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Produção, caracterização e determinação de propriedades físico-químicas de catalisadores e suportes utilizados em processos de hidrotratamentoChagas, Luciano Honorato 22 November 2013 (has links)
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Previous issue date: 2013-11-22 / O grande interesse na hidrodessulfurização (HDS) de gasolina é realizar remoção profunda de enxofre e, ao mesmo tempo, reduzir a perda do numero de octanos que ocorre no processo de HDS minimizando a hidrogenação (HID) de olefinas, as quais são benéficas para a octanagem. Além do componente ativo e do promotor, o suporte deve ser considerado uma parte integral do catalisador. Nesse sentido, diversos suportes (incluindo aluminas e óxidos mistos) foram preparados a partir da calcinação de diferentes precursores. Uma amostra de Boehmita comercial foi usada como precursora de polimorfos de alumina. Para comparação, três outros precursores foram sintetizados a partir de diferentes métodos. Particularmente, o uso de excesso de ureia promoveu uma forma muito cristalina de carbonato básico de alumínio. Cada precursor foi calcinado em várias temperaturas gerando polimorfos de alumina, os quais foram analisados estruturalmente por DRX e RMN de 27Al. Devido ao interesse em suportes para catalisador, atenção especial foi dada à fase γ-Al2O3, a qual em adição a investigação estrutural foi submetida à análise textural. Essas quatro amostras de γ-Al2O3 foram utilizadas como suportes para catalisadores do tipo CoMo, que foram testados em reações de HDS de tiofeno e HID de cicloexeno. Os testes catalíticos mostraram que as atividades catalíticas crescem com o aumento do diâmetro médio de poros das fases CoMo/γ-Al2O3, e estão diretamente relacionados à dispersão do molibdênio sobre o suporte. Os resultados mostraram que a partir de diferentes rotas de síntese, e usando uma rota comum de calcinação, podem-se obter materiais com a mesma composição, mas com diferentes propriedades estruturais e texturais. Além disso, catalisadores do tipo CoMo suportados, contendo 20 % de MoO3 e 3 % de CoO, foram preparados por impregnação ao ponto úmido com soluções aquosas de molibdênio e cobalto sobre óxidos mistos obtidos a partir de hidrotalcitas. Os precursores contendo variadas quantidades de Mg, Co e Al ou Ni, Co e Al foram sintetizados pelo método de hidrólise de ureia. A calcinação leva a óxidos mistos cujas características estruturais dependem da composição. A caracterização dos suportes foi feita pelas técnicas de BET, DRX, RMN, IV, UV-vis/DRS e TPR. As amostras sulfetadas foram usadas como catalisadores em reações simultâneas de HDS de tiofeno e HID de cicloexeno. Os resultados foram comparados com catalisadores convencionais CoMo/γ-Al2O3, indicando que as atividades catalíticas dependem dos métodos de preparação dos precursores e suportes. Na série Mg-Co-Al o catalisador com maior quantidade de magnésio mostrou as maiores atividades de HDS e HID, sugerindo que a basicidade está associada com a performance catalítica. Adicionalmente, a amostra sem magnésio e contendo alta quantidade de cobalto exibiu as menores atividades e a maior seletividade (HDS/HID = 3,86). Os resultados indicam que o excesso de cobalto diminui a atividade enquanto a presença de magnésio contribui para aumentá-la. Por outro lado, a série Ni-Co-Al exibiu as menores razões HDS/HID. Nesse caso, as altas atividades para hidrogenação são atribuídas às altas quantidades de níquel. Adicionalmente, uma comparação entre catalisadores contendo 10 % de MoO3 e 3 % de CoO, suportados em óxidos mistos derivados de HDL e um catalisador suportado em alumina, revela que o suporte mais ácido tem maior influência sobre a capacidade de hidrogenação do catalisador. Entretanto, apesar da composição e das características estruturais dos suportes, o método de preparação pode influenciar significativamente no desempenho de um catalisador suportado. / The great interest in hydrodesulfurization (HDS) of gasoline is to perform a deep sulfur removal and, at the same time, to reduce the loss of the octane number occurring in the HDS process, by minimizing the hydrogenation of olefins which are beneficial to this property. Besides the active component and the promoter, the support has to be considered an integral part of the catalyst. In this sense, several supports (enclosing aluminas and mixed oxides) were prepared from calcination of different precursors. A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. Each precursor of alumina was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and 27Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al2O3 phase, which in addition to structural investigation was subjected to textural analysis. These four γ-Al2O3 samples were used as catalyst supports like CoMo, which were tested in reactions of HDS of thiophene and HID of cyclohexene. The catalytic tests show that catalytic activities increase with pore diameters of CoMo/γ-Al2O3 phases and are directly related to dispersion of molybdenum on the support. