Spéciation du Silicium dans les charges d'hydrotraitement

Le silicium est connu pour être un poison sévère des catalyseurs d'hydrotraitement (HDT). L objectif de la thèse a donc été de mettre en place des outils analytiques pour la spéciation du silicium afin d'identifier toutes les molécules silicées réellement formées dans les charges d'HDT. Différents outils analytiques de pointe basés sur des couplages entre la chromatographie en phase gazeuse et la spectrométrie de masse (MS et ICP/MS) ont été développés. Étant donnée la réactivité de certaines espèces silicées, des échantillons représentatifs de la dégradation du PDMS ont été produits dans des conditions de craquage thermique d'un mélange heptane/xylène. L'application à ces échantillons de la stratégie analytique, développée initialement, a démontré la présence du silicium sous différentes formes chimiques. Plus d une centaine de molécules réparties en 10 familles comprenant un nombre d atomes de silicium entre 1 et 1500 a été caractérisée. Ces composés silicés vont donc pouvoir être présents dans toutes les coupes pétrolières, des fractions gaz aux fractions les plus lourdes, couvrant ainsi un domaine de coupes pétrolières beaucoup plus vaste que celui des essences. Les siloxanes cycliques (Dn) ont été confirmés comme produits majoritaires de dégradation du PDMS. Les autres composés silicés, jamais caractérisés pour la plupart, sont présents à l état de traces mais possèdent des groupements réactifs de type hydroxy, métoxy, hydropéroxy susceptibles d interagir fortement avec le support du catalyseur (Al2O3) et donc de conduire à sa désactivation.Silicon is known to be a severe poison for hydrotreatment (HDT) catalysts especially in naphtha and gasoline samples. The objective of the PhD was to develop analytical methods for silicon speciation in order to characterize silicon molecules formed during refining steps which potentially affects HDT catalysts. For the analytical strategy, different high-technology analytical tools based on gas chromatography coupled to mass spectrometry (MS and ICP/MS) were developed. Due to the high reactivities of several silicon species, representative samples of PDMS degradation were produced under thermal cracking of a mixture of heptane/xylene (500C) using a pilot plant. The previously developed analytical strategy was applied to these samples and demonstrated the occurrence of silicon under a wide array of chemical forms. More than a hundred of silicon species belonging to 10 chemical families with a number of silicon atoms ranging from 1 to 1,500 were characterized. These silicon compounds could be present in all petroleum cuts, from the gas fractions to the heavier fractions. Therefore, the investigated range of boiling points was inevitably more important than for naptha and gasoline cuts. Cyclic siloxanes (Dn) were confirmed as the major PDMS degradation products. The other silicon compounds, almost never characterized before, were recovered at trace levels but consisted of reactive groups such as hydroxy, methoxy and hydroperoxy. These silicon species were able to strongly react with the catalytic support (Al2O3) and led to its deactivationPAU-BU Sciences (644452103) / SudocSudocFranceF

Silicon speciation in light petroleum products using gas chromatography coupled to ICP-MS/MS

Silicon speciation in light petroleum products through the hyphenation of gas chromatography with ICP-tandem mass spectrometry (GC-ICP-MS/MS) is described in the present work. Eleven silicon compounds (nine siloxanes, trimethylsilanol and triethylsilane) have been taken as model molecules. The carrier and optional gas flow rates as well as the hydrogen gas flow rate in the octopole reaction cell (ORC) were critical variables. They precluded both the sensitivity and the extent of the effects caused by the sample matrix and silicon nature. The optimization of the latter variable mitigated the m/z 28 interference (14N14N+ and 12C16O+). Moreover, under the optimized conditions, a universal response was found irrespective of the silicon chemical form and sample matrix. The analytical performances of the method have been evaluated. Thus, the ICP-MS/MS response was linear between 0 and 500 μg kg−1 with correlation coefficients up to 0.999, whereas the limit of quantification (LOQ) ranged from 8 to 60 μg kg−1. Moreover, no drift was found for quality control samples analysed along a given analytical run. Only, the most volatile compound, i.e., trimethylsilanol (TMSOH), induced a drop in sensitivity caused by its partial evaporation from the GC vial. The method was validated by the analysis of real samples and the results were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray fluorescence. No significant differences in Si total content provided by the three methods were found. These results demonstrated that all silicon species were taken into account using GC-ICP-MS/MS as the speciation method. Real light petroleum products, especially coker naphtha samples, were analyzed and it was verified that they only contained cyclic siloxanes (D3–D6), mainly hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasiloxane (D4).The authors wish to thank the Spanish Ministry of Science, Innovation and Universities for the financial support (Project Ref. PGC2018-100711-B-I00)

