HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal-derived slurry oil at 90 bar initial pressure for temperatures of 380-460^° C and residence time of 15-60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂-pressure of 60-150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂-pressure of 90-150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂-pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

DIRECT HYDROGENATION OF A SPANISH LOW RANK COAL. THE EFFECT OF PROCESS VARIABLES

ABSTRACT

The effect of operating conditions on the liquefaction behaviour of a Spanish lignite was studied using a 250 ml stirred autoclave, and the following operating conditions (except otherwise specified): 400 °C, 1 hour, 3.5 MPa initial (cold) H₂ pressure, 400 rpm and 40 g/10 g tetralin/coal charge. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents

The influence of temperature was explored in the 300–475 °C range, observing little further improvement in liquefaction yields over 400 °C, and retrogressive reactions over 450 °C. The effect of time was studied from 0 to 180 minutes and was concluded that 1 hour is an appropriate period for liquefying a black lignite, since there is little further conversion for longer times. The influence of pressure and gas type was studied using 0, 3.5 and 7.0 MPa initial (cold) pressure of H₂ and of N₂, and the effect of stirring using 0 and 400 rpm. Little influence of these variables was observed, which is attributed to the strong H-donor solvent, high solvent/coal ratio and long reaction time used.     

THERMAL CRACKING (VISBREAKING) STUDIES ON QUYARAH RESIDUES

ABSTRACT

Visbreaking experiments on Quyarah long residue have been conducted in a continuous laboratory-scale visbreaking unit at different temperatures from 435^°C to 490^°C at one pressure (7 bar) and constant residence time (90 sec.). Data on yield of different products have been reported. Further, thermal cracking experiments on visbroken vacuum gas oil under relatively high severity were also given in the same unit in order to reduce the residual yield of Quyarah crude.     

MILD HYDROCRACKING OF VACUUM GAS OILS TO IMPROVE FCC PERFORMANCE AND MAXIMIZE DISTILLATE YIELDS

ABSTRACT

A pilot plant study was conducted on mild hydrocracking of heavy vacuum gas oils derived from two different crude sources over a commercially available catalyst to determine the possibility of utilizing mild hydrocracker bottoms as fluidized catalytic cracking feedstock along with improved middle distillate yields. The mild hydrocracking experiments were conducted at 390°C, 60 kg/cm², 1.0/h liquid hourly space velocity and H₂/oil ratio of 390 l/l in a pilot plant trickle bed reactor using two catalyst beds for pretreatment and mild hydrocracking reactions. The experimental results showed that mild hydrocracking would result in valuable middle distillates with low sulphur and nitrogen content. With research octane number of 78, the naphtha obtained from mild hydrocracking was found to be a good blending stock for gasoline pool. The middle distillate fraction (140–370°C) obtained from mild hydrocracking product was found to have cetane number in the range of 48–54. The bottom product from mild hydrocracking of heavy vacuum gas oils was found to be a good feedstock for fluidized catalytic cracking unit because of its low sulphur, nitrogen and aromatic contents. The data obtained from pilot plant studies showed that the processing of mild cracker bottom in FCC unit would result in better quality fuels.     

Effect of catalyst deactivation on vacuum residue hydrocracking

Accelerated deactivation tests of the pre-sulfided Mo–W/SiO₂–Al₂O₃ commercial catalyst were performed using heavy vacuum petroleum feedstock. High reaction temperature employed in the accelerated catalyst aging resulted in large amounts of carbonaceous deposition with high aromaticity, which was found to be the principal deactivation cause. The effect of catalyst deactivation on hydrocracking of vacuum residue was studied. Experiments were carried out in a batch reactor at 60 bar, feed to catalyst ratio 10:1 and temperature 425 °C. The duration time for a cycle-run was 4 h. On increasing the interval duration times from 4 to 20 h (i.e. five cycles), the quality of the hydrocracked products was decreased. In each cycle-run, a fresh feedstock was used with the same sulfide catalyst. The quality of distillate products, such as hydrodesulfurization (HDS) was decreased from 61.50% to 39.52%, while asphaltene contents of the total liquid product were increased from 2.7% to 5.2% and their boiling ranges were increased during these duration times due to the successive catalyst deactivation during the 5 cycle-runs, caused by successive adsorption of coke formation.     

