| 1. |
- Sanati, Negin, et al.
(författare)
-
Growing interest in use of geographic information systems in health and healthcare research: a review of PubMed from 2003 to 2011.
- 2013
-
Ingår i: JRSM short reports. - : SAGE Publications. - 2042-5333. ; 4:6
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined There has been an increasing interest in applying GIS into health and healthcare research in recent years.4,5 However, this increasing interest has not yet been gauged. In order to address this, the current study was performed to examine the crude number and the annual rate of papers with ‘Geographic Information Systems’ among their MeSH Terms in PubMed (a free database which is maintained by US National Library of Medicine).
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Albertazzi, S, et al.
(författare)
-
The technical feasibility of biomass gasification for hydrogen production
- 2005
-
Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 106:1-4, s. 297-300
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification for energy or hydrogen production is a field in continuous evolution, due to the fact that biomass is a renewable and CO2 neutral source. The ability to produce biomass-derived vehicle fuel on a large scale will help to reduce greenhouse gas and pollution, increase the security of European energy supplies, and enhance the use of renewable energy. The Varnamo, Biomass Gassification Centre in Sweden is a unique plant and an important site for the development of innovative technologies for biomass transformation. At the moment, the Varnamo plant is the heart of the CHRISGAS European project, that aims to convert the produced gas for further upgrading to liquid fuels as dimethyl ether (DME), methanol or Fischer-Tropsch (F-T) derived diesel. The present work is an attempt to highlight the conditions for the reforming unit and the problems related to working with streams having high contents of sulphur and alkali metals.
|
|
| 5. |
- Andersson, Arne, et al.
(författare)
-
Direct Propane Ammoxidation to Acrylonitrile: Kinetics and Nature of the Active Phase
- 1993
-
Ingår i: New Frontiers in Catalysis (Studies in Surface Science and Catalysis ). - 0167-2991. ; 75, s. 691-705
-
Konferensbidrag (refereegranskat)abstract
- The kinetics of the direct synthesis of acrylonitrile from propane on V-Sb-Al-(W) mixed oxides indicate that acrylonitrile (ACN) forms by two parallel pathways, one directly from propane and the second, which is the prevalent path, through the intermediate formation of propylene (C3=). The limiting factor in the formation of ACN is the relative slowness of the step of allylic oxidation to ACN of the intermediate C3=, and the higher rate of C3= oxidation to carbon oxides as compared to that of ACN to COx. The step of C3= oxidation to ACN is controlled by the surface availability of NH3 which, in turn, depends considerably on the side reaction of NH3 oxidation to N2. The catalytic behavior of different modified V-Sb-(Al)-O systems and their characterization by X-ray diffraction analysis and Raman, Infrared and X-ray Photoelectron spectroscopies indicate that i) a reduction of both V and Sb occurs during the catalytic reaction, ii) the presence of vanadium not stabilized in the rutile-like phase is responsible for the side reaction of NH3 oxidation and lowering of the selectivity, iii) alumina reacts with antimony forming an AlSbO4 rutile phase which could be epitaxially intergrown or in solid solution with the VSbO4/Sb2O4 system, which, in turn, limits the presence of not stabilized (unselective) vanadium species, and iv) antimony oxide supported on alumina is also selective in propane ammoxidation, but forming acetonitrile as the main product. The doping with vanadium of this sample increases slightly the activity, but especially gives rise to the formation of acrylonitrile instead of acetonitrile.
|
|
| 6. |
- Andersson, Arne, et al.
(författare)
-
Structure-Activity Relationships in the Oxidation of Alkylaromatics over Metal Oxides
- 1991
-
Ingår i: Studies in Surface Science and Catalysis. - 0167-2991. ; 67, s. 43-55
-
Tidskriftsartikel (refereegranskat)abstract
- In order to accomplish oxidation of alkylaromatic compounds, both cations, which serve as adsorption centers, and oxygen species of suitable bond strength are needed. When compared to partial oxidation, relatively weakly bonded oxygen species are involved in combustion. On the basis of these criteria, using a simple model of the active ensemble, a relationship between reaction rate and bond strength is derived for partial and total oxidation. Its applicability is demonstrated using data for the oxidation of toluene over a large number of binary metal oxides. Some characteristic features following from the model are discussed, considering catalytic results on the structure sensitivity of oxidation and ammoxidation reactions over crystalline V,O and MOO,. Furthermore, kinetic results on the oxidation of toluene to benzaldehyde and carbon oxides in presence of ammonia, which serves as an electron donor to the catalyst surface, demonstrate that the oxygen species taking part in partial oxidation and combustion are nucleophilic and electrophilic in character, respectively.
|
|
| 7. |
- Andersson, Arne, et al.
