Higher Hydrodenitrogenation Activity Research Articles

Understanding the effects of feedstock blending and catalyst support on hydrotreatment of algae HTL biocrude with non-edible vegetable oil

The performance of cobalt-molybdenum (CoMo) on hydrotreating of algae HTL biocrude and carinata oil was investigated. Commercial CoMo/Al2O3 (CoMo/Al) and synthesized CoMo supported on Douglas fir biochar (CoMo/DF), sulfided or unsulfided catalysts, were compared for hydrodeoxygenation (HDO), hydrodenitrogenation (HDN), hydrodesulfurization (HDS) and hydrodemetallization (HDM) reactions. Results showed that there lies a synergistic effect when HTL algae biocrude and carinata oil blends are hydrotreated. The yield of the upgraded blend (UB) oils retrieved over alumina catalyst was higher than the individual hydrotreated parent oils. For example, a 9% and 5% increase in yield was noted compared to the average of individual hydrotreated parent oils. The UB produced from sulfided CoMo/Al exhibited superior HDO activity primarily by decarbonylation. This was apparent in increased heating value, carbon addition, higher octane number, and lower total acid number than the oils obtained from the biochar-supported catalysts. Sulfided CoMo/DF catalyzed cracking reactions which lowered the viscosity, followed by high HDN and HDS activity compared to the commercial catalyst. The two supports showed different sorption behaviors. Interestingly, CoMo/DF had an effective sorption mechanism that helped in higher metal removal from the oil. Additionally, presulfiding and DF support exhibited positive results in term of less coke formation. In brief, biochar supports have higher acidic sites, inorganic mineral oxides, ion exchange capacity, high surface area, pore structure and connectivity. All of these make a substantial contribution to its unique catalytic behavior.

A detailed investigation on rhenium loaded SBA-15 supported catalyst for hydrodenitrogenation reaction of cyclohexylamine

The present work is aiming to utilize Re based catalysts for hydrodenitrogenation (HDN) of cyclohexylamine over SBA-15 supported catalyst under optimized conditions. Siliceous SBA-15 was synthesized by hydrothermal method and used as a support for Re catalysts with different Re loadings (1, 3, 5 and 7 wt%). The supported catalysts were characterized by various physico-chemical techniques like XRD, N2-sorption studies, UV-DRS, FE-SEM, HR-TEM, NH3-TPD, Raman spectroscopy and XPS (sulfided catalyst). The oxide catalysts were presulfided before the hydrodenitrogenation reaction using ditertiary butyl polysulfide (DBPS) as sulfiding agent and hydrogen. The catalytic activity of the sulfided catalysts was tested for HDN of cyclohexylamine. A high HDN activity was observed on 5 wt% Re loaded SBA-15 catalyst. The catalytic activity was correlated with characterization results.

Quinoline Hydrodenitrogenation over NiW/Al-MCM-41 Catalysts with Different Al Contents

Al-MCM-41 materials were prepared with different Al contents and used as supports for NiW catalysts. The supports and catalysts were characterized by XRD, N2 adsorption-desorption, XPS, Raman, H2-TPR techniques. The XPS result showed that the Al added to MCM-41 promoted the dispersion of W and Ni species. The Raman result showed that the Al added to MCM-41 favored the formation of the suitable W species. The H2-TPR result showed that the Al added to MCM-41 can reduce the reduction temperature of W species on the catalysts. The hydrodenitrogenation (HDN) results showed that the HDN activity followed the order of NiW/Al-2 > NiW/Al-1 > NiW/Al-4 > NiW. Moreover, this tendency was also valid for the ratio of propylcyclohexane/propylbenzene (PCH/PB). The high HDN activity and PCH/PB ratio of NiW/Al-2 are due to the well dispersion of the W and Ni species, the suitable W species and the low reduction temperature of W species.

Preparation and characterization of NiW supported on Al-modified MCM-48 catalyst and its high hydrodenitrogenation activity and stability

Al-containing MCM-48 with different Si/Al ratios and aluminum free MCM-48 materials were successfully prepared with CTAB and P123 as a co-template.

MCM-41 Supports Modified by Al, Zr and Ti for NiW Hydrodenitrogenation Catalysts

MCM-41 materials modified by Al, Zr and Ti were used as supports for the preparation of the NiW hydrodenitrogenation (HDN) catalysts. The modified supports, with highly dispersed Al, Zr and Ti species and without loss of the MCM-41 characteristics, can be prepared by a postsynthetic method. The incorporation of Al, Zr and Ti can enhance the density of acid sites on the modified MCM-41, so as to increase the density of acid sites and even enhance the dispersion of Ni, W species on the corresponding catalysts. The HDN results showed that the incorporation of Al, Zr and Ti can increase the HDN activity of the catalysts and the activity followed the order of Ni/W/Al > Ni/W/Zr > Ni/W/Ti > Ni/W. The high HDN activity of Ni/W/Al ascribed to the high density of acid sites and the well dispersion of the Ni and W species on the catalyst.