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties. Furthermore, supported CoMo catalysts containing 20 % of MoO3 and 3 % of CoO were prepared by incipient wetness impregnation of molybdenum and cobalt aqueous solutions over mixed oxides obtained from hydrotalcite precursors. The precursors, containing varying amounts of Mg, Co and Al or Ni, Co and Al cátions, were synthesized by urea hydrolysis method. The calcination led to mixed oxides whose structural characteristics depend on the composition. Characterization of the supports by BET, XRD, NMR, FTIR, UV-vis/DRS and TPR techniques was carried out. The sulfided samples were used as catalysts in simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene. The results were compared with conventional CoMo/γ-Al2O3 catalysts, which indicate that the catalytic activities depend on the preparation method of the precursors and supports. In the Mg-Co-Al series, the high magnesium content catalyst show higher HDS and HYD activities, suggesting that the support basicity is associated with catalytic performance. Furthermore, the free magnesium and high cobalt content catalyst show lower activities and higher selectivity (HDS/HYD = 3.86). The results indicate that the excess of cobalt decreases the activities while the presence of magnesium contributes to improve them. Otherwise, the Ni-Co-Al series show the smaller HDS/HYD ratios. In this case, the higher hydrogenation activities are assigned to high nickel content. Additionally, a comparison between catalysts containing 10 % of MoO3 and 3 % of CoO, supported on mixed oxides derived of LDH and a catalyst supported on alumina reveals that the most acidic support (alumina) has great influence over hydrogenation capacity of the catalyst. However, besides the composition and structural characteristics of the supports, the preparation method can to influence significantly the performance of a supported catalyst.
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Εffect οf the suppοrt οn the activity and mοrphοlοgy οf hydrοdesulfurizatiοn catalysts / Effet du support sur la morphologie et l'activité des catalyseurs d'hydrodésulfurationDominguez Garcia, Elizabeth 19 December 2017 (has links)
L'influence de l'effet de support sur la formation des phases de sulfure, c'est-à-dire la morphologie, la dispersion des sites, la structure et l'activité catalytique pour les catalyseurs d'hydrotraitement a été étudiée. L'étude a débuté par des catalyseurs au Mo et a été suivie par des catalyseurs CoMo supportés sur de la silice d'alumine et de l'oxyde de titane. L'effet de support semble être le facteur clé pour contrôler la morphologie des feuilles de MoS2. La morphologie a été étudiée en utilisant une technique puissante appelée IR / CO, c'est-à-dire une adsorption de CO suivie par une spectroscopie FTIR. Cette méthode permet de distinguer deux types de bord exposés sur les feuilles MoS2 dites M- et S-edge et permet ensuite l'étude de la morphologie par le rapport S / M-edge. Ainsi, pour une interaction faible, la morphologie hexagonale déformée du support MoS2 a été montrée alors que pour une interaction forte, la morphologie du triangle a été observée. Ces différentes morphologies ont été utilisées pour étudier la localisation du Co par la même méthode, IR / CO. Cette méthode permet également la distinction entre les sites non promus et promus ainsi que Co situé sur les bords M- et S-edge. Par conséquent, la comparaison entre le rapport S / M-edge et le degré de promotion (rapport des sites promus / non promus) a montré que Co est présent sur les deux bords M- et S-edge pour les trois catalyseurs supportés par CoMo. De plus, une étude détaillée a montré que Co décore préférentiellement les sites de type S-edge. Par conséquent, les structures du site CoMoS pour chaque catalyseur ont été étudiées par la méthode IRIS 2D. Cette nouvelle méthode développée au LCS permet la déconvolution de bandes IR / CO qui étaient auparavant une limitation pour la caractérisation des sites CoMoS. Cette avancée dans la caractérisation CoMo a conduit à l'étude détaillée de la structure CoMoS. Après l'attribution des trois bandes qui sont observées dans la gamme de spectres IR / CO promue, il est apparu que les sites S-edge étaient partiellement promus par Co, tandis que les sites M-edge étaient partiellement et totalement promus par Co. Ces sites ont un effet sur la réactivité HDS (hydrodésulfuration). De plus, une activité intrinsèque plus élevée a été trouvée pour le bord M-edge partiellement promus par Co, suivi par les sites totalement promus et finalement promus partiellement par le bord S-edge. / The influence of the support effect on the sulfide phases formation, i.e. morphology, sites dispersión, structure and catalytic activity for hydrotreating catalysts was studied. The study started by Mo catalysts and followed by CoMo catalysts supported on alumina silica and titania. The support effect appeared to be the key factor to control the morphology of MoS2 slabs. The morphology was studied using a powerful technique so-called IR/CO, i.e. CO adsorption followed by FTIR spectroscopy. This method allows the distinction of two types of edge exposed on the MoS2 slabs so-called M- and S-edge and then permits the study of the morphology by the S-/M-edge ratio. Thus, for a weak interaction MoS2-support deformed hexagon morphology was detected whereas for a strong interaction triangle morphology was observed. These different morphologies were used to study the Co localization by the same method, IR/CO. This method also allows the distinction between non- and promoted sites as well as Co located on M- and S-edges. Hence, the comparison between S-/M-edge ratio and promotion degree (promoted/non-promoted sites ratio) showed that Co is present on both M- and S-edges for the three CoMo supported catalysts. Additionally, a detailed study showed that Co preferentially decorates S-edge sites. Consequently, the CoMoS site structures for each catalyst has been studied by 2D IRIS method. This novel method developped in LCS allows the resolution of overlapping IR/CO bands which were previously a limitation for CoMoS sites characterization. This advance in the CoMo characterization lead to the study of detailed CoMoS structure. After the assignment of three bands which are observed in the promoted range of IR/CO spectra, it appeared that S-edge sites were partially promoted by Co, whereas M-edge sites could be partially and totally promoted by Co. The different proportion of those sites have an effect on HDS (hydrodesulfuration) reactivity. Thus, higher intrinsic activity was found for M-edge partially promoted by Co followed by totally promoted and finally the S-edge partially promoted sites.
