A novel process for single-pot conversion of biomass to biofuels was developed called the molten salt catalytic pyrolysis (MSCP) method. The proposed single-pot MSCP process proved to be an inherently more efficient and cost-effective methodology for converting lignocellulosic biomass. In this study, several parameters that affect yield of bio-oil were investigated including carrier gas flow rate; pyrolysis temperature; feed particle size; varying types of molten salt and catalysts. Use of molten salt as the reaction medium offered higher liquid yield and experiments containing ZnCl2 showed higher yield than other chloride salts. The highest yield of bio-oil was up to 66% obtained in a ZnCl2-KCl-LiCl ternary molten salt system compared with 32.2% at the same condition without molten salts. In addition, the effect of molten salt on the composition of bio-oil was also studied. It was observed that molten salt narrowed the product distribution of bio-oil with furfural and acetic acid as the only two main components in the liquid with the exception of water. Finally, a thermogravimetric kinetic study on the pyrolysis of biomass in MSCP was conducted.

Cotton-gin trash (CGT) was pyrolyzed at different temperatures and reaction times using an externally-heated batch reactor. The average yields of output products (solid/char, liquid/bio-oil, and gaseous) were determined. The heating value (HV) of CGT was measured to be around 15-16 MJ kg- 1 (6500-7000 Btu lb-1). In the first set of tests, CGT was pyrolyzed at 600, 700, and 800°C and at 30, 45, and 60 min reaction period. The maximum char yield of 40% by weight (wt.%) was determined at 600°C and 30 min settings, however, the HV of char was low and almost similar to the HV of CGT. A maximum gas yield of 40 wt.% was measured at 800°C and 60 min and the highest liquid yield of 30 wt.% was determined at 800°C and 30 min. In the modified pyrolysis test, the effects of temperature (500, 600, 700, and 800°C) on the product yield and other properties were investigated. The experiment was performed using the same reactor purged with nitrogen at a rate of 1000 cm3 min-1. Gas yield increased as temperature was increased while the effect was opposite on char yield. The maximum char yield of 38 wt.% was determined at 500°C and 30 min. The char had the largest fraction in the energy output (70-83%) followed by gas (10-20%) and bio-oil (7- 9%). Maximum gas yield of 35 wt.% was determined at 800°C. The average yield of CO, H2 and total hydrocarbons (THC) generally increased with increased temperature but CO2 production decreased. Methane, ethane, and propane dominated the THC. The bio-oil yield at 600°C was the highest at about 30 wt.% among the temperature settings. The HV of bio-oil was low (2-5 MJ kg-1) due to minimal non-HC compounds and high moisture content (MC). A simple energy balance of the process was performed. The process was considered energy intensive due to the high amount of energy input (6100 kJ) while generating a maximum energy output of only 10%. After disregarding the energy used for preparation and pyrolysis, the energy losses ranged from 30-46% while the energy of the output represent between 55-70% of the input energy from CGT.

A residential micro-cogeneration system based on a Stirling engine unit was modified to operate with wood derived fast pyrolysis liquid (bio-oil)-ethanol blend. A pilot stabilized swirl combustion chamber was designed to replace the original evaporative burner due to bio-oil’s nondistillable nature. This also required modifications of the engine’s control systems. Efficiencies for the bio-oil/ethanol blend were found be higher than those of diesel due to the higher heat loss incurred with diesel. Based on a modified efficiency, which disregarded the heat loss through the combustion chamber, power efficiencies were found to be comparable. The maximum time of operation with the bio-oil/ethanol blend was approximately 97 minutes due to the clogging of the narrow passages. Carbon monoxide emissions were higher for the bio-oil/ethanol blend due to the operation conditions of the combustion chamber. Oxides of nitrogen emissions were also higher for the bio-oil/ethanol blend due to its inherent nitrogen content.

A residential micro-cogeneration system based on a Stirling engine unit was modified to operate with wood derived fast pyrolysis liquid (bio-oil)-ethanol blend. A pilot stabilized swirl combustion chamber was designed to replace the original evaporative burner due to bio-oil’s nondistillable nature. This also required modifications of the engine’s control systems. Efficiencies for the bio-oil/ethanol blend were found be higher than those of diesel due to the higher heat loss incurred with diesel. Based on a modified efficiency, which disregarded the heat loss through the combustion chamber, power efficiencies were found to be comparable. The maximum time of operation with the bio-oil/ethanol blend was approximately 97 minutes due to the clogging of the narrow passages. Carbon monoxide emissions were higher for the bio-oil/ethanol blend due to the operation conditions of the combustion chamber. Oxides of nitrogen emissions were also higher for the bio-oil/ethanol blend due to its inherent nitrogen content.

