Abstract: Based upon isothermal methane adsorption on raw and solvent extracted coals, relationship between solvent polarity and methane adsorption capacity change of the coal was analyzed, and the possible geochemical mechanism was discussed from polarity of the solvents. The results show that methane isothermal adsorption curves on the extracted coals follow the Langmuir equation. Extraction with CS2 and C6H6 enhances methane adsorption capacities on extracted coals, and that with tetrahydrofuran (THF) and acetone is opposite. There is a negative correlation between methane adsorption capacity change of the coal and the solvent polarity, which can be explained by similarity-intermiscibility theory. The polarities of CS2 and C6H6 are weaker, which can extract more alkane and aromatic hydrocarbons with nonpolar molecule structure (-CH3 and -CH2-) to increase the adsorbed space of coal surface for methane adsorption. The polarities of THF and acetone are stronger, which can extract more non-hydrocarbon and asphaltene with polar molecule structure (-CHO, -OH and -COOH) to reduce the adsorbed space of coal surface for methane adsorption.
Abstract: Five oil shale kerogens from different regions were analyzed by KBr-FTIR spectra, and a quantitative determination method of structural parameters of kerogen aliphatic hydrocarbon was established by peak-fitting analysis. Thermogravimetric (TG) and Fourier transform infrared spectroscopy (FT-IR) analysis was used to online analyze devolatilization components of kerogen pyrolyzed at 20 ℃/min. The reactivity characteristic and variation of structural parameters of aliphatic hydrocarbon with pyrolysis time were obtained. The results show that the oil shale kerogen was composed of aliphatic hydrocarbon, aromatic hydrocarbon and oxygen functional groups. The relative content of aliphatic hydrocarbon structure, mainly long chain methylene, reaches 18.5%~78.2%. With increasing degree of kerogen evolution, the content of aliphatic hydrocarbon and capacity of oil generation decrease. The decomposition of kerogen mainly occurs during 350~520 ℃. The thermal weightless is mild when above 520 ℃ at which mass fraction of the residual char is 19.5%~52.2%. FT-IR analysis shows that free water releases out firstly during pyrolysis, subsequently depolymerization and dehydration reactions occur, and in which main side chains of alkane fall off and cyclization and oxygen-containing groups break into various of hydrocarbons, acids, alcohols, aldehydes, etc. until more stable graphite-like structure is formed.
Abstract: Mineral matters and carbonaceous structure of both raw and acid-washed Guangxi Heshan (GX) and Pingdingshan (PD) coals were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD). The FT-IR spectra demonstrate that the two raw coals are most abundant in kaolinite, followed by quartz and calcite. Some new mineral matters such as muscovite, serpentine, gypsum and alkali-feldspar are clearly observed from the second derivative FT-IR spectra. In addition, three OH stretching vibration peaks are shown in the FT-IR spectra at 3 695, 3 651 and 3 619 cm-1, indicating that the kaolinite in coals is not well crystallized. For demineralized coals, aromatic C=C peak (1 600 cm-1) and (002) diffraction peak of microcrystalline carbon are obviously shown in FT-IR and XRD spectra, respectively. In the case of raw coals, both FT-IR and XRD spectra show that the carbonaceous structure is almost completely inhibited by mineral matters. However, the defect carbon (D peak) and graphite carbon (G peak) are clearly found in the Raman spectra for both raw and acid-washed coals, since the mineral matters are completely inhibited by carbon due to more intensive signal. The crystalline carbon is found to be slightly less ordered for demineralized coals than for raw coals, and therefore the carbonaceous structure is slightly affected by acid treatment.
Abstract: The XRD and TGA were used to study the ash slagging and mineral conversion of Zhundong coal(ZDC) by adding different amounts of kaolin. The results show that the original minerals in Zhundong coal mainly include calcite, anhydrite and quartz, and merwinite and dicalciumsilicate are produced at high temperature. With the increase in the blending ratios of kaolin, the ash fusion temperature decreases at first, but increases later. After adding 3% kaolin into ZDC, gehlenite, fayalite, and merwinite are the main minerals produced at high temperature, which resulting in a low tempereture eutectic. When the blending ratio is above 6%, anorthite becomes the main mineral that have a high melting point, causing a great increase of ash fusion temperature to above 1 380 ℃. The slagging index calculation shows that the kaolin can relieve the slagging degree of ZDC obviously when the blending ratio is above 6%.
