| 1. |
- Basile, Francesco, et al.
(författare)
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Steam reforming of hot gas from gasified wood types and miscanthus biomass
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 35:Supplement 1, s. S116-S122
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Tidskriftsartikel (refereegranskat)abstract
- The reforming of hot gas generated from biomass gasification and high temperature gas filtration was studied in order to reach the goal of the CHRISGAS project: a 60% of synthesis gas (as x(H2)+ x(CO) on a N2 and dry basis) in the exit gas, which can be converted either into H2 or fuels. A Ni-MgAl2O4 commercial-like catalyst was tested downstream the gasification of clean wood made of saw dust, waste wood and miscanthus as herbaceous biomass. The effect of the temperature and contact time on the hydrocarbon conversion as well as the characterization of the used catalysts was studied. Low (<600 °C), medium (750°C–900 °C) and high temperature (900°C–1050 °C) tests were carried out in order to study, respectively, the tar cracking, the lowest operating reformer temperature for clean biomass, the methane conversion achievable as function of the temperature and the catalyst deactivation. The results demonstrate the possibility to produce an enriched syngas by the upgrading of the gasification stream of woody biomass with low sulphur content. However, for miscanthusthe development of catalysts with an enhanced resistance to sulphur poison will be the key point in the process development.
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| 2. |
- Brandin, Jan, 1958-, et al.
(författare)
-
A review of thermo-chemical conversion of biomass into biofuels-focusing on gas cleaning and up-grading process steps
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- It is not easy to replace fossil-based fuels in the transport sector, however, an appealing solution is to use biomass and waste for the production of renewable alternatives. Thermochemical conversion of biomass for production of synthetic transport fuels by the use of gasification is a promising way to meet these goals.One of the key challenges in using gasification systems with biomass and waste as feedstock is the upgrading of the raw gas produced in the gasifier. These materials replacing oil and coal contain large amounts of demanding impurities, such as alkali, inorganic compounds, sulphur and chlorine compounds. Therefore, as for all multi-step processes, the heat management and hence the total efficiency depend on the different clean-up units. Unfortunately, the available conventional gas filtering units for removing particulates and impurities, and also subsequent catalytic conversion steps have lower optimum working temperatures than the operating temperature in the gasification units.This report focuses on on-going research and development to find new technology solutions and on the key critical technology challenges concerning the purification and upgrading of the raw gas to synthesis gas and the subsequent different fuel synthesis processes, such as hot gas filtration, clever heating solutions and a higher degree of process integration as well as catalysts more resistant towards deactivation. This means that the temperature should be as high as possible for any particular upgrading unit in the refining system. Nevertheless, the temperature and pressure of the cleaned synthesis gas must meet the requirements of the downstream application, i.e. Fischer-Tropsch diesel or methanol.Before using the gas produced in the gasifier a number of impurities needs to be removed. These include particles, tars, sulphur and ammonia. Particles are formed in gasification, irrespective of the type of gasifier design used. A first, coarse separation is performed in one or several cyclone filters at high temperature. Thereafter bag-house filters (e.g. ceramic or textile) maybe used to separate the finer particles. A problem is, however, tar condensation in the filters and there is much work performed on trying to achieve filtration at as high a temperature as possible.The far most stressed technical barriers regarding cleaning of the gases are tars. To remove the tar from the product gas there is a number of alternatives, but most important is that the gasifier is operated at optimal conditions for minimising initial tar formation. In fluid bed and entrained flow gasification a first step may be catalytic tar cracking after particle removal. In fluid bed gasification a catalyst, active in tar cracking, may be added to the fluidising bed to further remove any tar formed in the bed. In this kind of tar removal, natural minerals such as dolomite and olivine, are normally used, or catalysts normally used in hydrocarbon reforming or cracking. The tar can be reformed to CO and hydrogen by thermal reforming as well, when the temperature is increased to 1300ºC and the tar decomposes. Another method for removing tar from the gas is to scrub it by using hot oil (200-300ºC). The tar dissolves in the hot oil, which can be partly regenerated and the remaining tar-containing part is either burned or sent back to the gasifier for regasification.Other important aspects are that the sulphur content of the gas depends on the type of biomass used, the gasification agent used etc., but a level at or above 100 ppm is not unusual. Sulphur levels this high are not acceptable if there are catalytic processes down-stream, or if the emissions of e.g. SO2 are to be kept down. The sulphur may be separated by adsorbing it in ZnO, an irreversible process, or a commercially available reversible adsorbent can be used. There is also the possibility of scrubbing the gas with an amine solution. If a reversible alternative is chosen, elementary sulphur may be produced using the Claus process.Furthermore, the levels of ammonia formed in gasification (3,000 ppm is not uncommon) are normally not considered a problem. When combusting the gas, nitrogen or in the worst case NOx (so-called fuel NOx) is formed; there are, however, indications that there could be problems. Especially when the gasification is followed by down-stream catalytic processes, steam reforming in particular, where the catalyst might suffer from deactivation by long-term exposure to ammonia.The composition of the product gas depends very much on the gasification technology, the gasifying agent and the biomass feedstock. Of particular significance is the choice of gasifying agent, i.e. air, oxygen, water, since it has a huge impact on the composition and quality of the gas, The gasifying agent also affects the choice of cleaning and upgrading processes to syngas and its suitability for different end-use applications as fuels or green chemicals.The ideal upgraded syngas consists of H2 and CO at a correct ratio with very low water and CO2 content allowed. This means that the tars, particulates, alkali salts and inorganic compounds mentioned earlier have to be removed for most of the applications. By using oxygen as the gasifying agent, instead of air, the content of nitrogen may be minimised without expensive nitrogen separation.In summary, there are a number of uses with respect to produced synthesis gas. The major applications will be discussed, starting with the production of hydrogen and then followed by the synthesis of synthetic natural gas, methanol, dimethyl ether, Fischer-Tropsch diesel and higher alcohol synthesis, and describing alternatives combining these methods. The SNG and methanol synthesis are equilibrium constrained, while the synthesis of DME (one-step route), FT diesel and alcohols are not. All of the reactions are exothermal (with the exception of steam reforming of methane and tars) and therefore handling the temperature increase in the reactors is essential. In addition, the synthesis of methanol has to be performed at high pressure (50-100 bar) to be industrially viable.There will be a compromise between the capital cost of the whole cleaning unit and the system efficiency, since solid waste, e.g. ash, sorbents, bed material and waste water all involve handling costs. Consequently, installing very effective catalysts, results in unnecessary costs because of expensive gas cleaning; however the synthesis units further down-stream, especially for Fischer-Tropsch diesel, and DME/methanol will profit from an effective gas cleaning which extends the catalysts life-time. The catalyst materials in the upgrading processes essentially need to be more stable and resistant to different kinds of deactivation.Finally, process intensification is an important development throughout chemical industries, which includes simultaneous integration of both synthesis steps and separation, other examples are advanced heat exchangers with heat integration in order to increase the heat transfer rates. Another example is to combine exothermic and endothermic reactions to support reforming reactions by using the intrinsic energy content. For cost-effective solutions and efficient application, new solutions for cleaning and up-grading of the gases are necessary.
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| 3. |
- Brandin, Jan, 1958-, et al.
