Hydrodesulphurization Catalysts Research Articles

Study on fluidized roasting of spent hydrodesulphurisation catalysts in large-scale industrial boiling furnace by CFD simulation

When the valuable metals in the hydrodesulphurisation (HDS) catalysts are recovered by the pyrometallurgical process, the traditional roasting method is prone to the problem of insufficient oxidative conversion of metal sulfides. However, the residual oil and carbon in the spent HDS catalysts cannot be effectively utilized, resulting in additional energy consumption. Fluidized roasting in a boiling furnace is a good way to use residual oil and carbon to provide heat for roasting while oxidizing the metal sulfides in the spent HDS catalyst. This study used computational fluid dynamics (CFD) coupled with the Coarse-Graining model (CGM) to simulate the fluidized roasting effect of HDS catalysts at different initial bed heights and gas velocities in a large-scale industrial boiling furnace. To improve the fluidized roasting quality and reduce the energy consumption, it is recommended that the optimal initial bed height (H0) is 0.45 m, the gas velocity (ug) is 1.45 m/s. The gas consumption and the net energy saving were 0.34 m3/kg and 2.29 × 1010J under this condition. Accordingly, the theory of the competitive relationship between particle collision and bubble fragmentation is innovatively proposed, and the distribution change of the turbulent energy intensity zone verifies this theory.

A kinetic approach for valorisation of hydrodesulphurisation catalyst residue into mullite

Mullite (3Al2O3·2SiO2) is a silicoaluminate widely used for the production of ceramics, and it is usually synthesised from different raw materials with solid-state reactions. In this work, petrochemical industry catalyst waste (Ni–Mo waste) composed principally of alumina and silica has been envisaged as a suitable precursor to prepare mullite via thermal treatment. The kinetics of mullite crystallisation from the catalyst waste were studied with differential thermal analysis (DTA). The starting Ni–Mo waste was an amorphous material, and the crystallisation process takes place at temperatures between 1200 and 1300 °C. The activation energies calculated with isothermal and nonisothermal methods were 1059 and 743 kJ mol-1, respectively. The Avrami exponent (n) obtained with the Ligero method and the parameter m calculated with the Matusita method indicated two-dimensional crystal growth, probably through a diffusion-controlled bulk crystallisation mechanism from a constant number of nuclei. The frequency factor calculated by the isothermal treatment was 8 x 1033 s-1.

Metal recovery from spent Ni-Mo-V hydrodesulphurisation catalyst in oxalic acid media by mechanochemical treatment

ABSTRACT The spent hydrodesulphurisation (HDS) catalysts used for the removal of sulphur from petroleum products can be a secondary source of especially Mo and V. This work describes the mechanochemical extraction of Mo, Ni, V, Al and P from spent petrochemical catalysts in H2C2O4. The effect of rotational speed, H2C2O4 concentration, ball to the dust weight ratio and solid-to-liquid ratio on the extraction rate of roasted spent catalyst was investigated. The reactions proceed with an increase in H2C2O4 concentration for extraction of Mo, V and P. The reactions for the extraction of Mo, V and P proceed with an increase in H2C2O4 concentration, but the dissolution behaviour of Ni is different from other elements. 87% of Mo, 44% of Ni, 82% of V, 36% of Al and 78% of P were extracted at optimum experimental conditions.

A feasibility study for a circular approach in oil refining: Metals recovery from hydrodesulphurization catalysts

The paper deals with a profitability analysis developed for a plant that recycles spent hydrodesulphurization (HDS) catalysts. Such catalysts contain molybdenum (Mo), nickel (Ni), and vanadium (V), supported by an alumina (Al2O3) carrier. The recycling process is based on a double thermal pre-treatment stage, followed by a series of hydrometallurgical steps that allow recovering Mo and V and a Ni concentrate that need further refining for separation and recovery of the metals.The economic analysis is based on the discounted cash flow method, and the baseline case analyses show that the net present value (NPV) is 14,877 thousand EUR. The selling price of vanadium pentoxide strongly influences the results. Alternative scenarios are also studied to strengthen the results obtained, considering the sensitivity, scenario and risk analyses. Profitability is confirmed in 87% of the considered scenarios, and in about 81.5%, the NPV of the baseline scenario is achieved. Circular economy models can be realized if products are recovered and if there are technologies that can recover metals. This study confirms that an example of a circular economy is met from the proposed viability analysis, and the economic benefits can be significant.

