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This work experimentally investigated the broad ranges of dimethyl ether (DME) additions (0–100%) to ethylene on soot formation at different scales (combustor diameter) by both optical diagnostic a...

Chemical looping ammonia generation (CLAG) is thought to be another method for clean utilization of fossil fuels, because fossil fuels can be thoroughly converted into chemical material, CO, and no...

Polypyrrole (PPy) hollow micro/nanospheres have been widely designed to encapsulate active sulfur as cathodes in lithium–sulfur (Li–S) batteries to inhibit the polysulfide shuttle effect. Here, for...

Butanol is an attractive second-generation biofuel as well as an important chemical. Production of butanol from lignocellulosic feedstock via consolidated bioprocessing has attracted increasing int...

A novel method was discussed for the preparation of petroleum-based mesophase pitch with a large domain structure and an ordered microcrystal structure. A condensation pitch with a certain amount o...

Accurate prediction of coke yield is the basis for simulation and operation of the in situ combustion process. In view of the low asphaltene content of heavy oil in China, this study established coke yield prediction models for the pyrolysis and oxidation processes of low-asphaltene heavy oil based on the coking characteristics of the main fractions, including saturates (S), aromatics (A), and resins (R). The models were verified by the experimental coke yields of heavy oils using a fixed-bed reaction system. The prediction model for the pyrolysis process included evaporation rate equations and kinetic equations for coking reactions. Besides the same parts with pyrolysis, the model for the oxidation process included the kinetic equation of coke oxidation. The evaporation rate equations were determined by fitting the mass loss rate in the evaporation range of thermogravimetric analysis (TGA) pyrolysis results with a maximum error of 6%. The kinetic parameters for the conversion of each fraction to the coke precursor were determined by the isoconversional method based on TGA results of the separated SAR fractions. Considering the interactions among fractions during oxidation, this study included mixtures of SAR fractions as the samples and obtained the mass loss results of a single SAR by subtraction. The activation energies of SAR pyrolysis range from 99 to 180 kJ/mol and those of SAR oxidation range from 92 to 130 kJ/mol. The kinetic parameters of coke from the coke precursor were obtained by temperature-programmed coking data of a prepared intermediate, with an activation energy of 177 kJ/mol in an inert atmosphere and 65 kJ/mol in an oxidizing atmosphere. The kinetic parameters of coke oxidation were derived by the isothermal kinetic method in TGA, with an activation energy of 136 kJ/mol. The experimental coke yields of Fengcheng and Hongqian heavy oils under various pyrolysis and oxidation conditions were predicted by this model with an error around 10%, indicating that this model could be successfully applied to the prediction of the coking process of low-asphaltene heavy oil under complex conditions.

Three difunctional ethyl esters (DFEEs), including ethyl 16-hydroxyhexadecanoate, ethyl (Z)-18-hydroxyoctadec-9-enoate, and diethyl (Z)-octadec-9-ene-1,18-dioate, were isolated as nearly pure compo...

In situ combustion is an enhanced method to recover heavy oil. The formation and oxidation of coke are crucial to promote the combustion front. Heavy oil from China and montmorillonite, a major type of clay, were used as samples in this study. The thermogravimetric analyzer (TGA) was applied to temperature-programmed oxidation/pyrolysis experiments to study the effect of montmorillonite on the thermal conversion characteristics of heavy oil. A fixed-bed reactor was then used to obtain coke and study the effect of montmorillonite on coke properties. The characteristic temperatures of thermal conversion decreased with montmorillonite in the oxidizing atmosphere but remained unaffected in the pyrolysis atmosphere. The fuel deposition increased in both atmospheres because of montmorillonite’s strong adsorption. In the oxidizing atmosphere, the presence of montmorillonite obviously promoted the progress of coke formation and increased coke yield. The content of O was increased, and the contents of C and H were...

In this paper, a single particle (400–500 μm) co-combustion method was proposed to study the co-combustion characteristics of sewage sludge (SS) and bituminous coal (BC) in air and oxy-fuel conditions. In addition, the thermogravimetric analysis experiments were also carried out for comparison. The results from single particle combustion experiments indicate that SS and BC and their blends all exhibit a two-stage combustion process. With the blending ratio of SS increasing from 0–50 wt %, the volatiles flame of blended fuel particle becomes shorter and smaller, while the average temperature of volatiles flame increases from 1332.4 to 1399.2 °C, which suggests a synergistic effect exists. Owing to the extremely low fixed carbon content of SS, the average temperature of char combustion of the blended fuel particles decreases from 1472.3 to 1281.3 °C. The ignition delay time and volatiles burnout time of the blended fuel particles obviously decrease with the addition of SS. Replacing N2 by CO2 extends the ig...