(författare)
-
Aerosolkatalysatorer för industriell gasrening
- 2016
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Rapport (refereegranskat)abstract
- Aerosol catalysts – small particles (with aerodynamic diameter up to 100 m) of catalytically active material suspended in gas – were examined for the intended use of NOx reduction with ammonia (SCR) in smaller industrial plants and boilers as an alternative to SNCR. The aerosol particles are intended to be injected into the flue gas at high temperature, together with ammonia/urea, and then separated on a particulate filter (bag‐type filter) at low temperature. The NOx reduction can occur during the pneumatic transport in the boiler or/and on the catalytically active filter cake. The catalysts must have sufficiently high activity in order to keep down their consumption, they must be cheap enough to be used as a consumable item, and must be harmless to humans and the environment. Two materials were developed during the work as possible candidates: natural zeolites and a FeSO4/activated carbon‐based catalyst. Cost estimates, for a hypothetical 1 MWth plant, shows that a NOx reduction close to 50% economically justify the introduction of SNCR for small plants (<25 GWh, NOx reductions levels between 30‐50% and 2 in stoichiometric ratio), both for the use of urea and liquid anhydrous ammonia with the percent NOx fee of 50 SEK/kg. The result is modest, at best 15‐20% cost reduction compared to no action. Raised tariffs to 60 SEK/kg NOx will improved the situation, but the results are still modest. When the aerosol catalysts was used in the cost estimate, and an assumed NOx reduction degree of 85% was supposed to be reached, good results were obtained at low catalyst costs (0.5‐2 SEK/kg). However the plant can handle at most a cost of 4 SEK/kg. Estimated cost for the aerosol catalyst is in the range of 10 SEK/kg. In order to be economically attractive, the catalyst should be recycled, thereby lowering the cost of catalyst consumption.
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| 4. |
- Brandin, Jan, 1958-, et al.
(författare)
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Deactivation and Characterization of SCR Catalysts Used in Municipal Waste Incineration Applications
- 2018
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Ingår i: Catalysis Letters. - : Springer. - 1011-372X .- 1572-879X. ; 148:1, s. 312-327
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Tidskriftsartikel (refereegranskat)abstract
- Catalysts used for selective catalytic reduction were deactivated for various times in a slipstream from a municipal solid waste incineration plant and then characterized. The activity for NO reduction with NH3 was measured. The Brunauer–Emmett–Teller surface areas were determined by N2 adsorption from which the pore size distributions in the mesopore region were obtained. Micropore areas and volumes were also obtained. The composition of fresh and deactivated catalysts as well as fly ash was determined by atomic absorption spectroscopy and scanning electron microscopy with energy dispersive X-ray analysis. The changes in surface area (8% decrease in BET surface area over 2311 h) and pore structure were small, while the change in activity was considerable. The apparent pre-exponential factor was 1.63 × 105 (1/min) in the most deactivated catalyst, compared to 2.65 × 106 (1/min) in the fresh catalyst, i.e. a reduction of 94%. The apparent activation energy for the fresh catalyst was 40 kJ/mol, decreasing to 27 kJ/mol with increasing deactivation. Characterization showed that catalytic poisoning is mainly due to decreased acidity of the catalyst caused due to increasing amounts of Na and K.
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| 5. |
- Brandin, Jan, 1958-, et al.
(författare)
-
Green LPG
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The use of energy gases with renewable origins will become important with diminishing fossil resources. This as the infrastructure of the gaseous fuels is well built out and the distribution networks already exist. LPG is one of the most versatile fuels around, perfect for rural areas and in many other applications. The fossil origin of the fuel will, in today’s climate and environmental debate, however position it as a thing of the past and not part of the future energy supply. The technology and development performed under this and previous programs with the Swedish Gas Centre will however suggest a way to bridge this conception and make LPG a part of the future energy mix. A good starting point for two and three carbon energy gases is glycerine, with its three carbon backbone. The reason for focusing on glycerine is its benign chemical nature, it is:• Harmless from a toxic standpoint• Chemically inert• Non-corrosive• Relatively high energy density• Zero carbon dioxide emissions It is also readily available as the production of biofuels (from which glycerine is a sideproduct) in the world has increased markedly over the last 10 year period. This glut in the glycerol production has also lowered worldwide prices of glycerine.Since the key step in producing energy gases from glycerol is the dehydration of glycerol to acrolein, this step has attracted much attention during the development work. The step has been improved during the performed work and the need for any regeneration of the catalyst has been significantly reduced, if not omitted completely. This improvement allows for a simple fixed bed reactor design and will save cost in reactor construction as well as in operating costs of the plant. The same conclusion can be drawn from the combination of the two functionalities (dehydration and hydrogenation) in designing a catalyst that promote the direct reaction of 1-propanol to propane in one step instead of two. The experiments with the decarbonylation of acrolein to form ethane show that the catalyst deactivation rates are quite rapid. The addition of noble metal to the catalyst seems to improve the longevity of the catalyst, but the coking is still too severe to provide for a commercially viable process. It is believed that there is a possible way forward for the decarbonylation of acrolein to ethane; it will however require additional time and resources spent in this area. In this work it has been shown that all of the catalytic steps involved in the production of propane from glycerol have sufficient longterm stability and endurance and it is motivated to recommend that the project continues to pilot plant testing stage.
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| 6. |
- Brandin, Jan, 1958-, et al.
(författare)
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High-temperature and high concentration SCR of NO with NH3 : application in a CCS process for removal of carbon dioxide
- 2012
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 191, s. 218-227
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates several commercial selective catalytic reduction (SCR) catalysts (A–E) for application in a high-temperature (approximately 525 °C) and high-concentration (5000 ppm NO) system in combination with CO2 capture. The suggested process for removing high concentrations of NOx seems plausible and autothermal operation is possible for very high NO concentrations. A key property of the catalyst in this system is its thermal stability. This was tested and modelled with the general power law model using second-order decay of the BET surface area with time. Most of the materials did not have very high thermal stability. The zeolite-based materials could likely be used, but they too need improved stability. The SCR activity and the possible formation of the by-product N2O were determined by measurement in a fixed-bed reactor at 300–525 °C. All materials displayed sufficiently high activity for a designed 96% conversion in the twin-bed SCR reactor system proposed. The amount of catalyst needed varied considerably and was much higher for the zeolithic materials. The formation of N2O increased with temperature for almost all materials except the zeolithic ones. The selectivity to N2 production at 525 °C was 98.6% for the best material and 95.7% for the worst with 1000 ppm NOx in the inlet; at 5000 ppm NOx, the values were much better, i.e., 98.3 and 99.9%, respectively.
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| 7. |
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| 8. |
- Brandin, Jan, 1958-, et al.
