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Öhrman, Olov
Alternative names
Publications (10 of 31) Show all publications
Grahn, M., Faisal, A., Öhrman, O. G. ., Zhou, M., Signorile, M., Crocellà, V., . . . Hedlund, J. (2019). Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons. Catalysis Today
Open this publication in new window or tab >>Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons
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2019 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308Article in journal (Refereed) Epub ahead of print
Abstract [en]

This work presents the synthesis of nearly defect-free ZSM-5 nanosized crystals, prepared in fluoride medium by seeding with silicalite-1. This material was carefully characterized and its catalytic performances in the methanol to hydrocarbons (MTH) reaction were assessed. Such fluoride-based material was compared to a reference ZSM-5, produced through a conventional alkaline synthesis but from the same seeding. Despite both the materials show closely identical morphology and they have a comparable acid site population, the catalyst prepared using the fluoride route showed significantly longer lifetime in MTH compared to the catalyst prepared using conventional synthesis at high pH. The slower deactivation for the samples prepared using the fluoride route was ascribed, thanks to a thorough in situ IR spectroscopy study, to its lower density of internal defects. According to the UV-Raman characterization of coke on the spent catalyst, the fluoride-based ZSM-5 catalyst produces less molecular coke species, most probably because of the absence of enlarged cavities/channels as due to the presence of internal defects. On the basis of these observations, the deactivation mechanism in the ZSM-5 synthesized by fluoride medium could be mostly related to the deposition of an external layer of bulk coke, whereas in the alkali-synthesized catalyst an additional effect from molecular coke accumulating within the porous network accelerates the deactivation process.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
ZSM-5, defects, hydrocarbons, deactivation, MTH, IR spectroscopy, OH groups
National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-76102 (URN)10.1016/j.cattod.2019.09.023 (DOI)2-s2.0-85073006485 (Scopus ID)
Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-11-26
Johansson, A.-C., Sandström, L., Öhrman, O. & Jilvero, H. (2018). Co-pyrolysis of woody biomass and plastic waste in both analytical and pilot scale. Journal of Analytical and Applied Pyrolysis, 134, 102-113
Open this publication in new window or tab >>Co-pyrolysis of woody biomass and plastic waste in both analytical and pilot scale
2018 (English)In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 134, p. 102-113Article in journal (Refereed) Published
Abstract [en]

Earlier studies show that co-pyrolysis of biomass and plastics can improve the quantity and quality of the produced pyrolysis oil compared to pyrolysis of the separate feedstocks. In this work three relevant plastic wastes; paper reject, shredder light fraction and cable plastics; were evaluated together with woody biomass (stem wood from spruce and pine) using analytical pyrolysis, Py-GC-MS/FID. One verification experiment was also conducted in a cyclone pyrolyser pilot plant at industrially relevant conditions.

The addition of plastic waste to woody biomass pyrolysis was found to significantly affect the composition and properties of the produced pyrolysis products. In analytical pyrolysis experiments, positive synergetic effects were observed in the co-pyrolysis of paper reject and cable plastics together with the stem wood. The yield of reactive oxygenated compounds (ketones, aldehydes and acids) was suppressed while more stable alcohols and esters were promoted. The formation of hydrocarbons was also promoted in the co-pyrolysis of plastics from paper reject and stem wood. The results from the analytical pyrolysis were partly verified in the pilot scale experiment by co-pyrolysing stem wood and paper reject. However, the co-pyrolysis also affected other parameters that cannot be detected in analytical pyrolysis such as higher acidity and viscosity of the oil which highlights the need for undertaking experiments at different scales. The product yields in pilot scale were about the same for the co-pyrolysis case as for pure stem wood. However, a high volatile content of the solid product indicated that the process conditions can be further optimized for co-pyrolysing cases.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Chemical Engineering Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-69111 (URN)10.1016/j.jaap.2018.05.015 (DOI)000445306600011 ()2-s2.0-85048546574 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-03 (andbra)

