Abstract: The product yields and gas composition were examined for fast co-pyrolysis of bituminous coal with either hemicelluloses-rich corncob or lignin-rich pine sawdust. The results indicate that the interactions among pyrolysis products cause an obvious difference in the yields and gas composition during the co-pyrolysis processes. As compared with pyrolysis of individual fuels, the co-pyrolysis of corncob can generate more CO2 and H2O due to its high content of hemicelluloses. K in biomass is easy to evaporate and transfers to the surface of coal char. The catalytic effect of K can promote the gasification reactions of coal char with CO2 and H2O to produce activated H and hydrogen-rich components, which can couple with radicals to inhibit polycondensation reactions between macro radicals. As a result, the co-pyrolysis increases the gas and liquid yields and decreases the char yield. For co-pyrolysis of bituminous coal and pine sawdust, Ca in pine sawdust can transfer to the surface of coal char to promote the cracking reactions of tar liquids and generate more CO2, CO and hydrogen-rich radicals. The co-pyrolysis reduces the char and liquid yields and raises gas yield. The gasification and cracking reactions of pyrolysis products (char, liquids and gases) produce more secondary hydrogen-rich components to raise hydrocarbons and CO content in the gaseous products.
Abstract: Wettability and adsorptive mechanism of coal tar pitch by aqueous solutions of cationic surfactant (C12-m-C12·2Br-, m=4, 6, 8, 10)were investigated by the sessile drop analysis and electrophoresis. The results indicate that the surface tension decreases with increasing surfactant concentration up to the CMC (critical micelle concentration) of the surfactant solution, which θ and S have the similar trend with surface tension. Within the whole range of concentration, the Zisman theory is in accordance with the wettability on the coal tar pitch when spacer chain length value reaches to 10. Meanwhile, there is a liner dependence between adhesion tension (γlgcosθ) and surface tension (γlg). Zeta potential on the surface of the coal tar pitch increases with the increasing surfactant concentration from negative to positive, and finally levels off. And the concentration of the zero potential is lower than CMC at least an order of magnitude. C12-8-C12 Gemini surfactants can significantly change the wettability on the surface of the coal tar pitch. According to the wetting data and Zeta potential of Gemini surfactant on coal tar pitch, it can be inferred that wetting is a concerted action result of electrostatic interaction and van der waals adsorption. Therefore, wetting process can be generally divided into three phases.
Abstract: By using a coke gasification reaction device and an online measurement apparatus of high-temperature compressive strength, the variation of pore structures of coke after gasification with CO2 and steam was investigated. In addition, the influences of solution loss rate, temperature and pore structure on the high-temperature compressive strength of coke were also studied. The results show that compared with that in CO2 gasification, the average pore diameter of coke becomes smaller, and the specific surface and the quantity of pore under 100 μm increase in steam gasification. Meanwhile, the global high-temperature compressive strength becomes higher. After reacting with CO2 and steam, the high-temperature compressive strength of coke will decrease with the increasing of solution loss or temperature. When the coke is gasified at 1 200 ℃, its work(WOCu) during deforming process will decrease gradually with solution loss. The work(WOCu) is higher for steam gasified coke than that for CO2 gasified coke. The deformation shows a trend of decrease with solution loss. At the same solution loss, compared with that after CO2 gasification, the damage of pore structure variation to the coke strength after gasification with steam is relatively smaller and the deformation resistance is stronger.
