Abstract: Based on the bench-scale opposed multi-burner (OMB) coal-water slurry gasification experimental platform, the transformation and release characteristics of sodium during the reaction of coal in the gasifier were studied. Particles sampled at different axial distances from burner plane to top and bottom along the gasifier chamber were analyzed. After the microwave digestion and chemical fractionation analysis, the content of sodium was tested by flame atomic absorption spectrometer (FASS). The morphololgy and elements of particles were analyzed by scanning electron microscopy and energy spectrum application system (SEM-EDS). The FASS results showed that the release rate of sodium increased first then decreased with increasing distance to the burner plane. The area near the burner plane was the major release area of sodium. With the reaction in progress in the gasifier the occurrence form of sodium was transformed from water-soluble sodium and ion-exchangeable sodium into the acid-soluble sodium and residual sodium. Combining the SEM-EDS and FASS results, the spherical particles which were formed through melt minerals reacted with sodium in the gas phase to form silicate and sialic acid salt in gasifier. The increasing number of spherical particles led to an increase in the sodium content in the particles.
Abstract: Baiyinhua lignite was sequentially extracted with petroleum ether, cyclohexane, carbon disulfide, acetone, methanol and isometric acetone/carbon disulfide mixed solvent affording extracts, i.e. E1-E6, then extraction residue was sequentially thermal dissolved using methanol, toluene and isomeric methanol/toluene mixed solvent affording soluble portions (SPs), i.e.SP1-SP3. The composition and structural characteristics of extracts and SPs were characterized with Fourier transform infrared (FT-IR) spectroscopy, gas chromatography/mass spectrometer (GC/MS), direct analyze in real time mass spectrometer (DART-MS). The total extracts yield and SPs yield of BL are 9.37% and 21.84%, respectively. There exist strong adsorption peaks ascribed to hydroxyl in the FT-IR spectra of E1 and E6, while the intensity of adsorption peaks ascribed to aliphatic C-H in the FT-IR spectrum of E1 is obviously higher than that of other extracts. There are similar FT-IR spectra among those 3 SPs, whereas the intensity of adsorption peak originated from hydroxyl in the FT-IR spectra of SP1 and SP3 is higher than those of SP2. The compounds GC/MS detected in E1 and E5 are dominated with alkanes and arenes, respectively, and the content of oxygen-containing compounds (OCCs) in E5 are more than that in E1. The compounds in the 3 SPs are composed of alkanes and arenes, while the contents of OCCs, such as phenols, ketones and esters, in SP3 are higher than those in SP1 and SP2. Many compounds with high polarity and low volatility which could not identified by GC/MS were detected using DART-MS. The carbon number and double bond equivalent (DBE) of the compounds with high content in SPs mainly distribute in 10-25 and 2-16, respectively, and the DBE increases with carbon number increasing.
Abstract: Shengli brown coal in 150-180 μm was gasified at 800-900℃ in a simulated entrained-flow reactor, φ80×3 000 mm. Conversion and kinetics of steam gasification reaction of the lignite were discussed to investigate synergistic effects of oxidation reaction on steam gasification reaction. The results show that lignite conversion under H2O+1%O2 atmospheres is greater significantly than the sum of that under H2O atmosphere and 1%O2 atmosphere, i.e., the increase of lignite conversion from H2O atmosphere to H2O+1%O2 atmospheres is greater than that from N2 atmosphere to N2+1%O2 atmospheres. The synergistic effects are caused by promoting effect of oxidation reaction on steam gasification reaction, and are more obvious as H2O content increasing and temperature rising. Moreover, the similar experiments were carried out in φ40×200 mm cylindrical quartz fluidized bed, and the synergistic effects are also found. The steam gasification reaction rate equation, $ (Z-{{(1-x)}^{\frac{1}{3}}})=\frac{t\beta {{k}_{{{\text{H}}_{2}}\text{O}}}}{R{{\rho }_{\text{C}}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}}={{K}_{{{\text{H}}_{2}}\text{O}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}} $, is in good agreement with experimental data. This indicates that the apparent rate constant KH2O increases obviously after O2 adding to water vapor, which is the kinetic characteristics of promoting effect of oxidation reaction on steam gasification reaction.
