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To examine the effects of water washing and acid-based deashing on the structure as well as combustion characteristics of Zhundong lignite, this study used high-speed planar laser-induced fluorescence measurements (OH-PLIF) with a specific burner and characterization techniques including XRD, BET, and ICP-AES as the method. The results indicated that both water washing and deashing can remove the ash and the main mineral alkali metals. Compared with RC, the total amount of OH release from WWC and UCC was increased attributing to the addition of combustibles and volatiles. The ignition of WWC and UCC was faster than that of RC, while the burning rate followed the opposite order. Experimental result confirms that the alkali metal and alkaline earth metals play a catalytic role in coal combustion. Meanwhile, the increase of the BET surface area and the reduction of ash are conducive to heat transfer, which is favorable for the ignition of pulverized coal. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis, as an indispensable technology, can efficiently achieve clean coal conversion. In this work, the effect of calcium-based compounds (CaO and CaCl 2) on devolatilization characteristics and gas evolution behavior of three coals were investigated by thermogravimetry-mass spectrometry (TG-MS). The catalytic mechanism was further explored in combination with the bond cleavage and gas kinetics. The results showed that both catalysts increased the weight loss rate and pyrolysis characteristic index, which also promoted the early release of CH 4 , H 2 , CO 2 and C 6 H 6 , leading to an increase on the amount of CH 4 and H 2 production. CaO had a better catalytic effect than that of CaCl 2. In addition, the kinetic results indicated that both compounds significantly reduced the activation energy of the methane I and IV stages, by 21.33%–34.66 % and 0.8%–18.60 %, respectively. And the activation energy of hydrogen III stage evolution was also reduced by 2%–18.98 % with catalysts. The calcium-based compounds tended to act on the Cal-O, Cal-Car and Car-H structures, improved the coal devolatilization behavior. The results aim to provide theoretical understanding for the practical application of catalytic pyrolysis technology. • TG-MS was used to study the devolatilization behavior of catalytic coal. • Calcium-based compounds advanced the emissions of CH 4 , H 2 , CO 2 and C 6 H 6. • Catalytic effect of CaO and CaCl 2 on the pyrolysis of different coal was discussed. • All catalysts tended to act on Cal-O, Cal-Car and Car-H structures. [ABSTRACT FROM AUTHOR]

Catalytic combustion is one of the most promising technologies to realize efficient and clean coal combustion, but its catalytic mechanism is unknown until now. This study selected three types coal to explore the influence of catalysts on the chemical structure, surface morphology, and action mechanism during combustion. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were characterized the surface chemical structure of combustion products. The results showed that the aliphatic hydrogen decreased and then increased, the content of –C O and aromaticity(I) increased, and the aromatic condensation (DOC) and C C content decreased by catalysts. Both FTIR and XPS results demonstrated that the catalysts were easy to promote the dehydrogenation condensation reaction between coal molecules, disrupting the stability of coal aromatic structure, thereby generating many free radicals and improving coal combustion. BET and scanning electron microscopy (SEM) were used to observe the effect of catalysts on the pore structure and surface morphology of combustion products. The results showed that the pore structure of product with catalysts continuously formed from micropores to medium pores and even large pores, which accelerated the oxygen transport and chemical reaction on coal surface. Finally, the mechanism of catalytic coal combustion was summarized. • The evolutionary behavior of products during catalytic combustion was investigated. • Catalysts may tend to act on -CH n and C C structures, thereby improving combustion. • Catalysts increased the contact between carbon and oxygen, making fully combustion. • The overall mechanism of catalytic coal combustion was proposed. [ABSTRACT FROM AUTHOR]