Thermal Hydrocracking Kinetics of Chinese Gudao Vacuum Residue

Abstract

The thermal hydrocracking kinetics of Chinese Gudao vacuum residue was studied in a batch autoclave reactor. The temperature ranged in 390–435°C and the initial hydrogen pressure was 7.0 MPa at 20°C. Ammonium phosphomolybdate (APM) in its dispersed phase was the catalyst. The reaction products, gas, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and coke, were separated during and after experiments, and their yields vs. reaction time were obtained, for four reaction temperatures: 390, 405, 420, and 435°C. The activation energy was calculated from a traditional kinetic model to be 218.6 kJ/mol. A new kinetic model was proposed in this work that allows for the calculation of activation energy with a minimum number of three tests, each at a different temperature. This is comparable to the traditional model which requires a minimum of 12 tests; a minimum of four tests for one temperature and a minimum of three temperatures. The activation energy calculated from the new model with four tests is 229.6 kJ/mol, only 5% greater than that obtained from the traditional model. The reaction rate constants obtained from this model are also consistent with those from the traditional model.     

Synthesis and characterization of Ni-Mo catalyst using pea pod (Pisum sativum L) as carbon support and its hydrotreating potential for gas oil,Jatropha oil,and their blends

Ni-Mo catalyst was prepared directly on pea pod using boric acid as a surface modifying agent. The BET surface area of the pea pod derived carbon based catalyst was found to be 380 m²/g. The activity of the inventive catalyst was tested in micro down flow reactor for hydrotreating of gas oil, 20% Jatropha oil in gas oil at the temperature range of 330–370°C, 90 bar H₂ pressure and space velocity of 1 h^?1 followed by Jatropha oil at 370°C, and keeping the other process parameters constant. The gas oil hydrotreating activity of the catalyst studied at temperatures below 370°C was found to be lower than that of the commercial alumina- and carbon-supported Ni-Mo catalysts; however, the activity was found to be comparable at 370°C.     

Hydrogenation of aromatic hydrocarbons over nickel–tungsten sulfide catalysts containing mesoporous aluminosilicates of different nature

The hydrogenation of naphthalene, toluene, and 2-methylnaphthalene used as model compounds; the hydrodearomatization of the methylnaphthalene fraction; and the hydrocracking of oil sludge over Ni–W sulfide catalysts supported on BEA/TUD, BEA/SBA-15, and ZSM-5/SBA-15 composites containing SBA-15 and TUD mesoporous silicates have been studied. Catalytic tests have been conducted in an autoclave at 300–400°C and an initial hydrogen pressure of 50–90 atm. It has been found that the highest activity is exhibited by the catalyst based on the ZSM-5/SBA-15 (1) composite prepared by the double-templating synthesis and characterized by a specific surface area of 400 m²/g and an acidity of 409 μmol/g. Thus, in the case of dearomatization of the methylnaphthalene fraction at 300°C and an H₂ pressure of 50 atm, the content of diaromatic compounds has decreased from 99.0 to 53.4%, while the amount of sulfur compounds has decreased almost 15-fold. The hydrocracking of oil sludge over NiW/ZSM-5/SBA-15 (2) at 400°C and an H₂ pressure of 90 atm has led to an increase in the content of light fractions to 52%.     

LIQUEFACTION AND THE CHARACTERIZATION OF COAL DERIVED LIQUIDS OF MENGEN LIGNITE

ABSTRACT

The liquefaction characteristics of Mengen lignite has been investigated in the presence of cobalt-molybdenum on alumina catalyst in a 1 lt batch autoclave system with anthracene oil used as solvent. The experiments were carried out in the range of 15–60 atm for initial hydrogen pressure, 360–440°C for reaction temperature, 1–5 for solvent to coal ratio and 0–20% of coal for catalyst loading which were chosen as process variables. Coal particle size and reaction time were kept constant as below 200 mesh and 30 minutes respectively, (Erdem 1987)

The product was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltenes and oils. The oil fraction was further separated by column chromatography while the asphaltenes were separated into basic and acid/neutral fractions. The preasphaltenes were divided into two fractions as carbene (CS₂ solubles) and carboid (CS₂ insolubles). (Inanç 1989)

The oil yield is mostly affected by the catalyst loading which shows to a certain extent that the conversion of asphaltenes to oils is a catalytic step. The selected process variables showed a positive trend with respect to the yield of hexane eluted oil which is the desired product of liquefaction.     

Slurry-phase catalytic hydrocracking of mazut (heavy residual fuel oil) using Ni-bentonite

Abstract

In this work, Ni-bentonite catalyst was synthesized through exchange method. The synthesized catalyst and the pristine clay were characterized by XRD, XRF, TGA/TDA, TEM, EDX-mapping, nitrogen adsorption-desorption at ?196?°C, H₂-TPD and NH₃-TPD. The catalytic efficiency of the dispersed nickel catalyst toward the hydrocracking of mazut (heavy residual fuel oil) under reduced pressure has been evaluated. The experimental results showed increasing yield of middle distillate fraction to 71?wt.% as the reaction temperature raised to 430?°C under pressure 2.0?MPa.     

