Abstract: The bromine content of 305 coal samples from 27 provinces, municipalities and autonomous regions of China were tested, then the distribution of bromine with different geological ages, coal ranks, coal-cumulating areas was analyzed. The results show that the coals with moderate and low bromine content are predominant in China. The bromine content ranges from 0.12 to 69.66 μg/g, and it follows a logarithm normal distribution. Thus the geometric mean, 7.04 μg/g, is regarded as the average bromine content in Chinese coals. This is less than that in many countries and close to the average bromine content (7.10 μg/g) in Japanese coals. In Chinese coals, the average bromine content is less than 5 μg/g in 13 districts, 5~15 μg/g in 9 areas, and more than 15 μg/g in 5 regions. Based on coal rank, bromine content decreases gradually from bituminous coal, anthracite, lignite to subbituminous coal. As for coal-forming period, bromine content decreases from Early carboniferous through Late Permian, Late Carboniferous, Early Permian, Middle Jurassic, Late Triassic, Early Jurassic, Late Jurassic, Tertiary to Middle Carboniferous. According to coal-cumulating areas, bromine content decreases from northwestern China, northern China, southern China, Yunnan and Tibet to northeastern China. But all of them have no notable effect on the bromine content in Chinese coal.
Abstract: The association behavior of coal tar pitch soluble components TS in toluene was studied by hydromechanics method. The critical association concentrations of TS in toluene were obtained by viscosity curves at different temperatures. The kinetics parameters of nucleation and micelle stage in association process were calculated. The results show that the viscosities of TS solution increase with increasing concentrations at 293~353 K, and the turning-points appear between 13 and 26 g/L. The turning-points shifted backward along the axis with increasing temperatures. Both the nucleation and micelle stage are first-order associated reaction. The activation energies for the two stages are 17.25 and 12.41 kJ/mol, respectively.
Abstract: The asphaltene extracted from coal liquefaction residue was studied by 13C-CP/MAS NMR, elemental analysis, FT-IR and XPS to reveal its aromatic unit structure and relative structural parameters. The results show that the ratio of bridged carbon to the surrounding carbon of asphaltene is 0.115. Benzene is the main form of aromatic carbon, and aliphatic structure exists mainly in the forms of alkanes and cyclic-methylene. Oxygen atoms present as carboxyl and ester group and nitrogen atom exits in the form of pyrrole. Based on structural parameters and analytic characterization, macromolecular structure model of refined asphaltene is constructed. 13C chemical shift of refined asphaltene is calculated by ACD/CNMR predictor. According to the calculation results, macromolecular structure model of refined asphaltene is corrected, and finally the calculated chemical shift diagram of model can tally well with the experimental result.
Abstract: A kinetic model for Shenfu (SF) coal liquefaction catalyzed by Ni-Mo-S/Al2O3 was built by using lumped kinetic method, where the liquefaction products were fractioned by solvents. The model has considered the mutual transformations among coal, preasphaltene (PA), asphaltene (AS) and oil in the process, in which a series of consecutive, parallel, regressive and coking reactions were integrated. The results showed that the process of SF coal liquefaction catalyzed by Ni-Mo-S/Al2O3 can be well simulated by the model; based on this kinetic model, the activation energy of SF coal liquefaction is 125~244 kJ/mol. There exist obviously regressive reactions of oil and gas to AS and AS to PA at high liquefaction temperature. Moreover, the coking reactions of AS and PA to coke may take place when the liquefaction temperature exceeds 420℃.
