Polymer particles are expandable and produced by Nouryon. The production consists of polymerization, dewatering and drying. Dewatering of polymer particlesis an important part of the production process and have a large impact on how efficient the downstream process can be performed. An efficient dewatering enablesa fast and effective drying process and is therefore of great importance for a fastproduction process. Here, today, there are big variations. For mostpolymer particlegradesthe dewatering aid DEW1is added to the slurry. DEW1is a non-ionic surfactant that greatly increases dewatering abilities of slurry and thus increases speedof the downstream process. But, DEW1cannotbeused for allpolymer particlegrades due to regulations. Therefore, thosepolymer particlesdemand longer downstream times with higher production costs and higher energy consumption following. The aim ofthisdiploma work was to find an alternative dewatering aid which can be used for all polymer particle grades, has a good environmental profile and increases speed of the drying process. Several compounds weretestedin laboratory scaleduring this studyto investigatetheir effect ondry contentafter dewatering.One ofthem, DEW2, showedpromising features as an alternativedewatering aid which isalso bio-based. The highestdry content ofdewatered polymer particleslurrywith DEW2as dewatering aidwasXwt% dry polymer particles.This was2.2wt% higher dry content thanthe results achieved with DEW1.Also, the effect of heated polymer particleslurry and wash water on dry content wasinvestigatedduring this study. A strong relation between higher temperatures of especially wash water and increased dry content of dewatered polymer particleswasdetected. The highest dry content achieved was Xwt% dry polymer particlesfrom a test with slurry 20 °Cand wash water 80 °C. This was an increase in dry content with 26.9 % compared to the lowest dry content achieved. The lowest value was obtained when both slurry and wash water temperature was 20 °C, which during these tests gave a dry content of Xwt%. However, polymer particlesfrom testswith high temperatures showed signs of agglomerationof polymer particles on dispersion testwhich is not accepted for polymer particles of good quality.Two full scale production trialswere performed with wash water heated to 40 °C. No agglomerated polymer particleswereseen in the dried product, and the production speed increased with 18 respectively 11 % / Polymerpartiklar är expanderbara och producerade av Nouryon. Produktionen består av polymerisation, avvattning samt torkning.Avvattning avpolymerpartikelslurry är en stordel av efterbehandlingsprocessenoch det är viktigt att den kan genomföras effektivtför att minska tids-och energiåtgång. En väl fungerande avvattning främjar en snabb och effektiv torkprocess och är därför av stor betydelse för en snabb produktionsprocess. Idag finns stora variationergällande tidsåtgång beroende påvilken polymerpartikelskvalitet som produceras. Till de flesta polymerpartikelskvalitetertillsättsDEW1som fungerar somavvattningshjälpmedel. DEW1är en non-jonisk tensid som avsevärt förbättrar avvattningskapacitetenför polymerpartikelslurrynoch därmed förkortar efterbehandlingstidenoch därmed den totala produktionstiden. Dock kan inte DEW1användas föralla typer av polymerpartiklar.Det medför att produktionstidenförlängsför dessa kvaliteter, vilketleder till högre produktionskostnader samt en högre energiförbrukning. Syftet med det här examensarbetet varatt hitta ett alternativt avvattningshjälpmedelsom är miljövänligt,ökarhastigheten på avvattning-och torkningsprocessenoch som kan användas för alla typer av polymerpartiklar. Ett antal substansertestadesunder examensarbetet laborativt för att utvärdera deras effekt påtorrhalt på polymerpartiklarefter avvattning. Det biobaseradeavvattningshjälpmedlet DEW2såglovande ut med goda avvattningsegenskaper. Resultaten från försök med DEW2gav2.2wt% högre torrhaltän DEW1. Andra försök gjordes under examensarbetetför att undersöka sambandet mellan temperatur på polymerpartikelslurryoch tvättvatten mot torrhalt på avvattnade polymerpartiklar. Högre temperatur på speciellt tvättvatten gavhögre torrhalt, och den högsta torrhalten som uppnåddes vid försöken varXwt%med en slurrytemperatur på 20 °Coch tvättvattentemperatur på80 °C.Jämfört med det sämsta resultatet för torrhalt var det en ökningmed26.9%mot resultatet från tester utförda med slurry och tvättvattentemperatur 20 °C, som gav torrhalten Xwt%. Dessvärre visadedispersionstesterfrån testerutförda med temperaturer mellan 50 till 80 °Catt agglomerat bildatsi torkade polymerpartiklar.Två produktionstester utfördes där tvättvattnet värmdes till 40 °C. Här sågs inga problem med agglomerat i färdig produktoch produktionshastigheten ökade med 18 respektive 11 %.

