Abstract: The effects of different Fe, Cr and Mn additives on the desulfurization of coking coal with high sulfur during coking process were investigated by crucible coke. Also, the effects of the additives on the desulfurization during coal pyrolysis and the evolution of sulfur-containing gases under different atmospheres were examined in a fixed bed reactor. The results indicate that the effects of additives on the sulfur forms of coal are different. Fe3+ which has an oxidability decreases the pyrite content of coal while other additives have little effect on the sulfur forms of coal. Chromium additives increase the desulfurization of coal pyrolysis, but iron and manganese additives decrease that during simulated coking process. The pyrolysis of Cr3+ loaded Jiexiu coal indicates that the desulfurization of coal with Cr3+ under N2 is restrained and the evolution of sulfur-containing gases is decreased, and the unstable organic sulfurs are converted to stable organic sulfurs; on the other hand, the desulfurization of coal with Cr3+ is facilitated under reductive atmospheres and the yield of sulfur-containing gases is obviously increased. The effects of the simulated coke oven gas (SCOG) on the desulfurization of coal with additives and the evolution of sulfur-containing gases during pyrolysis are similar to those of H2, so SCOG can be used as the reaction atmosphere for increasing the desulfurization during pyrolysis with transition metals additives.
Abstract: To investigate the relationship between microstructure of rapid pyrolysis chars under different temperatures and their gasification reactivities, three Chinese typical coals with different ranks were pyrolyzed in a drop-tube furnace at 800~1 400 ℃. The structure of chars obtained was characterized by using XRD (X-ray diffraction) and N2 gas adsorption method, and the CO2 gasification reactivity of chars was examined using TGA (thermogravimetric analyzer). The results show that the specific surface area increases with the increasing of pyrolysis temperature and reaches maximum value at 1 200 ℃, while the gasification reactivity of NM lignite and SF bitumite chars lowers relatively. The gasification reactivity of ZY anthracite char increases gradually at 800~1 200 ℃, while the maximum value of specific surface area appears at 900 ℃. It is proved that there is not a good correlation between the specific surface area and the gasification reactivity of chars. However, the change of gasification reactivity of three chars with increasing pyrolysis temperature is in accordance with the development of carbon crystallite structure of chars which reflects the graphitization progress of chars. It is concluded that the change of carbon crystallite structure of chars has a greater influence on the gasification reactivity of chars made by rapid pyrolysis.
Abstract: Pyrolysis of two typical Chinese coal liquefaction residues (Shenhua and Shengli) and their solvent extracts was carried out by TG. The results show that Shenhua and Shengli residue contain similar content of light component, and their weight losses in TGA are similar. However, the different composition of light component in the two residues leads to their difference in TG curves. As increasing of heating rate, the maximum weight loss rate and its corresponding temperature increase. The calculated weight loss calculated from the constitutes is approximately the actual value of the residue. From the kinetic analysis, it is found that the weight loss calculated by the experimental E and k0 agree well with that obtained from the experiment. The weight loss is mainly caused by evaporation of volatile matter which can be extracted by solvent.
Abstract: The product distribution and reactivity of coal pyrolysis at temperatures up to 850 ℃ and in atmospheres containing O2 and steam were studied. The effects of reaction temperature, equivalent air ratio (ER) and the mass ratio of steam to coal (S/C) were examined. The gas yield increased with the increases of the temperature, ER and S/C, whereas the yields of char and tar correspondingly decreased. When O2 was present in the atmosphere, the CO2 and CO productions obviously increased, while that of H2 decreased. The simultaneous presence of O2 and steam in the atmosphere improved the specific surface area and reactivity of the resultant char. However, the gasification reactivity of char produced at 900 ℃ in N2 and/or in an atmosphere with an ER 0.22 at 850 ℃ was low because of occurrence of carbon graphitization. The inclusion of O2 and steam into the atmosphere had a great effect on the tar properties. Compared with pyrolysis in pure N2, the tar produced in O2 and steam contained fewer single-ring aromatics and phenolic, ketonic and aliphatic hydrocarbons, which made the tar more reactive for cracking and reforming.