(författare)
-
Surface Characterization and Reactivity in Ammoxidation Reactions of Vanadium Antimonate Catalysts
- 1994
-
Ingår i: Applied Catalysis A: General. - 0926-860X. ; 113:1, s. 43-57
-
Tidskriftsartikel (refereegranskat)abstract
- Unsupported vanadium antimonate catalysts with Sb/V ratios of 1 and 5 and samples with the latter ratio supported on alumina were studied in toluene and propane ammoxidation to benzonitrile and acrylonitrile, respectively, and were characterized by X-ray photoelectron spectroscopy (XPS) analysis before and after catalytic tests. Activity data for toluene ammoxidation suggest that excess antimony with respect to the stoichiometric amount required for forming the VSbO4 rutile phase affects the dispersion of the latter phase giving smaller particles. Vanadium sites are involved both in the activation of toluene and in the insertion of nitrogen in this reaction, whereas antimony does not play a specific role in the reaction mechanism. In propane ammoxidation, on the other hand, due to a higher reaction temperature with respect to toluene (500°C vs. 370°C), free vanadia on the surface of the catalyst has a negative influence on the selectivity because it promotes the conversion of ammonia to nitrogen, decreasing the surface nitrogenous species required for the selective formation of acrylonitrile. Excess antimony is thus necessary for completing the reaction between antimony and vanadium oxides, but antimony also participates in the reaction mechanism. In propane ammoxidation, in fact, XPS data show that both vanadium and antimony sites are reduced. Tentatively, vanadium sites are involved in the activation of propane, while antimony sites insert nitrogen. The differences between the toluene and propane ammoxidation mechanisms are interpreted to be primarily related to the different reaction temperatures.
|
|
| 8. |
- Arnby, Karl, 1974, et al.
(författare)
-
Characterization of Pt/γ-Al2O3 catalysts deactivated by hexamethyldisiloxane
- 2004
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 54:1, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- The deactivation of alumina supported platinum and iron catalysts by hexamethyldisiloxane (HMDS) exposure has been investigated. Three catalysts (Pt/Al2O3, Fe/Al2O3 and Fe/Pt/Al2O3) were prepared and the influence of short- and long-term deactivation on the activity for oxidation of ethyl acetate was studied. The catalysts were characterized using BET, ICP-AES, XPS, SEM and CO chemisorption. The deactivation was found to proceed by deposition of silicon-species in form of silicate (SixOy) that block the active sites on the surface of the catalysts. The silicon seems to rather attach to platinum and iron sites than to the alumina surface. The Pt/Al2O3 catalyst was moderately deactivated by HMDS even though the silicate was blocking almost the entire platinum surface. Adding iron to the catalyst increased the tolerance towards HMDS as fewer Pt sites were blocked for the Fe/Pt/Al2O3 sample. The deactivation of the two platinum containing samples was reversible since the silicate could partly be removed from the Pt sites by regeneration whereby most of the activity was restored. However, for the Fe/Al2O3 sample the deactivation was more severe and irreversible.
|
|
| 9. |
- Augustsson, Ola
(creator_code:cre_t)
-
A catalyst for catalytic oxidation of hydrocarbons
- 2004
-
Patent (övrigt vetenskapligt/konstnärligt)abstract
- A catalyst having resistance towards Si and/or P deactivation in catalytic oxidation of organic hydrocarbons is disclosed. The catalyst comprises a catalytically inert support, a catalytically active layer of metallic Pt and/or Pd and deposited on said catalytically active layer at least one oxide ...
|
|
| 10. |
- Bagherpour, Mohammad Bagher, et al.