Abstract: Biomass ashes were prepared from three rich in alkaline and alkaline earth metal materials, viz., wheat straw (WS), sea grape (SG) and ixeris chinensis (IC), at different temperatures of 500, 600 and 815℃; the catalytic effect of biomass ash on the hydro-gasification of Shenfu coal (SF) char was then investigated. The results show that the ash yield and the content of alkali metals and chlorine reduce with increasing ashing temperature from 500 to 815℃; significant ash melting can be observed at high temperature near 815℃. The biomass ashes obtained at 600℃ exhibits the best catalytic effect on the gasification of coal char; the more the ash is loaded with the char, the stronger exhibit the promoting effect on the gasification is. The ash from IC performs best in catalyzing the coal char gasification, whereas the SG ash is the worst catalyst. The high content of silica in the WS ash and the high content of chlorine in the SG ash may explain their poor catalytic effect on the char gasification; chlorine can aggravate the volatilization of alkali metal and lead to a severer inhibiting effect on the coal char hydrogasification than silica with the same molar quantity.
Abstract: The distillation residues from bio-oil and the pyrolysis char obtained at different temperatures were investigated with FT-IR, Raman spectra and TGA. The results show that the distillation residues from bio-oil consist of aliphatic, aromatic and oligosaccharides. The process of thermal weight loss of distillation residues from bio-oil in nitrogen can be separated into three stages. The first is the volatilization of low-boiling point compounds from ambient temperature to 145℃. The second is the pyrolysis, oxidation and polymerization of the heavy compounds at higher temperature and the last is the formation and combustion of coke. The graphitic carbon fraction increases with increasing the carbonization temperature while the disordered carbon amount decreases.
Abstract: The adsorption behavior, decarbonylation and hydrogenation reaction mechanisms of furfural on best Pd/Cu (111) bimetallic model were investigated by density functional theory method. The results show that the initial adsorption at O3-Pd-top and O7-Cu-hcp site is most stable, with the adsorption energy of 73.4 kJ/mol. On the Pd/Cu (111) bimetallic surface, decarbonylation reaction of furfural is more likely to occur. The decarbonylation reaction of furfural has low activation energy. Each steps of decarbonylation mechanism is exothermic reaction. Furfural tends to form (C4H3O) CO by losing the H atom from the branch chain, and furan is then formed by decarbonylation and hydrogenation of the intermediate. Throughout the process, the hydrogenation of C4H3O is the rate-determining step with the highest activation energy barrier of 72.6 kJ/mol. For the hydrogenation of furfural, reacting with the first hydrogen is the rate-determining step, and it has the highest reaction energy barrier of 290.4 kJ/mol.
Abstract: The CuMgAl hydrotalcite-type precursors were prepared by fractional precipitation process with the mass ratio of m(CuO):m(MgO):m(Al2O3)=25:26:49. CuMgAl-t catalysts were calcined at various temperatures. CuMgAl-t catalysts were characterized by BET, TGA, XRD and H2-TPR and CO2-TPD. The catalytic performance of CuMgAl-t catalysts for the gas phase hydrogenation of furfural to furfuryl alcohol was investigated in a fixed bed reactor. The results showed that the calcination temperatures had effect on catalysts activity, stability and product selectivity. The lower temperature calcined catalysts with reduction can obtain more active center and the higher temperature calcined catalysts had more alkaline sites on the surface of catalysts. CuMgAl catalyst calcined at 450℃ had suitable surface active centers and alkaline sites. Under the reaction conditions of atmospheric pressure, reaction temperature of 180℃, molar ratio of hydrogen to furfural of 5 and volume space velocity of 0.3 h-1, the furfural conversion of 98.64% and furfuryl alcohol selectivity of 97.66% were reached over the CuMgAl-450.
