Abstract: The molecular dynamics simulation, thermal dynamic calculation and experimental investigation were combined to illustrate ash slag viscosity variation mechanism for Al2O3-SiO2-CaO-FeO system. The viscosity declines and the viscosity curve is transformed from crystalline slag to glassy slag with increasing mass ratio (C/F) of calcium to ferrous oxide in Al2O3-SiO2-CaO-FeO system. There is an inflexion point when the C/F is equal to 2. When the C/F is below 2, there are mainly crystalline minerals in the system. While the C/F is above 2, there are mainly amorphous minerals in the system. With the increase of C/F, six-coordinated Al ([AlO6]9-) is transformed to four coordinated Al([AlO4]5-) microscopically. Besides, the content of bridging oxygen decreases while that of non-bridging oxygen increases. Quantified function between base composition and viscosity are constructed based on the stability coefficients defined by oxygen bond species.
Abstract: The acid treatment experiment to remove the inorganic minerals in Xinjiang Hefeng low-rank coal was conducted, and the effects of deashing treatment on the main structure of coal sample and its extraction performance by petroleum ether and CS2 were analyzed by instrumental characterizations. The FT-IR results show that the main structure of the treated coal changes slightly compared with the untreated one. And the acid-washed coal sample (AC) presents a very weak absorption peak at 1712 cm-1 attributed to carboxylic acid (C=O), which could not be observed in the raw coal sample (RC). It can also be seen from TG-DTG characterization that the process of acid treatment results in a cleavage of small molecular bonds in the coal without destroying the macromolecular network structure. The performance of two-stage ultrasonic extraction of RC and AC samples with petroleum ether (PE) and CS2 as solvents proposes that the extraction proportions of PE and CS2 of AC sample are higher than that of RC sample, from 0.16% and 0.53% (RC) to 0.17% and 0.64%, respectively, and the extraction rate of AC sample is larger than that of RC sample, reducing the number of solvent extraction operation significantly.FT-IR and GC-MS analysis of the extracts shows that the acid treatment not only effectively removes the heteroatoms in the coal sample, but also increases the type of CS2 extracts. In addition, from the results of TG-DTG for the residues, it can be noted that the ultrasonic extraction is a physical swelling process, and does not destroy the macromolecular structure of the coal sample.
Abstract: The effects of atmosphere, temperature and catalysts on the BRXL lignite liquefaction conversion and the yield of oil, gas, and water were studied with syngas and complex solvents (water+organic solvent), and the characteristics of BRXL lignite liquefaction were also discussed. The results show that the atmosphere of syngas and the temperature of 430-450℃ are beneficial to coal liquefaction reaction under complex solvents system with catalyst. The coal conversion is 81.15%, and the yield of oil, gas, and water reaches to 71.53%. Besides, the composite catalyst (including iron, base, and sulfur) can effectively improve the coal conversion and the yield of oil, gas, and water. The coal conversion and the yield of oil, gas, and water at 430℃ reach to 92.27% and 79.39%, respectively. Also, the composite catalyst can effectively promote the cracking of macromolecules in coal and the enhancement of water-gas shift reaction, resulting in a decrease of asphaltene and an increase of oil yield. Moreover, the polycyclic aromatic hydrocarbons and derivatives in liquefaction oil can be converted to monocyclic aromatic hydrocarbons and derivatives and alkenes olefins during catalytic liquefaction, resulting in a decrease of compound molecular weight and an improvement of oil quality.
Abstract: For the friendly environmental application of coal tar pitch, the benzoic acid, polyethylene glycol, solid coumarone resin (S) or liquid coumarone resin (L) were selected as a modifier to lower the content of harmful benzopyrene in coal tar pitch by chemical reaction in a tube furnace. The benzopyrene content was detected by an ultraviolet-visible spectrophotometer, and the influence of reaction temperature, reaction time, modifier contents and catalyst types on the benzopyrene content was investigated. The results show that the technical condition has an intimate relationship with the decrease of benzopyrene content owing to the electrophilic substitutive reaction at the existence of acidic catalyst. All modifiers tested have obvious effects on the decrease of benzopyrene content. Under the optimum conditions, the removal rates of benzopyrene by different additives decrease in proper sequence of liquid coumarone resin, polyethylene glycol, benzoic acid and solid coumarone resin. The highest benzopyrene removal rate of 73.0% is obtained by using liquid coumarone resin, showing a promising application prospect.
