Reconstruction of Petroleum Feedstocks by Entropy Maximization. Application to FCC Gasolines

In the petroleum industry, the oil fractions are usually complex mixtures containing several hundreds up to several millions of different chemical species. For this reason, even the most powerful analytical tools do not allow to separate and to identify all the species that are present. Hence, petroleum fractions are currently characterized either by using average macroscopic descriptors (density, elemental analyses, Nuclear Magnetic Resonance, etc.) or by using separative techniques (distillation, gas or liquid chromatography, mass spectrometry, etc.), which quantify only a limited number of families of molecules however. Reconstruction methods for the petroleum cuts are numerical tools, which allow to evolve towards a molecular detail and which are all based on the following principle: defining simplified but consistent mixtures of chemical compounds from partial analytical data and from expert knowledge of the process under study. Thus, the reconstruction method by entropy maximization, which is proposed in this article, is a recent and powerful technique which allows to determine the molar fractions of a predefined set of chemical compounds by maximizing an entropic criterion and by satisfying the analytical constraints given by the modeler. This approach allows to reduce the number of degrees of freedom from several thousands (corresponding to the molar fractions of the compounds) to several tens (corresponding to the Lagrange parameters associated with the analytical constraints) and to greatly decrease the CPU time required to perform the calculations. This approach has been successfully applied to reconstruct FCC gasolines by precisely predicting the molecular composition of this type of feedstocks from a distillation and an overall PIONA analysis (Paraffins, Isoparaffins, Olefins, Naphthenes and Aromatics). The extension to other naphthas (Straight Run naphthas, Coker naphthas, hydrotreated naphthas, etc.) is straightforward

Statistical Reconstruction of Gas Oil Cuts Reconstruction statistique de coupes gazoles

Gas oil cuts are extremely complex mixtures of several thousands of different chemical species. Consequently, conventional petroleum analyses do not allow to obtain the molecular detail that is required for the development of robust and predictive kinetic models. Recently, two-dimensional Gas Chromatographic techniques (GC2D) have greatly improved the knowledge in the field of characterization of gas oils. However, they remain R&D tools and are hardly utilized in the refining industry. Hence, the goal of the statistical reconstruction of gas oils is to provide a surrogate for this GC2D analysis. To this aim, the gas oil cuts are characterized by means of matrices of molar fractions of pseudo-compounds, which are classified by chemical family and by carbon atom number. The input analyses are the Fitzgerald mass spectrometry, the sulfur speciation (one-dimensional gas chromatography coupled to a specific sulfur chemiluminescence detector) and the total nitrogen and basic nitrogen contents, and allow to quantify the proportions of all the chemical families present in the matrix. The simulated distillation is also used in order to introduce information on the volatility of the gas oil cut. The reconstruction method proposed in this paper is mainly based on a reference statistical distribution of the number of carbon atoms for the side chains connected to the naphtheno-aromatic cores. For each chemical family, the knowledge of the number of potential side chains and the estimation of the maximum length of these alkyl chains allow to determine the carbon number distribution by adjusting of the reference distribution. After reconstruction, the properties of the resulting molar fractions matrix are very close to the analyses used for the reconstruction. Moreover, the method allows to predict, with a high precision, complementary analyses such as the hydrogen content, the aromatic carbon content and the density at 15 ˚C. Finally, the matrix can be efficiently used to develop kinetic models like those employed at IFP to predict the performances of gas oil hydrotreating units. Les coupes gazoles sont des mélanges extrêmement complexes de plusieurs milliers de composés chimiques différents. De ce fait, les analyses pétrolières conventionnelles ne permettent pas d’obtenir un détail moléculaire qui serait pourtant nécessaire aux développements de modèles cinétiques robustes et prédictifs. Récemment, les techniques de chromatographie bidimensionnelle (GC2D) ont entraîné un saut qualitatif important dans le domaine de la caractérisation des gazoles mais celles-ci restent des outils de R&D encore peu généralisés dans l’industrie pétrolière. Par rapport à cette problématique, le but de la reconstruction statistique de gazoles consiste donc à fournir un substitut à l’analyse GC2D en proposant de caractériser les gazoles sous la forme de matrices de fractions molaires de pseudo-composés décrits par famille chimique et nombre d’atomes de carbone. Les analyses utilisées en entrée sont la spectrométrie de masse Fitzgerald, la spéciation soufre (chromatographie monodimensionnelle couplée à un détecteur du soufre par chimiluminescence), les teneurs en azote total et azote basique qui permettent de quantifier les proportions des différentes familles chimiques représentées dans la matrice. La distillation simulée est utilisée quant à elle pour avoir une information sur la volatilité de la coupe gazole. La méthode de reconstruction proposée dans cet article se base principalement sur une distribution statistique de référence du nombre d’atomes de carbone des chaînes alkyles sur les noyaux naphténo-aromatiques. Pour chaque famille chimique, la connaissance du nombre potentiel de chaînes alkyles et l’estimation de la longueur maximale de ces chaînes permettent alors de déterminer la distribution par nombre d’atomes de carbone en dilatant la distribution de référence. Au final, la matrice de fractions molaires obtenue possède des propriétés très proches des analyses utilisées pour la reconstruction. Elle permet aussi de prédire, avec une grande précision, des analyses complémentaires comme la teneur en hydrogène, la teneur en carbone aromatique ou la densité à 15 ˚C. Enfin, elle peut être employée très efficacement dans des modèles cinétiques comme ceux utilisés à l’IFP pour prédire les performances d’un procédé d’hydrotraitement de gazoles

