 130 30 1.2 (9.63) 48 266 impregnation Example 19 ex 1.sup.st 140 38 1.2 (9.63) 17 210 impregnation Example 20 ex 1.sup.st 150 48 1.2 (9.63) 16 — impregnation Example 21 ex 1.sup.st 160 53 1.2 (9.63) 11 115 impregnation Example 22 ex 1.sup.st 170 66 1.2 (9.63) 10 — impregnation *Ultrasonic- turbidity error ± 19 NTU

Example 23 (Inventive): Low Heating Rate Fluidisation Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .(C5372, pH=5) Up to 80° C. at 1° C./Min Followed by High Heating Rate Calcination of 138° C./Min at 250° C.

[0156] Dried impregnated free flowing support powder prepared as described in Example 11 was calcined at a low heating rate of 1° C./min up to 80° C. using a GHSV of 2.5 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour and calcined thereafter at a high heating rate at 250° C. using a GHSV as shown in Table 7.

Example 24 (Inventive): Low Heating Rate Fluidisation Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .(C5377, pH=5) Up to 90° C. at 1° C./Min Followed by a High Heating Rate of 138° C./Min Calcination at 250° C.

[0157] Dried impregnated free flowing support powder prepared as described in Example 11 was calcined at a low heating rate of 1° C./min up to 90° C. using a GHSV of 2.5 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour and calcined thereafter at a high heating rate at 250° C. using a GHSV as shown in Table 7.

Example 25 (Inventive): Low Heating Rate Fluidisation Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .(C5378, pH=5) Up to 100° C. at 1° C./Min Followed by a High Heating Rate of 138° C./Min Calcination at 250° C.

[0158] Dried impregnated free flowing support powder prepared as described in Example 11 was calcined at a low heating rate of 1° C./min up to 100° C. using a GHSV of 2.5 Nm.sup.3air/kg (Co(NO.sub.3).sub.2.6H.sub.2O)/hour and calcined thereafter at a high heating rate @ 250° C.

Example 26 (Inventive): Fluidised Bed Calcination of 15 g Co/0.025 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 138° C./Min at 250° C. (C5390, pH=5)

[0159] A catalyst precursor was prepared as described in Example 17, but on a smaller scale; that is, 50 g support material was used as opposed to 10 kg support material. All other raw materials used during the catalyst precursor preparation were scaled down accordingly.

Discussion

[0160] Some negative effects started to arise by calcining the impregnated catalyst support at low heating rates at temperatures as low as 90° C. (Example 24). This included poorer Co distribution which may be due to Co migration to the periphery of the particle (see Table 14). The catalyst precursor of Example 25 which was calcined at a low heating rate of 1° C./min up to 100° C. in a fluidised bed further formed more ultra-fines during ultrasonic exposure with higher turbidity readings compared to Example 26 (see Table 14).

[0161] Quantitative Energy Dispersive Spectroscopy (EDS) was done and the normalized mass % at different regions of the particle was determined to represent and compare the distribution and migration of the cobalt of Example 23-Example 26 in numerical form. The Co/Si mass % ratio was then determined at the particle edge (first 5 microns of the particle) and the middle of the particle.

[0162] Since the edge of the particle in Example 24 and Example 25 had a higher Co/Si mass % normalized ratio than the middle of the particle, it shows quantitatively that an uneven distribution is present compared to Example 23 and Example 26. An even cobalt distribution was obtained in Example 23 and Example 26 where the Co/Si mass % normalized ratio are similar at the particle edge and in the middle of the particle (see Table 14).

TABLE-US-00014 TABLE 14 Low heating rate fluidisation calcination between 80-100° C. followed by high heating rate calcination at 250° C. Low High Co/Si normalized mass % ratio heating heating Co.sub.3O.sub.4 (Mean ± 95% confidence interval) rate bed rate bed Crystallite Turbidity, Particle edge Middle of Catalyst T, ° C. T, ° C. size, nm NTU (first 5 microns) particle Example 23 80 250 12 72 0.4 ± 0.0 0.4 ± 0.1 Example 24 90 250 12 79 0.6 ± 0.0 0.2 ± 0.0 Example 25 100 250 13 141 0.6 ± 0.1 0.1 ± 0.0 Example 26 — 250 12 77 0.4 ± 0.0 0.3 ± 0.0

Example 27: Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 68° C./Min at 210° C. (C2177, pH=5) where Only 16% Co(NO.SUB.3.).SUB.2..6H.SUB.2.O Crystal Waters were Removed

[0163] A catalyst precursor was prepared as described in Example 15; however, the excess water was removed under reduced pressure in a Lödige dryer as opposed to a conical dryer using the drying profile in Table 15 to obtain a free flowing powder. Only 16% Co(NO.sub.3).sub.2.6H.sub.2O crystal waters were removed with a final LOI.sub.400 of 25.9%.