Abstract: Herein, the synthesis and performance of a novel and stable catalyst capable of facile hydrolysis of bamboo pulp were reported. Based on adopting complex agent to have a complex reaction with Ni2+ cations, the graphitic g-C3N4 phase and nitride phases were formed eventually. The interaction among metals and C, N atoms was analyzed by XRD and XPS. Some Ni-W alloys (mainly NiWO4 was included) were formed besides metallic Ni0 and tungsten species characterized. Particles on the surface of 15%Ni-20%W/MBC@M-0.25 catalyst exhibited homogeneous distribution and surrounded by disordered C3N4 layer characterized by TEM. Besides, the organic N sources were decomposed and the C3N4 phase with high hydrothermal property was formed simultaneously. For catalytic efficiency, 15%Ni-20%W/MBC@M-0.25 catalyst acquired the highest EG yield of 55.8% compared to 36.9% via 15%Ni-20%W/MBC catalysts. The carbon supports and organic nitrogen sources demonstrated great influence on catalytic efficiency. Catalyst recycle experiments implied that Ni-W/MBC@M-0.25 could remain relative stable under this catalytic reaction condition. The Ni-W alloys and the C3N4 phase were deduced as the main contributors to maintain the catalyst stability.
Abstract: The reaction path and the reaction mechanism of water gas shift reaction (WGSR) on the Cu-Pt-Au catalyst surface were investigated using density functional theory (DFT). The stability and electron activity of binary and ternary catalysts composed of Cu, Pt and Au were studied. The synergistic effect of Pt-Au catalyst in binary alloy is better, and the binding energy of Pt3-Au(111) surface is 77.15 eV, and energy level of d-band center is -3.18 eV. When the Pt3-Au(111) surface continues to be doped with Cu, the binding energy of Cu3-Pt3-Au(111) is 77. 99 eV and the center of d-band is -3. 05 eV according to the binding energy and density of stares. The energy barrier of CO oxidization is 4.84 eV in the redox mechanism. The reaction is not easy to follow the redox mechanism. Moreover, the two intermediates CHO and COOH are competitive, the energy barrier of forming COOH is larger than that of forming CHO, the reaction is more easily carried out according to the formic acid mechanism.
Abstract: A new Co/La2O3-La4Ga2O9 catalyst was prepared by reducing LaCo1-xGaxO3 perovskite and used in the direct synthesis of ethanol from CO2 hydrogenation. The composite catalyst was characterized by XRD, XPS, TPD and TEM and its catalytic performance in CO2 hydrogenation was investigated in a micro fixed-bed reactor operated at 230-290℃, 3 MPa, gas hourly space velocity (GHSV) of 3000 mL/(gcat·h) and H2/CO2 molar ratio of 3.0. The results indicate that the Co/La-Ga-O composite oxide catalyst exhibits high selectivity to ethanol in CO2 hydrogenation. In comparison with the LaCoO3 catalyst, the incorporation of Ga dopant can inhibit the formation of CH4 and then promote the production of alcohols, especially ethanol. With a Co/Ga atomic ratio of 7:3, the Co/La-Ga-O composite oxide catalyst displays the best performance in CO2 hydrogenation, with a CO2 conversion of 9.8%, a selectivity of 74.7% to total alcohols and ethanol content of 88.1% (mass ratio) in the alcohols mixture. On the basis of the experimental results, it is speculated that the synergistic effect of surface Co0 and Coδ+ may contribute to the excellent performance of the Co/La2O3-La4Ga2O9 catalyst in CO2 hydrogenation to ethanol.
