Black liquor gasification is a new process for recovery of energy and chemicals in black liquor from the Kraft pulping process. The process can be combined with catalytic conversion of syngas into motor fuels. The potential for motor fuel production from black liquor in Sweden is to replace about 25% of the current consumption of gasoline and diesel. For Finland the figure is even higher while for Canada it is about 14% and for the USA about 2%.

The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈ 19%) compared to the other fuels (2 – 8%) and thereby ≈ 16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it.

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.

A systematic investigation of two sets of defect free and defective ZSM-5 crystals with controlled thickness (T) between 30 and 400 nm and of their performances in methanol conversion was reported for the first time in the present work. The defect free ZSM-5 crystals with a thickness of 35 nm are by far the smallest ever reported and displayed superior activity, stability and selectivity to slower diffusing compounds, which resulted in high yield of e.g. gasoline and the 1,2,4-trimethylbenzene isomer with high octane number, as compared to the other studied catalysts. Almost only products forming in the zeolite pores were detected and consequently, the external surface must be nearly inactive. Strong correlations between T and deactivation rate were observed. Thick crystals deactivated much faster than thin crystals, probably due to formation of carbon species in the zeolite pores, which results in pronounced percolation effects and faster deactivation of the former. At comparable thickness, crystals with defects deactivated much faster than defect free crystals, due to formation of additional small molecular coke species in the former. Strong correlations between T and selectivity were also observed and assigned to control of diffusion resistance by crystal thickness.

The synthesis and catalytic testing of thin ZSM-5 films on glass and alumina beads is described. The thickness of the ZSM-5 films was controlled to 150, 350, 800 and 2300 nm. The samples were characterised by SEM, gas adsorption and p-xylene isomerisation and 1,3,5-tri-isopropyl benzene cracking test reactions. A reaction–diffusion model adequately described the p-xylene isomerisation data. Estimates of model parameters were obtained by fitting the model to the experimental data. In both cases, the reaction rate constant increased with increasing film thickness. The xylene reaction data showed that secondary reaction products increased as expected with increasing diffusion limitations, but the increase was less than that predicted by the variation of thickness only. The trends in the reaction data could be explained by more defects in the thicker films and/or partial poisoning of the zeolite by mobile support cations in thinner films and/or orientation effects.

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.

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.

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

MFI crystals or films with controlled thicknesses and different Si/Al ratios were grown on seeded cordierite monoliths using a clear synthesis mixture with template or a template-free gel. The materials were analyzed by scanning electron microscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis and sorption experiments using N2 or NO2 adsorbates. The films were uniformly distributed over the support surface. As expected, the specific monolayer N2 adsorption capacity (mol/gzeolite) was constant and independent of film thickness. The specific molar NO2 adsorption capacity was significantly lower than the specific molar monolayer N2 adsorption capacity, indicating that NO2 is adsorbed at specific sites rather than evenly distributed in a monolayer. A number of NO2 adsorption sites with varying strengths were observed by TPD experiments. At 30 °C, the amount of adsorbed NO2 in the MFI films increased with increasing Al and Na content as opposed to the N2 adsorption capacity, which was independent of these parameters. At 200 °C, the adsorbed amount of NO2 was lower than at 30 °C and apparently independent on Al concentration in the Na-MFI films. These results indicate that different mechanisms are involved in NO2 adsorption. NO2 may adsorb weakly on Na+ cations and also react with silanol groups and residual water in the zeolite, the latter two results in more strongly bound species. Upon NO2 adsorption, formation of NO was observed. This work represents the first systematic study of the effects of Al and Na content on NO2 adsorption in MFI films.

ZSM-5 films, with thicknesses between 150 and 2300 nm, supported on 3 mm diameter alumina beads are characterised in terms of their catalytic activity and selectivity for tri-isopropylbenzene cracking and para-xylene isomerisation at 450°C. A reaction-diffusion model adequately represents the experimental data and is used to estimate intrinsic reactivity and diffusion properties of the zeolite films. Results show that the external activity, overall activity and the diffusivity increase with increasing film thickness. The variation in reactivity and diffusivity, when compared to physio-chemical data, are a result of structural defects and non-homogeneities of the zeolite film. The measured diffusivities are within an order of magnitude of those extrapolated from literature. Thick zeolite films have the largest Thiele modulus as the increase in zeolite film thickness dominates over the structural defects. The largest selectivity improvements are observed for thick zeolite films

NOx adsorption in ZSM-5 films containing Na+, H+ or Ba2+ as counter ions was studied. NaZSM-5 films showed a superior NOx adsorption capacity over the entire temperature range (30-350 °C) in comparison with the other films. Besides the possibility to form strongly bound surface nitrate species, the presence of the Na+ ions in ZSM-5 resulted in a large enhancement of various weakly adsorbed species. In the HZSM-5 film, the NOx adsorption was mainly due to physisorption, surface nitric acid and nitrosium ion (NO+) formation. Besides weakly adsorbed species and surface nitric acid, the NOx adsorption in BaZSM-5 films also resulted in formation of strongly bound surface nitrate species. The nitrate species in the BaZSM-5 film were found to be resistant to NO exposure and were mainly formed through an NO2 disproportionation pathway.

