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Hydrogenation Process Used To Remove Compounds Biology Essay

Catalytic hydroprocessing is a hydrogenation process used to remove compounds containing nitrogen, sulfur, oxygen and/or metals from liquid petroleum fractions. These compounds adversely influence equipment and catalysts in the refinery. A reduction in the amount of metals in the oil is accomplished by the process of hydrodemetalation (HDM), where the molecules that contain metals lose these atoms by reactions of hydrogenation. The products of HDM reactions can accumulate in the catalyst pores, causing the formation of deposits which end up obstructing those pores irreversibly, blocking access to the catalyst sites and leading to a progressive loss of catalytic activity [1]. Therefore, hydroprocessing units are installed prior to units for processes such as catalytic reforming and catalytic cracking so that the expensive catalyst are not contaminated by untreated feedstock. One of the most practical and effective methods of feedstock demetalation (especially for vanadium and nickel) is the use of HDM catalysts. It has been shown that the most active HDM catalysts are those prepared from synthetic aluminium oxide or natural aluminium silicate enriched with the oxides of molybdenum, cobalt and nickel. The natural aluminosilicate activated with sulfuric acid was found to be best at removing vanadium and nickel [2]. Further, HDM catalysts with very small amounts of oxides of active metals belonging to sixth and seventh subgroups of the periodic table of the elements were found to be several times more effective than the usual hydrodesulfurization catalysts. In the hydrodemetalation(HDM) process, demetalation results from chemical transformations of the metal-bearing compound on the catalyst surface resulting in the deposition of the metals on the surface of the catalyst.

The use of model compounds in reaction kinetic studies has provided valuable insight into the fundamental processes occurring in resid HDM. The reaction of Ni and V porphyrins under commercial HDM conditions involves a sequential mechanism on two distinct types of catalytic sites. The porphyrins are initially hydrogenated, forming precursor species which subsequently undergo ring cleavage reactions, depositing the metal on the catalyst surface:

M-P ↔ M-PH2 → deposit + hydrocarbon

where P represents the starting porphyrin. Metal deposition occurs from the dehydrogenated metalloporphyrin intermediate (M-PH2). The resulting metal deposition ultimately deactivates the catalyst through fouling and pore blockage.

Investigation of nonporphyrin metallic compounds has not been very extensive, and their behavior during HDM are not known. It is expected that these compounds will behave roughly the same as porphyrin compounds. There are indications that the nonporphyrin metallic compounds may cause more severe problems than the porphyrins.

Heavy Iranian residue (b. 503-1036 oF; 9 wt. % C residue; 41 ppm Ni and 126 ppm V) was hydrogenated at 650 oF, 1500 psig, 2 h residence time, and 7000 rpm stirring rate in the presence of ZnCl2 (4.2 lb/bbl oil. The resulting products were an oil (b. ≥500 oF; yield 96.9 vol %; containing 11 ppm Ni and 20 ppm V) and a coke product (0.8 wt. %). Experiments showed that ZnCl2 and TiCl4 were superior to FeCl3 and AlCl3 as catalysts in demetallating the heavy residuum [3]. Results of demetalation are summarized in Table-4.1.

Baird and Bearden (1977) used sodamide to desulfurize and demetallize heavy hydrocarbons at elevated temperatures in the presence of H2. The salt produced after the reaction was separated from the desulfurized feedstock by filteration. Safaniya atmospheric resid was treated with 9.9% sodamide at 500 psig and 370 C resulting in 68% desulfurization and 77% demetalation. A detailed method for sodamide regeneration by electrolysis from the sodium sulfur salt was also presented. Additionally, recycling for reaction with additional feed was described. The methods include salt conversion to sodium polysulfide, nitrate, or chloride and electrolysis thereof [4]. Another improved process for residual oil treatment with molten sodium under H2 pressure between 100-200 atm and above 400 C was studied by Bearden (1978). Sodium treatment of Safaniya resid reduced sulfur to 0.2% and Ni+V to less than 1ppm compared to 3.91wt% and 97 ppm in the feed, respectively [5]. Demetalation results of both patents are gathered in Table-4.1.

