Abstract: In order to describe pyrolysis characterization of Estonia oil shale kerogen, electron paramagnetic resonance (EPR) was carried out to analyze influence of pyrolysis temperature on free radical concentration, g factors and line width (△H) of Estonia kerogen and its pyrolysates. The results show that range of free radical concentration of Estonia oil shale and its pyrolysis oil, thermal bitumen and semi-coke is between 2.29×1014 and 9.16×1014. The free radical concentration and g factor of thermal bitumen is higher than that of semi-coke. The thermal depolymerization of kerogen mainly occurs before 380℃ and intermediate thermal bitumen mainly decomposes above 380℃. The line width of the samples shows that △H of shale oil is much higher than that of semi-coke and thermal bitumen at higher pyrolysis temperature. It means that the interaction between spin particles in free radicals and the interaction between the spin particles and environment in liquids are much more severe than solid samples. Below 380℃, △H of thermal bitumen and semi-coke increases with rising temperature. The interaction between the spin particles and environment was enhanced with pyrolysis proceeding. Above 380℃, △H of thermal bitumen and semi-coke decrease, indicating that the interaction between the spin particles is weaken with the rising temperature.
Abstract: According to the contradiction between ash melting theory and practice, an uneven melting theory was proposed. A typical Jincheng coal from Shanxi, China, was selected, which was ground into the particle size similar to the industrial use. It was separated into different density fractions through float and sink tests, and its chemical composition and mineral composition were analyzed with XRF and XRD, respectively. Ash fusion temperatures (AFTs) under light reducing atmosphere and the pressure-drop temperature(PDT) were tested. SEM-EDX was also employed to observe the melting behavior. It is found that the softening temperature of Jincheng coal is 1501℃, while that of its density fractions changes from 1292℃ to 1600℃. The sintering temperature changes from 833℃ to 943℃, while that of the raw coal ash was 885℃. The study of mechanism shows that the difference of melting and sintering behaviors is caused by the segregation of chemical composition in different density samples, mainly Al2O3, Fe2O3 and SO3.
Abstract: The n-heptane extraction residue (H-CT) from heavy medium and low temperature coal tar made in northern Shaanxi by n-heptane was reacted with formaldehyde. The product (P) was divided into n-heptane soluble (HS-P), n-heptane insoluble but toluene soluble (HI-TS-P), toluene insoluble but quinoline soluble (TI-QS-P) and quinoline insoluble (QI-P). The structure and composition of P were analyzed by means of GC-MS, TG-FTIR and FT-IR. The results show that P has more contents of TI-QS-P, oxygen atoms and a higher C/H atom ratio comparing with H-CT. The contents of HS-P, HI-TS-P, TI-QS-P and QI-P are 11.63%, 26.42%, 57.08% and 4.88%, respectively. HS-P and HI-TS-P contain mainly neutral components (mainly aromatics), few acidic components (mainly phenols), and some heteroatom compounds including O, N, S. TI-QS-P, with highly thermal stability, is rich in carbonyl groups, methylene bridge bonds and fused ring aromatic compounds. Besides, it also contains phenolic hydroxyl groups and aromatic ring substitutes.
Abstract: The release of alkali and alkaline earth metallic species (AAEMs) can cause serious technical problems during biomass thermal utilization. The release characteristics of AAEMs from rice straw char during pyrolysis in N2 and CO2 gasification at 900℃ were investigated using a fixed-bed reactor. The release and transformation results of AAEMs under both atmospheres were obtained based on analysis of solid residues sampled after different residence time, and effect of CO2 atmosphere on AAEMs migration was discussed. Under both pyrolysis and gasification conditions, K release ratio initially increased rapidly and the growth rate reduced with time. At early stage of gasification, K release ratio is higher than that after pyrolysis for the same time, while the K release ratio is almost same at late stage of gasification and pyrolysis. Little amounts of Ca and Mg were released during both pyrolysis and gasification. During pyrolysis, fractions of acid-soluble K and Ca first decreased and then remained nearly constant, while the fraction of acid-soluble Mg always remained constant. During gasification, the fraction of acid-soluble K first decreased slowly and then decreased rapidly, while that of Ca and Mg increased first and then reduced with time. At early stage of gasification, the fractions of acid-soluble AAEMs were higher than that after pyrolysis. At last stage of gasification, significant higher fractions of insoluble AAEMs were formed. CO2 atmosphere facilitated release of K by enhancing decomposition and release of char-K. Insoluble char-associated AAEMs are transformed to be acid-soluble due to consumption of char matrix. At the end of gasification, significant insoluble AAEM-silicates compounds were formed.