NOx adsorption over a wide temperature range (30–350 °C) on monolith supported Na-ZSM-5 films were studied with a gas flow reactor. The nature of the adsorbed species was further investigated by in situ infrared spectroscopy. Depending on the adsorption temperature, three different ranges of thermally stable species were observed on Na-ZSM-5 films. In addition to the role of cationic sites and residual hydroxyl groups in zeolite frameworks, it was found that the formation of nitric acid plays an important role in NO2 adsorption. Nitrate species were formed during adsorption by two mechanisms. The nitrates formed via nitric acid and involving NO formation had lower thermal stability than those formed through an NO2 disproportionation reaction

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.

In this work we have studied different acidic zeolitic solid catalysts ZSM-5 with different crystal size, measuring their physical-chemical properties and correlating this with the activity, selectivity at different process condition during the conversion of methanol to dimethyl ether (DME) and gasoline boiling range hydrocarbons. The catalytic properties of these catalysts depended mainly on the crystal size and surface properties. Methanol feed in the DME and gasoline process is derived from black liquor-based syngas. The methanol to DME and gasoline process involves the conversion of black liquor syngas to crude methanol and methanol to DME and gasoline

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.

The seed-film method has been applied for the preparation of various materials of potential interest as structured molecular sieve catalysts. The method has proven to be very flexible and allows for the reproducible preparation of a number of molecular sieve–substrate combinations as well as the control of the materials’ properties of importance in catalytic applications such as zeolite loading, film thickness, film density and crystal orientation. The preparation of thin molecular sieve films on ceramic foams, α-alumina pellets and porous alumina supports as well as various metal surfaces is described. The preparation of zoned coatings with a compositional gradient is also discussed.

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

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.

In this study, well defined ZSM-5 films were prepared on monoliths, ceramic foams, alumina beads, glass beads and crushed quartz glass by further refinement of a method originally developed at the division of Chemical Technology, Luleå University of Technology. The supports were seeded with silicalite-1 seeds and hydrothermally treated, either at 75 °C or at 150 °C in a single or several steps. By adding sodium to the solution the aluminum concentration increased in the zeolite, which is beneficial for catalytic activity. Consequently, films with different Si/Al ratios could be prepared. The film thickness could be controlled from 110 nm to 9000 nm. Short hydrothermal treatments and use of multi-step synthesis was utilized to prevent excessive bulk crystallization and ultrasound treatment was beneficial in order to remove sedimented crystals on top of the zeolite films. The choice of support material and its influence on the performance of thin ZSM-5 film catalysts was examined by testing the reactivity of the zeolite- coated materials in two reactions; para-xylene isomerization and triisopropylbenzene cracking. ZSM-5 films with a thickness of 150, 350, 800 and 2300 nm, respectively, were prepared on alumina beads and quartz glass. Based upon the zeolite content, the films on quartz glass were much more active for para-xylene isomerization and for cracking of triisopropylbenzene, which is attributed to poisoning of the films on alumina due to impurities in the support. Model parameters were fitted to experimental results. The simulations indicated that thicker films contained a higher fraction of defects, which may be caused by open grain boundaries and cracks. These defects explain higher xylene diffusivities and higher triisopropylbenzene cracking activity for thicker films. As expected, thicker films possessed higher diffusion resistance than thin films despite the higher fraction of defects. The present work has given substantial and valuable fundamental understanding of the performance of thin molecular sieve film catalysts. These findings will be beneficial for development of materials that may be used in novel industrial applications.

A method originally developed at the division of Chemical Technology, Luleå University of Technology was tailored for the preparation of well-defined ZSM-5 films and zoned MFI films on supports suitable for catalysis and adsorption applications. Films were grown on monoliths, ceramic foams, alumina beads, soda glass beads and quartz glass. The supports were seeded with silicalite-1 crystals and hydrothermally treated in a single or several steps. The materials were evaluated by scanning electron microscopy, x-ray diffraction, N2 and NO2 sorption, x-ray photoelectron spectroscopy, ICP-AES, p-xylene isomerization and cracking of 1,3,5-tri-isopropylbenzene. The thickness of the continuous films could be controlled from 110 nm to 9 µm. Zoned MFI films were prepared from precursor ZSM-5 films by overgrowth with silicalite-1. A multi-step synthesis protocol was used to prevent excessive bulk crystallization. Ultrasound treatment was beneficial for removal of loosely attached crystals on top of the zeolite films. Defects such as cracks and open grain boundaries were observed by SEM and in concert, mesopores were observed by N2 sorption. Model parameters were fitted to experimental data from catalytic test reactions and these parameters indicated that thicker films contained more defects, probably in the form of open grain boundaries and cracks (mesopores) as observed by SEM and N2 sorption. Films supported on quartz were more catalytically active than films on alumina and soda glass. This was attributed to partial poisoning of the acid sites in the films on the latter two substrates, probably due to solid-state ion exchange of impurities such as alkali metals from the alumina and soda glass support to the film. As expected, thicker films possessed higher diffusion resistance than thin films. Surprisingly, a higher external activity was observed after zoning. This was attributed to formation of mesopores, migration of aluminum from the precursor ZSM-5 film to the external surface, and increased surface roughness upon zoning. ZSM-5 films supported on monoliths were successfully tested for NO2 sorption. As expected, the adsorption capacity per g zeolite was independent of film thickness. Formation of NO was observed as a result of NO2 adsorption on strong sites. Thicker films resulted in higher diffusion resistance as expected. The present work has resulted in substantial and valuable new fundamental understanding of the performance of thin molecular sieve film catalysts and adsorbents. These findings may facilitate development of novel materials for industrial applications.