Catalytic method reported by Wieckowska et al. (1988) for the demetalation of petroleum, petroleum products, and petroleum refining residues comprised contacting the feed with a SiO2 and/or Al2O3, or silica gel-adsorbent (pore size 100-1000 .ANG.) activated with a mineral acid (esp. H2SO4) followed by contacting the feed with an Fe catalyst at 520-670 K with simultaneous introduction of H at a flow rate equal to that of the feed. Absorbent-catalyst was prepared by treating silica gel 100 g with H2SO4 30 g, drying of the activated silica gel, and combining 1/3 of the activated adsorbent with 2/3 volume parts of a catalyst containing Fe2O3. The activated adsorbent and catalyst were placed in a reactor followed by feeding heavy petroleum distillate 100 kg containing V, Ni, and Fe 80 ppm. Hydrogen 300 m3 was fed to the reactor and the temperature was kept at 670 K. The contact time was 1.8 x 103 s. The product contains V, Ni, and Fe 8 ppm [6] .

Bowes et al. (1986) of Mobil oil described a method to demetallize and desulfurize residual oils by adding to the oil an aromatic solvent and contacting the mixture in the presence of hydrogen with an alumina having an average pore size greater than about 220 Angstroms. Two samples of Arabian Heavy and Light resids were mixed with ortho-xylene in ratios of 1:8 and 1:4. The samples were demetallized and desulfurized by pressurizing them in an autoclave for one hour at 350 C and 68 atm [7].

Aldridge et al. (1991) of Exxon achieved the removal of metallic contaminants from heavy hydrocarbons using vanadium oxide supported on activated carbon. A schematic of the process and the effects of process variables were provided in this patent. Several examples were carried out to remove vanadium and nickel from heavy hydrocarbons such as a 20-30% cut of Arabian Heavy vacuum resid at 52 atm and 290C. The reaction was highly selective with minimal occurrence of other reactions. Hydrogen consumption was only 50 to 150 scf/bbl. The results showed that the activity of vanadium removal can be increased by increasing the percentage of vanadium on the activated carbon support [8].

Rankel (1994) of Mobil oil used activated carbon catalysts to treat heavy oils in the presence of hydrogen. The main objective was to reduce the content of nickel and vanadium in the feedstock and achieve conversion of the carbon residue for producing a lighter oil. An atmospheric resid containing 4.2wt% sulfur, 104 ppm vanadium, and 32 ppm nickel was treated in a trickle bed micro unit reactor. The trickle bed was charged with different types of commercially activated carbon catalysts and operated at 400C [9].

A process for the hydrotreating of heavy hydrocarbons in supercritical fluids was demonstrated by Piskorz et al. (1996) of Natural Resources Canada. This single-step process uses supercritical fluids and activated carbon as a catalyst. Examples cited include the treatment of Athabasca bitumen (sulfur content 5.44wt%, Ni+V 300ppm) with n-dodecane as a solvent in a hydrogen atmosphere. Sulfur content was reduced to 1.16% with complete demetalation. Three runs were performed at different pressures, all with a 1:1 by mass mixture of bitumen and n-dodecane as feed; the hydrogen feed ratio was 1,220 m3 hydrogen (STP) per m3 of liquid feed. The same weight of catalyst was used in all tests [10].

Heavy oil is hydrodesulfurized and demetallized by treatment in a first stage with hydrogen in the presence of a catalyst with fine pores, and in a second stage in the presence of a catalyst with larger pores and a specified pore size distribution. Thus, second stage treatment of heavy oil containing 53.4 ppm V over a catalyst containing CoO 4.5, MoO3 16.0, and Al2O3 79.5% with pore vol. 0.525 mL/g and average pore radius 84.ANG removed approximate 60% V, compared with approximate 40% for a catalyst with pore volume 0.47 mL/g and average pore radius 35.ANG [11].