Abstract: Based on gasification of 4 N-rich biomass (SBS, RS, CS and MDF) in a horizontal tubular quartz reactor, formation characteristics of NOx precursors were investigated with the help of chemical absorption-spectrophotometry and XPS methods. Effects of fuel's properties (nitrogen functionality and nitrogen content) and gasification conditions (temperature and gasifying agent) were discussed and compared. The results indicate that NH3-N is the predominant NOx precursor species mainly produced during devolatilization stage. Each operational factor would alter the yield of each NOx precursor by affecting their formation pathways. On one hand, thermal stability of nitrogen functionality in fuels (N-A) is a much more important factor than nitrogen content among fuel's properties. Subsequently, due to the primary cracking of unstable N-A (polyamide), total yield of NOx precursors for MDF reaches up to 74.7% which is higher than that for other straw biomass by 15%. On the other hand, gasification conditions would influence the reaction routes relevant to NOx precursors during secondary reactions, especially for the hydrogenation reaction. As a consequence, during SBS gasification, when temperature rises from 800 to 1000℃, NH3-N yield keeps a constant increase from 38.9% to 47.7% while HCN-N increases first and then decreases with a peak value of 18.3%, which may depend on the balance between reaction routes affected by temperature. As for gasifying agent, the presence of CO2 would partly inhibit HCN-N yield while the introduction of H2O would moderately promote NH3-N yield, which is attributed that the hydrogenation reaction would be strongly affected by gasifying agent. Hence, it is concluded that the selectivity and partitioning of NOx precursors could be changed by employing different ratio of gasifying agents.
Abstract: The upgrading of the vacuum residue from Canadian oil sand bitumen was performed in a batch reactor with the syngas (CO/H2) and H2O. The effect of CO/H2-H2O for residue upgrading was verified. In the presence of CO/H2-H2O, the coke induction period is postponed by 3.5-6.5 min. When the coke yield is about 0.1%, the viscosity reduction efficiency can be raised by 29.1% at 410℃ and even 54.6% at 420℃. The upgrading experiments were also carried out in the presence of N2-H2O, CO-H2O, and H2-H2O, respectively. The results show that the capability to inhibit the coke formation was in the order of H2-H2O > CO/H2-H2O > CO-H2O > N2-H2O. The impetus of CO/H2-H2O to BVR upgrading could be attributed to the active hydrogen mainly from H2, nascent hydrogen by water-gas shift reaction as well as aqua-thermolysis. The thermal conditions such as the pressure of syngas, water content and reaction temperature could influence the coking propensity of BVR under CO/H2-H2O by affecting the three different attributions. These results indicate that the more accessible and low-cost syngas could provide the necessary hydrogen for BVR upgrading. Water presents a synergism with syngas for further promoting the BVR upgrading process.
Abstract: Ni/Al2O3 catalyst with various NiO loading was prepared with impregnation method. The catalytic performance for hydrogenation of 2-methylfuran to 2-methyltetrahydrofuran was investigated in this work. The results indicated that with an increase of NiO contents (10%, 20%, 25%, 30% and 40%), 2-methylfuran conversion rate first increased and then droped to a low level. The selectivity of this hydrogenation reaction showed the same trend. It was mainly because that NiO can produce more active center on catalyst surface, which was good for hydrogenation reaction. However, overloading of NiO blocked the mesopores of supportive Al2O3, and thus reduce the reaction selectivity and conversion rate. In batch reactor, after optimization the hydrogenation selectivity rate can be improved under hydrogen partial pressure of 3 MPa, reaction temperature of 150℃ and stirring speed of 1000 r/min. As a result, 2-methyltetrahydrofuran selectivity of 97.1% and 2-methylfuran conversion rate of 99.4% can be achieved with 25% NiO loading.
