Abstract: This paper was to examine the changes in structure and reactivity of chars upon to varied cooling approaches for "hot" char derived from Shengli brown coal. The "hot" chars prepared from the pyrolysis of brown coal remained in argon for 30 min in a newly-designed two-stage quartz reactor at 400, 600 or 800 ℃, respectively. Subsequently, the "hot" chars were used to prepare the "cold" char by cooling at room temperature, dry ice and liquid nitrogen. The "cold" chars were then employed to the ex-situ gasification in 15% steam atmosphere at 900 ℃ for 10 min. For comparison, the in-situ gasification of "hot" char derived from the same pyrolysis without cooling was conducted by changing the reaction atmosphere from argon to 15% steam (under the same condition as the ex-situ gasification). Reactivity and physical-chemical structure of chars were characterized by TGA, SEM, BET and Raman spectroscope, respectively. Results showed that the yield of "hot" char in-situ gasification was lower than that of the "cold" char ex-situ gasification. Cooling approaches had the obvious influences on the porous structure of subsequent char. The specific surface areas and porous volumes were reduced dramatically with increasing quenching rate, but there was no significant effect on the chemical structure of char (such as aromatic ring systems and O-containing functional groups). In addition, the reactivity of "cold" chars was decreased with increasing cooling rate. The irreversible destroy of char structure, caused by the cooling treatment, contributed to the decrease of gasification reactivity of chars.
Abstract: Flash pyrolysis characteristics of four Chinese coals were studied in a Curie-pointed reactor and gas chromatography (Py-GC) combined system. The yield of volatile matter (VM) and evolution of gaseous VM components were measured. It is found that ≥ 50% of VM is released at the early stage (t ≤ 2 s) of flash pyrolysis. It needs ~10 s to totally devolatilize 1 mg coal in the Curie-point reactor with the sample wrapped in a ferromagnetic foil. The yields of gaseous VM component are in the order of H2 > CH4 > CO > CO2 > C2(C2H6, C2H4) > C3 (C3H8, C3H6). The yield of VM increases as the pyrolysis temperature increases. Under the same pyrolysis condition, high VM content coals released more VM than the low VM content ones. Yields of H2 and CH4 increase greatly with the pyrolysis temperature. Yields of CO and CO2 depend on both the content of oxygen in the coal and pyrolysis temperature. Amounts of C2 and C3 gases are relatively much less than the others, accounting for less than 5% in volume in the gaseous VM.
Abstract: The alkali metal transformation during high-sodium Zhundong coal pyrolysis was investigated in a vertical tubular furnace reactor. The release characteristics, modes of occurrence of Na, the microstructure of char samples after pyrolysis at different temperatures were examined by using inductive coupled plasma equipped with atomic emission spectrometer(ICP-AES), X-ray diffractometry (XRD) and scanning electron microscopy with an energy dispersive X-ray spectrometer(SEM-EDX), respectively. Meanwhile, the release forms of alkali metal from coal were simulated by Fact sage 6.1. The results show that a part of sodium in high-sodium coal is released during pyrolysis, starting to release at 600 ℃ and reaching to 40.2% of release at 900 ℃. It is concluded that Na in the coal is released as NaCl, and no molten matter is found when the pyrolysis temperature is below 900 ℃.
Abstract: Na2CO3 was added into coal ash with the amount of 20% which was converted into the weight of Na2O. Then the mixed coal ash samples were sintered under different temperatures. To explore the transition mechanism of sodium compounds in the sintering process, the EDS elemental analysis method and XRD phase analysis method were used to analyze the sintered ash samples. Then chemical thermodynamic equilibrium calculations were carried out on the basis of EDS analysis results with the Equilib module of the Fact sage 5.2 software. And the results were compared with those of the experiment. Results show that sulfur enrichment will occur as the elevating of temperature. Sodium mainly reacts with sulfur to compose Na2SO4. At the same time NaCl occurs, and it will react with the potassium compounds to generate KCl. NaCl, KCl and Na2SO4 react with other substances to produce low temperature eutectics.
Abstract: The existence form of minerals in Wucaiwan(WCW) coal were studied by extraction, XRD, SEM-EDX and ICP-OES. The influences of different forms of mineral on the combustion characteristics and the fusibility of ash were evaluated. The results indicate that the original minerals in WCW coal mainly include calcite, anhydrite, kaolinite, quartz and pyrite. The modes of occurrence of sodium in WCW coal are mainly in the form of water-soluble sodium. The organic bound sodium, magnesium and calcium can promote the combustion of coal to a certain extent. The fusibility of WCW coal ash is mainly influenced by the mol ratio of iron to calcium. The ash melting points decreases with increasing the Fe2O3/CaO mol ratio.
