<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 7 uppsatser.</p> / digitalisering@umu

The current societal needs for fuels and chemical commodities strongly depend on fossil resources. This dependence can lead to economic instabilities, political problems and insecurity of supplies. Moreover, global warming, which is associated with the massive use of fossil resources, is a dramatic “collateral damage” that endangers the future of the planet. Biomass is the main renewable source available today that can, produce various liquid, gaseous and solid products. Due to their lignocellulosic origin are considered CO2 neutral and thus can generate CO2 credits. Biomass processing can meet to the challenge of reducing of fossil resources by producing a liquid feedstock that can lessen the “fossil dependence” and /or meet the increased demand via a rapidly emerging thermochemical technology: pyrolysis. The ultimate goal of this process is to produce liquid with improved properties that could directly be used as liquid fuel, fuel additive and/or feedstock in modern oil refineries and petrochemical complexes. However, the liquids derived from biomass thermal processing are problematic with respect to their handling and end use applications. Thus, alternative routes of advanced liquid feedstock production are needed. Heterogeneous catalysis has long served the oil refining and petrochemical industries to produce a wide range of fuels and products. The combination of biomass pyrolysis and heterogeneous catalysis (by bringing in contact the produced vapours/liquids with suitable catalysts) is a very promising route. In this dissertation, the exploitation of biomass to produce of liquid feedstock via pyrolysis over a multifunctional catalyst and in a steam atmosphere is investigated.  Steam pyrolysis in a fixed bed reactor demonstrated that steam can be considered a reactive agent even at lower temperatures affecting the yields and the composition of all the products. The devolatilisation accelerates and the amount of final volatile matter in the char. Fast pyrolysis in the presence of steam results in improved and controlled thermal decomposition of the biomass; higher liquid yields and slightly deoxygenated liquid products are also obtained. Steam pyrolysis over a bi-metallic Ni-V catalyst can produce liquids of improved quality (lower O content) and also provide routes for selective deoxygenation. However, a decrease in liquid yield was observed. The combination of metal and acid catalysts (Ni-V/HZSM5) shows enhanced deoxygenation activity and increased H preservation in the produced liquid. The final O content in the liquid was 12.83wt% at a zeolite (HZSM5) loading of~75wt%; however, the yield of the obtained liquid was substantially decreased. Moreover, increased coke formation on the catalyst was observed at highest zeolite rate. The increased catalyst space time (τ) results in a lower liquid yield with reduced oxygen (7.79 wt% at τ =2h) and increased aromatic content. The coke deposited per unit mass of catalyst is lower for longer catalyst space times, while the char yield seems to be unaffected. The evaluation of the stability of the hybrid catalyst showed no significant structural defects and activity loss when the catalyst was regenerated at a low temperature (550οC). / Det nuvarande samhällets behov av bränslen och kemiska produkter är starkt knutet till fossila resurser. Detta beroende kan leda till ekonomisk instabilititet, politiska svårigheter och osäker leveranssäkerhet. Dessutom riskeras allvarliga skador i framtiden på grund av global uppvärmning, vilket är relaterat till det ökande och massiva användandet av fossila bränslen.   Biomassa är en förnybar resurs som är tillgänglig idag, möjlig att utnyttja för produktion av diverse flytande, gasformiga och fasta produkter. Dessa produkter, beroende på biogeniskt ursprung, betraktas som koldioxidneutrala och kan därför generera koldioxidkrediter. Processande av biomassa kan möta utmaningen av minskad fossilbränsleanvändning, genom produktion av flytande råvara som kan reducera beroendet och/eller möta ökad efterfrågan, via en snabbt expanderande termokemisk teknik - pyrolys.    