Distributed mobile conversion facilities using either fast pyrolysis or torrefaction processes can be used to convert forest residues to more energy dense substances (bio-oil, bio-slurry or torrefied wood) that can be transported as feedstock for bio-fuel facilities. All feedstock are suited for gasification, which produces syngas that can be used to synthesise petrol or diesel via Fischer-Tropsch reactions, or produce hydrogen via water gas shift reactions. Alternatively, the bio-oil product of fast pyrolysis may be upgraded to produce petrol and diesel, or can undergo steam reformation to produce hydrogen. Implementing a network of mobile facilities reduces the energy content of forest residues delivered to a bio-fuel facility as mobile facilities use a fraction of the biomass energy content to meet thermal or electrical demands. The total energy delivered by bio-oil, bio-slurry and torrefied wood is 45%, 65% and 87% of the initial forest residue energy content, respectively. However, implementing mobile facilities is economically feasible when large transport distances are required. For an annual harvest of 1.717 million m3 (equivalent to 2000 ODTPD), transport costs are reduced to less than 40% of the total levelised delivered feedstock cost when mobile facilities are implemented; transport costs account for up to 80% of feedstock costs for conventional woodchip delivery. Torrefaction provides the lowest cost pathway of delivering a forest residue resource when using mobile facilities. Cost savings occur against woodchip delivery for annual forest residue harvests above 2.25 million m3 or when transport distances greater than 250 km are required. Important parameters that influence levelised delivered costs of feedstock are transport distances (forest residue spatial density), haul cost factors, thermal and electrical demands of mobile facilities, and initial moisture content of forest residues. Relocating mobile facilities can be optimised for lowest cost delivery as transport distances of raw biomass are reduced. The overall cost of bio-fuel production is determined by the feedstock delivery pathway and also the bio-fuel production process employed. Results show that the minimum cost of petrol and diesel production is 0.86 $ litre-1 when a bio-oil feedstock is upgraded. This corresponds to a 2750 TPD upgrading facility requiring an annual harvest of 4.30 million m3. The minimum cost of hydrogen production is 2.92 $ kg-1, via the gasification of a woodchip feedstock and subsequent water gas shift reactions. This corresponds to a 1100 ODTPD facility and requires an annual harvest of 947,000 m3. The levelised cost of bio-fuel strongly depends on the size of annual harvest required for bio-fuel facilities. There are optimal harvest volumes (bio-fuel facility sizes) for each bio-fuel production route, which yield minimum bio-fuel production costs. These occur as the benefits of economies of scale for larger bio-fuel facilities compete against increasing transport costs for larger harvests. Optimal harvest volumes are larger for bio-fuel production routes that use feedstock sourced from mobile facilities, as mobile facilities reduce total transport requirements. / Graduate / 0791 / drbrown@uvic.ca

Due to security issues in energy supply and environmental concerns, renewable energy production from biomass becomes an increasingly important area of study. Thus, thermal conversion of biomass via pyrolysis and subsequent upgrading procedures were explored, in an attempt to convert an abundant agricultural residue, corn stover, into potential bio-fuels. Pyrolysis of corn stover was carried out at 400, 500 and 600oC and at moderate pressure. Maximum bio-char yield of 37.3 wt.% and liquid product yield of 31.4 wt.% were obtained at 400oC while the gas yield was maximum at 600oC (21.2 wt.%). Bio-char characteristics (energy content, proximate and ultimate analyses) indicated its potential as alternative solid fuel. The bio-oil mainly consisted of phenolic compounds, with significant proportions of aromatic and aliphatic compounds. The gas product has energy content ranging from 10.1 to 21.7 MJ m-3, attributed to significant quantities of methane, hydrogen and carbon dioxide. Mass and energy conversion efficiencies indicated that majority of the mass and energy contained in the feedstock was transferred to the bio-char. Fractional distillation of the bio-oil at atmospheric and reduced pressure yielded approximately 40-45 wt.% heavy distillate (180-250oC) with significantly reduced moisture and total acid number (TAN) and greater energy content. Aromatic compounds and oxygenated compounds were distributed in the light and middle fractions while phenolic compounds were concentrated in the heavy fraction. Finally, hydrotreatment of the bio-oil and the heavy distillate using noble metal catalysts such as ruthenium and palladium on carbon support at 100 bar pressure, 4 hours reaction time and 200o or 300oC showed that ruthenium performed better at the higher temperature (300oC) and was more effective than palladium, giving about 25-26% deoxygenation. The hydrotreated product from the heavy distillate with ruthenium as catalyst at 300oC had the lowest oxygen content and exhibited better product properties (lower moisture, TAN, and highest heating value), and can be a potential feedstock for co-processing with crude oils in existing refineries. Major reactions involved were conversion of phenolics to aromatics and hydrogenation of ketones to alcohols. Results showed that pyrolysis of corn stover and product upgrading produced potentially valuable sources of fuel and chemical feedstock.