Abstract: Zhundong coal blending was combusted in a 350 MW boiler. Ash deposits samples at different heat transfer surface (HTS) were collected to investigate mineral conversion of each sample. Thermodynamic equilibrium calculation was carried out to give theoretical support by virtue of Factsage 5.2. Different mechanism of each HTS was concluded as follows. At high temperature HTS, albite, anorthite and other phases help eutectics precipitate take shape, which adheres to fly ash particles and forms indurate bulk ash deposits. At low temperature HTS, sulphur-containing species are condensed from flue gas to form deposits with evidence that the main crystalline phase is anhydrite. At economizer HTS, The deposits consisted of amorphous phases carried by flue gas are loosely bonded. Calculated results by Factsage basically agreed with the phase composition of actual samples and are of assistance to mineral conversion analyses.
Abstract: Ximeng lignite and cornstalk were used as the feedstock to prepare lignite char, biomass char and co-pyrolysis char with different blending ratios in a fixed bed reactor with temperature-programmed pyrolysis. The pore and chemical structure of char samples were characterized and the ash composition was analyzed. The oxidation reactivity of the mixtures of lignite char/cornstalk char with different blending ratios and the co-pyrolysis char of lignite and cornstalk with corresponding blending ratios were investigated by the isothermal thermogravimetry at 450 ℃, aimed at the effect of co-pyrolysis process on the char reactivity. The results show that there are obvious influences on the char structures through secondary reactions during co-pyrolysis process, leading to the char reactivity decrease. Especially with the cornstalk proportion less than 50%, these influences are more significant due to a large number of volatiles from cornstalk during co-pyrolysis enhancing the secondary reactions between the volatile and nascent char, prompting parts of organic structure less than 5 rings turn into the larger organic structure. For the char samples with cornstalk proportion above 50%, the catalytic effect of alkaline and alkaline earth metal in biomass char plays a dominating role, especially the effect of potassium, resulting in the weaker effects of secondary reactions on the structure and oxidation reactivity of the char samples.
Abstract: Aiming at the refractory characteristics of alkali lignin, the study on the gasification of alkali lignin in supercritical water was carried out in a batch reactor with Ru/C nanotubes as the catalyst. The effect of temperature, water density, time, concentration of the reactant, catalyst amount on the gasification of alkali lignin was discussed, as well as the catalytic efficiency of the Ru/C catalyst nanotubes. The optimum conditions of the catalytic gasification of alkali lignin on the Ru/C nanotubes obtained with single factor analysis were the reaction temperature of 600 ℃, 0.128 4 g/cm3 water density, 60 min reaction time, 3.0% reactant concentration, catalyst amount of 0.5 g/g (alkali lignin). The results show that during the gasification process of alkali lignin in supercritical water, the high temperature, high water density (or pressure), long reaction time, low reactant concentration and right amount of catalyst will be in favor of the gasification reaction. The alkali lignin gasification efficiency and carbon gasification efficiency reached 73.74% and 56.34% under the optimal reaction conditions, and the hydrogen production capacity was also significantly improved.
Abstract: The conversion of methanol to olefins (MTO), as a non-petroleum route to get valuable chemicals from multifarious carbon resources such as coal, natural gas and biomass, has attracted extensive attentions in recent years. The catalytic performance of acidic zeolites used in MTO is closely related to their framework structure and acidic properties; a clear understanding on this relation is of benefits to the development of better zeolite catalysts and improvement of current processes for MTO. Therefore, in this paper, we attempt to make a review on the recent research progresses in the effect of framework structure and acidity of zeolites on their catalytic performance in MTO. The review was focused on the difference of various zeolites in the hydrocarbon pool species, reaction pathway and catalytic kinetics; especially, the relation between the framework structure and acidic properties of zeolites and their catalytic performance in MTO was expatiated.
Abstract: The Y-Ni2P-T and Y-Ni2P-L were successfully prepared by temperature programmed reduction method (T) and low temperature hypophosphite method (L), respectively. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption specific surface area measurements (BET), CO uptake, and X-ray photoelectron spectroscopy (XPS). The effect of the rare earth yttrium (Y) on the HDS activity of catalysts prepared by different method was investigated using dibenzothiophene (DBT) as the model compound. The results show that for catalyst prepared by T method, the addition of Y can suppress the formation of the Ni5P4 phase and thus promote the formation of the active Ni2P phase. The addition of Y can dramatically increase the surface area and promote the formation of smaller and highly dispersed Ni2P particles. The DBT conversion of Y-Ni2P-T catalyst reached 91.0%, which is 29% higher than that of bulk Ni2P-T. For catalyst prepared by L method, the addition of Y can suppress the formation of the other impure phases. And the selectivity to BP over Y-Ni2P-T catalyst is improved, however, the total HDS activity of the catalyst decreases slightly compared with that of Ni2P-L.
