Vacuum Gas Oil Hydrotreatment Research Articles

Nitrogen-containing compounds of Kazakhstan petroleum vacuum gas oil

Relevance. The need to accumulate data on nitrogen-containing compounds of heavy fractions, the share of which in secondary oil refining is steadily increasing every year. With the weight of raw materials the amount of sulfur-, nitrogen- and oxygen-containing components in it increases. The high content of heteroatomic compounds has a negative impact on catalytic processing, the quality and performance characteristics of the products obtained, and the environment. One of the widespread processes for upgrading crude oil, in particular, vacuum gas oil, is hydrotreating. However, during the catalytic hydrodesulfurization of heavy distillates the reactions of hydrogenolysis of organic sulfur compounds are inhibited in the presence of nitrogen-containing compounds. At the same time, the degree of hydrodenitrogenation of heavy oil fractions is relatively low. It is known that petroleum nitrogen-containing compounds are divided into nitrogenous bases titrated with acid solutions and nonbasic nitrogen compounds. Nitrogenous bases are represented mainly by alkylbenzo- and alkylnaphthenobenzo derivatives of pyridine. Nonbasic compounds may include benzologs of pyrrole and amides. Determining the composition of nitrogen-containing compounds in vacuum gas oil and studying their transformations during hydrotreatment is an important and actual problem. Aim. Comparative study of high- and low-molecular nitrogenous bases and nonbasic nitrogen-containing compounds of vacuum gas oil of Kazakhstan oil before and after hydrotreating. Objects. Samples taken before and after the catalytic hydrotreatment of vacuum gas oil from Kazakhstan oil. Methods. Hydrotreatment, elemental analysis, potentiometric titration, benzene cryoscopy, IR and 1H NMR spectroscopy, structural group analysis. Results. The paper introduces a comparative characteristic of the composition and structure of high and low molecular weight nitrogenous bases from the original and hydrotreated vacuum gas oil. Under the conditions of hydrotreatment, the total removal of nitrogen was 6.56 wt %, and the content of Nbas. decreased by 36%. At the same time, nitrogenous bases in the hydrotreated product are characterized by low molecular weights. Using IR spectroscopy, similar structural fragments were identified in the nitrogen compounds of the original and hydrotreated vacuum gas oil: pyridine rings (1573–1574 cm–1), carboxylic (3209–3225 and 1701–1709 cm–1) and sulfoxide (1032–1033 cm–1) groups. Among the nitrogen-containing compounds of the original vacuum gas oil, amides (1647–1648 cm–1) were identified, which are absent in the composition of nitrogen-containing compounds of the hydrotreated vacuum gas oil. Hydrocarbon skeletons of molecules include aromatic (1599–1602 cm–1) and aliphatic fragments (2860–2960 and 1454–1460, 1377, 723–727 cm–1). In accordance with the results of the structural group analysis, the averaged molecules of high and low molecular weight nitrogenous bases of the original and hydrotreated vacuum gas oil are represented by naphthenoaromatic structures with different alkyl framing. The differences observed between the values of individual structural parameters of the nitrogenous bases average molecules of the original and hydrotreated vacuum gas oil may indicate the compounds transformations under study during hydrotreatment.

Mathematical Modeling of Vacuum Gasoil Hydrotreatment

Mathematical Modeling of Vacuum Gasoil Hydrotreatment

Mathematical Modeling of the Vacuum Gas Oil Hydrotreatment

Thermochemical properties of molecules and thermodynamic characteristics of vacuum distillate hydrotreatment were calculated by quantumchemical methods. A kinetic model of the hydrotreatment process was developed using a formalized transformation scheme of hydrocarbons. The developed kinetic model was employed in numerical studies aimed to estimate the effect of the feedstock composition on the residual content of heteroatomic components in the product of vacuum gas oil hydrotreatment, the effect of temperature on the content of aromatic hydrocarbons, nitrogen and sulfur in the hydrotreatment product, and the effect of the hydrogen-containing gas consumption on the content of sulfur and hydrogen sulfide in the hydrotreated vacuum gas oil.

