Abstract: The kinetics of decomposition of hydrogen bonds in a Chinese lignite was studied using a new method of in-situ diffuse reflectance FT-IR （DRIFT） with pulverized coal samples directly. In addition, a new experimental technique in DRIFT measurement to avoid the condensation of volatile matter at high temperatures was introduced and used in this work. Based on two hypotheses, the single reaction model is used to caculate kinetic parameters for decomposition of hydrogen bonds （except OH－π） in coal heated up to 560℃. The results show that the decomposition of carboxylic acid dimers, OH－N and SH－N follows the second order reaction, while the decomposition of OH－OR2, tightly bound hydroxyl tetramers and self-associated hydroxyls follows the first order reaction. The calculated activation energies of some hydrogen bonds agree well with those obtained with other methods in references. Among the six types of hydrogen bonds studied, the decomposition of carboxylic acid dimers, OH－N, SH－N and tightly bound hydroxyl tetramers can be divided into two stages （230℃~380℃ and 380℃~500℃）, while that of OH－OR2 and self-associated hydroxyl groups can be treated as only one stage. Moreover, the mechanism of the decomposition of tightly bound hydrogen bond was suggested based on the comparison of decomposition activation energy of self-associated OH with its bond strength in references.
Abstract: The volatility and mobility of eleven trace elements （Hg, As, Se, Pb, Cr, Cd, Mo, Ni, Co, U and Th） in coal from Shizuishan Power Plant were investigated. Column leaching tests on bottom ash and fly ash by sulfuric acid for 60h were conducted. The contents of trace elements in input coal, bottom ash, fly ash and leaching solutions were determined by inductively coupled plasma mass spectrometry （ICP-MS） and atomic fluorescence spectroscopy （AFS）. The volatility of trace elements during coal combustion was calculated based on the trace elements concentration in coal, ash and the ash yield of the raw coal. The results demonstrate that over 50% of As, Pb, and Hg volatilize to the atmosphere. Leaching test results indicate that the maximum leaching proportion of As, Cd, Ni, and Mo is 1.8%~6.2%. Based on the volatility and leaching characteristics, the volatilization and migration model of trace elements in the process of combustion and leaching was established. The results show that volatility of trace elements is the main pollution sources on environment in Shizuishan Power Plant. The concentration of Pb, Cd, Mo, Co, Ni, and Cr in leachate is extremely high and they are potential harmful elements to the environment.
Abstract: The concentration, distribution occurrence modes of gold and mechanism of its accumulation in No.17 coal seam of Pu'an coalfield, Guizhou Province were studied using neutron-activation method (INAA), scanning electron microscope with an energy-dispersive X-ray (SEM-EDX) and electron probe analysis (EMPA). The results show that the content of gold in the No.17 coal seam is 2.61×10-9～9.73×10-9, with the mean value (6.29×10-9) higher than that in coals from China and the world. The gold in coal mainly exists in form of inorganic mineral. The carrier minerals are pyrite and clay. The source of gold is epigenetic hydrothermal, which can be captured by the loose and porous coal seam. In addition, closed hallow sea environment provides favorable conditions for gold accumulation. Deep fault-hydrothermal process is the mainly type of gold accumulation in the No.17 coal seam.
Abstract: The geochemical behavior of 59 constant and trace elements in brown coal of ZK0407 well located at Honghaigou area in Yili basin of Xinjiang, China, was examined by mathematical statistics methods. It is showed that the elements in ash is opposite number with those in inherent moisture and in fixed carbon, and has synchronous changes with those in volatile matter. ZK0407 well has been located at interlayer oxidation zones and was uranium bonanza in geological history. Now, it is the wing of mineralization under interlayer oxidation zone. Uranium maybe mainly exist in the pore of brown coal and clay fraction in coal by manner of physical adsorption.