(författare)
-
Multi-function catalysts for glycerol upgrading
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During the last three years Biofuel-Solution, a privately held Swedish entity, has developed an IP-portfolio around gas-phase glycerol conversion into medium-value chemicals. The targeted chemicals have large to very large markets, to allow for use by more than a fraction of the glycerol available today without impacting the cost of the product. The reason behind is that glycerol is a by-product from the biofuel industry, including biodiesel and bioethanol. This indicates large production volumes, even though the glycerol is a fraction of the fuel produced. A by-product from any fuel process will be vast and therefore any chemical produced from this side-product will have to have a large market to offset it to. In order to avoid changing the fundamental market behavior, similar to what the biodiesel industry has done to the glycerol market. In the course of this work, several end-products have been targeted. These include plastic monomers, mono-alcohols and energy gases; using acrolein as a common starting point. To produce chemicals with high purity and efficiency, selective and active catalysts are required. For instance, a process for producing propionaldehyde and n-propanol has been developed to the point of demonstration and commercialization building on the gas-phase platform. By developing multi-function catalysts which perform more than one task simultaneously, synergies can be reached that cannot be achieved with traditional catalysts. For instance, by combining catalyst functionalities, reactions that are both endothermic and exothermic can be performed simultaneously. This mean lower inlet reactor temperatures (in this particular case) and a more even temperature distribution. By performing the dehydration of glycerol to acrolein in combination with another, exothermal reaction by-products can be suppressed and yields increased. It also means that new reaction pathways can be achieved, allowing for new ways to produce chemicals and fuels from glycerol. As in the case of ethane production from acrolein, where a catalyst surface has been devised where acrolein is first adsorbed. The actual mechanism is unknown but in speculation, the adsorbed acrolein is decarbonyled into ethylene and carbon monoxide on a first reaction site. The formed carbon monoxide diffuses to another active site, where it reacts with water through the so called water-gas shift reaction to carbon dioxide and hydrogen. Said carbon dioxide leaves as an end-product, and the hydrogen diffuses to another active site where it reacts with ethylene to form ethane. This gives a way of producing energy gases from glycerol in a very compact reactor set-up, effectively reducing footprint and capital cost and increasing productivity of an installation.
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| 9. |
- Brandin, Jan, 1958-, et al.
(författare)
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Poisoning of SCR Catalysts used in Municipal Waste Incineration Applications
- 2017
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Ingår i: Topics in catalysis. - : Springer. - 1022-5528 .- 1572-9028. ; 60:17-18, s. 1306-1316
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Tidskriftsartikel (refereegranskat)abstract
- A commercial vanadia, tungsta on titania SCRcatalyst was poisoned in a side stream in a waste incinerationplant. The effect of especially alkali metal poisoning was observed resulting in a decreased activity at long times of exposure. The deactivation after 2311 h was 36% whilet he decrease in surface area was only 7.6%. Thus the major cause for deactivation was a chemical blocking of acidic sites by alkali metals. The activation–deactivation model showed excellent agreement with experimental data. The model suggests that the original adsorption sites, from the preparation of the catalyst, are rapidly deactivated but are replaced by a new population of adsorption sites due to activation of the catalyst surface by sulphur compounds (SO2, SO3) in the flue gas.
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| 10. |
- Brandin, Jan, 1958-
(författare)
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Preferential CO oxidation by mounted and un-mounted precious metal based catalyst
- 2005
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 30:11, s. 1235-1242
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Tidskriftsartikel (refereegranskat)abstract
- A number of different noble metal catalysts were studied for activity in the preferential oxidation of carbon monoxide in hydrogen-rich streams. The prepared catalysts had an active phase of platinum, palladium, iridium, ruthenium or rhodium impregnated either directly on an aluminia matrix or mounted on nickel or cobalt oxide. The catalysts were studied for activity, but also for the reversed water gas shift side reaction. The most active catalyst was platinum mounted on cobalt oxide and it was studied closely. The platinum on the cobalt oxide was studied using STEM with XEDS and the effects of the platinum cluster size were investigated. Via microscopy it was possible to show that platinum had no preference for either alumina or cobalt. The activity increased with increasing platinum cluster size but the selectivity passed through a maximum, a probable deactivation mechanism to the catalyst on stream, showed on a 1,000 h deactivated sample.
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| 11. |
- Brandin, Jan, 1958-
(författare)
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Reforming of tars and hydrocarbons from gasified biomass
- 2013
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Ingår i: Relesing Green Bioenergy for Human. - Dalia, PR China : BIT Congress.
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Konferensbidrag (refereegranskat)abstract
- Tars are produced during gasification of biomass due to thermal decomposition of main constituent of the biomass, cellulose, hemicellulose and lignin. Since the tars will condense on colder surfaces, they cause problems by clogging of pipes and valves and depositions on heat transfer surfaces, for instance. One strategy is to remove the tars by condensing them in water or oil scrubbers, however since the tars might contain a significant part of the heating value in the producer gas the yield of the produced synthesis gas will decrease. To utilize the heat content in the tars they can be converted in situ to synthesis gas either by a catalytic process like steam reforming or autothermal reforming (ATR). The problem with catalytic reforming is that the catalysts used are sensitive towards the sulphur content, mainly H2S, in the producer gas. The deactivation of the reforming catalysts can be counteracted by increasing the reforming temperature, for instance by the use of ATR. However, at elevated temperature, 1000-1100 oC, the thermal sintering of the catalyst will be accelerated instead. There is a need for development of new high temperature stable reforming catalysts. Another problem is the production of soot due to the high temperatures in the flame in the autothermal reformer unit. The formed sooth will cause problems by clogging packed bed of reforming catalyst and to cope with this it is probably necessary to use a monolithic catalyst. However, by developing a way to homogenous combust the added oxygen, avoiding the peak temperatures in the flame, would suppress or eventually eliminate the soot formation.
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| 12. |
- Brandin, Jan, 1958-, et al.
(författare)
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Selective Catalysts for Glycerol Dehydration
- 2013
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Ingår i: CRS-2, Catalysis for Renewable Sources. - Novosibirsk, Russia : Boreskov Institute of Catalysis. - 9785990255777 ; , s. 17-18
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Konferensbidrag (refereegranskat)abstract
- There has been an increased interest over the last decade for replacing fossil based feedstock’s with renewable ones. There are several such feedstock’s that are currently being investigated such as cellulose, lignin, hemicellulose, triglycerides etc. However, when trying to perform selective reactions an as homogeneous feedstock as possible is preferable. One such feedstock example is glycerol, a side-product from biofuels production, which is a tri-alcohol and thus has much flexibility for reactions, e.g. dehydration, hydrogenation, addition reactions etc. Glycerol in itself is a good starting point for fine chemicals production being non-toxic and available in rather large quantities [1-2]. A key reaction for glycerol valorisation is the dehydration of glycerol to form acrolein, an unsaturated C3 aldehyde, which may be used for producing acrylic acid, acrylonitrile and other important chemcial products. It has recently been shown that pore-condensation of glycerol is an issue under industrial like conditions, leading to liquid-phase reactions and speeding up the catalyst activity and selectivity loss [3]. To address this issue, modified catalyst materials have been prepared where the relevant micro and meso pores have been removed by thermal sintering; calculations have shown that pores below 45 Å may be subject to pore condensation. The catalyst starting material was a 10% WO3 by weight supported on ZrO2 in the form of beads 1–2 mm and it was thermally treated at 400°C, 500°C, 600°C, 700°C, 700°C, 800°C, 850°C, 900°C and 1000°C for 2 hours. The catalysts were characterised using nitrogen adsorption, mercury intrusion porosimetry (MIP), Raman spectroscopy and ammonia temperature programmed desorption. The thermal sintered catalysts show first of all a decreasing BET surface area with sintering commencing between 700°C and 800°C when it decreases from the initial 71 m2/g to 62 m2/g and at 1000°C there is a mere 5 m2/g of surface area left. During sintering, the micro and meso-porosity is reduced as evidenced by MIP and depicted in figure 1. As may be seen in the figure, sintering decrease the amount of pores below and around 100 Å is reduced at a sintering temperature of 800°C and above. The most suitable catalyst based on the MIP appears to be the one sintered at 850°C which is further strengthened by the Raman analysis. There is a clear shift in the tungsten structure from monoclinic to triclinic between 850°C and 900°C and it is believed that the monoclinic phase is important for activity and selectivity. Further, the heat treatment shows that there is an increase in catalyst acidity measured as mmol NH3/(m2/g) but a decrease in the acid strength as evidenced by a decrease in the desorption peak maximum temperature.
