Abstract: The influence of inorganic phosphorus on ash fusion characteristics of sewage sludge and coal were investigated by ash fusion temperature (AFT) detector and X-ray fluorescence (XRF), and the transformation of containing phosphate minerals of blended ashes with different temperatures between crystal and amorphous were explored using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). For the ash sample with high contents of Al2O3, which has higher AFT, raising content of phosphorus significantly results in a reduced ash fusion point, in particular it is lowered by 126℃ at 0-4% P2O5 content. But it has little effect on ash with high alkaline content. Aluminum phosphate (AlPO4) crystals is the major phosphor containing minerals in low temperature ashes, witch react with calcium minerals (CaSO4) and hematite (Fe2O3) to form Ca3(PO4)2 crystal and (Fe2O3)0.252(P2O5)0.748 glass phase along with increasing temperature. Meanwhile, (Fe2O3)0.252(P2O5)0.748 in glass phase increases with an increase in phosphorus content, which may be the primary cause of AFT decreasing.
Abstract: The reaction mechanism between arsenic and nitrous oxides (N2O, NO2 and NO) was investigated by applying density functional theory in quantum chemistry. The geometries of reactants, intermediates, transition states and products for each reaction were optimized. Frequency analysis was applied to verify those geometries, and the authenticity of transition states were confirmed by intrinsic reaction coordinate analysis (IRC). The stationary points of the single point energy were calculated at B2PLYP level, and the kinetic analysis was conducted to further reveal the reaction mechanism. Results show that the energy barrier of the reactions between arsenic and nitrous oxides (N2O, NO2 and NO) is 78.45, 2.58 and 155.85 kJ/mol, respectively. The reaction rate increases in the range of 298-1800 K and keeps at a high level (>1012 cm3/(mol·s)), although the temperature has a tiny impact on the reaction of arsenic with NO2 as a result of a low energy barrier, indicating that the reaction is easy to take place. Furthermore, it is found that the rate of reaction between arsenic and N2O or NO has a rapid increase at 298-900 K, and then the rate increment becomes less with the further increase of temperature.
Abstract: Influence of pyrite removal by chromous chloride (CrCl2) on structure of organic matter in Huadian oil shale was examined using ultimate analysis, 13C NMR, XPS and TG-MS technology. The results show that CrCl2 treatment leads to 96.19% removal of pyrite from oil shale. The relative contents of aliphatic, aromatic, and carboxyl/carbonyl carbons of organic matter remain about the same level after pyrite removal by CrCl2, so does the pyrolysis characteristic temperature, indicating the carbon skeleton of organic matter is less affected by CrCl2. However, the CrCl2 treatment can break C-O bond in organic matter and reduce content of C-O/C-OH and O=C-O, leading to about 0.98% and 12.54% loss for organic carbon and organic matter, respectively. In addition, carbon content of organic matter significantly increases, hydrogen content slightly increases, and oxygen content is markedly reduced after pyrite removal by CrCl2, resulting in a slight decrease of H/C but a marked decrease of O/C in organic matter. The mass loss of organic matter treated by CrCl2 increases during pyrolysis because aliphatic carbon content of unit mass of organic matter increases 5.28%. Besides, the residual chromium oxide may also promote decomposition of organic matter during pyrolysis.
Abstract: This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y, and lab-synthesised Fe-HZSM-5, Fe-H-Y, Pt/Al2O3 and CoMo/Al2O3). The experiments were all conducted in a semi-batch reactor under the same operating conditions for all feed materials. BET specific surface area, BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts, while gas chromatography-mass spectrometry (GC-MS), flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly seen that at higher catalyst-to-biomass ratios of 4:1, de-oxygenation efficiency did not experience any further significant improvement. Fe-HZSM-5 was deemed to be the most efficient of the catalysts utilised as it helped reach the lowest oxygen contents in the bio-oils samples and the second best was HZSM-5. It was also found that HZSM-5 and H-Y tended to privilege the decarbonylation route (production of CO), whilst their iron-modified counterparts favoured the decarboxylation one (production of CO2) for both biomasses studied. It was then seen that the major bio-oil components (carboxylic acids) underwent almost complete conversion under catalytic treatment to produce mostly unoxygenated aromatic compounds, phenols and gases like CO and CO2. Finally, phenols were seen to be the family most significantly formed from the actions of all catalysts.
