Jillian Goldfarb

This investigation demonstrates the feasibility of mitigating the economic and environmental burdens associated with commercialization of oil shale by converting its primary solid waste, semicoke, to an adsorbent material. U.S. White River Mine oil shale was pyrolyzed at 600 °C to produce a semicoke; its activation energy of pyrolysis was calculated using the distributed activation energy model to be 206.9 kJ/mol, similar to other domestic oil shales. This simulated semicoke was chemically… Show more

This investigation demonstrates the feasibility of mitigating the economic and environmental burdens associated with commercialization of oil shale by converting its primary solid waste, semicoke, to an adsorbent material. U.S. White River Mine oil shale was pyrolyzed at 600 °C to produce a semicoke; its activation energy of pyrolysis was calculated using the distributed activation energy model to be 206.9 kJ/mol, similar to other domestic oil shales. This simulated semicoke was chemically activated using HCl, KOH, and a double-activation procedure of either HCl followed by KOH or vice versa. The acid-activation step was considerably more effective in developing the surface area and porous network of the semicoke sorbents, as well as removing carbonate minerals, than KOH. The activation energies of oxidation of the raw, pyrolyzed, and activated samples ranged from 100.5 kJ/mol (raw) to 189.0 kJ/mol (semicoke), with the activated samples between these values. Of the activated samples, HCl + KOH had the lowest overall average oxidation-activation energy, 104.4 kJ/mol, and also had the highest derivative thermogravimetric curve peak, indicating high reactivity. The BET surface area of this sample was 74.3 m2/g. However, in the interest of reducing process steps, the single activation using HCl is likely a more efficient option for byproduct conversion, yielding a BET surface area of 51.7 m2/g, which is considerably higher than that of Class F coal fly ash, at ∼5m2/g, a waste material that is commonly employed as a sorbent. Show less

Debate surrounds biomass co-pyrolysis: can thermal decomposition be modeled as the sum of individ-ual components, or do synergistic reactions promote or hinder devolatilization? Activation energies ofmixtures of starch and cellulose pyrolyzed at 10, 50 and 100 K/min were determined via the distributedactivation energy model. Reaction kinetics suggest that blending may promote devolatilization, seenthrough lower activation energies. Yet, evolved gas analysis shows no evidence of synergism as a… Show more

Debate surrounds biomass co-pyrolysis: can thermal decomposition be modeled as the sum of individ-ual components, or do synergistic reactions promote or hinder devolatilization? Activation energies ofmixtures of starch and cellulose pyrolyzed at 10, 50 and 100 K/min were determined via the distributedactivation energy model. Reaction kinetics suggest that blending may promote devolatilization, seenthrough lower activation energies. Yet, evolved gas analysis shows no evidence of synergism as a resultof blending, at least at lower temperatures. As the percentage of cellulose increases, the temperature atwhich the peak mass loss rate occurs and peak evolved gases emerge are linearly related. As such, there islittle evidence of chemical reaction synergism during the pyrolysis of these two biomass building blocks,but rather synergistic behavior is perhaps a result of the starch physically promoting the devolatilizationof cellulose at lower temperatures when present in larger quantities. Show less

Bringing our society to a carbon-neutral, clean-energy future is an evolutionary process that must combine technological advances with available infrastructure. By co-firing biomass in existing coal-fired power plants, we can utilize standing equipment to increase the share of renewables in energy generation portfolios. This study investigates the pyrolysis behavior of blends of sweet cherry pit stones and a West Virginia coal using thermogravimetric analysis at a heating rate of 100 K/min… Show more

Bringing our society to a carbon-neutral, clean-energy future is an evolutionary process that must combine technological advances with available infrastructure. By co-firing biomass in existing coal-fired power plants, we can utilize standing equipment to increase the share of renewables in energy generation portfolios. This study investigates the pyrolysis behavior of blends of sweet cherry pit stones and a West Virginia coal using thermogravimetric analysis at a heating rate of 100 K/min under nitrogen to determine mass loss rates and global activation energies as a function of blend composition. Derivative thermogravimetric curves show two distinct peaks for the fuel blends at temperatures corresponding to peaks for the pure cherry pits and coal. The peak mass loss rates for blends are higher than predicted using an additive scheme at the lower temperature peak and lower than predicted at the higher temperature peak. Global activation energies determined using a first order Arrhenius equation were higher than predicted by a linear addition scheme at lower temperatures, and lower than predicted at higher temperatures, suggesting that the incorporation of the cherry pit biomass may promote devolatilization of the coal at lower temperatures. Show less

This review details sublimation vapor pressure and thermodynamic data on 85 polycyclic aromatic compounds and heterocycles from the early 1900s through 2012. These data were collected using a variety of vapor pressure measurement techniques, from effusion to gas saturation to inclined-piston manometry. A brief overview of each measurement technique is given; these methods yield reproducible sublimation vapor pressure data for low volatility organic compounds such as polycyclic aromatic… Show more