Coking of heavy oil plays a key role in in situ combustion, which is affected by conversion conditions. In this study, a fixed-bed reactor and a pressurized reactor were used to thermally transform a heavy oil sample from China into coke under different atmospheric conditions, heating rates, and pressures. Elemental composition and surface functional groups were studied by an elemental analyzer and diffuse reflectance Fourier transform infrared spectrometer, whereas oxidative activity and coke yield were characterized by a thermal gravimetric analyzer. Results showed that yields, characteristics, and oxidative activities differed between the cokes produced in inert and oxidizing atmospheres. Compared with an inert atmosphere, an oxidizing atmosphere presented lower coke formation temperature and higher yield. In comparison with inert atmosphere, the coke produced in oxidizing atmosphere contained more oxygen, thus increasing the amount of surface functional group, but its oxidative activity was poorer. In...

In this work, the mesophase pitch was generated from the thermal condensation of the petroleum aromatic-rich fraction. Tetrahydronaphthalene as a hydrogen donor was selected to treat the condensation intermediate using the in-process hydrogenation method. The objective of this work was to investigate the effects of in-process hydrogenation on the formation and development of mesophase structures. Results showed that the intermediate after in-process hydrogenation possessed a more-uniform molecular structure and narrower molecular-weight distribution, compared to the blank intermediate without in-process hydrogenation, which was attributed to the increasing content of naphthenic structures in the intermediate. From the characterization analysis of carbonized products, it can be found that the in-process hydrogenation of the condensation intermediate was conducive to the generation of mesophase pitch with a large domain structure, narrow molecular-weight distribution, low softening point, and carbon residue.

Soot has received considerable attention since it is a major pollutant in exhaust gas from fossil fuel combustion and it causes adverse climate and health effects. This work focused on soot morphology, nanostructure, and reactivity variations regarding the soot collected in different flame configurations of n-butanol-doped ethylene inverse diffusion flame (IDF) and normal diffusion flame (NDF) at different heights above burner surface (HAB = 20, 30, and 40 mm). The effects of flame configuration and soot aging on structural and reactivity characteristics were analyzed with emphasis on the differences of young and mature soot generated in IDF and NDF without and with n-butanol addition at specific positions, respectively. The effects of fuel-side n-butanol addition on IDF and NDF soot structures and reactivity were also evaluated. The soot obtained using thermophoretic sampling technique was analyzed by transmission electron microscopy (TEM) to investigate soot morphology evolutions along the centerline an...

Structural modifications of petroleum pitch and its sub-fractions induced by mild air-blowing modification have been monitored by elemental analysis, average molecular weight, Fourier transform infrared spectrometer (FTIR), 1H nuclear magnetic resonance (1H-NMR) and carbon residue. Combined with the investigation into carbonization behaviors of as-prepared oxidized pitch, the relationship between oxidized modification and carbonization behaviors has also been discussed. With the air blowing treatment processing, average molecular weight and oxygen content grow rapidly in petroleum ether-insoluble fraction of air-blown pitch in comparison with those of corresponding petroleum ether-soluble fractions, which gradually enlarges distinction in carbonization reactivity and mutual solubility between this two sub-fractions. As a result, although the yield of carbonized residue is dramatically promoted from 36.1wt% to 64.5wt% during the direct thermal carbonization process, the air blowing treatment produces adver...

In this study, the aromatic-rich fraction from heavy oil was modified by polyacrylic acid and oleic acid to obtain the modified raw materials which were used for producing mesophase pitch via polymerization reaction. First, the properties of modified feedstocks were analyzed by Fourier transform infrared spectrometry (FTIR), simulated distillation, and elemental analysis. The optical texture and molecular and microcrystal structure of the mesophase were characterized by the techniques of polarized optical microscopy, FTIR, 1H nuclear magnetic resonance, X-ray diffraction, and Raman spectroscopy. The influence of alkyl structures contained in modified feedstocks on the preparation of the mesophase was studied. The results suggested that the amounts of alkyl chains in modified raw materials increased first and then decreased with raising the amount of the additives. The short and long alkyl chains in mesophase pitches from modified feedstocks were resulted by treatment of polyacrylic acid and oleic acid, re...

