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A kukersite oil shale sample from Estonia was pyrolyzed using a Fischer assay method under N2, N2/steam, CO2 and CO2/steam environments. The thermal behavior of the oil shale sample was also studie...

Oxyfuel combustion can reduce CO2 emissions from fossil fuels. Hence, it is currently being investigated for potential use in oil shale-fired power plants, which currently produce most of Estonia’s electricity. Here, experiments were performed with kukersite oil shale for both oxyfuel and conventional combustion in a 60 kWth circulating fluidized bed combustor. In this paper, we provide data on the ash composition including mineral compositions and heavy metal concentrations. Oxyfuel conditions did not noticeably influence the concentrations of heavy metals in the ash but did have significantly lower amounts of free lime because of inhibition of the carbonate decomposition reactions. The results suggest that oxyfuel combustion would produce no significant problems in terms of the behavior of the ash or the fate of heavy metals contained in the ash.

Equations of state are powerful tools for modeling thermophysical properties; however, so far, these have not been developed for shale oil due to a lack of experimental data. Recently, new experimental data were published on the properties of Kukersite shale oil, and here we present a method for modeling the properties of the gasoline fraction of shale oil using the PC-SAFT equation of state. First, using measured property data, correlations were developed to estimate the composition of narrow-boiling-range Kukersite shale gasoline samples based on the boiling point and density. These correlations, along with several PC-SAFT equations of the states of various classes of compounds, were used to predict the PC-SAFT parameters of aromatic compounds present in unconventional oil-containing oxygen compounds with average boiling points up to 180 °C. Developed PC-SAFT equations of state were applied to calculate the temperature-dependent properties (vapor pressure and density) of shale gasoline. The root mean square percentage error of the residuals was 13.2%. The average absolute relative deviation percentages for all vapor pressure and density data were 16.9 and 1.6%, respectively. The utility of this model was shown by predicting the vapor pressure of various portions of the shale gasoline. The validity of this model could be assessed for oil fractions from different deposits. However, the procedure used here to model shale oil gasoline could also be used as an example to derive and develop similar models for oil samples with different origins.

Oil produced from pyrolysis of Kukersi te oil shale and lignocellulosic biomass both contain significant amounts of phenolic compounds. Here we present new experimental vapor pressure data for two such compounds (4-ethyl-2-methoxyphenol and 5-methylresorcinol) and also for a mixture of phenolic compounds extracted from pyrolysis oil (HoneyolTM). Vapor pressure data was measured by high pressure differential scanning calorimetry (DSC), in accordance with the ASTM E 1782 standard test method. The measurements were conducted in the pressure range from 0.89 kPa to atmospheric pressure. The measured temperature ranges for the vapor pressure were 374.5 to 509.1 K for 4-ethyl-2-methoxyphenol, 428.0 to 565.0 K for HoneyolTM and 429.4 to 565.8 K for 5-methylresorcinol. Density data for 4-ethyl-2-methoxyphenol were also measured at 293.15 to 363.15 K. The experimental vapor pressure and density data for 4-ethyl-2-methoxyphenol were fitted using the PC-SAFT equation of state, and the vapor pressure data for the other compounds was fit using the Antoine equation. Enthalpies of vaporization were also calculated. The properties of these compounds were then compared to literature data for other pure phenolic compounds and mixtures of the phenolic compounds from Kukersite shale oil. This comparison indicates that some pure compounds, such as 4-ethyl-2-methoxyphenol, could be used as model compounds for estimating the properties of the phenolic portion of pyrolysis oil.