Abstract: The releasing characteristics of alkali and alkaline earth metals (AAEMs) during CO2 gasification process of biomass and pyrolyzed char were explored in a fixed bed reactor. The amount of AAEMs releasing during the gasification of various feedstocks at different pyrolysis temperatures was determined by atomic absorption spectroscopy. Differences in weight loss of biomass during gasification are resulted from the diversity of volatile content in different biomass feedstocks. Along with the increasing of pyrolysis temperature, the reactivity of char gasification is decreased. It is found that the releasing amount of Na is larger than that of K, and that of alkaline earth metals is less, which is related to their existence form and metal valence. The increasing of pyrolysis temperature can improve the release of K at low temperatures, while it has little influence on the release of Na during the whole pyrolysis and gasification process. The type of biomass especially the Si content in ash has a significant impact on the migration of Ca and Mg, and higher char gasification conversion leads to a larger releasing amount of AAEMs. Results of thermodynamic calculations show that K and Na are released mostly in the form of chloride, while Ca and Mg mainly exist in the form of silicate which is hard to release.
Abstract: The characteristics of thermal cracking, kinetics and product gas during co-pyrolysis of different mixtures of larch sawdust and waste tire (1:2, 1:1 and 2:1) were investigated using a thermogravimetric analyzer coupled with Fourier Transform Infrared (TG-FTIR). The weight loss curves show that the process of co-pyrolysis is dominated by the larch thermal degradation before 366℃ and by the rubber thermal degradation after 366℃. The pyrolysis efficiency is improved as the ratios of larch sawdust increase. The kinetic model of Coats-Redfern was used to analyze the kinetic behaviors. It is found that the pyrolysis behavior accords with the first-order kinetics, and the activation energy in the high temperature range (370~480℃) is much smaller than that in the low temperature range (250~370℃), moreover, the pyrolysis reaction is easier to occur because the activation energy decreases with increasing the ratios of larch sawdust. The results of infrared analysis show that the organics with oxygen-containing functional groups and small molecules are main product produced. During the process of pyrolysis, the amounts of six kinds of small molecular gases produced are in the order of CO2>CH4>H2O>CO>SO2>H2S, and S is mainly converted to SO2 due to the effect of oxygen free radical, which is produced in the thermal degradation of larch wood.
Abstract: Upgrading the oil-soluble fraction, which was obtained by water extraction of bio-oil from fast pyrolysis of rice husk, was investigated with simultaneous esterification and acetalation in butanol with online solvent extraction (SEAWOSE). The results show that almost all of the acids, aldehydes and ketones in the oil-soluble fraction can be converted to the corresponding esters, hemiacetals and acetals by SEAWOSE. In comparing with direct esterification and acetalation without extraction, the char formation is significantly suppressed. Meanwhile, the upgraded oil has very low acidity and moisture content, but high heating value and good volatility. The effect of oxidation and reduction pretreatment of the oil-soluble fraction before SEAWOSE was also investigated. By hydrogen peroxide oxidation, the aldehydes are firstly converted into acids and subsequently esterified to esters, consequently without char formation. The upgraded oil is high quality, less than 4% in moisture, higher than 30 MJ/kg in heating value and less than 2 KOH mg/g in acidity.
Abstract: The density functional theory B3LYP/6-31G(d,p) was used to study the reaction mechanism of β-1 type lignin dimer gasification with high temperature steam based on quantum chemistry. The results show that the enthalpies of R4 and R5 in the beginning of reaction of lignin model compound with high temperature steam, are 243.9 kJ/mol and 323.2 kJ/mol, respectively. These values mean that Cα-Cβ bond and Cβ-C1 bond are easy to break. By the calculation, R4-1 and R5-1 reaction barriers are 4.4 kJ/mol and 24.0 kJ/mol, respectively. Thus it is of priority to choose the R4-1 and R5-1 paths in the gasification process. Products via the reaction path calculation include ethanol, methanol, phenol hydroxy toluene and p-hydroxybenzaldehyde, which agree with the experimental results.