This review details sublimation vapor pressure and thermodynamic data on 85 polycyclic aromatic compounds and heterocycles from the early 1900s through 2012. These data were collected using a variety of vapor pressure measurement techniques, from effusion to gas saturation to inclined-piston manometry. A brief overview of each measurement technique is given; these methods yield reproducible sublimation vapor pressure data for low volatility organic compounds such as polycyclic aromatic compounds and heterocycles. Several conclusions can be drawn from this literature survey, specifically that there remains a dearth of data on the sublimation thermodynamics (and fusion thermodynamics) of heteroatomic high molecular weight aromatic compounds, inhibiting a holistic understanding of the effect of specific heteroatoms and substituent position on the thermodynamics of these compounds. However, we can clearly see from the data that there are a variety of potential intermolecular interactions at work that generally tend to increase the enthalpy of sublimation and decrease the vapor pressure of a substituted polycyclic aromatic compound/polycyclic heterocycles versus its parent compound. Show less

As an alternative fossil fuel garnering attention in the wake of unstable crude oil prices, oil shale faces several obstacles before its seemingly imminent commercialization. One of the largest environmental stumbling blocks to its widespread use is the primary byproduct of oil extraction processes: semicoke. With the majority of semicoke disposed of in open landfills, this waste stream poses a threat to the environment, and its disposal may well represent a waste of a potentially useable… Show more

As an alternative fossil fuel garnering attention in the wake of unstable crude oil prices, oil shale faces several obstacles before its seemingly imminent commercialization. One of the largest environmental stumbling blocks to its widespread use is the primary byproduct of oil extraction processes: semicoke. With the majority of semicoke disposed of in open landfills, this waste stream poses a threat to the environment, and its disposal may well represent a waste of a potentially useable byproduct. Previous studies show that oil shale from Estonia, China, and the United States, pyrolyzed at 500 and 1000 °C at a rate of 20 °C min–1, yield semicokes with relatively high organic char contents and high surface areas. To determine how shale origin and pyrolysis temperature impact the activation energy of oil shale semicoke combustion, we investigate the oxidation kinetics of oil shale semicokes pyrolyzed at these two temperatures. Activation energies in air are in the range of 108–130 kJ mol–1 for the semicokes pyrolyzed at 500 °C and 147–195 kJ mol–1 for samples pyrolyzed at 1000 °C. Depending on the oil shale pyrolysis temperature and extent of reaction, the semicoke oxidative reaction orders range from 0.55 to 0.72. Show less

Incorporation of torrefied biomass into coal-fired power plants could potentially lower the SOx and net CO2 emissions resulting from electricity generation. However, concerns over lower heating values and slightly higher ash content of torrefied biomass suggest that blending it with coal in industrial boilers may be preferable to complete fuel transition. By studying the oxidation kinetics of coal-torrefied biomass blends in a thermogravimetric analyzer at a heating rate of 100°C/min, we find… Show more

Incorporation of torrefied biomass into coal-fired power plants could potentially lower the SOx and net CO2 emissions resulting from electricity generation. However, concerns over lower heating values and slightly higher ash content of torrefied biomass suggest that blending it with coal in industrial boilers may be preferable to complete fuel transition. By studying the oxidation kinetics of coal-torrefied biomass blends in a thermogravimetric analyzer at a heating rate of 100°C/min, we find an additive nature among the fuels for peak mass loss rates and enthalpies of combustion. The activation energy required to initiate decomposition decreases from 132.6 to 77.6 kJ/mol as the torrefied biomass increases from 0 to 100wt%, with a sharp decrease between 0 and 40wt%. Data suggest that incorporation of torrefied biomass into coal-fired boilers is dependent on the ability to sacrifice heating value for the lower emissions of SOx and net CO2 garnered using bio-coal. Show less

The efficient utilization of biomass as a renewable fuel relies on the identification of readily available fuel sources and an adequate description of their decomposition reactions. Cabbage palm (Sabal palmetto) is one potential local energy source for the Southeastern United States. The kinetics of pyrolysis of three particle size fractions (125–250, 250–300, 300–500 μm) of cabbage palm leaf, stalk and trunk were examined using nonisothermal thermogravimetric analysis with heating rates of 25,… Show more