Abstract: The phosphorus content of sewage sludge ash is higher than that of Shenfu coal, and its main phosphoric crystalline minerals are calcium iron phosphate and a certain amount of aluminum phosphate. The volatilization of phosphorus during co-pyrolysis of sewage sludge and Shenfu coal was studied with a high frequency furnace reactor in laboratory scale. It has been found that after pyrolysis most of the phosphorus in fuels is deposited in char. The volatilization ratio of phosphorus increases at first and then decreases with the increase of sewage sludge ratio in fuels. And it monotonically increases with the pyrolysis temperature. Organophosphorus compounds make up the main part of volatized phosphorus when pyrolysis temperature is less than 1 100 ℃ and its volatilization ratio is lower than 3.2%. Inorganic phosphorus does not volatilize obviously until 1 200 ℃, and the highest volatilization ratio of phosphorus is 33.0% at 1 300 ℃.
Abstract: The reduction of NOx emission via different coal combustion methods was studied in a two-stage reactor using 3 different coals. The NOx formation is effectively suppressed by reburning the gas from pyrolysis and partial gasification of coal, making the NOx emission obviously lower than that of the air-staged combustion. It is found that the decoupling combustion leads to the higher NOx reduction rate, which is over 32% in comparison with the normal combustion. The NOx reduction rates vary with the coal properties. The smaller the fuel ratio (fixed carbon to volatile matter)at per nitrogen content in coal, the lower NOx emission is for reburning the combustible gas from pyrolysis and gasification and also for the decoupling combustion. The NOx emission due to reburning the partial gasification gas varies with the oxygen amount applied in the gasification, and the lowest NOx emission is realized in the oxygen concentration from 8% to 10%. A 1.4 MW industrial boiler was designed according to the principle of the decoupling combustion technology. The running data for the same coal show that the decoupling combustion reduces 32.9% NOx emission in comparison with the traditional combustion.
Abstract: The effects of mixing conditions on the properties of mixed asphalt were examined, including mixing temperature, mixing time, stirring method and coal pitch particle size. Especially, the anti-aging properties, rheological properties and storage stability of the selected samples were investigated. The results show that mixed conditions have an important effect on the dispersion of coal pitch in petroleum asphalt. With the increasing of mixing temperature and time, the dispersion of coal tar pitch in the petroleum asphalt is enhanced, but it also brings about the aging of based asphalt. The particle size of coal pitch has more important effect on the properties of mixed asphalt. The tests of the selected samples indicate that mixed asphalt have good properties of rheological behavior at high temperature, anti-oxidation aging and storage stability.
Abstract: The gasification reactivities of chars generated from the pyrolysis of corncob and its acid hydrolysis residue (AHR) were investigated by using a thermal gravimetric analyzer (TGA). The effects of pyrolysis temperature, heating rate, gasification temperature and gasification agent (CO2 and H2O) on the gasification reactivities were examined, and the char morphology was characterized by means of scanning electron microscopy (SEM). The results show that the AHR char performs lower gasification reactivity than the corncob char does in both steam and carbon dioxide. The gasification reactivity of AHR char decreases with increasing the pyrolysis temperature from 550 to 850 ℃, but increases when the pyrolysis heating rate increases from 0.1 to 15.0 K/s. The gasification reactivity of AHR increases with increasing temperature, and the steam gasification reactivity of AHR char is higher than the CO2 gasification reactivity at gasification temperatures between 850 and 950 ℃. The gasification kinetic parameters based on a mixed reaction model were calculated.