Statistical Reconstruction of Gas Oil Cuts

Gas oil cuts are extremely complex mixtures of several thousands of different chemical species. Consequently, conventional petroleum analyses do not allow to obtain the molecular detail that is required for the development of robust and predictive kinetic models. Recently, two-dimensional Gas Chromatographic techniques (GC2D) have greatly improved the knowledge in the field of characterization of gas oils. However, they remain R&D tools and are hardly utilized in the refining industry. Hence, the goal of the statistical reconstruction of gas oils is to provide a surrogate for this GC2D analysis. To this aim, the gas oil cuts are characterized by means of matrices of molar fractions of pseudo-compounds, which are classified by chemical family and by carbon atom number. The input analyses are the Fitzgerald mass spectrometry, the sulfur speciation (one-dimensional gas chromatography coupled to a specific sulfur chemiluminescence detector) and the total nitrogen and basic nitrogen contents, and allow to quantify the proportions of all the chemical families present in the matrix. The simulated distillation is also used in order to introduce information on the volatility of the gas oil cut. The reconstruction method proposed in this paper is mainly based on a reference statistical distribution of the number of carbon atoms for the side chains connected to the naphtheno-aromatic cores. For each chemical family, the knowledge of the number of potential side chains and the estimation of the maximum length of these alkyl chains allow to determine the carbon number distribution by adjusting of the reference distribution. After reconstruction, the properties of the resulting molar fractions matrix are very close to the analyses used for the reconstruction. Moreover, the method allows to predict, with a high precision, complementary analyses such as the hydrogen content, the aromatic carbon content and the density at 15 ˚C. Finally, the matrix can be efficiently used to develop kinetic models like those employed at IFP to predict the performances of gas oil hydrotreating units

Impact of Oxygenated Compounds from Lignocellulosic Biomass Pyrolysis Oils on Gas Oil Hydrotreatment