Abstract: In this work, nitrogen-doped mesoporous carbon (NDMC) was prepared by a hard template method, and the NDMC supported FeCu bimetallic catalysts were prepared by an impregnation method. The physical and chemical properties and CO hydrogenation performance of the catalysts with varying Fe/Cu ratios were studied. The results indicated that Cu-N had strong interaction which directly promoted Cu dispersion on the support. At a relatively high metal loading (45.0%-50.0%), Cu maintained uniform distribution similar to that of N, and the ratios of Fe/Cu on the catalyst surface were smaller than those in the bulk phase, which were different from precipitated Fe-Cu bimetallic catalysts. The XPS results showed that Cu was an electron donor, and the electrons in the Cu-N shifted to Fe. Compared with Fe/NDMC, the reduction of FexCuy/NDMC was facilitated, and their CO hydrogenation activity was significantly increased. Under the pretreatment conditions (H2, 300℃), Fe was not completely reduced, and H might mainly interact with Fe-O in the form of Fe-O-H, while Cu-N interaction was stronger than Cu-H, resulting in a decrease in the ratio of surface active carbon/hydrogen, leading to a gradual increase in C5+ selectivity with the decrease of Fe/Cu ratio. Meanwhile, the introduction of Cu inhibited CO dissociation to some extent, and the electron migration ability of the support to the metal gradually increased with decreasing Fe/Cu ratio, and as a result the surface alkalinity of the catalysts increased with increasing Cu content, leading to further enhancement of C5+ selectivity and alcohol selectivity.
Abstract: A series of Ni2P/Ce-Al2O3 catalysts were prepared by temperature-programmed reduction method, and the influence of Ni2P loading on the catalyst structure and naphthalene hydrogenation saturation performance was investigated. The results show that the specific surface area, the Ni2P particle size and the active site number of the as-synthesized catalysts are greatly affected by Ni2P loading, which is derived from the variable interaction between active component Ni2P and the support Ce-Al2O3. When the Ni2P loading is 17% (mass ratio), the catalyst possesses a large specific surface area (40 m2/g), a small Ni2P particle size (26.3 nm), and the maximum number of active sites (26.7 μmol/g). Meanwhile, the conversion rate of naphthalene and the selectivity of decalin reach to 95% and 76%, respectively, and the activity stability of the catalyst is good, which is mainly attributed to the large specific surface area and high number of active sites of the catalyst providing more sites for the reaction.
Abstract: The deposition-precipitation method was employed for the purpose of bringing in metallic promoters into Ni/Al2O3 catalysts. The effects of various metallic promoters on the catalytic performance in 1, 4-butynediol (BYD) hydrogenation were investigated. Besides, the contents of the suitable promoter were further studied, which were combined with BET, XRD, H2-TPR, EDX-MAPPING, TEM, XPS, and NH3-TPD techniques, aimed at exploring physico-chemical characteristics in catalysts. As the findings suggested, the addition of different promoters substantially impacted the interaction between Ni2+ and support, acting as the key factor impacting the catalytic performance. The introduction of Cu and Fe had the potential to prominently lower the strong interaction between Ni2+ and support for the improvement of the BYD conversion of 95%. Furthermore, different contents of Cu were further studied and discovered that it was the phenomenon of hydrogen spillover arisen on Cu surfaces, efficiently lowering the interaction between Ni2+ and support. Nevertheless, the aggregation in Ni particles cannot be evitable, but for the existence of Ni-Cu alloying in Cu-added catalysts. As the Cu content reached up to 5%, the catalyst manifested the excellent catalytic performance in hydrogenation owing to the abundant amount of Ni0 active sites in the form of the high dispersion and the fitting acidity.
Abstract: Hierarchical SAPO-34 zeolites were successfully synthesized using cheap xylose, sucrose, starch and glucomannan as hard template and characterized by means of XRD, BET, SEM, TEM, ICP and NH3-TPD. The effects of sugar hard template on the structure and MTO properties of as-prepared SAPO-34 zeolites were studied on a fixed bed. The results showed that introduction of carbohydrate hard template could increase the specific surface area, microporous and mesoporous volume of SAPO-34 zeolites. The olefin selectivity and lifetime of SAPO-34 were both higher than those of ordinary SAPO-34. The SAPO-34-z with the largest mesoporous volume, the least acidity amounts and the weakest acidity showed the longest lifetime (130 min), which was 30% longer than that of ordinary SAPO-34 (100 min). The lifetime of zeolites decreased in the order of SAPO-34-z > SAPO-34-h > SAPO-34-d > SAPO-34-m > SAPO-34 > SAPO-34-p. The olefin selectivity of hierarchical SAPO-34 zeolites is higher than that of conventional SAPO-34 zeolites.