Abstract: The influence of particle size on oil yield from pyrolysis of Huadian oil shale was investigated. The raw material was crushed and sieved to 6 fractions with different particle size: <0.074, 0.074~0.125, 0.125~0.25, 0.25~0.5, 0.5~1 and 1~3 mm. Then, the fraction of 0.25~0.5, 0.5~1 and 1~3 mm were ground to obtain the corresponding powder samples. A standard method and thermogravimetric analysis were applied to measure and characterize the oil yield and organic matter content in different samples. The results show that both the oil yield (from 11.92% to 6.14%) and organic matter content decrease gradually with decrease in particle size, and a significantly linear relationship is observed between oil yield and organic matter content. The oil yield for powder sample of 0.25~0.5, 0.5~1, and 1~3 mm decreases, while gas yield increases, but the variation is slight and below 1%. Both preferential distribution of organic matter and secondary reaction of shale oil determine the oil yield of fractions with different particle sizes. Furthermore, the selective enrichment of organic matter is the predominant factor.
Abstract: The gelling properties of biodiesels were studied with rheometer in the modes of small amplitude oscillatory shearing. The results show that in addition to the cooling gelling properties, biodiesels also show obvious isothermal gelling properties at low temperatures. The effects of cooling rate and shear stress on the gelling properties of biodiesels were studied. The gel point of biodiesel decreases and the strengths of gel structure at the same temperature during cooling and isothermal gelling process weaken with the increase of cooling rate under quiescent conditions. At the same cooling rate, the gel strength during cooling and isothermal gelling process is much weaker with increasing shearing stress. However, the gel strength of biodiesel has little difference after isothermal gelling process although the shear stress applied during cooling process is different. During cooling the gel strength decreases with the increase of cooling rate when the applied shear stress is smaller; but the gel strength increases with the increase of cooling rate when the applied shear stress is larger. No matter the shear stress' values applied in cooling process, the gel structure is enhanced with the increase of cooling rate during the isothermal gelling process.
Abstract: A series of sulfonato-salen metal complexes were intercalated into Mg-Al layer double hydroxide (LDH) and used for selective oxidation of glycerol to dihydroxyacetone (DHA). The X-ray diffraction, Fourier transform infrared spectroscopy and elemental analysis results of the as-prepared catalysts demonstrated that the metal ions were combined with sulfonato-salen ligands to form metal complexes that intercalated in the LDH. The Cr(III) and Cu(II) sulfonato-salen complex-intercalated LDH catalysts were favorable for activation of H2O2, promoting the oxidation of glycerol to DHA. It was found that the Cu(II) sulfonato-salen-intercalated LDH catalyst was also beneficial for the dehydrogenation of glycerol, resulting in a high selectivity to DHA. The glycerol conversion and DHA selectivity obtained over the Cu(II) sulfonato-salen-intercalated LDH catalyst reached 40.3% and 52.9% respectively under the optimum reaction conditions of 60 ℃, 4 h and pH value 7.
Abstract: Al2O3, CeO2, TiO2 and MgO supported Ni catalysts were prepared by incipient impregnation. The activities in glycerol steam reforming to hydrogen production were evaluated at 300~500 ℃. The catalysts were characterized by XRD, N2 adsorption, TEM, and H2-TPR techniques. A strong effect of support on the activity of Ni catalyst was detected. Ni/CeO2 catalyst gives the highest activity among all catalysts at 400 ℃and the following activity order is shown Ni/CeO2> Ni/Al2O3 > Ni/TiO2 ~ Ni/MgO. On Ni/CeO2, there was almost no deactivation detected after 20 h reaction with 70% conversion of glycerol and 69.2% H2 yield. Good activity and stability of the catalyst is attributed to the intrinsic property of CeO2 and strong interaction between CeO2 and active nickel species. Relatively high glycerol conversion (85.7%) with low H2 selectivity on Ni/Al2O3 catalyst at 500 ℃ is achieved due to its high surface area and large pore volume. The formation of solid solution NiMgO2 phase observed in Ni/MgO catalyst does not show the desired activity at low temperatures though it enhanced the interactions between active phase and the support. Base oxide supports (CeO2, MgO) seem to be more effective than acid oxide supports in preventing the formation of CO and CH4 as by-products.