Abstract: Sorbitol and xylitol were used as raw materials for the preparation of heavier hydrocarbons by reduction with hydriodic acid under mild reaction conditions. The generated liquid hydrocarbons were analyzed by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FT-IR). Their physicochemical properties were further characterized. The heavier hydrocarbons obtained from sorbitol mainly include C12H16, C12H18, C12H20, C12H22 and C18H26, with a yield of 85.1%. In contrast, that prepared from xylitol were mainly composed of C10 and C15 hydrocarbons with a yield of 62.8%. When using a mixture of sorbitol/xylitol (50:50) as feedstock, C11 hydrocarbons were also generated besides C10,C12,C15 and C18 hydrocarbons. The yield of total heavier hydrocarbons was 65.4%. To get purer liquid hydrocarbons, the obtained raw product was treated with potassium hydroxide in an ethyl alcohol solution, followed by rotary evaporation and vacuum distillation, and a liquid hydrocarbon fuel contains less than 0.2% of water and 1.8%~2.1% of oxygen was generated. Its kinematic viscosity is 3.15~ 3.17 mm2/s, density 0.83~ 0.84 g/mL, and calorific value greater than 43 MJ/kg at room temperature. The umpolung of the C-I bond and the intermolecular C-C coupling may result in the formation of heavier hydrocarbons from polyols.
Abstract: A series of Fe/SiO2 catalysts were prepared by one-pot synthesis and conventional co-precipitation methods; they were characterized by N2 physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and temperature-programmed reduction. The performances of the Fe/SiO2 catalysts in Fischer-Tropsch synthesis (FTS) were evaluated in a fixed-bed reactor for the production of light olefins from syngas. The results showed that in the Fe/SiO2 catalyst prepared by one-pot synthesis method, the iron oxide is present as iron-silica nanocomposite in the form of Fe3O4 (magnetite). Compared with the catalyst prepared by conventional co-precipitation method, the magnetite-silica nanocomposite by one-pot synthesis exhibits a more uniform spherical-like morphology, narrower size distribution (30 nm in average) and better reducibility. In FTS, the Fe/SiO2 catalyst prepared by one-pot synthesis method exhibits higher activity and selectivity to light olefin as well as lower selectivity to methane and better stability.
Abstract: Poisoning effect of dimethyl disulfide (CH3SSCH3) on Ni/Al2O3 catalysts for hydrogenation of benzene, cyclohexene and styrene was studied. The structures and properties of the catalysts were investigated by means of BET, XRD, H2-TPR, XPS, SEM and EA. Results indicated that with the existence of CH3SSCH3, Ni/Al2O3 catalysts quickly deactivated for benzene and cyclohexene hydrogenation, while the activity for styrene hydrogenation remained well. The sulfur tolerance of Ni/Al2O3 catalysts for cyclohexene hydrogenation was little better than that of benzene hydrogenation. The conversion of conjugated double bond of styrene can keep 100% for a long time. For hydrogenation reactions, the poisoning effects of CH3SSCH3 over Ni/Al2O3 were in the order of aromatic nucleus>monoene>conjugated alkene. In addition, poisoning mechanism of CH3SSCH3 for Ni/Al2O3 catalyst was also discussed. CH3SSCH3 molecules were firstly adsorbed on the surface of catalyst and then dissociated to CH4 under the function of hydrogen and catalyst. It is concluded that the toxicity of carbon in CH3SSCH3 for catalysts is neglectful and remaining sulfur is the dominant poisoning factor by the interaction with active component.
Abstract: Fe-modified Ru/Al2O3 (Ru-Fe/Al2O3) catalysts were prepared by adsorption-precipitation (AP) method with alumina as the support and characterized by H2-TPR, XRD and XPS; the effect of Fe modification on the catalytic performance of Ru-Fe/Al2O3 was investigated in the selective hydrogenation of dimethyl meleate (DMM) to dimethyl succinate (DMS). The results indicated that through the modification with a Fe/Ru atomic ratio above 2, the catalytic performance of Ru-Fe/Al2O3 and its stability towards high temperature oxidation-reduction treatment is obviously enhanced. Under 70℃, 1.0 MPa and with a stirring speed of 600 r/min, the conversion of DMM and the selectivity to DMS were both nearly 100%. The XPS and H2-TPR results suggest that the promoting effect of Fe on Ru-Fe/Al2O3 may be ascribed to an increase of Ru dispersion as well as a change in Ru electronic state through the modification with Fe.
