Abstract: Based on proximate and ultimate analysis, 13C CP/MAS NMR data of Yanzhou coal, a macromolecular structural model was constructed. In this model, benzene is the main aromatic compound and aliphatic structure exists mainly in the forms of aliphatic side chains, cycloalkanes and hydrogenated aromatic rings. The methyl proportion is similar to the total proportion of methylene and methine groups. Seventeen O atoms are present as carboxyl, carbonyl and hydroxyl groups and three N atoms exist in the forms of pyridine and pyrrole, while five S atoms in the form of thiophenic S. Molecular mechanics (MM) and molecular dynamics (MD) techniques were used to carry out energy minimization simulations on this model. The simulation results indicate that stabilization of the macromolecular structure is due to the energies of van der Waals, torsion, angle, bond and inversion in descending order of importance, and intramolecular π－π interactions between aromatic layers enables their quasi-parallel arrangement. Semi-empirical quantum chemistry (AM1) simulation indicates that the C－C bonds adjacent to carbonyl C atoms exhibit higher activity, and C atoms adjacent to S atoms and terminal C atoms are more negatively charged, which therefore prone to undergo oxidation reactions, while aromatic C atoms are characterized by fewer charges and very high stability.
Abstract: Distribution characteristics and occurrence modes of rare earth elements (REE) in oil shale from Huadian, Jilin province were determined by sequential chemical extraction process. Content of REE were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results show that the enrichment of light rare earth elements (LREE) in Huadian oil shale is richer than that of heavy rare earth elements（HREE）, relative to those in coals from China. The REE in oil shale are positively correlated with terrigenous clastic rock, and the supply of terrigenous materials is relatively stable. The fractionation between LREE and HREE is clear and shows a moderate LREE-enriched pattern. The occurrence of rare earth elements are mainly in minerals fractions. The enrichment of sulfide fractions inclines to LREE; besides, carbonate fractions, ferromanganese oxyhydroxides bound fraction and aluminosilicate bound fraction are more inclined to enrich HREE. Moreover, here is lack of the contents of rare earth elements in exchangeable and organic matter fractions. Additionally, the fractionation effects of rare REEs in different substances have some differences under various sedimentary environments
Abstract: The kinetics of chemisorption and reduction reaction of NO on coal chars was investigated using a fixed bed reactor. The effect of pyrolysis temperature (500℃~900℃) and mineral matter on the removal of NO by coal chars was also analyzed. The results indicated that coal char and NO both in temperature programmed reaction (TPR) and isothermal reaction experienced a transition from chemisorption to reduction reaction with increasing temperature (30℃~600℃). The kinetics of coal chars and NO at low temperature could be well described by Elovich equation. The initial chemisorption rate of raw coal chars increased with elevated temperature, but the value of demineralized ones first increased and then declined. The activation energy of chemisorption during isothermal process increased with the increase of NO uptakes. The NO conversions during TPR and rate constants in isothermal reduction reaction varied inversely with pyrolysis temperature. Therefore, deactivation of coal char towards NO was caused by pyrolysis at high temperature. Additionally, the mineral matter played a catalytic role both in chemisorption and reduction reaction of NO on coal chars.
Abstract: The medium temperature coal tar pitch was used as the raw material to prepare coal tar pitch powder with certain particle size distribution by freezing and then pulverizing. By adding proper amount of dispersant and water, the coal tar pitch powder was made into the coal pitch water slurry (CPWS) at high agitating speed. The screening experiments show that the JL-C01 emulsifier has the best dispersion effect. The effect of the dispersant dosage and slurry concentration on the slurry-ability, rheological behavior and static stability of CPWS were investigated. The maximum slurry-ability concentration is 70%. The apparent viscosity of CPWS firstly decreases and then increases with increasing shearing rate when the dispersant dosage is same. For different slurry concentrations, the apparent viscosity of CPWS presents a decreasing tendency with increasing shearing rate. Under the same shearing rate, the apparent viscosity goes up as the slurry concentration increases. The CPWS is a pseudo-plastic fluid. The best rheological behavior is obtained when the slurry concentration is 69%. When the slurry concentration is 70%, the slurry maintains stable for 21d. Referring to coal water slurry criterion GB/T18856-2002, the combustion analysis of CPWS was made. The low heat value, ash, and the volatile matter all meet the first grade standard for coal water slurry. In addition, the sulfur content achieves the second grade standard.