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| 13. |
- Brandin, Jan, 1958-, et al.
(författare)
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Small Scale Gasifiction : Gas Engine CHP for Biofuels
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In a joint project, Linnaeus University in Växjö (LNU) and the Faculty of Engineering at Lund University (LTH) were commissioned by the Swedish Energy Agency to make an inventory of the techniques and systems for small scale gasifier-gas engine combined heat and power (CHP) production and to evaluate the technology. Small scale is defined here as plants up to 10 MWth, and the fuel used in the gasifier is some kind of biofuel, usually woody biofuel in the form of chips, pellets, or sawdust. The study is presented in this report. The report has been compiled by searching the literature, participating in seminars, visiting plants, interviewing contact people, and following up contacts by e-mail and phone. The first, descriptive part of the report, examines the state-of-the-art technology for gasification, gas cleaning, and gas engines. The second part presents case studies of the selected plants: Meva Innovation’s VIPP-VORTEX CHP plant DTU’s VIKING CHP plant Güssing bio-power station Harboøre CHP plant Skive CHP plant The case studies examine the features of the plants and the included unit operations, the kinds of fuels used and the net electricity and overall efficiencies obtained. The investment and operating costs are presented when available as are figures on plant availability. In addition we survey the international situation, mainly covering developing countries. Generally, the technology is sufficiently mature for commercialization, though some unit operations, for example catalytic tar reforming, still needs further development. Further development and optimization will probably streamline the performance of the various plants so that their biofuel-to-electricity efficiency reaches 30-40 % and overall performance efficiency in the range of 90 %. The Harboøre, Skive, and Güssing plant types are considered appropriate for municipal CHP systems, while the Viking and VIPP-VORTEX plants are smaller and considered appropriate for replacing hot water plants in district heating network. The Danish Technical University (DTU) Biomass Gasification Group and Meva International have identified a potentially large market in the developing countries of Asia. Areas for suggested further research and development include: Gas cleaning/upgrading Utilization of produced heat System integration/optimization Small scale oxygen production Gas engine developments
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| 14. |
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| 15. |
- Brandin, Jan, 1958-, et al.
(författare)
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Unit operations for production of clean hydrogen-rich synthesis gas from gasified biomass
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 35:Supplement 1, s. S8-S15
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Tidskriftsartikel (refereegranskat)abstract
- The rebuild of the Växjö Värnamo Biomass Gasification Center (VVBGC) integrated gasification combined cycle (IGCC) plant into a plant for production of a clean hydrogen rich synthesis gas requires an extensive adaptation of conventional techniques to the special chemical and physical needs found in a gasified biomass environment. The CHRISGAS project has, in a multitude of areas, been responsible for the research and development activities associated with the rebuild. In this paper the present status and some of the issues concerning the upgrading of the product gas from gasified biomass into synthesis gas are addressed. The purpose is to serve as an introduction to the scientific papers written by the partners in the consortium concerning the unit operations of the process.
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| 16. |
- Brandin, Jan, 1958-
(författare)
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Usage of Biofuels in Sweden
- 2013
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Ingår i: CSR-2 Catalyst for renewable sources. - Novosibrisk, Russia : Boreskov Institute of Catalysis. - 9785990255777 ; , s. 5-7
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Konferensbidrag (refereegranskat)abstract
- In Sweden, biofuels have come into substantial use, in an extent that are claimed to be bigger than use of fossil oil. One driving force for this have been the CO2-tax that was introduced in 1991 (1). According to SVEBIO:s calculations (2) based on the Swedish Energy Agency´s prognosis, the total energy consumption in Sweden 2012 was 404 TWh. If the figure is broken down on the different energy sources (figure 1) one can see that the consumption roughly distribute in three different, equally sized, blocks, Biofuels, fossil fuels and water & nuclear power. The major use of the fossil fuels is for transport and the water & nuclear power is used as electric power. The main use of the biofuels is for heating in the industrial sector and as district heating. In 2009 the consumption from those two segments was 85 TWh, and 10 TWh of bio power was co-produced giving an average biomass to electricity efficiency of 12%. This indicates a substantial conversion potential from hot water production to combined heat and power (CHP) production. in Sweden 2013 broken down on the different energy sources. In 2006 the pulp, paper and sawmill industry accounted for 95% of the bio energy consumption in the industrial sector, and the major biofuel consumed was black liquor (5). However, the pulp and paper industries also produced the black liquor in their own processes. The major energy source (58%) for district heating during 2006 was woody biomass (chips, pellets etc.) followed by waste (24%), peat (6%) and others (12%) (5). The use of peat has probably decreased since 2006 since peat is no longer regarded as a renewable energy source. While the use of biofuel for heating purpose is well developed and the bio-power is expected to grow, the use in the transport sector is small, 9 TWh or 7% in 2011. The main consumption there is due to the mandatory addition (5%) of ethanol to gasoline and FAME to diesel (6). The Swedish authorities have announced plans to increase the renewable content to 7.5 % in 2015 on the way to fulfill the EU’s goal of 10 % renewable transportation fuels in 2020. However the new proposed fuel directive in EU says that a maximum of 5% renewable fuel may be produced from food sources like sugars and vegetable oils. Another bothersome fact is that, in principle, all rape seed oil produced in Sweden is consumed (95-97%) in the food sector, and consequently all FAME used (in principle) in Sweden is imported as FAME, rape seed oil or seed (6). In Sweden a new source of biodiesel have emerged, tall oil diesel. Tall oil is extracted from black liquor and refined into a diesel fraction (not FAME) and can be mixed into fossil diesel, i.e. Preem Evolution diesel. The SUNPINE plant in Piteå have a capacity of 100 000 metric tons of tall oil diesel per annum, while the total potential in all of Sweden is claimed to be 200 000 tons (7). 100 000 tons of tall oil corresponds to 1% of the total diesel consumption in Sweden. in Sweden for 2010 and a prognosis for 2014. (6). Accordingly, the profoundest task is to decrease the fossil fuel dependency in the transport sector, and clearly, the first generation biofuels can´t do this on its own. Biogas is a fuel gas with high methane content that can be used in a similar way to natural gas; for instance for cooking, heating and as transportation fuel. Today biogas is produced by fermentation of waste (municipal waste, sludge, manure), but can be produced by gasification of biomass, for instance from forest residues such as branches and rots (GROT in Swedish). To get high efficiency in the production, the lower hydrocarbons, mainly methane, in the producer gas, should not be converted into synthesis gas. Instead a synthesis gas with high methane content is sought. This limits the drainage of chemically bonded energy, due to the exothermic reaction in the synthesis step (so called methanisation). In 2011 0.7 TWh of biogas was produced in Sweden by fermentation of waste (6) and there were no production by gasification, at least not of economic importance. The potential seems to be large, though. In 2008 the total potential for biogas production, in Sweden, from waste by fermentation and gasification was estimated to 70 TWh (10 TWh fermentation and 60 TWh gasification) (8). This figure includes only different types of waste and no dedicated agricultural crops or dedicated forest harvest. Activities in the biogas sector, by gasification, in Sweden are the Göteborgs energi´s Gobigas project in Gothenburg and Eon´s Bio2G-project, now pending, in south of Sweden. If the producer gas is cleaned and upgraded into synthesis gas also other fuels could be produced. In Sweden methanol and DME productions are planned for in the Värmlands metanol-project and at Chemrecs DME production plant in Piteå.
