Process and Catalyst Needs for Hydrodenitrogenation

Hydrogenation of Pyridine and Hydrogenolysis of Piperidine overγ-Mo2N Catalyst: A DFT study

Increasing demands on producing environmentally friendly products are becoming a driving force for designing high active catalysts. Thus, surfaces that efficiently catalyse the nitrogen reduction reactions are vastly sought in moderating air-pollutant emissions. This contribution aims to computationally investigate the hydrodenitrogenation (HDN) networks of pyridine over γ-Mo2N(111) surface via density functional theory (DFT) approach. Various adsorption configurations have been considered for the molecularly adsorbed pyridine. Findings indicate that pyridine can be adsorbed via side-on and end-on modes in six geometries in which one adsorption site is revealed to have the lowest adsorption energy of (-45.3 kcal/mol(. Over nitrogen hollow site adsorption site, initial HDN steps proceed by the stepwise hydrogenation of pyridine into piperidine followed the Langmuir−Hinshelwood mechanism. The obtained findings are the first to theoretically model the hydrogenation pathways of pyridine to form piperidine then the hydrogenolysis of piperidine producing C5H12 and NH3 over metal nitride and paved the way for further investigations to better understanding such an important nitrogen removal reactions.

Comparison of Moving-Bed Catalytic Tar Hydrocracking Processes

In recent years, there has been a trend in the global oil industry to improve the proportion of heavy high-sulfur crude oils in the total volume of extracted and processed resources, reserves of which are estimated at over 800 billion metric tons. Therefore, the main line of oil refining is processing of heavy crudes and residua to allow maximum use of the hydrocarbon potential and yield of high-margin products. Hydrogenation processes of heavy raw materials are most attractive in terms of product quality. This article analyzes tar hydrocracking processes that are either in operation or at the stage of full-scale testing. These include Veba Combi-Cracker (VCC), Uniflex, suspended-bed catalyst hydrocracking (ENI), and vacuum residue hydroconversion (TIPS RAS). These technologies use heterogeneous catalysts and are designed to obtain the largest possible amount of liquid products. This article discusses the features of each technology, highlights their advantages and disadvantages, shows the main approaches to process management, and speculates about the development of these technologies. Tar refining is a major process in heavy oil upgrading, and the development of efficient tar-processing methods will influence refinery configurations and management.

How to select ionic liquids as extracting agents systematically: a special case study for extractive denitrification processes

Extractive denitrification (EDN) of shale oil using ionic liquids (ILs) as the extracting agent has good industrial prospects.

Specification of the nitrogen functional group in a hydrotreated petroleum molecule using hydrogen/deuterium exchange electrospray ionization high-resolution mass spectrometry

Hydrotreatment is extensively used for the production of clean fuel. Attaining an understanding of the structural conversion of the nitrogen species during hydrotreatment is very challenging due to the compositional complexity and the absence of a proper characterization method. In the presented work, we coupled hydrogen/deuterium exchange (HDX) with positive-ion electrospray ionization high-resolution mass spectrometry ((+) ESI HR MS) to investigate the difference between the composition of the nitrogen-containing species and the functional groups before and after hydrotreatment. The solvent and additive were optimized for HDX (+) ESI HRMS through systematic evaluations on model nitrogen-containing compounds. We found that adding deuterated water (D₂O) and deuterated formic acid (DCOOD) significantly increased the degree of HDX and thus facilitated the identification of nitrogen functional groups. After application to the hydrotreated petroleum samples, the compositional variation of intermediate amine compounds during the heavy petroleum hydrotreatment process was clearly revealed.