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Copper is one of the most important metals globally, due to its wide application range and excellent chemical properties. Today it is commonly produced from chalcopyrite concentrates by the pyrometallurgical route with high emissions of greenhouse gasses. Tougher restrictions from authorities and governments on the industry give rise to research on other production routes for metals. Research has proven that copper production from chalcopyrite concentrates by the electrochemical route is possible. The project purposes were to produce copper from a chalcopyrite concentrate by removing sulfur during molten salt electrolysis and determine how the trace elements arsenic and antimony distributed. The chalcopyrite concentrate used in the trials was clean with low amount of impurities, therefore a dirty pyrite concentrate with higher content of impurities was used for determining the distribution of As and Sb. The electrolysis would roughly process 80 g of raw concentrate. The experimental set-up consisted of a pit-furnace with a stainless-steel crucible filled with 43.9 wt% NaCl and 56.1 wt% KCl.. The working electrode was composed of baskets made of molybdenum mesh containing either 2 or 4 briquettes of 20 g. The counter electrode was composed of a graphite block and the atmosphere was kept inert with nitrogen gas. The equimolar salt mixture was heated to 770 ° and a constant cell voltage at 2.5 V was applied until the current had decreased and stabilized.   It was concluded that the time-current curve for reduction of chalcopyrite followed a similar trend to that reported in the literature. The up-scaling of electrolysis of sulfuric concentrates was proven to be successful. Iron was captured on the inside of the sample holder and copper from the outside, separating the two elements into two fractions. This indicated that the separation of copper and iron occurred spontaneously, probably due to the magnetization of the reduced iron particles under the influence of the electromagnetic field induced by the electrolysis current.  Analyses by XRD, SEM, LECO and XRF proved that sulfur was reduced to < 0.2 wt% in the two product fractions. Most of the sulfuric compounds in the raw concentrates ended up as pure elements (As, Sb, Pd and Zn) in the copper product followed by the loss of the corresponding metallic elements in the exhaust gas due to evaporation of these elements.  Much knowledge of electrolysis of chalcopyrite was gained. To reach the original objectives further trials with an improved basket holder functioning as the cathode must be made. The results indicated that the electrochemical approach is suitable for copper production from chalcopyrite concentrates and further studies are recommended.

