Abstract: The pyrolysis characteristic of blended coal and the interaction between Shenmu coal (SMC) and caking coals(Fat coal-FM, gas coal-QM, coking coal-JM) were studied by temperature-programmed thermobalance. The pyrolysis kinetics were analyzed using distributed activation energy model (DAEM). The results indicate that the concentrated release rate of moisture increases and temperature corresponding to the release peak of volatile matter(tmax) for coal blends decreases as increasing SMC blending ratio. The inhibition of blended coal is reduced as increasing SMC blending ratio when pyrolysis temperature surpasses the solidified temperature of metaplast (>460-480 ℃), indicating a poor bonding behavior of metaplast. In addition, the inhibition of blended coal is enhanced and its bonding behavior is improved with increasing heating rate. The effects of relieving swelling pressure and improving dispersity of metaplast gradually reduce as deepening the metamorphic degree of caking coal from QM, FM to JM, since the corresponding temperature for promoting interaction (release of volatile) is below, within, above the plastic temperature range of caking coals, respectively. A comparison of experimental and calculated distributed activation energy model confirms the interaction mechanism of blended coal during co-pyrolysis.
Abstract: The mineral inter-reaction of blending coals during O2/CO2 combustion was studied. Two coals, Meng coal and Pingqi coal, were blended by certain ratios. The blending coals were burned in a tube furnace with O2/CO2 or O2/N2. Ash fusion temperature test, XRD, TG/DSC and thermodynamic calculation were employed to examine the melting behavior and mineral reactions of blending coal ashes during O2/CO2 and O2/N2 combustion in detail. The results show that:there is no a pronounced difference in the blending coal ash fusion temperature between O2/CO2 and O2/N2 combustion. More CaCO3 produced during O2/CO2 combustion suggests that O2/CO2 atmosphere significantly prevents the decomposition of CaCO3. The changing of atmosphere has an impact on the transformation of Ca-containing minerals, and the reaction between Ca and mullite occurs significantly, which is easier in O2/CO2 combustion to produce more low-melting phase that will aggravate the boiler slagging. When the blending ratio of Meng coal in blends with Pingqi coal is 75% or more, less mullite is present in blending coals, and thus the impact of atmosphere on Ca-mullite reaction is weaker. However, the atmosphere has a more impact on Fe-containing minerals and more Fe-glass phase will be formed during O2/CO2 combustion, which will aggravate the boiler slagging.
Abstract: Tire pyrolysis char (TPC) was used as a carrier to prepare Ni/TPC catalyst by homogeneous precipitation method. The characteristic of synthetic catalyst was determined by EDX, SEM, XRD, TG and BET. Meanwhile, the performance of Ni/TPC catalyst including reforming temperature, holding time, nickel loading and usage time on the straw pyrolysis gas reforming was investigated in a tube furnace. The results showed that TPC was rich in char and metal. Ni was well loaded on TPC which had a good thermal stability with a specific surface area of 62 m2/g. The Ni/TPC catalyst could obviously improve the burning gas content. The highest catalytic efficiency was obtained at reforming temperature of 750 ℃ and 10 min holding time with 30% Ni loading. The content of H2 in the gas was high and relatively increased by 50% after using the catalyst for 850 min. The Ni3ZnC0.7 active component structure converted to FeNi3 after long-term used with high and stable catalytic activity. TPC had the ability to be a new type of carrier for nickel catalyst.
Abstract: The oxide of gallium was prepared by homogeneous precipitation in organic solvent. The physical structure and surface properties were characterized by XRD, NH3-TPD, TEM and BET. The results reveal that γ-Ga2O3 was obtained after 500 ℃ heat treatment of the precursor of GaOOH. The lattice type of the γ-Ga2O3 is similar to that of γ-Al2O3, which belongs to cubic, cation-deficient spinel structure. The γ-Ga2O3 has a moderate acid center with larger amount of acid content. Most of the γ-Ga2O3 is two-dimensional nanoflakes with thickness of 10 nm and diameter of 100 nm. These nanoflakes are mainly distributed in one direction, and some of them form petal-shaped patterns. The experimental results showed that the conversion rate of dimethyl ether (DME) was about 24% at 270 ℃, which was close to equilibrium conversion. The texture properties of the catalyst had no significant change after the reaction and the specific surface of the catalyst was about 130 m2/g. The composite catalyst composed of the γ-Ga2O3 and Cu-based catalyst was used to DME steam reforming reaction in slurry bed at 270 ℃. The conversion of DME and selectivity of H2 were as high as about 99% and 68%, respectively. The conversion of DME was over 95% after reaction time of 200 h.
