Abstract: The standard curve method established by predecessors to measure the concentration of free radicals in coal was optimized to take the quadratic integral area ratio of the DPPH standard sample to the reference sample as new parameters. The results show that the relative error between the measured and theoretical values of the new parameter standard curve method is less than 5%, and the relative standard deviations of repeatability and reproducibility are less than 3%. The new parameter standard curve method was used to analyze the free radical concentration of the coal with different coal ranks and the asphaltene of Xinjiang Heishan Coal (HS). It is found that with the increase of coal rank, the free radical concentration in the coal increases gradually, from 8.531×1017/g for low-rank lignite to 3.37899×1019/g for high-rank anthracite. In the process of HS coal liquefaction, with the increase of liquefaction temperature, the free radical concentration of asphaltene decreases gradually, from 1.5793×1018/g at 290℃ to 7.410×1017/g at 450℃. The change trend of free radical is concentration in the asphaltene consistent with that of asphaltene yield.
Abstract: XRD and Raman spectroscopy were used to study chemical structure evolution of Shenmu coal in the main pyrolysis temperature range (450-750℃) and three pyrolysis atmospheres (N2, H2-containing and CO-containing). Correlation of structural parameters obtained by the two methods was compared. The results show that the char prepared by pyrolysis of raw coal in N2 has a continuous increase in the size of carbon crystallites in the transverse direction, a gradual increase of spacing in the longitudinal direction, and a sharp change of stacking height around 650℃. Raman parameter AD1/AG increases, while AG/Aall decreases, indicating a decrease in proportion of the ordered char structure. The H2-containing atmosphere promotes the longitudinal development of the carbon crystallite structure, increases the conversion of small molecule groups and the ordered degree of char. The influence of CO-containing atmosphere on the carbon crystallite structure parameters is less than that of the H2 atmosphere. But below 700℃, the dense carbon particles produced by CO-containing atmosphere due to carbon deposition are entrapped on the char surface, resulting in an increase in the ordered degree of char carbon. There is a certain correlation between Lc and AG/Aall, and d002 and AD1/AG of char; La has a good positive correlation with AD1/AG.
Abstract: The shape selection features of molecular sieve were used to efficiently separate the mixed phenols of oil fraction from coal direct liquefaction. In this paper, m-cresol and p-cresol were selected as the model compounds for coal liquified oil fraction. The pore structure of HZSM-5 adsorbent was adjusted by chemical liquid phase deposition method. Influence of ratio of silica to alumina and particle size of molecular sieve on the structural properties after modification were investigated. Considering the modified effect on adsorption and separation properties of cresol and p-cresol, a high-performance solid phase adsorbent was obtained, and was applied to separation of phenols in liquid oil from 180-190℃ fraction. The results show that when the molecular sieve has a silica-alumina ratio of 25 and a particle size of 3-5 μm, the pore structure adjustment effect of the molecular sieve is optimal. When the minimum amount of tetraethyl orthosilicate is 0.2 mL/g, the adsorption capacity of solid phase adsorption is 0.03 g/g, and the selectivity of p-cresol is greater than 95%. The selectivity to p-cresol is increased due to changes in the orifice regulation of the adsorbent on the outer surface deposits. Furthermore, using modified HZSM-5(1) adsorbent to separate the mixed phenols from real coal direct liquefied oil, the selectivity of phenol and p-cresol reached 100%.
Abstract: Effective separation of phenols in coal tar is essential for enhancing its application value. In this work, polyvinylpyrrolidone (PVP) was used as a sorbent in the separation of phenols in model oils; the adsorption performance of PVP towards o-cresol, m-cresol, p-cresol, 1-naphthol, and 2-naphthol was then comparatively investigated. The results indicate that PVP possesses high adsorption capacity towards the phenols; the maximum adsorbance of PVP towards m-cresol, p-cresol, 1-naphthol, and 2-naphthol is higher than 1000 mg/g. For the adsorption of phenols on PVP, H-bonds are formed between the Lewis basic sites (C=O and N) of PVP and the phenolic -OH group and the H-bonding intensity is influenced by the steric hindrance of phenols. Furthermore, PVP shows high adsorption selectivity; 2-naphthol can be adsorbed effectively on PVP even in the presence of benzofuran or quinoline. Moreover, PVP can be regenerated for recycling where phenols are recovered as well. As a result, PVP is a promising sorbent for the separation of phenols from the coal tar oil.