(författare)
-
Effects of irrigation and water content of packings on alpha-pinene vapours biofilteration performance
- 2005
-
Ingår i: Biochemical engineering journal. - : Elsevier. - 1369-703X .- 1873-295X. ; 24:3, s. 185-193
-
Tidskriftsartikel (refereegranskat)abstract
- The main objective of this investigation is to determine the effect of different physical parameters on the performance of biofilters, treating hydrophobic compounds. In this respect, the effects of irrigation and water content of packings on the removal efficiency of bed in different pollutant loading rates, and gas phase flow rates, is studied. Alpha-pinene, which is produced from variety of industrial wood products, pulp and paper industries, and fragrance production units, has been selected as a model compound. Since the effectiveness of biofiltration depends strongly upon water solubility of compounds, in the case of alpha-pinene (2.5 ppm, at 25 ◦C), the process of waste gas treatment is faced with difficulties. In this paper, it is shown that performance of biofilters, treating hydrophobic contaminants, declines due to irrigation. This reduction is detected by an increase in the outlet concentration from 11% up to 22.5%. Its magnitude depends on the gas velocity inside the biofilter and outlet concentration of the bed. The result indicated that pore blocking along the bed has less effect on the performance reduction than diffusion coefficient. Also the inhibitory effects of velocity on biodegradation are considerably higher than the effects of concentration. In addition, this compost-based biofilter shows noteworthy higher elimination capacities in comparison with previous studied biofiltration systems. In this study, a maximum elimination capacity of 227 gm−3 of packing h−1 is achieved by 95% of removal efficiency. The maximum concentration in the inlet gas was 650 mgm−3.
|
|
| 11. |
- Bengtsson, Peter, 1974-, et al.
(författare)
-
Evaluation of hydrocarbon emissions from heart- and sapwood of Scots pine using a laboratory-scale wood drier
- 2004
-
Ingår i: Holzforschung. - : Walter de Gruyter. - 1437-434X .- 0018-3830. ; 58:6, s. 660-665
-
Tidskriftsartikel (refereegranskat)abstract
- The subject of study is the emission of Volatile Organic Compounds (VOC) during the drying of wood. Heartwood and sapwood from Scots pine were dried at different temperatures (50, 70 and 90°C) in a laboratory kiln. The sampling method, Solid Phase Microextraction was used to collect the different volatile organic compounds during the drying. The gas chromatograph and mass spectrometer was used to identify and quantify the organic matter. The total hydrocarbons were measured with a flame ionization detector. Primarily, different monoterpenes were released during the drying process. 3-carene and α-pinene were most common and were also analytically quantified. The diterpene, pimaral, was found in an estimated large amount in the later stage of the drying process but was not exactly quantified. Large differences in both release behaviour and total amount of released hydrocarbon between heart- and sapwood were obtained. Emissions of VOC from heartwood were of a magnitude approximately three times higher than that from sapwood.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Bladh, Henrik, et al.
(författare)
-
Influence of Soot Particle Aggregation on Time-Resolved Laser-Induced Incandescence Signals
- 2011
-
Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 104:2, s. 331-341
-
Tidskriftsartikel (refereegranskat)abstract
- Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by transmission electron microscopy (TEM), a scanning mobility particle sizer (SMPS) and an aerosol particle mass analyzer coupled in series after a differential mobility analyzer (DMA-APM). Despite nearly identical primary particle size distributions for three selected operating conditions, LII measurements resulted in signal decays with significant differences in decay rate. However, the three cases were found to have quite different levels of aggregation as shown both in TEM images and mobility size distributions, and the results agree qualitatively with the expected effect of diminished heat conduction from aggregated particles resulting in longer LII signal decays. In an attempt to explain the differences quantitatively, the LII signal dependence on aggregation was modelled using a heat and mass transfer model for LII given the primary particle and aggregate size distribution data as input. Quantitative agreement was not reached and reasons for this discrepancy are discussed.
|
|
| 15. |
- Blomqvist, Per, et al.
(författare)
-
An experimental study of spontaneous ignition in storages of wood pellets
- 2007
-
Ingår i: 10th International Conference - Fire and Materials 2007.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This article focuses on experimental studies of self-heating characteristics of wood pellets. Controlled experiments have been conducted in physical scales from 1 dm3 to 4 m3 with wood pellets. Basket tests have been conducted according to the "crossing-point method" to derive kinetic data on the exothermic reactions responsible for self-heating and eventually spontaneous ignition. The kinetic data was used in the planning of the large-scale experiments for predictions of approximate critical temperatures. The experiments in the 1 m3 scale were set-up basically as an enlargement of the basket tests to obtain validation experiments with controlled boundary conditions in a reasonable large scale. Several experiments were conducted and spontaneous ignition was seen in the centre of the pellet bulk at an ambient temperature of 115C. The close to real-scale experiments with 4 m3 wood pellets filled in a 6 m high silo were not strictly self heating experiments, instead a core shaped heating element was allowed to initiate the pyrolysis in the pellets. Heat and gas production and transportation from the growing pyrolysis zone were mapped with a large number of measurement points in the pellets bulk and in the top of the silo. The experimental work conducted gave kinetic data on the exothermic reactions in wood pellets, insight in self heating processes, a link between different experimental scales and knowledge regarding possibilities for detection of fires in storages of wood pellets.