Abstract: Considering the tunable structure of hydrotalcite-like compounds, co-precipitation method was employed to synthesize Ni/CaO-Al2O3 composite catalysts. The influence of calcination temperature on the structure and catalytic reforming performance of Ni/CaO-Al2O3 catalyst investigated. The results showed that the specific surface area and Ni particle size of the as-synthesized composite catalysts were greatly affected by calcination temperature of the precursor derived from the variable interaction between the Ni and the support. When the calcination temperature was 700 ℃, the composite catalyst obtained a specific surface area of 21.42 m2/g and Ni particle size of 19.51 nm. The catalytic evaluation showed that the composite catalyst possessed a H2 concentration of 98.31% and a CH4 conversion of 94.87%, and H2 concentration exceeded 97.35% even after 10 cyclic runs. The high catalytic activity was ascribed to the higher specific surface area, which provided more active sites and enhanced CO2 sorption. The smaller Ni particle size improved the anti-sintering capacity of the composite catalyst, endowing the composite catalyst superior stability.
Abstract: ZSM-5 catalysts with same particle size and different Si/Al molar ratio were synthesized successfully by hydrothermal synthesis method, and then, Fe-Cu-K-containing ZSM-5 samples were prepared via aqueous incipient wetness impregnation. The effect of Si/Al molar ratio on the FTO reaction was systematically investigated. The results indicated that the conversion of CO and selectivity to light olefins strongly depended on the reaction conditions and the acidic properties of the zeolite. The ZSM-5/FeCuK catalyst with a Si/Al molar ratio of 50 possessed the highest CO conversion (84.71%) and selectivity to light olefins (32.08%) compared with others. H2-TPR results showed that the reduction of Fe phase in Z50/FeCuK was the highest. With the combination of DRIFTS, TG-DTA and XRD techniques, it was found that there were more carbonate and hydrocarbon species adsorbed on the surface of Z50/FeCuK and more FeCx phases were formed after reaction compared with the other catalysts. Finally, the reaction conditions were optimized and the results showed that the catalyst had the best performance at 310 ℃, H2/CO(volume ratio)=2 and 1.0 MPa.
Abstract: Cu/SiO2 catalysts were prepared via ammonia evaporation method, using fumed silica (SiO2-aer), silica gel (SiO2-gel) and alkaline silica sol (SiO2-sol) as the silica sources and their catalytic performance in methanol decomposition were investigated. The catalysts were characterized by N2 adsorption-desorption, N2O chemisorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), H2 temperature programmed reduction (H2-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that silica source can affect the decomposition activity of Cu/SiO2 catalysts. The Cu/SiO2-sol catalyst prepared with alkaline silica sol exhibits larger surface area, smaller active site size and more uniform dispersion of Cu. Therefore, it gives Cu/SiO2-sol a better decomposition performance than other catalysts. Methanol conversion on Cu/SiO2-sol is 10% higher than that on Cu/SiO2-aer, and 7% higher than that on Cu/SiO2-gel. Additionally, byproducts concentration on Cu/SiO2-sol is considerably lower than other catalysts. Under the reaction conditions of 280 ℃, 1 MPa and 0.6 h-1 of WHSV, methanol conversion of 98.4% and gas yield of 96.7% can be achieved.
