Rozprawy doktorskie na temat „Liquid Fuel Conversion”

Since the oil crisis of 1973 considerable interest has been shown in the production of liquid fuels from alternative sources. In particular processes utilizing coal as the feedstock have received considerable interest. These processes can be divided into direct and indirect liquefaction and pyrolysis. This thesis describes the modelling of indirect coal liquefaction processes for the purpose of performing technical and economic assessment of the production of liquid fuels from coal and lignite, using a variety of gasification and synthesis gas liquefaction technologies. The technologies were modeled on a 'step model' basis where a step is defined as a combination of individual unit operations which together perform a significant function on the process streams, such as a methanol synthesis step or a gasification and physical gas cleaning step. Sample results of the modelling, covering a wide range of gasifiers, liquid synthesis processes and products are presented in this thesis. Due to the large number of combinations of gasifier, liquid synthesis processes, products and economic sensitivity cases, a complete set of results is impractical to present in a single publication. The main results show that methanol is the cheapest fuel to produce from coal followed by fuel alcohol, diesel from the Shell Middle Distillate Synthesis process,gasoline from Mobil Methanol to Gasoline (MTG) process, diesel from the Mobil Methanol Olefins Gasoline Diesel (MOGD) process and finally gasoline from the same process. Some variation in production costs of all the products was shown depending on type of gasifier chosen and feedstock.

Kyoto University (京都大学)
0048
新制・課程博士
博士(エネルギー科学)
甲第10326号
エネ博第62号
新制||エネ||19(附属図書館)
UT51-2003-H747
京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻
(主査)教授 坂 志朗, 教授 塩路 昌宏, 助教授 河本 晴雄
学位規則第4条第1項該当

The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and wood chips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above 700º C, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar (g) for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chosen entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2S which reduced the sulphur content of the gas to less than 5 ppbv. Supported cobalt catalyst (100 grams), were loaded into a single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at < 250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~ 350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.

Climate change is one of the biggest global threats of the 21st century. Fossil fuels constitute by far the most important energy source for transportation and the different governments are starting to take action to promote the use of cleaner fuels. Biomass-derived fuels are a promising alternative for diversifying fuel sources, reducing fossil fuel dependency and abating greenhouse gas emissions. The research interest has quickly shifted from first-generation biofuels, obtained from food commodities, to second-generation biofuels, produced from non-food resources. The subject of this PhD thesis is the production of second-generation biofuels via thermochemical conversion: biomass is first gasified to synthesis gas, a mixture of mainly H2 and CO; synthesis gas can then be catalytically converted to different fuels. This work summarizes six publications, which are focused on the synthesis gas conversion step. Two processes are principally examined in this summary. The first part of the PhD thesis is devoted to the synthesis of ethanol and higher alcohols, which can be used as fuel or fuel additives. The microemulsion technique is applied in the synthesis of molybdenum-based catalysts, achieving a yield enhancement. Methanol cofeeding is also studied as a way of boosting the production of longer alcohols, but a negative effect is obtained: the main outcome of methanol addition is an increase in methane production. The second part of the PhD thesis addresses wax hydroconversion, an essential upgrading step in the production of middle-distillate fuels via Fischer-Tropsch. Bifunctional catalysts consisting of noble metals supported on silica-alumina are considered. The deactivation of a platinum-based catalyst is investigated, sintering and coking being the main causes of decay. A comparison of platinum and palladium as catalyst metal function is also carried out, obtaining a fairly different catalytic performance of the materials in terms of conversion and selectivity, very likely due to dissimilar hydrogenation power of the metals. Finally, a kinetic model based on the Langmuir-Hinshelwood-Hougen-Watson formalism is proposed to describe the hydroconversion reactions, attaining a good fitting of the experimental data.
Klimatförändringarna är ett av de största globala hoten under det tjugoförsta århundradet. Fossila bränslen utgör den helt dominerande energikällan för transporter och många länder börjar stödja användning av renare bränslen. Bränslen baserade på biomassa är ett lovande alternativ för att diversifiera råvarorna, reducera beroendet av fossila råvaror och undvika växthusgaser. Forskningsintresset har snabbt skiftat från första generationens biobränslen som erhölls från mat-råvaror till andra generationens biobränslen producerade från icke ätbara-råvaror. Ämnet för denna doktorsavhandling är produktion av andra generationens biobränslen via termokemisk omvandling. Biomassa förgasas först till syntesgas, en blandning av i huvudsak vätgas och kolmoxid; syntesgasen kan sedan katalytiskt omvandlas till olika bränslen. Detta arbete sammanfattar sex publikationer som fokuserar på steget för syntesgasomvandling. Två processer är i huvudsak undersökta i denna sammanfattning. Den första delen av doktorsavhandlingen ägnas åt syntes av etanol och högre alkoholer som kan användas som bränsle eller bränsletillsatser. Mikroemulsionstekniken har använts vid framställningen av molybden-baserade katalysatorer, vilket gav en höjning av utbytet. Tillsatsen av metanol har också studerats som ett sätt att försöka få en högre koncentration av högre alkoholer, men en negativ effekt erhölls: huvudeffekten av metanoltillsatsen är en ökad metanproduktion. Den andra delen av doktorsavhandlingen handlar om vätebehandling av vaxer som ett viktigt upparbetningssteg vid framställning av mellandestillat från Fischer-Tropsch processen. Bifunktionella katalysatorer som består av ädelmetaller deponerade på silica-alumina valdes. Deaktiveringen av en platinabaserad katalysator undersöktes. Sintring och koksning var huvudorsakerna till deaktiveringen. En jämförelse mellan platina och palladium som funktionella metaller genomfördes också med resultatet att det var en ganska stor skillnad mellan materialens katalytiska egenskaper vilket gav olika omsättning och selektivitet, mycket sannolikt beroende på olika reaktionsmönster hos metallerna vid vätebehandling. Slutligen föreslås en kinetisk modell baserad på en Langmuir-Hinshelwood-Hougen-Watson modell för att beskriva reaktionerna vid vätebehandling. Denna modell ger en god anpassning till experimentella data.
El cambio climático es una de las mayores amenazas del siglo XXI. Los combustibles fósiles constituyen actualmente la fuente de energía más importante para el transporte, por lo que los diferentes gobiernos están empezando a tomar medidas para promover el uso de combustibles más limpios. Los combustibles derivados de biomasa son una alternativa prometedora para diversificar las fuentes de energía, reducir la dependencia de los combustibles fósiles y disminuir las emisiones de efecto invernadero. Los esfuerzos de los investigadores se han dirigido en los últimos años a los biocombustibles de segunda generación, producidos a partir de recursos no alimenticios. El tema de esta tesis de doctorado es la producción de biocombustibles de segunda generación mediante conversión termoquímica: en primer lugar, la biomasa se gasifica y convierte en gas de síntesis, una mezcla formada mayoritariamente por hidrógeno y monóxido de carbono; a continuación, el gas de síntesis puede transformarse en diversos biocombustibles. Este trabajo resume seis publicaciones, centradas en la etapa de conversión del gas de síntesis. Dos procesos se estudian con mayor detalle. En la primera parte de la tesis se investiga la producción de etanol y alcoholes largos, que pueden ser usados como combustible o como aditivos para combustible. La técnica de microemulsión se aplica en la síntesis de catalizadores basados en molibdeno, consiguiendo un incremento del rendimiento. Además, se introduce metanol en el sistema de reacción para intentar aumentar la producción de alcoholes más largos, pero los efectos obtenidos son negativos: la principal consecuencia es el incremento de la producción de metano. La segunda parte de la tesis estudia la hidroconversión de cera, una etapa esencial en la producción de destilados medios mediante Fischer-Tropsch. Los catalizadores estudiados son bifuncionales y consisten en metales nobles soportados en sílice-alúmina. La desactivación de un catalizador de platino se investiga, siendo la sinterización y la coquización las principales causas del problema. El uso de platino y paladio como componente metálico se compara, obteniendo resultados catalíticos bastante diferentes, tanto en conversión como en selectividad, probablemente debido a su diferente capacidad de hidrogenación. Finalmente, se propone un modelo cinético, basado en el formalismo de Langmuir-Hinshelwood-Hougen-Watson, que consigue un ajuste satisfactorio de los datos experimentales.

