Abstract: A flash pyroprobe combined with GC-MS was used to investigate the effects of temperature on the release property of PAHs (polycyclic aromatic hydrocarbons) during pyrolysis of Pingshuo coal. The formation mechanism of PAHs was also discussed. The results indicate that the total amounts of the 16 PAHs released increase obviously with increasing temperature during pyrolysis, reach the maximum at 800℃, and then decrease. The ring distributions of PAHs have a notable dependence on the pyrolysis temperature. The different species of PAHs reaches the maximum yields at individual temperature. With increase in pyrolysis temperature, the total amount of PAHs increase observably, which is attributed to cracking of the bridge bonds, the fat side chain on aromatic ring, the methyl and phenolic group in the coal macrostructure. With further increase to 1 000 and 1 200℃, the amount of high-ring PAHs increases due to the occurrence of condensation reaction. Thermal cracking of macromolecular compounds concentrated during 600~800℃, and condensation are the main reactions occurred at high temperatures. The PAHs during coal pyrolysis are generated from the volatilization of aromatics structure in coal, the cracking reactions of macromolecular compounds and the condensation reactions of radicals at high temperature; meanwhile, the last one is the major source of high-ring PAHs during coal pyrolysis.
Abstract: X-ray photoelectron spectroscopy (XPS) was used to investigate the nitrogen and sulfur functional forms present in New Zealand coal (NXL) and its pyrolysis char prepared under argon atmosphere at 8 different temperatures between 300 and 1 000℃. The N 1s spectra obtained were curve-resolved into 4 peaks: pyridinic-N (398.8±0.4 eV), pyrrolic-N (400.2±0.3 eV), quaternary-N (401.4±0.3 eV) and nitrogen oxides (402.9±0.5 eV); and S 2p peaks into 6 peaks: pyrite (162.5±0.3 eV), sulphidic (163.3±0.4 eV), thiophenic (164.1±0.2 eV), sulfoxide (166.0±0.5 eV), sulfones (168.0±0.5 eV) and sulfate (169.5±0.5 eV). The results show that nitrogen present in coal in pyrrolic forms is converted into pyridinic functionalities upon heat treatment and nitrogen oxides disappeared above 900℃. The major organic sulfur form in NXL is thiophene and its content is over 50%. Pyrite is decomposed completely into troilite at 600℃.
Abstract: Based on the results of proximate analysis, elemental analysis, 13C-NMR, FT-IR and XPS results, the structure model of the raw coal in coal seam 11 of Wumuchang district, Yimin Basin of Hulun Buir, Inner Mongolia was built using ACD/lab software. The 13C-NMR predicting software ACD/CNMR predictor was used to modify the structure. The macromolecule structure model which coincides with the nuclear magnetic resonance map is achieved. The characteristics of structures of macromolecules are as follows. Benzene, naphthalene, anthracene and phenanthrene are aromatic constitutional units, the quantities are 1, 2, 2, 1 respectively. Ether linkages, hydrogen aromatic rings and ortho methylene are bridges connecting aromatic units. Oxygen atoms exist in forms of phenolic hydroxyl groups, the quantities are 7, 3, 2 respectively. Nitrogen atoms exist in forms of pyridine and pyrrole. Methyl and short fatty chains are distributed in the edges of aromatic rings. The coal structure is compared with lignite in nearby mining area and Shendong long flame coal with similar metamorphic grade. In the environment of high temperature and low pressure, oxygen containing functional groups are lost rapidly in the process of thermal revolution, leading to the formation of short chain aliphatic groups. The environment of low pressure during thermal revolution is benefit with escape of micro molecules, leading to the aggregation of free radicals, so that large aromatic structure units are formed. However, due to the steric effect caused by the linear chain aliphatic groups, the orientation arrangement of aromatic structure units is not favored, leading to the phenomenon that the maturation of chemical components occurs before that of coal structure.