Abstract: SBA-15 with the removal of template agent, which served as both the silicon source and indirect template agent, was used to hydrothermally synthesize hierarchical SAPO-11 molecular sieve. The crystal structure, morphology, acidity and texture of the samples were characterized by XRD, SEM, FT-IR and N2 physical adsorption. The results showed that the pure SAPO-11 can be obtained by using calcined SBA-15 as the silicon source. At the same time, SBA-15 was completely transformed in the synthesis system. The obtained SAPO-11 sample showed a hollow near-column shape with particle size of about 1-3 μm, which was composed of bar-shape structure with a width of about 100 nm. Compared with conventional SAPO-11 synthesized by adopting white carbon black or colloidal silica as the silicon source, the addition of SBA-15 successfully introduced mesoporous channels with pore size of 5-10 nm into SAPO-11 molecular sieve. Moreover, the proportion of moderate and strong Brønsted acid was larger than that of weak Brønsted acid. Finally, the catalytic behaviors of Pt/SAPO-11 bifunctional catalysts were investigated in the hydroisomerization of n-dodecane. The results indicated that the hierarchical catalyst synthesized with SBA-15 was much more active and selective. The excellent isomerization performance was closely related to the acidity and pore structure of the hierarchical SAPO-11 molecular sieve. The increase of moderate and strong Brønsted acidity contributed to the improvement of activity. Meanwhile, the mesopores were conducive to the significant increase of selectivity via accelerating diffusion of the isomerization products.
Abstract: The adsorption isotherms and kinetic curves of toluene on a series of hierarchical mordenite zeolites with different mesoporosities were measured to investigate the effect of hierarchical pore structures of mordenite on the adsorption and kinetics. The isotherms of hierarchical mordenites show the combination of characteristics of both micropore and mesopore adsorption. Furthermore, the fitting of experimental isothermal data of toluene reveals that the isotherms of toluene can be well described by dual-sites Toth-type model. The fitting parameters and the Henry's constants (KH) and the initial heats of adsorption (Qst) calculated show that the introduction of mesopores into mordenite weakens the interaction between toluene and zeolitic surface. Additionally, the adsorption kinetic curves show that the adsorption rates of toluene on hierarchical mordenite are much larger than that on microporous mordenite, revealing the enhanced effect of mesopore on the mass transfer in zeolites.
Abstract: With hexadecyl trimethyl ammonium bromide (CTAB) as the template, cobaltosic oxide precursors were hydrothermally synthesized. Co3O4 catalysts were then prepared by calcining the cobaltosic oxide precursors, which was further modified by impregnation with K2CO3 solution and used in the decomposition of N2O. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD); the effect of CTAB concentration, CTAB/cobalt molar ratio and urea/cobalt molar ratio on the catalytic activity of Co3O4 was investigated. The results indicated that the Co3O4 catalyst prepared by using 0.05 mol/L CTAB solution, with a CTAB to cobalt molar ratio of 1 and a urea to cobalt molar ratio of 4, exhibits high activity in N2O decomposition. The catalytic performance of Co3O4 can be further enhanced by modifying with K. Over the 0.02 K/Co3O4 catalyst, the N2O conversion remains over 91% at 400 ℃ after conducting the N2O decomposition reaction for 50 h in the presence of oxygen and steam.
Abstract: A complex catalyst was prepared by loading MnOx-CeO2 and urea on spherical activated carbon (SAC) for the selective catalytic reduction (SCR) of NO at low temperature (30-90 ℃) in the absence of ammonia. The complex catalyst was characterized by scanning electron microscopy-energy dispersive spectrum (SEM-EDS), X-ray diffraction (XRD), and N2 sorption. The results show that at 30-50 ℃, the micropores of SAC acts as the main active sites for NO adsorption and reaction, whereas at 70-90 ℃, MnOx-CeO2 turns to be the main active sites for NO adsorption and reaction; the urea-SCR activity is enhanced by MnOx-CeO2 in a wide temperature range. Over the complex catalyst loaded with 8% Mn (the mole ratio of Mn to Ce is 1) and 10% urea, the steady conversion of MOx reaches 85.6% in the absence of ammonia, under the conditions of 90 ℃, 0.05% NO, 20% O2 and a space velocity of 6000 h-1.
Abstract: A series of supported Mn-Ce-based catalysts were prepared using TiO2, SAPO-34, and Al2O3 as supports. The physicochemical properties of the obtained catalysts, such as structure, specific surface area, reduction properties, surface elements and acidity were characterized with XRD, BET, H2-TPR, XPS and Py-FTIR. The results showed that MnCeOx/SAPO-34 catalyst exhibited a larger specific surface area (439.87 m2/g), medium amount of Lewis acid sites and the weakest reduction property. In the MnCeOx/Al2O3 catalyst, the concentration of Mn4+ and Ce3+ was relatively high, and the amount of acid sites is the lowest. However, TiO2 as the catalyst support could enhance the reduction property, and increase the amount of Lewis acid sites and the concentration of Mn and Ce. NH3-SCR performances of the catalysts were evaluated using a flow type fixed bed reactor. The results showed that MnCeOx/TiO2 catalyst presented the best catalytic performance, over which near 100% NO conversion was reached at 280 ℃ under a gas hourly space velocity of 42000 h-1. The combination of characterization and reaction results indicated that the good reduction behavior and large amount of Lewis acid sites were beneficial to the enhancement of the catalytic performance for low-temperature NH3-SCR reaction.