In Estonia the significant part of power generation is still based on firing oil shale fuel in thermal power plants despite of the growth of the share of the green energy in recent years. Electricity generation is based on power units utilizing different combustion technologies. A significant part still comprises old units with capacity 185-195 MWe commissioned in early 70s of last century. These pulverized combustion (PC) based units utilize oil shale as a fuel and are operating with subcritical steam parameters, characterizing by relatively low efficiency 26 - 30% (net, LHV based). Due to their low performance, operational issues (intensive fouling of heating surfaces), and remarkable environmental impact, these units were decommissioned or retrofitted with boilers implementing circulating fluidized bed combustion (CFBC) technology in 2004-2005. Implementation of CFBC technology for oil shale combustion significantly reduced both operational issues and environmental impact. With some additional modifications in turbine island allowing to increase rated capacity up to 215 MWe and after increasing steam parameters, the net efficiency of up to 37% was achieved. Consequently, the specific CO2 emissions in the range of 0.99 – 1.05 t/MWhe depending on quality of oil-shale used, was achieved. Recently, the new 300 MWe CFBC based power unit was commissioned. It is operating with subcritical steam parameters: live steam temperature 565 °C and pressure 17 MPa. Net efficiency (LHV based) of that unit is 40 % and specific CO2 emissions up to 0.9 t/MWhe in case of firing only oil shale. In this study the technical viability of retrofitting oil shale based power generation units with CC is described. In the analysis two CC methods were considered: post-combustion (assuming conventional amine process) and oxy-fuel combustion. Among other CC technologies these processes are at the present time characterized by higher technical readiness level, can be applied for existing units with minimal modifications and are applicable for oil shale fuel with it specifics. Besides power generation, Estonia has for almost 100 years of experience in production of shale oil through thermal decomposition of oil shale kerogen in retorts. Currently, solid heat carrier (SHC) method is the main method used for producing shale oil. In this method, direct CO2 emission comes from the preparation of SHC by combustion of solid retorting residue (semi-coke). Mainly two combustion methods are presently applied: lift pipe combustion and CFBC which was recently successfully integrated into shale oil production process. The possibility of utilizing CC technologies in shale oil production units and their technical analysis is described in this study.

Inspite of the increasing focus on reducing carbon dioxide emissions, production of shale oil continues to be economically favorable, and production has even increased in recent years. Producing and handling shale oil requires data on its properties, and to provide this data we have undertaken an extensive project to experimentally measure the properties of Estonian kukersite shale oil. In this article we describe the sample preparation methods and present experimental data on key properties of the shale oil samples. Included is data on the densities, refractive indexes, average boiling points, and molar masses of distillation fractions with narrow boiling ranges. A major component of kukersite shale oil is phenolic compounds, and to investigate their effect on the properties we used extraction to obtain samples with either fewer or more phenols than commonly found in the oil. The effect of composition on the properties is discussed. We also present correlations for calculating one of these properties if two others are known. This article lays the groundwork for future articles which will go into further detail on specific properties of these samples.

7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate (mTBD acetate) is a protic ionic liquid that is being investigated for use in industrial processes, such as for producing textiles from cellulose. To aid in designing such processes, we have measured the densities, viscosities, and thermal conductivities of mTBD acetate and aqueous mixtures containing mTBD acetate. We also investigated how excess amounts of mTBD or acetic acid affect the density, and found that in general an excess of either component decreases the density. However, when no water is present, the sample with excess acetic acid actually has a slightly higher density than when there is an equimolar amount of acid and base. The maximum density occurs when some water is present (around 30–40 mol%). We also modeled the density data using the ePC-SAFT equation of state and provide simple correlations for calculating the viscosity and thermal conductivity of these mixtures.

Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor-liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo [ 4.4.0 ] dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo [4.4.0] dec-5-ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.

Producing valuable transportation fuels from shale oil has long been a goal, but to meet modern environmental regulations significant upgrading is required to remove heteroatoms. The large quantities of sulfur, nitrogen and oxygen in shale oil is one of the major obstacles that limit its use. Unlike petroleum upgrading, where desulfurization is the main process, for shale oils denitrification and deoxygenation are also important. This review compiles and summarizes the extensive research that has been performed on removing sulfur, nitrogen and oxygen from shale oil. By far the most widely researched method has been hydrotreatment, but work done with other methods is also presented.