Abstract: A series of Ni-W/β zeolite catalysts were prepared via incipient impregnation method in order to improve the yield of 1, 2-propylene glycol (1, 2-PG) in the alcohol products of cellulose hydrogenation. Under the reaction conditions of 240℃ and 6.0 MPa H2 for 30 min, the complete conversion of cellulose was obtained and the yields of 1, 2 propylene glycol and ethylene glycol (EG) were 19.3% and 45.3%, respectively. Different from other supports, the selectivity of 1, 2-PG was highly improved when β zeolite was used. The selectivity of 1, 2-PG was further improved after the addition of alkaline, and the yield of 1, 2-PG was up to 32.5% especially for Ba (OH)2. The function of alkaline catalysts in the reaction was also discussed based on a series of reactions using glucose as the substrate, indicating that alkaline was favorable for the isomerization of glucose to fructose and thus promoted the conversion of cellulose into 1, 2-PG. After two cycles of reuse, the yield of 1, 2-PG and EG slightly decreased (3.9% and 4.1%, respectively).
Abstract: With N-tert-butyl-α-phenylnitrone (PBN) as free radicals trapper, the effects of PBN dosage and reaction temperature on the product distribution and bio-oil component distribution of cellulose liquefaction in supercritical ethanol were investigated using an autoclave. The results showed that the yields of bio-oil and volatile compounds were 37.17% and 50.08% without PBN, respectively; meanwhile the highest yield of bio-oil increased to 48.35%, whereas the volatile compound yield decreased to 35.65% with the PBN dosage increased from 0 to 0.4 g. With the increase of reaction temperature from 250℃ to 340℃, the cellulose conversion rate increased sharply from 23.10% to 88.92% while the bio-oil yield increased from 19.18% to 48.35% (320℃) and the volatile compound yield increased from 6.03% to 50.28% quickly. The GC-MS results showed that the dominant compounds in bio-oil were esters, ketones, alkanes, alcohols, acids and benzenes with the highest relative contents of 27.91%, 15.77%, 13.44%, 12.42%, 16.07% and 19.81%, respectively. The present results proved that PBN has obvious effects on the product distribution and bio-oil component distribution of cellulose liquefaction in supercritical ethanol, especially PBN can enhance the transformation between bio-oil and volatile compounds via reacting with benzyl radicals, methyl radicals, ethyl radicals, etc. The transformation among dominant compounds in bio-oil can be regulated by varying PBN dosage and reaction temperature.
Abstract: The Ce3+-Ti4+-SO42-/MWCNTs catalyst was prepared from the modification treatment of multi walled carbon nanotubes by concentrated sulfuric acid, Ce3+ and Ti4+ through the employing of high temperature impregnation method. Physicochemical properties and structural characteristics of the obtained-catalysts were characterized by means of transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, pyridine adsorption FT-IR spectra, X-ray fluorescence spectroscopy, X-ray diffraction and NH3 temperature programmed desorption. The catalytic activity of Ce3+-Ti4+-SO42-/MWCNTs for the synthesis of biodiesel from the esterification of methanol and oleic acid was investigated. The influence of SO42-/MWCNTs, which was resulted from the addition of Ce3+ and Ti4+, on the structure and catalytic activity was cleared based on the above structure characterization and catalytic activity investigation. The results showed that the conversion of oleic acid reached 93.4% after 5 h reaction at 65℃, when the catalyst/reactants was 1% and the molar ratio of methanol/oleic acid was 12:1. The conversion of oleic acid was 80.8% after the Ce3+-Ti4+-SO42-/MWCNTs were cycled for eight times. Therefore, it can be concluded that this catalyst has high catalytic activity and stability. The high catalytic activity and stability can be explained as follows:the C 1s binding energy of carbon nanotube is much lower than other carbon materials, resulting in easy flow and escape of the electrons in the tubular structure. Thus, the strong interactions will occur among the active groups that have been loaded on the carbon nanotube, which impels Ce3+ and Ti4+ to respectively form stable coordination bonds with SO42-, increases the crystallization degree of the Ce3+-Ti4+-SO42-/MWCNTs catalyst and the active acid sites without increasing the surface defects, and the combination of SO42- and MWCNTs was more stable. In addition, the chemical state of surface atom on the Ti-SO42- was changed due to the strong interaction between SO42- and Ce3+, which strengthened the electron withdrawing ability of S6+ and Ti4+ ions and enhanced the acidity strength of Lewis acid with changing of the acid type. Hence, the Ce3+-Ti4+-SO42-/MWCNTs will be composed by Lewis acid sites mainly, which is favorable for avoiding the occurrence of hydration of acid active sites for the SO42-/MWCNTs catalyst because it was composed of Brönsted acid sites mainly.