Det slutgiltiga målet med en sådan process är att producera en flytande produkt med förbättrade egenskaper som direkt skulle kunna användas som flytande bränslen, bränsleadditiv och/eller som råmaterial i moderna oljeraffinaderier och petrokemiska komplex. Vätskor som utvinns från termiska processer är problematiska med avseende på hantering och slutanvändningen i olika applikationer, därmed behövs olika spår för produktion av avancerade flytande råvaror. Heterogena katalysen har länge tjänat raffinaderi- och petrokemisk industri, som producerar ett brett utbud av bränslen och produkter, lämpliga för säker användning. Kombinationen av biomassapyrolys och heterogen katalys  (genom att bringa pyrolysångorna i kontakt med en lämplig katalysator) är ett väldigt lovande spår. I denna avhandling undersöks användningen av biomassa för produktion av flytande råvara, via pyrolys över en flerfunktionel katalysator i ångatmosfär. Ångpyrolys i en fastbäddsreaktor visade att ånga kan betraktas som ett reaktivt medium,  även vid låga temperaturer, som påverkar utbyten och sammansättning av alla produkter. Avgasningen sker snabbare och den slutliga flykthalten i kolresterna blir lägren vid användning av ånga. Snabbpyrolys i ångatmosfär resulterar i förbättrad och mer kontrollerad termisk nedbrytning av biomassa, vilket ger ett högre vätskeutbyte och en något deoxygenerad flytande produkten. ångpyrolys i kombination med bimetalliska NiV-katalysatorer, ger upphov till en flytande råvara med förbättrad kvalitet och selektiv deoxygenering. Dock med ett minskande utbyte som följd. Kombinationen av metall och en sur katalysator (Ni-V/HZSM5) visade förstärkt deoxygenering med bibehållen vätehalt i den flytande produkten. Den slutliga syrehalten i vätskan var 12.83 vikt% vid en zeolithalt (HZSM5) på 75 vikt%, dock med ett kraftigt minskande vätskeutbyte. Dessutom noterades ökad koksbildning på katalysatormaterialet med den högsta zeolithalten. Ökad rymd-tid  för katalysatorn (τ) ger ett lägre vätskeutbyte med reducerad syrehalt (7.79 vikt% vid τ=2h) och ökad aromathalt. Koksbildning på ytan, per massenhet katalysatormaterial, minskade vid längre rymd-tider medan utbytet av kolrester förblev opåverkat.  Undersökningen av stabiliteten hos hybridkatalysatorn visade inga strukturella defekter och ingen signifikant minskad aktivitet efter regenerering vid låg temperatur (550οC). / Οι σύγχρονες ανάγκες της κοινωνίας για παραγωγή υγρών καυσίμων και χημικών προϊόντων εξαρτώνται από τους ορυκτούς πόρους. Αυτή η εξάρτηση μπορεί να οδηγήσει σε οικονομικά προβλήματα, πολιτκή αστάθεια, όπως επίσης και αβεβαιότητα στις προμήθειες της ενεργειακής εφοδιαστικής αλυσίδας. Επιπροσθέτως, μια δραματική «παράπλευρη απώλεια» η οποία θέτει σε κίνδυνο το μέλλον του πλανήτη είναι η υπερθέρμανσή του, η οποία έχει συσχετισθεί με την εκτεταμένη χρήση ορυκτών πόρων. Σήμερα, η βιομάζα είναι η μόνη ανανεώσιμη πηγή από την οποία μπορούν να παραχθούν υγρά, αέρια και στερεά προϊόντα, που λόγω της λιγνοκυταρρινικής τους προελεύσεως, η συνεισφορά τους στις εκομπές CO2 θεώρειται μηδενική. Η θερμοχημική επεξεργασία της βιομάζας συνεισφέρει στον περιορισμό της χρήσης ορυκτών πόρων, με την παραγωγή υγρών προϊόντων, τα οποία μπορούν να μειώσουν την εξάρτηση ή /και την αυξημένη ζήτηση μέσω μιας ταχέως αναπτυσόμενης τεχνολογίας, της πυρόλυσης. Στόχος της διεργασίας είναι η παραγωγή υγρών προϊόντων με ιδιότητες, που επιτρέπουν την απευθείας χρήση τους ως υγρά καύσιμα ή ως πρώτη ύλη, για την παραγώγη χημικών προϊόντων σε συγχρονες μονάδες διύλισης πετρελαίου και σε πετροχημικά συγκτροτήματα. Εν τούτοις, τα υγρά προϊόντα της θερμικής διάσπασης (πυρόλυση) είναι προβληματικά στη διαχείρηση και στις τελικές τους εφαρμογές, λόγω της σύστασής τους. Ως εκ τούτου, απαιτούνται νέες τεχνικές για παραγωγή προηγμένων υγρών προοϊόντων. Η ετερογενής κατάλυση έχει επιτυχώς εφαρμοσθεί στην πετρελαϊκή και χημική βιομηχανία, παράγοντας ένα μεγάλο εύρος προϊόντων. Ο συνδυασμός της με την πυρόλυση (φέρνοντας σε επαφη τα υγρά/ατμούς με κατάλληλο καταλύτη) αποτελεί μια πολλά υποσχόμενη ενναλακτική. Στην παρούσα διατριβή μελετάται η αξιοποίηση βιομάζας για παραγωγή υγρών προϊόντων μέσω καταλυτικής πυρόλυσης, με χρήση πολυλειτουρικού καταλύτη (multi-functional catalyst) υπό την παρουσία ατμού. Η χρήση ατμου κατά τη διαρκειά πυρόλυσης βιομαζας σε αντιδραστήρα σταθερής κλίνης, μεταβάλει τη σύσταση των επιμέρους προϊόντων. Η παρουσία ατμού έχει ως αποτέλεσμα την ταχύτερη αποπτητικοποίηση του υλικού, ενώ παράλληλα η περιεκτικότητα του υπολειπόμενου εξανθρακώματος σε πτητικά είναι μικρότερη. Τα πειραματικά αποτελέσματα ταχείας πυρόλυσης σε αντιδραστήρα ρευστοστερεάς κλίνης δείχνουν ό,τι η χρήση ατμού βελτιώνει την θερμική διάσπαση της βιομαζας, αυξάνοντας την απόδοση σε υγρά προϊοντά, ενώ παράλληλα βοηθάει στην αποξυγόνωσή τους. Ο συνδυασμός της πυρόλυσης υπό την