ZA200810397B - Improvement in the efficiency of catalysts - Google Patents
Improvement in the efficiency of catalysts Download PDFInfo
- Publication number
- ZA200810397B ZA200810397B ZA200810397A ZA200810397A ZA200810397B ZA 200810397 B ZA200810397 B ZA 200810397B ZA 200810397 A ZA200810397 A ZA 200810397A ZA 200810397 A ZA200810397 A ZA 200810397A ZA 200810397 B ZA200810397 B ZA 200810397B
- Authority
- ZA
- South Africa
- Prior art keywords
- catalyst
- microwave
- microwave absorbing
- improving efficiency
- efficiency
- Prior art date
Links
- 239000003054 catalyst Substances 0.000 title claims description 109
- 230000006872 improvement Effects 0.000 title description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 85
- 229910052742 iron Inorganic materials 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 33
- 230000008569 process Effects 0.000 claims description 31
- 150000001336 alkenes Chemical class 0.000 claims description 20
- 230000005855 radiation Effects 0.000 claims description 16
- 229930195733 hydrocarbon Natural products 0.000 claims description 14
- 150000002430 hydrocarbons Chemical class 0.000 claims description 14
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims description 11
- 239000004711 α-olefin Substances 0.000 claims description 11
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 6
- 229910052700 potassium Inorganic materials 0.000 claims description 6
- 239000011591 potassium Substances 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 4
- 150000001340 alkali metals Chemical class 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical group [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 10
- 239000000377 silicon dioxide Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000006555 catalytic reaction Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 101100463469 Caenorhabditis elegans lin-42 gene Proteins 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000012018 catalyst precursor Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical class [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000011949 solid catalyst Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
-2- - 2 0 . «DE J
IMPROVEMENT OF FISCHER-TROPSCH CATALYSTS
This invention relates to a process for improving performance of a microwave absorbing catalyst, more particularly but not exclusively an iron-based microwave absorbing catalyst used in Fischer-Tropsch catalysis.
Fischer-Tropsch catalysis provides a proven method for the conversion of a synthesis gas into hydrocarbons, particularly liquid hydrocarbons. The preferred : industrial catalysts are based on iron or cobalt or combinations of the two.
Promoters and other additives are usually also present in the catalyst to endow the catalyst with the desired properties, such as activity, selectivity, resistance to deactivation and the like.
EE —
Alkali metals, especially potassium, are often used, particularly with iron-based catalysts, as promoters. : Considerable attention has been given to the quality of the hydrocarbon products produced by Fischer-Tropsch reactions, especially with regard to their olefin content, and especially their alpha-olefin content, since these factors determine the value of the products and the ease with which they can be exploited for petrochemical feedstock use.
Ongoing research is also being conducted around the world to improve the efficiency of catalysts used in the Fischer-Tropsch process, and to minimise carbon emissions into the atmosphere. : SUMMARY OF THE INVENTION
In accordance with this invention there is provided a process for improving efficiency of a microwave absorbing catalyst comprising delivering, to said catalyst, a predetermined dose of microwave radiation, the dose being determined to impart optimum efficiency to the catalyst.
There is also provided for the microwave radiation to be delivered to the catalyst by placing the catalyst in a microwave radiation field.
There is further provided for the dose of microwave radiation delivered to the catalyst to be a function of the time the catalyst is placed in the field and/or to the field power of the microwave radiation field.
There is also provided for the catalyst to be a cobalt based catalyst, alternatively an iron based catalyst, preferably a calcined Fe/SiO,.
There is further provided for the Fe/SiO, to be calcined by subjecting it to an elevated temperature, preferably 650°C for about 3 hours.
There is also provided for the iron-based catalyst is pretreated with an alkali metal, preferably potassium.
There is further provided for the catalyst to be used in a Fischer-Tropsch process and for the efficiency of the catalyst to be measured as a function of the olefin content, preferably the level of alpha olefin, in hydrocarbons produced by the : Fischer-Tropsch process.
The invention extends to a microwave absorbing catalyst, preferably a calcined iron based catalyst which has been enhanced in accordance with the above- described process.
There is further provided for the calcined iron based catalyst to be Fe/SiO; and for it to be used in a Fischer-Tropsch process where its efficiency is measured as a function of the olefin content, preferably the level of alpha olefin, in hydrocarbons produced by the Fischer-Tropsch process.