Abstract: The spent residue hydrotreating catalysts were taken out from the different HDM bed axial position of a fixed-bed residue hydrotreating reactor of Petro-China. The coke on spent catalysts were studied by the technologies such as EA, TG, XPS, FT-IR and 13C NMR to get the structure characteristics and parameters. The results showed that the coke on spent residue hydrotreating catalysts located on different beds positions share some characteristics such as the kind of coke, the functional group, but the structure and composition were different from each other. Based on the result of each characterization technique, chemical structure models of coke were established. In order to ensure the accuracy of the structures, a software called gNMR helped to calculate the chemical shifts and predict the NMR spectra of the structure models. The model structures can be corrected to match the experimental results through comparing experimental spectra and the predicted ones.
Abstract: A series of supported [Bmim]3PW12O40/g-C3N4 catalysts (BPWO/g-C3N4) was prepared by coprecipitation, with 1-butyl-3-methylimidazole bromide, phosphotungstic acid and g-C3N4 as the raw materials. The morphology and structure of the BPWO/g-C3N4 catalysts were characterized by XRD, FT-IR, UV-vis, N2 physisorption, TEM and XPS; the effects of catalyst composition, oxygen to sulfur (O/S) ratio, catalyst amount and reaction temperature on the oxidative desulphurization efficiency were investigated by using n-heptane solution of dibenzothiophene (DBT) as a model oil and hydrogen peroxide as the oxidant. The results indicate that the BPWO/g-C3N4 catalysts have a Keggin-type heteropoly anionic structure and BPWO is well dispersed on g-C3N4. The BPWO(20%, mass ratio)/g-C3N4 catalyst exhibits the optimal oxidation performance towards DBT. Under 50℃ and with a O/S molar ratio of 6.0, DBT in the model oil with a concentration of 800 μg/g can be completely oxidized over the BPWO(20%, mass tatio)/g-C3N4 catalyst in 180 min. Moreover, the BPWO(20%, mass ratio)/g-C3N4 catalyst displays a good reusability and can be recycled for at least 8 cycles without any decrease in the DBT oxidation activity.
Abstract: A series of phosphotungstic acid (HPW) encapsulated metal-organic HPW@MIL-101(Cr) catalysts, with high surface area and high activity in the oxidative desulfurization (ODS), were synthesized by one-step hydrothermal method and characterized by FT-IR, XRD and nitrogen physisorption. The influences of synthesis time, temperature, HPW loading, and acidity/alkalinity on the catalytic performance of HPW@MIL-101(Cr) in ODS were then investigated. The results indicated that the order degree of channels in HPW@MIL-101(Cr) is improved with the increase of synthesis time and temperature. The crystal structure of MIL-101(Cr) cannot be formed at a synthetic temperature below 140℃ and the channel order of HPW@MIL-101(Cr) decreases under an acidic synthetic environment. The catalytic activity of HPW@MIL-101(Cr) displays a trend of first increasing and then decreasing with the increase of HPW loading. The HPW@MIL-101(Cr) catalyst with a HPW loading of 3.5 g, synthesized at 220℃ under neutral environment for 12 h, exhibits the highest activity in ODS. At 50℃, with a catalyst dosage of 0.24 g, an model oil of 20 mL, and an O/S molar ratio of 8, the desulfurization rates over the HPW@MIL-101(Cr) catalyst towards benzothiophene, dibenzothiophene, and 4, 6-dimethyl dibenzothiophene after reaction for 120 min reach 99%, 100% and 99%, respectively; in particular, the desulfurization rate for benzothiophene is 2.4 times higher than that obtained over HPW.
Abstract: The BiVO4/SBA-15 catalyst was prepared by post-hydrothermal method and characterized by XRD, SEM-EDS and N2 adsorption-desorption; its performance in the photocatalytic oxidation desulfurization was investigated in a homemade static desulfurization reactor. The results indicated that the BiVO4/SBA-15 catalyst presents mesoporous pore structure of SBA-15 molecular sieve and BiVO4 is evenly dispersed on the SBA-15 surface. The BiVO4/SBA-15 catalyst exhibits excellent activity in the photocatalytic oxidation desulfurization; for the desulfurization of a simulated diesel fuel over the BiVO4/SBA-15 catalyst with a BiVO4 loading of 15%, hydrothermally treated for 18 h and calcined at 530℃ for 3 h, the desulfurization rate reaches 95.6%.