παρουσία ατμού και διμεταλλικού καταλύτη νικελίου–βαναδίου μπορεί να  βελτιώσει την ποιότητα των παραγόμενων υγρών (αποξυγόνωση) με παραλλήλη μείωση της απόδοσής τους, ενώ μπορεί να  παράγει προϊόντα εκλεκτικής αποξυγόνωσης. Συνδυασμός μεταλλικών και ζεολιθικών καταλυτών (Ni-V/HZSM5) εμφανίζει βελτιωμένη δραστικότητα στις αντιδράσεις αποξυγόνωσης, με παράλληλη συγκράτηση υδρογόνου (Η) στα υγρά προϊόντα. Η τελική περιεκτικότητα των υγρών προϊόντων σε οξυγόνου (Ο) μετά από 90 min αντίδρασης είναι 12.83 wt%, με περιεκτικότητα ζεόλιθου (ΗZSΜ5) ~75 wt% στον καταλύτη. Ωστόσο, η αυξηση της περεικτικότητας σε ζεόλιθο έχει ως αποτέλεσμα την αύξηση των επικαθήσεων άνθρακα επάνω στον κατάλυτη, καθώς και την σημαντική μειώση της απόδοσης των υγρών προϊόντων (24.35wt% επι ξηρής βιομάζας).  Η αύξηση του χώρου χρόνου του καταλύτη (τ) έχει ως αποτέλεσμα: τη μείωση των υγρών προϊόντων, τη μείωση του περιεχόμενου Ο στα υγρά προϊόντα (7.79 wt% at τ =2h), την αύξηση των αρωματικών υδρογονανθράκων και τη μείωση του επικαθήμενου κωκ ανά μονάδα μάζας καταλύτη. Η απόδοση του εξανθρακώματος παρέμεινε πρακτικά αμετάβλητη. Η αναγέννηση του υβριδικού καταλύτη σε χαμηλές θερμοκρασιές (550οC) δεν επέφερε σημαντικές δομικές αλλαγές και απώλεια δραστικότητας. / <p>QC 20140306</p>

The purpose of this study is to develop catalysts for conversion of synthesis gas (H₂ and CO) to higher alcohols, primarily ethanol and propanol. Crude oil is consumed at a rate of more than 20 million barrels a day in the United States, mainly for producing fuels and chemical feedstocks. However, the total amount of crude oil is limited, and alternative ways of producing alcohols as precursors for chemical feedstocks are desirable. In this study, using a known K/MoS₂/metal oxide catalyst as the starting point, two different approaches were explored to improve catalytic properties: 1) Co promotion on K/MoS₂/mixed metal oxide (MMO) catalysts, and 2) Preparation of K/MoS₂/metal oxide catalysts with molybdenum carbide as a precursor, instead of molybdenum oxide. With respect to Co promotion on K/MoS₂/MMO catalysts, the effect of varying the Co content in the K/Mo-Co/MMO catalysts prepared by a co-impregnation method did not produce significant changes in catalytic acitivities or selectivities. It was due to the premature precipitation of cobalt molybdate during synthesis. Cobalt molybdate precipitation can generally be prevented by using water as a solvent, but this approach is not appropriate for this study because of the use of hydrotalcite-derived mixed metal oxide as the support. Co loadings on K/Mo/MMO-Co catalysts did not change selectivities significantly, either. However, they changed catalytic activities, represented by gas hourly space velocity (GHSV) required to obtain 8% conversion while maintaining high selectivities for higher alcohols. As a result, C ₂₊ alcohol productivities reached 0.01g(alcohol)/g(catalyst)/hr with Co loadings higher than 8%. With respect to using Mo2C as the precursor of Mo species instead of MoO3, comparisons between catalysts with different precursors for Mo species and different pretreatments were investigated. In this study, both K/Mo catalysts supported on MgO and α-Al₂O₃ showed similar tendencies of catalytic activities and selectivities. The highest C₂₊ alcohol selectivities and productivities were obtained on presulfided MoO₃ catalysts on both supports. In comparison of K/Mo ₂C catalysts with different pretreatments, higher C₂₊ alcohol selectivities and lower MeOH selectivities were obtained on presulfided catalysts compared to non-pretreated catalysts.

The purpose of study is to research the development of electric vehicle technology in the United States. This study describes the United States public policies towards electric vehicle technology and system of innovation approaches. The government roles with the help of national system of innovation have been also covered in this study. The point of departure was the study of available literature and U.S energy policy acts which illustrates that the break-through in electric vehicles still not only depended on better battery technology and infrastructure for charging stations but also on social, economic and political factors. The important actors involved in the process are both at local and international level are private firms, governmental departments, research and development (R&amp;D) institutes, nongovernment organizations (NGO’s) and environmental organizations etc. The arguments which are put forward in the background of development of such technologies are to reduce dependence on foreign oil and to reduce emissions of harmful gasses.