A novel synthesis method was developed to prepare a silica-supported monoclinic molybdenum dioxide (MoO2/SiO2) catalyst via calcination of molybdenum disulfide (MoS2)/SiO2 in N2 flow with 0.1 vol % O2. MoO2/SiO2 was employed as a catalyst for sawdust hydroliquefaction in ethanol at 320 °C under an initial H2 pressure (IHP) of 2–6 MPa, and the bio-oil yield as high as 72.3% was obtained under an IHP of 6 MPa. The high catalytic activity of MoO2/SiO2 should be attributed to the efficient cleavage of H2 on the surface of highly dispersed MoO2, which shows an unusual metallic characteristic. The obtained bio-oil was analyzed with gas chromatography/mass spectrometry (GC/MS), and the main organic compounds detected by GC/MS were phenolics and ethyl esters.

Two feedstocks (LPA and HPA) obtained from modification of naphthenic vacuum residues were selected to prepare mesophase pitch by direct thermal treatment. The influence of reaction temperature, soaking time, reaction pressure, and molecular structures of the feedstock on mesophase development was systematically investigated by analyzing variations in carbonization yield, carbon residue, quinoline insolubles (QI) content, density, optical textures, crystal structure, and surface morphology of derived products. It is found that the mesophase development and the properties of resultant mesophase products were closely related to the molecular structure of the original materials and preparation conditions. Compared with LPA, HPA was the preferable feedstock for thermal treatment because of its high degree of aromaticity and a large proportion of naphthenic carbon, and the resultant product obtained under the optimum conditions showed large flow domain mesophase, fewer alkyl side chains, and a high degree of m...

A comprehensive compositional analysis was conducted on biofuel obtained from woody biomass hydroliquefaction in supercritical ethanol with a dispersed Ni-based catalyst. Gas chromatography–mass spectrometry (GC–MS) and 1H nuclear magnetic resonance (NMR) were used to analyze the bio-oil compositions, and the results indicated the presence of carboxylic acid, ethyl ester, aldehyde, ketone, phenol, and its derivatives. As a result of the inherent limitations of these techniques, an intensive compositional characterization of bio-oil was accomplished through Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results revealed that the dominant oxygen-containing compounds were O2–O13 with double bond equivalent (DBE) values of 1–20 and carbon numbers of 10–25. The minor N1Ox class species with 4–15 carbon numbers and 10–35 DBE were also detected. The use of FT-ICR MS provided an in-depth compositional analysis of liquefaction-derived oil and would improve the understanding of biocrud...

Two modified pitches with softening points of 70 °C (LPA) and 110 °C (HPA) produced from modification of naphthenic vacuum residue were cocarbonized with polystyrene (PS), respectively, and the mesophase pitches were obtained. The effects of reaction time, PS addition, pressure, and properties of raw materials on cocarbonization behavior were analyzed by H/C, quinoline insoluble content (QI), carbon residue value, density, polarized optical images, X-ray diffraction pattern (XRD), scanning electron microscopy (SEM) analysis, Fourier transform infrared (FTIR) spectra, and 1H nuclear magnetic resonance (1H NMR) analysis. Comparing with HPA, the cocarbonization process showed more suitable for LPA to prepare the mesophase pitch due to the favorable occurrence of radical chain transfer reactions between LPA and PS components which contributed to the existence of aliphatic side-chains and naphthenic structures in mesogens as well as the formation of a well-developed mesophase pitch. Mesophase pitch with larger...

Comparative studies in carbonization behaviors of petroleum pitch (SS70 pitch) and SS70-pitch–additive mixtures were conducted to develop a better understanding of the modified mechanisms of additives. The carbonization of solvent fractions in SS70 pitch was also investigated to reveal the relationships among solvent fractions and the additives. The characterization of resultant solid products by X-ray diffraction and scanning electron microscope analysis showed that samples obtained from co-carbonization of SS70–aromatic oil (P1) and SS70–aromatics enriched fractions of FCC slurry (P2) mixtures respectively had higher stacking layer numbers of mesogens and flatter morphology than those of specimens produced by carbonization of SS70 pitch and SS70–deasphalt oil (P3) mixtures. Adding additives P1 and P2 into SS70 pitch lowered not only the rates of carbonization but also the aromaticity and size of aromatic molecules in toluene insolubles formed in the early stage of carbonization, both jointly contributin...