|
|
| 16. |
- Blomqvist, Per, et al.
(författare)
-
Fires in storages of biofuels
- 2007
-
Ingår i: Fire and Materials 2007 Proceedings.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- 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.
|
|
| 24. |
- Gustafsson, Eva, et al.
(författare)
-
Measurement of Aerosol Particles from Steam and Oxygen Blown Gasification of Wood Pellets in a 20 kW Atmospheric Bubbling Fluidised Bed (ABFB) Gasifier
- 2007
-
Ingår i: 15th European Biomass Conference & Exhibition. - : ETA-Renewable Energies and WIP-Renewable Energies. ; , s. 1128-1130
-
Konferensbidrag (refereegranskat)abstract
- In the present study, the particle number and mass size distributions from two measurements on steam and oxygen blown atmospheric bubbling fluidised bed (ABFB) gasification (20 kW) of wood pellets are presented. The total particle number concentration determined using a scanning mobility particle sizer (SMPS) varied between 5.1x10^5-6.6x10^6 particles/cm3 (mobility equivalent diameter (dB) 10-670 nm), with the largest variation for particles with dB<100 nm. The particle number size distributions were bimodal with modes at 20-30 nm and at 260-410 nm. The particle mass concentrations determined using a low pressure impactor (LPI) varied between 60-310 mg/m3 for particles with aerodynamic diameter (dae)<5 µm, with modes at 0.2-0.3 µm and at 2-3 µm.
|
|
| 25. |
- Gustafsson, Eva, et al.
(författare)
-
Physical and Chemical Characterization of Aerosol Particles Formed during the Thermochemical Conversion of Wood Pellets Using a Bubbling Fluidized Bed Gasifier
- 2007
-
Ingår i: Energy Fuels. - : American Chemical Society, Washington DC. - 0887-0624 .- 1520-5029. ; 21:6, s. 3660-3667
-
Tidskriftsartikel (refereegranskat)abstract
- Product gas obtained through biomass gasification can be upgraded to hydrogen-rich synthesis gas. The synthesis gas can be further converted to liquid or gaseous fuels. However, the raw product gas contains both gas- and particle-phase impurities that can negatively affect both catalysts and hot-gas filters used for upgrading and cleaning. The present study aimed to characterize, both physically and chemically, aerosol particles formed during the steam- and oxygen-blown biomass gasification of wood pellets in an atmospheric 20 kW bubbling fluidized bed (BFB) gasifier. The product gas from the gasifier was sampled upstream from the cyclone at 500 °C. The particle number size distribution determined using a scanning mobility particle sizer (SMPS) was bimodal, with modes at 20–30 and 400 nm, mobility equivalent diameters (dB). The total mean number concentration of particles with dB = 15–670 nm was approximately 7 × 10^5 particles/cm3; however, the concentration of particles with dB < 80 nm fluctuated. The particle mass size distribution determined using a low-pressure impactor (LPI) was bimodal, and the total mass concentration of particles with aerodynamic diameters (dae) < 5 µm was 310 mg/m3. Microscopy analysis of particulate matter on the lower LPI stages, expected to sample particles with dae < 0.4 µm, revealed structures approximately 10 µm in diameter. In addition, the mass concentration of particles with dae < 0.5 µm determined using a LPI was higher than that estimated using a SMPS, possibly because of the bounce-off or re-entrainment of coarser particles from higher LPI stages. Elementary analysis of the particulate matter indicated that it was dominated by carbon. The collected particulate matter was stable when heated in nitrogen to 500 °C, indicating that the carbon was not present as volatile tars but more likely as char or soot. The particulate matter collected on all LPI stages contained a small percentage of ash (noncarbonaceous inorganic material), with calcium as the dominant element.
|
|