COMPARATIVE REACTION STUDY OF METHYLCYCLOHEXANE AND 3-METHYLHEXANE IN H2 AND N2 ON Pt/Al2O3 CATALYST

ABSTRACT

The reaction of methylcyclohexane and 3-methylhexane were studied in a pulse microcatalytic reactor using H₂ and N₂ carriers on Pt/Al₂O₃ catalyst at temperatures from 350 to 500°C, contact times (W/F) of 1.25 × 10^?3–3.75 × 10^?3 g min/ml and a total pressure of 4.0 kg/cm². In N₂, there was complete conversion of methylcyclohexane to methane, benzene and toluene while similar products were produced for 3-methylhexane, albeit with diminished conversion level. In H₂, methane was produced from 3-methylhexane conversion while aromatization without demethylation was obtained in addition to some cracking for methylcyclohexane at the low temperature range (350–400°C); a higher temperature range (460–500°C) resulted in complete fragmentation for methylcyclohexane. In H₂–N₂ mixtures, the presence of N₂ of not less than 50% in the carrier gas stream yielded an aromatic catalyst at conditions where only cracking activity was previously evident. The differences in product distribution and/or product types for the two reactants in H₂ and N₂ suggest a different reaction mechanism for both reactants.     

HYDROCRACKING OF ARABIAN MIX ASPHALTENES IN THE PRESENCE OF MODIFIED RED MUD

ABSTRACT

Asphaltenes precipitated from an Arabian Mix vacuum residue were hydro-cracked in a batch autoclave at 435 and 460°C for 5-90 min. Experiments without catalyst, with modified red mud and with an industrial Co Mo/Al₂0₃ catalyst were compared. The products were fractionated into gas, naphtha, oil, asphaltenes and coke. Feed asphaltenes and several product fractions were characterised by elemental analysis, by average molecular mass and by ¹H n.mr. Due to the hydrogenation activity, both catalysts caused - with similar efficiency - the decrease of coke formation and the increase of quantity and quality of oil.     

A kinetic model for delayed coking process of Iranian vacuum residues

A four-lump kinetic model was developed for delayed coking process of Iranian vacuum residues. The feedstock and products were considered as a unique and three separated lumps, respectively, in the model. The product lumps were included gas (C₁–C₄), distillate (C₅₊ –500?°C), and coke (toluene insoluble and 500?°C+). The reactions performed in an atmospheric batch pilot plant reactor by selected feeds at three temperatures (420, 450, and 480?°C) and four residence times (10, 30, 50, and 120?min). Reactions were assumed in first order and based on Arrhenius reaction rates. Also, the kinetic model was validated by a similar feed at different conditions that showed suitable precision with experimental results.     

Synthesis and interfacial activity of petroleum sulfonate

Four petroleum sulfonates including first vacuum distillate sulfonate, second vacuum distillate sulfonate, third vacuum distillate sulfonate, and vacuum residue sulfonate were synthesized. The tensions of the petroleum sulfonates were measured. It shows that the third vacuum distillate sulfonate can produce ultralow interfacial tension when the concentrations are higher than 0.010%. Synergism between Na₂SO₄ and CaCl₂ (or MgCl₂) in the formation water was proved, which is crucial to reduce the tension. Moreover, synergism between the second and third vacuum distillate sulfonates occurs. This work is useful for enhanced oil recovery.     

PRODUCTS FROM FLASH PYROLYSIS OF A TURKISH LIGNITE IN A FREE-FALL REACTOR UNDER VACUUM

ABSTRACT

Flash pyrolysis of a Turkish lignite under vacuum in a free-fall reactor was examined at a temperature range of 400 - 800 °C. Gaseous products were analysed with an on-line GC equipped with a manuel injection valve. Solvent fractionation was applied to the liquid product to separate preasphaltenes, asphaltenes and oils fractions. Two particle distributions of the lignite were used: ?0.315+0.2 mm and ?0.1 mm. The liquid yield increased with temperature up to 650 °C and, thereafter decreased for the larger particles. The maximum liquid yield, excluding pyroltic water, was found to be 8 % wt (dal) at 650 °C. In the case of the smaller particles the liquid yield increased steadily with temperature and the yield of liquid, excluding pyrolytic water, was 5.9 % wt (da) at 850 °C. The gaseous product yield also increased with temperature for both size fractions, and CO and CO₂ in the gaseous products were present in large amounts.     