In this work, a series of solid desulfurizers were prepared via loading of an inorganic alkali on activated carbon (AC). The optimal synthetic procedure of the solid desulfurizer is to pretreat AC with nitric acid (68.0 wt %) for 4 h and then impregnate the sample in a 0.02 g/mL NaHCO3 aqueous solution at 35 °C for 2 h. Finally, this solid adsorbent desulfurizer was calcined at 500 °C for 4 h, and referred to as NC-AC. This solid desulfurizer was used to treat Saudi Arabian crude oil with a mass ratio of 30:1 (crude oil:NC-AC) at 55 °C for 3.5 h. A desulfurization efficiency as high as 32.4 wt % was achieved with optimized NC-AC. The NC-AC samples had larger pore diameters and evenly distributed alkali leading to high desulfurization efficiency. The desulfurization mechanisms of the AC supported desulfurizer were analyzed, indicating that both physical and chemical adsorption occurred on the desulfurizer. This desulfurizer also has good performance to adsorb thiophenes, alkylthiophene, and benzothiophenes...

The SnSb intermetallic compound was synthesized by chemical precipitation with NaBH4 as a reducer, and then it was applied in the electrodesulfurization of Saudi crude oil as functional desulfurization material. The prepared SnSb intermetallic compound was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS). Additionally, the raw material and treated oil were analyzed through gas chromatography–pulsed flame photometric detector (GC–PFPD) and gas chromatography–mass spectrometry (GC–MS). The results showed that the SnSb intermetallic compound was restored with NaBH4 with a larger particle size, lower surface area, lower crystallinity, and “brick-shaped” structure. The desulfurization efficiency for sulfocompounds with a small molecular weight is higher. It should be especially noted that benzonaphthothiophene was hardly removed by traditional hydrogenation desulfurization, whereas it could be subtracted partly via electrochemical adsorption...

The raw oils P1, P2, and P3 with different properties from a naphthenic base vacuum residue were used for preparing the mesophase pitch through high-pressure thermal treatment. In the first, 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and vapor pressure osmometry (VPO) were employed to characterize the structural parameters of the raw materials. Development of the anisotropic mesophase was monitored by polarized light optical microscopy. Four n-heptane-soluble (HS), n-heptane-insoluble/toluene-soluble (HI-TS), toluene-insoluble/pyridine-soluble (TI-PS), and pyridine-insoluble (PI) fractions of the product were obtained by extracting with heptane, toluene, and pyridine. The molecular and crystal structure was analyzed by FTIR, 1H NMR, and X-ray diffraction (XRD). The effects of the feed composition on the formation of the mesophase pitch were investigated. The results showed that the structure of the raw material plays a very important role on mesophase pitch format...

The chemical effects of CO2 addition on premixed laminar low-pressure dimethyl ether and ethanol flames were studied by comprehensive numerical analysis from fuel-lean to fuel-rich conditions. Added CO2 is assumed as normal reactive CO2 and fictitious inert CO2 to assess the chemical effects of CO2. The dilution and thermal effects of CO2 addition decrease C2H2 mole fractions in ethanol flames instead of DME flames, but the chemical effects can reduce C2H2 mole fractions in both DME and ethanol flames at all equivalence ratios, which reveals that C2H2 formation can be suppressed chemically by CO2 addition. The chemical effects have a weak influence on formaldehyde formation in both DME and ethanol flames. The CO2 chemical effects only result in a slight decrease of acetaldehyde peak mole fractions in DME flames but not in ethanol flames at all equivalence ratios. Mole fractions of the H radical decrease because of the chemical effects of CO2 addition by shifting the equilibrium of CO + OH = CO2 + H in bot...