Hydrodenitrogenation of Basic and Non-Basic Nitrogen Compounds in Shale Oil over NiW/Al<sub>2</sub>O<sub>3</sub> Catalyst

The hydrodenitrogenation (HDN) of Longkou shale oil were carried out in microscale trick-bed reactor over a commercial NiW/Al2O3 catalyst with high HDN activity. The effects of temperature, pressure, liquid hourly space velocity (LHSV) and hydrogen/oil ratio on the conversions of total, basic and non-basic nitrogen compounds were investigated at various conditions (340-420°C, 0.2-2h-1, 4-9MPa and 400-1000 L/L). The results show that basic nitrogen compounds have higher HDN reactivity than non-basic nitrogen. The distributions and species of nitrogen compounds in Longkou shale oil were also investigated. About 33% of total nitrogen is present in big molecules with high boiling point. The nitrogen compounds in Longkou shale oil are mainly composed by seven kinds of components ( nitriles, anilines, pyridines, quinolines, acridines, carbazoles and indoles).

Preparation and evaluation of hydrotreating catalysts based on activated carbon derived from oil sand petroleum coke

Novel Ni–Mo/activated carbon (AC) hydrotreating catalysts were prepared and evaluated for upgrading heavy vacuum gas oil (HVGO). The AC supports were derived from Alberta oil sand petroleum coke, i.e. fluid coke and/or delayed coke, hereafter referred to as OSP coke, through a chemical process. The BET surface area was as high as 2194m2/g for the fluid coke derived AC and 2357m2/g for the delayed coke derived AC. Both ACs contained a large number of micropores with pore volume as high as 1.2cm3/g. Ni and Mo based active component precursors could be easily loaded on the activated carbon supports by chemical impregnation of nickel nitrate and ammonium molybdate followed by calcination in nitrogen at 773K without further modification or oxidation treatment to the activated carbons. Scanning electron microscopy (SEM) observation showed highly porous surface structure of the bare activated carbon supports and well dispersed metal (oxide) precursor nanoparticles of 30–50nm loaded on the AC supports. For comparison, two reference catalysts were also prepared by the same procedure but using commercial activated carbon and porous alumina as supports. After catalyst activation by sulfiding, the hydrotreating performance of the prepared catalysts was evaluated in a magnetically stirred autoclave with a HVGO feedstock to examine their hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. Two commercial hydrotreating catalysts were also tested and compared under similar conditions with the same feed. The results showed that the catalysts based on the activated carbon supports prepared from OSP coke had better hydrotreating performance than the other catalysts. Scanning transmission electron microscopy (STEM) characterization of the catalysts after activation showed that small particles of nanostructure (2–5nm in size) were evenly embedded in the carbon matrix except for some bigger particles that were located on the catalyst surface. Energy dispersive X-ray (EDX) spectroscopy revealed that these particles were composed of Ni, Mo and S elements. The dispersed nanoparticles formed the active sites and were responsible for the observed high HDS and HDN activity. Elemental analysis and surface characterization of the spent catalysts showed that the formation of coke precursors was favored on the alumina supported catalyst, which resulted in catalyst deactivation.

Effect of phosphorus content on the active phase structure of NiMoP/Al2O3 catalyst

NiMoP/Al2O3 catalysts with different phosphorus contents were prepared by co-impregnation method and are characterized by temperature-programmed reduction (TPR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) tests. The effect of phosphorus content on the active phase structure of these catalysts was investigated. The TPR results indicated that with the increase of the phosphorus content in the catalysts, the amount of tetrahedral Mo species was decreased, while that of octahedral Mo species was increased. The HRTEM results showed that the number of stacking layers of MoS2 nanoparticles increased with the phosphorus content, which was effective in enhancing the hydrogenation selectivity of the catalysts. The fraction of available Mo dispersion (fMo) and the number of active phases in the catalysts increased with increasing phosphorus content to P/MoO3 = 0.09; beyond that, a reverse trend was observed. High HDS and HDN activity were obtained over the catalyst with the phosphorus content of P/MoO3 = 0.09, which could be attributed to its high concentration of Mo atoms on the catalyst surface, high-efficient promotion rate (PR) and high promoter ratio (Ni/Mo). However, excessive phosphorus content may deteriorate the performance of NiMoP/Al2O3 catalysts due to the aggregation of active components.