Abstract: A series of Ni based catalysts are prepared through impregnation method with coconut shell, bamboo charcoal and charcoal activated carbons as the support; their catalytic performance in the pyrolysis of waste plastics to produce carbon nanotubes was comparatively investigated. The structure and morphology of the catalyst and carbon nanotubes were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectroscopy, thermogravimetric analysis and nitrogen physisorption. The results show that carbon nanotubes with the highest yield and the best quality can be produced by using the nickel catalyst supported on coconut shell activated carbon (Ni/CSAC). In addition, the effect of reaction temperature and nickel loading on the catalytic performance of Ni/CSAC in the pyrolysis of waste plastics was considered.
Abstract: Four nano-Fe3O4 catalysts with different particle sizes were prepared by high temperature pyrolysis and low temperature two-phase reflux method; their performance in the hydrothermal cracking and viscosity reduction of Liaohe oil-field heavy oil was investigated. The results indicate that the addition of sodium sulfonate (HABS) surfactant in the preparation process can effectively improve the dispersion of Fe3O4 catalyst in heavy oil for hydrothermal cracking; the HABS-modified 9 nm Fe3O4 catalyst prepared by high temperature pyrolysis exhibits the best viscosity reduction performance. In a reaction system with 250 g heavy oil and 0.75 g n-hexane as hydrogen donor, where the mass ratio of heavy oil:catalyst:reservoir water is 100:0.3:30, the viscosity of heavy oil can be reduced from 86200 to 2065 mPa·s after reaction at 240℃ for 24 h; the viscosity reduction rate is as high as 97.6%. Analysis on the reaction mechanism suggests that the nano-Fe3O4 catalyst attacks the C-S bond on the long-chain heavy oil, breaks the bond and converts the heavy component into light component.
Abstract: The heavy fraction of Hami pyrolysis tar was firstly hydrocracked in a suspended bed reactor, and the as-prepared light product oil was analyzed. The light oil that retains the basic unit structure characteristics of coal and contains a large number of naphthenes and aromatic compounds as well as high nitrogen content was then used to produce naphtha in a 200 mL fixed bed refining-cracking tandem unit. The effect of different temperatures on the hydrocracking reaction was investigated at reaction pressure of 15 MPa. The results show that the optimum cracking temperature is 390℃, at which the conversion of >180℃ fraction is 53.69%, the hydrogen consumption is 5.13%, and the < 180℃ naphtha yield reaches 56.8%. The main components of naphtha are C6-9 hydrocarbons with the naphtha of 71.99%, the naphthene of 3.13% aromatics and the aromatic potential of 70.1. The catalytic reforming of cracked naphtha under optimum conditions to produce BTXE was conducted and compared with that with the middle base naphtha of petroleum series as feed. After reforming, the yield of BTXE from cracking naphtha is 55.85%, 25.53% higher than that from petroleum-based naphtha. The advantages and characteristics of coal-based oil are highlighted. It is verified that naphtha from coal pyrolysis heavy oil hydrocracking is a good raw material for preparing BTXE.
Abstract: A series of phase transfer catalysts, composed of vanadium-substituted phosphotungstic acid(H4[PW11VO40]) and different quaternary cationics were synthesized through ion exchange method. The characterization of FT-IR spectroscopy and X-ray diffraction confirmed that the integrity of polyoxometalate anions and quaternary ammonium cations immobilized in the phase transfer catalyst. The as-prepared catalysts were applied to the catalytic oxidative desulfurization of model diesel oil using H2O2 as oxidant. The influencing factors such as quaternary cationics species, catalyst composition, catalyst amount, oxygen-sulfur ratio and reaction temperature were investigated.[(C16H33(CH3)3)N]3H[PW11VO40] is found to be efficient and reusable catalyst for oxidative desulfurization reaction. Under the optimized reaction conditions of n(catalyst)/n(model diesel)=1:80, n(H2O2)/n(model diesel)=8:1, 50℃, 3 h, the catalyst exhibits the dibenzothiophene conversion of 100% and excellent reusability with 99.7% conversion after five times reaction. The catalyst and reactants form a microemulsion system and behave like homogeneous mixture during reaction, but precipitates with biphase separation when the reaction ends. The catalyst could be quickly separated and recycled by centrifugation.