Abstract: Dry reforming of methane (DRM) with CO2 is of great significance in the environmental protection and the utilization of natural gas. SiO2 and Al2O3 are two typical catalyst supports used in DRM. To elucidate the effect of these two supports on the catalytic performance, in this work, Ni/SiO2 and Ni/Al2O3 catalysts are prepared by the incipient wetness method and characterized by BET, TEM, H2-TPR, XRD, TG and Raman technologies. The results indicate that the performance of Ni-based catalyst is closely related to the properties of support and the Ni/SiO2 and Ni/Al2O3 catalysts are rather different in their DRM performance. Ni/SiO2 catalyst exhibits higher initial activity but poor stability; its catalytic activity decreases rapidly in 15 h for DRM at 800℃. Because of the weak metal-support interaction, Ni species on the Ni/SiO2 catalyst is present as large Ni particles, which may promote the formation of coke precursors, viz., the multi-carbon Cn species, leading to the fast carbonaceous deposition and catalyst deactivation. In contrast, the Ni/Al2O3 catalyst displays a lower activity but a much higher stability; its activity in DRM keeps stable in 50 h. Although Ni particles in the Ni/Al2O3 catalyst is much smaller, the strong metal-support interaction promotes the formation of NiAlxOy species during the catalyst preparation process, which may lead to a decrease in the content of active Ni species and give the Ni/Al2O3 catalyst a relatively low catalytic activity in DRM; however, the strong metal-support interaction between Ni and Al2O3 is also of benefit to the formation and stabilization of small Ni particles, which can alleviate the carbanceous deposition and afford the Ni/Al2O3 catalyst a better stability.
Abstract: A series of iron-molybdenum catalysts were prepared by controlling the acidity of ammonium molybdate solution in coprecipitation. The structure of the catalysts was characterized by N2 adsorption-desorption, Raman, XRD, SEM and H2-TPR. The Fe-Mo catalysts prepared with different pH values were investigated for their performance in methanol oxidation to formaldehyde reaction. The results showed that the acidity of ammonium molybdate solution affects the particle size, morphology, distribution and enrichment of iron and molybdenum species on the surface of the catalyst. Appropriate acidity of ammonium molybdate solution can optimize the ratio of MoO3 and Fe2(MoO4) species on the catalyst surface, and improves the catalytic oxidation performance, which is conducive to the improvement of yield and selectivity of formaldehyde.
Abstract: A series of RuO2-Fe2O3 catalysts varied in RuO2 loading were prepared by sol-gel method and used for selective catalytic oxidation of ammonia to nitrogen. The results indicated that all the RuO2-Fe2O3 catalysts showed an excellent low-temperature catalytic activity and the RuO2 loading played a key role in catalytic activity of ammonia oxidation. Moreover, the characterizations of BET, XRD, H2-TPR and DRIFTS were employed to investigate the relation between the physicochemical property of catalysts and catalytic activity. The research results elucidated that the introduction of RuO2 increased the surface area. The synergistic effect between RuO2 and Fe2O3 enhanced the redox property and the catalytic activity of ammonia oxidation. Meanwhile, the RuO2 loading gave the significant effect on surface acidity of catalysts. Lewis acid sites were predominant on the catalyst surface.
Abstract: A series of Mn-CeOx(LCS) catalysts with different molar ratios of metal nitrates to citric acid were prepared by low-temperature combustion synthesis (LCS) method. Through a comparison with the Mn-CeOx(CP) catalysts prepared by coprecipitation method (CP) as well as various characterization techniques such as XRD, XPS, FESEM, H2-TPR and nitrogen physisorption, the catalytic performance of Mn-CeOx(LCS) in the selective catalytic reduction (SCR) of NOx by NH3 was then investigated. The results show that the molar ratio of metal nitrate to citric acid is an important factor affecting the denitrification performance of the Mn-CeOx(LCS) catalysts. In comparison with the Mn-CeOx(CP) catalysts, the Mn-CeOx(LCS) catalysts are provided with a higher manganese content and high Oα/(Oα+Oβ) ratio on the surface as well as more hierarchical pores favorable for adsorption and reaction of reactants, which affords the Mn-CeOx(LCS) catalysts much better denitrification performance. Over the Mn-CeOx(LCS) catalyst with a molar ratio of metal nitrate to citric acid of 36:22, the denitrification rate at 80-180℃ reaches 75%-100%; even in the presence of SO2, the denitrification rate over the Mn-CeOx(LCS) catalyst at 180℃ keeps at the level of 74%.