Co-combustion of coal and low-carbon fuels in boilers can reduce CO 2 emissions. Hydrogen, as a typical zero-carbon fuel, co-combusting with sludge and coal in a 660 MW tangentially fired boiler was studied by computational fluid dynamics, and combustion stability, heat transfer, and NOx formation were discussed in this research. The mixing ratio of hydrogen is 20%–60%, and in order to avoid the high rate of gas flow in local regions affecting the furnace combustion stability, hydrogen is injected into the boiler from one layer or two layers of secondary air nozzles. The impact of hydrogen on combustion affects the entire furnace, but mainly influences the upper nozzles region and the upper furnace. Flue gas temperature in the main burning region gradually decreases from 1728.8 K to 1494.6 K, as mixing ratios of hydrogen increase from 0% to 60%. The optimal case is in which the mixing ratio of hydrogen is 40% and hydrogen is injected into the boiler from two layers of secondary air nozzles, under these conditions, compared to solid fuel mono-combustion, the boiler heat flow is 1.04 times higher, and the NOx mass slightly increases at the furnace exit, about 1.13 times. [Display omitted] • The co-combustion of H 2 and solid fuel in boilers was discussed by CFD method. • The impact of hydrogen on combustion affects the entire furnace. • Increasing the hydrogen blend ratio decreases the furnace temperature. • The best way is injecting 40% H 2 into the boiler from two layers of nozzles. [ABSTRACT FROM AUTHOR]

Effects of Vortioxetine on the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (Trk B) in hippocampus of depressive rats were investigated. Forty-five SD rats were randomly divided into three groups: model control, Vortioxetine and normal control group, with 15 rats in each group. The changes of body mass were recorded within 5 weeks, and the open field test, sugar water preference test and Morris water maze test were performed to evaluate the behavior and mental status of the rats. The expression of BDNF and Trk B in rat hippocampus was detected by enzyme-linked immuno sorbent assay. Compared with the model control group, the body mass, horizontal and vertical movement, sugar and water preference rate of the vortioxetine group in the 5th week were significantly higher than those of the model control group (P<0.05), and significantly lower than those of the normal control group (P<0.05). The escape latency of the Vortioxetine group within 4 days was significantly lower than that of model control group (P<0.05), but higher than that of normal control group (P<0.05). The target quadrant residence time of the Vortioxetine group was significantly lower than that of the model control group (P<0.05), but higher than that of the normal control group (P<0.05). Expression of BDNF and Trk B in the Vortioxetine group was significantly higher than that in the model control group (P<0.05), but lower than that of the normal control group (P<0.05). Collectively, Vortioxetine can effectively alleviate the symptoms of autonomous and exploratory behavior, and reduce the decrease of learning and memory in depressive rats. Vortioxetine can increase the expression of BDNF and Trk B in depressive rats and alleviate their depressive behavior. [ABSTRACT FROM AUTHOR]

In this study, the co-combustion of Zhundong coal and NH4H2PO4 was investigated in a laboratory-scale tube furnace. The ash fusibility, combustion performance, and ash characteristics were quantified by experimental approaches. This study also used Gibbs free energy theory to analyze the chemical reactions. The results showed that NH4H2PO4 can extend the burning time of coal and reduce combustion intensity. Moreover, NH4H2PO4 significantly changed the composition of ash, which was caused by reactions between alkali/alkaline earth metals and NH4H2PO4, increasing the sodium retention ratio of the formed ash. In addition, the newly formed phosphate crystals (i.e., Mg2P2O7, AlPO4, and Ca3(PO4)2) with higher melting temperatures contributed to the increase in fusion temperature of the formed ash, and the sodium-containing crystals (i.e., Na2CaP2O7 and NaMg4(PO4)3) contributed to the increase in the sodium retention ratio. Furthermore, NH4H2PO4 had a significant effect on the microcosmic structure, with ash showing more rough and sintering being inhibited. [ABSTRACT FROM AUTHOR]