Abstract: Four-sized monodispersed ZSM-5 crystals, being 70, 200, 400 and 650 nm, were hydrothermally synthesized by changing the H2O/Si molar ratio in the synthesis gel, and characterized with XRD, TEM, BET and NH3-TPD techniques. The crystal size effect of ZSM-5 on its catalytic performance for conversion of methanol to gasoline (MTG) was investigated. It was shown that the external surface area of the sample decreased with its crystal size, while the acid site amount firstly increased, and then kept almost constant. Nevertheless, 650 nm ZSM-5 crystals attaching small particles exhibit large external surface area and strong acidity. The catalytic stability and the liquid hydrocarbon yield decreased with increasing crystal size. The sample with a crystal size of 70 nm shows a catalytic lifetime of 96 h and a gasoline yield of 30.8%. The large external surface area and relatively strong acidity endow the sample with a crystal size of 650 nm also has a catalytic lifetime of 91 h, indicating that synthesis of large ZSM-5 crystals with small crystallites adhered to their surface could be a potential way to improve the catalytic performance.
Abstract: The liquid ion exchange method was employed to prepare cerium (Ce) cation modified Y zeolite (CeY) with various amount of cerium using different types of Y zeolite (HY, USY and NaY) and characterized by X-ray fluorescence spectrometry (XRF), intelligent gravimetric analyzer (IGA) and a molecular simulation technology (Grand Canonical Monte Carlo simulation, GCMC). A novel calculation method of desorption index (DI) has also been proposed to study the influence of cerium cations on the processes of adsorption-desorption of hydrocarbon molecule (benzene) on the CeY zeolites. The saturated adsorption capacity of benzene, adsorption interaction, desorption thermodynamic parameters, potential distribution curves and diffusion processes of benzene in CeY zeolites were analyzed. The results indicate that Ce ion can reduce the desorption activation energy, weaken the adsorption interaction force between benzene and Y zeolites, and modulate the adsorbed state of benzene molecules from agglomerate state to dispersed state, which are main factors to optimize the product selectivity of light oil components in the fluid catalytic cracking (FCC) process with CeY zeolite catalyst.
Abstract: Micro-mesoporous Hβ/Al-SBA-15 composite molecular sieves was prepared by post-synthesis method and characterized by XRD, N2 sorption, Py-FTIR, NH3-TPD, SEM and TEM. With the Hβ/Al-SBA-15 composite as support, Ni-W/Hβ/Al-SBA-15 catalyst was prepared through impregnation and its catalytic performance in the hydrocracking of naphthalene to BTX was investigated. The results verified that the Hβ/Al-SBA-15 composite are provided with both micropores and mesopores. Both Bronsted acid and Lewis acid sites are present on the surface of Hβ/Al-SBA-15 and its acidity is stronger than that of SBA-15. After loading Ni and W, the Ni-W/Hβ/Al-SBA-15 catalyst with moderate acidity and micro-mesoporous structure exhibits high activity in the hydrocracking of naphthalene to BTX; the conversion of naphthalene reaches 96%, with the selectivity of 61.1% to BTX.