Evaluation and modeling of Fischer-Tropsch synthesis in presence of a Co/ZrO2 catalyst

Abstract

The present work focused on the application of response surface methodology (RSM), Box–Behnken design (BBD), for prediction of products distribution of Fischer-Tropsch synthesis (FTS) using a Co/ZrO₂ catalyst in a fixed bed reactor. The effect of four independent operating variables such as reaction temperature, pressure, space velocity and H₂/CO ratio on the responses (CH₄ and C₅⁺ selectivities) in FTS were investigated. The analysis of variance (ANOVA) results showed that the suggested quadratic models could well predict CH₄ and C₅⁺selectivities. The optimized operating condition was temperature 200.73?°C, pressure 20?bar, space velocity 1662.58?h^?1 and H₂/CO ratio 1.93.     

Oxidative Dehydrogenation of Methanol on Chromium Oxide/Montmorillonite K10 Catalysts

Abstract

Methanol conversion was carried out on a mesoporous material—chromia/montmorillonite K10 (MK10)—in a pulse microcatalytic system. Methanol was converted to formaldehyde and ethylene by two different mechanisms. Methanol dehydrogenation increases by increasing reaction temperature (300–400°C) and as chromia loading decrease. On the other hand, the dehydration of methanol occurs at a higher temperature (400–500°C) and as chromia loading increase, 3–18% Cr. Redox and exposed nonredox Cr³⁺ are responsible for formaldehyde formation. There is a relationship between increased C₂H₄ production and the increase of Cr⁶⁺ phase according to the acidity of chromia catalysts 34 and 76 μL tert-Butylamine/g catalyst for 3% Cr and 18% Cr, respectively. Formaldehyde formation is diffusionally controlled at high temperatures (400–500°C) and kinetically controlled at a lower reaction temperature (300–400°C), while methanol dehydration to ethylene is surface reaction controlled at 400–500°C.     

FLOCCULATION OF ASPHALTENES IN HEAVY OIL AT ELEVATED TEMPERATURES

ABSTRACT

It has been observed that there is a dispersed phase of particles in vacuum residue that is associated with the heptane insoluble asphaltenes. The particles are in the size range of 100 Aˇ. In this paper we present rheological and small angle X-ray scattering(SAXS) data for the vacuum residue of Arabian Medium/Heavy crude oil that suggests the dispersed particles flocculate at elevated temperatures. We find the asphaltenic particles are stabilized below 200 ^° C against the attractive dispersion forces between asphaltenic particles by an adsorbed layer of non-asphaltenic molecules. However the strength of the interaction holding the adsorbed layer to the particles is only about 1.8 kcal/mole(3kT), and so this layer is dissipated as the temperature is increased. We estimate the particles are unprotected at 200 ^°C. The strength of the attraction due to the dispersion force is about 7kT in this state, and so the dispersion becomes thermodynamically unstable with respect to flocculation. Additionally, the driving force for flocculation is augmented by the formation of particles in the non-asphaltenic phase at elevated temperatures. The appearance of these particles increases the osmotic pressure, and forces the asphaltenic particles together. We suggest the asphaltenic phase formed by flocculation, well below the temperatures at which chemical reactions occur, is the precursor to the coke-producing phase in the reacting residue discussed by Wiehe.     

Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

Abstract

This study concerns the distribution, type, and structure of carboxylic acids in the 200–550°C distillates of Bohai crude oil. The acids, isolated by aqueous alcoholic sodium hydroxide, were converted into corresponding methyl esters with BF₃ as a catalyst. The chemical structure of these carboxylic acids and distribution of their various components in different distillates were studied in detail by IR, VPO, MS, and elemental analysis. The results show that the carboxylic acids in Bohai crude oil are mainly composed of naphthenic acids and branched chain fatty acids, and the content is high in distillates at about 405 and 505°C. With the increase of boiling temperatures of distillates, the content of naphthenic acids increases gradually. The ring numbers of naphthenic acids in diesel distillate are mainly 1–3, and those in lubricant distillate are mainly 1–6.     

STUDIES ON SLUDGE FROM STORAGE TANK OF WAXY CRUDE OIL PART - I : STRUCTURE AND COMPOSITION OF DISTILLATE FRACTIONS

ABSTRACT

Tank bottom sludge from storage tanks of Bombay High crude oil deposited during ten years have been studied. The yield of the sludge is approximately 0.1% wt. of the crude oil through-put. The residue boiling above 500°C amounts to over 50%. The distillate fractions collected at 50°C intervals have been analysed extensively and compared to fractions from whole crude of same boiling range. The sludge distillate are distinctly more paraffinic in nature.