O desenvolvimento de tecnologias para geração de hidrogênio no Brasil tem se tornado um fator relevante, pois se trata de uma fonte de combustível limpa que pode ser obtida a partir de diversas matérias-primas renováveis. Entre essas tecnologias pode-se destacar a reforma a vapor do bio-óleo, proveniente da pirólise da biomassa. O bio-óleo consiste em uma mistura complexa de diversos compostos orgânicos oxigenados tais como: aldeídos, ácidos carboxílicos, cetonas, carboidratos, alcoóis, entre outros, sendo o ácido acético um dos compostos majoritários (∼12-15%), o qual pode ser utilizado como molécula modelo do bio-óleo em reações de reforma a vapor. Entretanto, a reforma a vapor do ácido acético apresenta algumas dificuldades, como a formação de coque na superfície dos catalisadores, o que pode resultar na desativação do mesmo. Dentro deste contexto, este trabalho teve como objetivo desenvolver catalisadores a base de níquel (Ni) promovidos com magnésio (Mg) e nióbio (Nb) suportados em alumina (γ-Al2O3), para aplicação na reforma a vapor do ácido acético, visando minimizar e/ou modificar a estrutura dos depósitos carbonáceos, bem como aumentar a atividade e seletividade para o hidrogênio. Para isso, sintetizaram-se inicialmente três catalisadores com diferentes teores de Ni, (10, 15 e 20%), suportados em alumina, sendo que o catalisador com 15% de Ni em massa foi o que apresentou melhor seletividade e atividade para a reforma a vapor do ácido acético. A partir da melhor carga de Ni, adicionaram-se quatro diferentes teores de Mg e Nb 1,0%; 2,5%; 5,0% e 10% em massa. Entre os catalisadores promovidos com Mg, o catalisador com 5,0% de Mg (15%Ni5%Mg/Al), apresentou uma conversão de 96% para o ácido acético, com seletividade para o hidrogênio em torno de 65% a 600 oC. Além disso, este catalisador apresentou menor taxa de formação de coque e menor tamanho de partícula de Ni0, comparado ao catalisador não promovido (15%Ni/Al), evidenciando que a adição de Mg pode prevenir a sinterização das partículas de Ni. Entre os catalisadores promovidos com Nb, o catalisador 15%Ni2,5%Nb/Al apresentou maior seletividade para o hidrogênio (∼73%) a 600o C comparado aos demais. Apesar de ter apresentado um maior tamanho de partícula Ni0, a adição de Nb aumentou a capacidade de decomposição do metano, proveniente da reação de decomposição e metanação do ácido acético, favorecendo a produção de hidrogênio, além de promover a formação de nanoestruturas de carbono. Assim, a adição de promotores catalíticos como os estudados neste trabalho pode contribuir para o aumento na produção de hidrogênio, seja pela redução nos depósitos carbonáceos ou pela modificação das estruturas de carbono formados na superfície dos materiais. / The development of technologies for generating hydrogen in Brazil has become an important factor because it is a source of clean fuel which can be obtained from different renewable raw materials. Among these technologies, the steam reforming of bio-oil from the pyrolysis of biomass can be highlighted. The bio-oil is a complex mixture of different oxygenated organic compounds such as aldehydes, carboxylic acids, ketones, carbohydrates and alcohols with acetic acid being one of the major compounds (∼12-15%), which may be used as a model molecule of bio-oil steam reforming reactions. However, the steam reforming of acetic acid presents some difficulties, such as coke formation on the surface of the catalysts, which may result in its deactivation. Thus, this work aimed to develop catalysts based on nickel (Ni) promoted with magnesium (Mg) and niobia (Nb) supported on alumina (γ-Al2O3), for application in steam reforming of acetic acid in order to minimize the formation of carbonaceous residues, as well as increase the activity and selectivity for hydrogen. For this purpose, initially three catalysts were synthesized with different Ni content, (10, 15 and 20%), and the catalyst with 15% Ni mass showed the best activity and selectivity for the steam reforming of acid acetic acid. From the best Ni loading, was added four different concentrations of Mg and Nb, 1%; 2.5%; 5% and 10% by weight. Among the catalysts promoted with Mg, the catalyst with 5% Mg (15% Ni5% Mg/Al) at a temperature of 600 °C, showed a 96% conversion of acetic acid, with selectivity to hydrogen of around 65 %. In addition, this catalyst showed lower rate of coke formation and lower Ni particle size compared to the non-promoted catalyst (15% Ni/Al), showing that the addition of Mg can prevent sintering of Ni particles. Among the catalysts promoted with Nb, the catalyst 15% Ni 2, 5% Nb/Al showed higher selectivity to hydrogen (∼73%) at 600 °C compared to the others. Despite having a larger particle size, the addition of Nb increased the capacity of decomposition of methane from of the decomposition reaction and methanation of acetic acid favoring the production of hydrogen and promoted the formation of nanostructures. Thus, the addition of catalytic promoters can contribute to the increase in hydrogen production, either by a reduction in carbonaceous deposits or the modification of structures formed on the surface of the materials.