QC 20160308

This paper will discuss the conversion of gas produced from biomass into liquid fuel through the combination of naturally occurring processes, which occur in landfills and anaerobic digesters, and a gas-to-liquids (GTL) facility. Landfills and anaerobic digesters produce gases (LFG) that can be converted into syngas via a Tri-reforming process and then synthesized into man-made hydrocarbon mixtures using Fischer-Tropsch synthesis. Further processing allows for the separation into liquid hydrocarbon fuels such as diesel and gasoline, as well as other middle distillate fuels. Conversion of landfill gas into liquid fuels increases their energy density, ease of storage, and open market potential as a common “drop in” fuel. These steps not only allow for profitable avenues for landfill operators but potential methods to decrease greenhouse gas emissions. The objective of this paper is to present a preliminary design of an innovative facility which processes contaminated biogases and produces a valuable product. An economic analysis is performed to show feasibility for a facility under base case scenario. A sensitivity analysis is performed to show the effect of different cost scenarios on the breakeven price of fuel produced. Market scenarios are also presented in order to further analyze situations where certain product portions cannot be sold or facility downtime is increased. This facility is then compared to traditional mitigation options, such as flaring and electricity generation, to assess the effect each option has on cost, energy efficiency, and emissions reduction.

The use of biomass as a potential feedstock for the production of liquid hydrocarbon fuels has been under investigation in the last few decades. This paper discusses a preliminary design and a feasibility study of producing liquid hydrocarbon fuels from biomass through a combined biochemical and thermochemical route. The process involves anaerobic digestion (AD) of the biodegradable portion of the biomass to produce methane rich gas. The methane rich biogas stream is purified by removing contaminants and upgraded to liquid hydrocarbon fuel in a gas to liquid facility (GTL) via thermochemical conversion route. The biogas conversion involves two major steps: tri-reforming step to produce syngas (a mixture of CO and H2), and Fischer-Tropsch Synthesis (FTS) step to convert the syngas to a spectrum of hydrocarbons. Separation and upgrading of the produced hydrocarbon mixture allows production of synthetic transportation fuels. AD is ranked as one of the best waste management options as it allows for: energy recovery, nutrient recovery, and reduction in greenhouse gases emission. A detailed process modeling of the process was carried out using ASPEN Plus process design software package. Data for the process was based on literature on AD combined with laboratory results on the biogas to liquid conversion process. The composition of the final liquid hydrocarbon from the ASPEN model has been compared to the composition of commercial diesel fuel, and results have shown good agreement. As a result, the most current commercial diesel prices were used to evaluate the potential revenue from selling the product in the open market. The total capital investment to construct the plant with a capacity of handling 100,000 ton per year of wet biomass is $16.2 million with a potential of producing 2.60 million gallons of diesel. The base case feedstock is corn stover. The annual operating cost to run the plant is estimated to be $8.81 million. An annual revenue from selling the diesel product is estimated to be $14.6 million taking into account a green energy incentive of $3.00/gallon of diesel sold. The net present worth at the end of the plant life is $8.76 million with a discounted cash flow of return of 26.2%. The breakeven cost of diesel is determined to be $4.34/gallon assuming no tipping fees are charged for handling the waste. Sensitivity analyses results concluded that the profitability of the process is most sensitive to variation in diesel selling price. Based on these results, it can be concluded that the process is profitable only if incentives are provided for renewable fuels due to the current low prices of fossil fuels.

CO2 global emissions exceed 30 Giga tonnes (Gt) per year, and the high atmospheric concentrations are detrimental to the environment. In spite of efforts to decrease emissions by sequestration (carbon capture and storage) and repurposing (use in fine chemicals synthesis and oil extraction), more than 98% of CO2 generated is released to the atmosphere. With emissions expected to increase, transforming CO2 to chemicals of high demand could be an alternative to decrease its atmospheric concentration. Transportation fuels represent 26% of the global energy consumption, making it an ideal end product that could match the scale of CO2 generation. The long-term goal of the study is to transform CO2 to liquid fuels closing a synthetic carbon cycle. Synthetic fuels, such as diesel and gasoline, can be produced from syngas (a combination of CO and H2) by Fischer Tropsch synthesis or methanol synthesis, respectively. Methanol can be turned into gasoline by MTO technologies. Technologies to make renewable hydrogen are already in existence, but CO is almost exclusively generated from methane. Due to the high stability of the CO2 molecule, its transformation is very energy intensive. Therefore, the current challenge is developing technologies for the conversion of CO2 to CO with a low energy requirement. The work in this dissertation describes the development of a recyclable, isothermal, low-temperature process for the conversion of CO2 to CO with high selectivity, called Reverse Water Gas Shift Chemical Looping (RWGS-CL). In this process, H2 is used to generate oxygen vacancies in a metal oxide bed. These vacancies then can be re-filled by one O atom from CO2, producing CO. Perovskites (ABO3) were used as the oxide material due to their high oxygen mobility and stability. They were synthesized by the Pechini sol-gel synthesis, and characterized with X-ray diffraction and surface area measurements. Mass spectrometry was used to evaluate the reducibility and re-oxidation abilities of the materials with temperature-programmed reduction and oxidation experiments. Cycles of RWGS-CL were performed in a packed bed reactor to study CO production rates. Different metal compositions on the A and B site of the oxide were tested. In all the studies, La and Sr were used on the A site because their combination is known to enhance oxygen vacancies formation and CO2 adsorption on the perovskites. The RWGS-CL was first demonstrated in a non-isothermal process at 500 °C for the H2-reduction and 850 °C for the CO2 conversion on a Co-based perovskite. This perovskite was too unstable for the H2 treatment. Addition of Fe to the perovskite enhanced its stability, and allowed for an isothermal and recyclable process at 550 °C with high selectivity towards CO. In an effort to decrease the operating temperature, Cu was incorporated to the structure. It was found that Cu addition inhibited CO formation and formed very unstable oxide materials. Preliminary studies show that application of this technology has the potential to significantly reduce CO2 emissions from captured flue gases (i.e. from power plants) or from concentrated CO2 (adsorbed from the atmosphere), while generating a high value chemical. This technology also has possible applications in space explorations, especially in environments like Mars atmosphere, which has high concentrations of atmospheric carbon dioxide.