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.

Alumina and quartz supports were coated with well-defined precursor ZSM-5 films ranging from 350 nm to 2300 nm in thickness. The precursor samples were subsequently treated with hydrochloric acid and hydrothermally treated in a silicalite-1 synthesis solution in order to obtain zoned MFI films. A dense, but rougher, silicalite-1 film was formed on top of the smooth precursor ZSM-5 film after two hydrothermal treatments. Defects such as open grain boundaries and cracks were observed by SEM and in concert, mesopores were detected by gas adsorption in the precursor and zoned films. The mesopore volume per gram film increased after acid treatment and zoning, probably due to that a small fraction of the zeolite film dissolved in this process. As expected, the aluminum concentration at the surface of the un-calcined zoned film was lower compared to that at the surface of the calcined precursor ZSM-5 film. However, after calcination of the zoned film, the concentration of aluminum at the surface increased, probably due to aluminum migration from the precursor film to the surface of the zoned film during calcination. The aluminum concentration at the surface of the calcined zoned film was even higher than at the surface of the calcined precursor ZSM-5 film. Consequently, the triisopropylbenzene cracking rate constant did not decrease as expected after zoning, probably due to the increased amount of defects and/or aluminum migration. The p-xylene diffusivity increased after zoning, probably due to the formation of defects, whereas the xylene isomerization rate constants were unaffected, as expected.

Alumina beads were coated with ZSM-5 films ranging from 150 nm to 2300 nm ill thickness. The ZSM-5 boated alumina beads were Subsequently hydrothermally treated in a silicalite-1 synthesis solution ill two steps Whereupon a dense silicalite-1 film was formed oil top of the ZSM-5 film. The materials were tested with two probe reactions and the reactivity was compared before and after coating with silicalite-1. As expected, the para-xylene (pX) isomerization reactivity showed no change for samples with and without the top layer of silicalite-1 for equal amounts Of zeolite. Surprisingly, the triisopropylbenzene (TIPB) conversion did not decrease after the silicalite-1 film was introduced. As measured by XPS, the aluminum concentration at the Surface of the uncalcined silicalite-1 film surface was lower compared to that at the Surface of the calcined ZSM-5 film. However, after calcination the concentration of aluminum was higher at the silicalite-1 film surface than at the ZSM-5 film Surface. These results Suggest that aluminum migrates from the ZSM-5 film into the silicalite-1 film during calcination and testing which results in all active top layer.

Alumina beads, quartz and soda glass were coated with ZSM-5 films using a seeding method. Films with a thickness of 150, 350, 800 and 2300 nm were prepared. The catalysts were tested by para-xylene (pX) isomerization and triisopropylbenzene (TiPB) cracking. Model parameters, i.e. rate constants and diffusivities, were fitted to experimental results. The films on quartz glass were much more active for pX isomerization and for cracking of TiPB, which was also reflected by the model parameters. Low and zero rate constants for alumina and soda glass supported catalysts, respectively, were attributed to poisoning of the ZSM-5 film due to impurities in these supports. Larger diffusivity in quartz supported catalysts and thick films was attributed to more defects in the film.

Well-defined ZSM-5 films were prepared on cordierite monoliths using the seed film method. The monoliths were seeded with silicalite-1 seeds and hydrothermally treated either at 75 or at 150 °C in a single or several steps. By adding sodium hydroxide to the solution, the aluminum concentration in the zeolite increased. Consequently, films with different Si/Al ratios were prepared. The film thickness could be controlled from 110 nm to 9 μm. Multi-step synthesis was used to prevent bulk crystallization and ultrasound treatment was found to be beneficial (in order) to remove sedimented crystals on the top of the coatings. The zeolite-coated monoliths were active for p-xylene isomerization, and the test results indicated that the films became less deactivated than the films prepared on alumina beads.

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.