Abstract: Two coals were oxidized with aqueous NaOCl solution under mild conditions. The reaction mixture acidified was sequentially extracted with ethoxyethane, CS2, petroleum ether, acetic ester and benzene, followed esterification by CH2N2 and analysis with GC/MS. The results show that chloro-substituted compounds, aliphatic acids and aromatic polycarboxylic acids are main products. The oxidative product was sequentially extracted with different polar solvents and achieved a simple group separation. Effective separation and analysis of oxidation products of coal in aqueous NaOCl solution, established by the study, provides a feasible method for high value-added use of coal.
Abstract: Effect of alkali metal K on the hydrogasification of lignite was studied in a pressurized fixed-bed reactor, and the effects of temperature, pressure and catalyst loading on the reactivity of hydrogasification of lignite coal were examined. The experimental results show that the alkali metal K has a superior catalysis on the hydrogasification of lignite, and the carbon conversion of hydrogasification and the methane content in gaseous products can be up to 95% and 89%, respectively. The gasification reactivity can be enhanced obviously by increasing temperature, pressure and catalyst loading, and the catalyst loading saturation level is about 15%. The surface morphology and pore structure of coal samples with different catalyst loadings have been analyzed using scanning electron microscope (SEM) and gas adsorption/desorption analysis, which indicates that the specific surface areas and total pore volume decrease initially, and then increase with the increasing of catalyst loading.
Abstract: Experimental study on the slagging characteristics of Yulin & Pingshuo blended coals was carried out in a drop tube furnace. The slagging indexes were determined at different temperatures and the quantitative analysis on the composition of mineral matters in the ash slag was made using X-ray diffraction analysis (XRD). The results indicated that four crystalline minerals-iron oxide, anorthite, mullite, silica, and another amorphous glass are mainly consisted of the ash slag and the first three have a significant effect on the slagging tendency of coals. Higher content of iron oxide in the ash and anorthite in the ash slag, together with lower content of mullite in the ash slag leads to greater slagging tendency. According to this, using coal blending to obtain lower iron oxide content, and to decrease and increase the formation quantity of anorthite and mullite respectively, the slagging tendency of Shenmu type coal could be inhibited at a lower level.
Abstract: The CO2 gasification reactivity of coal chars blended with different proportions of coarse slag were investigated by using an STA449F3 thermo-balance in the isothermal mode at the temperature range from 900 ℃ to 1 380 ℃. The thermal behavior of the sample was studied using thermo-gravimetric analysis and differential scanning calorimetry (TG-DSC), and the two regions (i.e. the low temperature region and the high temperature region) for the gasification reactivity and carbon conversion of coal chars were defined according to the flow temperature of coal ash fusion. The gasification reactivity and carbon conversion of coal chars with coarse slag added are improved in the low temperature region. But the addition of coarse slag decreases the carbon conversion, and the gasification reactivity of coal chars blended with coarse slag to certain ratio also decreases in the high temperature region. It is indicated that the initial gasification reaction of coal chars is chemically controlled in the low temperature region, and diffusively controlled in the high temperature region.
Abstract: Hemicellulose can produce more acid content than cellulose and lignin via pyrolysis. This work reduced the hemicellulose and water content of pine via low temperature pretreatment to improve the bio-oil quality. The chemical composition and FT-IR analysis of pine after pretreatment show that the lignin content increases and the carbonization of pine takes place, which results in the decrease of bio-oil yield and the increase in yield of char and no-condensed gas. With increasing pretreatment temperature, the important characteristics of the bio-oil, such as water content, high heating value, kinematic viscosity, and density all increase, and solid particles content decreases, while pH value decreases after an initial increase. The 13C nuclear magnetic resonance (NMR) show that the aliphatic carbon of bio-oil decreases, while the aromatic and the aromaticity increases.
Abstract: Solid acid SO42-/ZrO2-CeO2 was prepared by co-precipitation impregnation method, which was used as catalyst for biodiesel production from Jatropha curcas L. fatty acids with methanol. Effects of CeO2 loading and calcination temperature on performance of the catalyst were examined; besides, single factor experiments and kinetics were also studied. The results show that SO42-/ZrO2-CeO2has higher catalytic activity. The conversion of fatty acids reaches 0.940 3 at 150 ℃ in 60 min when the weight ratio of catalyst to fatty acids is 8% and the volume ratio of methanol to acids is 2∶1. The kinetics calculation indicates that the apparent activation energy is 45.31 kJ/mol, and kinetic model is-dcA/dt=38371e-45310/RTcA1.44.