Interest in planting Jatropha curcas L. for the production of biodiesel is growing exponentially. The properties of the crop and its oil have persuaded investors to consider J. curcas oil as a substitute for fossil fuels. However, this plant is still undomesticated, basic agronomic properties are not thoroughly understood and the environmental effects on growth have not been investigated. This thesis investigated different approaches that may contribute to improving the productivity of this plant. Seed germination and methods of propagation are usually the first consideration in any plant development programme. The effects of aerosol smoke, smoke water, potassium nitrate, naphthalene acetic acid and indole-3-butyric acid on germination and seedling growth of J. curcas were investigated. Seed coat removal accelerated water imbibition and germination occurred within 48 h. Seeds exposed to aerosol smoke failed to germinate over the whole study period of three months. There were no significant differences in total germination between the treatments and the untreated control (intactand shelled-seed). However, shelled-seeds had a shorter mean germination time. The seedlings were subsequently sown in trays under shade house conditions and different seedling growth traits measured after three months. Smoke water, potassium nitrate and naphthalene acetic acid produced significantly heavier seedlings with longer stems and roots, wider stems and a higher vigour index compared to the control treatments. Smoke water, potassium nitrate and naphthalene acetic acid stimulated seedling growth and vigour of J. curcas. This opens the possibility of applying these treatments to produce quality seedlings for large scale planting and accelerated plant establishment in production orchards. Effective pollination is a prerequisite for many crops to increase seed-set and fruit production. Experiments were conducted to determine factors that could influence seed production in this potential biofuel seed crop. Controlled pollination experiments showed that plants required pollinator visits for seed production and were genetically selfx compatible. Pollen-supplementation did not lead to increased fruit set, suggesting that seed production in the study population was not pollen-limited. Both male and female flowers produced nectar and were highly attractive to honeybees. These insects were effective pollinators of J. curcas, as shown by experiments in which flowers exposed to single or multiple visits by honeybees set significantly more fruit than those from which visits were precluded. Pollinator-mediated self-pollination led to marginally lower levels of seed production relative to cross-pollination. Progeny from selfed plants had significantly shorter roots than progeny of outcrossed plants. However, in general, there was little evidence of inbreeding depression. The present results provide empirical evidence that honeybees are effective pollinators of J. curcas. Fruit arising from selfpollination were almost as numerous and as large as those arising from crosspollination, suggesting that promotion of cross-pollination does not have to be a priority in orchard management for fruit yield. Manipulation of pollen development and function is of vital importance for crop development and improvement. Experiments were conducted to investigate pollen viability, in vitro pollen germination and in vivo pollen tube growth in J. curcas. Light and fluorescence microscopy were employed to examine the different developmental stages. It was possible to determine pollen viability and distinguish between fresh and dead pollen using 2,3,5-triphenyltetrazolium chloride (TTC). Pollen germination was significantly higher in an agar-based medium composed of sucrose, boric acid and calcium nitrate compared with the control treatment (distilled water). Supplementation of IAA to the different media significantly increased pollen germination and pollen length compared with the control treatment. Pollen from hermaphrodite flowers had a lower viability, lower germination rates and shorter pollen tubes, with abnormal shapes, compared to the pollen from male flowers. Pollen tubes from both self- and crosspollinated flowers entered the ovary within 8 hours after pollination (HAP). However, at 6 HAP, the pollen tube length and growth rate were significantly higher in crosscompared