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Kinetic Modelling Simulation and Optimal Operation of Trickle Bed Reactor for Hydrotreating of Crude Oil. Kinetic Parameters Estimation of Hydrotreating Reactions in Trickle Bed Reactor (TBR) via Pilot Plant Experiments; Optimal Design and Operation of an Industrial TBR with Heat Integration and Economic Evaluation.Jarullah, Aysar Talib January 2011 (has links)
Catalytic hydrotreating (HDT) is a mature process technology practiced in the
petroleum refining industries to treat oil fractions for the removal of impurities (such as
sulfur, nitrogen, metals, asphaltene). Hydrotreating of whole crude oil is a new
technology and is regarded as one of the more difficult tasks that have not been reported
widely in the literature. In order to obtain useful models for the HDT process that can
be confidently applied to reactor design, operation and control, the accurate estimation
of kinetic parameters of the relevant reaction scheme are required. This thesis aims to
develop a crude oil hydrotreating process (based on hydrotreating of whole crude oil
followed by distillation) with high efficiency, selectivity and minimum energy
consumption via pilot plant experiments, mathematical modelling and optimization.
To estimate the kinetic parameters and to validate the kinetic models under different
operating conditions, a set of experiments were carried out in a continuous flow
isothermal trickle bed reactor using crude oil as a feedstock and commercial cobaltmolybdenum
on alumina (Co-Mo/¿-Al2O3) as a catalyst. The reactor temperature was
varied from 335°C to 400°C, the hydrogen pressure from 4 to10 MPa and the liquid
hourly space velocity (LHSV) from 0.5 to 1.5 hr-1, keeping constant hydrogen to oil
ratio (H2/Oil) at 250 L/L. The main hydrotreating reactions were hydrodesulfurization
(HDS), hydrodenitrogenation (HDN), hydrodeasphaltenization (HDAs) and
hydrodemetallization (HDM) that includes hydrodevanadization (HDV) and
hydrodenickelation (HDNi).
An optimization technique is used to evaluate the best kinetic models of a trickle-bed
reactor (TBR) process utilized for HDS, HDAs, HDN, HDV and HDNi of crude oil
based on pilot plant experiments. The minimization of the sum of the squared errors
(SSE) between the experimental and estimated concentrations of sulfur (S), nitrogen
(N), asphaltene (Asph), vanadium (V) and nickel (Ni) compounds in the products, is
used as an objective function in the optimization problem using two approaches (linear
(LN) and non-linear (NLN) regression).
The growing demand for high-quality middle distillates is increasing worldwide
whereas the demand for low-value oil products, such as heavy oils and residues, is
decreasing. Thus, maximizing the production of more liquid distillates of very high
quality is of immediate interest to refiners. At the same time, environmental legislation
has led to more strict specifications of petroleum derivatives. Crude oil hydrotreatment
enhances the productivity of distillate fractions due to chemical reactions. The
hydrotreated crude oil was distilled into the following fractions (using distillation pilot
plant unit): light naphtha (L.N), heavy naphtha (H.N), heavy kerosene (H.K), light gas
oil (L.G.O) and reduced crude residue (R.C.R) in order to compare the yield of these
fractions produced by distillation after the HDT process with those produced by
conventional methods (i.e. HDT of each fraction separately after the distillation). The
yield of middle distillate showed greater yield compared to the middle distillate
produced by conventional methods in addition to improve the properties of R.C.R.