-
Embodiments of the invention will be described below by way reference to the non-limiting examples and to the following figures:
Figure 1. Transmission electron microscope images of unsupported iron catalysts before and after microwave treatment;
Figure 2. Graphical representation of the surface area (m?g™') determination for unsupported iron catalysts before and after microwave : treatment;
Figure 3. Graphical representation of the effect of microwave treatment on olefins in linear hydrocarbons (for a promoted Fe/SiO,);
Figure 4. Graphical representation showing the effect of microwave treatment on CO% conversion before and after microwave treatment (for a promoted Fe/SiO; catalyst):
Figure 5. The effect of microwave power level on olefins in linear hydrocarbons for promoted Fe/SiO. catalysts; and
Figure 6. The Effect of power level on CO % conversion for promoted iron catalysts.
The following non-limiting examples provide some of the results obtained in treating microwave absorbing iron-based catalysts intended for use in Fisher-
Tropsch processes. : EXAMPLE 1 1.1 Experimental Methods
Catalysts were prepared by an incipient wetness impregnation method using silica and ferric nitrate salt. A catalyst precursor was dried for 16h at 120°C, then calcined at 250°C for 6.5h in air. Potassium, when present, was added at the level of 2 mass%. The iron content was 10 mass%.
The catalysts were microwave treated in a commercial microwave oven at nominal power levels expressed as a % of maximum, and for various durations, indicated in seconds.
Fischer-Tropsch catalysis was carried out in a fixed-bed microreactor using 1.0g catalyst. The catalyst was reduced in the reactor at 250°C for 16h in a flow of pure hydrogen. The reaction was then carried out at a total pressure of 22bar using syngas (H2:CO = 2:1 by volume) flowing at 66 Nml/min, at a reaction temperature of 250°C. Products were analyzed using a gas chromatographic arrangement fitted with dual FID/TCD detectors.
: : 1.2. Microwave effect on the particle size of the unsupported iron catalysts
Transmission electron microscope images of the unsupported iron catalysts before and after microwave treatment are shown in Figure 1.
The unsupported iron oxide was calcined at 350°C for 6.5 h and, from
Figure 1, it is evident that when the unsupported iron catalyst was microwave treated at power = 100% for 8 seconds, the particle size of the iron increased. 1.3. Microwave effect on the surface area of the unsupported iron catalyst : The results showing the effects of treating an unsupported iron catalyst on the surface area of the catalyst are represented in table 1 and also graphically in Figure 3. These results demonstrate that microwave heating does not markedly affect the surface area of the unsupported iron catalysts although there is a slight increase.
Catalyst name Surface Area m’g™ rr
Table 1: The effects of treating an unsupported iron catalyst on the surface area of the catalyst. 1.4. Microwave effect on crystallinity of the unsupported iron catalysts
The results presented in table 2 indicate that the crystallinity and the crystalline size of the catalyst increase with the microwave heating.
Catalyst | Crystallinity [Crystalline size name
Table 2: The effects on microwave heating on crystallinity and crystalline size of the catalyst. 1.5. Effect of microwaves on a promoted Fe/SiO, calcined at 350°C for 6.5h k =2%
It is evident from an examination of the results shown in Figures 3 and 4 and from Table 3 that the microwave treatment of a promoted Fe/SiO; catalyst enhances the olefin content and the conversion (CO%) does not change with microwave heating. The addition of a promoter to the
Fe/SiO, catalyst results in decrease in activity which may be due to the fact that potassium covers iron particles, and this limits the availability of iron for the reaction.
oo ' -8- eww paws
Olefins in linear hydrocarbons
Alpha Olefins in linear Olefins
Table 3: Olefin content of microwaved and non-microwaved iron catalysts. 1.6. Effect of power level
Figures 5 and 6 and table 4 present results showing the effect of : microwave power level on the production of olefins in linear hydrocarbons and on conversion of CO. The power level does not affect the catalytic activity (Figure 6) and the carbon number at which the maximum olefin . content is observed is dependent on the power level used when microwaving the catalyst (Figure 5). A lower power level (10% or 20%) is preferable because it provides high olefin content and, at higher power levels, the catalytic performance is reduced.
MWO [{MWS8s p =10% | MWS8s p = 20% | MW8s p = 40%
C5 C7 C5orC4 C5
Olefins in linear 74% 96% 93% 77% hydrocarbons
Alpha Olefins in linear 34% 68% 64% 66%
Olefins
Table 4: Information taken from the carbon number with the highest olefin content.
The above results demonstrated an increase in efficiency, in terms of higher activity, higher olefin content and higher alpha-olefin content, of an iron-based catalyst after treatment in a microwave field.