ADSORPTION STUDY OF HYDRODESULPHURIZATION CATALYST

Physical and chemical adsorption analyses were carried out by nitrogen gas using ASTM apparatus at 77 Kand hydrogen gas using volumetric apparatus at room temperature respectively. These analyses were used fordetermination the effect of coke deposition and poisoning metal on surface area, pore size distribution andmetal surface area of fresh and spent hydrodesulphurization catalyst Co-Mo\Al2O3 .Samples of catalyst (fresh and spent) used in this study are taken from AL-Dura refinery.The results of physical adsorption shows that surface area of spent catalyst reduced to third compare withfresh catalyst and these catalysts exhibit behavior of type four according to BET classification ,so, the poresof these samples are cylindrical, and the pores of fresh catalyst suffers during the hydrodesulphurization .The result of chemical adsorption shows that the metal surface area of fresh catalyst is 50.72 m2/g while itreduced to 39.04 m2/g for spent catalyst.

Self-circulation of oily spent hydrodesulphurization (HDS) catalyst by catalytic pyrolysis for high quality oil recovery

In this study, roasted spent HDS ash (sHDSc-A) was used for the first time to catalytically pyrolyze oily spent HDS catalysts (sHDSc) to improve the yield and quality of pyrolysis oil. The results showed that sHDSc-A promoted the decomposition of coke in oily sHDSc, resulting in the recovery of more oil and gas. Meanwhile, sHDSc-A significantly improved the quality of the pyrolysis oil. They inhibited the aromatization of alkanes to increase the saturation of the pyrolysis oil from 59.39% to 74.25% and the H/C radio from 1.62 to 1.72; promoted the decomposition of long-chain alkanes to increase the content of C11–C22 from 41.97% to 61.99%; enhanced the conversion of carboxylic acids to ketones led to the reduction of heteroatomic compounds such as N (56.10%–45.39%), S (66.95%–56.59%), and O (45.26%–26.70%) in the pyrolysis oil. The promotion of sHDSc-A in the pyrolysis process is attributed to the catalytic effect of the metal oxides in sHDSc-A. Among them, Al2O3 and Fe2O3 can promote decarboxylation of carboxylic acids and reduce O mobility, while MoO3 and Fe2O3 play a significant role in reducing coke and increasing pyrolysis oil. NiO can also promote methane vapor reforming, and thus increase the production of H2 in non-condensable gas. This study achieves self-circulation of oily sHDSc with a “waste-treatment-waste” strategy that presents the advantage of value-added energy recovery and waste reuse.

Pyrolysis Oils from Used Tires and Plastic Waste: A Comparison of a Co-Processing with Atmospheric Gas Oil

This study aimed to determine the effect of the supplied pyrolysis oils (oils obtained from the pyrolysis of used tyres and the depolymerisation of plastics) on the activity of the hydrodesulphurisation catalyst. Each pyrolysis oil was added at 20% weight to a standard feedstock and processed on pilot plant reactors under the set conditions of a commercial unit, including an activated catalyst. Following the catalyst stabilisation, the standard material was changed to the mixture with the pyrolysis oils. The reaction conditions, particularly the reaction temperature, were controlled. The results of the product analyses were compared with the EN 590 standard for evaluating diesel fuel; the hydrogenated mixed fuel meets most requirements. Only the density, flash point, distillation curve and lubricity have minor deviations, which could be adjusted by treating the sample before or after hydrogenation. The properties of the products, in terms of the low-temperature properties, were also investigated. The tyre-derived pyrolysis oils showed improved low-temperature properties, possibly due to the higher levels of the aromatic hydrocarbons. The pyrolysis oil obtained from the depolymerisation of the plastics was found to be more suitable for use in refineries without substantially impacting the existing technologies. For the tyre-derived pyrolysis oils, higher reaction temperatures were required for processing, which could affect the catalyst operation.