Abstract: In the low-temperature fast pyrolysis of fructose to produce 5-hydroxymethyl furfural (HMF), furfural (FF) is formed as an important by-product. In this work, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were used to reveal the FF formation mechanism from low-temperature fast pyrolysis of fructose. It was found that both the yield and the relative content of FF increased with increasing pyrolysis temperature up to 350℃, but a further increase in the pyrolysis temperature led to a decrease of the FF. The largest peak area of FF reached as high as 11.6%. Four possible pathways are proposed for production of FF from fructose based on the density functional theory (DFT) calculations. The pathway 2 was found to be the optimal route. In this way, the fructose first underwent a six-membered ring (MR) transition state. Then, the C5-C6 bond broke with a simultaneous dehydration of the H of OH at C6 and the OH at C4 to give a dihydrofuran intermediate species containing C4=C5 double bond together with formaldehyde and water. This dihydrofuran intermediate species transformed to an enol intermediate upon a further dehydration of the OH at C2 and the H at C1 through a 4-MR transition state. Finally, the enol intermediate was transformed into FF through a 6-MR transition state and another dehydration process of the OH at C3 and the enol H at C1.
Abstract: Using softwood bark of Chinese fir and hardwood bark of eucalyptus as raw materials, the variation of their micro-crystal structures before and after pyrolysis was compared using X-ray diffraction. The components of bio-oils from 2 barks were analyzed contrastively with gas chromatograph-mass spectrometer and gel permeation chromatography. The results show that fiber structures and fatty chain structures in the bark are decomposed and destroyed. The main components of bio-oils, containing acids, ketones, phenols, alcohols, aldehydes, sugars and esters, are similar between the Chinese fir bark and eucalyptus bark, but the relative concentrations are different. On the contrary, the pyrolysis of eucalyptus bark produces more acids and ketones than Chinese fir bark, but phenols, alcohols and sugars are just the reverse. The phenols account for a large proportion of bio-oils, especially phenol and catechol. The molecular weight of bio-oils obtained from the bark is mainly concentrated from 300 to 500 g/mol; however, the relative concentration of eucalyptus bark (48.18%) is less than that of Chinese fir bark (61.14%).
Abstract: Pyrolysis of soybean oil was carried out in a ZnCl2-KCl molten salt. The effects of feed rate, flow rate of carrier gas, pyrolysis temperature and input quantity were studied. And the compositions of the bio-oil were analyzed by GC-MS. The results show that the feed rate and carrier gas flow rate have great influences on the pyrolysis by changing the reaction residence time of soybean oil. When the feed rate is 1.2 g/min and without the carrier gas, the soybean oil can be fully cracked with the longer residence time. The gasification of the primary pyrolysis products is enhanced with the increasing of temperature, which leads to the yield, the content of oxygenated compounds and the acid value of bio-oil increase. With the increasing of input quantity, the yield of bio-oil is near 70% and keeps stable, but the decarboxylation effect decreases. The properties of bio-oil are improved and its component distribution is similar to the 0# diesel after catalytic hydrogenation.
Abstract: Esterification of pyrolytic rubber seed oil with SO42-/ZrO2 soild acid as catalyst was investigated; the effects of zirconium sources, calcination time and temperature on the catalytic performance were considered. The acidic properties of the SO42-/ZrO2 catalyst were characterized by temperature-programmed desorption of ammonia (NH3-TPD) and pyridine adsorption infrared spectroscopy (Py-IR). The results indicated that the SO42-/ZrO2 solid acid prepared by using ZrOCl2 as zirconium source and calcined at 550℃ for 4 h exhibits high catalytic activity and stability in the esterification of the pyrolytic rubber seed oil. The esterification product obtained as a bio-oil was superior to those prepared via conventional methods; its properties are similar to those of 0# diesel oil.