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. / Godkänd; 2005; 20061004 (ysko)

Global warming is believed to be caused by the extensive emission of greenhouse gases, for example carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas. To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossil fuels are limited and the oil and gas sources will eventually run out. Biogas and biobutanol are renewable biofuels which are interesting alternatives to fossil fuels. Biogas is produced during degradation of organic material forming a mixture of mainly methane and carbon dioxide with water as a common trace component. Biobutanol is produced from ABE (acetone, butanol and ethanol) fermentation of biomass. Purification of biogas and biobutanol is essential to increase the heat value of the fuels. Traditional purification processes are energy demanding and expensive. Therefore, other separation processes are currently sought for. Zeolites are promising alternatives due to their great potential both as selective adsorbents and as membranes. Due to the unique pore structure, zeolites are capable of separating components based on their adsorption properties. In the present work, single component adsorption of biogas components such as methane, carbon dioxide and water in zeolite ZSM-5 was studied as well as adsorption of water and butanol in silicalite-1 using in-situ ATR-FTIR spectroscopy. The method was successfully further used to study multicomponent adsorption. For single gas adsorption experiments, recorded infrared spectra of adsorbed methane, carbon dioxide and water showed characteristic, well separated, bands for each gas. Adsorbed concentrations were determined from the recorded infrared spectra. The Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work was in agreement with values reported in the literature. For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of methane, carbon dioxide and water using the single component adsorption isotherm parameters as input. In general, the IAST was shown to be a fairly good model for predicting the adsorbed concentrations of methane and carbon dioxide from binary mixtures. For the amount of adsorbed methane from mixtures including water, the IAST predicted the values fairly well. However, for mixtures containing water and carbon dioxide, the IAST could not fully describe the adsorption behavior of the two components. The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature. This indicates that the separation of carbon dioxide from biogas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that Na-ZSM-5 may be an effective membrane material for upgrading biogas. Moreover, butanol was preferentially adsorbed over water in silicalite-1, indicating that silicalite-1 may be a promising material for recovery of butanol from dilute water solutions. / Godkänd; 2015; 20150325 (linohl); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Lindsay Ohlin Ämne: Kemisk Teknologi /Chemical Technology Avhandling: An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites Opponent: Professor Niklas Hedin, Avd för materialkemi, Stockholms universitet, Stockholm Ordförande: Biträdande professor Mattias Grahn, Avd för kemiteknik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Luleå Tid: Fredag 29 maj kl 10.15 Plats: C305, Luleå tekniska universitet

To deal with the increasing demand of renewable fuels, more efficient processes for the production of biofuels are needed. Zeolite membranes have the potential to improve many existing processes that could be used for production of biofuels. Methanol is a potential biofuel that may be produced from synthesis gas in an equilibrium limited reaction. The production of methanol from synthesis gas could be improved by use of a membrane reactor, which could increase the conversion of synthesis gas to methanol per pass in the reactor. Methanol and several other biofuels can be prepared by first gasifying biomass to synthesis gas. Synthesis gas produced from biomass usually contains significantamounts of carbon dioxide that must be removed before methanol synthesis. However, commercial processes for carbon dioxide removal are very energy intense, and a membrane process could also improve this process and offer lower energy costs and less complicated and more compact equipment.In the present work, silicalite-1 and ZSM-5 membranes (NaZSM-5 and BaZSM-5) were successfully prepared on graded α-aluminasupports and evaluated for removal of carbon dioxide and hydrogen sulfide from synthesis gas. Both synthesis gas prepared from pure gas from gas cylinders and synthesis gas obtained from a black liquor pilot plant gasifier were used. The separations were performed at industrial relevant conditions, i.e. high pressures. It was found that the carbon dioxide fluxes were very high for carbon dioxide separation from synthesis gas free from water and hydrogen sulfide prepared from gas cylinders. Carbon dioxide fluxes up to 657 kg m-2 h-1 were observedfor a binary mixture of carbon dioxide and hydrogen. The high