A fast and efficient method for the efficient recovery of crude oil from spent hydrodesulphurization catalyst

The deoiling process is a critical issue in catalyst regeneration and recovery of precious metals from spent catalysts. This study developed a fast and efficient method to recover crude oil from spent hydrodesulphurization (HDS) catalysts. We employed four solvents (p-xylene, acetone, dichloromethane, and n-hexane) with different polar and aromatic properties to remove crude oil from the spent catalyst. The effects of environmental factors, such as contact time, ratio of catalyst to solvent, temperature, stirring rate, and particle size on washing efficiency were investigated. The crude oil and solvent in the oil-containing washing solution were then effectively separated and recovered. The recovered solvent was used to evaluate solvent cycle washing performance, and the recovered oil was analyzed by gas chromatography-mass spectrometry. The spent and deoiled catalysts were characterized by scanning electron microscope, interracial rheometer, and contact angle. The results showed that p-xylene, which has similar polarity and aromaticity to the molecular structure of crude oil, achieved an excellent crude oil washing effect. The crude oil washing efficiency of the spent catalyst can exceed 94% in 2 min. Furthermore, the solvent was recycled 10 times, and still maintained a removal efficiency of over 93% for crude oil in the spent catalyst. Compared to crude oil, recovered oil has less viscosity, ash, residual carbon, and a higher heat of combustion, allowing it to be more easily refined and recovered, and to gain more energy as an energy source.

Synthesis and Characterization of New nano catalyst Mo-Ni /TiO2- γAl2O3 for Hydrodesulphurization of Iraqi Gas Oil

A new nano-sized NiMo/TiO2-γ-Al2O3 was prepared as a Hydrodesulphurization catalyst for Iraqi gas oil with sulfur content of 8980 ppm, supplied from Al-Dura Refinery. Sol-gel method was used to prepare TiO2- γ-Al2O3 nano catalyst support with 64% TiO2, 32% Al2O3, Ni-Mo/TiO-γ-Al2O3 catalyst was prepared under vacuum impregnation conditions to loading metals with percentage 3.8 wt.% and 14 wt.% for nickel and molybdenum respectively while the percentage for alumina, and titanium became 21.7, and 58.61 respectively. The synthesized TiO2- γ-Al2O3 nanocomposites and Ni-Mo /TiO2- γ-Al2O3 Nano catalyst were then characterized by XRD, AFM, and BET surface area, SEM, XRF, and FTIR. The performance of the synthesized catalyst for removing sulfur compounds was conducted through the pilot HDS laboratory unit, various temperatures range 275oC to 375°C, LHSV 1 h-1 were studied; moreover, the effect of LHSV 1 to 4 h-1 on the percentage of sulfur removal was also studied at the temperature of the best removal with constant pressure 35 bar and H2/HC ratio 200cm3/200cm3. The sulfur content results generally revealed that there was a substantial decrease at all operating conditions used, while the maximum sulfur removal was 87.75% in gas oil on Ni-Mo/TiO2-γ-Al2O3 catalyst at temperature 375˚C and LHSV 1h-1.

Effect of protective bed composition on deactivation of a hydrotreating catalyst

AbstractBACKGROUNDThe relationship between the chemical composition, texture, and the shape of the granules of the protective bed upstream hydrotreating, that influences the degree of metal removal from the residual vacuum gas oil, is a critical issue in oil refining.RESULTSThe character of the metal and sulphur distribution on the surface and in the volume of granules of the protective beds was studied for the model mixtures enriched with typical compounds deactivating hydrodesulphurization catalysts. The protective bed was operated along with the demetallization catalyst synthesized using local mineral raw materials (e.g., Angren high‐quality enriched kaolin) and production wastes (spent alumina sorbent from Shurtan gas chemical complex).CONCLUSIONIt is shown, the use of a two‐bed protective system most effectively extended the life‐time of the main hydrotreating catalyst. The spent and deactivated Al‐Co‐Mo catalyst can be efficiently used in the synthesis of the catalyst used for the pre‐cleaning upstream hydrotreating. © 2021 Society of Chemical Industry (SCI).

Study on surface reaction kinetics of SO2 temperature programmed on sulphur tail gas hydrogenation catalyst

This study is aimed to investigate the reaction energy of hydrodesulphurization catalyst for SO2 to H2S and the desorption energy of H2S. We used polymath software to fit the experiment data. The result of the fitting shows that the reaction energy is about 96 kJ/mol. In addition, a series of experiments with different heating rate was carried out to get the desorption energy of H2S on the catalyst. The obtained value is about 169.85 kJ/mol.