Ultrasound-assisted oxidative desulfurization and denitrogenation of liquid hydrocarbon fuels: A critical review

Nowadays, a continuously worldwide concern for development of process to produce ultra-low sulfur and nitrogen fuels have been emerged. Typical hydrodesulfurization and hydrodenitrogenation technology deals with important difficulties such as high pressure and temperature operating condition, failure to treat some recalcitrant compounds and limitations to meet the stringent environmental regulations. In contrary an advanced oxidation process that is ultrasound assisted oxidative desulfurization and denitrogenation satisfies latest environmental regulations in much milder conditions with more efficiency. The present work deals with a comprehensive review on findings and development in the ultrasound assisted oxidative desulfurization and denitrogenation (UAOD) during the last decades. The role of individual parameters namely temperature, residence time, ultrasound power and frequency, pH, initial concentration and types of sulfur and nitrogen compounds on the efficiency are described. What's more another treatment properties that is role of phase transfer agent (PTA) and solvents of extraction step, reaction kinetics, mechanism of the ultrasound, fuel properties and recovery in UAOD are reviewed. Finally, the required future works to mature this technology are suggested.

Hydrodenitrogenation of pyridines and quinolines at a multinuclear titanium hydride framework

Investigation of the hydrodenitrogenation (HDN) of aromatic N-heterocycles such as pyridines and quinolines at the molecular level is of fundamental interest and practical importance, as this transformation is essential in the industrial petroleum refining on solid catalysts. Here, we report the HDN of pyridines and quinolines by a molecular trinuclear titanium polyhydride complex. Experimental and computational studies reveal that the denitrogenation of a pyridine or quinoline ring is easier than the ring-opening reaction at the trinuclear titanium hydride framework, which is in sharp contrast with what has been reported previously. Hydrolysis of the pyridine-derived nitrogen-free hydrocarbon skeleton at the titanium framework with H2O leads to recyclization to afford cyclopentadiene with the generation of ammonia, while treatment with HCl gives the corresponding linear hydrocarbon products and ammonium chloride. This work has provides insights into the mechanistic aspects of the hydrodenitrogenation of an aromatic N-heterocycle at the molecular level.

Adsorption of Tungsten on Alumina from Sodium Tungstate Solutions. Estimation of Equilibrium and Kinetic Parameters

The tungsten adsorption isotherm from aqueous solutions of sodium tungstate on to alumina at 20°C has been studied. The isotherm shape was in agreement with that predicted by the classic Langmuir equation. This model was therefore fitted to the experimental data in order to determine the adsorption equilibrium constant and the total concentration of adsorption sites.

Kinetic parameters of adsorption were also determined. To do so, a theoretical model that predicts the tungsten concentration profiles in impregnated thin layers was fitted to the experimental profiles.

The diffuse reflectance spectra of dried samples used for isotherm determination and of thin alumina layers impregnated with tungsten solutions exhibit a band at 215 nm which is accompanied by a shoulder at 250 nm. For samples having a greater tungsten concentration, the shoulder develops and then transforms into a second band. The maximum at the lowest wavelength (first maximum) is assumed to correspond to tungsten in a tetrahedral coordination (monomeric species) while the second maximum is due to distortion in the tetrahedral symmetry caused by strong interactions between the support and the monomeric species.

Adsorption and Impregnation of Alumina with Molybdenum or Tungsten Solutions

The equilibrium parameters of molybdenum and tungsten adsorption on alumina were compared. Adsorptions were performed from aqueous solutions of monomeric or polymeric ions of these elements. For all solutions tested, molybdenum showed a greater affinity for alumina than tungsten. Assuming a pore-filling impregnation of alumina spheres, a model that interprets this process was used for the calculation of theoretical profiles which showed a smooth decrease in concentration along the sphere radius. In turn, the experimental profiles were similar to those predicted for impregnations with solutions of heptameric molybdate, monomeric molybdate and monomeric tungstate. For polymeric tungstate, however, the experimental tungsten concentration rapidly fell to zero near the sphere surface. Using diffuse reflectance spectroscopy, it was observed that the molybdenum was in tetrahedral and octahedral coordination in spheres impregnated with polymeric or monomeric molybdenum solutions; in addition, the ratio of the concentrations of these species was approximately the same. The species observed in spheres impregnated with tungsten solutions was monomeric tungstate, indicating a distortion in tetrahedral symmetry as a consequence of interaction with the alumina.