The composition, structure, and colloidal stability of hydrocracked products at various hydrogen pressures were analyzed to investigate the role of hydrogen pressure in slurry-phase hydrocracking of Venezuela heavy oil. Experimental data showed that the formation of gas, naphtha, and coke was suppressed by a high hydrogen pressure during the slurry-phase hydrocracking. In addition, the maximum of light oil per coke ratio was observed at 8 MPa of hydrogen. The desulfurization and denitrogenation were promoted by the increase of hydrogen pressure. However, the influence of hydrogen pressure on the desulfurization rate was reduced at higher pressure, while the influence on the denitrogenation rate was still obvious. With the increase of hydrogen pressure, the Conradson carbon residue (CCR) of the vacuum residue (VR) product decreased. Meanwhile, the coking inducing period of the atmospheric residue (AR) product prolonged, which means that the colloidal stability of the AR product was enhanced by a high hydro...

Thermal hydrocracking and slurry-phase hydrocracking of Karamay vacuum residue (KLVR) were studied, and the hydrocracked products were analyzed by gas chromatography (GC) and a paraffins, olefins, naphthalenes, and aromatics (PONA) composition analysis system. The effects of the temperature and initial hydrogen pressure on the isomerization reaction in heavy oil slurry-phase hydrocracking were investigated. Experimental data revealed that the conversion of KLVR increased as the temperature and initial hydrogen pressure increased in both thermal hydrocracking and slurry-phase hydrocracking. Hydrogen consumption of slurry-phase hydrocracking increased with the increase of the temperature and initial hydrogen pressure, while hydrogen consumption in thermal hydrocracking was negligible. Two impact indexes RG′ and RN′ were proposed to study the isomerization reaction in heavy oil slurry-phase hydrocracking. The results indicated that a high temperature and high initial hydrogen pressure enhanced the isoparaffi...

The effect of different solvents on the hydro liquefaction of sawdust with ionic liquid nickel catalyst was investigated. Subsequently, effects of different parameters on the liquefaction behavior of sawdust were explored with the suitable solvent. The optimized results with bio-oil yield of 58.51% were obtained using ethanol solvent at 320 °C and 10 min with solvent/biomass of 10 mL/g. The higher heating values of the bio-oil was 26.02 MJ·kg–1, which was higher than that of sawdust. According to the GC–MS analysis, the major compound in light oil was ethyl esters, and the components of heavy oil were mainly consisted of ethylbenzene other benzene derivatives.

Removing solid impurities inside slurry oil from residual fluidized catalytic cracking (RFCC) is critical for efficient use of its aromatic hydrocarbons, and selective separation of the solid components is also an important issue of recycling valuable resources for catalyst and carbon material. Different separation methods were employed to isolate the solids and their components in the slurry oil from a RFCC unit, and the resultant solids and components were comprehensively characterized by elemental analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and energy-dispersive X-ray (EDX) analysis, etc. Results show that the content of toluene-insoluble solids in the slurry oil varies from separation methods employed. The solid components, i.e., catalyst particles and coke powders, can be sequentially separated, and the choice of an appropriate separation method is critical for accurate determination of the solid content in a RFCC slurry oil...

The nitrogen compounds in Liaohe atmospheric residue (LHAR) have been analyzed through Fourier transform infrared spectroscopy (FTIR), gas chromatography coupled with mass spectrometry (GC–MS), etc. to investigate the mechanism of reaction during slurry-phase hydrocracking. Their chemical structures have been exploited, and the experiment data revealed that the molecular weight of nitrogen compounds after hydrocracking was increased in comparison to that in crude oil in the same fraction. Basic nitrogen compounds in Liaohe light vacuum gas oil (VGO) were composed of quinolines, etc., and non-basic nitrogen compounds consisted of carbazoles, amines, etc. The contents of basic nitrogen compounds were decreased with the increase of the boiling point, but non-basic nitrogen compounds changed oppositely. Meanwhile, nitrogen compounds could be hydrocracked, and the products were transferred into some “lighter” fractions, such as diesel and VGO.

Venezuela heavy oil under various hydrogen pressures has been hydrocracked to investigate the variation of asphaltene components during reaction. Asphaltenes have been isolated from the product and analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR). The experimental data revealed that the interlamellar spacing and interchain spacing of the asphaltenes increased while the layer diameter decreased with the hydrogen pressure increasing. At the same time, the amount of aromatic carbon and alkyl carbon of the asphaltenes decreased gradually and the amount of naphthenic carbon increased. As the hydrogen pressure increased, the substitution ratio and the condensation degree parameter (HAU/CA) of the aromatic system in the periphery increased gradually and the replacement index and peri-position condensation index of asphaltenes decreased obviously.