Abstract: The XANES spectrum is employed to study the sulfur functional groups in asphaltenes. Since the asphaltenes are complicated mixture, it is difficult to distinguish different classes of sulfur compounds in asphaltenes. Therefore, the higher order derivative spectra of sulfur XANES were introduced in order to improve sulfur XANES resolution and to qualitatively analysis sulfur functional groups in asphaltenes. Sulfur XANES spectra were deconvoluted by using of several Gaussian and arctangent functions to quantify the sulfur species. In order to convert peak area percentages to atomic percentages, the relative 1s→3p transition probabilities of different sulfur classes must be considered. The areas of the different Gaussian peaks were calculated and revised for their oxidation state-dependent absorption cross-section. The contribution of sulfur species to total sulfur was calculated by the corrected peak areas. The result showed that sulfur species in asphaltenes of atmospheric and vacuum residue were mainly in form of thiophene, sulfoxide, thiophene sulfone and sulfate, while hardly contained sulfide.
Abstract: Laboratory experiments and reaction kinetics analysis were conducted to reveal the mechanisms of low temperature oxidation (LTO) reaction of crude oil and oil components in the temperature range from 70 to 120℃. SARA(saturates, aromatics, resins, and asphaltenes)analysis was conducted to study the variations of different oil components before and after LTO reaction. The experiments using pure oil components (i.e. n-hexadecane, wax, anthracene and asphaltenes) were preformed to investigate the oxidation activity of different oil components. At low temperatures (70~90℃), light oil compounds (n-hexadecane and anthracene) can be more resistible to the oxidation than heavy asphaltenes and wax. The activation energies of the various components LTO reactions calculated based on the experimental results show that the heavy components, having a relative low activation energy, can be more easily subjected to low temperature oxidation than the light HC components. Heavy oil exhibits a higher oxidation activity than light oils in the LTO reaction, which also means that the heavy oil components is more easily oxidized at low temperatures. The experimental results can provide a basis for the air injection process design in oilfields.
Abstract: Two Al2O3 supports were characterized by means of NH3-TPD, FT-IR and N2 adsorption-desorption. The characterization results showed that the two Al2O3 supports have no significant differences in their total acidity and acidity strength. The acid sites are mainly Lewis ones, but Al2O3 (b) has larger average pore diameter and pore volume than Al2O3 (a). The influence of the pore structures of the Al2O3 supports on the full range FCC gasoline upgrading performance of the nanosized HZSM-5 based catalysts was investigated in a fixed-bed reactor. The results indicated that the HZSM-5 catalyst extruded with macroporous Al2O3 exhibited superior activity, stability and performance in reducing olefin content of FCC gasoline. The modified nanosized LaNiMo/HZSM-5 catalyst reduced olefin and sulfur concentration in FCC gasoline by about 83% and 87% within 300 h time on stream, respectively, meanwhile the gasoline octane number was preserved.
Abstract: The effects of in-situ hydrothermal treatment on the ZSM-5 zeolite were studied, and its performance for syngas to gasoline via DME reaction process was dicussed using two-stage equal-pressure reactor system. The texture, surface acidity and catalytic performance of the treated ZSM-5 zeolite at different temperatures were investigated. Physicochemical properties of the zeolite were characterized by XRD, XRF, BET, NH3-TPD and TPO. The results indicated that most of Al was removed from the nonframework of zeolite through appropriate hydrothermal treatment at 400℃. A decrease in the amount of acidic sites and an increase of specific surface area were observed, and accordingly, the catalytic activity of the ZSM-5 zeolite and product selectivity were improved significantly.
Abstract: A series of potassium modified Fe-Mn catalysts were prepared by hydrothermal method and applied to the catalytic synthesis of light olefins from CO hydrogenation. The catalyst samples were characterized by SEM, TEM, XRD, H2-TPR and FT-IR techniques. Results showed that the prepared sample particles were spherical with 50~70 nm size and the carbonyl and hydroxy groups were observed on their surfaces. The bulk composition was mainly Fe3O4 before the reaction. Fe5C2 and MnCO3 were formed after the reaction. The prepared samples showed high activity and olefin selectivity under the given reaction conditions. Using the sample S3 (Fe:Mn:C6:K=3:1:5:0.10), the CO conversion and the olefin productivity reached 95.02% and 62.86 g/m3 (H2+CO), respectively. Compared with the catalyst prepared with co-precipitation method, the S3 catalyst had lower CH4 selectivity(13.88%) and CO2 selectivity(13.98%).