Pinheiro, Ana Hudebine, Damien Dupassieux, Nathalie Geantet, ChristopheA potential valorization pathway for pyrolysis oils from lignocellulosic biomass is their co-hydrotreatment with petroleum cuts to produce transportation fuels. The study of simultaneous hydrodeoxygenation (HDO) and hydrodesulfurization (HDS) reactions is therefore essential before considering such a co-treatment. The influence of different oxygenated compounds on the hydrotreatment of a straight-run gas oil was studied on a CoMo/gamma-Al2O3 catalyst and under industrial operating conditions. The selected compounds were 2-propanol, cyclopentanone, anisole, guaiacol, propanoic acid, and ethyldecanoate, which are representative of the oxygenated chemical families present in bio-oils. Reaction schemes of HDO reactions were proposed for each studied oxygenated compound, and their impact on the gas oil HDS, hydrodenitrogenation (HDN), and aromatic ring hydrogenation (HDCA) was determined. Under our operating conditions, 2-propanol, cyclopentanone, anisole, and guaiacol were not found to be inhibitors of catalytic performances. On the contrary, propanoic acid and ethyldecanoate had an inhibiting effect on HDS, HDN, and HDCA reactions. This inhibition is attributed to a competition between the HDS reactions and the methanation of CO and CO2 formed during the decomposition of ethers and acids. The impact on HDS conversion of dibenzothiophenic compounds was also studied, showing no differences of the inhibiting effect between these molecules

Transformation of dibenzothiophenes model molecules over CoMoP/Al2O3 catalyst in the presence of oxygenated compounds

International audienceDecanoic acid is one of the most inhibiting compounds with CO in the transformation of the most refractory sulfur compounds in gas oils. Unlike phenols compounds, decanoic acid and CO its main by-product present a strong inhibiting effect in the conversion of sulfur compounds. The effects are due to phenomena of competitive adsorption between sulfur and oxygen compounds on the catalyst surface. Furthermore, according to oxygenated molecules, the impact on both transformation pathways (HYD and DSD) mainly involved in HDS of gas oils is not the same. Decanoic acid and CO have a greater impact on the DSD way involved in the transformation of DBT than in HYD way involved in the transformation of 46DMDBT. These results confirmed that these two reactions require two different sites located in sulfur and metal edges of the catalys

Membrane Fractionation of Biomass Fast Pyrolysis Oil and Impact of its Presence on a Petroleum Gas Oil Hydrotreatment Fractionnement membranaire d’une huile de pyrolyse flash et impact de sa présence sur l’hydrotraitement d’un gazole atmosphérique

In order to limit the greenhouse effect causing climate change and reduce the needs of the transport sector for petroleum oils, transformation of lignocellulosic biomass is a promising alternative route to produce automotive fuels, chemical intermediates and energy. Gasification and liquefaction of biomass resources are the two main routes that are under investigation to convert biomass into biofuels. In the case of the liquefaction, due to the unstability of the liquefied products, one solution can be to perform a specific hydrotreatment of fast pyrolysis bio-oils with petroleum cuts in existing petroleum refinery system. With this objective, previous studies [Pinheiro et al. (2009) Energy Fuels 23, 1007-1014; Pinheiro et al. (2011) Energy Fuels 25, 804-812] have been carried out to investigate the impact of oxygenated model compounds on a Straight Run Gas Oil (SRGO) hydrotreatment using a CoMo catalyst. The authors have demonstrated that the main inhibiting effects are induced from CO and CO2 produced during hydrodeoxygenation of esters and carboxylic acids. To go further, cotreatment of a fast pyrolysis oil with the same SRGO as used in the previous. studies was investigated in this present work. Firstly the bio-oil was separated into four fractions by membrane fractionation using 400 and 220 Da molecular weight cut-off membranes. The bio-oil and its fractions were analyzed by spectroscopic and chromatographic techniques. Then, one fraction (i.e. fraction enriched in compounds with molecular weight from 220 to 400 Da) was mixed with the SRGO and co-treated. Despite some experimental difficulties mainly due to the emulsion instability, the hydrotreatment was successful. An inhibition has been observed on the hydro treating reactions of the SRGO in presence of the bio-oil fraction. The measurement of the CO/CO2/CH4 molar flowrate at the reactor outlet showed that the inhibition was due to the presence of CO and CO2 coming from HDO rather than to the oxygen compounds themselves. Les ressources limitées en pétrole brut et les limitations en termes de rejet de CO2 suscitent un intérêt fort pour développer de nouvelles bases pour les carburants et la pétrochimie à partir de ressources lignocellulosiques. Deux voies principales sont actuellement étudiées pour transformer cette matière en carburants liquides : la gazéification et la liquéfaction. Dans ce dernier cas, un des traitements possibles serait d’hydrotraiter les huiles de pyrolyse flash en mélange avec des coupes pétrolières conventionnelles telles que les gazoles Straight-Run de manière à utiliser les unités d’hydrotraitement déjà existantes sur les sites de raffinerie. Si des études antérieures mettant en jeu l’hydrotraitement d’un gazole Straight Run (SR), dans des conditions de désulfuration profonde, en présence de molécules oxygénées modèles et d’un catalyseur CoMo/Al2O3 [Pinheiro et al. (2009) Energy Fuels 23, 1007-1014; Pinheiro et al. (2011) Energy Fuels 25, 804-812], ont montré que seul le monoxyde de carbone (CO) ou le dioxyde de carbone (CO2) issus de l’hydrodéoxygénation de certains composés (esters et acides carboxyliques) avaient un fort effet inhibiteur sur les autres réactions d’hydrotraitement et en particulier sur l’hydrodésulfuration des composés soufrés, l’impact du co-traitement du gazole SR et d’une base réelle issue de pyrolyse de lignocellulose n’avait pas encore été quantifié. La présente étude fournit les résultats d’hydrotraitement de ce même gazole co-traité en présence d’une huile de pyrolyse flash ou d’une fraction de cette dernière. Par filtration membranaire, l’huile de pyrolyse a été séparée en quatre fractions en utilisant successivement deux membranes à 400 et 220 Da. La bio-huile ainsi que ses 4 fractions ont ensuite été caractérisées par différentes techniques spectroscopiques et chromatographiques. La fraction enrichie en composés de masse molaire comprise entre 220 et 400 Da a été hydrotraitée avec succès en mélange avec le gazole SR malgré quelques problèmes de stabilité de l’émulsion. L’effet inhibiteur observé sur les réactions d’hydrotraitement est en adéquation avec les quantités de CO/CO2 formées par hydrodéoxygénation des acides carboxyliques quantifiés dans la fraction d’huile de pyrolyse et confirme les mécanismes inhibiteurs démontrés lors du co-traitement sur catalyseur CoMo/Al2O3 d’une charge gazole SR et d’une source oxygénée issue de biomasse