Abstract: Hydrolyzed polyacrylamide (HPAM) is a kind of polymer used for displacement of reservoir oil, while the oilfield sewage used to prepare HPAM may reduce its viscosity and impact the displacement efficiency. In this work, the HPAM solution was prepared according to the metal ions composition in Chengdong Oilfield sewage and the effect of metal ions on the viscosity of HPAM solution was investigated. It was found that the influencing extent of various metal ions on the viscosity of HPAM solution is in the order of Na+ > Fe2+ > Ca2+ > K+ > Mg2+. IR and SEM characterization results suggested that Na+, K+, Ca2+ and Mg2+ interact with the carboxylate anions, which may decrease the HPAM molecular charge density, make the polymer curl, reduce the solvation ability of polar groups, and release a large number of "bounded" water; these lead to the degradation of HPAM solution viscosity. On the other side, the viscosity degradation by Fe2+ is attributed to its interaction with oxygen in sewage, which initiates a free-radical reaction and causes the disintegration of the polymer chains.
Abstract: Niobium-promoted Fe/CNTs catalysts were prepared using a wet impregnation method. Samples were characterized by nitrogen adsorption, H2-TPR, TPD, XRD and TEM. The Fischer-Tropsch Synthesis (FTS) was carried out in a fixed-bed microreactor at 220 ℃, 1 atm and H2/CO=2 for 5 h. Addition of niobium into Fe/CNTs increased the dispersion, decreased the average size of iron oxide nanoparticles and the catalyst reducibility. Niobium-promoted Fe catalyst resulted in appreciable increase in the selectivity of C5+ hydrocarbons and suppressed methane formation. These effects were more pronounced for the 0.04%Nb/Fe/CNTs catalyst, compared to those observed from other niobium compositions. The 0.04%Nb/Fe/CNTs catalyst enhanced the C5+ hydrocarbons selectivity by a factor of 67.5% and reduced the methane selectivity by a factor of 59.2%.
Abstract: Co-Pt-ZrO2/γ-Al2O3 catalysts were prepared by using impregnation method and characterized by BET, XRD and TPR techniques; the effects of calcination and reduction temperature on their catalytic performance for Fischer-Tropsch synthesis (FTS) were investigated in a slurry-phase continuously stirred tank reactor (CSTR). The results showed that the catalysts calcined at high temperature exhibits low activity and selectivity to heavy hydrocarbons, since high temperature calcination may lead a strong interaction between cobalt species and γ-Al2O3 support, the formation of less reducible cobalt aluminate species, and aggregation of cobalt oxide crystals. Cobalt oxides cannot be reduced completely at a low temperature, while the aggregation or sintering of the active species may be prominent by carrying out the reduction at extra-high temperature; all these can deteriorate the catalytic performance of Co-Pt-ZrO2/γ-Al2O3. Under 483 K, 2.4 MPa, a H2/CO molar ratio of 2.0, and a space velocity of 3.6 L/(gcat·h), the catalyst 31.08%Co-0.11%Pt-7.16%ZrO2/Al2O3 calcined at 673 K and reduced in hydrogen at 653 K exhibits high catalytic performance for FTS; the conversion of CO and selectivity to C5+ reach 27.0% and 83.0%, respectively.
Abstract: The effects of Zn (100 gFe/x gZn, x=7～100) on the textural properties, reduction behavior and structural changes during reduction and reaction of the Fe-Zn catalysts were studied by using N2 physical adsorption, X-ray diffraction (XRD), Mssbauer spectroscopy (MES), H2 differential thermogravimetric analysis (H2-DTG) and CO temperature-programmed reduction (CO-TPR). The F-T performances of the catalysts were investigated in a fixed-bed reactor under the conditions of H2/CO=2.0, 260 ℃, 1.5 MPa and 4 000 mL/(g·h). The results show that, with the increase of Zn content in catalysts, the phases of catalysts transform from α-Fe2O3 and ZnFe2O4 to ZnFe2O4 and ZnO, where ZnO appears just beyond the stoichiometry of Zn/Fe (1∶2). The presence of ZnFe2O4 plays an important role in catalysts. In the fresh catalysts, ZnFe2O4 can enhance the dispersion of Fe phase and thus enlarge the surface area. For the reduced and used catalysts, ZnFe2O4 not only inhibits the excessive reduction and carbonization, but also improves the stability of the iron carbide phase. F-T tests show that the fast deactivation was observed in the un-promoted catalyst, but the catalytic activity was stabilized by ZnFe2O4 in Zn-promoted catalysts. In addition, high olefin selectivity is observed in Fe-Zn catalysts which gradually decreases to same content as that of un-promoted catalyst probably due to the change of phases at the beginning of reaction.
