Abstract: The behaviors of mild liquefaction of a lower rank coal (HL lignite) were investigated using a tube bomb reactor with respect to the influence of reaction temperature, solvent, initial pressure, atmosphere and catalyst. TPD-FID(temperature programmed decomposition-flame ionization detector)and FT-IR were used to study the properties of liquefaction residues (hexane insoluble part). The gel permeation chromatography, synchronous fluorescence and infrared spectroscopy were used to study the structure characteristics of asphaltenes (A) and preasphaltenes (PA) produced. The results show that the notable liquefaction of HL lignite starts at about 350℃. The increase of liquefaction yield increases with the increase of the temperature. As the condensation reaction becomes significant at the higher temperature (450℃), the liquefaction yield starts to decline. The solvent can significantly improve the yields of A+PA. The increase of reaction pressure and the addition of catalysts mainly lead to an increase of Oil+Gas (O+G) yield. The liquefaction residue (hexane insoluble) obtained under mild conditions has a higher pyrolysis reactivity than its parent coal. When the liquefaction temperature is higher than 300℃(350℃), the molecular weight and the paraffinic characteristics of asphaltene (preasphaltene) decrease with liquefaction temperature.
Abstract: Adjustment of coal ash fusibility of high fusion point coal has been attracted by attention of many researchers in coal gasification and combustion. The effect of Mg2+ and Na+ on the fusibility behavior of the high fusion temperature coal ash from Yangquan Guzhuang was studied in this paper, using the method of adding different amount of MgO and Na2CO3 (5%~25%) to the coal ash. The result shown that the ash fusion temperature monotonically decreases with increasing addition amount of MgO, while the ash fusion temperatures exhibit low valley and reach the minimum when the addition amount of Na2CO3 is 15%. Investigated by XRD, mullite and cristobalite are detected in the Yangquan Guzhuang coal ash, which results in the ash fusion temperature of the coal ash higher than 1 750℃. Additions reacting with silicate minerals can form more low-melting eutectic minerals, such as cordierite and nepheline, etc. Meanwhile, the additions of Mg2+ and Na+ cause non-bridged oxygen and oligomers increasing, then the ash fusion temperature reduce. Ternary phase diagram and SEM micrograph confirm that the local clustering of partial elements and reunited phenomenon of coal ash under high temperature condition result in the different effect of Mg2+ and Na+ on the coal ash fusibility behavior.
Abstract: Four coal samples including Shenmu coal from Shaanxi, Nalingou coal from Inner Mongolia, Yangchangwan coal from Ningxia and Nantun coal from Shandong were prepared for the research on the rheological properties of coal ash at high temperatures. The high temperature rotational viscometer was used to study the effect of shear rate on the shear stress and viscosity of coal ash. The results indicate that the coal ash slag falls into a Newtonian fluid when the temperature is above the liquidus temperature, while it gradually turns into non-Newtonian fluid when the temperature is below the liquidus temperature. Shenmu and Yangchangwan coal ash owns the plastic and shear-thicking characteristics, while Nalingou and Nantun coal ash has the pseudoplastic and shear-thinning characteristics. Meanwhile, the crystals are formed with the decrease of temperature, which makes the yield stress increase and the flowability of coal ash slag decrease.
Abstract: Reduction of NO and N2O with the simulated pyrolysis gas of NH3-CO-H2-CH4-O2 mixture was experimentally studied in an ideal plug flow reactor. The effects of temperature, excess air number λ, concentration of CH4, CO, H2, NH3 in the simulated pyrolysis gas, concentration of NO and N2O in the simulated flue gas on reduction of NO, N2O and total nitrogen conversion efficiency were experimentally investigated. The results show that adding combustible or reducing species of CO, H2, CH4 into NH3 can decease about 150~200 K of temperature range or window for reducing NO, the obtained optimal temperature range of reducing NO is in a range of 1 073~1 223 K. The excess air number λ or oxygen content in NH3-CO-H2-CH4-O2 mixture shows an important influence on reduction of NO and N2O. When the excess air number λ is controlled as 0.6, i.e., similar to the case of fuel-rich, the maximum decomposition ratio of NO and N2O in the simulated flue gas reaches 60.6% and 100%, respectively. When the excess air number λ is kept at 0.6 in a temperature range of 1 073~1 223 K, higher concentration of CH4, CO, H2 in the simulated pyrolysis gas can result in an effectively decomposition of N2O, but lead to an increase of NO; however, higher conversion efficiency of NO can be achieved under the condition of increasing the concentration of NH3 in the simulated pyrolysis gas.