Abstract: NiMgAl-LDHs/γ-Al2O3 was first synthesized by in-situ co-precipitation method with γ-Al2O3 as support, which was further transformed to the NiMg(Al)O/γ-Al2O3 catalyst through calcination. The NiMg(Al)O/γ-Al2O3 catalyst was characterized by TG-DTG, XRD, SEM, N2 physisorption, FT-IR and CO2-TPD and its performance in the transesterification was investigated, for the production of biodiesel with microalgae oil and methanol as raw materials. The results show that NiMgAl-LDHs and NiMg(Al)O are successfully developed on the surface and pores of γ-Al2O3 with high binding strength. The NiMg(Al)O/γ-Al2O3 catalyst exhibits high activity in transesterification; with a methanol/oil molar ratio of 12:1, the yield of biodiesel oil reaches 95% after reaction for 3 h. Moreover, the yield of biodiesel is still above 82% after using seven times.
Abstract: ZrO2 was treated with 10% SO42- from different metal sulfate precursors for methanol dehydration to dimethyl ether. All the samples exhibited tetragonal phase and no diffraction peaks corresponding to metal sulfates or metal oxides were observed. The FT-IR results revealed that there were different interactions between sulfate and ZrO2, and this had a great effect on the surface area of the samples. The catalytic activity was measured over the catalysts in the temperature range of 100-300℃. The results revealed that sulfated zirconia with CuSO4·5H2O and Al2(SO4)3·16H2O showed the best catalytic activity. The maximum yield of DME ≈ 87% was obtained over CuSZ at a reaction temperature of 275℃. Moreover, the catalytic activity of the catalysts was correlated well with their surface acidity that measured by dehydration of isopropanol.
Abstract: Ni/SiO2 and Ni-based bimetallic Ni30M/SiO2 catalysts (with a Ni/M atomic ratio of 30; M=Fe, Co, Cu, Zn and Ga) were prepared by the impregnation method and characterized by the means of H2-TPR, XRD, H2 chemisorption, NH3-TPD and N2 sorption; the effect of M promoters on the structure and performance Ni-based catalysts in the hydrodeoxygenation of anisole was investigated. The results indicated that the metallic promoters have a significant influence on the reducibility of nickel species, due to the interaction between M and Ni species, although the sizes of Ni-M bimetallic crystallites in Ni30M/SiO2 are similar to that of Ni crystallite in Ni/SiO2. Because of the interaction between Ni and M and the enrichment of certain M promoters on the surface of Ni-M bimetallic particles, the adsorption quantity of H2 on Ni30M/SiO2 is lower than that on Ni/SiO2. In addition, the Ni30M/SiO2 catalysts also have more acid sites (especially the weak ones) than Ni/SiO2. For the hydrodeoxygenation of anisole under 300℃, 0.1 MPa, weight hourly space velocity (WHSV) of anisole of 1.0 h-1 and H2/anisole molar ratio of 25, the Ni30M/SiO2 catalysts exhibit lower anisole conversion than Ni/SiO2, probably due to the lower H2 uptakes on the bimetallic catalysts. However, Ni30Ga/SiO2 and Ni30Zn/SiO2 give much higher selectivities to BTX (benzene, toluene and xylene) (81.7% and 76.8%, respectively) than Ni/SiO2 (71.5%). Meanwhile, Ni30Zn/SiO2 exhibits higher activity in methyl transfer and lower activity in C-C bond hydrogenolysis than other catalysts; owing to the high oxophilicity of Zn, from the aspects of increasing carbon yield and reducing H2 consumption, Ni30Zn/SiO2 is probably an appropriate catalyst in hydrodeoxygenation.
Abstract: Effects of calcination temperature and calcination time on the crystal structure, reduction characteristics, pore structure and CO methanation performance of Ni-Al2O3 catalyst were investigated by using a mechanical-chemical method to prepare Ni-Al2O3 catalyst. The catalysts were characterized by XRD, H2-TPR, BET, XPS and TPH. The results showed that the calcination temperature increased from 350℃ to 700℃, NiO was still well dispersed on the surface of the carrier, and the reduction peak temperature decreased to high temperature. The specific surface area of the cat-450 sample obtained by calcination at 450℃ was 350 m2/g. The results showed that with the calcination temperature increased from 350℃ to 700℃, CO conversion, CH4 selectivity and yield were increased first and then decreased, reaching the maximum at 450℃, with 97.8%, 88.2% and 86.2%, respectively. In addition, the calcination time has little effect on the reduction performance of the catalyst, and has small influence on the crystal structure of the carrier Al2O3. With the increase of calcination time, CO conversion decreased slightly and then increased with the better calcination time of 4 h.