Abstract: Using acetic acid (AC), acrylic acid (AR), acetyl acetone (AA), furfural, 2-methoxy phenol (MP) and water as representative compounds and p-toluene sulfonic acid as catalyst, the esterification upgrading was examined in supercritical methanol and under atmosphere pressure. The comparison results of esterification and simultaneous esterification of AC and AR as well as the effect of water show that supercritical esterification is superior to normal liquid-phase esterification in view of acid removal. Furthermore, transesterification reaction could take place when simultaneously esterifying mixed acids in supercritical methanol, leading to relatively higher conversion for the acid like AR which hardly reacts with methanol at normal condition. The reason for low acid conversion in the presence of water is attributed to the retarding effect of water on esterification, rather than a result of equilibrium shifting, since water tends to weaken the electrophilicity of positive carbonyl ion. However, such effect in supercritical methanol is much insignificant because supercritical reaction not only carries out at higher reaction temperature and consequently accelerates the reaction rate, but also provides a weaker hydrogen bond circumstance. Although AA and furfural have unnoticeable effect on the esterification of organic acids, AA itself can be converted into acetone and methyl acetate via a pyrohydrolysis and esterification mechanism. Acetalization reaction of aldehyde with methanol can occur when furfural is present in the esterification. It is found that phenols such as MP can obviously promote the esterification of AR with methanol and inhibit its polymerization, as a result, enhancing the conversion and selectivity of esterification reaction.
Abstract: Phosphorus promoted presulfided NiMo/Al2O3 catalysts were prepared by successive incipient wetness impregnation and characterized by XRD, N2-physisorption, TPR and HRTEM. The effect of phosphorus on the hydrodesulfurization (HDS) hydrodenitrogenation (HDN) performance of the presulfided NiMo/Al2O3 catalyst was investigated. The results indicate that the main active phase is type II MoS2 or Ni-Mo-S phase because of their weak interaction with the support. The incorporation of phosphorus in the catalyst enhances the dispersion of MoS2 particles by increasing the stacking number and reducing the slab length. Phosphorus has no influence on the metal-sulfur bonding energies in the Ni-Mo-S phases and bulk MoS2, but it increases the proportion of Ni-Mo-S phases in the metal sulfides. NiMoP-1.2 catalyst (containing 1.2% phosphorus) exhibits high hydrogenation (HYD) selectivity in the HDS of dibenzothiophene (DBT) and high HDN ratio of quinoline, which can be attributed to its high dispersion of the active phase. The HYD activity in HDS and HDN ratio on NiMoP-1.8 catalyst with excess phosphorus (1.8%) is declined due to the aggregation of MoS2 particles and the decrease of the catalyst surface area.
Abstract: Hydrodenitrogenation of indole and 1,2-dihydroindole were performed over a NiWS/γ-Al2O3 catalyst in a continuous fixed-bed microreactor; the effects of H2S, quinoline and its hydrodenitrogenation intermediates on the hydrodenitrogenation of indole were investigated. Compared with indole, 1,2-dihydroindole exhibits obvious self-inhibition effect on the hydrodenitrogenation. H2S can promote C(sp3)-N bond cleavage in 1,2-dihydroindole and slightly inhibit the hydrogenation reaction and C(sp2)-N bond cleavage in o-ethylaniline due to the competitive adsorption these species. The conversion of indole and denitrogenation efficiency are decreased seriously by adding quinoline into indole, indicating that quinoline inhibits the hydrogenation reaction pathway and C-N bond cleavage. This can be attributed to the stronger adsorption of quinoline and its intermediates such as 1,2,3,4-tetrahydro-quinoline and 5,6,7,8-tetrahydro-quinoline than that of indole.
Abstract: Amorphous La-Ni-Mo-B catalyst was prepared by chemical reduction method using NaBH4 as a reducing agent and characterized by BET, SEM, XRD and XPS. The hydrodeoxygenation of 4-methylphenol was used as a probe reaction to test its catalytic performance. The results showed that the additive La can decrease the particle size of the catalyst, increase the surface area, and promote the reduction of Ni2+ and Mo6+. The hydrodeoxygenation of 4-methylphenol follows the hydrogenation-dehydration route. The conversion of 4-methylphenol and the selectivity to methylcyclohexane at 275℃ achieve 97% and 96%, respectively. The aromatic content in products is much lower than that of fuel regulation III in the world (aromatics content <15%). The deactivation of the catalyst may be mainly attributed to the destruction of its amorphous structure during reaction.
Abstract: The catalytic oxidation and adsorption capabilities for elemental mercury (Hg0) on activated carbon (AC) were evaluated in a simulated coal-derived gas containing hydrogen sulfide (H2S) and oxygen (O2). The Hg0 removal efficiency is close to 78% in the atmosphere containing H2S and O2 in 180min at 160℃, whereas the retention of mercury without H2S and O2 sharply decreases from 69% to 28% in the same duration. Higher adsorption temperature, larger size of sorbent and higher Hg0 concentration may deteriorate to the absorption capability. XRD was used to characterize properties of the sorbents. It shows that mercury sulfide (HgS) is formed over the AC after the adsorption. It is suggested that the oxidation reaction of Hg0 with H2S and O2 may contribute to the efficient capture of Hg0 over AC sorbent. HgS formation is beneficial to improve the Hg0 removal efficiency and the adsorption capacity of the AC sorbent. Furthermore, it has the advantage to reduce the secondary pollution due to HgS being inert and nontoxic to the environment.