Abstract: Different rice husk samples and their components (cellulose, hemicellulose and lignin) were investigated with emphasis on the influence of potassium on their pyrolysis behaviors by using thermogravimetric (TG) analysis. The results indicate that the maximum weight loss rate of cellulose decreases with the addition of KCl. However, no significant differences are observed for the pyrolysis behavior of hemicellulose and lignin. The TG/DTG curve of a model rice husk (a mixture of cellulose, hemicellulose and lignin) could be obtained by superposition of that for each component. However, during pyrolysis the raw stable structure of basic components in the rice husk results in a change from a sharp peak for the model rice husk to a shoulder peak for the AW rice husk (pretreated with HCl to remove K and the other mineral matters) at around 300 ℃. In addition, the effect of KCl addition on pyrolysis of the AW rice husks was also studied. The results show that potassium has a remarkable catalytic effect on pyrolysis of the rice husk samples. The pyrolysis characteristics vary depending on the addition methods of KCl. While char yields decrease with the addition of KCl using mechanical method (except for the cellulose), the char yield and the maximum weight loss rate of impregnated AW rice husk increase gradually with the increase of KCl content.
Abstract: Pyrolysis characteristic of enzymatic/mild acidolysis lignin (EMAL) from moso bamboo was investigated using fast pyrolysis technology coupled with gas chromatography/mass spectrometry (Py-GC/MS). Pyrolysis mechanism and formation and distribution of pyrolysis products were studied. Pyrolysis temperature, as a vital factor, affects on lignin pyrolysis including its products and reaction pathway. The results show that pyrolysis products derived from EMAL pyrolysis are mainly heterocyclic (2, 3-dihydrobenzofuran), phenols, esters, and a few amount of acetic acid. Pyrolysis temperature has a distinct impact on the amount of pyrolysis products. At low temperature range (250~400 ℃), pyrolysis products are almost 2, 3-dihydrobenzofuran and its highest content is 66.26% at 320 ℃. At high temperature range (400~800 ℃), a most of pyrolysis products are phenols reaching the highest level of 62.58% at 600 ℃, and a few amount of acetic acid only occurs at 800 ℃.
Abstract: Long-chain alkanes fuel were produced from lignin deploymerization model compounds by introducing small intermediate molecules through Friedel-Crafts alkylation and subsequent hydrogenation. The effect of catalyst, small intermediate molecules, temperature, reaction time, feed mixture ratio, and raw materials on the conversion of the lignin phenolic monomers to dimmers was investigated; after that, the C13~19 alkanes fuel was obtained by hydrogenating the lignin phenolic dimers. The results showed that over Amberlyst-15 catalyst, with a n(guaiacol)/n(small intermediate molecules) ratio of 15:3, after reaction under 100 ℃ for 24 h, the yield of lignin phenolic dimers products reaches 68%; the lignin phenolic dimers can be further converted to alkanes completely through hydrogenation. Such a route for producing long-chain fuel may provide a new alternative for the utilization of lignin.
Abstract: The epoxidized biodiesel (EBD) was prepared with biodiesel (BD) as raw material, which was then subjected an etherification ring opening reaction with 2-ethyl hexanol over the D001 resin catalyst; the resultant product can be used as the lubricant base stock. The products and material used were characterized by FT-IR and TG; the properties of as synthesized lubricant base stock were compared with those of EBD and the lubricant from 150SN mineral oil. The results showed that the as-synthesized lubricant base stock is excellent in terms of thermal stability, viscosity-temperature behavior, viscosity index, oxidation stability, and wear resistance and loading capacity. Moreover, D001 resin as a catalyst exhibits good reusability; it remains high active after being used for five times.
Abstract: A new Brønsted basic dicationic morpholine ionic liquid (IL) was synthesized with N-methyl morpholine and 1,4-dibromobutane via a two-step procedure. The structure of new dicationic IL was characterized by FT-IR, 1H NMR spectra and elemental analysis and the thermal stability was analyzed by TGA. Meanwhile, the alkalinity and solubility of the dicationic IL were measured and its catalytic activity in the transesterification of soybean with methanol to produce biodiesel was investigated. The results show that under the optimized conditions of n(methanol)/n(soybean oil) = 14, catalyst amount of 5% based on soybean oil, 60 ℃ and 5 h, the yield of biodiesel reaches 95.6%. After recycled by drying under vacuum, the dicationic IL can be reused for more than 6 times without significant decrease in the catalytic activity.