With 220 billion dry tons available, biomass is one of the world’s most abundant energy source; it also could be a reliable energy source. The human population annual rate of production is 275 million tons of plastic waste as of the year 2019, which has to be managed to facilitate circular carbon economy. Pyrolysis of biomass has emerged as an attractive option for converting waste into bioenergy. Because of its high oxygen content, acidity and viscosity, pyrolysis bio-oil is generally a low-quality product that requires upgrading before being used directly as a drop-in fuel and a fuel additive; this upgrade is achieved by co-pyrolysis of biomass with waste polymers. Since polymers are a rich source of hydrogen, pyrolysis vapors are upgrade; the advantage of co-pyrolysis is that a separate hydroprocessing unit becomes unnecessary after process optimization. Machine learning is emerging as a growing field to predict and optimize the energy related processes. The process can be finetuned using the models trained on the existing experimental data. In this research, machine learning models were developed to predict product yields from the co-pyrolysis of biomass and polymers. Data from the literature on co-pyrolysis of lignocellulosic biomass and polymer co-pyrolysis provided a tool to predict these outcomes. Machine learning algorithms were examined and trained with datasets acquired for biochar and bio-oil yields, with cross-validation and hyperparameters to fit the ultimate and proximate analysis of the reactants and physical conditions of the reactions. XGBoost predicted a biochar yield with RMSE of 1.77 and R$^2$ of 0.96, and a dense neural network predicted a bio-oil yield with RMSE 2.6 and R$^2$ of 0.96. Proximate analysis features were a necessary addition to the bio-oil model. SHAP (SHapley Additive exPlanations) analysis for the DNN liquid model found biomass fixed carbon, biomass moisture and biomass volatile matter with 0.11, 0.09, and 0.06 mean absolute SHAP values, respectively. The machine learning models provided a convenient and predictive tool for co-pyrolysis reaction within the range of the model’s errors and training features. These models also offered insight into the development of municipal solid waste pyrolysis in a circular carbon economy.