to self-pollinated pollen. Our results suggest that TTC is a reliable test for pollen viability; boric acid, calcium nitrate, sucrose and addition of IAA are essential and beneficial for pollen germination in this plant. Pollen germination and pollen tube growth were not inhibited, nor interfered with, as a result of self-pollination treatments. During, both types of pollination, fertility is maintained as evidenced by ovule penetration by pollen tubes. This suggests that type of pollination has no influence on the success of fertilization in J. curcas. Manual pruning is one of the major management practices in commercial plantations of J. curcas, resulting in production of more branches and thus increased potential for more inflorescences leading to a higher seed yield. Experiments were conducted to determine the response of J. curcas plants to manual pruning under summer and winter conditions. The results showed that manual pruning under both conditions significantly increased the number of branches per plant. However, there were no significant differences in number of branches between winter and summer manual pruning. Winter pruning, however, had a significantly wider crown diameter compared to the control and summer pruning. Both treatments produced significantly less fruits/per plant in the subsequent season compared to the un-pruned control. This study revealed that winter and summer manual pruning may be suitable practice to promote branching. Manual pruning, however, is time consuming, labour intensive and expensive. A study was conducted to determine the potential of different plant growth regulators (PGRs) to increase the number of lateral branches of J. curcas plants. A single foliar application of BA (benzyladenine) at 12 mmol l-1 significantly increased branches in both the pot (4) and field (13.2) trials compared to manual pruning (MP) (1.8 and 5.7 respectively) and control (no new branches) plants. In the field, treatment with TIBA (2,3,5-triiodobenzoic acid) (1 mmol l-1) significantly increased the number of branches (15.9) after seven months from application. Of all the PGRs examined, DK (Dikegulac) (2,3:4,6-di-Oisopropylidene- 2-keto-L-gulonic acid) at 2 mmol l-1 produced the maximum number of branches (18) in the field seven months after application. Concentrations of 2 and 3 mmol I-1 of MH (Maleic hydrazide) (1,2-dihydro-3,6-pyridazinedione, coline salt) significantly increased the number of branches, four and seven months after spraying in both the pot trial in the shade house and field respectively. Under field conditions J. curcas plants responded better to all the PGRs (DK < TIBA < BA < MH) when treated once, with insignificant variations of other growth parameters. This study indicates that a single foliar application of PGRs under field conditions can be an alternative method to MP for increasing the number of lateral branches of J. curcas plants. The field chemical pruning experiment was continued to determine the potential subsequent effects of the different PGRs on seed production. In the subsequent year following the single foliar application, the parameters of flowering, fruit set, fruit characteristics, total oil content and free fatty acid (FFA) content were evaluated. Number of flowers per plant and number of fruits per bunch were significantly affected by the different treatments. However, there were no variations in the degree of fruit set. A single foliar application of BA (6-benzylaminopurine) produced more flowers per plant, more fruits per bunch, heavier and bigger fruits and seeds with more oil compared to MP (manual pruning). TIBA (2,3,5-Triiodobenzoic acid) produced significantly more flowers per plant and heavier fruits compared to the control and MP treatments. However, it produced significantly bigger fruits with more seeds and a higher oil content than MP. DK (Dikegulac) (2,3:4,6-di-O-isopropylidene-2-keto-Lgulonic acid) produced more flowers per plant and seeds with high oil content compared to the control and MP. However, it produced more fruit per bunch and more seeds per fruit compared to MP. MH (Maleic hydrazide) produced more flowers per plant, heavier and bigger fruits with numerous, heavier and oil rich seeds compared to the control and MP. This study indicates that foliar application of PGRs can be used in J. curcas to increase seed production and improve fruit quality. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