Abstract: Attapulgite (ATP) and ATP mixed with SiO2 microspheres (ATPS) supported Cu-Fe-Co modified Fischer-Tropsch (F-T) catalysts were prepared by impregnation method (IM) and impregnation-solution combustion method (IMSC). The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR) and CO2-temperature programmed desorption (CO2-TPD). The catalysts were also applied to lower alcohols synthesis from CO hydrogenation. Results show that the IMSC method is much beneficial for the loading, dispersion and reduction of CuO on the prepared catalyst than IM method, which promots the touch of H2 and CO with Cu active site. The optimum reaction temperature for lower alcohols synthesis is 280℃ for the catalysts prepared by both methods. Through the optimization of catalyst combination system between ATP and ATPS supported Cu-Fe-Co based catalysts (CFCK/ATP, CFCK/ATPS) and Cu/ZnO/Al2O3 catalyst (CZA) for methanol synthesis, the ideal catalyst combination system, CZA‖CFCK/ATPS-IMSC, is obtained for lower alcohols synthesis. For the dual-bed configuration, a lower alcohols selectivity of 39.6% with the fraction of C2+ alcohols of 22.7% in oxygenates is achieved at CO conversion of 46.3% via the product conversion coupling effect.
Abstract: A new scheme for constructing composite catalyst composed of oxide-modified bimetallic nanoparticles was proposed, where perovskite-type oxide (PTO) is utilized to confine multifold metal ions in the perovskite crystal lattice. With a perovskite-type oxide (PTO) of La1-yCeyCo0.87Pt0.13O3 loaded on large surface area SiO2 as the precursor, where the La, Ce, Co and Pt ions were uniformly mixed and confined in the PTO crystallites, a series of Pt-Co/La-Ce-O/SiO2 catalysts were prepared through reduction. The Pt-Co/La-Ce-O/SiO2 catalysts were characterized by nitrogen physisorption, XRD, H2-TPR and TEM; their catalytic performance in CO oxidation was investigated. The results indicate that La-Ce-O-Pt-Co clusters are constructed on the SiO2 surface, forming platinum-cobalt nano-bimetallic particles after reduction; the modification of Pt with Co can enhance the catalytic activity and the addition of Ce can further improve the catalytic performance in CO oxidation. The La0.8Ce0.2Co0.87Pt0.13O3/SiO2 catalyst with y=0.2 (representing the Ce content) exhibits high activity in CO oxidation; over it, a complete conversion of CO can be achieved at 120℃. The La0.8Ce0.2Co0.87Pt0.13O3/SiO2 catalyst performs well for CO oxidation even in the presence of 15% (volume ratio) H2O and 12.5% (volume ratio) CO2. Moreover, the oxide-modified platinum-cobalt nano-bimetallic catalysts display excellent stability with high resistance against sintering.
Abstract: Silver has been widely used to modify the iron-based catalyst supported on alumina pillared montmorillonite to enhance its activity at lower temperature (< 300℃). Bimetallic Ag-Fe/Al-PILC (Pillared interlayer clay) was prepared by the ultrasonic impregnation method and performance was tested on a fixed bed reactor. And the experiment results showed that silver obviously improved the catalyst activity at a lower temperature. The NO conversion efficiency of Ag-Fe/Al-PILC at 250℃ was 60%, which was higher than Fe/Al-PILC (20%). The maximum 82% NO conversion and 100% N2 selectivity were obtained by 2.1Ag-Fe/Al-PILC at 250℃. Moreover, Ag-Fe/Al-PILC revealed better anti-hydrogen peroxide and anti-sulfur dioxide ability. The catalyst characterization was conducted by several techniques with respect to the microstructure and physicochemical properties. According to the effects of N2-adsorption and desorption tests, Ag-Fe/Al-PILC formed a stable overall structure and had a large internal specific surface area. Besides, XRD and UV-vis proved that the Ag-Fe solid solution, Ag+ and Agnδ+ species formed on the surface of the catalyst are the key factors affecting its low-temperature activity. XPS results suggested that there was electron transfer between Ag and Fe, which formed a synergistic effect of bimetals and changed the content of Ag and Fe and their valence state on the catalyst surface. The findings of H2-TPR indicated that the modification of Ag promoted the shift of the Fe/Al-PILC reduction peak toward low temperature, which boosted the low-temperature reduction capacity of the catalyst. The surface acidity analysis by Py-FTIR indicated that Lewis acid and Brønsted acid existed simultaneously and Ag enhanced the stability of Brønsted acid.