The conversion of synthesis gas to desirable liquid fuels in gasoline and diesel range in a single reactor process with simultaneous use of FT and cracking catalysts was investigated in this dissertation. Co-based catalyst and ZSM-5 were used as a FT and cracking catalysts, respectively. The structural and textural properties of ZSM-5 were analyzed by XRD, BET and particle size analysis. Following, commercially available FT and cracking catalyst were tested in the newly designed fixed bed dual-zone reactor under 350 psi; syngas with H2/CO ratio in the amount of 2, and flow rate of 70, 100 and 130 smL/min; and 0.5, 1.25 and 2.5 g of ZSM-5. The temperature for the FT Co-based catalyst was maintained constant at 190 °C, whereas, the temperature for the additionally implemented cracking catalyst was varied (250, 300 and 350 °C). The effect of operating reaction conditions such as syngas flow rate, Si/Al molar ratio; temperature and loading of cracking catalyst were investigated. It was shown, that in general, decrease of syngas flow rate, ipso facto increase in residence time, resulted in decrease of gasoline and diesel fuel production, whereas reduction of ZSM-5 loading improved the formation of C5 - C17 paraffins. An enhancement in gasoline and diesel paraffin range formation was also observed with the decrease of cracking temperature. In addition, the effect of variation in operating conditions was evaluated for liquid paraffin production and dominance of chain propagation reactions over cracking and/or isomerizarion reactions with cracking catalyst loading and syngas flow rate was observed. As a consequence, the results employing ZSM-5 showed increased formation of light hydrocarbons and aromatics; and reduction of heavier paraffins production. Finally, the effect of various Si/Al molar ratios in the amount of 50, 80 and 280 were studied in this research. It was found, that the decrease in acidity of ZSM-5 zeolite enhanced the selectivity towards desirable products as well as heavier paraffins, but suppressed the formation of CH4. Furthermore, the isomerization reactions became favored in expense of cracking reactions.

Gasification using entrained flow reactors generates syngas that can be upgraded tochemicals with little gas cleaning. Black liquor (BL) is a by-product from pulping industrythat consists of residual wood constituents and spent pulping chemicals. Currently, it iscombusted to recycle the pulping chemicals and at the same time generate steam and power.Alternatively, BL is one of the most attractive fuels for entrained flow gasification due to thecatalytic activity of alkali compounds inherent in BL, possibility for pressurized feeding andthe shared logistics with the pulping plant. However, the high content of ash in BL is also anenergy penalty. Therefore the efficiency of BL gasification can be improved by co-gasifyingit with more energy rich fuels.The current work investigates the gasification characteristics of BL and pyrolysis oil(PO) blends by means of laboratory experiments. Experiments with varying BL/PO blendingratios were conducted using three different devices. An isothermal thermogravimetric reactorwas used to measure the reactivity of char under varying temperature and gas compositions. Asingle particle reactor was used to investigate the conversion of single droplets when exposedto high temperature reactive gas flow using lean, stoichiometric and rich CH4-air flames.Finally, a drop tube furnace was used to study the effect of temperature, gas composition andparticle size on gas, tar, and gasification residues at high temperature (800-1400 °C).Char reactivity of mixture samples was more than 30 times that of PO and comparableto that of pure BL, thereby indicating that catalytic activity was still very high after theaddition of PO. High temperatures enhanced alkali release in the gas phase; however, theconcentration of alkali left in the particles remained high at any temperature and for anymixing ratio. Additionally the blends showed better carbon conversion than pure BL. Theconversion rate of large particles (500-630μm) was controlled by mass diffusion and completecarbon conversion was never reached even at T =1400 °C. In comparison with pine-wood thatwas used as a reference, BL-based samples showed much lower tar concentrations in thesyngas. The difference was attributed to alkali elements. Remarkably, the addition of PO toBL further promoted tar reforming in the presence of CO2. The addition of PO alsosignificantly increased the yields of CH4 and CO.

Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2020
South Africa currently faces an energy security issue with regards to the country’s rather insignificant petroleum reserves. The Fischer-Tropsch Synthesis process has found great application in converting the reserves available to products of economic value in terms of fuels and chemicals finding the adequate application at Sasol and Petro SA alike. However, in the realisation of the fact that coal is a high pollutant and natural gas reserves at a critical low with Sasol and Petro SA respectively, new innovations have become of critical importance. Solid waste management has become an ever-growing problem world-wide due to rapid urbanization and population growth. South Africa was found to have generated 9 million tons of general waste in 2011 with the Western Cape generating 675 kg/capita/annum. The convention of management has been that of landfilling however, this method is fast becoming insignificant due to the lack of space and detrimental nature to the environment. Considering the energy security issue South Africa is facing, and the global drive of finding alternate sources of fuel with the depletion of fossil fuel, attention has turned to MSW as a sustainable source of energy while remediating its effect on the environment. Thermochemical conversions of Municipal Solid Waste (MSW), this presents an attractive means of harnessing the potential value in this waste stream thus thermochemical conversion poses an attractive means of converting this waste stream into valuable fuel products. In the realisation of the 2 problems of energy security and solid waste disposal, Biomass to Liquid (BTL) technology was found to be the most suitable to tackle these issues. BTL is an established process that uses the thermal conversion of biomass into various liquid fuels products through a series of technologies. MSW is highly heterogeneous which poses a processing challenge, unlike virgin biomass which is normally used in BTL technologies. The study investigated the production of high-quality syngas through an Aspen simulation of thermal gasification which would be suitable for liquid fuels and chemicals via Fischer-Tropsch synthesis to bridge the energy security issue in South Africa. As the study also possesses an environmental facet, it was necessary to assess the pollution load caused by the process of landfilling in terms of Heavy Metals and Radionuclides which will be determined by means of radionuclide analysis and heavy metal analysis. The procedures were accomplished by use of the gamma-ray spectroscopy, High Purity Germanium detector, (HPGe) and Inductively Coupled Plasma Optical Emission Spectrometry, (ICP-OES) methods. The study was conducted by making use of Refuse Derived Fuel (RDF) pellets produced from the MSW. 4 Different binders in form of corn starch, guar-gum starch, waste palm oil and waste engine oil were used in the production of the pellets, thus the effect of this on energy content and thermal degradation behaviour was studied. The energy content of MSW in Cape Town was investigated using a bomb calorimeter and the thermal degradation behaviour was studied using Thermogravimetric Analysis (TGA). The South African Government, through the National Development Plan of South Africa, aims to provide access to the grid and off-grid electrical power to a minimum of 95 % of the population by 2030, of which 20 GW of the required 29 GW required for this needs to come from alternative and renewable energy sources. This study using the MSW from the City of Cape Town Municipality in South Africa shows that the MSW has a calorific value of approximately 19 MJ/kg which is significantly high, meaning that the waste can be directly used as fuel in many applications but more importantly that of electricity generation. The calorific value for the pelletised waste was found to be higher at an average of 23.9 MJ/kg which can be compared with South African coal being 25.1 MJ/kg. Using TGA, 3 distinguishable major mass loss regions were found between temperatures 55 – 265 ℃, 270 – 410 ℃ and 410 – 502 ℃. The total sample reduction was found to be more than 90 % on average which is a reduction of the waste. Heavy metals and Radionuclides (HM and R) are abundant in various types of municipal solid waste, including industrial waste, construction waste, medical waste, and household waste. Products containing HM and R are commonly disposed of in MSW or hazardous waste landfills and dumpsites. Approximately an average of 0.8 to 3 kg per capita per day of MSW is generated by suburban areas in South Africa. This method of managing or processing the waste has fast become inadequate and hence the need for new innovations. This has led to the focus on thermochemical conversion as an alternative. The soil is amongst the most considerable sources of radiation exposure to human beings and the migration for the transfer of radionuclides to the immediate environment. Exposure is a direct result of gamma-ray emissions that are produced by the most common terrestrial radionuclides, which are the member of the 238U and 232Th series and 40K of which concentrations differ with respect to the type of soil and the geology of the area. Environmental pollution by chemicals and heavy metals such as Cd, Ni, Zn, and Pb etc., showed a great increase in recent times due to various industrial operations including that of MSW disposal. All heavy metals at high concentrations have strong toxic effects and are regarded as environmental pollutants. Naturally occurring radionuclides activity was investigated at landfill sites from the City of Cape Town using a Hyper-Pure Germanium (HPGe) detector with appropriate shielding coupled to a Palmtop Multichannel Analyzer. Activity concentrations of the radionuclides 238U, 232Th and 40K were obtained from the activity concentrations of their respective daughter radionuclides. To obtain the overall combined effect in terms of activity concentration from the 3 parent radionuclides, the radium equivalent was calculated and 38.273, 41.019 and 83.007 Bq/Kg were obtained from Bellville, Coastal Park, and Vissershok respectively. Other radiological hazards in terms of Internal and External hazard indices and Representative hazard index were determined and found to be within safe limits. The dose rate in the air at 1m above the ground was determined to obtain a characteristic of the external gamma-ray and was found to be 17.490, 18.609 and 38.667 nGy/y for Bellville, Coastal Park, and Vissershok respectively. The health effects of the radiation in terms of annual effective dose and excess lifetime cancer risk were determined to be 0.031 mSv/y and 0.0961×10-3 which are lower than limits set by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the Nuclear Industry Association of South Africa (NIASA). The gasification part of the study was through process simulation models on ASPEN Plus Process simulation software. This investigation proposes a model of syngas creation from Refuse Derived Fuel (RDF) Pellet gasification with air in a fixed bed reactor. The model (utilizing Aspen Plus process simulation software) is utilized to model the anticipated results of RDF gasification and to give some processes fundamentals concerning syngas generation from RDF gasification. The fixed bed reactors are an updraft fixed bed reactor which can be divided into 3 sections which are drying, pyrolysis and gasification. The model is based on a combination of models that the Aspen Plus simulator provides, representing the three stages of gasification. Thermodynamics package used in the simulation comprised the Non-Random Two-Liquid (NRTL) model. The model works on the principle of Gibbs free energy minimization and was validated with experimental data of MSW gasification found in the literature. The RYield module was combined with the RGibbs module to describe pyrolysis section, while the RGibbs module was used for the gasification section individually. Proximate and ultimate analysis of RDF pellets and operating conditions used in the model are discussed. The sensitivity analysis module of Aspen Plus was used to research the effect of air equivalence ratio, ER and temperature value on the syngas composition, and carbon conversion. The results indicate that higher temperature improves gasification as the composition of H2 and CO increase, as well as carbon conversion until a temperature of 900 ℃ and higher air equivalence ratio increases the carbon conversion while decreasing syngas quality as there is an increase in CO2 and H2. The most suitable binder for the gasification of RDF derived from MSW is maize starch, with the optimal process parameters for the production of syngas being that of temperature at 780 0C and airflow rate of 6 kg/hr which translates into a fuel-to-air feed ratio of about 1:2. Results obtained are in good agreement with the experimentally measured data in the literature.

Mitigation of climate change and energy security are major driving forces for increased biomass utilization. The pulp and paper industry consumes a large proportion of the biomass worldwide including bark, wood residues, and black liquor. Due to the fact that modern mills have established infrastructure for handling and processing biomass, it is possible to lay foundation for future gasification based bio-refineries to poly-produce electricity, chemicals or bio-fuels together with pulp and paper products. There is a potential to export electricity or bio-fuels by improving energy systems of existing chemical pulp mills by integrating gasification technology. The present study investigates bio-fuel alternatives from the dry black liquor gasification (BLG) system with direct causticization and direct methane production from the catalytic hydrothermal gasification (CHG) system. The studied systems are compared with bio-fuel alternatives from the Chemrec BLG system and the improvements in the energy systems of the pulp mill are analyzed. The results are used to identify the efficient route based on system performance indicators e.g. material and energy balances to compare BLG systems and the conventional recovery boiler system, potential biofuel production together with biomass to biofuel conversion efficiency, energy ratios, potential CO2 mitigation combining on-site CO2 reduction using CO2 capture and potential CO2 offsets from biofuel use, and potential motor fuel replacement. The results showed that the dry BLG system for synthetic natural gas (SNG) production offers better integration opportunities with the chemical pulp mill in terms of overall material and energy balances. The biofuel production and conversion efficiency are higher in the CHG system than other studied configurations but at a cost of larger biomass import. The dry BLG system for SNG production achieved high biomass to biofuel efficiency and considerable biofuel production. The energy ratio is significant in the dry BLG (SNG) system with less biomass demand and considerable net steam production in the BLG island. The elimination of the lime kiln in the dry BLG systems resulted in reduced consequences of incremental biomass import and associated CO2 emissions. Hydrogen production in the dry BLG system showed the highest combined CO2 mitigation potential i.e. on-site CO2 capture potential and CO2 offset from biofuel replacing fossil fuel. The results also showed that the motor fuel replacement potential with SNG as compressed natural gas (CNG) replacing gasoline in the transport sector is significantly high in countries with large pulp industry.
QC 20120528