Abstract: Ammonia was added to the ion-exchange solution to adjust the pH in the preparation of CuNaY catalyst by ion-exchange of NaY zeolite with Cu2+ aqueous solution, and then the ion-exchanged CuNaY was activated by high temperature calcinations. The effect of anion type in the Cu2+ aqueous solution on the ion-exchange process and catalytic performance of the catalyst were studied, it is shown that the catalytic activity of CuNaY ion-exchanged of NaY with aqueous solution of copper salts was low, when the pH of ion-exchange solution was adjusted to 11 by adding ammonia, the catalytic activity and selectivity of DMC increased greatly. Based on the characterization of the microstructure of the catalyst by elementary analysis, XRD, XPS and H2-TPR techniqs, it is shown that by adding ammonia into the ion-exchange solution, the ion-exchanged reaction is promoted, resulting in the increase of the ion-exchanged Cu2+, 75% of the Cu2+ in the catalyst located in the supercages of the Y zeolite.
Abstract: The Pd-P/C catalyst with the high content of P0 was successfully prepared with the organic impregnation-reduction method. Pd-P/C catalysts with different Pd/P atomic ratios were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray Spectrometer (EDX). The effect of Pd-P/C catalysts with different Pd/P atomic ratios on the oxidation of formic acid was also demonstrated by several electrochemical measures. It was found that the potential of the anodic peak of formic acid at catalyst electrodes increased in the order of Pd1P6/C < Pd1P8/C < Pd/C, and the electrochemical stability of three electrodes was in the order of Pd1P6/C > Pd1P8/C > Pd/C. The Pd1P6 catalyst showed the best performance for the oxidation of formic acid. The Pd-P/C catalysts with the suitable atomic ratio of Pd and P had higher activity and stability for the oxidation of formic acid.
Abstract: Nano-ZnO sorbents synthesized by a homogeneous precipitation method were characterized by BET (Brunauer-Emmett-Teller), XRD (X-ray diffraction) as well as XPS (X-ray photoelectron spectroscopy) analysis. The adsorption of elemental mercury by nano-ZnO under nitrogen and simulated gas atmosphere was studied on a bench-scale fixed-bed apparatus. The effect of various gases on Hg0 removal performance by nano-ZnO was analyzed. The results show that the mercury removal efficiency of the nano-ZnO is relatively poor in nitrogen atmosphere. The presence of H2S promotes the Hg0 removal by nano-ZnO observably and the mercury removal efficiency can be maintained for a long time even after stopping pass into H2S. The presence of CO and H2 promotes the Hg0 removal because of desulfurization effect of nano-ZnO. As the temperature increases, the formation of elemental sulfur in the surface of the nano-ZnO decreases, which can suppress the removal of Hg0 by sorbent.
Abstract: The performance of simultaneous desulfurization and denitration during coal combustion in O2/CO2 atmosphere with premixed and injected limestone modified by wood vinegar (LMWV) was investigated in a tube furnace and a drop tube furnace, respectively. The SO2 and NO reduction efficiency are 91.0%~94.9% and 23.5%~30.8% respectively during the combustion of coal premixed with LMWV at 1 173 ~ 1 323 K at the Ca/S molar ratio of 2.0. The desulfurization and denitration rates increase with raising the Ca/S molar ratio, and the optimum Ca/S molar ratio is from 1.5 to 2.0. The higher the sulfur content of coal, the greater desulfurization and denitration rates are gained during coal combustion. The performance of desulfurization and denitration with LMWV is better than that with calcium acetate. The maximum desulfurization and denitration rates of 75.8% and 86.6% respectively are gained by injecting LMWV directly into the flue gas of O2/CO2 coal combustion at both 1 223 K and 1 323 K and the Ca/S molar ratio of 2.0 with a residence time of 0.8 s. When the ammonia is injected into the reactive zone at [NH3]/[NO] molar ratio of 0.75, the desulfurization rates are 73.2% and 63.9%, and the denitration rates are 93.2% and 94.8%, respectively at the combustion temperature of 1 223 K and 1 323 K.