Abstract: Boron-doped silicon carbide (B0.1SiC) synthesized by the carbothermal reduction method was used as support to prepare Pt/B0.1SiC catalyst by cyclic voltammtric deposition of Pt nanoparticles. The crystal structure, surface property and morphology of the catalysts were studied with X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques and N2 adsorption-desorption experiment. It is shown that B atoms have been incorporated into the SiC lattice sites by substituting Si,which increases the electrical conductivity of SiC. Pt nanoparticles uniformly dispersed on the B0.1SiC support with an average size of 2.7 nm. The prepared Pt/B0.1SiC had a larger electrochemically active area and exhibited higher electrocatalytic activity and stability for methanol oxidation than the Pt/SiC synthesized by the same method. This shows that B-doped SiC is a promising support for preparing high-performance methanol oxidation electrocatalysts.
Abstract: PdAuIr/C-Sb2O5·SnO2 electrocatalysts with Pd:Au:Ir molar ratios of 90:5:5, 70:20:10 and 50:45:5 were prepared by borohydride reduction method. These electrocatalysts were characterized by EDX, X-ray diffraction, transmission electron microscopy and the catalytic activity toward formic acid electro-oxidation in acid medium investigated by cyclic voltammetry (CV), chroamperometry (CA) and tests on direct formic acid fuel cell (DFAFC) at 100℃. X-ray diffractograms of PdAuIr/C-Sb2O5·SnO2 electrocatalysts showed the presence of Pd fcc phase, Pd-Au fcc alloys, carbon and ATO phases, while Ir phases were not observed. TEM micrographs and histograms indicated that the nanoparticles were not well dispersed on the support and some agglomerates. The cyclic voltammetry and chroamperometry studies showed that PdAuIr/C-Sb2O5·SnO2 (50:45:5) had superior performance toward formic acid electro-oxidation at 25℃ compared to PdAuIr/C-Sb2O5·SnO2 (70:20:10), PdAuIr/C-Sb2O5·SnO2 (90:5:5) and Pd/C-Sb2O5·SnO2 electrocatalysts. The experiments in a single DFAFC also showed that all PdAuIr/C-Sb2O5·SnO2 electrocatalysts exhibited higher performance for formic acid oxidation in comparison with Pd/C-Sb2O5·SnO2 electrocatalysts, however PdAuIr/C-Sb2O5·SnO2 (90:5:5) had superior performance. These results indicated that the addition of Au and Ir to Pd favor the electro-oxidation of formic acid, which could be attributed to the bifunctional mechanism (the presence of ATO, Au and Ir oxides species) associated to the electronic effect (Pd-Au fcc alloys).
Abstract: Pillared MCM-36 zeolites of MWW type were hydrothermally synthesized by pillaring swollen layered MCM-22P precursor, with tetramethylammonium silicate as the pillaring reagent; the synthesized zeolites were characterized by different physico-chemical techniques such as XRD, N2 adsorption, TEM, 27Al-MAS, NMR and NH3-TPD. The results showed that the swollen MCM-22P without drying was successfully pillared in an aqueous solution system; the MCM-36 zeolites with an uniform interlayer distance were then readily obtained. The suitable synthesis conditions for MCM-36 are 80℃ for 24 h for the interlayer swelling of MCM-22P at high pH value (13.5), and then at 100℃ for 24 h for the formation of the intercalating pillars. The MCM-36 zeolites obtained exhibit a typical MWW topology structure, with a composite pore system of both micropores in the crystalline layers and mesopores in the interlayer space, and a large specific surface area (especially external specific surface area). Compared with HMCM-22, the HMCM-36 zeolites show lower acid amount; however, a larger amount of structurally accessible Brnsted acid sites located in the interlayer space of MCM-36 zeolites are exposed due to the formation of mesopores in the interlayer space, which should be favorable to the reaction involving bulky molecules.