Ce travail de thèse double culture s’inscrit dans le cadre de la Transition Énergétique vers un modèle intégrant les potentiels de production de biogaz. Il est consacré à l’étude de la technologie plasma-catalyse de reformage du méthane en présence du dioxyde de carbone en carburants liquides. Une étude géomatique a été développée afin de réaliser la cartographie des zones agricoles potentiellement productrices de biogaz en France. Les résultats révèlent que la cogénération et l’injection du bio-méthane dans le réseau gazier permettent de valoriser seulement 43% du potentiel total en biogaz issu des déchets agricoles en France. La transformation du biogaz en carburants liquides stockables et transportables, à l’aide d’un dispositif pouvant être installé dans des territoires ruraux éloignés, permettrait de tirer davantage de profit de ce potentiel. Les décharges plasma permettent de développer une réactivité suffisante pour exciter et dissocier les molécules du biogaz dans les conditions requises. Un modèle cinétique a été développé afin de déterminer les paramètres du plasma et l’évolution temporelle des espèces réactives ainsi que les processus de conversion du biogaz. Un procédé de Décharge à Barrière Diélectrique Surfacique a été réalisé pour la transformation de mélange de CH₄ et de CO₂ représentatif du biogaz. Les principaux produits gazeux sont CO, H₂, C₂H₆ et C₂H₄ et les principaux produits liquides, représentant 3% à 8% de la masse de biogaz transformé, sont le méthanol, l’isopropanol, l'éthanol et l'acétaldéhyde. L’efficacité énergétique dépendant des paramètres opératoires et varie entre 2% et 9%. L’Energie Spécifique Injectée est le paramètre le plus influent sur l’efficacité énergétique du procédé ainsi que sur la distribution des produits. L’ajout de la vapeur d'eau, précurseur d’espèces actives telles que : OH, O et O-, apporte une nette amélioration des taux de conversion à un coût énergétique égal à 26 eV/molécule. Nous avons étudié le couplage plasma-catalyse par l’emploi de 12 catalyseurs solides. Nous avons élaboré par le procédé Fluidized Spray Plasma des catalyseurs tels que : X%CuO-Y%ZnO/Al₂O₃, TiO₂/SiO₂ et Ag/TiO₂/SiO₂. Ces catalyseurs, ainsi que des catalyseurs élaborés par d’autres techniques ont été caractérisés et testés dans le réacteur SDBD. Il en ressort que la nature du catalyseur affecte peu la conversion du biogaz mais elle modifie la distribution des produits liquides. La meilleure sélectivité en méthanol a été obtenue en utilisant le Pt/Al₂O₃ (élaboré par voie polyol) puis en utilisant le CuO/Al₂O₃ et le 60%Cu-40%ZnO/Al₂O₃
This double culture thesis, merging geography and physics is achieved in the frame of the Energy Transition towards a model integrating biogas production potentials. It is devoted to the study of plasma-catalysis technology for reforming methane in the presence of carbon dioxide to liquid fuels. A geomatic study has been developed to map agricultural areas potentially producing biogas in France. The results reveal that cogeneration and injection of bio-methane into the gas network allows recovering only 43% of the total biogas potential from agricultural waste in France. The transformation of biogas into storable and transportable liquid fuels, using a device that can be installed in remote rural areas, would make more use of this potential. Plasma discharges allows developing sufficient reactivity to excite and dissociate the molecules of the biogas under the required conditions. A kinetic model has been developed to determine plasma parameters and temporal evolution of reactive species as well as biogas conversion processes. A Surface Dielectric Barrier Discharge (SDBD) process was developed for the transformation of CH₄ and CO₂ mixture representative of the biogas. The main gaseous products are CO, H₂, C₂H₆ and C₂H₄ and the main liquid products, representing 3% to 8% of the transformed biogas mass, are methanol, isopropanol, ethanol and acetaldehyde. The energy efficiency depends on the operating parameters and varies between 2% and 9%. Specific Injected Energy is the most influential parameter on the energy efficiency of the process as well as on products distribution. The addition of water vapor, a precursor of active species such as: OH, O and O-, improves the conversion and allows obtaining energy consumption equal to 26 eV/molecule. Plasma-catalysis was also studied by the use of 12 solid catalysts. The Fluidized Spray Plasma process was used to develop catalysts such as X% CuO-Y% ZnO/Al₂O₃, TiO₂/SiO₂ and Ag/TiO₂/SiO₂ by. These catalysts as well as catalysts made by other techniques have been characterized and tested in the SDBD reactor. The main result is that the nature of the catalyst does not affect the conversion of the biogas but it modifies liquid products composition. The best methanol selectivity was obtained using Pt/Al₂O₃ (made by polyol) followed by CuO/Al₂O₃ and then 60% Cu-40% ZnO/Al₂O₃

碩士
國立臺灣大學
環境工程學研究所
103
Since the decrease of fossil fuel, the development of renewable energy is concerned around the world. In this research, we are going to talk about the method of transforming biomass into bioenergy. The way we use is hydrothermal liquefaction (HTL), one of thermochemical methods. And the impact factors of HTL include reaction time, reaction temperature, heating rate, type of materials, diameter of materials, initial gas in reactor and the type of catalysts. The products of HTL contain acetone soluble solids (BO), water soluble organics (WSO), solid product (SP) and gas product. In my experiments, I want to Fig. out how reaction time, reaction temperature, type of materials and type of catalysts affect the outcomes. The most important product of HTL is BO. And the results of BO show that the used of algae powder (AP) will lead to higher yield of BO and higher BO heating value. Without the adding of catalyst, the yield of BO can be 22.31 wt.％ and the BO heating value is 9184.17 kcal kg-1 high. After adding the catalyst, yield can even reach 24.61 wt.% and the heating value can become 9328.32 kcal kg-1. If replacing AP with bamboo chopsticks (BC), the yield of BO is only 3.83 wt.％ low and the BO heating value is only 7393.35 kcal kg-1. However, the adding of catalyst can lead to a big change of BO yield and heating value of BC HTL results. The BO yield can reach 21.24 wt.% and BO heating value can become 8088.18 kcal kg-1 after catalyst being added. Although the heating value of BO from AP is high, the simulated distillation (SDT) result shows that the property of it is not as good as BO from BC. SDT results indicate that the use of BC and adding of catalyst can improve the property of BO and make it more similar to the liquid fuels we used, like kerosene and heavy oil etc.