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| 17. |
- Einvall, Jessica, et al.
(författare)
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High temperature water-gas shift step in the production of clean hydrogen rich synthesis gas from gasified biomass
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier. - 0961-9534 .- 1873-2909. ; 35:Supplement 1, s. S123-S131
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility of using the water-gas shift (WGS) step for tuning the H2/CO-ratio in synthesis gas produced from gasified biomass has been investigated in the CHRISGAS (Clean Hydrogen Rich Synthesis Gas) project. The synthesis gas produced will contain contaminants such as H2S, NH3 and chloride components. As the most promising candidate FeCr catalyst, prepared in the laboratory, was tested. One part of the work was conducted in a laboratory set up with simulated gases and another part in real gases in the 100 kW Circulating Fluidized Bed (CFB) gasifier at Delft University of Technology. Used catalysts from both tests have been characterized by XRD and N2 adsoption/desorption at −196 °C.In the first part of the laboratory investigation a laboratory set up was built. The main gas mixture consisted of CO, CO2, H2, H2O and N2 with the possibility to add gas or water-soluble contaminants, like H2S, NH3 and HCl, in low concentration (0–3 dm3 m−3). The set up can be operated up to 2 MPa pressure at 200–600 °C and run un-attendant for 100 h or more. For the second part of the work a catalytic probe was developed that allowed exposure of the catalyst by inserting the probe into the flowing gas from gasified biomass.The catalyst deactivates by two different causes. The initial deactivation is caused by the growth of the crystals in the active phase (magnetite) and the higher crystallinity the lower specific surface area. The second deactivation is caused by the presence of catalytic poisons in the gas, such as H2S, NH3 and chloride that block the active surface.The catalyst subjected to sulphur poisoning shows decreased but stable activity. The activity shows strong decrease for the ammonia and HCl poisoned catalysts. It seems important to investigate the levels of these compounds before putting a FeCr based shift step in industrial operation. The activity also decreased after the catalysts had been exposed to gas from gasified biomass. The exposed catalysts are not re-activated by time on stream in the laboratory set up, which indicates that the decrease in CO2-ratio must be attributed to irreversible poisoning from compounds present in the gas from the gasifier.It is most likely that the FeCr catalyst is suitable to be used in a high temperature shift step, for industrial production of synthesis gas from gasified biomass if sulphur is the only poison needed to be taken into account. The ammonia should be decomposed in the previous catalytic reformer step but the levels of volatile chloride in the gas at the shift step position are not known.
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| 18. |
- Gavrilovic, Ljubisa, et al.
(författare)
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Deactivation of Co-based Fischer-Tropsch catalyst by aerosol deposition of potassium salts
- 2018
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Ingår i: Industrial & Engineering Chemistry Research. - Washington, USA : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 57:6, s. 1935-1942
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Tidskriftsartikel (refereegranskat)abstract
- A 20%Co/0.5%Re/γAl2O3 Fischer-Tropsch catalyst was poisoned by four potassium salts (KNO3, K2SO4, KCl, K2CO3) using the aerosol deposition technique, depositing up to 3500 ppm K as solid particles. Standard characterization techniques (H2 Chemisorption, BET, TPR) showed no difference between treated samples and their unpoisoned counterpart. The Fischer-Tropsch activity was investigated at industrially relevant conditions (210 °C, H2:CO = 2:1, 20 bar). The catalytic activity was significantly reduced for samples exposed to potassium, and the loss of activity was more severe with higher potassium loadings, regardless of the potassium salt used. A possible dual deactivation effect by potassium and the counter-ion (chloride, sulfate) is observed with the samples poisoned by KCl and K2SO4. The selectivity towards heavier hydrocarbons (C5+) was slightly increased with increasing potassium loading, while the CH4 selectivity was reduced for all the treated samples. The results support the idea that potassium is mobile under FT conditions. The loss of activity was described by simple deactivation models which imply a strong non-selective poisoning by the potassium species.
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| 19. |
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| 20. |
- Gavrilovic, Ljubisa, et al.
(författare)
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Fischer-Tropsch synthesis : Investigation of the deactivation of a Co catalyst by exposure to aerosol particles of potassium salt
- 2018
-
Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 230, s. 203-209
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of potassium species on a Co based Fischer-Tropsch catalyst was investigated using an aerosol deposition technique. This way of poisoning the catalyst was chosen to simulate the actual potassium behaviour during the biomass to liquid (BTL) process utilizing gasification followed by fuel synthesis. A reference catalyst was poisoned with three levels of potassium and the samples were characterized and tested for the Fischer-Tropsch reaction under industrially relevant conditions. None of the conventional characterization techniques applied (H2 Chemisorption, BET, TPR) divulged any difference between poisoned and unpoisoned samples, whereas the activity measurements showed a dramatic drop in activity following potassium deposition. The results are compared to previous results where incipient wetness impregnation was used as the method of potassium deposition. The effect of potassium is quite similar in the two cases, indicating that irrespective of how potassium is introduced it will end up in the same form and on the same location on the active surface. This indicates that potassium is mobile under FTS conditions, and that potassium species are able to migrate to sites of particular relevance for the FT reaction.
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| 21. |
- Gavrilovic, Ljubisa, et al.
(författare)
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Influence of potassium species on Co based Fischer-Tropsch-catalyst.
