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Investigation of reforming catalyst deactivation by exposure to fly ash from biomass gasification in laboratory scale
Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
Bologna University, Italy.
Catator AB.
Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
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2007 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 21, no 5, p. 2481-2488Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2007. Vol. 21, no 5, p. 2481-2488
National Category
Energy Systems
Research subject
Chemistry, Biotechnology
Identifiers
URN: urn:nbn:se:vxu:diva-2765DOI: 10.1021/ef060633kOAI: oai:DiVA.org:vxu-2765DiVA, id: diva2:202721
Available from: 2007-12-14 Created: 2007-12-14 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Study of Catalyst Deactivation in Three Different Industrial Processes
Open this publication in new window or tab >>Study of Catalyst Deactivation in Three Different Industrial Processes
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Deactivation of catalysts were investigated focusing on three industrial processes: 1) Selective Catalytic Reduction (SCR) for abatement of NOx from biomass combustion using V2O5-WO3 /TiO2 catalysts; 2) Catalytic oxidation of volatile organic compounds (VOC) from printing industries using a Pt/γ-Al2O3 catalyst; and 3) Ni and Pt/Rh catalysts used in steam reforming reaction of bio-syngas obtained from biomass gasification.

The aim has been to simulate industrial conditions in laboratory experiments in order to comprehend influence of compounds affecting catalysts performance. Typical catalyst lifetimes in industrial processes are several years, which are a challenge when accelerating deactivation in laboratory scale experiments where possible exposure times are few hours or days. Catalysts can be introduced to deactivating compounds through different routes. The first method examined was gaseous exposure, which was applied to deactivate VOC oxidation catalyst through exposure of gaseous hexamethyldisiloxane. The second method involved wet impregnation and was used for impregnation of SCR catalyst with salt solutions. The third method was based on exposure and deposition of size selected particles of deactivating substances on the catalyst. The latter device was developed during this work. It was applied to monolithic SCR catalysts as well as to pellet catalysts intended for steam reforming of biomass gasification syngas. Deactivated SCR catalyst samples by size selected exposure method were verified and compared with SCR catalysts used in a commercial biomass boiler for 6 500 h.

Evaluations of fresh and deactivated samples were investigated using BET surface area; chemisorption and temperature programmed desorption (TPD); surface morphology using Scanning Electron Microscopy (SEM) and poison penetration profile through SEM with an Electron Micro Probe Analyser (EMPA) also equipped with a energy dispersive spectrometer (EDS); chemical analysis of accumulation of exposed compounds by Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES); and influence on catalyst performance. The size selected generated particles of deactivating substances were characterized with respect to mean diameter and number size distribution through Scanning Mobility Particle Sizer (SMPS) and mass size distribution applying an Electric Low Pressure Impactor (ELPI). Results from catalyst characterization methods were useful tools in evaluation of catalyst deactivation routes.

Understanding deactivation processes and impact on catalyst performance is vital for further optimization of catalysts with respect to performance and lifetime. Further research in this field can provide more resistant catalysts for application in industry leading to higher commercial benefits and further application of environmental catalysts in thermo-chemical conversion of biomass.

Place, publisher, year, edition, pages
Växjö: Växjö University Press, 2007
Series
Acta Wexionensia, ISSN 1404-4307 ; 106/2007
Keywords
deactivation, catalyst, SCR, VOC, steam reforming, aerosol particle, potassium, zinc, ash salts, biomass, organosilicon
National Category
Chemical Engineering
Research subject
Natural Science, Chemistry
Identifiers
urn:nbn:se:vxu:diva-1058 (URN)978-91-7636-533-5 (ISBN)
Public defence
2007-02-02, M1083, M, Växjö univsersitet, Växjö, 13:00
Opponent
Supervisors
Available from: 2007-02-01 Created: 2007-02-01 Last updated: 2017-02-24Bibliographically approved

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Einvall, JessicaLarsson, Ann-CharlotteBrandin, JanSanati, Mehri

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