Abstract: The coal gasification rate is the limiting step during the chemical looping combustion (CLC) process. The effects of Na- and Ni-based additives loaded on the iron ore oxygen carriers on the chemical looping combustion (CLC) of coal were investigated in a fluidized bed. The influences of temperature, loading and cycle number on the performance of compound oxygen carriers were evaluated. The catalytic effect of Na is found to be higher than that of Ni at 920℃. The rate of reaction is enhanced with increasing the loading of Na and Ni. The peaks of all the exit gas concentration appear earlier and in the later stage the decay rate of that becomes larger. The concentration of CO in the exit gas is obviously decreased, whereas that of CO2 and H2 is increased. With a 6% loading of Ni, the catalytic effect of Ni on the carbon conversion is remarkable at 960℃, in which the carbon conversion is up to 92.7% that is about 15.5% higher than that using the iron ore. However, the effect of Ni on the carbon conversion is not obvious at 800~920℃. Compared with Ni, Na shows an obvious catalysis on the coal combustion of CLC in the whole experimental temperature region (800~960℃). The scanning electron microscope (SEM) and the energy-dispersive X-ray (EDX) analysis show that there is a severe loss of Na on the surface of used Na-based iron ore, but a less loss of Ni on the surface of used Ni-based iron ore.
Abstract: The mechanism of methyl indan formation during tetralin pyrolysis was investigated by using the density functional theory (DFT). The results showed that 1-methyl indan is the main conformation of methyl indan products from tetralin pyrolysis. As the main route of 1-methyl indan formation during tetralin pyrolysis, β tetralin radical was first formed through H abstraction by radical species from tetralin, which then endures a ring contraction reaction to form 1-methyl indan. High temperature can promote the formation of 1-methyl indan, but has little effect on the formation routes of 1-methyl indan.
Abstract: The process of bio-oil pyrolysis/gasification and gas evolution characteristic was studied using a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Pyrolysis/gasification of bio-oil and its fractions were also performed in a fixed bed. As a result, the process of bio-oil pyrolysis/gasification can be divided into two stages. The first is volatilization and pyrolysis of the light compounds at low temperature and the second is cracking and polymerization of the heavy compounds at high temperature. The values of activation energy are 35~38 kJ/mol in the first stage and 15~22 kJ/mol in the second stage, respectively. With temperature increasing, the conversation of pyrolysis/gasification grows higher and the yield of synthesis gas (syngas) increases. However, the calorific value of the gas has an inverse correlation with the temperature. In comparison, the light fraction (LF) makes more contribution to the overall H2 release; while CO and CH4 are mainly generated from the heavy fraction (HF).
Abstract: Visbreaking and hydrogen donor visbreaking of Venezuelan atmospheric residue were evaluated in an autoclave. The results show that hydrogen donor employ in visbreaking process is able to inhibit gas production, coke formation and asphaltene formation of residua in the thermal conversion process. To be specific, gas and coke yield in hydrogen donor visbreaking are less than that in visbreaking by 0.5%~1.2% and 0.02%~0.98% respectively, and asphaltene content of its residual oils is less than that of visbreaking by 0.6%~1.3%. With the reaction time increasing from 5 to 20 min at 425℃, the total and net viscosity reduction rate of hydrogen donor visbreaking process varies in 46.1%~54.8% and 10.2%~33.0%, respectively. The optimum reaction condition for hydrogen donor visbreaking process is obtained at 425℃ for 5 min. Under this condition, the properties of hydrogen donor visbroken oil are as follows: the spot test rates NO. 1 according to reference spot description in ASTM D4740, the kinematic viscosity measured at 50℃ is 185.5 mm2/s and the net viscosity reduction rate is 26.4%, which meet the basic requirements of transportation.
