The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Ludovic Duponchel - One of the best experts on this subject based on the ideXlab platform.
-
Chemometric Exploration of APPI(+)-FT-ICR MS Data Sets for a Comprehensive Study of Aromatic Sulfur Compounds in Gas Oils
Analytical Chemistry, 2019Co-Authors: Julie Guillemant, Florian Albrieux, Marion Lacoue-nègre, Luis Pereira De Oliveira, Jean-francois Joly, Ludovic DuponchelAbstract:Sulfur content in gas oils is strictly regulated by legal specifications for environmental reasons. Gas oils are composed of various aromatic sulfur compounds and some of them are known to be very refractory for the sulfur removal reactions. Thus, an accurate analysis of the sulfur compounds is important to find the appropriate operating conditions of the gas oil hydrotreating processes. Aromatic sulfur compounds contained in 23 gas oils samples were analyzed using APPI(+)-FT-ICR MS considering six replicates. Significant differences were spotted within several processed gas oils. A comparison of one feed and its corresponding effluents also confirmed the well-known refractory character of sulfur compounds such as poly alkylated Dibenzothiophenes. To go deeper in the molecular exploration, chemometric tools were applied on this spectral dataset including Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). A unique data rearrangement was performed directly inspired on DBE vs carbon number plots that are systematically used in petroleomics studies. Then, these chemometric tools provided a successful classification of each type of gas oils. The PCA model has been also validated on mixed blends allowing us to conclude that it could be applied to unknown samples in order to identify the process used to produce them. Moreover, the exploration of the generated loadings revealed key types of molecules driving the classification such as C3-DBT which is a dibenzothiophene core with three additional carbon atoms. Indeed, it is known to remain mainly in deeply hydrotreated samples, validating previous observations regarding its potential refractory character. The ability of chemometric tools to extract specific molecular information from ultra-high resolution MS spectra reveals its huge potential for an exhaustive study of highly complex mixtures such as crude oils.
Zbigniew Ring - One of the best experts on this subject based on the ideXlab platform.
-
Structure-HDS Reactivity Relationship of Dibenzothiophenes Based on Density Functional Theory
Catalysis Letters, 2004Co-Authors: Hong Yang, Craig Fairbridge, Jinwen Chen, Zbigniew RingAbstract:Perpendicular adsorption of alkyl-substituted Dibenzothiophenes on a Mo10S18cluster was studied using density functional theory. The Mayer bond order between the sulfur atom of dibenzothiophene and the molybdenum atom of the Mo10S18cluster was calculated from the optimized adsorption complex. Depending on the position of the alkyl substitution in dibenzothiophene, the values of the Mayer bond order were classified into three groups, and compared with the experimental hydrodesulfurization (HDS) rate constants measured at 320 °C, 70 atm, and 1. 6 h-1over a NiMo/Al2O3catalyst using a light cycle oil.
-
Inhibition of nitrogen compounds on the hydrodesulfurization of substituted Dibenzothiophenes in light cycle oil
Fuel Processing Technology, 2004Co-Authors: Hong Yang, Craig Fairbridge, Jinwen Chen, Yevgenia Briker, Yu Jie Zhu, Zbigniew RingAbstract:The influence of nitrogen compounds on the hydrodesulfurization (HDS) activities of a series of substituted Dibenzothiophenes in light cycle oil (LCO) was studied over a NiMo/Al2O3 commercial catalyst. Three types of light cycle oil with nitrogen compounds of different concentrations and chemical natures were used as feed—an original fluid catalytic cracking light cycle oil (LCO), LCO with most of its basic nitrogen removed, and an ultra-low nitrogen LCO. Experiments were conducted in a fixed-bed microreactor at a total pressure of 70 atm, temperatures between 330 and 400 °C, and liquid hourly space velocities (LHSV) in the range of 1.0 to 3.5 h−1. The inhibition effects of nitrogen compounds on the HDS reactivity of the three sulfur groups—total sulfur, hard sulfur, easy sulfur—and 14 specific mono-, di- and tri-alkyl substituted Dibenzothiophenes were investigated. The results showed that the HDS rate significantly increased using ultra-low nitrogen LCO. Pseudo first-order rate constants were estimated for the 14 mono-, di- and tri-alkyl substituted Dibenzothiophenes. The HDS rates could be classified into three groups based on the position of the substituents. It was found that 4 and 6 substituted Dibenzothiophenes had the lowest HDS rates. The HDS rate of the 14 substituted Dibenzothiophenes were all increased when the ultra-low nitrogen feed was used. The improvement was greater for 4 and 6 substituted Dibenzothiophenes than for those with one of the substituents at either the 4 or 6 positions. This finding indicates that the hydrogenation route is more strongly suppressed than hydrogenolysis route by nitrogen compounds since the hydrogenation route is believed to be the predominant reaction pathway for 4 and 6 alkyl-substituted Dibenzothiophenes.