Silicon Speciation in Hydrotreatment Feeds

Le silicium est connu pour être un poison sévère des catalyseurs d'hydrotraitement (HDT). L’objectif de la thèse a donc été de mettre en place des outils analytiques pour la spéciation du silicium afin d'identifier toutes les molécules silicées réellement formées dans les charges d'HDT. Différents outils analytiques de pointe basés sur des couplages entre la chromatographie en phase gazeuse et la spectrométrie de masse (MS et ICP/MS) ont été développés. Étant donnée la réactivité de certaines espèces silicées, des échantillons représentatifs de la dégradation du PDMS ont été produits dans des conditions de craquage thermique d'un mélange heptane/xylène. L'application à ces échantillons de la stratégie analytique, développée initialement, a démontré la présence du silicium sous différentes formes chimiques. Plus d’une centaine de molécules réparties en 10 familles comprenant un nombre d’atomes de silicium entre 1 et 1500 a été caractérisée. Ces composés silicés vont donc pouvoir être présents dans toutes les coupes pétrolières, des fractions gaz aux fractions les plus lourdes, couvrant ainsi un domaine de coupes pétrolières beaucoup plus vaste que celui des essences. Les siloxanes cycliques (Dn) ont été confirmés comme produits majoritaires de dégradation du PDMS. Les autres composés silicés, jamais caractérisés pour la plupart, sont présents à l’état de traces mais possèdent des groupements réactifs de type hydroxy, métoxy, hydropéroxy susceptibles d’interagir fortement avec le support du catalyseur (Al2O3) et donc de conduire à sa désactivation.Silicon is known to be a severe poison for hydrotreatment (HDT) catalysts especially in naphtha and gasoline samples. The objective of the PhD was to develop analytical methods for silicon speciation in order to characterize silicon molecules formed during refining steps which potentially affects HDT catalysts. For the analytical strategy, different high-technology analytical tools based on gas chromatography coupled to mass spectrometry (MS and ICP/MS) were developed. Due to the high reactivities of several silicon species, representative samples of PDMS degradation were produced under thermal cracking of a mixture of heptane/xylene (500°C) using a pilot plant. The previously developed analytical strategy was applied to these samples and demonstrated the occurrence of silicon under a wide array of chemical forms. More than a hundred of silicon species belonging to 10 chemical families with a number of silicon atoms ranging from 1 to 1,500 were characterized. These silicon compounds could be present in all petroleum cuts, from the gas fractions to the heavier fractions. Therefore, the investigated range of boiling points was inevitably more important than for naptha and gasoline cuts. Cyclic siloxanes (Dn) were confirmed as the major PDMS degradation products. The other silicon compounds, almost never characterized before, were recovered at trace levels but consisted of reactive groups such as hydroxy, methoxy and hydroperoxy. These silicon species were able to strongly react with the catalytic support (Al2O3) and led to its deactivatio

Understanding the impact of silicon compounds on metallic catalysts through experiments and multi-technical analysis

AbstractThe presence of silicon in petroleum products is a major issue due to its poisoning effect on catalysts. The aim of this work is to combine silicon speciation and poisoning tests. Cyclic siloxanes were the main silicon species found in petroleum products. Other silicon compounds, comprising reactive groups (hydroxy, methoxy and hydroperoxy), were also recovered but at trace levels using GC-ICP/MS. Five well-chosen silicon compounds were used to poison Pd/alumina catalysts. Only dimethoxydimethylsilane poisons Pd-catalysts while polydimethylsiloxane (PDMS) has no effect on their activities in buta-1,3-diene hydrogenation. Unexpectedly, triethylsilane, triethylsilanol and even octamethylcyclotetrasiloxane (D4) exhibit a promoting effect. An interpretation of the phenomena based on various characterizations is proposed

Approche cinétique du rôle de l’acidité des catalyseurs NiMo sulfures supportés lors de la réaction d’hydrodésazotation de la quinoléine