Membrane Fractionation of Biomass Fast Pyrolysis Oil and Impact of its Presence on a Petroleum Gas Oil Hydrotreatment

In order to limit the greenhouse effect causing climate change and reduce the needs of the transport sector for petroleum oils, transformation of lignocellulosic biomass is a promising alternative route to produce automotive fuels, chemical intermediates and energy. Gasification and liquefaction of biomass resources are the two main routes that are under investigation to convert biomass into biofuels. In the case of the liquefaction, due to the unstability of the liquefied products, one solution can be to perform a specific hydrotreatment of fast pyrolysis bio-oils with petroleum cuts in existing petroleum refinery system. With this objective, previous studies [Pinheiro et al. (2009) Energy Fuels 23, 1007-1014; Pinheiro et al. (2011) Energy Fuels 25, 804-812] have been carried out to investigate the impact of oxygenated model compounds on a Straight Run Gas Oil (SRGO) hydrotreatment using a CoMo catalyst. The authors have demonstrated that the main inhibiting effects are induced from CO and CO2 produced during hydrodeoxygenation of esters and carboxylic acids. To go further, cotreatment of a fast pyrolysis oil with the same SRGO as used in the previous. studies was investigated in this present work. Firstly the bio-oil was separated into four fractions by membrane fractionation using 400 and 220 Da molecular weight cut-off membranes. The bio-oil and its fractions were analyzed by spectroscopic and chromatographic techniques. Then, one fraction (i.e. fraction enriched in compounds with molecular weight from 220 to 400 Da) was mixed with the SRGO and co-treated. Despite some experimental difficulties mainly due to the emulsion instability, the hydrotreatment was successful. An inhibition has been observed on the hydro treating reactions of the SRGO in presence of the bio-oil fraction. The measurement of the CO/CO2/CH4 molar flowrate at the reactor outlet showed that the inhibition was due to the presence of CO and CO2 coming from HDO rather than to the oxygen compounds themselves