[0164] The catalyst precursor was activated as described in Example 5 and thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

TABLE-US-00015 TABLE 15 Drying profile of the impregnated support in a Lödige dryer Pressure Temperature Time [mbar] [° C.] [min] Atm 60 10 220 60 15 220 75 30 220 85 30 220-120 85 120 120-50  100 240

Discussion

[0165] The Co.sub.3O.sub.4 crystallite size of the catalyst precursor as prepared in Example 27 with a final LOI of 25.9% was larger than the crystallites size obtained in Example 15 with a final LOI of 22.8%. The FT synthesis activity was consequently also lower compared to Example 15 (see Table 16).

TABLE-US-00016 TABLE 16 Effect of drying on crystallite size and FT synthesis activity % % Difference in activity Co(NO.sub.3).sub.2•6H.sub.2O Co.sub.3O.sub.4 crystallite size, nm of Example 27 (CB245) Crystal water Final ex 1.sup.st ex 2.sup.nd relative to Example 15 Catalyst removed LOI.sup.400, % impregnation impregnation (CB246) after 10 days Example 27 16% 25.9 16 18 −24 Example 15 44% 22.8 10 13 0

Example 28 (Comparative): Fixed Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .(C5253)

[0166] A catalyst precursor was prepared as described in Example 11; however the impregnated catalyst support was calcined in a fixed bed at a heating rate of 0.5° C./min in a 12% O.sub.2+He flow (0.5 ml/s) up to 150° C., 175° C. and 250° C.

[0167] The decomposition products of Co(NO.sub.3).sub.2.6H.sub.2O were measured by means of FTIRS with gas phase analysis.

Example 29 (Comparative): Fixed Bed Calcination of 30 g Co/0.075 gPt/2.5 g MAc/100 g Ti/Mn-Modified-SiO.SUB.2 .(2.6 g Ti/3.1 g Mn/100 g SiO.SUB.2.) (C5252)

[0168] A catalyst precursor was prepared as described in Example 3; however the impregnated catalyst support was calcined in a fixed bed at a heating rate of 0.5° C./min in a 12% 02+He flow (0.5 ml/s) up to 130° C., 175° C. and 250° C.

[0169] The decomposition products of Co(NO.sub.3).sub.2.6H.sub.2O were measured by means of FTIRS with gas phase analysis.

Discussion

[0170] The TPO profiles of H.sub.2O, NO.sub.2 and HNO.sub.3 (g) during linear heating at 0.5° C./min of Example 28 and Example 29 are shown in FIG. 7 and FIG. 8. From FIG. 7, it is seen that water is released at 70° C. and 105° C. while both the NO.sub.2 and HNO.sub.3(g) are released at 140° C. and 175° C. The evolution point of the NO.sub.2 at quantities of NO.sub.2 of 1500 ppm(v) (0.15-vol-%) is at 115° C. (see FIG. 7). In contrast to Example 28, the addition of an organic modifier in Example 29 resulted in a shift in the said evolution point of the NO.sub.2 at 125° C. with the NO.sub.2 peak at 155° C.

Example 30: Fluidised Bed Calcination of 30 g Co/0.075 g Pt/2.2 g Mn/100 g Ti—SiO.SUB.2 .at a High Heating Rate of 233° C./Min at 350° C. (C5389)

[0171] A catalyst precursor was prepared as described in Example 11; however, the calcination reactor temperature applied to the bed after the 1.sup.st and 2.sup.nd impregnation steps was 350° C.

[0172] The catalyst precursor was activated as described in Example 5 and the resulting catalyst thereafter tested for its slurry phase FTS performance on a micro slurry CSTR under conditions as described in Example 6.

Discussion

[0173] The catalyst that was calcined at a high heating rate at 350° C. resulted in a poorer FTS performance (see FIG. 4). The relative phase abundance % of the inactive Co.sub.2SiO.sub.4 was also higher (see Table 17).

TABLE-US-00017 TABLE 17 Catalyst precursor characteristics calcined at a high heating rate at 350° C. Heating Reactor Final rate for Co.sub.3O.sub.4 Relative phase bed hold precursor, Crystallite abundance, % Catalyst T, ° C. T, ° C. ° C./min size, nm Co.sub.3O.sub.4 Co.sub.2SiO.sub.4 Ex. 11 210 250 67 15 70 22 Ex. 30 350 250 233 8 73 27