Abstract: A series of Fe2O3/Al2O3 oxygen carriers with different Fe2O3 loading were prepared by different methods and characterized by means of XRD, H2-TPR, CH4-TPR, O2-TPD and BET technologies. The effects of the preparation methods on the Fe2O3/Al2O3 oxygen carrier structure, activity and the selectivity for CO2 were also investigated. An obvious effect of Fe2O3 loading on the reactivity for methane oxidation and the CO2 selectivity is observed. Lower Fe2O3 loading results in a lower reactivity of oxygen carrier and more CO content in the product gas. The reactivity of Fe2O3/Al2O3 is also affected by the preparation method of oxygen carrier. The Fe2O3/Al2O3 oxygen carrier with a Fe2O3 loading of 60% (mass ratio) has the best activity and redox stability for methane oxidation. Methane can be quickly converted to CO2 and H2O with higher selectivity at 850℃ for 15 min. After redox cycling in alternant methane/air atmosphere for 30 times, no decline in the conversion of methane and the formation of CO2 is observed.
Abstract: NO reduction by methane on the surface of iron and iron oxides was experimentally investigated in a one-dimensional temperature-programmed ceramic tubular reactor at 300~1 100℃ in both nitrogen and simulated flue gas atmospheres. To ensure that the residual methane after NO reduction and the intermediates (e.g. CO) formed during the NO reduction were completely burned out, a second furnace with a supply of O2 was connected in series after the first furnace. The results indicated that methane can effectively reduce NO to N2 over the surface of metallic iron and iron oxides. In N2 atmosphere, more than 95% of NO is reduced by methane over metallic iron at a temperature above 900℃, which is very close to that for NO reduction over iron oxides. In the simulated flue gas atmosphere with an excessive air ratio being lower than 1.0, more than 90% of NO is reduced by methane over both metallic iron and iron oxides at a temperature above 900℃; there is little difference in NO reduction under both burnout or non-burnout conditions. NO is reduced simultaneously via two routes, i.e. the direct reduction by metallic iron and the reduction by reburning of methane. Iron oxides are reduced to metallic iron by methane through partial oxidation over iron oxides to maintain the sustainable reduction of NO by metallic iron. At the same time, the intermediate products during NO reduction by methane such as HCN/NH3 are converted by iron oxides, which prevent the NO reduction efficiency from dropping after burnout. The present results then prove that methane can effectively reduce NO over iron or iron oxides under fuel rich condition.
Abstract: A series of Pt-Pd/CeO2 catalysts with different Pt/Pd ratios were synthesized by impregnation method; their catalytic activity and sulfur resistance in the oxidation of diesel exhaust were investigated. The results showed that Pt-Pd synergy is able to reduce the ignition temperature and broaden the active window of Pt-Pd/CeO2 catalysts for the oxidation of diesel exhaust. The ratio of Pt/Pd has a great effect on catalytic performance; The Pt0.2Pd0.8/CeO2 catalyst shows the highest activity in the oxidation of simulated diesel exhaust containing C3H6, CO and NO. H2-TPR results suggest that the amount of surface active oxygen increases with the Pt/Pd ratio, which is also well related to the sulfur resistance of the Pt-Pd/CeO2 catalysts; higher Pt/Pd ratio is of benefit to the oxidation of diesel exhaust in the presence of SO2, as the active sites of PtO2 and PdO are easily covered by sulfate.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