Mobil Oil Corp., USA developed a catalyst for demetallizing and desulfurizing hydrocarbons. The catalyst contained 1-10 wt. % of an Fe-group metal (Co or Ni) and 5-25 wt% of a Group VIB metal as the oxides or sulfides on a calcined (704-927F°) support containing 85% Al2O3 (boehmite) and 0.5-7.0 wt.% of a rare earth. At least 60% of the pore volume of the catalyst was comprised of 80-200-Å pores. The demetallized hydrocarbons then underwent catalytic cracking, hydrocracking, or coking. Thus, a catalyst contained 3.5 wt.% CoO, 10 wt.% MoO3, and 1.5, 3, or 6 wt.% rare earth. A Lago atmospheric residuum containing 235 ppm V and 2.12 wt.% S was treated over the catalyst after it had been calcined at various temps. (538-871F°). V removal was 56.6-71.1 wt.% and S removal 48.7-55.9 wt.% [12].

Residfining, an Exxon catalytic desulfurization-demetalation process for heavy petroleum fractions, was extended by a series of catalyst improvements and engineering to include hydroconversion of distillation residues (b. > 1050°F) [13].

The heavy petroleum oils, containing heavy metals (e.g., Ni) and S compounds, were catalytically hydrodesulfurized (300-450°C, 50-250 kg/cm2, 0.1-4.0 h-1 liquid space velocity, 200-1500:1 H-oil vol. ratio) and then demetallized in a magnetic field. Thus, a vacuum distillation residue was hydrodesulfurized (400°C, 150 kg/cm2, 0.5 h-1 liquid space velocity, 1000:1 H-oil vol. ratio) in a fluidized bed of zeolite catalyst and then demetallized in a magnetic field. About 80% of the S compounds and 45% of the Ni were removed [14].

Heavy and sour petroleum fractions were hydrodemetallized in a bed of sulfurized Al2O3 catalyst. Thus, a catalyst was prepared by passing (CH3)2S2 (250°C, 1 h-1 space velocity) through a bed of Al2O3 granules (surface area 188 m2/g, pore vol. 0.77 cm3/g). The catalyst was then used to hydrodemetallize a refining residue (d. 1.025, Conradson carbon 18%, S 5%, V 120 ppm, Ni 55 ppm). At 410°C the removal of S, V, and Ni reached 15, 85, and 68%, respectively [15]. Results are summarized in Table-4.1.

Hydrodemetalation of vanadium and nickel porphyrin model compounds over sulfided cobalt-molybdenum/alumina catalyst was performed by Chen and Massoth (1988) in a batch stirred autoclave at several temperatures, hydrogen (H) pressure and initial porphyrin concentration. A hydrogenated intermediate leading to deposited metal was found for both reactants. The time course of the reaction followed pseudo first order in reactant concentrations at >350o, but followed lower order at lower temperatures. Runs at different initial concentrations showed that reaction inhibited by adsorption of reactant and products. HDM rates increased with temperature and H pressure and were very low without catalyst or H present. An apparent activation energy of 24 kcal/mol for the overall disappearance was obtained for both reactants. Kinetic analysis of HDM of Ni porphyrin (NiP) showed, in addition to a pathway through the hydrogenated intermediate, an apparent direct pathway to hydrocarbon products. The latter was interpreted in terms of a direct conversion of adsorbed NiP to products in a single adsorption step, without desorption of hydrogenated intermediate. Evidence was obtained for a change in mechanism at >350oC [16].

Crude oils that could not be easily or economically transported or processed using conventional facilities, with microcarbon residue content (ASTM D 4530) > 0.1 wt.%, total acid no. (TAN)>0.1, and with >10 wt.% material boiling in the vacuum gas oil range (ASTM D5307), were hydrotreated and hydrodemetalated in the presence of a supported Group VIB metal catalyst, esp. Mo and W on Al2O3, with median pore diameter> 180 Å. Additional elements of the catalysts were derived from Groups VIB, Group VIII and Group VA elements. The crude oil product had a microcarbon residue content of <90% of the initial microcarbon residue content, <10% of the initial TAN, and 70-130% of the initial vacuum gas oil content [17].