- 2016
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Konferensbidrag (refereegranskat)abstract
- 1. IntroductionThe purpose of this work is better understanding of the alkali influence on Co-based F-T catalyst. Since potassium is one of the elements that can be present in syngas from biomass[1], one of the questions is how potassium species affect the Co catalyst. From previous work it has been shown that alkali species act as poisons, thus deactivating catalysts[2]. Most previous work in this group[3][4] and by others[5] has concerned Co catalysts that were exposed to potassium species by incipient wetness impregnation, which is essentially different from the real behaviour during the gasification process where the species will mainly be in the vapor phase. In the present work we study potassium influence on a Co-based catalyst, using aerosol technology as a new method for potassium deposition on the Co surface. 2. Experimental4 different potassium salts were deposited using aerosol deposition on 20%Co/0.5%Re/γAl2O3. The amount of potassium salts deposited were determined using ICP analysis. Potassium salts were chosen from studies of the gases from biomass gasification[6]. These are K2SO4, KCl, KNO3 and K2CO3. KNO3 will be reduced to KOH during biomass gasification, but since in these experiments temperature was not so high and there was no H2/CO, most likely KNO3 will be deposited as such on the Co surface.BET N2 adsorption, H2 chemisorption, temperature programmed reduction (TPR) were used to characterize all the poisoned catalysts.Fischer Tropsch activity and selectivity measurements were performed at the in house build set-up, at 210°C, 20 bar and at H2:CO ratio of 2.1. The GHSV was consistently varied to maintain comparable CO conversion levels between 20-50%. A detailed description of the setup and procedures can be found elsewhere[3]. 3. ResultsThe potassium species were deposited using aerosol technology in the apparatus shown in Fig. 1. Potassium salts are dissolved in deionized water and the solution is placed inside the atomizer, which produces aerosol particles. Nitrogen is used as a carrier gas which forces aerosol particles in the reactor direction. Before entering the reactor, the gas mixture carrying the aerosol is passing the impaction vessel to remove large particles. The catalyst bed is placed in the middle of the reactor, which can be heated up to 800°C. The generated aerosol particles were physically characterized according to their electrical mobility using a scanning mobility particle sizer (SMPS) consisting of a differential mobility analyser (DMA) and a condensation particle counter (CPC)[7]. The three target concentrations of potassium salts, 200 ppm, 800 ppm and 4000 ppm, were monitored by the above-mentioned instruments.Results from characterization by elemental analysis, H2 chemisorption, BET surface area, TPR together with the results from the Fischer Tropsch synthesis i.e. CO conversion, selectivity, and activity will be compared with the same catalyst without any poison and also with previous results obtained from solution impregnation of the same poisons[8][3][9].4. DiscussionThe purpose of the work is to study how this procedure of poisoning Co catalyst with aerosol particles will affect catalyst performances during Fischer Tropsch reaction. Previous similar work on Ni catalyst in the SCR reaction using aerosol technology as a method of deposition, has proven loss in metallic surface area, decreasing of metal dispersion and severe reduction in the catalytic activity [7]. The idea is to develop a technique to transfer potassium species, and potentially other relevant impurities, in vapor phase to the catalyst surface. This new approach can to a great extent simulate behaviour during the real industrial process. The aerosol could better represent in situ poisoning and therefore give a more realistic picture of the effect of potassium. This knowledge will be useful for designing new BTL processes. 5. ConclusionAerosol technology was used as a new method for depositing potassium salts on the Co surface. Poisoned catalysts were tested in Fischer Tropsch synthesis reactor together with elemental analysis. Results are compared to the reference catalyst and with previous work which use IWI as poisoning method. 6. References[1] A. Norheim, D. Lindberg, J. E. Hustad, and R. Backman, Energy and Fuels, (2009)[2] E. S. Wangen, A. Osatiashtiani, and E. A. Blekkan, Top. Catal., (2011)[3] C. M. Balonek, A. H. Lillebø, S. Rane, E. Rytter, L. D. Schmidt, and A. Holmen, Catal. Letters, (2010)[4] E. A. Blekkan, A. Holmen, S. Vada, Acta Chem. Scand., (1993)[5] J. Gaube and H. F. Klein, Appl. Catal. A Gen., (126–132, 2008)[6] H. M. Westberg, M. Byström, and B. Leckner, Energy and Fuels, (18–28, 2003)[7] S. Albertazzi, F. Basile, J. Brandin, J. Einvall, G. Fornasari, C. Hulteberg, M. Sanati, F. Trifirò, and A. Vaccari, Biomass and Bioenergy, (2008)[8] A. H. Lillebø, E. Patanou, J. Yang, E. A. Blekkan, and A. Holmen, in Catalysis Today, (2013)[9] E. Patanou, A. H. Lillebø, J. Yang, D. Chen, A. Holmen, and E. A. Blekkan, Ind. Eng. Chem. Res., (2014)[10] J. Einvall, S. Albertazzi, C. Hulteberg, A. Malik, F. Basile, A. C. Larsson, J. Brandin, and M. Sanati, Energy and Fuels, (2007)
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| 22. |
- Gavrilovic, Lubisa, et al.
(författare)
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The effect of aerosol-deposited ash components on a cobalt-based Fischer–Tropsch catalyst
- 2019
-
Ingår i: Reaction Kinetics, Mechanisms and Catalysis. - : Springer. - 1878-5190 .- 1878-5204. ; 127:1, s. 231-240
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of ash salts on Co-based Fisher–Tropsch catalysts was studied using an aerosol deposition technique. The major elements in the ash were found to be K, S and Cl. The ash was deposited on a calcined catalyst as dry particles with an average diameter of approx. 350 nm. The loading of ash particles was varied by varying the time of exposure to the particles in a gas stream. Catalyst characterization did not reveal significant differences in cobalt dispersion, reducibility, surface area, pore size, or pore volume between the reference and the catalysts with ash particles deposited. Activity measurements showed that following a short exposure to the mixed ash salts (30 min), there were no significant loss of activity, but a minor change in selectivity of the catalyst . Extended exposure (60 min) led to some activity loss and changes in selectivity. However, extending the exposure time and thus the amount deposited as evidenced by elemental analysis did not lead to a further drop in activity. This behavior is different from that observed with pure potassium salts, and is suggested to be related to the larger size of the aerosol particles deposited. The large aerosol particles used here were probably not penetrating the catalyst bed, and to some extent formed an external layer on the catalyst bed. The ash salts are therefore not able to penetrate to the pore structure and reach the Co active centers, but are mixed with the catalyst and detected in the elemental analysis.
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| 23. |
- Hulteberg, Christian, et al.
(författare)
-
A Process for Producing Acrolein
- 2012
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Patent (populärvet., debatt m.m.)abstract
- Disclosed is a process for dehydrating glycerol into acrolein over an acidic catalyst in gas phase in the presence of hydrogen, minimizing side reactions forming carbon deposits on the catalyst.
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| 24. |
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| 25. |
- Hulteberg, Christian, et al.
(författare)
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Method for Hydrogenating 1,2-Unsaturated Carbonylic Compounds
- 2011
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Patent (populärvet., debatt m.m.)abstract
- Disclosed is a method of hydrogenating an1,2-unsaturated carbonylic compound to obtain the corresponding saturated carbonylic compound in the presence of a palladium catalyst with heterogeneous distribution of palladium
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| 26. |
- Hulteberg, Christian, et al.
(författare)
-
Pore Condensation i Glycerol Dehydration
- 2013
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Ingår i: Topics in catalysis. - : Springer. - 1022-5528 .- 1572-9028. ; 56:9-10, s. 813-821
-
Tidskriftsartikel (refereegranskat)abstract
- Pore condensation followed by polymerizationis proposed as an explanatory model of several observationsreported in the literature regarding the dehydration ofglycerol to acrolein. The major conclusion is that glycerolpore condensation in the micro- and mesopores, followedby polymerization in the pores, play a role in catalystdeactivation.
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| 27. |
- Hulteberg, Christian, et al.
(författare)
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Pore Condensation in Glycerol Dehydration : Modification of a Mixed Oxide Catalyst
- 2017
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Ingår i: Topics in catalysis. - : Springer. - 1022-5528 .- 1572-9028. ; 60:17-18, s. 1462-1472
-
Tidskriftsartikel (refereegranskat)abstract
- Pore condensation has been suggested as an initiator of deactivation in the dehydration of glycerol to acrolein. To avoid potential pore condensation of the glycerol, a series of WO3supported on ZrO2 catalysts have been prepared through thermal sintering, with modified pore systems. It was shown that catalysts heat treated at temperatures above 800 °C yielded suitable pore system and the catalyst also showed a substantial increase in acrolein yield. The longevity of the heat-treated catalysts was also improved, indeed a catalyst heat treated at 850 °C displayed significantly higher yields and lower pressure-drop build up over the 600 h of testing. Further, the catalyst characterisation work gave evidence for a transition from monoclinic to triclinic tungsten oxide between 850 and 900 °C. There is also an increase in acid-site concentration of the heat-treated catalysts. Given the improved catalyst performance after heat-treatment, it is not unlikely that pore condensation is a significant contributing factor in catalyst deactivation for WO3 supported on ZrO2 catalysts in the glycerol dehydration reaction.