Abstract: The Ni-based monolithic catalyst was prepared by impregnation method. The performance of the catalyst on biomass fuel gas reforming was investigated by varying the reaction temperature, space velocity, steam addition and time-on-stream. Results show that the Ni-based monolithic catalyst exhibited only CO hydrogenation activity as the reaction temperature is lower than 500 ℃. With the increase in reaction temperature, the reforming activity increased gradually. The CH4 or C2 conversion was above 95%, and CO2 conversion was about 92 % over the catalyst at higher temperature (≥800 ℃). However, increasing space velocity and the addition of water steam resulted slightly in the decrease of reforming activity. Additionally, with increasing water steam content the H2/CO volume ratio in synthesis gas increased gradually from 0.85 to 4.00. According to the characteristic of X-ray diffraction, it was found that the formation of Nio could promote well the reforming reaction.
Abstract: Direct decomposition of methanol has been investigated using gliding arc gas discharge (GRD) at atmospheric pressure. Depending on the experimental conditions of Ar flow rate, methanol concentration, the electrode gap, input voltage and vaporization room temperature (VRT), different conversions are achieved ranging from 51.0% to 81.7%. Interestingly, the selectivity to the production of hydrogen and carbon monoxide is kept almost constant under all the experimental conditions. The formation of little methane and C2Hx as a byproduct, and trace quantity of carbon dioxide are detected. The reaction channels of methanol decomposition induced by GRD plasma is proposed in detail.
Abstract: Replacement of phosphoric acid electrolyte by phosphosilicate gel based electrolytes is proposed for performance enhancement of phosphoric acid fuel cell (PAFC). Phosphosilicate gel in paste form and in powder form is synthesized from tetraethoxysilane and orthophosphoric acid using sol-gel method for two different P/Si ratio of 5 and 1.5 respectively. Replacement of phosphoric acid electrolyte by phosphosilicate gel paste enhances the peak power generation of the fuel cell by 133% at 120 ℃ cell temperature; increases the voltage generation in the ohmic regime and extends the maximum possible load current. Polyinyl alcohol (PVA) is used to bind the phosphosilicate gel powder and to form the hybrid crosslinked gel polymer electrolyte membrane. Soaking the membrane with phosphoric acid solution, instead of that with water improves the proton conductivity of the membrane, enhances the voltage and power generation by the fuel cell and extends the maximum possible operating temperature. At lower operating temperature of 70 ℃, peak power produced by phosphosilicate gel polymer electrolyte membrane fuel cell (PGMFC) is increased by 40% compared to that generated by phosphoric acid fuel cell (PAFC). However, the performance of composite membrane diminishes as the cell temperature increases. Thus phosphosilicate gel in paste form is found to be a good alternative of phosphoric acid electrolyte at medium operating temperature range while phosphosilicate gel-PVA composite offers performance enhancement at low operating temperatures.
Abstract: In the current study simultaneous reactions of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic (Co-Mo/Al2O3 and Ni-Mo/Al2O3) and tri-metallic (Pd-Co-Mo/Al2O3 and Pd-Ni-Mo/Al2O3) catalyst systems which were prepared by incipient impregnation method. In situ hydrogen utilization and low Pd loadings were the major targets of this study. For comparison purpose, catalytic activity was separately determined for both the methanol reforming and HDS of DBT reactions as well. Ni based catalysts were confirmed with better activity than Co ones for both the reactions with Pd promoted ones ranking at the top i.e. Pd-Ni-Mo/Al2O3 > Ni-Mo/Al2O3 > Pd-Co-Mo/Al2O3 > Co-Mo/Al2O3 where Pd-Ni-Mo/Al2O3 showed 91% DBT conversion at 380 ℃ and 12 h reaction time. Some of the selected organic additives on catalytic activity were tested for their effect toward HDS reaction which was unique with close relation to their chemical nature. Reaction products were quantitatively and qualitatively analyzed via HPLC and GC-MS techniques respectively which helped in elucidating reaction mechanism.