Molecular analysis of nitrogen-containing compounds in vacuum gas oils hydrodenitrogenation by (ESI+/-)-FTICR-MS

This paper is a part of a study on reactivity descriptors in vacuum gas oil hydrotreatment (VGO HDT). It aims to understand the differences in feeds of various process origins and the corresponding hydrotreated effluents on a molecular level. Four different vacuum gas oils were hydrotreated over a sulfided NiMo/Al2O3 catalyst at a wide range of temperatures and residence times in order to collect HDT effluents at a broad range of hydrodenitrogenation (HDN) conversions. Vacuum gas oils and HDT effluents have been analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) in positive ESI(+) and negative ESI(-) electrospray ionization modes to characterize the basic and neutral nitrogen-containing species and the subtleties of HDT transformations depending on the feedstock type.

Influence of CeO2 loading on the catalytic performance of CoNiMoS/CeO2–Al2O3 toward vacuum gas oil hydrotreatment

This work investigates the effect of CeO2 doping into the CoNiMoS/Al2O3 catalyst on the efficiency of heavy vacuum gas oil (HVGO) hydrotreatment. Particularly, two supports contain 10% and 25% CeO2 to Al2O3 were prepared by co-precipitation method. Metals were subsequently loaded onto these supports via impregnation technique. The produced catalysts had been then sulfided before introduction to the hydrotretment process. Structural characteristics of supports and catalysts were verified by X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), Transmission electron microscope (TEM) and N2-physiosorption technique. Obvious variations in both morphology and values of surface features could be detected via incorporation of ceria with alumina. The10%CeO2 doped catalyst could successfully attain high percentages of simultaneous hydrodesulfurization and hydrodenitrogenation affinity: 94.8% and 95.45% respectively. This increased the catalytic activity, which had been 30% higher than of using alumina individually, could be attributed to the presence of ceria within the composition of support.

Optimization of Properties of the Alumina Support of Hydrotreatment Catalysts by Introducing Boron and Sulfur at the Stage of Pseudoboehmite Synthesis via Hydrothermal Treatment of the Product of Flash Thermal Treatment

Under discussion is optimization of texture and chemical composition of alumina as the support for the catalyst for hydrotreatment of vacuum gasoil synthesized using the environmentally friendly modern technology of flash thermal treatment of gibbsite. Approaches to increasing the specific surface area by introducing inorganic admixtures (including boron or sulfur) at the stage of synthesis of pseudoboehmite were developed. The introduction of these modifiers was established to increase SBET by 50–100 m2/g comparing to the maximal areas attaineddue to variation in the standard process parameters of the hydrothermal treatment. It was shown that the introduction of boron at the stage of pseudoboehmite synthesis resulted in no less than two times increase in the catalytic activity of CoNiMoP to hydrodesulfurization and hydrodenitrogenation against the activity of a similar catalyst with boron introduced with the impregnating solution.

Inhibiting HDS and HYD reactions with quinoline on Co(Ni)–PMo(W)/Al2O3 catalysts: Effect of active phase composition on stability in the hydrotreatment of a model petroleum raw material

Со(Ni)–PMo(W)/Al2O3 catalysts are prepared using Keggin heteropoly acids H3PMo(W)12O40 and cobalt (nickel) citrate. The physicochemical properties of the catalysts are studied via low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Their catalytic properties are determined in the hydrotreatment of a model raw material containing dibenzothiophene, naphthalene, and different amounts of quinoline (up to 1000 ppm of nitrogen), and in the hydrotreatment of a straight-run diesel fraction and vacuum gas oil. The composition of Со(Ni)–PMo(W)/Al2O3 catalysts plays an important role in the hydrotreatment of a complex hydrocarbon raw material. Ni–PW/Al2O3 catalyst is more resistant to organonitrogen inhibitors than Ni(Co)–PMo/Al2O3 samples with more reactive active sites. Ni–PW/Al2O3 catalyst provides the greatest depth of conversion for sulfur- and nitrogen-containing compounds and polycyclic aromatic hydrocarbons in the hydrotreatment of vacuum gas oil.