Kinetic models that enhance oil distillates productivity are also proposed based on the
experimental data obtained in a pilot plant at different operation conditions using the
discrete kinetic lumping approach. The kinetic models of crude oil hydrotreating are
assumed to include five lumps: gases (G), naphtha (N), heavy kerosene (H.K), light gas
oil (L.G.O) and reduced crude residue (R.C.R). For all experiments, the sum of the
squared errors (SSE) between the experimental product compositions and predicted
values of compositions is minimized using optimization technique.
The kinetic models developed are then used to describe and analyse the behaviour of an
industrial trickle bed reactor (TBR) used for crude oil hydrotreating with the optimal
quench system based on experiments in order to evaluate the viability of large-scale
processing of crude oil hydrotreating. The optimal distribution of the catalyst bed (in
terms of optimal reactor length to diameter) with the best quench position and quench
rate are investigated, based upon the total annual cost.
The energy consumption is very important for reducing environmental impact and
maximizing the profitability of operation. Since high temperatures are employed in
hydrotreating (HDT) processes, hot effluents can be used to heat other cold process
streams. It is noticed that the energy consumption and recovery issues may be ignored
for pilot plant experiments while these energies could not be ignored for large scale
operations. Here, the heat integration of the HDT process during hydrotreating of crude
oil in trickle bed reactor is addressed in order to recover most of the external energy.
Experimental information obtained from a pilot scale, kinetics and reactor modelling
tools, and commercial process data, are employed for the heat integration process
model. The optimization problem is formulated to optimize some of the design and
operating parameters of integrated process, and minimizing the overall annual cost is
used as an objective function.
The economic analysis of the continuous whole industrial refining process that involves
the developed hydrotreating (integrated hydrotreating process) unit with the other
complementary units (until the units that used to produce middle distillate fractions) is
also presented.
In all cases considered in this study, the gPROMS (general PROcess Modelling
System) package has been used for modelling, simulation and parameter estimation via
optimization process. / Tikrit University, Iraq
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Une nouvelle approche dans l’évaluation de l’effet de support des catalyseurs d’hydrodésulfuration / A new approach in the evaluation of support effect with hydrodesulfurization catalystsNinh, Thi Kim Thoa 02 February 2011 (has links)
L’objectif de ce travail est d’évaluer l’effet de la nature du support et l’effet de promotion sur les propriétés catalytiques des catalyseurs d’HDS à base de Mo. Pour obtenir les systèmes catalytiques adéquats, nous avons appliqué la préparation par « voie acac », qui consiste à faire réagir le promoteur sous forme de complexe acétylacétonate (de Co, Ni ou Fe) sur le sulfure de molybdène supporté (sur γ-Al2O3, SiO2, TiO2 ou ZrO2). Les différents solides obtenus ont été caractérisés par MET, IR(CO) et SPX notamment pour tenter de quantifier les phases actives, puis ils ont été testés dans les réactions d’HDS du thiophène et du 4,6-DMDBT. L’activité catalytique a pu être corrélée aux résultats de caractérisation par une nouvelle approche qui consiste à calculer l’activité apparente par site NiMoS ou CoMoS. Cette approche montre que la qualité des sites actifs CoMoS et NiMoS est la meilleure sur SiO2 et comparable sur les supports γ-Al2O3, TiO2 et ZrO2. Par la même méthode nous avons préparé de nouveaux catalyseurs de type CoNiMoS supportés, en ajoutant les promoteurs Co et Ni soit simultanément soit successivement au MoS2. Cette étude permet un fort apport expérimental aux études théoriques qui avancent l’hypothèse de différentes affinités du Co et du Ni pour les deux type de bords S-edge et Mo-edge sur γ-Al2O3 et TiO2. / The main objective of this work was to evaluate the support and the promoting effect on the catalytic properties of HDS catalysts. In order to obtain appropriate catalytic systems, we applied the “acac method” which consists to add the promoter as an acetylacetonate complex (of Co, Ni or Fe) onto the supported molybdenum sulfide (on γ-Al2O3, SiO2, TiO2 and ZrO2). The various solids obtained were characterized by TEM, IR(CO) and XPS in particular to quantify the active phases, and then they have been tested in the HDS reactions of thiophene and 4,6-DMDBT. The catalytic activity has been correlated to the characterization datas by a new approach which consists in calculating the apparent catalytic activity by NiMoS or CoMoS site. This approach showed that the quality of the active sites is the best on SiO2 and comparable on γ-Al2O3, TiO2 and ZrO2. Moreover, this “acac method” allowed us to study supported CoNiMoS catalysts synthesized by adding Co and Ni either simultaneously or successively to MoS2. This study represents an important experimental contribution which allow to discuss the hypothesis developped in theoretical studies about the different affinities of Co and Ni for the S-edge and Mo-edge on γ-Al2O3 and TiO2.
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