Abstract: The effect of CO2 content(volume fraction 0-35%) on the reducing gas release characteristics from sewage sludge re-burning and the dynamic properties of NO reduction by sewage sludge and char were investigated in a simulated experimental platform of cement pre-calciner. The experimental results show that the reducing gas release from sewage sludge combustion are mainly HCN, NH3, CH4 and CO. With the increase of CO2 content from 0 to 25%, the release of HCN, NH3 and CH4 slowly decreased due to the enhancing effect of sludge gasification by CO2, while the release of CO increased significantly, eventually promoting the NO reduction rate from 51% to 61%. As continually increasing CO2 content to 35%, the local thermal instability was enhanced due to the radiation absorption of CO2, and the weakening of gasification resulted in the decrease of CO release. Moreover, HCN release decreased significantly, while NH3 release did not change much, CH4 release increased to a certain extent, and the combined effect makes the NO reduction rate gradually decreased to 55%. The results show that sludge re-burning can efficiently reduce NO in flue gas. It is also found that the homogeneous and heterogeneous reduction of NO are concurrence during sludge re-burning, while the experimental studies revealed that the NO reduction rate over the sludge char was only 18%, it implied that sludge denitration is dominated by gas-gas homogeneous reduction.
Abstract: Phloroglucinol-melamine-formaldehyde polymeric nanofibers (PMF) were hydrothermally synthesized by a polycondensation method using melamine, phloroglucinol and formaldehyde as starting materials. The effect of temperature on the PMF synthesis was investigated. The morphology and structure of the as-synthesized PMF were characterized by the scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption and Fourier-transform infrared spectrometer (FT-IR) etc. Pure gas adsorption equilibrium isotherms of CO2 and N2 were determined by the volumetric method. The PMF sample synthesized at 393 K presented a higher specific surface area (64 m2/g) and a higher adsorption capacity of CO2 (1.83 mmol/g@118 kPa, 298 K). Breakthrough column experiments indicated that efficient separation of CO2-N2 mixtures could be achieved on the PMF at 298 K and various pressures ranging from 200 to 600 kPa. After the PMF was thermally treated at 873 K in various atmospheres such as N2, H2, water vapor, etc., it was found that the specific surface area and micropore volume were greatly increased. Among the posttreated PMF samples, the one treated in 15% H2O stream showed an improved CO2 adsorption amount up to 2.83 mmol/g at 298 K and 118 kPa.
Abstract: The CuO-Ti3+/TiO2(Cu-TiMB) pholocatalyst was prepared by reducing TiO2 loaded with Cu-BTC (BTC, 1, 3, 5-benzoic acid) precursor; its photocatalytic performance in the removal of gaseous toluene was investigated. The result indicated that the toluene removal efficiency of CuO-Ti3+/TiO2(Cu-TiMB) by visible irradiation was 2.68 time higher than that of CuO-TiO2(Cu-TiD) prepared by impregnation. The CuO-Ti3+/TiO2(Cu-TiMB) catalyst shows relatively high surface area (147 m2/g), small particle size (0.45 μm), porous structure and high CuO dispersion; Ti3+ may provide a large number of oxygen vacancies, which can significantly enhance the photocatalytic response at 400-800 nm. In addition, Cu2+ and Cu+ may form heterogeneous structure with Ti3+, which can further increase the number of oxygen vacancies and delay the electron-hole pairs (e--h+) recombination time. The oxygen vacancies are effective in enhancing the ability for capturing adsorption oxygen, promoting the chemisorption ability by changing the valence state of metal oxides, and then improving the photocatalytic performance.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