Available from: 2018-06-05 Created: 2018-06-05 Last updated: 2019-01-18Bibliographically approved
Wiinikka, H., Weiland, F., Pettersson, E., Öhrman, O., Carlsson, P. & Stjernberg, J. (2014). Characterisation of submicron particles produced during oxygen blown entrained flow gasification of biomass (ed.). Paper presented at . Combustion and Flame, 161(7), 1923-1934
Open this publication in new window or tab >>Characterisation of submicron particles produced during oxygen blown entrained flow gasification of biomass
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2014 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 161, no 7, p. 1923-1934Article in journal (Refereed) Published
Abstract [en]

In this paper submicron particles sampled after the quench during 200 kW, 2 bar(a) pressurised, oxygen blown gasification of three biomass fuels, pure stem wood of pine and spruce, bark from spruce and a bark mixture, have been characterised with respect to particle size distribution with a low pressure cascade impactor. The particles were also characterised for morphology and elemental composition by a combination of scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and high resolution transmission electron microscopy/energy dispersive spectroscopy/selected area electron diffraction pattern (HRTEM/EDS/SAED) techniques. The resulting particle concentration in the syngas after the quench varied between 46 and 289 mg/Nm3 consisting of both carbon and easily volatile ash forming element significantly depending on the fuel ash content. Several different types of particles could be identified from classic soot particles to pure metallic zinc particles depending on the individual particle relation of carbon and ash forming elements. The results also indicate that ash forming elements and especially zinc interacts in the soot formation process creating a particle with shape and microstructure significantly different from a classical soot particle.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-3447 (URN)10.1016/j.combustflame.2014.01.004 (DOI)000337200700020 ()2-s2.0-84901625416 (Scopus ID)1451860f-0982-463f-b03f-8e4cfea8dd3b (Local ID)1451860f-0982-463f-b03f-8e4cfea8dd3b (Archive number)1451860f-0982-463f-b03f-8e4cfea8dd3b (OAI)
Note
Validerad; 2014; 20140128 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Risberg, M., Öhrman, O., Gebart, R., Nilsson, P., Gudmundsson, A. & Sanati, M. (2014). Influence from fuel type on the performance of an air-blown cyclone gasifier (ed.). Paper presented at . Fuel, 116, 751-759
Open this publication in new window or tab >>Influence from fuel type on the performance of an air-blown cyclone gasifier
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2014 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 116, p. 751-759Article in journal (Refereed) Published
Abstract [en]

Entrained flow gasification of biomass using the cyclone principle has been proposed in combination with a gas engine as a method for combined heat and power production in small to medium scale (<20 MW). This type of gasifier also has the potential to operate using ash rich fuels since the reactor temperature is lower than the ash melting temperature and the ash can be separated after being collected at the bottom of the cyclone. The purpose of this work was to assess the fuel flexibility of cyclone gasification by performing tests with five different types of fuels; torrefied spruce, peat, rice husk, bark and wood. All of the fuels were dried to below 15% moisture content and milled to a powder with a maximum particle size of around 1 mm. The experiments were carried out in a 500 kWth pilot gasifier with a 3-step gas cleaning process consisting of a multi-cyclone for removal of coarse particles, a bio-scrubber for tar removal and a wet electrostatic precipitator for removal of fine particles and droplets from the oil scrubber (aerosols). The lower heating value (LHV) of the clean producer gas was 4.09, 4.54, 4.84 and 4.57 MJ/N m3 for peat, rice husk, bark and wood, respectively, at a fuel load of 400 kW and an equivalence ratio of 0.27. Torrefied fuel was gasified at an equivalence ratio of 0.2 which resulted in a LHV of 5.75 MJ/N m3 which can be compared to 5.50 MJ/N m3 for wood powder that was gasified at the same equivalence ratio. A particle sampling system was designed in order to collect ultrafine particles upstream and downstream the gasifier cleaning device. The results revealed that the gas cleaning successfully removed >99.9% of the particulate matter smaller than 1 μm.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-4473 (URN)10.1016/j.fuel.2013.08.008 (DOI)000326943400095 ()2-s2.0-84884801889 (Scopus ID)2691e4a6-1b23-4e4b-a666-227791bb12fb (Local ID)2691e4a6-1b23-4e4b-a666-227791bb12fb (Archive number)2691e4a6-1b23-4e4b-a666-227791bb12fb (OAI)
Note
Validerad; 2014; 20130809 (mikris)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Landälv, I., Gebart, R., Marke, B., Granberg, F., Furusjö, E., Löwnertz, P., . . . Salomonsson, P. (2014). Two years experience of the BioDME project: A complete wood to wheel concept (ed.). Paper presented at International Conference on Thermochemical Conversion of Biomass : 03/09/2013 - 06/09/2013. Environmental Progress & Sustainable Energy, 33(3), 744-750
Open this publication in new window or tab >>Two years experience of the BioDME project: A complete wood to wheel concept
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2014 (English)In: Environmental Progress & Sustainable Energy, ISSN 1944-7442, E-ISSN 1944-7450, Vol. 33, no 3, p. 744-750Article in journal (Refereed) Published
Abstract [en]