Effect of Order of Impregnation of Mo and Ni on the Hydrodenitrogenation Activity of NiO-MoO3/AlMCM-41 Catalyst

The influence of order of the impregnation of NiO and MoO3 on the structure and catalytic behavior of H-AlMCM-41 supported Ni−Mo catalysts for hydrodenitrogenation (HDN) has been investigated. These catalysts were well characterized by TEM, XRD, N2 adsorption−desorption, XPS, and FT-IR spectra of CO adsorption and tested for hydrodenitrogenation (HDN) of o-toluidine and cyclohexylamine. It was found that the catalyst prepared by sequential impregnation of NiO and MoO3 was more active than the catalyst prepared by coimpregnation. Among the sequentially impregnated catalysts, the catalyst in which NiO deposited first followed by MoO3 shows high HDN activity. TEM, FT-IR spectra of CO adsorption, and estimation of total sulfur of sulfide catalyst results clearly show that the NiO and MoO3 are well dispersed over H-AlMCM-41 on reverse order impregnated catalyst. The very low activity of coimpregnated catalyst is attributed to poor dispersion of metal oxides as well as due to the formation of stable stoichiometric oxide and aggregates of metal particle over the support surface.

Mesoporous silica–alumina as support for Pt and Pt–Mo sulfide catalysts: Effect of Pt loading on activity and selectivity in HDS and HDN of model compounds

The potential of mesoporous silica–alumina (MSA) material as support for the preparation of sulfided Pt and Pt–Mo catalysts of varying Pt loadings was studied. The catalysts were characterized by their texture, hydrogen adsorption, transmission electron microscopy, temperature programmed reduction (TPR) and by activity in simultaneous hydrodesulfurization (HDS) of thiophene and hydrodenitrogenation (HDN) of pyridine. Sulfided Pt/MSA catalysts with 1.3 and 2wt.% Pt showed almost the same HDS and higher HDN activities per weight amounts as conventional CoMo and NiMo/Al2O3, respectively. The addition of Pt to sulfided Mo/MSA led to promotion in HDS and HDN with an optimal promoter content close to 0.5wt.%. The results of TPR showed strong positive effect of Pt on reducibility of the MoS2 phase which obviously reflects in higher activity of the promoted catalysts. The activity of the MSA-supported Pt–Mo catalyst containing 0.5wt.% Pt was significantly higher than the activity of alumina-supported Pt–Mo catalyst. Generally, Pt–Mo/MSA catalysts promoted by 0.3–2.3wt.% Pt showed lower HDS and much higher HDN activities as compared to weight amounts of CoMo and NiMo/Al2O3. It is proposed that thiophene HDS and pyridine hydrogenation proceed over Pt/MSA and the majority of Pt–Mo/MSA catalysts on the same type of catalytic sites, which are associated with sulfided Pt and MoS2 phases. On the contrary, piperidine hydrogenolysis takes place on different sites, most likely on metallic Pt fraction or sites created by abstraction of sulfur from MoS2 in the presence of Pt.

Hydrodenitrogenation of Quinoline Catalyzed by MCM-41-Supported Nickel Phosphides

A series of MCM-41-supported nickel phosphides with an initial Ni/P atomic ratio of 0.5−2 in the oxidic precursors were prepared by an in situ reduction method and characterized by X-ray diffraction (XRD), CO chemisorption, N2 adsorption, and transmission electron microscopy. Their catalytic performances were evaluated in the hydrodenitrogenation (HDN) of quinoline and compared with MCM-41-supported Ni−Mo sulfide. The supported nickel phosphides with initial Ni/P ratios of 1 or 1.25 exhibited much higher HDN activity than the supported Ni−Mo sulfide. XRD patterns of both high-performance phosphide catalysts revealed that the active phase was Ni2P. It is indicated that the HDN of quinoline on the MCM-41-supported nickel phosphides exclusively proceeds via a pathway, which involves fully saturated intermediates. The cleavage of the C−N bond in the decahydroquinoline is the rate-determining step in the HDN of quinoline on the supported nickel phosphides. In addition, the effects of H2S (CS2 as the precursor)...

Performance Evaluation of Certain Commercial Hydrotreating Catalysts in a Pilot Plant Reactor

The performance of different hydrotreating catalysts was evaluated in a pilot plant trickle bed reactor using a feedstock collected from an industrial diesel hydrodesulfurization unit. The feed is a typical blend of straight run diesel fractions from crude distillation units, FCC cycle oils, heavy naphtha, etc. It contains 1.11 wt% of sulfur, 0.12 wt% of nitrogen, and 34.6 wt% of total aromatics. The catalyst samples evaluated in the present work are commercially available high activity new generation catalysts being used in many refineries for diesel hydrodesulfurization application. The experiments were carried out at a constant pressure of 40 kg/cm2 and a constant H2/oil ratio of 200 l/l. Experiments were performed to study the influence of reactor temperature and liquid hourly space velocity on product quality. The reactor temperature was varied from 320–360°C at different liquid hourly space velocities. The liquid hourly space velocity was varied from 1.0 to 2.5 h−1 at different reactor temperatures. The feed and product samples hydrotreated in the pilot plant reactor were analyzed to determine their physical properties and measure sulfur, nitrogen, olefinic, poly-, di-, monoaromatic, and naphthenic hydrocarbons. Catalyst C was found to have the highest hydrodesulfurization activity among the catalysts studied. The hydrodesulfurization activity of catalyst A and catalyst B are similar. Catalyst D was found to have lower hydrodesulfurization and higher hydrodenitrogenation activity compared to catalyst C.