-
Adsorption of Dibenzothiophene Derivatives over a MoS2 NanoclusterA Density Functional Theory Study of Structure−Reactivity Relations
Energy & Fuels, 2003Co-Authors: Hong Yang, Craig Fairbridge, Zbigniew RingAbstract:Various adsorption configurations of dibenzothiophene, a series of one and two methyl-substituted Dibenzothiophenes and their hydrogenated derivatives on a MoS2 nanocluster, were studied using self-consistent density functional theory with generalized-gradient approximation. The objective was to explore the relationship between the structure and catalytic hydrodesulfurization reactivity of these sulfur molecules. The calculated adsorption energies indicated that flat adsorption was more energetically favorable over perpendicular adsorption, due to the interactions of the sulfur atom, the thiophene, and aromatic rings of the sulfur molecule with the molybdenum atoms on the catalyst surface. The adsorption energy in the flat adsorption mode decreased when the aromatic ring was saturated, while the adsorption energy in the perpendicular mode increased with progressive saturation of the Dibenzothiophenes. In the flat adsorption mode, dibenzothiophene, 4-methyldibenzothiophene, 2,8-, 3,7-, and 4,6-dimethyldibe...
-
oxidation reactivities of Dibenzothiophenes in polyoxometalate h2o2 and formic acid h2o2 systems
Applied Catalysis A-general, 2001Co-Authors: Craig Fairbridge, Zbigniew RingAbstract:Abstract Dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene are typical thiophenic sulfur compounds that exist in diesel fuels. Using toluene solutions of the model compounds, experiments were carried out to compare the reactivity of the different Dibenzothiophenes in oxidation reactions, a key step for oxidative desulfurizations. A series of polyoxometalate/H 2 O 2 systems were evaluated for dibenzothiophene oxidation. The H 2 O 2 solutions of phosphotungstic acid and its salt were very active catalyst systems for the model compound oxidation, while their molybdenum counterpart systems were much less active. The H 2 O 2 solutions of silicotungstic and silicomolybdic compounds were the least active catalyst systems for the reaction. Oxidation reactivities decreased in the order of dibenzothiophene>4-methyldibenzothiophene>4,6-dimethyldibenzothiophene, the same reactivity trend that exists in HDS. However, the oxidation of the Dibenzothiophenes was achieved under mild reaction conditions and it was easy to increase reaction temperature or reaction time to achieve high oxidation conversions, even for the least reactive 4,6-dimethyldibenzothiophene. Apparent activation energies of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene oxidation were 53.8, 56.0, and 58.7 kJ/mol, respectively. These activation energies indicated a decrease in reactivity of Dibenzothiophenes as methyl substitutes increased at the 4 and 6 positions on dibenzothiophene rings. Interestingly, in a formic acid/H 2 O 2 system, the oxidation reactivity of the Dibenzothiophenes showed the reverse trend, suggesting that steric hindrance might play a role when bulky polyoxoperoxo species, which likely form in a hydrogen peroxide solution, act as catalysts.
Julie Guillemant - One of the best experts on this subject based on the ideXlab platform.