Dimethyl ether (DME), is an excellent diesel fuel that can be produced through gasification from multiple feedstocks. One particularly interesting renewable feedstock is the energy rich by-product from the pulping process called black liquor (BL). The concept of utilizing BL as gasifier feed, converting it via syngas to DME and then compensating the withdrawal of BL energy from the pulp mill by supplying biomass to a conventional combined heat and power plant, is estimated to be one of the most efficient conversion concepts of biomass to a renewable fuel on a well-to-wheel basis. This concept has been demonstrated by the four-year BioDME project, including field tests of DME-fueled heavy-duty trucks that are operated commercially. Up till the summer of 2013 more than 500 tons of BioDME has been produced and distributed to 10 HD trucks, which in total has run more than 1 million km in commercial service

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-30055 (URN)10.1002/ep.11993 (DOI)000339545100013 ()2-s2.0-84904251993 (Scopus ID)3be53abf-6fb1-4059-9cd9-1484894a4a16 (Local ID)3be53abf-6fb1-4059-9cd9-1484894a4a16 (Archive number)3be53abf-6fb1-4059-9cd9-1484894a4a16 (OAI)
Conference
International Conference on Thermochemical Conversion of Biomass : 03/09/2013 - 06/09/2013
Note
Validerad; 2014; 20140520 (andbra); Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Öhrman, O., Weiland, F., Pettersson, E., Johansson, A.-C., Hedman, H. & Pedersen, M. (2013). Pressurized oxygen blown entrained flow gasification of a biorefinery lignin residue (ed.). Paper presented at . Fuel processing technology, 115, 130-138
Open this publication in new window or tab >>Pressurized oxygen blown entrained flow gasification of a biorefinery lignin residue
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2013 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 115, p. 130-138Article in journal (Refereed) Published
Abstract [en]

