Most heavy crude oils underwent biodegradation and generated a significant amount of naphthenic acids. Naphthenic acids are polar compounds with the carboxylic group and are considered as a major factor affecting the ...Most heavy crude oils underwent biodegradation and generated a significant amount of naphthenic acids. Naphthenic acids are polar compounds with the carboxylic group and are considered as a major factor affecting the oil viscosity. However, the relationship between the molecular composition of naphthenic acids and oil viscosity is not well understood. This study examined a “clean” heavy oil with low contents of heteroatoms but had a high content of naphthenic acids. Naphthenic acids were fractionated by distillation and caustic extraction. The molecular composition was characterized by high-resolution Orbitrap mass spectrometry. It was found that the 2- and 3-ring naphthenic monoacids with 15–35 carbon atoms are dominant components of the acid fractions;the caustic extraction is capable of isolating naphthenic acids with less than 35 carbons, which is equivalent to the upper limit of the distillable components, but not those in the residue fraction;the total acid number of the heavy distillates is higher than that of the residue fraction;the viscosity of the distillation fraction increases exponentially with an increased boiling point of the distillates. Blending experiments indicates that there is a strong correlation between the oil viscosity and acids content, although the acid content is only a few percent of the total oil.展开更多
Clay such as kaolinite, is commonly used as an additive to modify the thermal properties of polymer. In this paper, the morphology, composition, shape and structure of kaolinite was characterized by various advanced t...Clay such as kaolinite, is commonly used as an additive to modify the thermal properties of polymer. In this paper, the morphology, composition, shape and structure of kaolinite was characterized by various advanced techniques. The TEM/ EDX data showed that the kaolinite had a larger particle size and a Si/Al ratio of 1.8. The individual particle of kaolinite was a single crystalline. TEM also showed that these particles were always stacked together due to the presence of electrostatic cohesive energy and hydrogen bond between plaletes. The PAS FTIR spectra showed that no absorbance of hydroxyl group for hydration water in hydrogen bond region or at 1650cm- 1 was observed at room temperature. It meant a little ability to adsorb water for kaolinite particle. Kaolinite clay also showed no change for its PAS FTIR spectra with increasing temperature. The TGA results revealed that kaolinite almost doesn′ t lose weight at 60℃ due to loss of dehydration of absorbed water, however, it will decomposed around 510℃ and lose its hydroxyl functional group in the form of water (dehydroxylation). The result is consistent with that of PAS FTIR analysis. This suggests that the structural hydroxyl group on the surface of individual kaolinite clay particle is very stable below 500℃ , and the kaolinite composed polymer could be got by the reaction of its stable structural hydroxyl group with isocynate group of polyurethane prepolymer.展开更多
A Canadian in situ oilsands bitumen-derived vacuum residue(VR)was subjected to supercritical fluid extraction and fractionation(SFEF)into 13 extractable fractions and an unextractable end-cut and characterized by posi...A Canadian in situ oilsands bitumen-derived vacuum residue(VR)was subjected to supercritical fluid extraction and fractionation(SFEF)into 13 extractable fractions and an unextractable end-cut and characterized by positive-and negative-ion electrospray ionization(ESI)Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).The results of negative-ion ESI FT-ICR MS showed that the N1 class species was the most abundant and the multifunctional group compounds,such as N1 O1,N1 O2,N1 S1,N1 S2,and N2 class species became abundant as the SFEF fraction became heavier.In positive-ion ESI mode,the relative abundance of N1 class species decreased gradually in the heavy SFEF fractions while that of multifunctional group compounds increased.The relative abundance of N4 V1 O1 increased dramatically in heavy fractions and the end-cut.The distributions of polar heteroatom species of VR derived from oilsands bitumen were similar with those of VR derived from the Venezuela Orinoco extra heavy oil.展开更多
基金supported by the National Key R&D Program of China(2018YFA0702400)Science Foundation of China University of Petroleum,Beijing(ZX20210029).
文摘Most heavy crude oils underwent biodegradation and generated a significant amount of naphthenic acids. Naphthenic acids are polar compounds with the carboxylic group and are considered as a major factor affecting the oil viscosity. However, the relationship between the molecular composition of naphthenic acids and oil viscosity is not well understood. This study examined a “clean” heavy oil with low contents of heteroatoms but had a high content of naphthenic acids. Naphthenic acids were fractionated by distillation and caustic extraction. The molecular composition was characterized by high-resolution Orbitrap mass spectrometry. It was found that the 2- and 3-ring naphthenic monoacids with 15–35 carbon atoms are dominant components of the acid fractions;the caustic extraction is capable of isolating naphthenic acids with less than 35 carbons, which is equivalent to the upper limit of the distillable components, but not those in the residue fraction;the total acid number of the heavy distillates is higher than that of the residue fraction;the viscosity of the distillation fraction increases exponentially with an increased boiling point of the distillates. Blending experiments indicates that there is a strong correlation between the oil viscosity and acids content, although the acid content is only a few percent of the total oil.
文摘Clay such as kaolinite, is commonly used as an additive to modify the thermal properties of polymer. In this paper, the morphology, composition, shape and structure of kaolinite was characterized by various advanced techniques. The TEM/ EDX data showed that the kaolinite had a larger particle size and a Si/Al ratio of 1.8. The individual particle of kaolinite was a single crystalline. TEM also showed that these particles were always stacked together due to the presence of electrostatic cohesive energy and hydrogen bond between plaletes. The PAS FTIR spectra showed that no absorbance of hydroxyl group for hydration water in hydrogen bond region or at 1650cm- 1 was observed at room temperature. It meant a little ability to adsorb water for kaolinite particle. Kaolinite clay also showed no change for its PAS FTIR spectra with increasing temperature. The TGA results revealed that kaolinite almost doesn′ t lose weight at 60℃ due to loss of dehydration of absorbed water, however, it will decomposed around 510℃ and lose its hydroxyl functional group in the form of water (dehydroxylation). The result is consistent with that of PAS FTIR analysis. This suggests that the structural hydroxyl group on the surface of individual kaolinite clay particle is very stable below 500℃ , and the kaolinite composed polymer could be got by the reaction of its stable structural hydroxyl group with isocynate group of polyurethane prepolymer.
文摘A Canadian in situ oilsands bitumen-derived vacuum residue(VR)was subjected to supercritical fluid extraction and fractionation(SFEF)into 13 extractable fractions and an unextractable end-cut and characterized by positive-and negative-ion electrospray ionization(ESI)Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).The results of negative-ion ESI FT-ICR MS showed that the N1 class species was the most abundant and the multifunctional group compounds,such as N1 O1,N1 O2,N1 S1,N1 S2,and N2 class species became abundant as the SFEF fraction became heavier.In positive-ion ESI mode,the relative abundance of N1 class species decreased gradually in the heavy SFEF fractions while that of multifunctional group compounds increased.The relative abundance of N4 V1 O1 increased dramatically in heavy fractions and the end-cut.The distributions of polar heteroatom species of VR derived from oilsands bitumen were similar with those of VR derived from the Venezuela Orinoco extra heavy oil.