Abstract: Coal and straw were deashed by acid to make experimental samples for the combustion experiments. The effects of alkali metal potassium on the co-combustion characteristic of straw and coal were investigated by TG/DTG/DTA. The results show that KOH promotes the deashed coal and deashed blends of straw and coal to ignite, reduces the temperature of maximum loss weight rate and burning-out, but elevates the ignition temperature of deashed straw. In addition, the co-combustion of straw and coal can be fitted with the first order reaction model. Adding KOH to samples can catalyze the co-combustion and reduce the activation energy by 10kJ/mol.
Abstract: Biodiesel was prepared by the esterification of Tall oil fatty acid (TOFA) with methanol over the cation exchange resin solid acid catalyst under the assistance of ultrasonic. The preparation process and the characteristic of the biodiesel obtained were investigated; a kinetic model was built. The results showed that the ultrasonic irradiation can effectively improve the yield of biodiesel. The optimum processing condition is 65℃, reaction time of 1h, mol ratio of methanol/TOFA being 10, dehydrating agent quantity of 6% (based on TOFA) and catalyst amount of 40% (based on TOFA); under such a condition, the biodiesel yield reaches 90.0%. The kinetic parameters for the ultrasonic assisted esterification are obtained, which can well explain process regulation. Current process is economical to prepare biodiesel on the market, because cheap TOFA from black liquor is used as the raw material; it may provide a potential way to efficiently utilize TOFA.
Abstract: Vapor-phase hydrogenolysis of dimethyl oxalate to ethylene glycol was performed over a series of CuO/SiO2 catalysts with different precipitants(Na2CO3，NH3·H2O，NaOH) and CuO loading in a fixed-bed reactor at different reaction conditions. All catalysts were characterized by N2 physisorption, N2O-chemisorption, X-ray diffraction (XRD), TG and H2 temperature- programmed reduction (H2-TPR) analysis technique. The results of catalytic tests and characterization indicate that the activity of catalysts is related with the Cu0 and improved with the increase of the Cu area. High conversion of dimethyl oxalate(98%) and selectivity to ethylene glycol(87%) were obtained over the optimal CuO/SiO2 catalyst (precipitated by NaOH and 50% CuO loading) at optimized reaction conditions. The CuO/SiO2 catalyst also exhibits good stability.
Abstract: AM support was prepared by pseudoboehmite and mordenite. A series of Ni-Pt-B/AM amorphous alloy catalysts with different Pt contents were prepared by impregnation-chemical reduction method. The catalysts were characterized by XRD, ESEM, BET, ICP, XPS and H2-TPR. Benzene hydrogenation was used as probe reaction to evaluate the effect of trace Pt on the catalytic activity and stability of Ni-B/AM amorphous alloy catalyst. The result showed that the addition of Pt promoted the refinement of particles and the reduction of NiO. And the performance of hydrogenation of the catalyst was increased evidencely too. In comparison with the Ni-B/AM catalyst, under the reaction conditions of T=110℃, nNi∶nPt=150∶1.0, the activity of Ni-Pt-B/AM catalyst was further improved 82.4%. And with the addition of trace Pt, Ni-Pt-B/AM catalyst has a higher sulfur resistance and thermal stability.
Abstract: A series of ZSM-5-based catalysts with different reaction durations, i.e. fresh, used for 48h, used for 650h, used for 650h and then regenerated, as well as the regenerated one reused for another 48h, were characterized to investigate the factors that influence the stability of ZSM-5-based catalyst for the conversion of C4 olefin to propylene. The results indicted that both of the micropore volume and the BJH adsorption cumulative volume of pores are dropped after long term reaction; after regeneration, they are nearly recovered to the original values of the fresh catalyst. Meanwhile, the acid amount determined by NH3-TPD is also decreased, but it cannot be recovered after regeneration. Comparing with the results of the catalyst pretreated by steam at the same temperature, the 27Al MAS NMR results suggested that the effect of coke deposition on the pore volume can be completely eliminated through regeneration, however, the dealuminum of zeolite and the decrease of cell parameters may lead to the permanent loss of the catalyst activity. After a long duration under high temperature and water steam, the acid amount of the ZSM-5-based catalyst can be maintained at a relatively stable level, which then makes a long term stable reaction operation possible.