Efficient treatment of crude oil-contaminated hydrodesulphurization catalyst by using surfactant/solvent mixture

The purpose of this work is to investigate desorption efficiency for regenerating a crude oil-contaminated catalyst by using an ex-situ surfactant/solvent washing technique. We employed six types of surfactants and solvents for optimization, and established an optimal mixture of surfactant and solvent for the removal of crude oil from the contaminated catalyst. The efficiency of the surfactant/solvent mixture for the removal of crude oil from the contaminated catalyst was determined based on the mass ratio of surfactant to solvent, contact time, pH, and temperature. The raw catalyst, crude oil-contaminated catalyst, and after washing catalyst were characterized by interracial rheometer, zeta-potential analyzer, and scanning electron microscope. We found that the Brij-58/1,2-dimethylbenzene mixture could provide superior crude oil removal efficiency. At a higher mass ratio of 1,2-dimethylbenzene, the crude oil removal rate of the contaminated catalyst exceeds 95%. This result is attributed to the addition of the solvent to the surfactant solution. The solvent can significantly decrease the surfactant’s CMC and increase the micelle’s number, thereby enhancing the mixture’s washing efficiency. Since aromatic solvents and crude oil components have similar structures in terms of polarity and aromaticity, the Brij-58/1,2-dimethylbenzene mixed system has a strong affinity for crude oil components.

Recovery of molybdenum, cobalt and nickel from spent hydrodesulphurization catalyst through oxidizing roast followed by sodium persulfate leaching

The spent hydrodesulphurization (HDS) catalyst is an important secondary source for Ni, Mo, Co and Al metals. The high yield recovery of these metals is quite difficult due to the carbon accumulated on the catalyst surface and the stability of the metal oxides. Therefore, the leaching process in the presence of sodium persulfate (Na2S2O8) was carried out after the roasting pre-treatment to remove the carbon from the spent HDS catalyst structure and convert the metal oxides to the soluble form in this study. The optimum experimental conditions were determined as roasting temperature, 500 °C; roasting time, 120 min.; particle size, +75–30 μm; liquid/solid ratio, 12.5 mL/g; Na2S2O8 concentration, 0.4 M; leaching temperature, 50 °C; leaching time, 90 min and stirring speed, 400 r/min. Recovery of Mo (89.8%), Co (86.5%) and Ni (81.2%) from leach solution were achieved by precipitation method. The liquid film diffusion control mechanism best represents the proposed leaching process. On the other hand, the magnitude of Ea values (<20 kJ/mol) for Mo, Co, Ni and Al metals indicates that the leaching process is controlled by liquid film diffusion mechanism.

Exciting Opportunities for Solid-State 95Mo NMR Studies of MoS2 Nano-structures in Materials Research from Low to Ultra-high Magnetic Field (35.2 T).