, .
EXAMPLE 2
In this example a Fe/silica catalyst was prepared as above (Fe 10%/K 2%/silica) but calcined at 3500C for 16h before being loaded into a reactor and then reduced in flowing hydrogen at 3500c for 16h, with FTS reaction : carried out at 2500C with H2:CO = 2:1. 20 bar total pressure.
Catalysts were tested for up to 700 min on stream and steady state data were recorded after, typically, 50-100 min.
Not After microwave microwaved treatment
LLC NC
Degree Fe reduction 70% 73% (TPR)
Fe dispersion (from 4% 15%
H chemisorption)
Table 5: Results of tests conducted on a calcined Fe/Silica catylist before and after microwave radiation 540W exposure for 8s
EXAMPLE 3
In this example an uncalcined catalyst Fe/SiO2 was prepared as above but with no calcinations step. The same tests as were performed on the catalyst if
Example 2 were performed and the results are presented in Table 6.
Not After microwave
I a
Alpha-olefins in lin 42% 45%
Er a
Table 6: Results of tests conducted on an uncalcined Fe/Silica catylist before and after microwave radiation 540W exposure for 8s
RESULTS
The above results demonstrate that that microwave treatment of Fischer-Tropsch catalysts, especially iron-based catalysts, is able under some circumstances to bring about changes in the catalyst selectivity and activity, generally in a favourable manner. This manifests itself in the form of a higher activity, higher -olefin content and higher alpha-olefin content.
It is believed that these changes are the direct result of solid-state modifications induced by microwave treatment, probably occurring as a result of differential temperatures excursions in the solid catalyst. The treatment is done prior to the activation and use of the catalyst in a suitable reactor system. ‘The beneficial effects seen are: a higher content of olefins in the hydrocarbon product and a higher fraction of alpha olefins in the olefins produced. The effects are seen especially with iron catalysts that have been pre-treated with potassium.
Various other structural and catalytic effects are also seen and these are attributed to the effects induced by microwave treatment.
FR
S11 -
Effects with other catalysts capable of absorbing microwave radiation may also be anticipated.
The results indicate that there is an optimum microwave exposure power level, duration and bed shape and these parameters can be determined fairly simply by a person skilled in the art by experimentation.
Claims (21)
1. A process for improving efficiency of a microwave absorbing catalyst comprising delivering, to said catalyst, a predetermined dose of microwave radiation, the dose being determined to impart optimum efficiency to the catalyst.
2. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 1 in which the microwave radiation is delivered to the catalyst by placing the catalyst in a microwave radiation field.
3. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 2 in which the dose of microwave radiation delivered to the catalyst is a function of the time the catalyst is placed in the field.
4. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 2 in which the dose of microwave radiation delivered to the catalyst is a function of the field power of the microwave radiation field.
5. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 2 in which the dose of microwave radiation delivered to the catalyst is a function of the time the catalyst is placed in the field and the field power of the microwave radiation field.
6. A process for improving efficiency of a microwave absorbing catalyst as claimed in any one of the preceding claims in which the catalyst is a cobalt based catalyst.
7. A process for improving efficiency of a microwave absorbing catalyst as claimed in any one of claims 1 to 5 in which the catalyst is an iron based catalyst.
. LC . , ~=
8. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 7 in which the catalyst is a calcined Fe/SiO; catalyst.
9. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 8 in which the Fe/SiO; is calcined by subjecting it to an elevated temperature.
10. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 9 in which the Fe/SiO, is calcined by subjecting it to a temperature of about 650°C for about 3 hours.
11. A process for improving efficiency of a microwave absorbing catalyst as claimed in any one of claims 7 to 10 in which the iron-based catalyst is pretreated with an alkali metal.
12. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 11 in which the alkali metal is potassium.
13. A process for improving efficiency of a microwave absorbing catalyst as claimed in any one of the preceding claims in which the catalyst is for use in a Fischer-Tropsch process.
14. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 13 in which the efficiency of the catalyst is measured as a function of the olefin content in hydrocarbons produced by the Fischer- Tropsch process.
15. A process for improving efficiency of a microwave absorbing catalyst as claimed in claim 14 in which the efficiency of the catalyst is measured as a function of the alpha olefin content in hydrocarbons produced by the Fischer-Tropsch process.
vo
16. A process for improving efficiency of a microwave absorbing catalyst substantially as herein described with reference to and as exemplified by the accompanying examples.