Renewable fuels could in the future be produced in a biorefinery which involves highly integrated technologies. It has been reported that thermochemical conversion (gasification) of lignocellulosic biomass has a high potential for end production of renewable biofuels. In this work, lignin residue from biochemical conversion of wheat straw was gasified in an oxygen blown pressurized entrained flow gasifier (PEBG) at 0.25–0.30 MWth, 0.45 < λ < 0.5 and 1 bar (g). A video camera mounted inside the PEBG was used to observe the flame during start up and during operation. Hydrogen (H2), carbon monoxide (CO) and carbon dioxide (CO2) were the main gas components with H2/CO ratios varying during the gasification test (0.54–0.63). The methane (CH4) concentration also varied slightly and was generally below 1.7% (dry and N2 free). C2-hydrocarbons (< 1810 ppm) and benzene (< 680 ppm) were also observed together with low concentrations of hydrogen sulfide (H2S, < 352 ppm) and carbonyl sulfide (COS, < 131 ppm). The process temperature in the reactor was around 1200 °C. The slag seemed to consist of Cristobalite (SiO2) and Berlinite (AlPO4) and Na, Ca, Mg, K and Fe in lower concentrations. Cooling of the burner will be necessary for longer tests to avoid safety shut downs due to high burner temperature. The cold gas efficiency and carbon conversion was estimated but more accurate measurements, especially the syngas flow, needs to be determined during a longer test in order to obtain data on the efficiency at optimized operating conditions. The syngas has potential for further upgrading into biofuels, but will need traditional gas cleaning such as acid gas removal and water gas shifting. Also, higher pressures and reducing the amount of N2 is important in further work.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-14070 (URN)10.1016/j.fuproc.2013.04.009 (DOI)000324154600017 ()2-s2.0-84879084024 (Scopus ID)d61f6678-a4bc-42ee-b55a-54752409d2cd (Local ID)d61f6678-a4bc-42ee-b55a-54752409d2cd (Archive number)d61f6678-a4bc-42ee-b55a-54752409d2cd (OAI)
Note
Validerad; 2013; 20130513 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Weiland, F., Hedman, H., Marklund, M., Wiinikka, H., Öhrman, O. & Gebart, R. (2013). Pressurized oxygen blown entrained-flow gasification of wood powder (ed.). Paper presented at . Energy & Fuels, 27(2), 932-941
Open this publication in new window or tab >>Pressurized oxygen blown entrained-flow gasification of wood powder
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2013 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 2, p. 932-941Article in journal (Refereed) Published
Abstract [en]

In the present study, an oxygen blown pilot scale pressurized entrained-flow biomass gasification plant (PEBG, 1 MWth) was designed, constructed, and operated. This Article provides a detailed description of the pilot plant and results from gasification experiments with stem wood biomass made from pine and spruce. The focus was to evaluate the performance of the gasifier with respect to syngas quality and mass and energy balance. The gasifier was operated at an elevated pressure of 2 bar(a) and at an oxygen equivalence ratio (λ) between 0.43 and 0.50. The resulting process temperatures in the hot part of the gasifier were in the range of 1100-1300 °C during the experiments. As expected, a higher λ results in a higher process temperature. The syngas concentrations (dry and N 2 free) during the experiments were 25-28 mol % for H2, 47-49 mol % for CO, 20-24 mol % for CO2, and 1-2 mol % for CH 4. The dry syngas N2 content was varied between 18 and 25 mol % depending on the operating conditions of the gasifier. The syngas H 2/CO ratio was 0.54-0.57. The gasifier cold gas efficiency (CGE) was approximately 70% for the experimental campaigns performed in this study. The synthesis gas produced by the PEBG has potential for further upgrading to renewable products, for example, chemicals or biofuels, because the performance of the gasifier is close to that of other relevant gasifiers

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-9196 (URN)10.1021/ef301803s (DOI)000315431900038 ()2-s2.0-84874187812 (Scopus ID)7c22211b-03de-49e7-9dd8-923739f7709f (Local ID)7c22211b-03de-49e7-9dd8-923739f7709f (Archive number)7c22211b-03de-49e7-9dd8-923739f7709f (OAI)
Note
Validerad; 2013; 20130302 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sjöberg, E., Sandström, L., Öhrman, O. & Hedlund, J. (2013). Separation of CO2 from black liquor derived syngas using an MFI membrane (ed.). Paper presented at . Journal of Membrane Science, 443, 131-137
Open this publication in new window or tab >>Separation of CO2 from black liquor derived syngas using an MFI membrane
2013 (English)In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 443, p. 131-137Article in journal (Refereed) Published
Abstract [en]

Membrane separation of CO2 from synthesis gas could be an energy efficient and simple alternative to other separation techniques. In this work, a membrane comprised of an about 0.7 µm thick MFI film on a graded alumina support was used to separate CO2 from synthesis gas produced by pilot scale gasification of black liquor. The separation of CO2 from the synthesis gas was carried out at a feed pressure of 2.25 MPa, a permeate pressure of 0.3 MPa and room temperature. In the beginning of the experiment, when the H2S concentration in the feed was 0.5% and the concentration of water in the feed was 0.07%, a CO2/H2 separation factor of 10.4 and a CO2 flux of 67.0 kg m-2 h-1 were observed. However, as the H2S concentration in the feed to the membrane increased to 1.7%, the CO2/H2 separation factor and the CO2 flux decreased to 5 and 61.4 kg m-2 h-1, respectively. The results suggest that MFI membranes are promising candidates for the separation of CO2 from synthesis gas.