This thesis reports a model to predict the auto-ignition time of single droplets of n-paraffin fuel mixtures using the method of continuous thermodynamics. The model uses experimental data for pure fuels to fit rate parameters for a single-step global chemical reaction equation; from this, correlations for rate parameters as a function of species molecular mass are derived, which are integrated to produce a continuous thermodynamics expression for mixture reaction rate. Experiments were carried out using the suspended droplet-moving furnace technique. The model was then tested and compared to experimental data for three continuous mixtures with known compositions: one ranging from ¬n-octane to n-hexadecane, the second ranging from n-dodecane to n-eicosane, and the third being a combination of the first two mixtures to produce a “dumbbell” mixture. Discrete and continuous mixture models of the ASTM standard distillation test were compared to design the experimental mixtures and provide the distribution parameters of the continuous mixtures intended to simulate them. The results of calculations were found to agree very well with measured ignition times for the mixtures.

Production of high-quality syngas from biomass gasification in a dual fluidised bed gasifier (DFBG) has made a significant progress in R&amp;D and Technology demonstration. An S&amp;M scale bio-automotive fuel plant close to the feedstock resources is preferable as biomass feedstock is widely sparse and has relatively low density, low heating value and high moisture content. This requires simple, reliable and cost-effective production of clean and good syngas. Indirect DFBGs, with steam as the gasification agent, produce a syngas of high content H2 and CO with 12-20 MJ/mn3 heating value. The Mid Sweden University (MIUN) gasifier, built for research on synthetic fuel production, is a dual fluidised bed gasifier. Reforming of tars and CH4 (except for methanation application) in the syngas is a major challenge for commercialization of biomass fluidised-bed gasification technology towards automotive fuel production. A good syngas from DFBGs can be obtained by optimised design and operation of the gasifier, by the use of active catalytic bed material and internal reforming. This thesis presents a series of experimental tests with different operation parameters, reforming of tar and CH4 with catalytic bed material and reforming of tar and CH4 with catalytic internal reformer.   The first test was carried out to evaluate the optimal operation and performance of the MIUN gasifier. The test provides basic information for temperature control in the combustor and the gasifier by the bed material circulation rate.    After proven operation and performance of the MIUN gasifier, an experimental study on in-bed material catalytic reforming of tar/CH4 is performed to evaluate the catalytic effects of the olivine and Fe-impregnated olivine (10%wtFe/olivine Catalyst) bed materials, with reference to non-catalytic silica sand operated in the mode of dual fluidised beds (DFB). A comparative experimental test is then carried out with the same operation condition and bed-materials but when the gasifier was operated in the mode of single bubbling fluidised bed (BFB). The behaviour of catalytic and non-catalytic bed materials differs when they are used in the DFB and the BFB. Fe/olivine and olivine in the BFB mode give lower tar and CH4 content together with higher H2+CO concentration, and higher H2/CO ratio, compared to DFB mode. It is hard to show a clear advantage of Fe/olivine over olivine regarding tar/CH4 catalytic reforming.    In order to significantly reduce the tar/CH4 contents, an internal reformer, referred to as the FreeRef reformer, is developed for in-situ catalytic reforming of tar and CH4 using Ni-catalyst in an environment of good gas-solids contact at high temperature.  A study on the internal reformer filled with and without Ni-catalytic pellets was carried out by evaluation of the syngas composition and tar/CH4 content. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases from 25 g/m3 down to 5 g/m3 and the CH4 content from 11% down below 6% in the syngas.   The MIUN gasifier has a unique design suitable for in-bed tar/CH4 catalytic reforming and continuously internal regeneration of the reactive bed material. The novel design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas composition. / Gasification-based Biorefinery for Mechanical Pulp Mills

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed 1/24/2008). Includes bibliographical references.