Abstract: Thermodynamics of poisoning on F-T synthesis catalyst with carbonyl sulfide were calculated according to some thermodynamic data and related software. Poisoning of Ru, Fe and Co can occur spontaneously under the conditions of F-T synthesis reaction because of the low negative value of ΔG thermodynamically. Ruthenium in Ru-based F-T synthesis catalyst can be poisoned by the COS on 10-9 level. There are many types of Fe and Co sulfide generated in the poisoning reactions. Their equilibrium constants are much different for different reactions, and their necessary concentrations of COS are also different. As the active phases of the Fe-based F-T synthesis catalyst are complex, it is feasible to develop some sulfur resistant catalysts. And for the Co catalyst, the characteristics of F-T synthesis reaction and the modification of catalysts may contribute to the development of sulfur tolerant catalyst possibly.
Abstract: Co3O4/CeO2 catalysts were prepared by co-precipitation-oxidation method and characterized by using X-ray diffraction (XRD), surface area (SBET) measurement and temperature-programmed reduction (TPR). The effect of cobalt content in Co3O4/CeO2 on its physical properties and catalytic performance in CO oxidation was investigated under both the humid and dry conditions. The results indicated that the Co3O4/CeO2 composite with a Co/Ce atomic ratio of 9 (calcined at 723 K) exhibits much smaller particle size and higher surface area than pure Co3O4; the addition of cerium to Co3O4 is beneficial to obtain Co3O4 with small particle size. The average particle size and BET surface area of Co3O4 in the Co3O4/CeO2 composite (Co/Ce atomic ratio=9) calcined at 538 K are 7.2 nm and 167.6 m2/g, respectively. Accordingly, the Co3O4/CeO2 composite exhibits excellent redox property.
Abstract: Ni-W-B and Co-W-B amorphous catalysts were prepared by chemical reduction. The resulting materials were characterized by BET, XRD and XPS, and the hydrodeoxygenation (HDO) performances of the catalysts were tested using 4-cresol as the model compound. The results showed that both of the two catalysts were amorphous structure. They showed high deoxygenation activity in the HDO of 4-cresol. However, in the HDO of 4-cresol at 523 K, Ni-W-B had high hydrogenation activity, showing 100.0% conversion of 4-cresol, 55.1% selectivity to 4-methylcyclohexanol and 44.1% of selectivity to deoxygenation. Co-W-B showed high activity of deoxygenation and the selectivity of deoxygenation was as high as 93.1%. It was mainly attributed to the different composition content of different elements with different valence states on the surface of the catalysts. Both of 4-cresol conversion and selectivity to deoxygenation could reach 100% over them at the conditions of 573 K and 4.0 MPa of hydrogen.
Abstract: Ni/ZrO2-SiO2 catalysts with 6% Ni loading amount were prepared by impregnation. The ZrO2-SiO2 support was also synthesized by impregnation. Effects of pH value of the impregnating solution and calcination temperature of support and catalyst on activities of Ni/ZrO2-SiO2 catalysts were investigated. The catalysts were characterized using XRD,TPR and SEM measurements. Ni/ZrO2-SiO2(S5) catalyst exhibited excellent catalytic activity with 100% of CO conversion, 1.8% of CO2 conversion and 16.6 (mmol·h-1·g-1) of CH4 formation rate. The preparation conditions were as follows:pH value of the impregnating solution, 8.0～9.0, calcination temperature of support and catalyst, 550 ℃ and 450 ℃.The mathanation activity of Ni/ZrO2-SiO2 was strongly influenced by the ZrO2 phase change. The catalyst with tetragonal zirconia showed higher catalytic activity. The increase of pH value of the impregnating solution was in favor of forming small tetragonal zirconia. The calcination temperature of support influenced the grain size and the dispersity of NiO, unsuitable temperature might lead to ill-fitted grain size and aggregation. Exorbitant calcination temperature could weaken interaction between NiO and the support, and lowered the dispersity of NiO.
Abstract: Volatile organic compounds (VOC) seriously affect the environment and human health. The removal of pollutants from coal-fired power plants based on ACF adsorption is a promising method. In this paper, hydrogen peroxide (H2O2) was used to modify the ACF sample, and the methods of N2 adsorption isotherm and XPS (X-ray photoelectron spectroscopy) were utilized to characterize the ACF samples. The adsorption tests of VOC (toluene as a typical representative) based on ACF were conducted and the effect of SO2 and NO on the adsorption of toluene were investigated. It was found that H2O2 modification had no impact on the BET surface and pore volume of the ACF sample, but increased the oxygen groups on the ACF surface. The results also indicated that SO2 or NO inhibited the adsorption of VOC on ACF, and this inhibition became strong with increasing concentration of SO2 or NO. It is also found that the coexistence of SO2 and NO deteriorated the adsorption VOC on ACF more seriously than the single existence of SO2 or NO.