Abstract: Experiments of perhydrophenanthrene cracking over zeolite catalysts were conducted in a small fixed fluidized bed (FFB) unit. Effects of Y and ZSM-5 zeolite catalysts, temperature and catalyst/oil ratio on naphthenic ring opening reactions of perhydrophenanthrene were examined. The results show that products from naphthenic ring opening reactions of perhydrophenanthrene over zeolite catalysts are monocyclic or dicyclic cycloparaffin (cyclohexane, decalin), which is further converted into isoparaffin (2-methylpenptane, methyl hexane) by side chain breaking, or into monocyclic aromatics (benzene, C1~4 alkyl benzene) by hydrogen transfer, or into dicyclic aromatics (tetrahydronaphthalene, naphthalene, alkyl naphthalene) by deep hydrogen transfer. Products from dehydrogenation condensation reactions of perhydrophenanthrene are polycyclic aromatics with more than 3 rings (phenanthrenes, pyrenes) and coke. Due to the influence of naphthenic diffusion and adsorption on catalysts, selectivity of the naphthenic ring opening reaction is higher over Y catalyst than that over ZSM-5catalyst. The relative ratio of naphthenic ring opening reactions to dehydrogenation condensation reactions, abbreviated as s (NRO) /s (DHC), is higher over Y catalyst than that over ZSM-5 catalyst. At the weight hourly space velocity of 10 h-1, temperature of 475~550 ℃, catalyst/oil mass ratio of 3.0~9.0, reactions of bimolecular hydrogen transfer and dehydrogenation condensation became stronger, and selectivity of the products from naphthenic ring opening reactions decreases with the rising of temperature or catalyst/oil ratio over Y catalyst.
Abstract: Six adhesives were used to prepare ZSM-5 catalysts through kneading and extruding. The extruded ZSM-5 catalysts were characterized by SEM, NH3-TPD and N2 physical sorption and used in naphtha cracking. The results indicated that these ZSM-5 extrudants have no significant differences in their morphology and specific surface area, but have markedly more secondary pores compared with the original ZSM-5 sample. With pure silicon collosol as the adhesive, the resultant ZSM-5 extrudant exhibits lower acid amount, cumulative pore volume, micropore surface area and volume than the original ZSM-5 sample; however, the acid amount, surface area and cumulative pore volume of the extrudants obtained with aluminum-containing adhesives are almost identical to those of the original ZSM-5. For the naphtha cracking in a fixed bed reactor at 600 ℃, the yield of ethylene plus propylene over the extruded ZSM-5 catalyst with silicon collosol as additive is lower than that over the extrudants obtained with aluminum-containing adhesives.
Abstract: A series of HY-SBA-15(y) composite molecular sieves (y denotes the weight ratio of HY to SBA-15) were prepared by post-synthesis method and characterized by XRD, FT-IR, N2 sorption, and NH3-TPD. Ni-W/HY-SBA-15(0.10) catalyst was then prepared by impregnating HY-SBA-15(0.10) with Ni-W solution and used in hydrodearomatization of Maoming FCC diesel oil. The results indicated that HY-SBA-15 has both HY microporous and SBA-15 mesoporous structure and the microporous and mesoporous structures of HY-SBA-15 match remarkably well when the value of y is 0.10. Both Bronsted acid sites and Lewis acid sites are present on the surface of the composite molecular sieve HY-SBA-15(0.10) and its acidity is stronger than that of HY zeolite. When loading Ni and W on it, the Ni-W/HY-SBA-15(0.10) catalyst exhibits high activity in the hydrodearomatization and opening of aromatic rings.