Abstract: Field tests of underground heavy oil catalytic aquathermolysis were carried out in Shengli oilfield, the average period oil increment for 5 test wells reached to 653 t, and the viscosity of heavy oil was reduced by 79.8%, and still decreased by more than 62% after 14 weeks. The chemical and physical properties of heavy oil before and after the reaction were investigated using DV-III Ultra-Brookfield rheometers, Elementar Vario EL III elemental analyzer, Knauer K-700 Vapor permeability tester, Agilent 6890N gas chromatograph and EQUINOX 55 Fourier transform infrared spectrometer,etc. The results indicate that the heavy oil viscosity and average molecular weight are decreased and the content of resin and asphaltene is reduced after the reaction. The H/C ratio of heavy oil and the content of saturate and aromatic are increased. The amount of heteroatom in heavy oil is also decreased after the treatment. The reaction of underground heavy oil catalytic aquathermolysis is mainly affected by the catalyst system, high temperature water and reservoir mineral, in which the catalyst is the key control factor, and the hydrogen donating accelerator and dispersing agent can improve the cracking. In addition, the acid-base properties of water under high temperature and the reservoir mineral can promote the reaction. During the aquathermolysis, many reactions including the removal of alkyl side chain, the molecular chain isomerization, the hydrogenation, the ring opening, the ring closing and the desulfuration are involved, which can lead to the reduction of viscosity and improvement of heavy oil quality. The results suggest that the underground heavy oil catalytic aquathermolysis is feasible in field use.
Abstract: The mechanism of oxidative carbonylation of methanol to dimethyl carbonate (DMC) over Cuβ catalyst was investigated by using in situ DRIFTS; the adsorption of single methanol, carbon monoxide and DMC as well as their mixtures on the Cuβ catalyst were considered. The results indicated that methoxide species are formed when methanol is adsorbed on the catalyst due to presence of CuO<em>x. Only one type of active sites that are located in the six-membered ring of β zeolite is found, over which adsorbed methanol can be oxidized to methoxide and water. DMC is adsorbed on the catalyst through the contact of the oxygen atom in carbonyl group with the active sites. There were two pathways for the oxidative carbonylation: by the mono-methoxide pathway, carbon monoxide can react with mono-methoxide species to form monomethyl carbonate (MMC) and MMC then reacts with methoxide to form DMC, or by the di-methoxide pathway, DMC is formed through inserting of carbon monoxide in the di-methoxide species; latter one is more favorable over the Cuβ catalyst.
Abstract: A series of Sr-Co/Al2O3 catalysts were prepared by co-impregnation method using γ-Al2O3 as the support. The effect of strontium promoter on the catalytic performance of Co/Al2O3 catalyst for partial oxidation of methane (POM) to synthesis gas was studied. The catalysts were characterized by some physicochemical characterizations such as N2 physical adsorption, X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and thermogravimetry (TG). The results show that both Co/Al2O3 calcined at 700℃ and Sr-Co/Al2O3 calcined at 800℃ exhibit low activity and deactivate at the initial stage of POM reaction. The addition of above 2% mass fraction of strontium will greatly enhance the activity and stability of Co/Al2O3. Two types of Co species were identified on the fresh calcined catalysts. One is Co3O4 which weakly interacts with Al2O3 (easily reduced by H2) and the other is the spinel CoAl2O4 (non-catalytic performance) which strongly interacts with the support. During the course of calcination, strontium can react with Al2O3 to form Sr4Al14O25 which will restrain the generation of the CoAl2O4 species and promote the stability and activity of catalysts. Without strontium promoter, CoAl2O4 is easy to be formed over Co/Al2O3 in the POM reaction. However, the formation of CoAl2O4 cannot be avoided with the addition of limited strontium when the calcination temperature is over 800℃.
