Relationship between aromatic hydrogen and aromatic carbon in straight run and converted oils

Jaramillo, Lina M. Yañez; Link, Felix; Klerk, Arno de

doi:10.1016/j.fuel.2022.124414

Cited by 4 publications

(3 citation statements)

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“…The aromatic hydrogen content of the liquid products after thermal conversion (Table ) increased compared with that of the feed. Thermal conversion affects the change in aromatic hydrogen content differently from that of aromatic carbon content, and although there is no fixed relationship between aromatic hydrogen and aromatic carbon content, directionally, an increase in aromatic hydrogen content indicates an increase in aromatic carbon content (a property that was not measured in this study). Consequently, the change in aromatic hydrogen content, as shown in Table , reflects on the chemical environment of hydrogen following hydrogen transfer during thermal conversion but is not necessarily proportional to the increase in aromatic carbon.…”

Section: Resultsmentioning

confidence: 76%

Effect of Pressure on Visbreaking Product Composition and Properties

Nascimento,

de Klerk

2024

Energy Fuels

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Visbreaking is a thermal conversion process employed to decrease the viscosity of residual oils, and cracking occurs mainly in the liquid phase. The impact of pressure on thermal cracking is expected to be minor, yet several observations in the literature indicate that pressure may affect coking, the olefin-to-paraffin ratio, and product composition. In this study, the impact of pressure on coil visbreaking at 400 °C was evaluated in a closed system at a severity sufficient to cause the onset of coking. The products from thermal conversion with initial pressures of 0.5−2.0 MPa (low pressure) differed from those with initial pressures of 2.5−4.0 MPa (high pressure). High pressure suppressed coking, and at comparable vacuum residue conversion, the coke yield was lower at high pressure than at low pressure. Pressure had a minor impact on the distillation profile of the products. Under conditions of controlled space time, pressure did not affect the olefin-to-paraffin ratio, H/C molar ratio, or microcarbon residue. Pressure had an impact on composition-dependent properties, such as the first derivative of density and refractive index with respect to temperature, viscosity, and aromatic hydrogen content. No relationship was found between initial pressure and free radicals, n-pentane insoluble content, and molar element ratios measured in the study.

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Section: Resultsmentioning

confidence: 76%

Effect of Pressure on Visbreaking Product Composition and Properties

Nascimento,

de Klerk

2024

Energy Fuels

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“…The changes in the aromatic carbon content did not follow a similar pattern compared to the changes in the aromatic hydrogen content (compare Table and Table ). This finding is consistent with the literature …”

Section: Resultsmentioning

confidence: 99%

“…At first glance, it appears that the variation in aromatic H decreases as the ERT increases (Figure a). However, when analyzing those data, two factors should be kept in mind: first, a fixed relationship between aromatic content and ERT during thermal treatment is not expected; second, the supposed outliers represented by Group II - B+W+S and Group III - B+S suggest that other variables than ERT (i.e., the presence or absence of solids, water, and solvent) may have influenced the changes in aromatic H content during visbreaking. The latter is further supported by the scattered distribution of variation in aromatic C with respect to ERT (Figure b).…”

Section: Discussionmentioning

confidence: 99%

Visbreaking of Bitumen Froth: Influence of Minerals, Water, and Solvent on the Physicochemical Changes in the Bitumen Phase

Bassane

Klerk

2023

Energy Fuels

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Thermal treatment of oil sand bitumen froth has the goal of not only improving the separation process during froth treatment but also accomplishing bitumen upgrading. There is evidence that both water and minerals have an effect on the physicochemical transformations that take place during the treatment. However, little is known about the nature of these transformations and whether the presence of mineral solids and water can be beneficial. The current study investigated the visbreaking of froth at 400 °C with an average equivalent residence time of 30 min. The froth elements (mineral solids and water) were either separated or maintained in the mixture to assess their effects during visbreaking. Visbreaking was performed in the absence and presence of hydrocarbon solvents (n-hexane and kerosene). Viscosity, density, refractive index, elemental composition, persistent free radical content, and nature of the hydrogen and carbon content were evaluated before and after the treatment. The products from froth visbreaking on a solvent-free bitumen basis had a kinematic viscosity in the range 1–4 × 103 mm2/s at 7.5 °C and a density in the range 990–1000 kg/m3 at 15.6 °C. When visbreaking was performed in the presence of n-hexane, the products had a lower increase in aromatic C, lower viscosity, and lower density on solvent-free basis compared to the products from visbreaking performed in kerosene or without a solvent. The presence of mineral solids and/or water during bitumen visbreaking consistently yielded a bitumen product with numerically higher viscosity and density compared with visbreaking of bitumen alone. Mineral solids and water affected hydrogen transfer reactions during visbreaking, which could be seen in terms of the relative change in the aromatic H and C content in the products. When mineral solids were present, some products were adsorbed on the solids, which also affected the H/C and free radical contents of the liquid product.

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