Abstract: A series of Cu/Zn/Al/Si slurry catalysts were prepared by the complete liquid-phase technology with acid and alkaline silica sol in the paper. The catalysts are characterized by means of XRD, H2-TPR, FT-IR, BET, NH3-TPD, XPS and TEM. When the acid silica sol is added, which has the similar environment with the process of precursor preparation, the conversion of CO and selectivity of dimethyl ether reach maxiumum, being 65.38% and 76.26% respectively. The acid silica sol weakens the force between Cu and other components, resulting in the Cu component is easy to be reduced and more active lattice planes of Cu0 on the catalyst are exposed. The acid/alkaline properties of silica sol influence acid site strength and the number of acid sites of catalysts and make both strong acidic sites and the weak acidic sites migrate to lower temperature position. In DME synthesis reaction, it is found that the acid silica sol can increase the ratio of the weak acidic sites to the strong acidic sites on the catalysts, which promotes dehydration performance of methanol and the selectivity of DME. In addition, the catalysts with large specific surface area and mesoporous pore structure are favorable for the activity and selectivity of DME.
Abstract: Three Co/SiO2 catalysts doped with different amounts of Ru were prepared by incipient wetness impregnation. These catalysts were characterized by N2 physisorption, XRD, H2-TPD, DRIFTS, etc.; their catalytic performance in Fischer-Tropsch (F-T) synthesis was investigated in a micro fixed-bed reactor. The F-T reaction results showed that the Co/SiO2 catalysts doped with Ru exhibit higher CO conversion, higher turnover frequency (TOF), lower selectivity to CO2 and CH4, as well as lower ratio of olefin to paraffin, in comparison with undoped Co/SiO2. FT-IR spectra indicated that the Co-O bond in the as-prepared catalyst is weakened by the addition of Ru, which facilitates the reduction of the Co/SiO2 catalysts; such results are also supported by the H2-TPR profiles and XRD patterns of the reduced catalysts. The main cobalt phase in the reduced catalyst with 0.5% (by weight) of Ru is in a hexagonal close packing (hcp) structure. CO-DRIFTS results revealed that the peak of linearly adsorbed CO is red-shifted by the addition of Ru, suggesting an improvement on the dissociation of adsorbed CO. CO-TPD results showed that the ratio of COads/Cos and CO*/Cos on catalysts surface is increased by the addition of Ru, which may contribute to the decrease of the selectivity to CH4 in F-T synthesis.
Abstract: A series of Pt-S28O2-/ZrO2-Al2O3 catalysts were prepared by microemulsion method with pseudo-boehmite, γ-Al2O3, Al2O3 and Al(NO3)3·9H2O as aluminum source, respectively, and the resulting catalysts were characterized by XRD, FT-IR, BET, H2-TPR techniques. The influence of aluminum sources on the structure and acidic properties of the catalysts were investigated. The catalytic performance of the Pt-S28O2-/ZrO2-Al2O3 catalysts was studied using n-petane isomerization as a probe reaction. The results indicated that all the catalysts prepared with different source of aluminum can stabilize the tetrogonal ZrO2 phase and increase specific surface area of the catalysts. Except for pseudo-boehmite, the redox performance of catalysts prepared with other aluminum source were improved. The catalyst prepared with Al(NO3)3·9H2O as the aluminum source, which possessed the largest specific surface area and more superacid, exhibited the best isomerization performance. At a reaction temperature of 220 ℃, a pressure of 2.0 MPa, a hydrogen/hydrocarbon mol ratio of 4∶1 and a WHSV of 1.0 h-1, the isopentane yield reaches a maximum of 59.5%.
Abstract: The Cu2O/AC catalyst prepared by pyrolysis of copper acetate supported on activatede carbon was pretreated under oxidative (O2/N2) or reductive (H2/N2 and CO/N2) atmospheres. The oxidation/reduction of Cu2O was completed through pretreatment at 350 ℃ for 4 h, the Cu2O in catalyst could be completely oxidized to CuO by oxidative atmosphere, or reduced to metallic copper by reductive atmosphere. The catalyst activities were evaluated in a continuous fixed-bed tubular micro reactor under atmospheric pressure at 140 ℃. The catalyst pretreated by CO/N2 had good Cu0 dispersion on its surface and exhibited the highest activity. The space-time yield and selectivity of DMC reached 261.9 mg/(g·h) and 74.7%, respectively. After 58 h reaction, the valence state of copper species and the catalytic activity of catalysts pretreated by reductive atmosphere were found to be close to that of the Cu2O/AC catalyst. Comparing the catalytic performance, the characterization of surface and bulk copper species before and after reaction, it was obvious that metallic copper exhibited a high initial activity, while Cu2O was stable in catalytic activity and valence state, and CuO was low in activity.