The degradation of waste polystyrene sample was carried out in the temperature range of 450-575 ‘c by both thermal degradation and by catalytic degradation using SILICA-ALUMINA as catalyst. It was found that liquid product yield increases with increasing temperature in both thermal as well as catalytic degradation till 550’c , afterwards liquid product yield starts decreasing with increasing temperature. In second stage to find out optimum polystyrene : silica-alumina ratio for maximum liquid product yield , catalytic degradation of polystyrene was carried out at 550’c in various proportion, i.e. 20:1 , 15:1 , 10:1 , 5:1 and 4:1. It was found that liquid product yield increases with increasing the ratio of catalyst upto 5:1 and afterwards increasing the catalyst ratio has resulted in decreasing the amount of liquid product. It was also found that styrene was the main constituents of liquid product ,about 86 % , in thermal degradation of polystyrene at 550’c while in catalytic pyrolysis done in 5:1 ratio at the same temperature has only 41 % styrene in the liquid product obtained. This study indicates that mechanism of degradation depends on the temperature of degradation as well as amount of catalyst used for degradation.

This thesis is concerned with studies on the conversion of syngas to liquid hydrocarbons. A major part of the effort is aimed at synthesising the catalyst and use of it in a speci cally designed high pressure-high temperature reactor to produce liquid hydrocarbons with Fischer-Tropsch synthesis. This study was motivated by two important considerations: (a) The predominant need to produce biomass derived liquid fuels such as gasoline and diesel. (b) Identify the key catalyst properties that influence the hydrocarbon yield and accordingly synthesize catalysts that compare with the data available in the literature. The specific areas of this research are: (i) Produce active, efficient Co based catalysts using different methods and characterise them for Fischer- Tropsch process, (ii) Build a reactor for operations at suitable pressure and temperatures and test the conversion process that involves various catalysts depending on the process used for producing them with the principal control parameter being the residence time and (iii) Examine the overall biomass to liquid fuel conversion and the economics of building such systems at smaller throughputs of particular reference to India (or other developing countries). Based on a review of the literature on catalysts, amongst the two FT active metals, iron and cobalt, the latter was chosen for its high activity (60 - 70% conversion in a single pass) along with high selectivity and stability in the synthesis of linear hydrocarbons. The catalysts were supported on alumina and silica-doped alumina (SDA) catalyst carriers and synthesized by incipient wetness impregnation (IWI) method and combustion synthesis (CS) method. During the course of this study, the functionality of IWI catalysts were compared to that of CS catalysts and also the effect of supports on FT reaction were investigated. Several sets of experiments were conducted with each spanning for a duration of 150 - 160 hours to address the syngas conversion and the liquid fuel generation. The fi rst part of this thesis deals with the synthesis of supported cat- alysts that contain cobalt loading of 20 wt.% (expected range of 15 - 25% from literature), the Co0 crystallite size in the range of 15 - 25 nm, and metal dispersion in the range of 9 - 16%. The selected cobalt loading level was due to the fact that loadings less than 10% results in the formation of surface cobalt aluminates (due to the diffusion of cobalt ions into the rst few layers of aluminate lattice) and at loadings greater than 25 - 30 wt.%, no additional increase in the FT activity is observed. Further, the cobalt crystallite sizes below 6 nm show reduced activity due to larger rates of deactivation and carbide formation and crystallite sizes larger than 50 nm show reduced fraction of active sites available for the FT reaction. The Al2O3 (1 mm diameter spheres, BET surface area = 158 m2/g, pore volume = 0.45 ml/g) supported cobalt catalysts were synthesized using the CS method and compared with the conventionally synthesized IWI catalysts. CS catalysts were synthesized using hexamethylenetetramine (HMT) as the fuel. While the CS catalysts have been developed and used for several industrial reactions, especially environmental catalysts, its use for FT reaction has been limited to a few laboratory scale studies. The major limitation for CS process is the high heat release and the consequential high temperature rise rates, resulting in the evolution of combustion products with uncontrolled explosion, eventually powdering the catalysts and in most cases resulting in the loss of active components. Such vigorous behaviour of CS reaction is distinctly evident for metal loading above 5%. The use of these powdered catalysts in a fixed bed reactor demands either re-pelletizing or re-moulding which is considered very disadvantageous. The two instances in the litera- ture that have reported CS catalysts for FT reactions have metal loadings limited to 15% and exist in powdered form, for use in a slurry type reactor or in micro-channel reactors [Shi et al., 2012, LeViness et al., 2014]. The performance of FT catalysis using CS is limited and unavailable in the open literature. In particular, investigations related to the increase in Co3O4 reduction temperatures and the effect of CS process on the cobalt support interaction and the metal dispersion still need further probing. The CS catalysts used in this thesis have been deposited over Al2O3 support spheres with a metal loading of 20 wt.% and without a ecting the integrity of the support structure using a novel technique. The synthesized catalysts resulted in an average cobalt oxide crystallite size of 7 - 10 nm and metal dispersion ranging from 11 - 13.5%. The X-ray photoelectron spectroscopy and the H2 chemisorption analysis of the synthesized catalysts showed that the CS catalysts display reduced metal support interaction in comparison to the IWI catalysts. Strikingly, the Al2O3 supported CS catalysts reduced at temperatures that are 350 K higher than reduction temperatures of IWI catalysts, a feature not explicit in literature. The high reduction temperatures were associated to the reduction of surface Co2+ ions in the Co2+-Al3+ spinel structure. A further effort was made to synthesize cobalt catalysts directly in a single step without the need for further reduction by employing fuel rich conditions (equivalence ratio ( ) of 1.2 and 1.5). However, the XRD analyses of these catalysts revealed the presence of Co3O4. It was observed that, even under the fuel rich conditions, the redox mixture interacts with the atmospheric oxygen, yielding Co3O4. These catalysts (CS- = 1.2, and CS- = 1.5) were characterised by higher degree of reduction (DOR = 75% and 77% respectively) and higher dispersion (D = 12.8% and 13.2% respectively) compared to the CS catalysts synthesized with unity equivalence ratio (DOR = 69% and D = 11%). The Al2O3 supported CS catalysts resulted in an increased FT activity, as the CO conversion increased from 32% for IWI catalysts to 41% for CS catalysts. Similarly, enhanced CO conversion rates were observed for CS catalysts synthesized with = 1.2 and 1.5, with a highest CO conversion of 61% for CS ( = 1.2) catalysts. Strikingly, the FT product spectrum reported a maximum weight fraction of wax hydrocarbons (C24+), allowing for higher degree of surface polymerization for CS catalysts. The formation of waxes reduced with increasing equivalence ratios. Al2O3 supported cobalt catalysts showed a strong cobalt support interac- tion. The maximum metal dispersion that could be attained was limited to 12 - 13% and the degree of metal reduction extended to a maximum of 77% (CS- = 1.5). In order to further examine the influence of the support material on catalytic activity, cobalt was impregnated into 40 wt.