Quinoline Inhibiting of Hydrodesulfurization and Hydrogenation Reactions over Co(Ni)PMo(W)/Al2O3 Catalysts: Influence of the Active Phase Composition on the Stability during Hydrotreatment of Model and Oil Feedstock

Co(Ni)-PMo(W)/Al 2 O 3 catalysts were prepared using Keggin heteropoly acids H 3 PMo(W) 12 O 40 and cobalt (nickel) citrate. Physicochemicalproperties of the catalysts were characterized using low-temperature nitrogen adsorption, XPS and HRTEM techniques. Catalytic properties were studied during hydrotreatment of a model feedstock containing dibenzothiophene, naphthalene and quinoline in different proportions (up to 1000 ppm of nitrogen), as well as during hydrotreatment of straight-run diesel fraction and vacuum gasoil. The composition of Со(Ni)-PMo(W)/Al 2 O 3 catalysts was shown to play a crucial role in the hydrotreatment of complex hydrocarbon feedstock. The Ni-PW/Al 2 O 3 catalyst was more stable to organonitrogen inhibitors than Ni(Co)-PMo/Al 2 O 3 bearing more reactive active centers. The highest conversions of sulfur- and nitrogen-containing compounds and polycyclic aromatic hydrocarbons during hydrotreatment of vacuum gasoil were observed with the Ni-PW/Al 2 O 3 catalyst.

Development of New Russian Catalysts for Deep Hydroconversion of Vacuum Gasoil

New Russian catalysts for deep hydrotreatment and hydrocracking of vacuum gasoil (VGO) were developed at the Boreskov Institute of catalysis in cooperation with the Institute for Hydrocarbon Processing and Topchiev Institute of Petrochemical Synthesis. The work was supported by the JSC Gazpromneft-Omsk Refinery under the Complex Project «Creation of the technology for the production of import-substituting catalysts for deep hydroconversion of vacuum gasoil» in the framework of the Federal Targeted Program “Research and Development in Priority Areas of the Scientific and Technological Complex of Russia for 2014–2020”. The high efficiency of the catalysts was experimentally proved. Preliminary works on implementation of the developed technologies for the production of the VGO hydrotreatment and hydrocracking catalysts including production of the catalyst components (amorphous aluminosilicates, zeolites) are in progress now.

CoNiMo/Al2O3 catalysts for deep hydrotreatment of vacuum gasoil

Trimetallic Co-Ni-Mo catalysts with different Co and Ni content (Co3Ni0, Co1.8Ni1.2, Co1.5Ni1.5, Co1.2Ni1.8 and Co0Ni3) were studied. Catalysts were characterized by HRTEM, XPS, EXAFS and XANES methods. It was shown that all catalysts contain metals preferentially in the form of sulfide active component with the structure that is similar to Co-Mo-S phase. Co-Mo and Ni-Mo catalysts contain active component in the form of Co-Mo-S and Ni-Mo-S phases respectively. Trimetallic catalysts were shown to contain mixed Ni-Co-Mo-S phases. Catalytic tests showed that the catalyst with 1.8% Co, 1.2% Ni and 10% Mo has the highest activity in hydrotreating of VGO. The highest activity of the catalyst is proposed to be provided by the formation of mixed Ni-Co-Mo-S phase.

A new catalyst for the deep hydrotreatment of vacuum gas oil, a catalytic cracking feedstock

A new CoNiMo/Al2O3 deep vacuum gas oil hydrotreatment catalyst designed for the production of catalytic cracking feedstocks containing 200–500 ppm of sulfur is developed. The method for its preparation includes the following stages: the preparation of a support with specified textural, strength, and granulometric characteristics; the synthesis of bimetallic (Co-Mo and Ni-Mo) complex compounds in solution; and their deposition and drying. The new sample is compared to current domestic and imported industrial analogs according to their physicochemical (texture, morphology, active phase structure) and catalytic characteristics and analyzed. It is shown that the catalyst allows hydrotreatment at temperatures 5–20°C lower and target fraction yields 4–13% higher than all the reference samples. The high activity of the new catalyst is due to the formation of one-layer trimetallic Co(Ni)MoS phase particles at the stage of its sulfidation. The catalyst preparation technique is ready for industrial use (OOO Sintez, Barnaul, 1000 t/yr), and the principal technological regimes of the hydrotreatment of vacuum gas oil on the developed catalyst are determined.