flux was a result of a thin membrane film, an open graded support, and ahigh pressure gradient over the membrane. A CO2/H2separation factor of 32.1 was observed at 2 ˚C and the selectivity was controlled by carbon dioxide adsorption, blocking the transport of hydrogen. The differences in carbon dioxide separation performance, observed for the different evaluated membranes, were likely due to differences in the carbon dioxide adsorption isotherms. The silicalite-1 membrane had a more favourable adsorption isotherm compared to the ZSM-5 membranes at these conditions, which resulted in larger difference in fractional surface loading between feed and permeate side of the membrane. It was also found that the carbon dioxide flux and separation factor decreased substantially when carbon dioxide and hydrogen sulfide was separated from synthesis gas derived from black liquor also containing water and hydrogen sulfide. This was probably an effect of competitive adsorption of hydrogen sulfide and water, which are probably blocking carbon dioxide molecules from permeating through the membrane. Furthermore, all-zeolite membranes (membranes consisting of both zeolite film and zeolite support) were prepared and evaluated for removal of carbon dioxide from synthesis gas in the present work. The membranes were carbon dioxide selective, but quite brittle, which made testing difficult. The zeolite supports used for all-zeolite membranes were prepared by collaborating researchers as an attempt to reduce crack formation in zeolite membranes, since the thermal expansion mismatch between the zeolite film and the membrane support will be minimized using this approach. Mathematical models of a traditional methanol synthesis process and two alternative membrane processes were also developed in the present work. Recorded experimental permeation data for a ZSM-5membrane was used as input to the models. The estimated performance of the traditional process was compared with a membrane reactor process (MRP) and a membrane module process (MMP). The mathematical model indicated that the MRP is the best alternative, since it enabled one pass operation, due to the highest conversion per pass. The MMP is however better from a practical point of view compared to the MRP since membrane and catalyst is separated and the membrane and reactor can be operated at their optimal respective temperatures and the membrane and catalyst can be replaced independently. By adding more membrane modules, the performance of the MMP will approach that of the MRP, to the price of higher complexity of the process. / <p>Godkänd; 2014; 20141007 (sjoeri); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Erik Sjöberg Ämne: Kemisk teknologi/Chemical Technology Avhandling: Zeolite Membranes for Production of Biofuels Opponent: Professor Joaquin Coronas, Chem. &amp; Environ, Eng. University of Zaragoza, Spanien Ordförande: Professor Jonas Hedlund, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 4 december 2014, kl 10.00 Plats: C305, Luleå tekniska universitet</p>

Nowadays, the need and interest for renewable sources of energy has increased. Biogas is a renewable source of energy that can be considered as a sustainable substitute for natural gas. Biogas is mainly composed of CH4 and CO2, and normally the CO2 content of the gas has to be reduced as it decreases the calorific value of the gas and it may also cause corrosion in pipes and other equipment. Most today’s technologies used for upgrading biogas have been adapted from upgrading of natural gas. However, these technologies are best suited for large scale operation; whereas, production of biogas is typically several orders of magnitude smaller. This leads to high costs for removal of CO2 from biogas and consequently, new efficient technologies for upgrading biogas should be developed. Membrane-based separations are generally considered as energy efficient and are suitable for a wide range in scale of production due to their modular design. Zeolite membranes have been singled out as especially attractive membranes for gas separations. In this work, we therefore study separation of CO2 from CH4 and H2 using zeolite MFI membranes.  The performance of a high-silica (Si/Al ca. 139) MFI membrane for CO2/CH4 separation was investigated in a wide temperature range i.e. 245 K to 300 K. The separation factor increased with decreasing temperatures as is typically the case for adsorption governed separations. The highest separation factor observed was about 10 at 245 K. The CO2 permeance was very high in the whole temperature studied, varying from ca. 60 × 10-7 mol s-1 m -2 Pa-1 at the lowest temperature to about 90 × 10-7 mol s-1 m -2 Pa-1 at the highest temperature studied. The CO2 permeance was higher than that reported previously in the open literature for this separation. Modeling of the experimental data revealed that the membrane performance was adversely affected by pressure drop over the support, whereas the effect of concentration polarization was small. Removing the former effect would improve both the permeance and selectivity of the membrane.  