% silica doped alumina supports by IWI and CS method. The earlier literature study that reported investigations on the effect of 30 - 40 wt.% SiO2 doping into Al2O3 supports, revealed a silica enriched surface containing phases of only SiO2 and aluminosilicate. A lower concentration of SiO2 doping (1.5 - 30 wt.%) showed phases of silica, alumina and a minimum concentration of aluminosilicate, while higher concentration of silica doping (>40 wt.%) showed a silica enriched surface [Daniell et al.,2000]. Invariably, the least cobalt support interaction for an Al2O3 characteristic support is bound to occur for 40 wt.% silica doping, due to the maximum concentration of aluminosilicate. Therefore, the second part of this thesis investigates the e ect of 40 wt.% silica doping in alumina support on the properties of the synthesized catalysts and thereupon the FT activity and selectivity. The effect of metal support interaction and its consequent effect on the FT activity and hydro- carbon selectivity were investigated. The XRD spectra of SDA support when compared to -Al2O3 and SiO2 support indicated silica coverage of alumina support, in a way that exposed only minimum fraction of -Al2O3 phase on the support surface. Consequently, the SiO2 doping reduced the formation of cobalt aluminates, resulting in lower metal support interaction as com- pared to cobalt deposited in Al2O3 supports. A 34% increase in the degree of cobalt reduction is observed for SDA-CS catalysts, compared to Al2O3 -CS catalysts. In addition, the fraction of active cobalt sites, as measured by the H2 chemisorption experiments, increases by a margin of 48% for SDA-CS catalysts. A 16% increase in the CO conversion was recorded for SDA-CS catalysts compared to Al2O3 -CS catalysts, with a 12% increase in the C5+ hydrocarbon yield. In the available literature, the e ect of SDA (5% SiO2 in Al2O3 [Jean- Marie et al., 2009]) catalysts on the FT reactions have been only limited to the CO conversion and the C5+ hydrocarbon selectivity. The e ect of these catalysts on the nature of product spectrum was notably lacking. Hence, studies were carried to identify the major components of the FT reaction that are predominantly a function of the catalyst apart from the process conditions employed. The results of the product spectrum of SDA supported cobalt catalysts explicit the formation of middle distillate hydrocarbons (C10- C20) as the primary liquid hydrocarbon product, compared to waxes (C24+) for Al2O3 supported cobalt catalysts. The di erence in the product spectrum for alumina and SDA supported catalysts was attributed to the enhanced surface acidity of the SDA support. NH3-TPD analysis of the SDA support showed a 91% excess surface acidity compared to the Al2O3 support. The SDA surface acidity, which was observed as the summation of Lewis and Bronsted acidity, occurs due to the formation of hydroxyl group formation across aluminium and silica atoms. The aluminosilicate behaviour of SDA support was further supported by the FT-IR spectrum. Also, the SDA sup- ported catalyst displayed higher selectivity to (C2 - C5 hydrocarbons ( 2.4 times higher than Al2O3 supported catalysts) owing to its aluminosilicate structure, rendering it a zeolite like behaviour. The third part of this thesis deals with the overall energy balance and presents an economic assessment of biomass to liquid fuel for an annual con- sumption of a nominal 10000 tonne woody biomass system with an expected liquid hydrocarbon output of 1500 tonnes, a size if found economical would be of great importance to the fi eld. Cost analysis involving a 1000 kg/h steam-oxy biomass gasi cation plant paired with FT plant has been evaluated. The system con guration uses an oxy-steam gasi er, a gas cleaning system, CO2 separation system, a compressor to raise the pressure to 3 MPa and a single-pass FT reactor. Detailed capital cost estimates for each sec- tion involved in the BTL system are set out, on the basis of which future commercial large-scale facilities producing fuel and/or power are evaluated. Several elements of the total system are available as o -the-shelf items and the gasi er itself has originated from long experience of such systems for air- gasi cation at the laboratory (see http://cgpl.iisc.ernet.in). The oxy-steam gasi er operates with an equivalence ratio of 0.1 and a steam to biomass ratio in the range of 0.8 - 1.2. The exit syngas from the gasi er comprises 47% H2, 22% CO, 27% CO2 and 4% CH4 (by volume; H2/CO ratio of 2.1:1). The FT reactor consists of a single casing enclosed multi-tubular reactor maintained at 503 K and 3 MPa. Syngas conversions using the combustion synthesised SDA supported cobalt catalysts were considered for this analysis for varying space velocities (WHSV ranging from 2610 ml/h gcat - 873.3 ml/h gcat. The syncrude (C24+, C6-C12 and aqueous products) are separated and processed in a hydrocracker for conversion into high quality liquid transportation fuel. For a once-through FT reactor con guration, substantial energy exists in the gas phase, which includes C1- C5 hydrocarbons and unconverted syngas; the BTL system was therefore designed such that, the fuel-gas energy is con- verted to electricity using an internal combustion engine, either for in-house electricity consumption of for sale to the grid. The analysis elucidates that the fuel ratio, which is the ratio of mass of the liquid fuel to the mass of the gas phase hydrocarbons (including the unconverted syngas), decreases with a reducing WHSV, a ecting the net electricity cost or the gross electricity units sold to the grid. Furthermore, the analysis shows that a market competitive liquid fuel can be produced with a CO conversion greater than 60%, at a cost ranging from 35 to 40 Rs/litre (0.5 - 0.6 USD/litre). The investment of Rs 45,000/ton of liquid fuel (681 USD/tonne) will have a will have a payback of 3.5 years. These results emphasize that an economically a ordable and environmentally favourable BTL system can be produced even at the levels discussed here.