The effect of boron addition on hydrodesulfurization and hydrodenitrogenation activity of NiMo/Al 2O 3 catalysts

Studies of catalytic activity of a series of nickel–molybdenum catalysts supported on Al 2O 3 modified with borate ions were performed for the hydrotreating of coal liquid. Decomposition of isopropyl alcohol, diacetone alcohol and ethylbenzene was performed for the characterization of acidity of the catalysts. Quinoline and carbazole hydrodenitrogenation (HDN) were used as test reactions. It was found that modification of the support with borate ions increases the acidity of nickel–molybdenum catalyst, in particular, the amount of acidity centers of intermediate strength. However, although the modification practically does not affect the hydrosulfurization activity of coal liquid, it considerably affects its HDN activity. In the latter case, it leads to an increase in the resistance to coking of the modified catalysts. This particularly applies to the HDN process in which the above catalysts are still very active after a long period of run, and hence their dehydrogenation activity rises. The high HDN activity is connected to the increasing number of acid centers of intermediate strength.

Hydrodenitrogenation of pyridine over alumina-supported iridium catalysts

The catalytic properties of alumina-supported Ir catalysts (≈1 wt% Ir) were studied in the hydrodenitrogenation (HDN) of pyridine at 320°C and 20 bar of pressure in the absence as well as presence of parallel hydrodesulfurization (HDS) of thiophene. The effects of Ir precursor (Ir(AcAc) 3, Ir 4(CO) 12, H 2IrCl 6, (NH 4) 2IrCl 6), metal dispersion and sulfur addition were investigated. Ir 4(CO) 12 gave the most active catalyst which was ascribed to a lower amount of contaminants originated from the starting Ir compounds rather than to a better Ir dispersion. The decrease of Ir dispersion by sintering in air led to much higher decrease of the rate of C–N bond hydrogenolysis than that of pyridine hydrogenation. The Ir dispersion determined partly the HDN selectivity; a better dispersed Ir phase gave a lower amount of intermediate piperidine. Presulfidation of the reduced catalyst led to 20% decline of the rates of both consecutive HDN steps. An additional and much larger activity decline was caused by the simultaneous execution of HDS. The competitive adsorption of thiophene (or H 2S) was selectively affecting C–N bond hydrogenolysis more than pyridine hydrogenation. The alumina-supported Ir catalysts possessed much higher HDN activity and HDN/HDS selectivity than a conventional NiMo system.

Carbon supported Ni-Mo catalyst: high hydrodenitrogenation activity and low inhibition of hydrodesulphurization by hydrodenitrogenation

Four active carbon supported Ni-Mo sulphide catalysts and alumina supported Ni-Mo catalyst Shell 324 were tested in concurrent hydrodesulphurization (HDS) of thiophene and hydrodenitrogenation (HDN) of pyridine at 2 MPa and 280 °C. The various Ni-Mo/C catalysts differed in the pretreatment of the support which was extracted by various solvents before impregnation. The data were also compared with previous results on the same catalysts in HDS of thiophene in the absence of pyridine. The HDN activity of the Ni-Mo/C catalysts was three to five times higher than that of the reference Shell catalyst. The inhibition of HDS by HDN was much lower on the Ni-Mo/C than on the Ni-Mo/alumina samples. Consequently, HDS activity of the Ni-Mo/C catalysts in the presence of pyridine was very high, the best catalyst being 14 times more active than the alumina supported sample.

Comparison of carbon and alumina supported nickel—molybdenum sulphide catalysts in parallel hydrodenitrogenation and hydrodesulphurisation

The catalytic properties of Ni—Mo/C and Ni—Mo/Al 2O 3 sulphide catalysts were compared in the hydrodesulphurisation of thiophene and in parallel hydrodesulphurisation of thiophene and hydrodenitrogenation of pyridine. The carbon support used was based on carbon black. The special features of carbon-supported catalysts are their high resistance during the hydrodesulphurisation activity to poisoning by pyridine, high hydrodenitrogenation activity and high hydrodesulphurisation/hydrodenitrogenation selectivity.