A cracking unit for cracking of petroleum refining residues included a riser reactor and a stripper/separator with adjustable outlets in flow communication with separate regeneration units for regeneration of cracking catalysts and adsorbents. The adsorbents, which were used for removal of Conradson carbon precursors, high-molecular weight nitrogen compounds, and impurity metals (esp. Ni and V) in the residues were injected into the riser reactor such that they came into contact with fresh residue feedstock prior to coming into contact with fresh and/or regenerated cracking catalyst. Suitable adsorbents were selected from microspheres derived from calcined clay, calcined and crushed coke, magnesium oxide, silica-alumina, and residue cracking additive for removal of Conradson carbon precursors and metals [18].

The kinetics of hydrodemtallization (HDM) of vanadyl etioporphyrin (VO-EP) was studied in a batch autoclave at 543 K and 5 MPa of total pressure, with white oil as solvent and presulfiding CoMo/Al2O3 (TK 710) as catalyst. The most widely accepted kinetc model comprided of only dehydrogenated intermediate (VOEPH2) did not fit the experimental data. A new model with two reversible hydrogenation steps and a lumped irreversible hydrogenolysis step was proposed, and followed the concentration trace of reactants (VO-EP and VO-EPH2) very well for most reaction times [19].

The influence of the hydrodynamic effects on the plug flow model deviation in the hydrodesulfuration (HDS) and hydrodemetalation (HDM) reactions of a petroleum residue was evaluated by Callejas and Martinez [20]. The removal of sulfur, vanadium, and nickel from a heavy residual oil was examined, using a commercial catalyst. The possibility of incorporation chemical and hydrodynamic complexity in the kinetics analysis of hydrotreating reactions in a pilot trickle bed reactor were discussed. The study was done in a small pilot scale trickle bed reactor in continuous operation at 375 C and 10MPa of partial hydrogen pressure with a commercial NiMo/alumina catalyst. The nickel removal reaction, a first order liquid-limited reaction, was used to test the predictions of several, models, which incorporated the influence of the hydrodynamics on the catalyst utilization. For this task, additional experiments in a stirred tank reactor at the same conditions were done in order to determine the value of the effectiveness factor for denickelation reactions. Comparison of model predictions and experimental data indicated that the use of a hydrodynamic parameter in the models improved the data fit.

A combined hydrotreating (HDT)-fluid catalytic cracking (FCC) process was used to increase light products yields. In the case of topping reforming, 190 vol. % light Arabian crude oil was necessary to give 100 vol. % gasoline and middle distillates, while only 104 vol. % was necessary in the HDT/FCC process. The Mobil catalyst system could be used with atm. and vacuum residuums containing 100 ppm metal, whereby the metal content was reduced to 2 ppm and the S to 0.5%. Process conditions were 145 kg/cm2 and 370-440 degree. The H consumption was 80 m3/ton feed. The C5+ yield was 102-3 vol. % of the feed. Catalyst life was 6-12 month [21].

Petroleum distillation residues were treated with H over a cracking catalyst and solid asphalt was removed from the product, to give a cracking feedstock low in metals content and Conradson C no. The process also yields gasoline and middle distillates. Thus, such treatment of an atmospheric distillation Residue (Conradson C 9.4 wt.%, 123 ppm V, 43 ppm Ni) over a sulfided equilibrated Filtrol 900 fluid-catalytic-cracking catalyst with H at 800°F reduced the Conradson C content by 60-99%, V by 96-9%, and Ni by 83-98%. Removal of 3.4% solids from the total effluent (3 ppm V, 4 ppm Ni) and removal of asphaltenes from the liquid product with isopentane gave oils and resins containing 1 ppm V and 2 ppm Ni. [22]. Results of the experiments are also summarized in Table-4.1.