Thesis (M.S.); Submitted to Central Missouri State University, Warrensburg, MO (US); 17 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. Kerr, Kent. NNSA Kansas City Site Office (US) NNSA Kansas City Site Office. 12/17/2004. Report is also available in paper and microfiche from NTIS.

Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry, Durban University of Technology, Durban, South Africa, 2015. / Fossil fuel reserves have been diminishing worldwide thus making them very scarce in the long term. These fuel sources and their by-products which are used commercially tend to produce large quantities of emissions. Some of them are believed to be toxic to flora and fauna. It is primarily for this reason that researchers worldwide have begun to seek out alternative sources of environmentally safe fuel. Biodiesel from algae is one of these sources that have been examined over the last few decades. Biodiesel has been produced from other plant-based material and waste oils in countries like America and Japan. However, the use of food based crops for biodiesel production has been challenged as it has an impact on food production on an international scale. Algae have only recently been investigated for their feasibility for biodiesel production on a large scale. The aim of this study was to investigate and develop technologies for biodiesel production from algae. The species of algae chosen were chlorella sp and scenedesmus sp., since they are indigeneous to Kwazulu Natal in South Africa. Samples were obtained from a local raceway pond and prepared for analysis. Drying protocols used freeze, oven and sun drying for initial preparation of the samples for analysis. Sun drying was the least energy intensive but most time consuming. At laboratory scale, oven drying was chosen as the best alternative. Lipid extraction methods investigated were the separating funnel method, the soxhlet method, microwave assisted extraction (MAE) and the expeller press. Thirteen solvents covering a range of polarities were used with the extraction methods to determine the efficiency of the solvent with these methods. Optimization of the MAE method was conducted using both the one factor at a time (OFAT) method and a design of experiment (DOE) statistical method. The shelf life of algal biomass was determined by ageing the samples for approximately three months. Direct and in-situ transesterification of lipid extracts to produce biodiesel was investigated using both acid and base catalysis. Qualitative and quantitative analyses were conducted using Fourier transform infra-red (FTIR) and gas chromatography (GC). Chemical and physical characterization of the biodiesel produced from the algal lipid extracts were compared to both local and international standard specifications for biodiesel. In terms of extraction efficiency, it was found that soxhlet and microwave assisted extraction methods were almost equally good. This was proved by the MAE method yielding an average of 10.0% lipids for chloroform, ethanol and hexane after 30 mL of solvent was used in an extraction time of 10 minutes, while the soxhlet method yielded 10.36% lipids using an extraction volume of 100 mL of solvent with an extraction time of 3 hours. Chloroform, ethanol and hexane were more efficient than the other ten solvents used. This was shown by these three solvents producing lipid quantities between 10% to 11% while all the other solvents produced lipid quantities between 2 and 10 %. The best extraction efficiency was achieved by the binary solvent mixture made up of chloroform and ethanol in a 1:1 ratio. Under the conditions optimized, this solvent ratio yielded a lipid content of 11.76%. The methods chosen and optimized for extraction are very efficient, but the actual cost of production of biodiesel need to be determined. Physical methods like the expeller press are not feasible for extraction of the type of biomass produced unless algae are pelletized to improve extraction. This will impact on the cost of producing biodiesel. The transesterification protocols investigated show that the base catalysis produced biodiesel with a ratio of saturates to unsaturates conducive to a good fuel product. The direct esterification method in this study proved to be better than the in-situ method for biodiesel production. The in-situ method was also more labour intensive. Chromatography was found to be a fast and efficient method for qualitative and quantitative determination of biodiesel. Characterization tests showed that the quality of biodiesel produced was satisfactory. It also showed that the methods used in this study were feasible for the satisfactory production of biodiesel which meets local and international specifications.