The mercury removal capacity of biochar can be improved by plasma modification and the functional group is an important factor affecting the mercury removal. This paper examines factors such as discharge voltages, gas flow rates, chlorine concentrations and discharge times that may affect functional groups on the surface of biochar. The mercury removal performance of the tobacco stem biochar prepared under different Cl2 plasma modification conditions was investigated using a fixed bed reactor. The number of C–Cl bonds and carboxyl increased after modification and decreased in mercury removal. Longer discharge times can destroy the biochar surface and possibly cause a decrease in the number of active sites. Increasing the discharge voltage promotes the formation of C–Cl bonds and carboxyl groups. Excessive gas flow rates cause active chlorine to be carried out of the reactor quickly which reduces the formation of C–Cl. The amount of C–Cl bonds increases with increased chlorine concentration. In the modified biochar, C–Cl and carboxyl take part in the adsorption of mercury to form HgCl2 and HgO, while the unmodified biochar is mainly physically adsorbed Hg0. C–Cl is the main functional group participated in mercury removal and the carboxyl is a secondary functional group. The proportion of HgCl2 is at least 68.2% in the used modified biochar. Under optimum conditions, the initial mercury removal efficiency of modified tobacco biochar was 99.1%, and the efficiency was still 79.1% after 100 min. [ABSTRACT FROM AUTHOR]

Zhundong coal (ZD), which has a high content of Na and low ash fusion temperature (AFT), causes a serious problem of slagging in boilers. P-rich municipal sludge has suitable properties for managing problems with alkali metals, but its insufficient utilization makes sludge management harder. Thus, co-combustion of municipal sludge and ZD may be a suitable approach to solve the problems. Different proportions of sludge were added to ZD at 900°C in different contents of O2 in a laboratory-scale tube furnace experimental system. The transformation of the minerals, the AFTs of residual ashes, and changes of the sodium retention ratio were investigated, respectively. The test results indicate that the ash fusibility of ZD and the sodium retention ratio can be improved because of the generated high-melting-point phosphates, such as Ca2.71Mg0.29(PO4)2, Ca5(PO4)3(OH), Ca9Fe(PO4)7, and Ca9MgNa(PO4)7. With increases in the proportion of sludge in blended samples, the AFTs increase, but the extent of the increase tends to be reduced. Modified sludge with a lower SiO2/Al2O3 ratio is more favorable for the improvement of the AFT. It is observed that 20% oxygen is the most suitable environment of those tested for co-combustion, avoiding the disadvantages of excessively high or low oxygen content. [ABSTRACT FROM AUTHOR]

The co-combustion of solid fuel and ammonia can effectively reduce carbon emissions. There is relatively little research on the co-combustion of ammonia and solid fuel in thermal power plants. The effect of ammonia distribution on co-combustion was studied by CFD simulations. Results show that in the main combustion region, solid fuel combustion with ammonia inevitably exacerbates incomplete combustion of fuels, and the maximum temperature difference in the same region of the furnace is about 18.8%. Ammonia can not only suppress NOx emissions but also promote NOx emissions, depending on the ammonia distribution method. Ammonia injected from secondary air nozzles in the top layer is the optimum distribution method of solid fuel co-combustion with ammonia. Compared to ammonia injected from secondary nozzles in the bottom layer, the emission of NOx is decreased by about 16.3%. This study will provide guidance and a theoretical basis for discussing the feasibility of co-combustion of solid fuel and ammonia in utility boilers. [Display omitted] • Solid fuel combustion deteriorates near the ammonia nozzles. • The maximum temperature difference in the same region is about 18.8%. • Increase ammonia nozzles' height, the outlet NOx mass decreased by about 16.3%. • Ammonia injection from top nozzles is the optimum ammonia distribution method. [ABSTRACT FROM AUTHOR]