The efficient utilization of biomass as a renewable fuel relies on the identification of readily available fuel sources and an adequate description of their decomposition reactions. Cabbage palm (Sabal palmetto) is one potential local energy source for the Southeastern United States. The kinetics of pyrolysis of three particle size fractions (125–250, 250–300, 300–500 μm) of cabbage palm leaf, stalk and trunk were examined using nonisothermal thermogravimetric analysis with heating rates of 25, 50 and 100 °C min−1 under constant nitrogen flow. Using the Arrhenius equation to calculate the activation energy and pre-exponential factor, three distinct fractions, corresponding primarily to hemicellulose, cellulose and lignin, were found to decompose over three temperature ranges, each with distinct activation energies. The largest mass loss occurred in the mid-temperature fraction (40–45%); the low temperature region had approximately 30% mass loss and the high temperature region had 15–25% mass loss. Pyrolysis at higher heating rates decreased the activation energy of each palm material, whereas particle size was not correlated with activation energy. For leaf, stalk and trunk, activation energies ranged from 64 to 115, 67 to 152 and 19 to 25 kJ mol−1 for the low, medium, and high temperature range fractions, corresponding to hemicellulose, cellulose and lignin, respectively. Show less

Oil shale, a fine-grained sedimentary rock, contains a proportionally large amount of kerogen, which can be converted into oil by thermal degradation of the compacted rock. The primary byproduct of current oil shale oil extraction processes is semicoke. Its landfill deposition presents a possible threat to the environment and represents a waste of a potentially useable byproduct. In this work, we explore the heavy metal content of oil shale semicoke pyrolyzed at 500 and 1000 °C to better… Show more

Oil shale, a fine-grained sedimentary rock, contains a proportionally large amount of kerogen, which can be converted into oil by thermal degradation of the compacted rock. The primary byproduct of current oil shale oil extraction processes is semicoke. Its landfill deposition presents a possible threat to the environment and represents a waste of a potentially useable byproduct. In this work, we explore the heavy metal content of oil shale semicoke pyrolyzed at 500 and 1000 °C to better understand the risks posed by disposal of oil shale processing waste on the nearby environment, as well as impediments to potential byproduct conversion. The greatest potential obstruction to byproduct conversion and the greatest environmental risk posed by open air disposal of oil shale semicoke is likely due to relatively high arsenic concentrations; using X-ray fluorescence spectroscopy, we find arsenic concentrations in semicoke (pyrolyzed at 500 °C) ranging from 25 ppm for Chinese oil shale from the Huadian mine (class C) to 79 ppm for Green River, Colorado, 50 gallons per ton (GPT) of oil shale. Other heavy metal elements analyzed, including barium, copper, lead, manganese, and iron, are well below the United States Environmental Protection Agency (U.S. EPA) regional screening limits. Show less

Anthracene is a common byproduct of incomplete combustion of fossil fuels and other anthropogenic sources. Its heteroatomic counterparts, including 9-bromoanthracene, 1,5-dibromoanthracene, 9,10-dibromoanthracene, 2-chloroanthracene, 9,10-dichloroanthracene, 9-anthraldehyde, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, and anthraquinone, are formed through various mechanistic pathways during the combustion process. We use a differential scanning calorimeter to measure the melting… Show more

Anthracene is a common byproduct of incomplete combustion of fossil fuels and other anthropogenic sources. Its heteroatomic counterparts, including 9-bromoanthracene, 1,5-dibromoanthracene, 9,10-dibromoanthracene, 2-chloroanthracene, 9,10-dichloroanthracene, 9-anthraldehyde, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, and anthraquinone, are formed through various mechanistic pathways during the combustion process. We use a differential scanning calorimeter to measure the melting points and enthalpies of fusion of these compounds. As expected, we find no correlation between molecular mass and melting point and enthalpy of fusion—rather the type, number and position of the heteroatoms substituted on the parent molecule all influence its fusion thermodynamics. A wide range of melting points is noted for the same substituents(s) at different carbon positions. This suggests that intermolecular forces, such as hydrogen bonding and steric repulsion, are significantly impacted by the position of the substituents on the linear anthracene parent molecular. In addition, different substituents at the same position further suggest that the electronegativity/polarity of a given atom strongly influences the observed fusion behavior. Show less

Co-combustion of locally available biomass in existing coal-fired power plants is an attractive option to increase the share of renewable fuels in the energy market with minimal capital investment. Utilizing existing coal-fired combustion equipment for blends requires knowledge of pyrolysis and combustion characteristics. This study presents thermal evolution profiles (decomposition rates, apparent activation energies and devolatilized compounds) of coal–biomass blends to probe the effect of… Show more

Co-combustion of locally available biomass in existing coal-fired power plants is an attractive option to increase the share of renewable fuels in the energy market with minimal capital investment. Utilizing existing coal-fired combustion equipment for blends requires knowledge of pyrolysis and combustion characteristics. This study presents thermal evolution profiles (decomposition rates, apparent activation energies and devolatilized compounds) of coal–biomass blends to probe the effect of blend ratios on pyrolysis and combustion behavior. The global rate of pyrolysis of Illinois No. 6 coal and brewer's spent grains (BSG) is a function of fuel composition, though analysis of evolved gases suggests the presence of both potential additive and synergistic interactions on a molecular level. For oxidation, a rapid decrease in peak conversion rate is seen as the percentage of BSG increases from 0% to 20%, becoming less pronounced as the percentage of BSG increases above 20%. Show less