Hydrodesulfurization-demetalation by the Gulf process is extended to include both sour light (Kuwait) and sour heavy (Lloydminster) crude petroleum. Process economics and refinery schemes are given for the Kuwait (containing. 2.9 wt.% S and 35 ppm Ni-V) and Lloydminster (containing. 3.6 wt.% S and 200 ppm Ni-V) crudes, including refining of hydrodesulfurized fractions for gasoline, propane LPG, and fuel oil production [23].

The results of a cooperative project between the U.S. and the USSR to exchange technology on the demetalation step of an overall process to produce low-S fuel oil from heavy petroleum residues are discussed. Catalysts and petroleum residua feedstocks were exchanged and tests were carried out by each nation. Each nation described its own test equipment and operating procedures. Included for each aging test are graphs showing the degree of demetalation and desulfurization and the rate of catalyst deactivation. Fresh and used catalyst analyses are presented, along with detailed run summaries and product inspections. The Mo-impregnated catalysts had about equal demetalation capabilities; however, the U.S. catalyst had higher desulfurization capability during demetalation. [24].

A Co-Mo/Al2O3 demetalation-desulfurization catalyst for petroleum atmosphere and vacuum residues has 40-75% of its pore volume in 150-200 Å diameter pores and up to 5% of its pore volume in >500 Å diameter pores. The support is prepared from a q- or d- Al2O3, obtained by calcination of an a monohydrate or b trihydrate to 1700-2000°F. Thus, hydrotreating of a vacuum residual oil, containing 4 wt.% S and 85 ppm metals (Ni-V), a Co-Mo/ Al2O3 produced less coke and residue b. >1000°F, and had increased H consumption after 5 days on stream, compared with a comercial Co-Mo catalyst. [25].

Rosa Brussin removed metals and S from crude oil by clay catalysts (SiO2 53.98, Al2O3 16.96, and Fe2O3 7.16%) containing V or Ni. Demetalation was promoted by the presence of vanadium or nickel because of an electrical interaction. Vanadium contents ranged from 0.11 to 1.60% and Ni from 0.07 to 0.95%, and the combinations were Ni 0.1, V 0.5 and Ni 0.3, V 1.5%[26].

A hydroconversion process for heavy crude petroleums and topped crudes comprises mixing the feedstock with a thermally decomposable metal catalyst (e.g., Mo naphthenates or phosphomolybdic acid) and HCl (anhydrous or as 38% aquas solution) or a thermally decomposable HCl precursor [tert-amyl chloride [594-36-5]]. Thus, Ni and V removal and Conradson C conversion were higher in the hydroconversion of a Cold Lake crude petroleum with Mo naphthenate and tert-amyl chloride than hydroconversion in the absence of tert-amyl chloride. Similarly, coal hydroliquefaction in 1-methylnaphthalene [90-12-0] in the presence of phosphomolybdic acid and tert-amyl chloride resulted in less PhMe-insoluble material than hydroconversion in the absence of tert-amyl chloride. [27].

A catalyst for the hydrogenation of a topped crude oil comprises NiO 1.1, CaO 0.9, and MoO3 10.5 wt.% supported on Al2O3 with sp. Surface area 170 m2/g. The catalyst was prepared by impregnating Al2O3 (sp. surface area 177 m2/g) with 360 mL of NH4OH solution containing 60.0 g (NH4)6Mo7O24, 20 g Co(NO3)2, and 24.7 g Ni(NO3), drying the catalyst precursor at 110° for 1 h, and calcining it at 550° for 1 h. A Kuwait topped crude (containing 4.3 wt.% S) was thus hydrodesulfurized at 380°, 150 kg H/cm2, and liquid space velocity 1 h-1, resulting in 80.9% S removal and 79.1% demetalation [28].