A series of MnOx-CeO2/ZSM-5 catalysts with different Ce loadings were prepared through the impregnation method and characterized by BET, XRD, SEM, H2-TPR, and XPS. The performances of selective catalytic reduction (SCR) of NO/NO2 with NH3 and NO oxidation over MnOx-CeO2/ZSM-5 catalysts were investigated. The result showed that the MnOx dispersions, redox abilities and proportions of Mn4+ of catalysts were enhanced by the doping of CeO2. However, the excessive Ce loadings led to the accumulation of active components on the catalyst surface. The sample with Ce/Mn molar ratio of 0.39 exhibited the best SCR performance, the NOx conversion achieved 95.4% at 150 °C, and maintained higher than 95% in a wide operating temperature range (150-350 °C). MnOx-CeO2/ZSM-5 also exhibited considerable catalytic performance of NO oxidation, the maximum conversion of NO achieved 56.5% at 350 °C. [ABSTRACT FROM AUTHOR]

NO conversion using dielectric barrier discharge (DBD) plasma with different catalysts was investigated. Cu/TiO2, Cu/Al2O3, Cu/ZSM-5, Cu/CNTs and Cu/AC catalysts were prepared by incipient wetness impregnation with 4 wt% Cu loaded. BET, SEM, XRD, XPS, H2-TPR, NH3-TPD were used to measure and evaluate various catalysts. Compared with the plasma only process, the combination of plasma with different catalysts significant improved the NO conversion rate. The highest NO conversion rate of 76% could be achieved with Cu/ZSM-5 catalyst at the energy density of 184 J/L. The results indicate that Cu species over the support ZSM-5 can produce high concentrations of CuO, largest specific surface area, largest amounts of acidity and lowest reduction temperature (209 °C), these factors conducive to plasma-catalyst reaction. Besides, Cu/TiO2 and Cu/Al2O3 catalysts exhibited excellent NO conversion at the low energy density because of the low thermal stability. After plasma-catalyst reaction, the reducibility of CuO and Cu2O over supports decreased and the peak position of acid sites shifted to lower temperature. [ABSTRACT FROM AUTHOR]

The dielectric barrier discharge synergy with 10 wt% MnO/TiO-MWCNTs was investigated with different proportions of support materials. All as-prepared catalysts were analyzed by BET, ICP-AES, SEM, XRD, XPS, Raman spectroscopy and H-TPR. The MnO/TiO-MWCNT (1:4) catalysts exhibited the best catalytic activity with NO removal efficiency of 72.4% at the discharge power of 45 W when temperature was ambient. This was a result of the extremely dominant phase of MnO (76.21%), the high concentration of lattice oxygen (74.92%) and the good dispersion of manganese oxides on the surface of the catalysts, as proven by the characterization methods used in this study. Our XPS and ICP-AES analysis illustrated that manganese oxide particles could be decorated on the internal channels of MWCNTs, which was found to be abundant with the increasing MWCNTs and exhibited better ability to adsorb NO and supply oxygen. According to the sulfur poisoning experiment, a small amount of SO (the concentrations of SO and NH were 1000 and 500 ppm, respectively) could facilitate the SCR catalytic performance by generating sulfate species on the surface of the carbon, which was regarded as a Brønsted acid site on the surface of the catalyst. [ABSTRACT FROM AUTHOR]

Manganese-copper bimetal oxide catalysts supported on ZSM5 and acid-treated multi-walled carbon nanotubes (MWCNTs) were produced by incipient wetness impregnation for selective catalytic reduction of NO with dielectric barrier discharge plasma. Plasma can activate molecules even at ambient temperature, generating active oxygen species such as O, O, and HO radicals, which can oxidize NO to NO effectively. The SCR activity of Mn-Cu/MWCNTs was studied and compared to that of the Mn-Cu/ZSM5. The obtained samples were characterized by XRD, SEM, TEM, ICP, H-TPR, Raman spectroscopy, and XPS. The results show that Mn -Cu/MWCNTs catalyst possesses NO removal activity superior to that of the Mn -Cu/ZSM5 catalyst. MWCNTs-based catalyst attains NO removal efficiency of 88% at 480 J/L, while the ZSM5-supported catalyst achieves NO removal efficiency of 82% at the same energy density. The oxygen content increased from 3.33 to 19.07% on the nanotube surface after introducing Mn and Cu, which almost remained unchanged on ZSM5. The oxygen-containing functionalities are important for NO adsorption and removal. Moreover, the characterization revealed that CuO is the main phase of copper oxide, but copper dispersion decreases on Mn -Cu/ZSM5 surface because of the formation of copper dimer species. The manganese is well-dispersed on the catalysts, MnO and MnO contents of Mn -Cu/MWCNTs are larger than that of Mn -Cu/ZSM5, MnO is the predominant phase of manganese oxide. [ABSTRACT FROM AUTHOR]