Abstract: Silylated SiO2 with different hydrophobicities was prepared before the impregnation of cobalt precursor to obtain Co-based catalysts in Fischer-Tropsch synthesis. The effect of silylation on the crystallite structure and reduction behaviors of the resultant cobalt catalysts was investigated by FT-IR, 29Si CP MAS NMR, N2 sorption, XRD, Raman, XPS, and H2-TPR; their catalytic performance in Fischer-Tropsch synthesis was evaluated in a fixed-bed reactor under 2.0 MPa, 240 ℃, n(H2)/n(CO) ratio of 2, and space velocity (GHSV) of 1 000 h-1. The results indicated that compared with unsilylated SiO2, silylated SiO2 leads to larger and more perfect Co3O4 crystallite, weaker interaction between cobalt and silica, and higher reducibility; As a result, the activity of cobalt catalysts is enhanced and higher CO conversion is achieved for Fischer-Tropsch synthesis.
Abstract: CuO/ZnO/Al2O3 precursors were prepared by different precipitation manner; microwave irradiation was introduced in aging process. The effects of precipitation manner on composition of precursor, micro structure and performance of catalyst were characterized by means of XRD, DTG, H2-TPR. The reaction results indicated that the order of catalytic activity was Stepwise II ＞ Parallel-flow ＞ Stepwise I ＞ Reversed ＞ Forward. When Al(NO3)3 solution and Na2CO3 solution were precipitated first and then Cu(NO3)2-Zn(NO3)2 solution were precipitated with remaining Na2CO3, the prepared precursor contained more (Cu, Zn)5(CO3)2(OH)6, which possessed well-dispersed CuO, strong synergy in CuO-ZnO and low H2-reduction temperature after calcination.
Abstract: A commercial de-NOx catalyst for selective catalytic reaction (SCR) poisoned by K2O was regenerated with (NH4)2SO4 solution. The poisoning was simulated by loading different concentrations of K2O in the de-NOx catalysts through wet impregnation with KNO3 solution as the K2O precursor. After regeneration with (NH4)2SO4 solution, the poisoned catalysts exhibit effective activity under the simulated conditions of different space velocities and oxygen concentrations. The catalysts before and after regeneration were characterized by ion chromatogram (IC), nitrogen physical sorption, scanning electron microscope and energy dispersive atomic X-ray spectroscopy (SEM-Maps/EDX), and infrared spectroscopy (FT-IR). The results indicated that the regeneration process is effective to remove K2O from the poisoned catalysts and to restore the active sites of V=O, while the surface substances and mechanical properties of the regenerated catalysts are not significantly influenced by the regeneration.
Abstract: Four sorbents were prepared with CaO/MgO or CaO/Ca9Al6O18 that was produced from precursors of calcium D-gluconate monohydrate, magnesium D-gluconate hydrate and aluminum L-lactate hydrate with a simple wet mixing method. The effects of sorbent type, mass proportioning, SO2 concentration and calcination temperature on the adsorption capability of sorbent were studied. The results show that CaO/MgO( weight ratio 75%/25%)keeps the best CO2 capture capability, while CaO/CaO/Ca9Al6O18(weight ratio 75%/25%)keeps the best cyclic stability. The CO2 capture process is drastically affected by SO2. The CO2 capture capacity drops quickly when the SO2 concentration increases. However, the cumulative SO2 capture capacity increases at the same time. The total calcium utilization rises tenderly after many cycles, which becomes more obvious with increasing the SO2 concentration. The effect of calcination temperature on the adsorption characteristic of CaO/MgO and CaO/CaO/Ca9Al6O18 differs little.
Abstract: The effect of physicochemical properties of three fly ash samples on the mercury adsorption performance is investigated using a fixed-bed with a simulated gas by means of X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, laser particle size analyzer, scanning electron microscopy and other analytic methods. The results indicate that the mercury adsorption on the fly ash mainly proceeds in physisorption and chemisorption. Uncompleted burned carbon is an important factor for the improvement of mercury removal efficiency, and the C-M bond that is formed via the reaction between C and Ti, Si and other elements may promote the oxidation of mercury. Meanwhile, the inorganic compound such as Fe2O3 in the fly ash can also improve the oxidation of mercury. Higher specific surface areas, smaller pore diameter, and moderate particle diameter are all beneficial for the high mercury removal efficiency.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