In this paper, the distribution of nitrogen (N)-containing compounds of slurry-bed hydrocracking products are investigated. Raw materials of the products were Liaohe atmospheric residue (LHAR), whi...

The hydrogen-bonding strength of asphaltenes in Liaohe, Gudao, and Shengli vacuum residues are studied using an in situ Fourier transform infrared (FTIR) technique. The surface tension of different...

The composition and reactivity of dispersed Ni catalyst was studied for slurry-phase hydrocracking of the residue. The Ni catalyst was separated at different reaction times and characterized. It was concluded that the water-soluble salts turned into NiS and Ni3S2 after the reaction for 1 or 2 h, respectively. After 3 h of reaction, the crystal of Ni9S8 appeared in the catalyst, and after 4 h of reaction, the catalyst was mainly made up of Ni9S8. The “relative coke restraining ratio” (Cr) was introduced and used to show the coke restraining ability of Ni catalysts at different reaction times. It was concluded that the coke restraining ability of the catalyst containing different kinds of crystals was different. To acquire a higher coke restraining ability of the catalyst, the proper reaction time of residue hydrocracking with dispersed Ni catalyst is 1.0−2.0 h.

The slurry-phase hydrocracking of Karamay atmospheric residue (AR) with water-soluble dispersed catalyst was studied, and the catalyst after being separated from the reaction products was analyzed using laser Raman spectroscopy (LRS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to identify the crystal structure of the catalyst. In this paper, the catalytic functions of molybdenum, nickel, and iron were studied respectively during the slurry-phase hydrocracking while using diphenylmethane as the model compound and AR from Karamay crude as the feedstock. The test results showed that, during the slurry-phase hydrocracking of heavy oil, the metal sulfides entered into chemical reactions with the free-radical intermediate H• formed on the catalyst surface. The free-radical intermediate H• formed on the catalyst surface could react with the free radicals of large molecules and could suppress coke deposition.

A hydrocracking study of Karamay residue using a batch reactor in the presence of dispersed Ni catalysts with different sulfurization methods is reported. Using two different courses of dispersion and sulfurization, the water-solubility Ni catalyst is dispersed in heavy oil and the dispersed catalyst is separated and characterized. Results showed that the water-solubility salts turn into NiS and NiS2 at the sulfrization temperature of 300 °C, regardless whether the emulsion breaking was achieved by multiple stages or a single stage after dispersion, and while the sulfurization temperature is at 300 °C and breaking the emulsion is by one stage, the better crystal of nikel pyrite is formed and the average particle size of the crystal is smaller than breaking the emulsion by multiple stages. The colloidal sol catalytic system of nikel pyrite is also synthesized in the experiment, and the sol of nikel pyrite can be highly homodisperse in oil and can restrain coke forming effectively.

The capability to perform fast load changes has been an important issue due to the increasing commercialization of the power market. In the traditional boiler control system, the feedback signals come from the variations of the steam pressure and the steam flow, which leads to a large time delay. Therefore, a new method for the boiler control system based on radiation intensity for improving the load-following capacity of a coal-fired power plant has been developed in this paper. The system is implemented by adding the radiation intensity of the flame to the existing boiler control system as a complement. The radiation intensity obtained by the sensor can directly reflect the input heat in the boiler, with a faster response and higher sensitivity. Field tests on a 300 MW coal-fired power plant reveal that the improved boiler control system increases the load-following capacity. At the same time, the steam pressure variations are smaller as compared with those of the existing control system. 14 refs., 19 figs., 1 tab.

The technologies of slurry-phase hydrocracking of heavy oil and the latest development of dispersed catalysts were reviewed. Catalysts for slurry-phase hydrocracking of heavy oil have undergone two development phases, that is, heterogeneous solid powder catalysts and homogeneous dispersed catalysts. The homogeneous dispersed catalysts are divided into water-soluble dispersed catalysts and oil-soluble dispersed catalysts. Solid powder catalysts have low catalytic activity, which will produce a large number of solid particles in bottom oil; thus it is difficult to dispose and utilize. Dispersed catalysts are highly dispersed and have greater surface area to volume ratio. Therefore, they show high catalytic activity and good performance. They are desirable catalysts for slurry-phase hydrocracking of heavy oil.