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- Kirm, Ilham, et al.
(författare)
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Shift catalysts in biomass generated synthesis gas
- 2007
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Ingår i: Topics in catalysis. - : Springer verlag. - 1022-5528 .- 1572-9028. ; 45:1-4, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- One of the CHRISGAS project objectives is to study the shift catalysts in biomass-generated synthesis gas. The water gas shift reaction is ruled by equilibrium, and the state of the gas can for a given H2/CO ratio be shifted by addition/removal of water, CO2 and/or by a change in the temperature. Stability area in respect to gas composition, sulphur content, pressure and temperature for FeCr shift catalyst has been investigated by thermodynamic equilibrium calculations. The calculations show that carbide formation is favourable in the “Normal water” case without sulphur in the gas. If sulphur is present in the gas, the situation improves due to sulphide formation.
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| 32. |
- Meessen, Jo, et al.
(författare)
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Process for the reduction of ammonia emissions in a urea manufacturing process
- 2011
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Patent (populärvet., debatt m.m.)abstract
- The present invention relates to a process for removing ammonia from an effluent of an ammonia enriched gaseous stream formed in or downstream the finishing section of a urea manufacturing process, said ammonia enriched gaseous stream comprising 200 mg NH 3 /Nm 3 or less, wherein the ammonia enriched gaseous stream is contacted with an aqueous composition comprising phosphoric acid thereby producing an ammonia enriched liquid effluent, wherein a bleed of the ammonia enriched liquid effluent is subjected to a urea decomposition step. The present invention also relates to a process for producing an ammonium phosphate essentially free of contaminants, said process comprising the following steps: (a) contacting an ammonia enriched gaseous stream comprising 200 mg NH 3 /Nm 3 or less with an aqueous composition comprising phosphoric acid thereby producing an ammonia enriched liquid effluent; and (b) subjecting a bleed of the ammonia enriched liquid effluent to a urea decomposition step.
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| 33. |
- Nørregård, Øyvind, et al.
(författare)
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Catalyst choise and considerations in the conversion of Glucose to glycerol.
- 2016
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Ingår i: Proceedings of the 17th Nordic Symposium on Catalysis. ; , s. 204-206
-
Konferensbidrag (refereegranskat)abstract
- Through the 20th century the use of glycerine has mainly been focused to the food industry, the cosmetic industry and the pharmaceutical industry. The required volumes for these industries can’t be compared with the larger bulk chemicals produced today. These low requirements together with the increased glycerine production, associated with the biodiesel production from which glycerine is a large by-product, has forced the prices down to approximately 100-150 $/tonne. This low cost crude glycerine has been an initiator for developing methods on how to convert the glycerine to more usable products. A proposed method by the company Biofuel Solutions has been to convert the glycerine into bio-LPG. With the EU directives stating that at least 10 % of the fuels in the transport sector should come from renewable sources this route may turn out favourable. This will though cause a large increase in demand as one of the few new ways to provide bio-LPG and thus increase in price, which will require new ways to produce glycerine.With a possible increased demand on glycerine a proposed route to produce glycerine is via catalytic hydrogenation of glucose to sorbitol and further catalytic hydrogenolysis of sorbitol to glycerine. The production of sorbitol from glucose is today already industrialised with large producers such as Roquette Frères, Cargill and SPI Polyols. The industrial process is historically made batch wise with low cost Raney-nickel catalyst but with the development of good selectivity catalysts with no leaching problems it is assumed that todays’ production is mainly operating with catalyst with noble metals as the active metal, such as ruthenium, in a continuous process. For the hydrogenolysis of sorbitol to glycerine a good method is rather unexplored as the hydrogenolysis is previously mostly performed with either ethylene glycol (EG) or propylene glycol (PG) as the wanted product [1]. In context with the text above it is of great interest to investigate the catalytic hydrogenolysis of sorbitol to glycerine for the further production of bio-LPG.Research made on catalytic hydrogenolysis of sorbitol is done with mostly glycols as the main products, [1]. With the still reasonable selectivity of glycerine, up to 40 % with Raney-nickel as catalyst [2], the proposed research method is similar [1-3]. The planned method performed by Biofuel-Solutions includes trials in an autoclave reactor with the catalyst dispersed in the reactant solution under hydrogen pressure of 20-100 bar and mild temperatures, 100-300 °C, and stirring in resemblance to previous research [4]. As leaching issues has been seen with Raney-nickel in the hydrogenation of glucose to produce sorbitol [5], a similar process, this behaviour is expected to require certain measures which also will be tested. Tests will also include to investigate the influence of the catalyst basicity, which seems to affect the selectivity towards glycerol positively [1,2,5].A final process of producing bio-LPG with the start from glucose is seen in Figure 1 below. In the picture a long chain of processes-steps is displayed. In the blue box the degradation of the lignocellulosic material takes place. This is then led to the fraction where glucose is required from enzymatic hydrolysis. In the grey box to the right the glycerol conversion to LPG is shown, a multi process-step of which most details are already known within the company.
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| 34. |
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| 35. |
- Parsland, Charlotte, et al.
(författare)
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Ba-Ni-Hexaaluminate as a New Catalyst in the Steam Reforming of 1-Methyl Naphthalene and Methane Long-Term Studies on Sulphur Deactivation and Coke Formation
- 2020
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Ingår i: Catalysis Letters. - : Springer. - 1011-372X .- 1572-879X. ; 150, s. 1605-1617
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigates the long-term performance of Ba-Ni-hexaaluminate, BaNixAl12-xO19 as a catalyst in reforming of 1-methyl naphthalene and/or methane in a model-gas simulating that from a circulating fluidized bed (CFB) gasifier during 23-29 h in a lab scale set-up, as well as the tendency for coke formation, sintering and sulphur poisoning. 1-Methyl naphthalene is used as a tar model substance. The Ba-Ni-hexaaluminate induces a high conversion of both compounds in the temperatures investigated (850 and 950 degrees C) under sulphur-free conditions. In sulphur-containing gas, the methane conversion stops at 20 ppm H2S and the reforming of 1-MNP at 850 degrees C is slightly reduced at 100 ppm.
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| 36. |
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| 37. |
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| 38. |
- Parsland, Charlotte, et al.