National Category
Chemical Process Engineering
Research subject
Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-6850 (URN)10.1016/j.memsci.2013.05.008 (DOI)000320696000016 ()2-s2.0-84878640208 (Scopus ID)5278bd94-0fe0-4098-ad27-931ea3d626d9 (Local ID)5278bd94-0fe0-4098-ad27-931ea3d626d9 (Archive number)5278bd94-0fe0-4098-ad27-931ea3d626d9 (OAI)
Note
Validerad; 2013; 20130516 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Öhrman, O., Häggström, C., Wiinikka, H., Hedlund, J. & Gebart, R. (2012). Analysis of trace components in synthesis gas generated by black liquor gasification (ed.). Paper presented at . Fuel, 102, 173-179
Open this publication in new window or tab >>Analysis of trace components in synthesis gas generated by black liquor gasification
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2012 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 102, p. 173-179Article in journal (Refereed) Published
Abstract [en]

The only pressurized black liquor gasifier currently in operation is located in Sweden. The composition of the main components in the gas has been reported previously. The main components are H2, CO, CO2, N2, CH4, and H2S. In the present work, trace components in the gas have been characterized and the results are hereby reported for the first time. Samples were taken at two occasions during a one year period. The benzene concentration in the gas varied only slightly and the average concentration was 158 ppm. Benzene is formed by thermal cracking of the biomass. The COS concentration varied substantially and the average concentration was 47 ppm. The variations may be related to how the quench is operated. A few ppm of C2-hydrocarbons were also observed in the gas and the variation was probably a result of varying oxygen to black liquor ratio. No tars were observed in the gas. However, tar compounds, such as phenanthrene, pyrene, fluoranthene and fluorene were detected in deposits found on the pipe walls after the gas cooler. The concentration of particles in the synthesis gas was very low; <0.1 mg/N m3, which is comparable to the particulate matter in ambient air. Submicron particles were comprised of elements such as C, O, Na, Si, S, Cl, K, and Ca, and these particles probably originated from the black liquor. Larger particles were comprised mainly of Fe, S and Ni and these particles probably resulted from corrosion of steel in the plant pipe-work. In summary, the concentrations of trace components and particles in the gas are quite low.

National Category
Chemical Process Engineering Energy Engineering
Research subject
Chemical Technology; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-6236 (URN)10.1016/j.fuel.2012.05.052 (DOI)000308804500021 ()2-s2.0-84866456100 (Scopus ID)46f12668-cefd-4e72-b64b-8e3468736bdb (Local ID)46f12668-cefd-4e72-b64b-8e3468736bdb (Archive number)46f12668-cefd-4e72-b64b-8e3468736bdb (OAI)
Note
Validerad; 2012; 20120625 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Häggström, C., Öhrman, O., Rownaghi, A., Hedlund, J. & Gebart, R. (2012). Catalytic methanol synthesis via black liquor gasification (ed.). Fuel processing technology, 94(1), 10-15
Open this publication in new window or tab >>Catalytic methanol synthesis via black liquor gasification
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2012 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 94, no 1, p. 10-15Article in journal (Refereed) Published
Abstract [en]

Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16–0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C4, ethanol and dimethyl ether.

National Category
Chemical Process Engineering Energy Engineering
Research subject
Chemical Technology; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-4219 (URN)10.1016/j.fuproc.2011.09.019 (DOI)000300740100002 ()2-s2.0-80755176260 (Scopus ID)222cc047-e892-4afd-9efc-9f87f2d002f2 (Local ID)222cc047-e892-4afd-9efc-9f87f2d002f2 (Archive number)222cc047-e892-4afd-9efc-9f87f2d002f2 (OAI)
Note

Validerad; 2012; 20111114 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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