Initial studies performed to provide a basis for studying mechanisms associated with the co-processing of coal and residual oil are described. The areas investigated included the response of coal and petroleum residue combinations to processing under thermal hydrotreatment conditions, the means of increasing the conversion of coal, and the nature of residue demetalation effects. Maya atmospheric bottoms were superior to Boscan atmospheric bottoms or North Slope vacuum bottoms for the conversion of Illinois No. 6 coal to liquid or solvent products. The extensive demetalation of the liquid product was a function of the amount of coal added. Results obtained by using different coal and residue combinations under thermal conditions and in the presence of various additives suggest that an adsorptive mechanism is operative. The primary interactions leading to demetalation are between the metal complexes of the residue and the insoluble carbonaceous coal-derived material. Demetalation of the liquid product was not dependent on conversion of the organically complexed metal in the residues to inorganic form [29].

A sample of bauxite containing 28% Fe2O3 was activated by hydrothermal treating and Mo impregnation, and tested as a catalyst in the hydrotreatment of a heavy petroleum residue in a bench-scale trickle-bed reactor. The thermally treated bauxite exhibited a significant demetalation activity, attributable to iron sulfide. After addition of 4.7% MoO3 to the activated bauxite, hydrodesulfurization was strongly promoted. At highest conversion, H consumption was <100 hm3/m3 of oil. NMR analysis of the products showed a limited saturation of aromatic rings, hydrocracking, significant in the presence of activated bauxite, was somewhat reduced by Mo addition [30].

Metals contained in a hydrocarbon containing feed stream were removed by contacting the hydrocarbon containing feed stream under suitable demetalation conditions with hydrogen and a catalyst composition comprising zirconium phosphate, cobalt phosphate and a metal phosphate where the metal is selected from the group consisting of nickel and vanadium. Kimble found that the life and activity of the catalyst composition may be increased by introducing a decomposable metal compound selected from the group consisting of the metals of Group V-B, Group VI-B, Group VII-B and Group VIII of the Periodic Table into the hydrocarbon containing feed stream prior to contacting the hydrocarbon containing feed stream with the catalyst composition. A mixture of 74:26 (wt.%) Venezuelan Monagas pipeline oil and PhMe, having a gravity 17-18° API and containing 42.9-68.0 ppm Ni and 281-315 ppm V was demetalized (at 425° and 100 psig H, liquid space velocity 1.52-1.59 h-1) in a reactor packed with any of the catalysts. The removal of the metals was 74-91%. Addition of 70 ppm Mo(CO)6 to feedstocks improved the demetalation [31].

The use of 2-bed catalytic systems for the removal of heavy metals and S from heavy petroleum residues is discussed. The 1st bed contains a hydrodemetalation catalyst which protects the 2nd hydrodesulfurization-catalyst bed from poisoning by the metals, decreases pressure changes in the 2nd bed, and "precracks" heavy ends, thus facilitating the operation and improving the life of the hydrodesulfurization catalyst [32].

Gonzalez performed demetalation of heavy crude oil by a series of catalysts. The catalytic activity was tested in a continuous flow system with a fixed-bed reactor, at 450 ºC and hydrogen pressure 20 kg/cm2/liter. The evolution of Fe in clay catalysts employed in hydrodemetalation (HDM) of heavy oils has been studied by the Moessbauer effect. He found Pyrrhotites as first of the active phases in HDM, which appear during the process [33].