Abstract: Solvent evaporation self-assembly method was adopted to synthesize CuO/γ-Al2O3 composite catalysts with mesoporous structure using F127 as template, aluminum isopropoxide and copper nitrate as precursor. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), H2 temperature program reduction (H2-TPR), nitrogen adsorption-desorption and transmission electron microscope (TEM) were used to characterize the properties of the catalysts. The results show that ordered and uniform mesoporous structure as well as large specific surface area were discovered in catalysts with different copper contents. In the syngas to dimethyl ether (DME) reaction, the highest conversion of CO reached 68.8% and the selectivity of DME achieved 59.0% under space velocity of 1 500 h-1, 320 ℃ and 5 MPa. The conversion of CO decreased from 68.8% to 59.5% after 50 h on stream, and the selectivity of DME kept constant. The partial loss of activity was due to the aggregation of copper on this catalyst.
Abstract: Mo-Ni/Al2O3 catalysts were modified with phosphorus by using the impregnation method. By changing the addition sequence of phosphorus, three types of catalysts, viz. MoP-Ni/Al2O3, Mo-NiP/Al2O3 and Mo-Ni/PAl2O3, were obtained with a P loading of 1.34%. These catalysts were characterized by X-ray diffraction, temperature-programmed desorption of NH3, temperature-programmed reduction by H2 and N2 sorption experiment. The catalytic properties of these catalysts were investigated with the hydrodenitrogenation (HDN) of low- and middle-temperature coal tar obtained from Xinjiang province. It was shown that appropriate P addition sequence can alter acid site distributions, increase the proportion of effective pores between 10 and 13 nm, weaken the interaction of the support and active metal components and make the reduction of the active components easier, consequently, improving the catalytic performance. The HDN activity of the three types of catalysts decreased in the order of Mo-Ni/PAl2O3(74.36%) > Mo-NiP/Al2O3(72.74%) > Mo-Ni/Al2O3(56.13%) > MoP-Ni/Al2O3(71.72%).
Abstract: NixCo1-xCoAlO4 spinel oxides with different compositions were prepared by sol-gel method and further modified with K2CO3 by incipient impregnation. The NixCo1-xCoAlO4 spinel oxides were characterized by means of nitrogen physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and temperature-programmed reduction by hydrogen (H2-TPR); the effect of preparation parameters such as composition, mother liquid pH value, and potassium loading on their catalytic activity in N2O decomposition was investigated. The results show that the K/Ni0.15Co0.85CoAlO4 catalyst prepared with a pH value of 3 and a K/(Ni+Co) molar ratio of 0.1 is most active for N2O decomposition; over it, N2O can be completely decomposed into nitrogen and oxygen at 450 ℃ in the presence of oxygen. K-modified catalysts exhibit high catalytic activity, good reducibility and resistance towards water, as K species may be able to weaken the surface metal-oxygen bonds.
Abstract: The experiment on simultaneous removal of NOx and SO2 from glass furnace flue gas by ozone oxidation and spray tower was carried out. The experimental results show that the concentration of the sodium hydroxide as the spray solution has less effect on NOx removal efficiency when pH is above 10, but SO2 in the flue gas greatly enhances the NOx removal. The NOx removal efficiency reaches 70% and the SO2 removal efficiency remains above 99% as the concentration of sodium hydroxide (NaOH) is 0.5% and the O3/NO mol ratio is 1.6. When sodium sulfide (Na2S) is added into the spray solution, the NOx removal efficiency is improved and increases with the concentration of Na2S. During this process, SO2 has no obvious influence on the NOx removal; the NOx removal efficiency reaches 70% and the SO2 removal efficiency remains above 95% as the concentration of NaOH and Na2S is 0.5% and 0.6%, respectively, and the O3/NO mol ratio is 1.2. Long-running experiments (60 min) indicate that NO is transformed into NO2- in the solution and the NOx removal efficiency does not change with the pH value of the spray solution.
Abstract: The TiO2 photocatalyst loaded with 1% Pt, Pd, Au, Ag have been prepared by photo deposition method. The catalysts are characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis spectrometer. The electro-catalytic performance for hydrogen production and photo electrochemical performance are investigated by using linear sweep voltammetry method and continuous transient current-time response method. The performance of photocatalytic CO2 reduction on TiO2 loaded with different noble metals are discussed. The results show that loading noble metal on TiO2 can significantly accelerate the separation of photo production electron and hole and reduce the recombination rate. Furthermore, the sequence of cocatalysts selective reduction for CO2 is Ag>Au>Pd>Pt. A negative correlation between the selectivity of CO2 hydrogenation and hydrogen production has been discovered. The cocatalyst which has advantage to hydrogen evolution process goes against the selectivity of CO2 hydrogenation.
