Hydrothermal Treatment of Bitumen Froth: Impact of Mineral Solids and Water on Bitumen Properties

Self Cite

Following previous evidence that hydrothermal treatment of bitumen froth does not lead to bitumen upgrading at 250 °C and promotes viscosity increase, the current study explores the free radical and cationic reactivity of clay minerals found in bitumen froth in promoting heavier material formation through addition reactions. The current investigation employed α-methylstyrene (AMS) and 1-octene as probe molecules instead of bitumen froth, and their conversion at 250 °C in the presence of clay minerals kaolinite and illite was studied in batch reactors. Thermal conversion of AMS and 1-octene at 250 °C in the absence of minerals was observed to be low. In the presence of clay minerals, not only the conversion of AMS and 1-octene was increased but also reactions such as dimerization of AMS and alkylation of 1-octene and toluene (used as solvents) were mainly promoted, leading to heavier product formation. Double-bond isomerization of 1-octene and cumene formation from AMS was side reactions that were also promoted by the clay minerals. Suppression of mineral-related conversion by pyridine and selectivity to different reaction products that enabled differentiation between free radical and cationic reaction pathways indicated that the mineral-related conversion was predominantly cationic in nature. Using the reactions in the presence of minerals and pyridine as surrogates for alkaline bitumen froth, it was concluded that even under alkaline conditions, minerals could promote heavier material formation through cationic addition.

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Free Radical and Cationic Addition due to Clay Minerals Found in Bitumen Froth at 250 °C Probed with Use of α-Methylstyrene and 1-Octene

Turuga

Klerk

2022

Self Cite

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

Bassane

Klerk

2023

Self Cite

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.

Hydrothermal Treatment of Oilsands Bitumen Froth at 400 °C: Influence of Minerals and Water on Hydrogen Transfer, Cracking, and Addition Reactions

Bassane,

de Klerk

2024

Self Cite

Following prior evidence that water and mineral solids influenced the physicochemical properties of the products derived from the visbreaking of bitumen froth at 400 °C, the present study aimed to explore the effect of water and minerals on the reaction chemistry taking place during the thermal conversion of froth. The current study investigated the relative impact of water and mineral solids on hydrogen transfer, cracking, and addition reactions during the thermal treatment of froth at 400 °C. α-Methylstyrene (AMS) was employed as a probe molecule, and selected chemical species identified in the feed and thermally converted products were monitored. Water had a major effect on suppressing the conversion of AMS, whereas the hindrance of AMS conversion by mineral solids seemed to be minor. Substantial evidence of hydrogen and methyl transfer, hydration, and addition reactions was observed through the formation of specific AMS-derived products. The potential free radical and cationic pathways for the conversion of AMS were evaluated based on the product composition of the different reaction systems. There was an indication that the availability of hydrogen donors also influenced the conversion pathways of AMS. Both water and mineral solids favored the extent of hydrogen transfer during the treatment. However, their specific effect on promoting transfer hydrogenation could not be determined. AMS was not a good probe for cracking under the conditions of this study. Evidence of hydration was observed in the water-containing systems. The presence of water suppressed the formation of addition products, resulting in an overall formation of these products that was half of that observed in the absence of water. The presence of minerals during the treatment seemed to have a minor impact on the selectivity profile of addition products, although it had no apparent influence on the overall formation of these products.