Solid-state, natural-abundance 95Mo NMR experiments of four different MoS2 materials have been performed on a magnet B 0 = 19.6 T and on a new Series Connected Hybrid (SCH) magnet at 35.2 T. Employing two different 2H-MoS2 (2H phase) materials, a "pseudo-amorphous" MoS2 nano-material, and a MoS2 layer on the Al2O3 support of a hydrodesulphurization (HDS) catalyst have enabled introduction of solid-state 95Mo NMR as an important analytical tool in studies of MoS2 nano-materials. 95Mo spin-lattice relaxation time (T 1) studies of 160- and 4-layer 2H-MoS2 samples at 19.6 and 35.2 T show their relaxation rates (1/T 1) increase in proportion to B 0 2. This is in accord with chemical shift anisotropy (CSA) relaxation being the dominant T 1(95Mo) mechanism, with a large 95Mo CSA = 1025 ppm determined for all four MoS2 nano-materials. The dominant CSA mechanism suggests the MoS2 band-gap electrons are delocalized throughout the lattice-layer structures, thereby acting as a fast modulation source (ω oτc << 1) for 95Mo CSA in 2H-MoS2. A decrease in T 1(95Mo) is observed for an increase in B 0 field and for a decrease in the number of 2H-MoS2 layers. All four nano-materials exhibit identical 95Mo electric field gradient (EFG) parameters. The T 1 results account for the several failures to retrieve 95Mo spectral EFG and CSA parameters for multilayer 2H-MoS2 samples in the pioneering solid-state 95Mo NMR studies performed during the past two decades (1990-2010), because of the extremely long T 1(95Mo) = ~200-250 s observed at low B 0 (~9.4 T) used at that time. Much shorter T 1(95Mo) values are observed even at 19.6 T for the "pseudo-amorphous" and the HDS catalyst (MoS2-Al2O3 support) MoS2 nano-materials. These allowed useful solid-state 95Mo NMR spectra for these two samples to be obtained at 19.6 T in a few to < 24 h. Most importantly, this research led to observation of an impressive 95Mo MAS spectrum for an average of 1-4 thick MoS2-layers on a Al2O3 support, i.e., the first MAS NMR spectrum of a low natural-abundance, low-γ quadrupole-nucleus species layered on a catalyst support. While a huge gain in NMR sensitivity, factor ~ 60, is observed for the 95Mo MAS spectrum of the 160-layer sample at 35.2 T compared to 14.1 T, the MAS spectrum for the 4-layer sample is almost completely wiped out at 35.2 T. This unusual observation for the 4-layer sample (crumpled, rose-like and defective Mo-edge structures) is due to an increased distribution of the isotropic 95Mo shifts in the 95Mo MAS spectra at B 0 up to 35.2 T upon reduction of the number of sample layers.

Hierarchical Structure of NiMo Hydrodesulfurization Catalysts Determined by Ptychographic X-Ray Computed Tomography.

Hydrodesulphurization, the removal of sulphur from crude oils, is an essential catalytic process in the petroleum industry safeguarding the production of clean hydrocarbons. Sulphur removal is critical for the functionality of downstream processes and vital to the elimination of environmental pollutants. The effectiveness of such an endeavour is among other factors determined by the structural arrangement of the heterogeneous catalyst. Namely, the accessibility of the catalytically active molybdenum disulphide (MoS2 ) slabs located on the surfaces of a porous alumina carrier. Here, we examined a series of pristine sulfided Mo and NiMo hydrodesulphurization catalysts of increasing metal loading prepared on commercial alumina carriers using ptychographic X-ray computed nanotomography. Structural analysis revealed a build consisting of two interwoven support matrix elements differing in nanoporosity. With increasing metal loading, approaching that of industrial catalysts, these matrix elements exhibit a progressively dissimilar MoS2 surface coverage as well as MoS2 cluster formation at the matrix element boundaries. This is suggestive of metal deposition limitations and/ or catalyst activation and following prohibitive of optimal catalytic utilization. These results will allow for diffusivity calculations, a better rationale of current generation catalyst performance as well as a better distribution of the active phase in next-generation hydrodesulphurization catalysts.

Hierarchical Structure of NiMo Hydrodesulfurization Catalysts Determined by Ptychographic X‐Ray Computed Tomography

AbstractHydrodesulphurization, the removal of sulphur from crude oils, is an essential catalytic process in the petroleum industry safeguarding the production of clean hydrocarbons. Sulphur removal is critical for the functionality of downstream processes and vital to the elimination of environmental pollutants. The effectiveness of such an endeavour is among other factors determined by the structural arrangement of the heterogeneous catalyst. Namely, the accessibility of the catalytically active molybdenum disulphide (MoS2) slabs located on the surfaces of a porous alumina carrier. Here, we examined a series of pristine sulfided Mo and NiMo hydrodesulphurization catalysts of increasing metal loading prepared on commercial alumina carriers using ptychographic X‐ray computed nanotomography. Structural analysis revealed a build consisting of two interwoven support matrix elements differing in nanoporosity. With increasing metal loading, approaching that of industrial catalysts, these matrix elements exhibit a progressively dissimilar MoS2 surface coverage as well as MoS2 cluster formation at the matrix element boundaries. This is suggestive of metal deposition limitations and/ or catalyst activation and following prohibitive of optimal catalytic utilization. These results will allow for diffusivity calculations, a better rationale of current generation catalyst performance as well as a better distribution of the active phase in next‐generation hydrodesulphurization catalysts.