碩士
國立臺灣大學
環境工程學研究所
103
Along with ther rapid development, the demand of fossil fuels such as oil is increases greatly, resulting in a gradual shortage of fossil fuel reserves.Therefore, the exploitation of renewable energies such as bio-energies becomes increasingly important and this issue is indispensable. Among them, biomass has attracted wide attention because of its high availability. Moreover, if the resource comes from waste, then its potential for producing the bio-energy would increase but also the reuse of yield of waste biomass not only reduces the need of raw biomass and serves a way to the bio-fuel. Further, the biomass is mainly made of cellulose and lignin. It can used to produce bio-ethanol via fermentation. Recently, a newly developed thermal-chemical technology of hydrothermal-liquefaction (HTL). It turns the bio-waste into liquid fuel.The most interesting advantage is that the bio-waste doesn’t need to remove the water. It can be directly charged into the reactor to proceed the reaction. It’s very suitable treating for the biomass and algae applies containing water. This research applies to convert waste bamboo chopsticks (WBC) into liquid fuel. Factors examined included temperature (310 and 340 ℃), solvent volume (0, 25, 50, 75, 85, 100% v/v) and catalyst type (homogenous and heterogenous). Properties of products of solid, liquid, gas, and bio-crude oil were analyzed. The results show that the conditions at 340 ℃ with 75 vol.% of isopropanol and 5 wt.% of potassium carbonate have the highest solid conversion (88.09%) and bio-crude oil yield (57.01%). Overall, the enhancing effect of using isopropanol is better than using ethanol. Additional addition of heterogenous catalyst and hydrogen does not offer clear enhancement. Thus, rather than adding hydrogen to the HTL system, a post hydrogenation of the bio-crude oil product of HTL to upgrade its quality may be more feasible. The simulated distillation of bio-crude oil was conducted and compare with those of serveral fuels. The carbon number of bio-crude oil is closed to that JetA-1 aviation fuel , while other properties are not. Further upgrading of bio-crude oil by proper methods, such as hydrogenation and simulated distillation, would be needed to its property of closed to that of JetA-1.The color, viscosity, property of bio-crude oil are closed to those of heavy oil and boat oil.

About 8 tons of dry undigested solid waste is generated by the MixAlco process for every 40 tons of food residue waste fed into the process. This MixAlco process produces liquid fuels and the sludge generated can be further converted into synthesis gas using the process of pyrolysis. The hydrogen component of the product synthesis gas may be separated by pressure swing adsorption and used in the hydrogenation of ketones into fuels and chemicals. The synthesis gas may also be catalytically converted into liquid fuels via the Fischer-Tropsch synthesis process. The auger-type pyrolyzer was operated at a temperature between 630-770 degrees C and at feed rates in the range of 280-374 g/minute. The response surface statistical method was used to obtain the highest syngas composition of 43.9 +/- 3.36 v % H2/33.3 +/- 3.29 v % CO at 740 degrees C. The CH4 concentration was 20.3 +/- 2.99 v %. For every ton of sludge pyrolyzed, 5,990 g H2 (719.3 MJ), 65,000 g CO (660 MJ) and 21,170 g CH4 (1055.4 MJ) were projected to be produced at optimum condition. At all temperatures, the sum of the energies of the products was greater than the electrical energy needed to sustain the process, making it energy neutral. To generate internal H2 for the MixAlco process, a method was developed to efficiently separate H2 using pressure swing adsorption (PSA) from the synthesis gas, with activated carbon and molecular sieve 5A as adsorbents. The H2 can be used to hydrogenate ketones generated from the MixAlco process to more liquid fuels. Breakthrough curves, cycle mass balances and cycle bed productivities (CBP) were used to determine the maximum hydrogen CBP using different adsorbent amounts at a synthesis gas feed rate of 10 standard lpm and pressure of 118 atm. A 99.9 % H2 purity was obtained. After a maximum CBP of 66 % was obtained further increases in % recovery led to a decrease in CBP. The synthesis gas can also be catalytically converted into liquid fuels by the Fischer-Tropsch synthesis (FTS) process. A Co-SiO2/Mo-Pd-Pt-ZSM-5 catalyst with a metal-metal-acid functionality was synthesized with the aim of increasing the selectivity of JP-8 (C10-C17) fuel range. The specific surface areas of the two catalysts were characterized using the BET technique. The electron probe microanalyzer (with WDS and EDS capabilities) was then used to confirm the presence of the applied metals Co, Mo, Pd and Pt on the respective supports. In addition to the gasoline (C4-C12) also produced, the synthesis gas H2:CO ratio was also adjusted to 1.90 for optimum cobalt performance in an enhanced FTS process. At 10 atm (150 psig) and 250 degrees C, the conventional FTS catalyst Co-SiO2 produced fuels rich in hydrocarbons within the gasoline carbon number range. At the same conditions the Co-SiO2-Mo-Pd-Pt/HZSM-5 catalyst increased the selectivity of JP-8. When Co-SiO2/Mo-Pd-Pt-HZSM-5 was used at 13.6 atm (200 psig) and 250 degrees C, a further increase in the selectivity of JP-8 and to some extent diesel was observed. The relative amounts of olefins and n-paraffins decreased with the products distribution shifting more towards the production of isomers.

The present work involves the experimental studies for the production of liquid fuel by thermal and catalytic pyrolysis of waste high-density polyethylene in a laboratory batch reactor. Thermal pyrolysis of virgin HDPE was performed at a temperature range from 400 °C to 550 °C and heating rate of 20 °C/min. The liquid yield is highest 50 wt. % at temperature 450 ºC. Reaction time decreases with increase in temperature. Maximum oil yield in thermal pyrolysis of waste HDPE was 50.8 wt. % at optimum condition of temperature,which is improved to 58.8 wt. %, in kaolin catalyzed degradation under optimum condition of temperature and feed ratio. The rate of reaction, oil yield and quality of oil obtained in the catalytic pyrolysis are significantly improved as compared to thermal pyrolysis.The catalytic activity of kaolin is further enhanced by treating it with four different acids and one base (acetic acid, phosphoric acid, nitric acid, hydrochloric acid and sodium hydroxide). Acid treatment increased the surface area, acidity and also alters the pore volume distribution of kaolin, which support the cracking reaction. The maximum yield of oil in the acid treated kaolin catalyzed pyrolysis of waste HDPE was 79% under optimum conditions. The composition of the oil was analyzed by FTIR and GC-MS. The oil obtained from the catalytic pyrolysis of waste HDPE mostly contains aliphatic hydrocarbons. The fuel properties of the oil obtained from the catalytic pyrolysis of waste HDPE is similar with that of petro-fuels. So they can directly be used as an engine fuel after fractionation or as a feedstock to petroleum refineries.Response surface methodology (RSM) was used to optimize the catalytic pyrolysis process of waste high-density polyethylene to liquid fuel over modified catalyst. The reaction temperature, acidity of the modified catalysts and mass ratio between modified catalysts to waste high-density polyethylene (HDPE) were chosen as independent variables. Optimum operating conditions of reaction temperature (450 °C), acidity of catalyst (0.341) and catalyst to waste HDPE ratio (1:4) were produced with respect to