The objectives of this dissertation’s studies were to determine the effects of different additives on biomass wood pellets’ physical properties and the production energy required to produce each treatment. Chapter II was completed using a pneumatic pelletizer as a small scale test to determine effects of different additives. The pneumatic pelletizer was a good indicator of which additives can be successfully pelletized. The results of this chapter show that using bio-oil can significantly increase calorific value, without significantly decreasing durability and significantly increasing production energy required. Corn starch, in a 4% treatment, was shown to not hinder durability or calorific value significantly, but significantly lower production energy. Biochar was shown to be an additive insignificant in production due to such a low durability. Chapter III is a scaled up pelleting study, which takes additives from Chapter II as well as multiple new additives to determine each one’s effects on the physical properties and production energy effects. The larger scale, Sprout Walden pelletizer gave much different results than that of the pneumatic pelletizer. The results tend to prove beneficial to durability, calorific value, and bulk density with multiple of the treatments. Vegetable oil was a treatment shown to be less beneficial with each increase in additive and would not be recommended in a production setting at such levels. Chapter IV focused on the economic effect of the pellets produced in Chapter III. Equations were made to determine the possible marginal revenue using each of the treatments. The marginal revenue equations take into account the changes in durability and calorific value. Biochar 4%, and vegetable oil at 1% and 2% show that an increase in marginal revenue could be possible with these treatments.

There is a growing need to develop the processes to produce renewable fuels and chemicals due to the economical, political, and environmental concerns associated with the fossil fuels. One of the most promising methods for a small scale conversion of biomass into liquid fuels is fast pyrolysis. The liquid product obtained from the fast pyrolysis of biomass is called pyrolysis oil or bio-oil. It is a complex mixture of more than 300 compounds resulting from the depolymerization of biomass building blocks, cellulose; hemi-cellulose; and lignin. Bio-oils have low heating value, high moisture content, are acidic, contain solid char particles, are incompatible with existing petroleum based fuels, are thermally unstable, and degrade with time. They cannot be used directly in a diesel or a gasoline internal combustion engine. One of the challenges with the bio-oil is that it is unstable and can phase separate when stored for long. Its viscosity and molecular weight increases with time. It is important to identify the factors responsible for the bio-oil instability and to stabilize the bio-oil. The stability analysis of the bio-oil showed that the high molecular weight lignin oligomers in the bio-oil are mainly responsible for the instability of bio-oil. The viscosity increase in the bio-oil was due to two reasons: increase in the average molecular weight and increase in the concentration of high molecular weight oligomers. Char can be removed from the bio-oil by microfiltration using ceramic membranes with pore sizes less than 1 µm. Removal of char does not affect the bio-oil stability but is desired as char can cause difficulty in further processing of the bio-oil. Nanofiltration and low temperature hydrogenation were found to be the promising techniques to stabilize the bio-oil. Bio-oil must be catalytically converted into fuels and chemicals if it is to be used as a feedstock to make renewable fuels and chemicals. The water soluble fraction of bio-oil (WSBO) was found to contain C2 to C6 oxygenated hydrocarbons with various functionalities. In this study we showed that both hydrogen and alkanes can be produced with high yields from WSBO using aqueous phase processing. Hydrogen was produced by aqueous phase reforming over Pt/Al2O3 catalyst. Alkanes were produced by hydrodeoxygenation over Pt/SiO2-Al2O3. Both of these processes were preceded by a low temperature hydrogenation step over Ru/C catalyst. This step was critical to achieve high yields of hydrogen and alkanes. WSBO was also converted to gasoline-range alcohols and C2 to C6 diols with up to 46% carbon yield by a two-stage hydrogenation process over Ru/C catalyst (125 °C) followed by over Pt/C (250 °C) catalyst. Temperature and pressure can be used to tune the product selectivity. The hydroprocessing of bio-oil was followed by zeolite upgrading to produce C6 to C8 aromatic hydrocarbons and C2 to C4 olefins. Up to 70% carbon yield to aromatics and olefins was achieved from the hydrogenated aqueous fraction of bio-oil. The hydroprocessing steps prior to the zeolite upgrading increases the thermal stability of bio-oil as well as the intrinsic hydrogen content. Increasing the thermal stability of bio-oil results in reduced coke yields in zeolite upgrading, whereas, increasing the intrinsic hydrogen content results in more oxygen being removed from bio-oil as H2O than CO and CO2. This results in higher carbon yields to aromatic hydrocarbon and olefins. Integrating hydroprocessing with zeolite upgrading produces a narrow product spectrum and reduces the hydrogen requirement of the process as compared to processes solely based on hydrotreating. Increasing the yield of petrochemical products from biomass therefore requires hydrogen, thus cost of hydrogen dictates the maximum economic potential of the process.