A Kinetic Model for Chelating Extraction of Metals from Spent Hydrodesulphurization Catalyst by Complexing Agent

In this present paper, chelating extraction of metals from spent hydrodesulphurization catalyst was carried out using ethylene diamine tetraacetic acid as complexing agent. Mo, Ni and Co metals were precipitated in ammonium molybdate, nickel dimethylglyoxime and cobalt hydroxide forms at pH:2, pH:6 and pH:10, respectively. The highest metal extraction yields (90.22% Mo, 96.71% Co, 95.31% Ni and 19.98% Al) were achieved under optimum process conditions. The activation energy values (Ea) of Co, Mo and Ni were calculated as 14.36 kJ/mol, 16.85 kJ/mol and 15.93 kJ/mol, respectively. It was determined that leaching kinetics fitted to the pseudo-first homogenous model and the chelating process was controlled by diffusion mechanism. In the light of the kinetic data, the kinetic equation including the process parameters was obtained as follows: $$\ln \left( {1 - x} \right) = 1.217 \times 10^{ - 4} [(C_{A} )^{1.068} \left( D \right)^{ - 0.929} (K/S)^{ - 0.850} (R)^{0.185} \exp ( - 6462.6/T)] t$$ . The results provided a new approach both for reducing the solid waste load of the petrochemical industry and for efficient recovery of metals from the spent hydrodesulphurization catalyst using EDTA.

The mechanism of additives to unsupported Ni-Mo hydrodesulphurization catalyst

A series of highly active unsupported Ni-Mo hydrodesulphurization catalyst prepared by coprecipitation method and characterized effect of additives Al2O3 on the structure performance by BET, and Py-IR tests. The results indicated the additives Al2O3 greatly increased the pore diameter and specific surface area and mechanical strength. And it increased the acid of L acid while formatted B acid sites. This paper also characterized the influence of phosphorus to the Ni-Mo catalyst. BET results show that phosphorus blocked the catalyst pore structure, specifically reduced the surface area of the Ni-Mo. But TPR, FT-IR studies have shown that phosphorus can form Al-P-O structure, weaken interaction between active phase and Al2O3, while the amount of tetrahedral Mo species was decreased and octahedral Mo species was increased.

Extraction of molybdenum, nickel and aluminium from spent Ni–Mo hydrodesulphurization (HDS) catalyst in oxalic acid solutions

ABSTRACTDissolution behaviour of metals in Ni–Mo hydrodesulphurization catalyst waste was investigated in a 1 L jacketed glass reactor. Samples were roasted at 500°C in a tube furnace for the removal of C and S prior to the dissolution experiments. It was determined that roasted samples consisted of mainly 27.692% Al, 20.238% Mo, 5.267% Ni and 4.331% P. Unmilled samples were used for dissolution experiments because dissolution experiments carried out with milled and unmilled samples showed that milling has no significant effect on the dissolution rate. Oxalic acid solutions with 0.25–1 M, reaction temperatures of 25–70°C and solid to liquid ratios of 10–100 g L−1 were used as experimental parameters. It was found that the dissolution behaviour of Ni is different from Al, Mo and P. 92% of Mo, 19% of Ni, 28% of Al and 72% of P were dissolved at optimum dissolution conditions.

Microbial leaching of heavy metals using Escherichia coli and evaluation of bioleaching mechanism

Bioleaching is recognized as a green process for the extraction of metals from various solid wastes. In the recovery of metals from spent catalyst using bioleaching with acidophilic bacteria, low Mo extraction is often reported. To address this problem, bioleaching of spent hydrodesulphurization catalyst with Escherichia coli and its mechanism was examined. Two-step bioleaching of ground catalyst (75–100 μm) at 0.5% w/v pulp density resulted in about 72% Mo and 68% Ni extraction in 30 days. The increase in pH of the media during bioleaching promoted the dissolution of Mo trioxide, i.e. Mo (VI). X-ray Photoelectron Spectroscopy also confirmed a higher concentration of Mo (IV) in the spent catalyst after bioleaching. Higher solubility under bioleaching conditions and complex formation with various metabolites led to increased Mo extraction. Thermal pre-treatment reduced resistance due to carbon deposits, and oxidized Mo (IV) to Mo (VI), leading to increased Mo bioleaching at 96%.