Abstract: In order to study the influence of reactant concentration on the formation of ammonium bisulfate and ammonium sulfate, a simulating flue gas system with a more accurate composition of SO3 was established. The starting temperature of ammonium bisulfate is about 230-270℃ and the peak temperature is about 180-240℃ under the experimental condition. The starting temperature and peak temperature of ammonium sulfate are about 40℃ lower than that of ammonium bisulfate. The formation of ammonium bisulfate is obviously higher than that of ammonium sulfate. With different concentration and molar ratio of NH3 and SO3, the formation rate of ammonium bisulfate is about 64%-90%, about 6-10 times of that of ammonium sulfate with about 6%-15% at 120℃. The increase of reactant concentration can promote the formation of both ammonium bisulfate and ammonium sulfate. And SO3 is more conducive to the formation of ammonium bisulfate than NH3. Further analysis shows that the variation curve of the generation fraction of ammonium bisulfate and ammonium sulfate with temperature presents a single peak. As the reactant concentration increases, the temperature range at which the peak is located increases gradually.
Abstract: A series of monolithic cordierite-based Ce-Fe/Al2O3 catalysts were prepared by sol-gel and impregnation method. The selective catalytic reduction of NO with C3H8 over the catalysts were experimentally studied. Results indicated that when the addition of cerium increased from 1% to 5%, the C3H8-SCR of Ce-Fe/Al2O3/cordierite increased at first then decreased and 3.5Ce-Fe/Al2O3/cordierite showed the highest C3H8-SCR activity with 96.5% NO reduction in the presence of oxygen at 600℃. Cerium was able to improve the resistance to SO2 in the flue gas for the Fe/Al2O3/cordierite catalysts. When 0.02% SO2 was fed into the flue gas during the test, the NO reduction by 3.5Ce-Fe/Al2O3/cordierite with C3H8 was always kept at about 93%, while the NO reduction by the catalyst without Ce, i.e., Fe/Al2O3/cordierite, decreased from 88% to 80%. The catalysts were characterized using XRD, N2 adsorption-desorption, SEM, H2-TPR and Py-FTIR spectra of adsorbed pyridine. Results showed that the addition of cerium to iron oxide could form the solid solution, which could increase the Lewis acid concentration and redox property of the catalyst, thus improving the performance of catalytic reduction of NO with C3H8. However, the introduction of too much cerium would reduce the crystallinity of iron oxide nanorods, then inhibited the formation of the NO2/NO3- species in the C3H8-SCR reaction, resulting in a decrease in the efficiency of NO reduction.
Abstract: Nitrogen-doped mesoporous carbon (NMCs) with high N doping level and developed mesoporous structure were prepared by a nanoscale-size SiO2 template-assisted blend carbonization process, using anthracene oil (AO), one of distillates of coal tar, as carbon source and melamine (M) as nitrogen source. With the assistance of elemental analysis, FESEM/TEM, N2 adsorption-desorption and XPS characterizations, the effects of various synthesis parameters on the chemical composition, pore structure and the catalytic performance of NMCs in H2S oxidation at room temperature were investigated. The results show that NMC sample with suitable nitrogen doping level, abundant pyridinic/pyrrolic configurations, uniform large mesopore size, as well as high pore volume and specific surface area can be prepared by using appropriate amount of template agent, carbon/nitrogen source ratio and carbonization temperature (700℃), which exhibits high efficiency in the removal of H2S through catalytic oxidation at room temperature.
Abstract: Biochar nano-sheets (BXG-AC) with high surface area and porous structure were prepared by direct pyrolysis of the inner membrane of passion fruit and subsequent KOH activation. The morphology and surface elemental composition of BXG-AC were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and the electrochemical behaviors were investigated by cyclic voltammetry and linear sweep voltammograms (LSV). The results indicate that in neutral media, the as-prepared BXG-AC catalyst exhibits remarkable electrocatalytical activity; a maximum power density of 1153.3 mW/m2 is achieved in the microbial fuel cells (MFCs), which is comparable to that of commercial Pt/C (1214.3 mW/m2). Furthermore, the BXG-AC cathode also displays a great long-term stability; the MFC output decreases slightly after operation for more than 60 cycles. This study demonstrates that the biochar nano-sheets derived from the inner membrane of passion fruit is probably a cost-efficient and promising cathodic catalyst for the scale-up MFCs.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