Abstract: A series of Ag-Mn/γ-Al2O3-TiO2 catalysts were prepared by different impregnation procedures. The catalysts were characterized by BET, XRD, TEM, XPS and H2-TPR, and the catalytic properties were investigated by propane catalytic combustion. Results show that compared with the conventional impregnation method, complexation-impregnation procedure with citric acid promotes the dispersion of Ag and Mn particles on the surface of catalyst and strengthens the interaction between Ag and Mn, so as to increase the relative content of reactive oxygen species and improve the reducibility of catalysts, which further improves the catalytic activity of propane combustion reaction. Especially, the Ag1Mn3/γ-Al2O3-TiO2 catalyst prepared by complexation-impregnation process with citric acid exhibits the best activity for propane catalytic combustion with 90% conversion at 263℃.
Abstract: A series of CeO2-ZrO2 solid solutions with different Ce/Zr molar ratios were synthesized by one-pot evaporation-induced self-assembly (EISA) method and characterized by XRD, Raman spectroscopy, H2-TPR, XPS, SEM and N2 sorption. The catalytic activity of CeO2-ZrO2 solid solutions in the thermochemical splitting of CO2 to CO were investigated by thermogravimetric analysis. The results reveal that with the increase of Ce/Zr molar ratio, the catalytic activity of CeO2-ZrO2 in CO2 splitting increases first and then decreases. The Ce0.5Zr0.5O2 solution with a Ce/Zr molar ratio of 1 exhibits high activity in CO2 splitting, owing to its abundant lattice defects and oxygen vacancies which can promote the oxygen migration. In contrast, the Ce0.75Zr0.25O2 solution with a Ce/Zr molar ratio of 3 shows the best cyclic stability, due to its relatively stable number of oxygen vacancies. Sintering of particles was observed after the cycling reaction, accompanying with the phase separation in the Zr-rich solid solutions, which may influence the catalytic performance of CeO2-ZrO2 solid solutions in the CO2 splitting.
Abstract: Combined with the superior resistance to sulfur as well to water of antimony, and the ability of tungsten to increase the activity of vanadium-based catalysts, antimony and tungsten were used as promoters to prepare the V-W-Sb/Ti catalysts using impregnation method, and the denitrification of the modified catalysts made by different preparation conditions was investigated. The tests of the activity and the resistance to H2O and SO2 were carried out in a fixed bed reactor, and the catalysts were characterized by N2 physical adsorption-desorption, X-ray diffraction, NH3-TPD test and H2-TPR. In the case of the selected catalyst formulation 3V2O5-5WO3-2Sb2O3/90TiO2, the experimental results show that the catalyst prepared by using antimony acetate as the precursor has better activity than that prepared by using antimony chloride as precursor; the catalyst prepared by calcination at 400℃ has higher denitrification efficiency than that prepared at 500℃; the difference in the number of impregnation steps has a limited effect on the activity of the catalyst. At the denitrification temperature of 180℃, and 10% (volume ratio) H2O and 0.01%SO2 added in the feed gas, under the same calcination temperature, the activity of the catalyst prepared by two-step impregnation and using antimony acetate as the precursor is only 2% higher than the catalyst prepared by one-step impregnation and using antimony chloride as the precursor, the latter one has a simple and convenient preparation process, so it has more industrial application value.
Abstract: To realize innocent treatment of oil sludge char, a lab-scale fluidized bed reactor was employed to study combustion of the oil sludge char in the term of nitrogen oxide emission characteristics at various different temperatures and particle sizes, as well as the reduction in the emission of NOx by using air-staging combustion technology. According to the results of scanning electron microscope and physical adsorption analyses of oil sludge char, the surface structure of the sludge char is dense and its pores are sparse, which is not conducive to the full combustion of organic matter inside. The combustion experiments of oil sludge char show that the generated NOx is mainly from coke-N and less from volatile-N. Reduction in the combustion temperature and the particle size to a proper extent can not only ensure full combustion of oil sludge char, but also inhibit NOx emission. When conducting air-staging combustion, by optimizing the excess air ratio, proportion of secondary air and position of secondary air inlet, the NOx emission is considerably reduced, and meanwhile the generation of fly ash is restrained, and these are beneficial for the ultimate treatment of the flue gas.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