Abstract: The effects of coexistent gaseous components and fine particles on the CO2 separation performance by polydimethylsiloxane/polysulfon (PDMS-PSF) flat sheet composite membranes were investigated in a simulated test-bed. It can be found that O2 slightly inhibits the CO2 separation performance, while the effect of SO2 is negligible during the test time due to its low concentration in the flue gas. Water vapor promotes the CO2 separation performance of PDMS-PSF composite membranes. The fly ash fine particles significantly deteriorate the CO2 separation performance of PDMS-PSF membranes. Moreover, the CO2 separation experiments by PDMS-PSF membranes with an actual flue gas from a desulfurization system of the coal-fired hot testing facility were conducted for 50 h. At the beginning, the CO2 separation performance is slightly improved due to the combined effect of water vapor, O2 and SO2. With the extension of the test time, the impact of the fine particles deposited on the membrane surface increases, which gradually deteriorates the CO2 separation performance of PDMS-PSF membrane. The CO2/N2 selectivity and the CO2 permeation rate are decreased by 17.91% and 28.21%, respectively.
Abstract: A novel tetraethylenepentamine (TEPA) modified mesoporous silica gel (SG) sorbent (TEPA-SG) for CO2 capture was prepared by the wet impregnation method. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), and N2 adsorption-desorption technologies. Meanwhile, the effects of TEPA loadings and adsorption temperatures on the adsorption capacity were investigated in a self-assembled fixed bed reactor. Different weight percentages of polyethylene glycol (PEG) were added to TEPA-SG to study the promoting effect of hydroxyl groups on the adsorption capacity and regenerability. The results show that the SG modified by 40% TEPA has a maximum adsorption capacity of 2.21 mmol/g at 70 ℃ and atmospheric pressure. Moreover, the adsorption capacity increases to 2.70 mmol/g by adding a desirable amount of PEG, and after ten cyclic adsorption-desorption tests, the adsorption capacity is maintained at 2.66 mmol/g, demonstrating that as-prepared TEPA and PEG modified sorbent displays an excellent regenerability. In addition, the isosteric heat of adsorption based on the Clasius-Clapeyron equation approaches 30~40 kJ/mol, and decreases gradually with increasing the adsorption capacity, indicating that the surface of TEPA30/PEG10-SG sorbent shows an energetic heterogeneity.
Abstract: NaY-C and NaY-P adsorbents were successfully obtained through modifying parent NaY zeolite with citric acid and phosphate acid, respectively. The obtained adsorbents were characterized by scanning electron microscope, X-ray diffraction, X-ray fluorescence, N2 sorption and temperature programmed desorption of NH3. The mesopore surface area of the NaY-C adsorbent was increased when the parent NaY zeolite was modified by citric acid, with preserving he zeolite skeletal structure. Meanwhile, the decreased weak acid and increased strong acid content were observed in NaY zeolite modified with phosphate acid aqueous solution and the amount of strong acid sites in the NaY-P adsorbent was more than in the NaY-C adsorbent. The adsorption desulfurization results showed that the NaY-C adsorbent exhibited much higher desulfurization activity than the NaY-P adsorbent in the No.0 diesel oil, although all benzothiophene in model diesel was removed over both. In regeneration experiment, the benzothiophene removal of model diesel oil decreased from 100% to 91.97% and 85.96% after six regenerations over NaY-C and NaY-P adsorbents, respectively. Therefore, the NaY-C adsorbent possessed better desulfurization performance, possibly because the mesopore of the adsorbent is beneficial to the adsorption desulfurization.
Abstract: CuO/Al2O3-MgO catalyst was prepared by ultrasound assisted dispersion and used in the catalytic combustion of lean methane. The CuO/Al2O3-MgO catalyst was characterized by SEM, XRD, XPS, and H2-TPR and the effect of ultrasonic modification on the structure and catalytic performance was investigated. The results showed that the activity of the CuO/Al2O3-MgO catalyst prepared by ultrasonic treatment is much higher than that prepared by the conventional impregnation method. The catalytic activity of CuO/Al2O3-MgO is related to both the ultrasonic time and power; the optimum ultrasonic time and power are 20 min and 150 W, respectively. Compared with the conventional impregnation, the ultrasonic modification is propitious to get a catalyst with higher surface area and pore volume, smaller particles, and higher dispersion of active Cu species. Moreover, the ultrasonic modification may promote the formation of Cu+ on the catalyst surface and improve the low temperature reducibility. All these can depress the activation energy and enhance the activity of the CuO/Al2O3-MgO catalyst in methane oxidation.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