In order to investigate the impact of the aluminum content on the performance of MFI membranes for the CO2/CH4 separation, MFI membranes with different Si/Al ratios were prepared. Increasing the aluminum content makes the zeolite II more polar which should increase the CO2/CH4 adsorption selectivity. Again the effect of temperature on the performance was investigated by varying the temperature in a range almost similar as above. Altering the Si/Al ratio in MFI zeolite membranes indeed changed the separation performances. At the lower temperatures the separation performance increased with increasing aluminum content in the zeolite as a result of larger adsorption selectivity. However, as the temperature was decreased, the selectivity of the membrane with the highest aluminum content went through a maximum, whereas for the other membranes the selectivity continued to increase with decreasing temperature under the conditions studied. At the same time, the CO2 permeances were high for all membranes studied and for the membrane with the highest selectivity, the CO2 permeance increased from 65 × 10-7 to 100 × 10-7 mol s-1 m -2 Pa-1 with increasing temperature.  High-silica MFI membranes were also evaluated for CO2/H2 separation, which is critical for syngas purification and H2 production. The highest CO2 permeance at the feed pressure of 9 bar was about 78 × 10-7 mol s-1 m -2 Pa-1 at around 300 K, which is one or two order of magnitude higher than those reported previously in the literature. By decreasing the temperature, separation factor reached its highest value of 165 at 235 K.  In summary, zeolite membranes show great potential for CO2 separation from industrial gases, in particular for CO2 removal from synthesis gas. For the CO2/CH4 separation the selectivity of the MFI membranes should be improved or other frameworks relying on molecular sieving e.g. the CHA framework should be explored.

Alkylketene dimer, AKD, dispersions are used in the paper industry to obtain paper grades with a hydrophobic character i.e. resistance to sorption of water. AKD is used in neutral to alkaline internal sizing, pH in the interval of 6-9. AKD dispersions consist of wax particles emulsified in water. The particles are electrostatically and in most cases also sterically stabilized by cationic polyelectrolytes. The size of the particles is usually in the range of 0.5-2 µm in diameter. The idea of having cationic particles is that they are supposed to be deposited onto the negatively charged fiber surfaces, heterocoagulation. An increased usage of recycled pulp and a closure of the wet-end circuits of the paper machine will lead to increasing levels of dissolved and colloidal substances. These substances could be detrimental by affecting the AKD deposition onto the fiber material and the colloidal stability i.e. induce flocculation of sizing particles. Flocculation could lead to an inhomogeneous distribution of the sizing agent. The aims addressed in this thesis were the following: to investigate if high levels of shear, electrolyte concentration, anionic polymers and surfactants could affect the colloidal stability and induce flocculation of differently designed AKD dispersions to study the migration of AKD and the influence of extractives on the migration to study the sizing efficiency and retention using flocculated dispersions The colloidal stability of the dispersions was tested under shear by measuring the particle size distribution and the microelectrophoretic mobility. The migration of AKD through paper sheets with defined thickness and through paper sheets impregnated with extractives was analyzed with contact angle measurements on stored samples. The sizing efficiency of flocculated AKD was determined by measuring 60-second Cobb and contact angles on laboratory sheets. The retention of AKD was determined by quantitative analysis of the AKD content in the laboratory sheets using alkaline hydrolysis followed by solvent extraction and quantification with capillary gas chromatography. It was shown that anionic polymers and surfactants could seriously affect the colloidal stability of the dispersions, while shear and electrolyte concentration had a small influence. Dispersions with a high surface charge flocculates easier than dispersions with a low surface charge in process water from the wet-end of a linerboard paper machine. The flocculation rate is fast and occurs on the same time scale as deposition onto fines and fibers. The AKD agglomerates could be up to 30 µm in diameter even at high levels of shear. The AKD diffusion coefficient in paper sheets was estimated to be 10-11 m2/s at a temperature above the melting point of the wax. The results indicate that extractives do not interfere with the AKD migration. A reasonable explanation is that migration occurs via the vapor phase. It was also shown that sizing with flocculated AKD improved the sizing efficiency significantly due to increased retention. This clearly indicates that migration is efficient and that agglomerates can be used for internal sizing provided that the flocculation process is controlled. The conventional picture that the sizing agents must be very evenly distributed to achieve efficient sizing could, from the viewpoint of these results, be questioned. The process of sizing with pre-flocculated AKD dispersions is the subject of a patent application. Even if this thesis is focused on AKD dispersions, the obtained knowledge should be possible to transfer to other sizing systems. The emulsification process for rosin and ASA is based on the same principles as for AKD. / Godkänd; 2002; 20070222 (ysko)