Abstract: MoOx-LaHY catalysts were prepared with the mixture of (NH4)6Mo7O24·4H2O and LaHY through solid-state reaction under air atmosphere and characterized by XRD and NH3-TPD techniques; their hydrodesulfurization (HDS) performance was evaluated by using the solution of dibenzothiophene (DBT, 0.6% by mass) in decane as a model reactant. The results indicated that by using solid-state reaction at 520℃, 4.36% of Mo species is incorporated into the molecular sieve LaHY, which forms the single-phase complex nMoOx·LaHY, while the rest Mo species is dispersed on the outer surface of LaHY. As a result of forming the single-phase complex, the lattice parameters of MoOx-LaHY catalysts are enlarged and their acidity is reduced. Over the sulfided MoOx-LaHY catalysts, the conversion of DBT reaches 86.74% for the HDS under the conditions of 310℃, 4.0MPa and a space velocity 20h-1. Raising the solid-state reaction temperature may increase the content of the single-phase complex incorporated in the resultant MoOx-LaHY catalysts, but it cannot significantly enhance their HDS activity.
Abstract: A series of Pd/γ-Al2O3 catalysts with various Pd loadings was prepared via incipient-wetness impregnation method under different synthesis conditions. The structural and textural properties of the synthesized catalysts were characterized by XRD, N2 adsorption/desorption, TEM, H2-TPR, and SEM-MAPS; their catalytic performance in the elimination of polycyclic aromatic hydrocarbons (PAHs) in coal-fired flue gas by oxidation was investigated. The results revealed that the PAHs removal efficiency over various Pd-loaded catalysts fluctuates between 67.3% and 93.5%; the conversion of PAHs increases with the Pd loading in the catalyst. Moreover, a better oxidation activity of these catalysts is observed for the PAHs with higher ring-cycles; nevertheless, the removal rates based on the toxicity equivalence quantity (TEQ) for all PAHs are higher than 90%. The Pd/γ-Al2O3 with a Pd loading of 0.2% and calcined at 600℃ exhibits the best catalytic performance for PAHs oxidation, with a removal rate of 93.5% at 300℃.
Abstract: NiAl mixed oxides with Ni/Al atomic ratio of 2.0, 2.7 and 4.1 were prepared by calcining the corresponding NiAl hydrotalcite-like compounds (NiAl-HLc), and applied in N2O decomposition. The NiAl mixed oxide with Ni/Al atomic ratio of 2.7 was incipiently impregnated by alkali metal (Na, K, Cs) carbonate solution to prepare the promoted NiAl mixed oxide catalysts. The catalysts were characterized by XRD, ICP-AES, FT-IR, BET, H2-TPR and XPS techniques, and their catalytic activities for N2O decomposition were tested. The effect of NiAl mixed oxides composition, alkali metal species, and potassium precursors on catalytic activity was investigated. The results show that the catalytic activity of NiAl mixed oxide impregnated by K2CO3 solution is much higher than Na2CO3 and Cs2CO3 modified catalysts; the catalytic activity of NiAl mixed oxides is largely enhanced by the addition of K species from the precursors of K2CO3, K2C2O4 and CH3COOK.
Abstract: Potassium titanates of different K/Ti ratio were synthesized by solid-phase method using TiO2 and K2CO3 as raw materials. The catalysts were characterized by SEM and XRD, and their catalytic activities were evaluated by soot oxidation reaction using TPR system. The results showed that K2Ti2O5 had good crystallinity at 850℃, and the synthesized K2Ti2O5 almost had the same degree of crystallinity using CH3COOK、KNO3 and K2CO3 as precursors of K, respectively；K2Ti2O5 of high K/Ti ratio can significantly reduce the soot oxidation temperature, the lowest ignition temperature was 280℃, and K2Ti2O5 had higher catalytic activity than the Pt-impregnated catalyst in soot oxidation.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