Abstract: Gallium species were introduced into ZSM-5 molecular sieves through three different measures, i.e. hydrothermal synthesis, impregnation, and ion exchange. The gallium-containing ZSM-5 molecular sieves were characterized by XRD, SEM, FT-IR, NH3-TPD, ICP, XPS and N2 sorption. The effects of silica source and the content and state of gallium species on their structure, acid property, and catalytic performance in the aromatization of methanol were investigated. The results indicated that the silica source (silica white, tetraethyl orthosilicate, and silica sol) exhibits significant effects on the crystal size and the state of gallium species, and thus influences the catalytic activity and stability of the gallium-containing ZSM-5 molecular sieves in methanol aromatization considerably. There are three kinds of gallium species, i.e. framework Ga, Ga2O3 species on the crystal surface, and non-framework Ga species with strong interaction with the framework oxygen. The framework gallium species in the tetrahedral structure offers the acidic sites of the molecular sieves, while the non-framework gallium acts as the active sites for methanol aromatization. The proper amounts of non-framework gallium species matched with the acid sites can promote the formation of aromatics.
Abstract: The Cu/ZnO/Al2O3/Cr2O3+H-ZSM-5 performances for hydrogen production during dimethyl ether steam reforming (DME SR) were investigated,which was prepared by the co-precipitation coupling with mechanical mixing method.Meanwhile, the effect of calcination temperature on the physicochemical properties of catalysts were studied by thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller, and H2 temperature-programmed reduction.It was revealed that Cu/ZnO/Al2O3/Cr2O3 catalyst was decomposed at 400℃ to form CuO and sponel phase that played a key role in separating the Cu during the reaction.Under lower calcination temperatures,the catalyst was incompeletely decomposed.Increasing the calcination temperature to over 500℃ caused severe sintering of CuO and facilitated the formation of spinel phase, which led to a significant decrease in the number of active sites.When the calcination temperature was controlled at 400℃, the biggest DME conversion rate of 92.9% and hydrogen yield of 76.5% was reached.
Abstract: The TiO2-Al2O3 complex support was prepared by the sol-gel method. A nickel phosphide catalyst, Ni2P/TiO2-Al2O3 with citric acid (CA) as chelating agent, was prepared by the impregnation method. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption specific surface area measurements (BET), thermogravimetry-differential thermal analysis (TG-DTA), temperature programmed reduction (TPR) and transmission electron microscope (TEM). The effects of different chelating agents and CA addition for dibenzothiophene (DBT) hydrodesulfurization (HDS) were studied. The result showed that the addition of appropriate amount of CA into the catalyst can enrich the pores of Ni2P/TiO2-Al2O3 catalyst, increase the surface area, which made better pore structure, higher dispersion of metal active component and more uniform size of the active component. CA can weaken the interaction between the active phase and the support, resulting in an apparent decrease in reduction temperature for nickel and phosphorus precursor as well as promotion of the formation of the Ni-P-O active phase. At reaction temperature of 360℃, pressure of 3.0 MPa, hydrogen/oil ratio of 500(volume ratio), liquid hourly space velocity of 2.0 h-1 and reaction time of 4 h, the initial dibenzothiophene conversion was 99.5% and stabilized at about 95.0% during 48 h reaction.
Abstract: Supported Co-Mo catalyst was prepared by impregnation-precipitation method using modified activated carbon as carrier and urea as precipitant.Catalytic activity of catalyst was studied by using the reduction of SO2 by CO.Under optimum reaction conditions (sulfidation temperature 500℃; GHSV=7 000 mL·g-1·h-1;CO/SO2 mol ratio =2:1; reaction temperature 450℃), the best catalytic activity and selectivity were obtained for Co-Mo catalyst with calcination temperature was 500℃ and Co/Mo mol ratio =0.45. Catalyst samples were characterized by X-ray powder diffraction (XRD) in order to relate the phase composition to the activation behavior and catalytic performance.The active phases of catalyst were detected as CoS2 and MoS2,and the formation of them were greatly dependent on the sulfidation temperature.And the catalytic activity of cobalt molybdenum catalyst decreased less than 1% after the reaction lasted for 24 h.