Abstract: Manganese-substituted hexaaluminate catalysts (LaMnxAl12-xO19) were prepared by coprecipitation method. X-ray diffraction (XRD) characterization indicated that the LaMnxAl12-xO19 catalysts calcined at 1 200 ℃ has only hexaaluminate phase, while no inactive LaAlO3 or LaMnO3 perovskite phase, when the amount of manganese substituted (x) is 2.0～2.5. The UV-vsible diffuse reflection spectra, H2-TPR profiles and BET specific surface area measurements showed that Al sites substituted by Mn3+ are mainly the octahedral ones in hexaaluminate crystal at x ≥ 1.5. With the increase of the amount of manganese substituted, the Mn3+/Mn2+ ratio in the catalyst is increased and the specific surface area is decreased instead. O2-TPD profiles showed that the amount of lattice oxygen by chemisorption is increased and the amount of molecular oxygen by physisorption is decreased instead, with the increase of the value x. The catalytic tests for toluene combustion showed that the manganese-substituted hexaaluminate catalysts exhibits excellent low temperature activity and the preferable x value is 2.0～2.5. The catalytic combustion of toluene over LaMnxAl12-xO19 may follow the Mars-van Krevelen mechanism, in which Mn3+ and Mn2+ cooperate to promote the mobility of lattice oxygen.
Abstract: Modified activated carbon Fe-K/AC (activated carbon supported iron and potassium) was used as an oxidation catalyst for low concentration hydrogen sulfide (H2S) removed. The orthogonal design method was introduced in the research of Fe-K/AC preparation to determine the optimum condition and to measure the impact of different factors. Then, catalytic activity and mechanism on Fe-K/AC catalyst for oxidation of hydrogen sulfide was investigated. The optimum preparation condition of Fe-K/AC with high sulfur capacity and selectivity is that the iron and potassium content is 0.5% and 5.0%, respectively; and the calcination temperature and the Fe2+/Fe3+ atomic ratio is 600 ℃ and 0.5, respectively. The order of their influences is potassium content > iron content > calcination temperature > Fe2+/Fe3+ atomic ratio. Results from structural parameters and surface morphology of sorbents reveal that iron metal oxide loaded on the surface of activated carbon has the selective catalytic oxidation activity of hydrogen sulfide to element sulfur. Alkali metal oxide, which changes basic surface groups, has a synergistic effect on the catalytic oxidation of hydrogen sulfide. However,the catalytic activity decreases due to excessive metal oxides loadings that may block the accessibility of micropores and reduce the surface area.
Abstract: Simultaneous desulfurization and denitrification of flue gas by using urea/H2O2 solution were performed in a packed column. The results indicated that urea solution exhibits high removal efficiency towards SO2, but the efficiency of NOx removal is influenced by many factors such as H2O2 concentration, reaction temperature and initial pH value. Under the optimal conditions, the removal efficiencies towards SO2 and NOx reach 100% and 52.6%, respectively. Meanwhile, the reaction products were analyzed by chemical method and gas chromatography; the reaction mechanism and overall reaction equations for the simultaneous desulfurization and denitrification using urea/H2O2 solution are deduced. Current method may be used to modify the present wet desulfurization units and endue them with the ability of simultaneous denitrification.
Abstract: Titania-pillared clay (Ti-PILC) was obatined with two different Ti precursors of TiCl4 and Ti(OC3H7)4; with Ti-PILC as support, Mn-Ce/Ti-PILCs catalysts were prepared through impregnation. The catalytic activity of Mn-Ce/Ti-PILCs in low temperature SCR of NO with NH3 was investigated. XRD, BET, FT-IR, NH3-TPD and SEM measurements indicated that the pillaring process can change the structure of the clay; compared with the original clay, the specific surface area, the pore volume and the acidity of Ti-PILCs are increased; meanwhile, Mn-Ce/Ti-PILCs also exhibits higher catalytic activity than Mn-Ce/clay. Moreover, Ti(OC3H7)4 as Ti precursor is more effective in enhancing the catalytic activity of Mn-Ce/Ti-PILCs than TiCl4.
Abstract: Adsorption behaviors of four typical noble metals (Au, Pd, Pt, and Rh) on the CeO2(111) surface were systematically investigated by using density functional theory method. The results indicated that Au prefers to be adsorbed on the atop site, while Pd and Pt on the O-bridge site. Rh adsorbed on the 3-fold hollow site is the most stable configurations. When the noble metals are adsorbed on the atop site, the adsorption strength is in the order of Pt > Rh > Pd > Au. New electronic peaks are present between the Ce 4f and O 2p peaks when Pd, Pt, and Rh atoms are adsorbed on the CeO2(111) surface, while no peak is found for the adsorption of Au; the d electronic peak of Au overlaps with the O 2p peaks at-4 to-1 eV. According to the density of states (DOS) analysis, when Au is adsorbed on the atop site, Pd and Pt on the bridge site, and Rh on the 3-fold hollow site, their interactions with surface oxygen atoms on the CeO2(111) surface are stronger than other configurations, which is in good agreement with the results of Bader charge population.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