-
Chemometric Exploration of APPI(+)-FT-ICR MS Data Sets for a Comprehensive Study of Aromatic Sulfur Compounds in Gas Oils
Analytical Chemistry, 2019Co-Authors: Julie Guillemant, Florian Albrieux, Marion Lacoue-nègre, Luis Pereira De Oliveira, Jean-francois Joly, Ludovic DuponchelAbstract:Sulfur content in gas oils is strictly regulated by legal specifications for environmental reasons. Gas oils are composed of various aromatic sulfur compounds and some of them are known to be very refractory for the sulfur removal reactions. Thus, an accurate analysis of the sulfur compounds is important to find the appropriate operating conditions of the gas oil hydrotreating processes. Aromatic sulfur compounds contained in 23 gas oils samples were analyzed using APPI(+)-FT-ICR MS considering six replicates. Significant differences were spotted within several processed gas oils. A comparison of one feed and its corresponding effluents also confirmed the well-known refractory character of sulfur compounds such as poly alkylated Dibenzothiophenes. To go deeper in the molecular exploration, chemometric tools were applied on this spectral dataset including Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). A unique data rearrangement was performed directly inspired on DBE vs carbon number plots that are systematically used in petroleomics studies. Then, these chemometric tools provided a successful classification of each type of gas oils. The PCA model has been also validated on mixed blends allowing us to conclude that it could be applied to unknown samples in order to identify the process used to produce them. Moreover, the exploration of the generated loadings revealed key types of molecules driving the classification such as C3-DBT which is a dibenzothiophene core with three additional carbon atoms. Indeed, it is known to remain mainly in deeply hydrotreated samples, validating previous observations regarding its potential refractory character. The ability of chemometric tools to extract specific molecular information from ultra-high resolution MS spectra reveals its huge potential for an exhaustive study of highly complex mixtures such as crude oils.
Hong Yang - One of the best experts on this subject based on the ideXlab platform.
-
Structure-HDS Reactivity Relationship of Dibenzothiophenes Based on Density Functional Theory
Catalysis Letters, 2004Co-Authors: Hong Yang, Craig Fairbridge, Jinwen Chen, Zbigniew RingAbstract:Perpendicular adsorption of alkyl-substituted Dibenzothiophenes on a Mo10S18cluster was studied using density functional theory. The Mayer bond order between the sulfur atom of dibenzothiophene and the molybdenum atom of the Mo10S18cluster was calculated from the optimized adsorption complex. Depending on the position of the alkyl substitution in dibenzothiophene, the values of the Mayer bond order were classified into three groups, and compared with the experimental hydrodesulfurization (HDS) rate constants measured at 320 °C, 70 atm, and 1. 6 h-1over a NiMo/Al2O3catalyst using a light cycle oil.
-
Inhibition of nitrogen compounds on the hydrodesulfurization of substituted Dibenzothiophenes in light cycle oil
Fuel Processing Technology, 2004Co-Authors: Hong Yang, Craig Fairbridge, Jinwen Chen, Yevgenia Briker, Yu Jie Zhu, Zbigniew RingAbstract:The influence of nitrogen compounds on the hydrodesulfurization (HDS) activities of a series of substituted Dibenzothiophenes in light cycle oil (LCO) was studied over a NiMo/Al2O3 commercial catalyst. Three types of light cycle oil with nitrogen compounds of different concentrations and chemical natures were used as feed—an original fluid catalytic cracking light cycle oil (LCO), LCO with most of its basic nitrogen removed, and an ultra-low nitrogen LCO. Experiments were conducted in a fixed-bed microreactor at a total pressure of 70 atm, temperatures between 330 and 400 °C, and liquid hourly space velocities (LHSV) in the range of 1.0 to 3.5 h−1. The inhibition effects of nitrogen compounds on the HDS reactivity of the three sulfur groups—total sulfur, hard sulfur, easy sulfur—and 14 specific mono-, di- and tri-alkyl substituted Dibenzothiophenes were investigated. The results showed that the HDS rate significantly increased using ultra-low nitrogen LCO. Pseudo first-order rate constants were estimated for the 14 mono-, di- and tri-alkyl substituted Dibenzothiophenes. The HDS rates could be classified into three groups based on the position of the substituents. It was found that 4 and 6 substituted Dibenzothiophenes had the lowest HDS rates. The HDS rate of the 14 substituted Dibenzothiophenes were all increased when the ultra-low nitrogen feed was used. The improvement was greater for 4 and 6 substituted Dibenzothiophenes than for those with one of the substituents at either the 4 or 6 positions. This finding indicates that the hydrogenation route is more strongly suppressed than hydrogenolysis route by nitrogen compounds since the hydrogenation route is believed to be the predominant reaction pathway for 4 and 6 alkyl-substituted Dibenzothiophenes.