17. A microwave absorbing catalyst which has been enhanced by a process as claimed in any one of the preceding claims.
18. A microwave absorbing catalyst as claimed in claim 17 in which the catalyst is a calcined iron based catalyst. ©
19. A microwave absorbing iron based catalyst as claimed in claim 18 in which the catalyst is Fe/SiO..
20. A microwave absorbing iron based catalyst as claimed in any one of claims 17 to 19 in which the catalyst is for use in a Fischer-Tropsch process.
21. A microwave absorbing iron based catalyst as claimed in claim 20 in which the efficiency of the catalyst is measured as a function of the olefin content, preferably the level of alpha olefin, in hydrocarbons produced by the Fischer-Tropsch process. DATED THIS 9™ DAY OF DECEMBER 2008. BOWMAN GILFILLAN INC. (JOHN & KERNICK) FOR THE APPLICANT
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200810397A ZA200810397B (en) | 2007-11-08 | 2008-12-09 | Improvement in the efficiency of catalysts |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200709650 | 2007-11-08 | ||
| ZA200810397A ZA200810397B (en) | 2007-11-08 | 2008-12-09 | Improvement in the efficiency of catalysts |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| ZA200810397B true ZA200810397B (en) | 2009-12-30 |
Family
ID=41727937
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ZA200810397A ZA200810397B (en) | 2007-11-08 | 2008-12-09 | Improvement in the efficiency of catalysts |
Country Status (1)
| Country | Link |
|---|---|
| ZA (1) | ZA200810397B (en) |
-
2008
- 2008-12-09 ZA ZA200810397A patent/ZA200810397B/en unknown
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Galvis et al. | Effects of sodium and sulfur on catalytic performance of supported iron catalysts for the Fischer–Tropsch synthesis of lower olefins | |
| Del Monte et al. | Effect of K, Co and Mo addition in Fe-based catalysts for aviation biofuels production by Fischer-Tropsch synthesis | |
| Suppiah et al. | Supported Metal Oxide Catalysts for CO2 Fischer–Tropsch Conversion to Liquid Fuels─ A Review | |
| Hayakawa et al. | Studies on precipitated iron catalysts for Fischer–Tropsch synthesis | |
| CA2746006C (en) | Olefin selective ft catalyst composition and preparation thereof | |
| Kang et al. | ZSM-5 supported iron catalysts for Fischer–Tropsch production of light olefin | |
| CA2889131C (en) | Process for preparing a fischer-tropsch catalyst | |
| Alayat et al. | Effect of synthesis and activation methods on the catalytic properties of silica nanospring (NS)-supported iron catalyst for Fischer-Tropsch synthesis | |
| CA2826520C (en) | A method of preparing a catalyst precursor | |
| US7419928B2 (en) | Fischer-Tropsch catalyst production | |
| EP3496856B1 (en) | A cobalt-containing catalyst composition | |
| CA2876042A1 (en) | Modified support material for fischer-tropsh synthesis catalyst | |
| CN101180124B (en) | Catalyst Manufacturing Method | |
| JP2006522685A (en) | Fischer-Tropsch catalyst production | |
| AU2012252072B2 (en) | A process for preparing a cobalt - containing hydrocarbon synthesis catalyst precursor | |
| Pan et al. | Fischer–Tropsch synthesis on Co/Al2O3 catalyst: effect of pretreatment procedure | |
| Kang et al. | Correlation of the amount of carbonaceous species with catalytic performance on iron-based Fischer–Tropsch catalysts | |
| Lee et al. | The Effect of cobalt loading on Fischer Tropsch synthesis over silicon carbide supported catalyst | |
| Kulikova et al. | Hydrocarbon synthesis from CO2 and H2 using the ultrafine iron-containing catalytic systems based on carbonized cellulose | |
| Van Steen et al. | Evaluation of molybdenum-modified alumina support materials for Co-based Fischer-Tropsch catalysts | |
| de Sousa et al. | Study of the effect of cobalt content in obtaining olefins and paraffins using the Fischer-Tropsch reaction | |
| ZA200810397B (en) | Improvement in the efficiency of catalysts | |
| Ribeiro et al. | Influence of sucrose addition and acid treatment of silica-supported Co-Ru catalysts for Fischer-Tropsch synthesis | |
| Park et al. | Effect of H2O on Slurry‐Phase Fischer–Tropsch Synthesis over Alumina‐supported Cobalt Catalysts | |
| Tavasoli et al. | Morphology and deactivation behaviour of Co–Ru/γ‐Al2O3 Fischer–Tropsch synthesis catalyst |