Abstract: Amorphous macroporous alumina with three-dimensionally interconnected pore structure was prepared by phase separation technique. The macroporous morphology was modified significantly by hydrothermal treatment with ammonia. There are many plate-like aggregates of alumina with a size of 50-300 nm at the edge of wall; the product is still characterized by the worm-like three-dimensional penetration and uniform spatial distribution, whereas the size of macropores decreases from 430 to 250 nm. The modified alumina material was converted into high crystallinity gamma alumina by calcination at 550℃, which displays a specific surface area of up to 331 m2/g and pore size distributions con-centrated at 8.9 and 250 nm; meanwhile, the Lewis acidity and crushing strength are also improved. It was speculated that the amorphous hydrated hydroxyaluminium ion polymer rehydrated to form boehmite intermediate and transformed into gamma state at low calcination temperature; the AlOOH particles at the edge of macropore wall were then rearranged from inside to outside with NH4+ as template, fabricated into plate-like aggregates.
Abstract: Fe-Mn/Beta catalysts were prepared by incipient wet-impregnation methods and used for selective catalytic reduction of nitric oxide with propylene in excess oxygen. The catalysts were characterized using N2-physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), H2-temperature programmed reduction (H2-TPR) and in-situ diffuse reflectance infrared Fouier transform spectroscopy (in-situ DRIFTS) techniques. The effects of Mn component on the physicochemical properties, C3H6-SCR activity and reaction intermediates of catalysts were also investigated. The results showed that C3H6-SCR activity of Fe-Mn/Beta catalysts at low temperature could be significantly improved by introducing Mn species. 1.5Fe1.0Mn/Beta catalyst achieved the highest activity with a nitrogen oxide conversion of 99.4% at 350℃, which possessed high catalytic performance and N2 selectivity within the temperature window of 250-400℃. Based on the in-situ DRIFT studies, the isolated Fe3+ ions at the ion-exchange sites were the main active sites for selective oxidation of propylene. Although the well-dispersed MnO2 species could not improve the activation ability of the catalysts for propylene, they would enhance the formation of NO2 adsorption species, then promoted C3H6-SCR activity at the low temperature. The significant decrease of SCR activity after hydrothermal aging of Fe-Mn/Beta catalysts might be due to the migration of isolated Fe3+ ions into oligomeric clusters.
Abstract: Nano Y zeolites were synthesized by adding carbon spheres into the synthesis sol of Y zeolites subjected to aging and hydrothermal crystallization; nickel-salt precursors were then loaded by using an incipient-wetness impregnation (IWI) method. After calcination, the nano-NiO-Y composite were then characterized by means of XRD, SEM, TEM, XPS, TG-DTG, and N2 adsorption-desorption techniques and its performance as the cathode material for hydrogen evolution in microbial electrolysis cell was then investigated. The results show that the nano-NiO-Y composite has a crystal size of 500 nm of size and multiple porous structure including micro and mesopores; the total surface area and pore volume of nano-NiO-Y composites are 774.3 m2/g and 0.495 cm3/g, respectively. The electrochemical tests of linear scanning voltammetry and Tafel plots show that as microbial electrolytic cell (MEC) cathode, the nano-NiO-Y composite with a nickel-salt loading of 30% exhibits high electrocatalytic activity. In a continuous operation cycle, the largest hydrogen evolution current density of the nano-NiO-Y composites reaches 22.87 A/m2, and the H2 content is about 73.71% in total gas. The hydrogen production efficiency is 0.393 m3/(m3·d), comparable to that of Pt/C cathode.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