Dealing with uncertainties: Sensitivity analysis of vacuum gas oil hydrotreatment

This work applies sensitivity analysis to a kinetic model of hydrotreating processes. The proposed approach is subdivided into several steps: The first step is to build the kinetic model. The second step is to develop a simplified model (meta model) on which easy calculations can be performed in the next step. The third step is to use the meta model to estimate the influence of each input on the model output without Monte Carlo methods which are difficult to manage. Sensitivity analyses are very useful for model comparison and uncertainties estimation.

Kinetic Modeling of Vacuum Gas Oil Hydrotreatment using a Molecular Reconstruction Approach

Vacuum Gas Oils (VGO) are heavy petroleum cuts (boiling points ranging from 350 to 550 ˚C) that can be transformed into valuable fuels (gasolines, diesels) by fluid catalytic cracking or hydrocracking. Prior to these conversion processes, hydrotreating is required in order to eliminate the impurities in VGOs. The hydrotreatment process enables to meet the environmental specifications (total sulfur contents) and to prevent nitrogen poisoning of conversion catalysts. In order to develop a kinetic model based on an accurate VGOs molecular description, innovative analytical tools and molecular reconstruction techniques were used in this work. A lumped model using a Langmuir-Hinshelwood representation was developed for hydrodearomatization, hydrodesulfurization and hydrodenitrogenation of the VGO. This lumped model was successfully applied to the experimental feed pretreatment data and was able to predict evolution of concentration of the aromatics, nitrogen and sulfur species.

Oxidative Regeneration of Spent Molybdate and Tungstate Hydrotreating Catalysts

Temperature-programmed oxidation of NiMo, CoMo and NiW hydrotreating catalysts from hydrotreatment of vacuum gas oil and coal-derived oils was carried out in thermogravimetric and fixed-bed reactors. Attempts were made to elucidate the mechanism of oxidative removal of carbon and sulfur from spent catalysts, and to investigate the structural changes of active metals and some solid-phase interactions between active metals and deposited metals during regeneration in order to correlate these resulting properties with the catalytic activities of regenerated catalysts. Changes in chemical states and structure of supported metals were analyzed by EXAFS and XPS. These structural changes were also analyzed by using the thermodynamical phase diagrams. This talk will discuss the differences in the oxidative regeneration severity between Mo and W spent catalysts, structural changes of supported metals during oxidation and following sulfidation, and effectiveness of the thermodynamics to predict a priori the regeneration and following sulfidation behavior.

New developments in hydrocracking: low pressure high-conversion hydrocracking.

Hydrogen partial pressure is a key parameter for distillate hydrocracking processes. There are two types of distillate hydrocracking processes. Mild hydrocracking is an improved vacuum gas oil hydrotreatment process with a relatively low conversion, which operates at hydrogen pressures usually less than 50 bars. Total conversion hydrocracking operates at hydrogen pressures of more than 100 bars. It is thus obvious that hydrogen pressure is a key parameter for hydrocracking performances. By looking at the different reactions taking place in the hydrocracking process, we try to explain this effect from thermodynamic and kinetic standpoints. For instance the hydroconversion of n-heptane has a negative order with respect to hydrogen pressure, when this order is positive for the conversion of a vacuum gas oil. We present pilot data showing the great influence of a first step hydrotreatment of a VGO on the second hydrocracking step. We demonstrate also the possibility of achieving very high conversion when operating at “medium pressure” (i.e. around 70 bars) with a recently developed zeolite hydrocracking catalyst.