Abstract: Activated carbons (AC) were obtained through carbonization of polyaniline and modified lignosulfonate composite (PAn-MLS) under different temperatures; they are characterized by fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, nitrogen sorption and scanning electron microscope (SEM). With these carbon materials as the support, a series of Pd-AC catalysts for the oxidation of formic acid were prepared by liquid phase reduction and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and electrochemical analysis. The results show that with the activated carbon prepared at 800℃ (AC800) as the support, the Pd-AC800 catalyst obtained performs best in the oxidation of formic acid; the palladium particles have an average size of 5.4 nm and the electro-active surface area reaches 53.78 m2/g. As the oxidation of formic acid over Pd-AC800 is realized through direct pathway rather than CO pathway, Pd-AC800 may be considered as a potential electrode material in direct formic acid fuel cells (DFAFC).
Abstract: ZSM-5 zeolites were modified with different contents of monovalent copper by solid-state ion exchange method and used as the catalysts in soot oxidation; the effect of monovalent copper content on the catalytic performance was investigated through extensive characterization. The results indicate that high content of monovalent copper can be loaded on ZSM-5 zeolite by the solid-state ion exchange method, whereas has little detriment to the original micro-structure of ZSM-5. With the increase of copper content in catalyst, the reduction peaks at low temperature and high temperature both shift to lower temperature, while the area of low temperature reduction peak is increased. The catalytic activity of Cu-modified zeolite in soot oxidation decreases after an initial increase with the increase of Cu content. When the Cu loading exceeds 11%, the dispersion of copper species deteriorates, accompanying with a decrease in the catalytic activity for soot oxidation. Meanwhile, the addition of NO to the feed (O2/He) can enhance the soot oxidation.
Abstract: Considering the technical requirements for middle-low temperature denitration of flue gas, a series of powder and plate type V2O5-MoO3/TiO2 SCR catalysts were prepared using incipient wetness impregnation method with V2O5 as the active component and with MoO3 as the promoter. Experiments were performed to investigate the effects of active component and promoter contents of the catalysts on the activities and the resistance to deactivation by SO2 and H2O. The characterization of the fresh and used catalysts was conducted, and the optimal catalyst was further studied to reveal the denitration performance under different flue gas conditions. The results indicate that the activities of the catalysts are enhanced with the increase of V2O5 loadings. Also, the addition of MoO3 can promote the catalytic activity. The characterization results from XRF, XPS, FT-IR and other analysis suggest that the MoO3 content could affect the V4+/V5+ ratio in the catalyst. The increase in relative MoO3 content is favorable for the formation of non-stoichiometry vanadium species as well as the rise of chemical adsorption oxygen. Therefore, the interactions between molybdenum and vanadium species might be an essential reason for the resistance to the deactivation by SO2 and H2O. The denitrification efficiency of 3V2O5-10MoO3/TiO2 plate catalyst keeps steady around 82% after 30 days test in the presence of SO2 and H2O at temperature of 200℃ and space velocity of 3 500 h-1. The catalyst is identified to have an excellent resistance to the deactivation by SO2 and H2O under middle-low temperatures.
Abstract: The reaction mechanism of CaO with HCN during low temperature sludge pyrolysis was investigated by density function theory. The geometric optimization and frequency calculations of reactants, products, intermediates and transition state in the reaction pathway were performed at B3LYP/6-311++(3df, 2p) level; single point energy calculation was performed at CCSD (T)/cc-pVQZ level and the total energy was corrected by zero-point energy at B3LYP/6-311++(3df, 2p) level. The results indicate that largest energy barrier (310.33 kJ/mol) appears in proton transition process after 2 HCN molecules are adsorbed on CaO. Arrhenius equation for each step was fitted by classical transition state theory and the reaction rate was calculated at 3 typical temperatures. The results suggest that proton transition is the rate-determining step; moreover, the promoting effect of CaO on HCN is enhanced with the increase of temperature.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