Abstract: The catalysts with SBA-15, MCM-48, SiO2, and MTS-9 as supports were synthesized with 8% WO3, and their catalytic performance for metathesis of butene to propene were carried out. The conversion of butene is 30%~37% on the catalysts with SBA-15, MCM-48, and SiO2 as supports, and that of butene is 37%~42% on WO3/MTS-9 catalyst. The catalyst characterization results show that the catalytic activities depend on the acidic numbers of catalysts prepared and the distribution of tungstens on the supports used. As a result, the performance of 8% WO3/MTS-9 catalyst for the titled reaction is best.
Abstract: Choline chloride/oxalic acid as a eutectic solvent was synthesized by the reaction of choline chloride with oxalic acid at 100℃ via simple stirring. The removal of dibenzothiophene (DBT) in model oil was carried out by using choline chloride/oxalic acid as a catalyst, hydrogen peroxide as oxidant, imidazolium tetrafluoroborate ionic liquid as extractant; the influence of reaction temperature and time, the amount of hydrogen peroxide, the type of extractant, the type of sulfur-containing compound (thiophene and its homologues) on the desulfurization efficiency were investigated. The results indicated that under the optimal reaction conditions of n(H2O2)/n(S)=8, reaction temperature of 30℃ and time of 80 min, the desulfurization efficiency for DBT reaches 95%. Moreover, the reaction system can be recycled for 5 times without a significant decrease in the desulfurization activity.
Abstract: The catalyst of cobalt oxide supported on Hβ zeolite (Co/Hβ) was prepared by impregnation method and characterized by XRD, H2-TPR, NH3-TPD, and SEM. The effects of calcination temperature and cobalt loading on the catalytic performance of Co/Hβ in N2O decomposition were investigated. The results showed that cobalt species are present mainly in the form of Co3O4 spinel oxide. The acidity, acid amount and redox property of the Co/Hβ catalyst were significantly affected by the calcination temperature; the Co-Al-O species that is difficult to reduce by hydrogen is formed at a calcination temperature over 700℃. The catalytic activity of the Co/Hβ catalyst was affected by the calcintion temperature and cobalt loading. The Co/Hβ catalyst calcined at 600℃ and with a cobalt loading of 10%~15% exhibits excellent catalytic activity in N2O decomposition; the temperatures t10, t50 and t95 for N2O decomposition are 325~329℃, 364~367℃, and 406~408℃, respectively.
Abstract: A series of magnesium-based CO2 absorbents with different Na/Mg molar ratios were prepared by precipitation method with Mg(NO3)2 and Na2CO3 as raw materials, and characterized by various methods (including XRD, SEM-EDS and DTG) to study the compositions, morphology and decomposition temperature and so on. The CO2 absorption performance was evaluated by temperature swing absorption-desorption dynamic cyclic tests to check the impact of Na/Mg molar ratio. It can be seen that optimum molecular ratio of Na to Mg is 8.15, and the sorbents is homogeneous with lower decomposition temperature caused by small particles of the sample, and initial CO2 adsorption capacity can reach 9.584%. Good recycling capability can be obtained as well. Compared with the initial absorption capacity, there was only 4.2% decrease after 20 recycles.
Abstract: The microwave regeneration of SO2 loaded activated carbon (AC) and its circulation adsorption characteristics were studied. The effects of microwave regeneration on the pore texture and surface chemistry of AC were analyzed by SEM, low temperature N2 adsorption, elemental analysis and Boehm titration. The results show that microwave irradiation is an effective regeneration method. In the suitable regenerative power, after many circulation adsorption/regeneration, the AC still remains high adsorption capacity. After 17th circulation, the adsorption capacity of AC is still higher than the primitive AC. Hower, there is obviously weight loss for AC during the regeneration because of the reaction between C and H2SO4. After first regeneration, the surface acidic functional groups of the AC almost decompose at high temperature, and the surface basic functional groups increase, so the SO2 adsorption capacity of AC is enhanced. After several adsorption/regeneration circulations, the surface acidic functional groups and basic functional groups remain stable, while the pore structure of AC becomes long and narrow for the activation of regeneration. And the specific surface area and volume of micropore increase, which benefits the SO2 adsorption on AC.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