This work concerns evaluation by permeation measurements and modeling of thin (<2µm) MFI molecular sieve membranes and, to a smaller extent, synthesis of such materials. The membranes have been synthesized on graded a-alumina microfiltration filters using The seed film method. Scanning electron microscopy and x-ray diffraction were used for characterization in addition to permeation measurements. Mathematical models describing membrane flux for real membranes and defect distributions were developed. Defect distributions were calculated from porosimetry data and were further used for prediction of single gas permeation characteristics for real membranes. The models confirm the experimental findings, with respect to ideal selectivities as a measurement of membrane quality. Membrane permeation simulations indicate increasing ideal selectivities, with increasing film thickness, for quotients containing SF6. Thereby a high quality membrane could possess low ideal selectivities. This finding was confirmed by comparing experimental data of several membranes with varying thickness. The correlation between multi component separation data and commonly used quality criteria was investigated. It was found that commonly used single gas permeation quotients (ideal selectivity) between light inorganic gases, especially those containing sulphurhexaflouride (SF6), is less appropriate for membrane quality measurement. The porosimetry experiment showed on the other hand a good agreement between experimental data and separation performance of the membranes, as expected. ZSM-5 membranes with low aluminum content and silicalite-1 membranes with similar material properties, such as defect distribution and thickness were evaluated with multi component hydrocarbon isomers permeation. The ZSM-5 membrane had lower permeances and a slightly better butane isomer separation performance than the silicalite-1 membrane. The latter membrane showed a minimum in separation selectivity between two C6 isomers whereas the ZSM-5 membrane showed an almost constant selectivity, independent of temperature, but with lower permeances. ZSM-5 membranes with a high aluminum content catalyzed the formation of diethylether and ethylen at temperatures exceeding 150°C from a water/ethanol mixture. The membrane separated a mixture of C4 isomers with good performance at elevated temperatures. However these membranes suffered from temperature instability problems. / Godkänd; 2002; 20070224 (ysko)

Molecular sieve films and colloidal particles may have great potential for further utilization in novel technological sophisticated applications such as structured catalysts, sensors and membranes. The work presented in this thesis concerns the synthesis molecular sieve films and the crystallization of zoned MFI materials for novel catalyst and sensor applications. The seeding method developed at the division has been modified for the preparation of MFI and FAU type films on a variety of steel substrates ranging from ordinary carbon steel to highly corrosion resistant stainless steel. The films were characterized by SEM, XRD and gas adsorption techniques. The results revealed that the type of steel did not affect the film morphology, the thickness or the preferred orientation of the crystals, whereas the thermal stability was dependent on the steel. Films on various stainless steel supports were stable during calcination, whereas films on carbon steel supports peeled off upon rinsing after calcination because a relatively thick magnetite/hematite film formed. Pre-calination of carbon steel improved the zeolite film stability upon calcination. Zoned MFI materials (colloidal zoned MFI crystals and zoned films) were synthesized in this work in order to improve the catalytic performance of MFI. A two-step crystallization method was developed to prepare zoned MFI materials, in which precursor ZSM-5 colloidal particles or film were grown in a silicalite-1 synthesis solution directly or after acid treatment. It was shown that zoned MFI materials did not form when the ZSM-5 surface had a high aluminum content. In this case, polycrystalline aggregates or a sandwich film formed due to secondary nucleation. After reducing the aluminum content to half by acid treatment of ZSM-5, secondary nucleation of new silicalite-1 crystals was inhibited and zoned MFI material was obtained. / Godkänd; 2003; 20070216 (ysko)