7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD) has useful catalytic properties and can form an ionic liquid when mixed with an acid. Despite its potential usefulness, no data on its thermodynamic and transport properties are currently available in the literature. Here we present the first reliable public data on the liquid vapor pressure (temperature from 318.23 K to 451.2 K and pressure from 11.1 Pa to 10 000 Pa), liquid compressed density (293.15 K to 473.15 K and 0.092 MPa to 15.788 MPa), liquid isobaric heat capacity (312.48 K to 391.50 K), melting properties, liquid thermal conductivity (299.0 K to 372.9 K), liquid refractive index (293.15 K to 343.15 K), liquid viscosity (290.79 K to 363.00 K), liquid–vapor enthalpy of vaporization (318.23 K to 451.2 K), liquid thermal expansion coefficient (293.15 K to 473.15 K), and liquid isothermal compressibility of mTBD (293.15 K to 473.15). The properties of mTBD were compared with those of other relevant compounds, including 1,5-diazabicyclo(4.3.0)non-5-ene(DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,1,3,3-tetramethylguanidine (TMG). We used the PC-SAFT equation of state to model the thermodynamic properties of mTBD, DBN, DBU, and TMG. The PC-SAFT parameters were optimized using experimental data.

One major sustainable development goal is to produce chemicals and fuels from renewable resources, such as biomass, rather than from fossil fuels. A key part of this development is data on the properties of chemicals that appear in this bio-based supply chain. Many of the chemicals have yet to be studied thoroughly, and data on their properties is lacking. Here, we present new experimental data on the properties of 11 bio-compounds, along with PC-SAFT parameters for modeling their properties. The measured data includes vapor pressures, compressed densities, and refractive indexes. The 11 bio-compounds are tetrahydrofuran, 2-pentanone, furfural, 2-methoxy-4-methylphenol, 2-methylfuran, dihydrolevoglucosenone, cyclopentyl methyl ether, 2-sec-butylphenol, levoglucosenone, γ-valerolactone, and 2,6-dimethoxyphenol.

Although the use of chemometric methods to predict fuel quality properties has received wide attention over the past three decades, as seen from the review included with this article, no studies were found about predicting temperature dependent properties of fuels. Since our research is focused on determining thermodynamic properties, rather than quality properties, taking temperature dependencies into account became even more important. To determine if accurate predictions could be obtained over a range of temperatures, the densities of over 300 fuel samples (mostly narrow boiling range oil fractions, considered here as pseudocomponents) were measured and predicted. An alternative fuel (a phenol-rich oil shale oil) was studied because the property prediction methods developed for conventional petroleum samples often give poor results for this and other alternative fuels. The temperature dependence of density for these fuel samples was modelled using a linear equation based on the density at 20 °C and the slope of the density-temperature relationship. Support vector regression was used to predict these parameters for each sample from its infrared spectrum. Then these parameters were used to predict the densities at other temperatures. Densities spanned the range from 0.713 to 1.088 g/cm 3 , and the root mean squared error of the predicted values was 0.004660 g/cm 3 , which is a relative error of less than 1%. In addition to the experimental portion, a literature review is included, which contains an assessment of the accuracy of chemometric methods for predicting many fuel properties.

This article describes the use of Fourier transform infrared (FT-IR) spectroscopy to quantitatively measure the hydroxyl concentrations among narrow boiling shale oil cuts. Shale oil samples were from an industrial solid heat carrier retort. Reference values were measured by titration and were used to create a partial least squares regression model from FT-IR data. The model had a root mean squared error (RMSE) of 0.44 wt% OH. This method was then used to study the distribution of hydroxyl groups among more than 100 shale oil cuts, which showed that hydroxyl content increased with the average boiling point of the cut up to about 350 °C and then leveled off and decreased.

Many refineries use hydrogen to upgrade heavy fuel feedstocks, and therefore, hydrogen solubility is an important parameter. Shale oil is a fuel for which hydrotreatment is of interest, but no data about its hydrogen solubility can be found in the literature. This article presents experimental data for the hydrogen solubility of two shale oil samples measured at high temperatures and pressures (423 to 527 K and 40 to 140 bar). Experiments were performed using a continuous flow apparatus. Results show that the shale oil had a lower hydrogen solubility than most other fuels, probably due to the high content of polar phenolic compounds in the oil. Removing about 80% of the phenolic compounds increased the hydrogen solubility by approximately 0.1 mol H2/kg oil (which is about 15 to 45%, depending on the solubility). Analysis also showed that current prediction methods used for petroleum and coal liquids cannot reliably be used for predicting the hydrogen solubility of this shale oil and other similar fuels.