Adsorptive desulfurization and denitrogenation using metal-organic frameworks

With the increasing worldwide demand for energy, utilization of fossil fuels is increasing proportionally. Additionally, new and unconventional energy sources are also being utilized at an increasing rate day-by-day. These sources, along with some industrial processes, result in the exposal of several sulfur- and nitrogen-containing compounds (SCCs and NCCs, respectively) to the environment, and the exposure is one of the greatest environmental threats in the recent years. Although, several methods were established for the removal of these pollutants during the last few decades, recent advancements in adsorptive desulfurization and denitrogenation (ADS and ADN, respectively) with metal-organic frameworks (MOFs) make this the most promising and remarkable method. Therefore, many research groups are currently involved with ADS and ADN with MOFs, and the results are improving gradually by modifying the MOF adsorbents according to several specific adsorption mechanisms. In this review, ADS and ADN studies are thoroughly discussed for both liquid-phase and gas-phase adsorption. The MOF modification procedures, which are important for improved adsorption, are also described. To improve the knowledge among the scientific community, it is very important to understand the detailed chemistry and mechanism involved in a chemical process, which also creates the possibility and pathway for further developments in research and applications. Therefore, the mechanisms related to the adsorption procedures are also discussed in detail. From this review, it can be expected that the scientific community will obtain an understanding of the current state of ADS and ADN, their importance, and some encouragement and insight to take the research knowledge base to a higher level.

A study on the origin of the active sites of HDN catalysts using alumina-supported MoS3 nanoparticles as a precursor

The origin of the active sites of the hydrodenitrogenation catalysts was comprehensively studied using alumina-supported MoS₃ nanoparticles (NPs) as a novel precursor.

Extractive denitrogenation of fuel oils using ionic liquids: a review

Extractive denitrogenation (EDN) of fuel oils using ILs is reviewed. EDN using ILs is a promising technology for the elimination of N-compounds from fuel oils.

Selective removal of isoquinoline and quinoline from simulated fuel using 1,1′-binaphthyl-2,2′-diol (BINOL): crystal structure and evaluation of the adduct electronic properties

1,1′-Binaphthyl-2,2′-diol/quinoline (BINOL/QUN) and 1,1′-binaphthyl-2,2′-diol/isoquinoline (BINOL/ISOQUN) adducts were successfully synthesized. Isothermal titration calorimetry (ITC) involving 1,1′-binaphthyl-2,2′-diol (BINOL) and isoquinoline confirming interaction.

Adsorption of indole and quinoline from a model fuel on functionalized MIL-101: effects of H-bonding and coordination

Adsorptive denitrogenation was carried out with functionalized metal–organic frameworks in order to understand plausible adsorption mechanisms.

Initial hydrogenations of pyridine on MoP(001): a density functional study

The initial hydrogenations of pyridine on MoP(001) with various hydrogen species are studied using self-consistent periodic density functional theory (DFT). The possible surface hydrogen species are examined by studying interaction of H(2) and H(2)S with the surface, and the results suggest that the rational hydrogen source for pyridine hydrogenations should be surface hydrogen atoms, followed by adsorbed H(2)S and SH. On MoP(001), pyridine has two types of adsorption modes, i.e., side-on and end-on; and the most stable η(5)(N,C(α),C(β),C(β),C(α)) configuration of the side-on mode facilitates the hydrogenation of pyridine. The optimal hydrogenation path of pyridine with surface hydrogen atoms in the Langmuir-Hinshelwood mechanism is the formation of 3-monohydropyridine, followed by producing 3,5-dihydropyridine, in which the two-step hydrogenations take place on the C(β) atoms. When adsorbed H(2)S is considered as the source of hydrogen, slightly higher hydrogenation barriers are always involved, while the energy barriers for hydrogenations involving adsorbed SH are much lower. However, the hydrogenation of pyridine should be suppressed by the adsorption of H(2)S, and the promotion effect of adsorbed SH is limited.