Abstract: The Co/Fe/Al2O3/cordierite catalysts with different Co loadings were prepared by sol-gel and impregnation methods, and their performance in the selective catalytic reduction of NO with C3H6 over catalytic were experimentally studied in a ceramic tubular reactor. The results indicated that 1.5Co/Fe/Al2O3/cordierite showed the highest C3H6-SCR activity with 97% NO reduction in the simulated flue gas at 550 ℃. Cobalt was able to effectively improve the ability of Fe/Al2O3/cordierite catalysts to resist SO2 and H2O in flue gas. When 0.02% SO2 and 3% water vapor were added to the simulated flue gas, the NO reduction efficiency of 1.5Co/Fe/Al2O3/cordierite was almost unaffected, the NO reduction by 1.5Co/Fe/Al2O3/cordierite with C3H6 all surpassed 90%. In contrast, the catalytic activity of Fe/Al2O3/cordierite without cobalt modification was seriously suppressed by SO2 and H2O, the highest NO reduction efficiency of Fe/Al2O3/cordierite was less than 50% within the entire reaction temperature range (200-700 ℃).XRD and SEM results showed that the surface of 1.5Co/Fe/Al2O3/cordierite after the modification by cobalt became loose, and formed by the cobalt iron and cobalt aluminum metal oxide-based spherical grains.H2-TPR results showed that 1.5Co/Fe/Al2O3/cordierite had better low temperature reduction performance than Fe/Al2O3/cordierite. Py-FTIR results confirmed that Co can dramatically increased the Lewis acid and produced Brønsted acid on the catalyst surface. N2 adsorption/desorption characterization results proved that Co can increase the specific surface area of the catalyst.
Abstract: The mesoporous molecular sieve SBA-15 was prepared by hydrothermal synthesis, modified with the ultrasonic immersion by (CH3COO)2Co and with the introduction of the amino group into it with APTS as silane coupling agent, and characterized by SEM, XRD, FT-IR, BET and XPS. The prepared Co-NH2-SBA-15 was used for adsorption of H2S at normal temperature. The results show that both amino group and metal have been introduced into the molecular sieve. When the molar ratio of amino group to silicon is 0.20 and the Co loading is 8%, the adsorption capacity of SBA-15 is the highest. Under the conditions of the volume fraction of hydrogen sulfide of 227 μL/L, the temperature of 25 ℃ and the gas flow rate of 75 mL/min, the capacities of breakthrough sulfur and saturated sulfur come to 0.151 and 0.190 mmol/g, respectively. Moreover, the adsorbent can be regenerated for recycle. Under the assistance of molecular sieve surface being grafted by amino group and impregnated by metal, the adsorption capacity can be improved and the stability of molecular sieve can be enhanced.
Abstract: The effects of both the concentration of corn stalk hydrolysis solution and the volume of activated sludge as an anode substrate on the performance of the double chamber microbial fuel cells (MFCs) were investigated. The double chamber MFCs were built with K3[Fe(CN)6] as the catholyte. The results show that with the increase in the activated sludge volume from 1.5 to 6.0 mL, the electricity generation of MFCs increases gradually, but it decreases when the activated sludge volume reaches 7.5 mL. As the mass concentration of corn stalk hydrolysate is 0, 10, 15, 20, 30, 40 g/L, the stable voltage of MFCs is 54, 157, 248, 208, 170 and 146 mV, respectively. The best performance of MFCs is obtained with the power density of 54.6 mW/m2 and the internal resistance of 496 Ω as the activated sludge volume is 6 mL and the corn straw hydrolysate is 15 g/L. Moreover, the cyclic voltammetry curve (C-V) and electrochemical impedance spectroscopy (EIS) tests prove that the electrode process is controlled by both the charge transfer and the diffusion process, while the reaction process is controlled by the electron transfer.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