Abstract: The kinetics and thermodynamics characteristics of Pb2+, Cu2+, Zn2+, Cd2+ adsorption onto fly ash from an oil shale-fired power plant was investigated using batch adsorption method. The results show that Freundlich equation is more applicable than Langmuir equation. The adsorption process was studied through fitting of the experimental data using the equation of Lagergren pseudo-first-order kinetics, the pseudo-second-order kinetics, the Elovich equation, and the intraparticle diffusion model. All the four equations were found applicable in initial stage of the adsorption. The absorption of Pb2+, Cu2+, Zn2+, Cd2+ on fly ash from oil shale-fired CFB was in accordance of the pseudo-2nd-order reaction kinetics in the entire stage. The absorption characteristics of metal ions on oil shale fly ash is controlled by both film diffusion and particle diffusion. Thermodynamic analysis show that the processes of oil shale fly ash adsorbing Pb2+, Cu2+, Zn2+, Cd2+ are endothermic reaction.
Abstract: The semi-coke adsorbents were prepared by loading metal oxide on a cheap semi-coke material modified through nitric acid oxidation and high temperature heat treatment. The desulfurization and denitrification and regeneration abilities were investigated. BET, TEM and SEM were employed to explore the effecting factors on the performance of the adsorbents. The results show that the adsorbents have a good denitrification activity and a regeneration ability with water washing when using NO-O2-N2 simulated flue gas. And the adsorbents exhibit an excellent desulfurization activity, especially with the coexistence of NO. However, its denitrification activity decreases rapidly and can not be regenerated effectively for the tests with SO2-O2-N2 and SO2-NO-O2-N2 simulated flue gas. The characterization results indicate that both SO2 and NO can be adsorbed on the adsorbents, and the main reasons for the adsorbents deactivation are its porous channel plugging and surface property variation.
Abstract: In order to provide basic data for the pyrolytic technology of food residue, the study on the food residue pyrolysis in a fixed bed reactor, and the influence of the final pyrolysis temperature, different kinds of food residue and catalysts on the product distribution as weel as the bio-oil composition and characterization was focused. The results show that the optimal temperature of rice and pork pyrolysis for bio-oil producing is 410℃, while that of cabbages is 450℃. The bio-oil yield of rice, cabbages and pork are 45.02%, 25.60% and 71.26%, respectively. The analyses by GR3500-SR1 digital oxygen bomb calorimeter indicate that the high heating value (HHV) of bio-oil of rice and cabbages are 18.30MJ/kg and 17.49MJ/kg, respectively, whereas the HHV of pork pyrolytic oil is 36.57MJ/kg. Compared with the MCM-41 catalyst doped with other metals, Co-MCM-41 catalyst has a particularly evident effect on the food residue pyrolysis. The bio-oil yield is improved from 41.99% to 66.30%. GC-MS was used for studying the components of the pyrolytic oil. The percent of the oxygenated compounds of bio-oil reduces obviously, but the percent of alkane and olefin increases, which results in the HHV of bio-oil to increase from 30.30MJ/kg to 32.74MJ/kg. The regenerated Co-MCM-41 catalyst is characterized by Micromeritics TriStar 3000 physical adsorption analyzer, showing that the pore volume, pore size and specific surface area have little change and the catalyst is still kept activated.
Abstract: In terms of the features of high aromatics, resins and asphaltenes, but low saturates in the heavy fraction (>350℃) of tyre pyrolysis oil, the investigation to use the heavy fraction to produce road bitumen by vacuum distillation was carried out. The results show that the properties of >420℃, >430℃, >440℃ tyre pyrolysis residual oil can meet the technical specification of petroleum asphalts for road pavement, but can not meet the requirements of ageing resistance. The analytic results indicate that the composition of the residual oil changes during the aging process. The content of aromatics and resins decreases and the content of asphaltenes increases variously, which cause the stability of asphalt colloid disperse system to become worse, and the properties of the residual oil after ageing to be deteriorated. But the residual oil shows an excellent ductility because of the extremely high content of aromatics.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