-
Adsorption of Dibenzothiophene Derivatives over a MoS2 NanoclusterA Density Functional Theory Study of Structure−Reactivity Relations
Energy & Fuels, 2003Co-Authors: Hong Yang, Craig Fairbridge, Zbigniew RingAbstract:Various adsorption configurations of dibenzothiophene, a series of one and two methyl-substituted Dibenzothiophenes and their hydrogenated derivatives on a MoS2 nanocluster, were studied using self-consistent density functional theory with generalized-gradient approximation. The objective was to explore the relationship between the structure and catalytic hydrodesulfurization reactivity of these sulfur molecules. The calculated adsorption energies indicated that flat adsorption was more energetically favorable over perpendicular adsorption, due to the interactions of the sulfur atom, the thiophene, and aromatic rings of the sulfur molecule with the molybdenum atoms on the catalyst surface. The adsorption energy in the flat adsorption mode decreased when the aromatic ring was saturated, while the adsorption energy in the perpendicular mode increased with progressive saturation of the Dibenzothiophenes. In the flat adsorption mode, dibenzothiophene, 4-methyldibenzothiophene, 2,8-, 3,7-, and 4,6-dimethyldibe...
Luis Pereira De Oliveira - One of the best experts on this subject based on the ideXlab platform.
-
Chemometric Exploration of APPI(+)-FT-ICR MS Data Sets for a Comprehensive Study of Aromatic Sulfur Compounds in Gas Oils
Analytical Chemistry, 2019Co-Authors: Julie Guillemant, Florian Albrieux, Marion Lacoue-nègre, Luis Pereira De Oliveira, Jean-francois Joly, Ludovic DuponchelAbstract:Sulfur content in gas oils is strictly regulated by legal specifications for environmental reasons. Gas oils are composed of various aromatic sulfur compounds and some of them are known to be very refractory for the sulfur removal reactions. Thus, an accurate analysis of the sulfur compounds is important to find the appropriate operating conditions of the gas oil hydrotreating processes. Aromatic sulfur compounds contained in 23 gas oils samples were analyzed using APPI(+)-FT-ICR MS considering six replicates. Significant differences were spotted within several processed gas oils. A comparison of one feed and its corresponding effluents also confirmed the well-known refractory character of sulfur compounds such as poly alkylated Dibenzothiophenes. To go deeper in the molecular exploration, chemometric tools were applied on this spectral dataset including Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). A unique data rearrangement was performed directly inspired on DBE vs carbon number plots that are systematically used in petroleomics studies. Then, these chemometric tools provided a successful classification of each type of gas oils. The PCA model has been also validated on mixed blends allowing us to conclude that it could be applied to unknown samples in order to identify the process used to produce them. Moreover, the exploration of the generated loadings revealed key types of molecules driving the classification such as C3-DBT which is a dibenzothiophene core with three additional carbon atoms. Indeed, it is known to remain mainly in deeply hydrotreated samples, validating previous observations regarding its potential refractory character. The ability of chemometric tools to extract specific molecular information from ultra-high resolution MS spectra reveals its huge potential for an exhaustive study of highly complex mixtures such as crude oils.