Twelve Mo-, Mo-S-, Mo-P-, Mo-P-S-, Mo-Co-, Mo-Co-S-, Mo-Co-P-, and Mo-Co-P-S- containing catalysts were prepared from single or multiple starting materials by mixing. These catalysts were tested in high-pressure thermal hydrocracking of Venezuelan Morichal petroleum crude (containing S 4.19, N 0.67, and asphaltenes 17.5 wt.% and 463 ppm V and 100 ppm Ni) in an autoclave at 420 or 470° and 100 kg/cm2 initial H; the reactions were carried out especially with respect to addition of supplemental P or S, desulfurization, and demetalation. Starting materials include Mo dithiophosphate (I), Mo dithiocarbamate, Mo acetylacetonate, Mo naphthenates, Co acetylacetonate, Co octylate, dioctyl phosphate, dioctyl dithiophosphate, and S. Mo dithiophosphate was highly active for removal of S and V; its activity was enhanced by addition of Co compounds. The addition of P compounds was essential for V removal; the presence of P and S was effective for both removal of S and V. Reuse of Mo-Co-P-S catalysts, which can be recovered from solid reaction residues, results in a gradual decline of activity to a saturation level, which is still higher than the initial activity of conventional Co-Mo/Al2O3 catalysts [34].

Hydrotreating of Iraqi vacuum residues was carried out on Ni-Mo/Al2O3 at 300-400°, 0.7-2.94 h-1 liquid-space velocity, 6 MPa, and 300:1 (vol.) H:oil ratio. Desulfurization and Ni and V removal obeyed fundamental 2nd order kinetics. Kinetic data for S removal are: 85.12 kJ/mol (activation energy), 81.10 kJ/mol (DH), and -135.5 kJ/mol-K (DS); similar data for Ni removal are 36.5 kJ/mol, 31.4 kJ/mol, and -231.4 kJ/mol-K, respectively; similar data for V removal are 81.8 kJ/mol, 76.6 kJ/mol, and -162.4 kJ/mol-K, respectively [35].

The hydrodemetalation of a heavy vacuum fraction from petroleum was studied in a fixed bed-reactor. Natural aluminosilicates and sulfides of Mo, Co, Ni, / γ- Al2O3 are used as catalysts. The natural aluminosilicate activated by sulfuric acid appear to be best at removing vanadium and nickel [36].

Slurry hydroprocessing of the petroleum vacuum residue with bifunctional catalysts [i.e., transition metals (hydrogenative activity) on supports with cracking activity] was studied. Both sulfided and unsulfided Ni-W were evaluated on Al2O3, silica-alumina, USY (zeolite), montmorillonite, sepiolite, and activated carbon at 800°F and 2000 psig. The results were compared with those obtained for dispersed oil-solution NiW compounds. Compared with sulfided NiW/Al2O3, use of sulfided NiW supported on zeolites, clay, activated carbon, or silica-alumina produced slightly more conversion of fraction b. ³1000°C (corresponding to 5-10% more distillate at the same reaction times) at the expense of 3-5% coke formation. This would correspond to a reduction of metals content to <100 ppm in the product (from 262 ppm in the feed) [37].

Batch hydrogenation of various kinds of petroleum heavy oil and coal is carried out in autoclaves of small capacity. The light fractions of the processed oil increase during the cohydrogenation process. The saturated hydrocarbon content and molecular wt. of the processed oils decrease, while the aromatic content increases with increase in hydrogenation temperature. Contents of Fe, Ni, Cu and S in the processed heavy oils are generally reduced, especially in the case of Daqing heavy oil. The removal ratio of the processes oil is higher than 90% in some cases [38].

The catalysts are porous SiO2, which are free of Group VI metals, contain <1% other metal oxides, and have average pore diameter 150-1000Å. V and Ni containing heavy oils are treated with H in the presence of the above catalysts. Improvement of petroleum plasticizer for rubber compounds by selective demetalation over a manganese catalyst [39].

Process for the demetalation of petroleum crude oils comprises contacting the oil with hydrogen with a catalyst having at least one metal or compound thereof of Group VIII and/or Group VIB metals as its active material supported on a carrier comprising a zeolite with a SiO2/Al2O3 ratio of >5 and a unit cell size of 24.30-24.60 [40].

Catalysts prepared by Manganese nodules, obtained from the bottom of Sturgeon Bay in lake Michigan were used to demetalate crude oil. Properties of catalysts (named catalyst E and F) and demetalation results are summarized in Tables 4.2, 4.4 and 4.5. Among other catalyst in Table 4.5, catalyst F is found to be best metal removal and removed 92.4% vanadium and 80.4% nickel [41].