National @ ECI2D+MNG:CGE:MTFInternational audienceL’hydrodésazotation (HDN) est un procédé de plus en plus important dans le raffinagepétrolier qui traite des charges de plus en plus lourdes car il évite l’empoisonnement ultérieur des catalyseurs d’hydrocraquage ou de craquage catalytique. En raison de la complexité des produits pétroliers, l’approche cinétique de la réaction d’HDN à l’aide de molécules modèles est un outil indispensable à la compréhension des effets des supports ou de dopants pour le développement de systèmes catalytiques plus performants. Ainsi, cette étude porte sur l’HDN de la quinoléine, diluée dans un mélange (squalane/xylène), dans un réacteur fermé, avec 2 catalyseurs sulfures NiMo supportés sur γ-Al2O3 et SiO2-Al2O3. L’approche cinétique élaborée à partir d’un modèle de type Langmuir-Hinshelwood suppose l’adsorption compétitive de la quinoléine, des intermédiaires et de l’ammoniaque sur le même site actif et prends en compte le transfert gaz liquide. Le modèle couplé aux résultats expérimentaux permet l’estimation des constantes cinétiques de chaqueétape de la réaction, les constantes d’adsorption et les chaleurs d’adsorption. Les 2 catalyseurs présentent la même activité volumique en hydrogénation du toluène,mais le NiMo/SiO2-Al2O3 est beaucoup plus acide que le NiMo/γ-Al2O3. Cette différence d’acidité a été mise en évidence par la conversion isomérisante du cyclohexane. Un ensemble de caractérisations (IR CO, XPS) permet de déterminer la teneur en phase promue et d’évaluer les activités intrinsèques de chaque catalyseur.Les résultats de l’estimation montrent que l’hydrogénation de la 1,4THQ en DHQ est l’étapelimitante de la voie réactionnelle principale (1,4THQ→DHQ→PCHA→ PCHE+PCH), pour les 2 catalyseurs (Figure 1). Les valeurs des constantes cinétiques intrinsèques du NiMo/SiO2-Al2O3 sont plus élevées, surtout dans le cas de l’hydrogénation de la 1,4THQ, ce qui peut être lié à la modification électronique de la phase promue. D’autre part, le NiMo/SiO2-Al2O3 favorise fortement la rupture de la liaison Csp2-N dans l’OPA pour former le PB. Les enthalpies d’adsorption des composés azotés varient entre 40 et 50 kJ/mol et diminuent dans cet ordre : DHQ+PCHA > Q+5,8THQ > NH3 > 1,4THQ+OPA. Les azotés sont plus fortement adsorbés sur NiMo/SiO2-Al2O3

Kinetic Modeling of Quinoline Hydrodenitrogenation over a NiMo(P)/Al2O3 Catalyst in a Batch Reactor

SSCI-VIDE+ECI2D+MTF:CGEInternational audienc

Indole Hydrodenitrogenation over Alumina and Silica Alumina-Supported Sulfide Catalysts Comparison with Quinoline

SSCI-VIDE+ECI2D+CGEInternational audienc

Molecular-Level Insights into Coker/Straight-Run Gas Oil Hydrodenitrogenation by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

International audienceThis paper aims to understand the reactivity of different nitrogen species during the catalytic hydro-denitrogenation (HDN) of a mixture of straight-run gas oil and coker gas oil. Effluents at different HDN conversions wereanalyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS), with electrospray ionization (ESI).Positive ESI (ESI(+)) allows a selective ionization of basic nitrogen compounds, whereas negative ESI (ESI(−)) leads toselective ionization of neutral nitrogen compounds. FT-ICR/MS in ESI(+) or (−) mode generates distributions of the nitrogencompounds in the basic and neutral class, respectively, according to their carbon number and double bond equivalent (DBE),which is related to the degree of aromaticity and the number of rings. The evolution of the DBE distribution and the carbonnumber distribution as a function of HDN conversion gives rich information concerning the main reaction pathways and thereactivity of different nitrogen species. For the basic compounds, a shift to a lower DBE was observed, which was interpretedasthe formation of partially hydrogenated or ring-opened intermediates. These intermediates were then slowly converted to the final HDN products. At intermediate conversion levels, especially light compounds were accumulated as intermediates whereas the heavy compounds were directly converted to HDN products, probably due to preferential adsorption. The neutralcompounds showed a very different behavior. At the early reaction stages, they were quickly converted to HDN products, but at high conversion, the conversion of residual carbazole and tetrahydrobenzocarbazole compounds was completely inhibited. The inhibition was probably provoked by the formation of partially hydrogenated basic intermediates, which were stronger inhibitors than the aromatic pyridine rings in the feed. The contribution of cracking reactions was weak, since the overall carbon number distribution of the nitrogen compounds did not change much during hydrotreatmen