| 1. |
- Einvall, Jessica, et al.
(författare)
-
Investigation of reforming catalyst deactivation by exposure to fly ash from biomass gasification in laboratory scale
- 2007
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 21:5, s. 2481-2488
-
Tidskriftsartikel (refereegranskat)abstract
- Production of synthesis gas by catalytic reforming of product gas from biomass gasification can lead to catalyst deactivation by the exposure to ash compounds present in the flue gas. The impact of fly ash from biomass gasification on reforming catalysts was studied at the laboratory scale. The investigated catalyst was Pt/Rh based, and it was exposed to generated K2SO4 aerosol particles and to aerosol particles produced from the water-soluble part of biomass fly ash, originating from a commercial biomass combustion plant. The noble metal catalyst was also compared with a commercial Ni-based catalyst, exposed to aerosol particles of the same fashion. To investigate the deactivation by aerosol particles, a flow containing submicrometer-size selected aerosol particles was led through the catalyst bed. The particle size of the poison was measured prior to the catalytic reactor system. Fresh and aerosol particle exposed catalysts were characterized using BET surface area, XRPD (X-ray powder diffraction), and H2 chemisorption. The Pt/Rh catalyst was also investigated for activity in the steam methane reforming reaction. It was found that the method to deposit generated aerosol particles on reforming catalysts could be a useful procedure to investigate the impact of different compounds possibly present in the product gas from the gasifier, acting as potential catalyst poisons. The catalytic deactivation procedure by exposure to aerosol particles is somehow similar to what happens in a real plant, when a catalyst bed is located subsequent to a biomass gasifier or a combustion boiler. Using different environments (oxidizing, reducing, steam present, etc.) in the aerosol generation adds further flexibility to the suggested aerosol deactivation method. It is essential to investigate the deactivating effect at the laboratory scale before a full-scale plant is taken into operation to avoid operational problems.
|
|
| 2. |
- Larsson, Ann-Charlotte, et al.
(författare)
-
Deactivation of SCR Catalysts by Exposure to Aerosol Particles of Potassium and Zinc Salts
- 2007
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 41:4, s. 369-379
-
Tidskriftsartikel (refereegranskat)abstract
- Generated aerosol particle deposition has been applied in laboratory scale to induce deactivation of commercial Selective Catalytic Reduction (SCR) catalysts Of V2O5-WO3/TiO2 monolithic type. The monolithic catalyst has been exposed to the generated submicrometer particle of inorganic salts, KCl, K2SO4, and ZnCl2 at 200 degrees C in a tubular reactor. The generated particles have been deposited on the catalytic surfaces by utilization of an electrostatic field. Physical characterization of the generated aerosol particles were conducted by Scanning Mobility Particle Sizer (SMPS) and Electric Low Pressure Impactor (ELPI) with and without catalyst in order to investigate the magnitude of the particle deposition. Particle charge distribution was also evaluated with a Tandem Differential Mobility Analyser (TDMA) set up.SCR is the most common method to commercially reduce NOx emissions from combustion processes. Catalyst lifetime is important for process economics and extending catalyst life can allow future strengthened emission legislation and diminished NOx emissions.Verification of particle deposition has been conducted through comparison with catalyst samples exposed to commercial biomass combustion condition.The reactivity of both fresh and exposed catalyst samples as well as commercially used samples was examined in SCR reaction and the methods of deposition as well as the influence of the different salts on catalytic performance have been explored.Catalyst samples have been evaluated with Scanning Electron Microscopy (SEM) with respect to surface morphology of the catalyst material. The laboratory deactivated catalyst samples showed resemblance with the commercially exposed catalyst sample with respect to salts concentration and deposition of the salts particles. The obtained influence on catalyst activity was comparable with commercially obtained catalyst activity reductions at comparable potassium concentration levels.
|
|
| 3. |
- Larsson, Ann-Charlotte, et al.
(författare)
-
Physical and chemical characterisation of potassium deactivation of a SCR catalyst for biomass combustion
- 2007
-
Ingår i: Topics in catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 45:1-4, s. 149-152
-
Tidskriftsartikel (refereegranskat)abstract
- The deactivation of a commercial Selective Catalytic Reduction (SCR) catalyst, of V2O5-WO3/TiO2 type, has been studied through comparisons with results from a full-scale biomass combustion plant to that with laboratory experiments. In the latter, the catalyst was exposed to KCl and K2SO4 by both wet impregnation with diluted salt solutions and deposition of generated submicrometer aerosol particles by means of an electrostatic field. The reactivity of fresh and deactivated samples was examined in the SCR reaction. Chemical and physical characterizations were focusing on internal structures and chemical composition. Deposition of submicrometer sized particles on the monolithic SCR catalyst was shown to induce deactivation with characteristics resembling those obtained in a commercial biomass combustion plant.
|
|
| 4. |
- Larsson, Ann-Charlotte, et al.
(författare)
-
Pilot-scale investigation of Pt/alumina catalysts deactivation by organosilicon in the total oxidation of hydrocarbons
- 2007
-
Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 45:1-4, s. 121-124
-
Tidskriftsartikel (refereegranskat)abstract
- The deactivation of alumina-supported platinum catalyst for VOC oxidation by long-term exposure for hexamethyldisiloxane (HMDS) has been investigated in a pilot scale reactor for up to 1000 h of exposure. Catalyst samples were characterized by ICP-AES, BET and silicon deposition by SEM. Catalyst activity was investigated using oxidation of ethyl acetate showing deactivation of the catalyst samples as exposed to HMDS increasing with exposure time. Silicon was shown to deposit on the catalyst as well as on the blank alumina support. SEM investigation of an individual pellet revealed a radial eggshell silicon distribution. CO chemisorption showed strong decrease of Pt active sites after deactivation, while still maintaining reasonable oxidation levels of ethyl acetate.
|
|