Table 4.1

Catalytic Hydrodemetalation Methods

Reference:

US Patent 4148717

US Patent 4007109

US Patent 4076613 [41]

French Patent 2542754

US Patent 4082648

Sample

Heavy Iranian Residue

PDR

PDR

PDR

PDR

Catalyst

ZnCl2 4.2lb/bbl oil

Sodamide NaNH2 9.9%

Molten Sodium

Al2O3 granules (Activated by (CH3)2S2

Fluid-catalytic-cracking catalyst (Filtrol 900)

Temperature

650 F

370 C

400 C

410 C

800 F

Time

2h

*

*

*

*

Pressure of hydrogen

1500psig

500psig

100-200 atm

*

*

% Removal Vanadium

84.1

77 **

99 **

85

96-99

% Removal Nickel

73.2

68

83-98

Other

ZnCl2 and TiCl4 were superior to FeCl3 and AlCl3

68% Desulfurization

94.5% Desulfurization

Desulfurization 15%

Solvent Extraction with Isopentane used to obtain oil from reaction mixture.

* Values not given

** Total demetalation

Table 4.2

Composition of Hydrodematalation Catalysts [36 & 43]

Catalyst

Preparation/Composition of catalysts

A

Natural aluminosilicate, a basalt detrital mineral of halloysite structure containing strongly magnetic iron compounds. Composition: SiO2 32 wt%, Al2O3 23 wt%, Fe2O3 19 wt%, TiO2 2.1 wt%, H2O 11 wt%.

B

Activate Catalyst A with 50% H2SO4 and Ammonia solution.

C

15% MoO3, 4.5 wt% CoO deposited on -alumina.

D

20% MoO3, 8 wt% CoO, wt.2% NiO, deposited on -alumina

E

This catalyst was prepared by Manganese nodules, obtained from the bottom of Sturgeon Bay in lake Michigan. These nodules, after recovery from the lake bottom, were washed to remove salt, water and mud. They were then crushed, leached with boiling water five times, dried to constant weight at 100 C and sieved to 14-30 mesh (U.S. standard sieve series).

F

Catalyst E was sulfided by passing through the reactor 100% H2S at 320 F at 1 atmosphere pressure, and at a space velocity of 480 volumes of H2S per volume of nodules for a period of 8 hours.

Table 4.3

Physical Properties of Catalyst

Pore Diameter (Å)

A

B

C

D

3-6

21

70.2

110.8

89.6

6-10

14.2

52.6

57.2

19.1

10-20

21.6

30.8

15.2

7.1

20-60

9.5

6.6

4.1

2.3

60-67

0.1

0.2

0.4

0.3

67-200

0.3

0.3

0.6

0.4

3-200

66.7

160.7

188.3

118.8

Mean Pore Diameter (Å)

106

86

70

68

Table 4.4

Physical Properties of Catalyst E and F

US patent 3716479

Surface area, (m2g-1)

200

Particle density (g cm3)

1.49

Pore diameter Angstroms unit (Å)

81

Pore volume (cm3 g)

0.409

Real density g cm-3

3.75

Manganese (Mn), wt.%

35.4

Iron (Fe), wt.%

<0.01

Cobaltous oxide (CoO), wt, %

0.04

Molybdenum trioxide (MoO3), wt.%

0.08

Table 4.5

Hydrodemetalation Results of Catalysts: A, B, C, D, E, F

Catalyst A

Catalyst B

Catalyst C

Catalyst D

Catalyst E

Catalyst F

Removal of Vanadium %

50.8

88.3

66.4

59.4

82.3

92.4

Removal of Nickel %

37.5

77.5

50.0

42.5

58.6

80.4

Removal of Sulfur %

23.4

27.2

77.0

61.7

22.7

35.4

Removal of Nitrogen %

6.0

8.0

32.0

20.0

5.0

10.0

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