Abstract: Urushibara nickel catalysts were prepared from aqueous NiCl2 solution with zinc powder as a reducing agent and used in phenol hydrogenation. The effects of zinc powder amount, reduction temperature and pretreatment-activation method on the catalytic performance of Urushibara nickel in phenol hydrogenation was investigated. To inhibit the magnetic agglomeration of the pure nickel catalyst, γ-Al2O3, CaCO3 and MgO were added as a support. The results indicated that the nickel catalysts obtained by zinc reduction can be pretreated and activated by NaOH or acetic acid solution, though the former is superior to the latter. The catalytic activity of Urushibara nickel is related to the amount of zinc used for the reduction. The nickel catalyst reduced at 100 ℃ with an n(Zn)/n(NiCl2·6H2O) ratio of 4.5 exhibits the highest hydrogenation activity. γ-Al2O3 as a support can promote the dispersion and sediment of the reduced nickel and alleviate the magnetic agglomeration. The Urushibara nickel catalysts are active for phenol hydrogenation at 120~160 ℃, with cyclohexanol and cyclohexanone as the main products; the conversion of phenol reaches 53%~66%, with the selectivity of 95.0%~96.0% to cyclohexanol.
Abstract: Aiming at the difficulty of elemental mercury (Hg0) removal from flue gas due to its indissolubility in water and the problem of lower SO2 resistance performance of manganese-based adsorbent, the MnOx-TiO2 adsorbents prepared with impregnation (IM), sol-gel (SG) and deposition-precipitation method (DP) were employed to remove Hg0 in the absence and presence of SO2. The adsorbents were characterized by N2 adsorption-desorption, TG-DSC, XRD, TEM, H2-TPR, and XPS techniques. The results showed that Hg0 removal performance over MnOx-TiO2 adsorbents was markedly influenced by the preparation methods. The adsorbent prepared by DP method exhibited a superior activity for Hg0 adsorption and the best SO2 resistance performance. The characterization results indicated that the Hg0 removal activity did not correlate with the BET surface area. The preparation method of deposition-precipitation could not only lead to an increase of reducibility and high dispersion of MnOx, but also significantly enhance a migration of well-dispersed active phase from bulk to surface, resulting in a higher Mn4+/Mn ratio and the presence of abundant chemisorbed oxygen, which would play an important role in promoting Hg0 removal.
Abstract: A CeO2-Fe2O3/TiO2 catalyst was prepared by impregnation method. The effect of CeO2 loading on the selective catalytic reduction of NO was studied. As a comparison, the catalyst in same optimum component proportion as above catalyst was also prepared by sol gel method. The BET, XRD, SEM and XPS were used for the catalyst characterization. The experimental results show that the catalyst of 10% CeO2 and 3% Fe2O3 by impregnation method has an optimal performance up to the reduction efficiency of 96.65%. The catalyst by sol gel method has better denitration performance than that by impregnation method, reaching 99.36% of efficiency. The characterization results show that all the 10%-3%CeO2-Fe2O3/TiO2 catalysts made by impregnation method or by sol gel method have the advantages of larger specific surface area, better dispersity of active ingredient, and better oxygen storage capacity.
Abstract: NO reduction by ethane over iron was experimentally investigated in a one-dimensional temperature- programmed ceramic tubular reactor at 300~1 100 ℃ in nitrogen and simulated flue gas atmospheres. The results show that ethane can effectively reduce NO to N2 over the surface of metallic iron. In N2 atmosphere, more than 95% of NO is reduced by ethane over metallic iron when the temperature is higher than 900 ℃. In simulated flue gas atmosphere, more than 90% of NO is reduced by ethane over metallic iron above 900 ℃ when the excess air ratio is lower than 1.0. Under the same conditions, NO reduction by ethane over iron is higher than that by methane. The effect of SO2 in simulated flue gas on NO reduction can be ignored. The iron samples were characterized with respect to their composition by XRD after reaction, and on this basis the reaction mechanism was further analyzed. There are two mechanisms for NO reduction, i.e., the reburning of ethane and direct reduction by iron. The iron is oxidized to iron oxides after reducing NO and then ethane reduces the iron oxides to metallic iron, leading to the sustainable and durable reduction of NO by iron. Meanwhile, NO is reduced by ethane through reburning to from the intermediate HCN that could be oxidized to N2 by iron oxide, furthermore the iron oxides are reduced to iron simultaneously. This process enhances the NO reduction and prevents the additional NO formation due to the oxidization of HCN during burnout, leading to a high NO reduction efficiency.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