Molecular modeling research based on transition state theory and density functional theory was performed to clarify the mechanisms for NH3evolution during the reaction of H2with char edge models containing 2-pyridone in zigzag and armchair configurations. The thermal chemical activation energy and enthalpy change were calculated in the overall process of NH3formation. The results indicate that formation of −NH2radicals is possible for both char edge models containing 2-pyridone in the zigzag and armchair configurations. Then, NH3can be produced through homogeneous hydrogen abstraction. It is found that the reaction of releasing NH3can be completed relatively easily with the char edge model containing 2-pyridone in the armchair configuration. Most pathways for NH3evolution appear to involve endothermic reactions for both configurations. These results provide a reference and basis for controlling the emission of nitrogen oxide. [ABSTRACT FROM AUTHOR]

The construction of a power plant using a 660 MWe supercritical circulating fluidized bed (CFB) boiler with co-combustion of coal and gangue has been proposed in China. Therefore, this study simulated the distribution law and transformation mechanism of sulfur-containing phases using three low-calorific samples of gangue and coal mixtures under different conditions, based on the thermodynamic simulation software HSC Chemistry. The results showed that sulfur low in calorific value coal is mainly converted into gas phase SO2, solid phase alkali metal sulfate (Na2SO4 and K2SO4), and alkaline earth metal sulfate (CaSO4 and MgSO4) in an oxidizing atmosphere. Under a reductive atmosphere, sulfur in coal is mainly converted into gaseous H2S, COS (Carbon oxysulfide), and solid FeSx. With an increase in the O/C ratio, the distribution curve of sulfur-containing substances contracted to lower temperatures. It was established that the sulfur fixation capacity of coal ash depends on the relative amounts of basic oxides and sulfur present in it. Relevant conclusions were also verified and compared to those of the laboratory small-fluidized bed test bench and the 3 MWth CFB combustion test bench. [ABSTRACT FROM AUTHOR]

The Flame pyrolysis method used to synthesize carbon nanotubes was studied in this work. In order to improve the quality of synthesized carbon nanotubes, it is important to change the corresponding natures of the catalyst. Two catalyst preparation methods, namely, the sol-gel method and the impregnation method, were compared in this experiment. The properties of the catalyst are analyzed in depth by energy dispersive spectrometer (EDS), x-ray diffraction (XRD), temperature program reduction (TPR). The generation of carbon nanotubes was systematically analysed through scanning electron microscope (SEM), molecule dynamics (MD), raman spectroscopy and transmission electron microscope (TEM). The results show that the catalysts prepared by the impregnation method are stickier, dispersed and easier to dip onto the probe or substrate, which is beneficial for the large-scale production of carbon tubes. The specific surface area of alumina is larger and the iron and molybdenum oxide are more evenly dispersed on the surface of alumina. The carbon nanotubes produced by the catalysts prepared by impregnation method are flatter and have less impurities. The ratio of ID/IG+ is 29.7% lower than that of the sol-gel method in the Raman spectra. The TEM statistics show that the average diameter of the carbon tubes decreases by 23.3%. Therefore, the impregnation method can improve the quality of carbon nanotubes in the case of a similar degree of difficulty in the preparation of the catalyst. [ABSTRACT FROM AUTHOR]