Abstract: A series of titania-alumina mixed oxide with different amount of γ-Al2O3were prepared by sol-gel methods, which were loaded by V2O5 and WO3 to obtain several SCR catalysts. Surface properties of those samples were studied by various characterizations techniques, like XRD, BET, H2-TPR and HRTEM. The catalytic performance for the selective catalytic reduction of NO with NH3(NH3-SCR)and the effect of SO2 in the simulated smog on the catalytic activity were investigated as well. It is found that the synergy between γ-Al2O3 and TiO2 can improve effectively the catalytic performance of V2O5-WO3/TiO2-γ-Al2O3 catalysts effectively and broaden the temperature window of SCR activity as well as strengthen the resistance to SO2 poisoning. In particular, the V2O5-WO3/TiO2-15% γ-Al2O3 sample exhibited 80% NO conversion in the wide temperature range of 310~460 ℃.All the characterization results show that γ-Al2O3 is in a well-dispersed state on the surface of TiO2; the composite support has a large specific surface area and the binary oxide possesses a comparatively strong redox property.
Abstract: Conventional and functional imidazole-based ionic liquids (abbr. ILs) were mixed based on their advantage and disadvantage on CO2 reduction. Additionally, CO2 absorption effect and regeneration performance of imidazole-based IL mixtures were discussed. It was showed that imidazole-based IL mixtures had good fluidity and smooth of transferring CO2. It had better absorption capacity of CO2 for the mixtures of [bmim][BF4] (or [bmim][Tf2N]) and [NH2e-mim][BF4] than the single IL, and lower absorption capacity for the mixtures of [bmim][CH3CO2] and [NH2e-mim][BF4] than [bmim][CH3CO2]. While the cation of conventional imidazolium ILs became longer and the mixtures could absorb CO2 more obviously, more strong effect was shown on CO2 absorption with the anion [Tf2N] than the anion [BF4] for the conventional imidazolium IL. CO2 absorption capacity of the imidazole-based IL mixtures had maintained 75%~85% of the initial capacity during 10 times of the absorption/regeneration cycles, while the quality of the regeneration was unchanged.
Abstract: In order to clarify the adsorption characteristic of activated coke under complex atmosphere of flue gases, a series of tests were conducted with a bench-scale fixed bed reactor. The simulated flue gas was prepared by mixing main composition of flue gas with mercury vapors generated through permeation tube. The surface properties were characterized by FT-IR. The results show that the performance of mercury removal is related to the surface chemistry of activated coke,and the oxygen-containing functional groups are the important factor affecting the adsorption and catalysis of Hg0. The adsorption performance of Hg0 with activated coke is influenced by SO2 obviously and inhibition is observed in the removal process. With increasing concentration of SO2, from 400, 855 to 1 520 mL/m3, the concentration of Hg0 at the outlet of the reactor increased from 36, 43 to 48 μg/m3. The complex impact of NO on the adsorptive capacity of Hg0 is found that NO with lower concentration promotes the adsorption of elemental mercury while inhibits it at higher value in CO2/N2/O2/NO/Hg0 system. The increasing concentration of NO with the stationary concentration of SO2 has a promotion to mercury adsorption while O2, NO, SO2 and Hg0 exists simultaneously. However, the increasing concentration of SO2 could enhance the mercury adsorption at initial stage and prevents it at the latter stage.
Abstract: Mercury concentrations in the flue gas at the stack were measured using a sorbent trap method as per United States Environmental Protection Agency Method 30B (i.e.,USEPA 40 CFR Part 60 30B),and the sampling method has merits of convenient setup, simply operation and fast analysis.Field tests were conducted at a unit of the Circulating Fluidized Bed Combustion (CFBC).During the course of sampling the mercury in the flue gas, coal samples, bottom ash and fly ash were collected and analyzed.Rates of mercury material balance though the unit were calculated, and correctness and validity of mercury sampling method were certified.Mercury distributions in fly ash, bottom ash and flue gas were evaluated, and the results showed that firstly bottom ash of CFBC removed only 0.55% of total mercury, secondly removal efficiency of fly ash reaching 83.37%, in the end 16.08% of total mercury was emitted to the air.The determined data of mercury emissions show that the CFBC is a clean coal combustion technology of effectively removing mercury.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