(författare)
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Nickel-substituted Ba-hexaaluminates as catalysts stem-reforming of tars
- 2013
-
Ingår i: CRS-2, Catalysis for Renewable sources. - Novosibirsk : Boreskov Institute of Catalysis. - 9785990255777 ; , s. 62-63
-
Konferensbidrag (refereegranskat)abstract
- Gasification of woody biomass converts the solid organic material into a gaseous product with a higher energy value and by this mean provide a more carbon neutral gaseous fuel than the common fossil ones. The produced raw gas mainly contains H2, CO, CO2, CH4, H2O and N2 together with organic (tars) and inorganic (alkali) components and fine particulates. The amount of impurities in the raw gas is dependent of the fuel properties and the gasification process technology and the quality of the resulting product gas determines its suitability for more advanced purposes. One of the major general concerns within the gasification processes is the formation of tars. Tars are a vast group of polyaromatic hydrocarbons and there are a number of definitions. On an EU/IEA/US-DOE discussion meeting in Brussels 1998, a number of experts agreed on a simplified classification of tars as “all organic contaminants with a molecular weight larger than benzene” [1]. The aim of this work is to investigate the steam reforming ability of a catalytic material not previously tested in this type of application in order to achieve an energy-efficient and high-quality gasification gas. The physical demands for an optimal tar-cracking and steam reforming catalyst is a high surface area, thermal stability, mechanical strength and a capacity to withstand high gas velocities, poisons such as H2S or NH3 and other impurities. Additionally it has to resist the process steam, as steam is well known to enhance sintering of porous materials. Nickel is a familiar catalyst for steam reforming. Hexaaluminate is a well-known catalyst support with properties that may answer to the requests of a non-abrasive, high-temperaturestable and steam-resistant catalytic material. It is a structural oxide where the general formula for the doped unit cell is MIMII(x)Al12-xO19-d where MI represents the mirror plane cation and MII is the aluminum site in the lattice where substitution may occur. MII is often a transition metal ion of the same size and charge as aluminum. MI is an ion located in the mirror plane of the structure and it is a large metal ion, often from the alkaline, alkaline earth or rare earth metal group. The stability and activity of these materials are often being related to the properties of MI and MII. The activity is highly dependent on the nature of the Al-substituted metal and partially by the nature of MII [2]. In our experiments we have tested the catalytic capacity of Ni-substituted Ba-hexaaluminates synthesised by the sol-gel method [3], both in a model set-up and in a gasification plant. In the lab-scale set-up different catalyst-formulae was tested under various temperatures for reforming of methyl-naphthalene. The results show a good catalytic activity for tar-breakdown. As expected the substitution level of Ni is clearly coupled to the reaction temperature. With the most highly substituted Ni-Bahexaaluminate at 900 °C all of the methyl-naphthalene has been broken downtogether with all of the resulting hydrocarbons. The Ni-Bahexaaluminate catalyst has recently also been tested in real process-gas.These results are still to be evaluated, but indicate a positive result.
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| 39. |
- Parsland, Charlotte, et al.
(författare)
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Nickel-substituted bariumhexaaluminates as novel catalysts in steam reforming of tars
- 2015
-
Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 140, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the performance of Ba–Ni-hexaaluminate, BaNixAl12 − xO19, as a new catalyst in thesteam-reforming of tars. Substituted hexaaluminates are synthesized and characterized. Steam reforming testsare carried out with both a model-substance (1-methylnaphthalene) and a slip-stream from a circulatingfluidized bed gasifier. The water–gas-shift activity is studied in a lab-scale set-up. Barium–nickel substitutedhexaaluminates show a high catalytic activity for tar cracking, and also shows activity for water–gas-shift.
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| 40. |
- Svensson, Helena, et al.
(författare)
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Modeling of soot formation during partial oxidation of producer gas
- 2013
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 106, s. 271-278
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Tidskriftsartikel (refereegranskat)abstract
- Soot formation in a reverse-flow partial-oxidation reactor for reforming of gasifier producer gas has been studied. The process was modeled using a detailed reaction mechanism to describe the kinetics of soot formation. The numerical model was validated against experimental data from the literature and showed good agreement with reported data. Nine cases with different gas compositions were simulated in order to study the effects of water, hydrogen and methane content of the gas. The CO and CO2 contents, as well as the tar content of the gas, were also varied to study their effects on soot formation. The results showed that the steam and hydrogen content of the inlet gas had less impact on the soot formation than expected, while the methane content greatly influenced the soot formation. Increasing the CO2 content of the gas reduced the amount of soot formed and gave a higher energy efficiency and methane conversion. In the case of no tar in the incoming gas the soot formation was significantly reduced. It can be concluded that removing the tar in an energy efficient way, prior to the partial oxidation reactor, will greatly reduce the amount of soot formed. Further investigation of tar reduction is needed and experimental research into this process is ongoing.
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| 41. |
- Svensson, Helena, et al.
(författare)
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Soot formation in reverse flow reforming of biomass gasification producer gas
- 2010
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Ingår i: Proceedings of 18th European biomass conference and exhibition. Lyon, France. - : ETA Renewable Energies and WIP Renewable Energies. - 8889407565 ; DVD, s. 766-770
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Konferensbidrag (refereegranskat)abstract
- The aim of this work was to determine the extent to which soot is formed and if there are any ways of reducing the formation of soot. In order to determine if soot formation will be a critical issue for the reverse flow reforming process modeling of the process was undertaken. The reformer was modeled using a detailed reaction mechanism to describe the kinetics of soot formation.The results of the simulations show that soot will be formed under the modeled conditions. Almost 10 % of the ingoing carbon will be converted to soot. It is worth noting that the tars present in the gasification producer gas account for more than 5 % of the ingoing carbon. The soot formation can be reduced with more than 20 % by using a simple thermal pre-reformer where higher hydrocarbons (C2 and higher) and some of the tars are reformed. By using a low temperature reverse flow reformer as a pre-reformer the soot formation can be reduced by nearly 30 % making it a highly effective alternative. A catalytic pre-reformer will most likely produce better results because of the lower temperature needed for reforming the higher hydrocarbons as compared to methane.
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| 42. |
- Tunå, Per, et al.
(författare)
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Modeling of Reverse Flow Partial Oxidation Process for Gasifier Product Gas Upgrading
- 2010
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Ingår i: Proceedings of the 5th International Conference on Thermal Engineering:Theory and Applications 2010. - 1894503937
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Konferensbidrag (refereegranskat)abstract
- Biomass gasification is one of the alternatives to producing liquid fuels and chemicals from biomass residues. The gas produced in gasification contains CO, H2, H2O, CO2, light hydrocarbons and tars. Depending on the gasifier type, operating conditions and fuel, the light hydrocarbons can contain as much as 50 % of the total energy contents in the gas. The gas also contains catalyst poisons such as sulfur, as H2S and COS. This paper presents simulation work of a reverse flow partial oxidation reformer that reaches efficiencies approaching conventional catalytical processes. Furthermore, different reactor designs and parameter variations such as pressure are investigated. For comparison, natural gas simulations are included which clearly show the benefits of using reverse flow operation with lean gases such as gasifier product gas.
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| 43. |
- Tunå, Per, et al.
(författare)
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Modelling of a reverse-flow partial oxidation reactor for synthesis gas production from gasifier product gas.
- 2015
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Ingår i: Journal of Computational Methods in Sciences and Engineering. - : IOS Press. - 1472-7978 .- 1875-8983. ; 15:3, s. 593-604
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Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification followed by fuel synthesis is one of the alternatives for producing liquid fuels and chemicalsfrom biomass feedstocks. The gas produced by gasification contains CO, H2, H2O, CO2, light hydrocarbons and tars. Thelight hydrocarbons can account for as much as 50% of the total energy content of the gas, depending on the type of gasifier,operating conditions and feedstock. The gas also contains catalyst poisons such as sulphur, in the form of H2S and COS. Thispaper presents simulations of a reverse-flow partial-oxidation reformer that converts the light hydrocarbons into more synthesisgas, while achieving efficiencies approaching that of conventional catalytic processes. Variations in parameters such as pressure,amount of oxidant and steam-to-carbon ratio were also investigated. Simulations of the reforming of natural gas were includedfor comparison. The results show the benefits of using reverse-flow operation with lean gases such as gasifier product gas.
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