Abstract: The monodisperse SiO2 microspheres with average diameter of 230 nm made by optimized Stöber method were used as core to prepare core-shell structure SiO2@Fe2O3 catalysts with different shell thickness through hydrolysis precipitation. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 physical adsorption and X-ray diffraction (XRD) were used to characterize the size, structure and morphology of catalysts and the effects of different preparation condition on morphology were discussed. The characterization results indicate that SiO2@Fe2O3 catalysts possess obvious core-shell structure and the spherical morphology of catalyst is kept. Iron oxide nanoparticles are attached to the silica surface through hydroxyl-bond and a 2~10 nm thick dense shell is formed.
Abstract: A series of CeO2-ZrO2-WO3 catalysts (CZW) was prepared by the hydrothermal method. The effect of WO3 content on their catalytic properties for selective reduction of NO<em>x with NH3 was investigated. The catalysts were characterized by X-ray diffraction, N2 sorption, H2 temperature-programmed reduction, NH3 temperature-programmed desorption and NO temperature-programmed desorption techniques. It was shown that WO3 existed as amorphous species in the CZW. Introduction of WO3 in the CZW dramatically enhanced its surface acidity and gave rise to strongly adsorbed NO species, consequently increasing the catalytic activity. In addition, appropriate amounts of WO3 also increased the surface area and improved the reduction behavior of the catalyst. Compared to the CeO2-ZrO2, the CZW with 20% WO3 not only exhibited high resistivity to SO2, but also had a wider reaction temperature window. It showed a NOx conversion of> 90% at the space velocity of 60 000 h-1 in the temperature range of 200~463 ℃.
Abstract: The hydrodesulfurization of dibenzothiophene over physically separated Ni2P//MoS2 catalyst beds was investigated.The results indicated that the hydrogen spillover effect appears between the Ni2P/Al2O3 and MoS2/Al2O3 catalysts in the hydrodesulfurization reaction, which can significantly enhance the concentration of active sites and the hydrodesulfurization rate over the MoS2 catalyst. The spillover factor on Ni2P//MoS2is slightly higher than that on NiSx//MoS2, due to the higher hydrogen dissociation activity of Ni2P; as a result, Ni2P is a superior promoter to NiSx for the MoS2 catalyst.
Abstract: The supported Ni2P/MCM-41 catalyst was prepared by a solvothermal method using triphenylphosphine (TPP) as a cheap phosphorus material and tri-n-octylamine (TOA) as the coordinating liquid reaction system. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption, CO uptake, X-ray photoelectronspectroscopy (XPS) and transmission electron microscopy (TEM). The solvothermal synthesis was performed at atmospheric pressure and 330 ℃, at least 300 ℃ lower than the temperature for preparing the corresponding catalysts by temperature-programmed reduction (H2-TPR) method. The structure and hydrodesulfurization (HDS) performance of the as-prepared Ni2P/MCM-41 catalyst are compared with those prepared by H2-TPR, with dibenzothiophene (DBT) as a model compound. The results showed that the solvothermal method can decrease the aggregation of P species on the catalyst surface so as to achieve a Ni2P catalyst with high surface area (690 m2/g) and then promote the formation of small and highly dispersed Ni2P active phase. The catalyst from solvothermal synthesis exhibits distinctly a superior HDS performance to that prepared by H2-TPR method. Under the conditions of 340 ℃, 3.0 MPa, a H2/oil volume ratio of 500(volume ratio), and a weight hourly space velocity (WHSV) of 2.0 h-1, the conversion of DBT reaches 96.8% over the catalyst from solvothermal synthesis, which is 10.6% higher than that over the catalyst prepared via H2-TPR.
Abstract: The MCM-41 and Co-MCM-41 molecular sieves, prepared by hydrothermal synthesis method, were characterized with X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), nitrogen adsorption and NH3-TPD. The effects of aging time, crystallization temperature, crystallization time on the crystallization process of MCM-41 and Co-MCM-41 molecular sieves were investigated. The optimal conditions were as follows: 1 h of aging time, 110 ℃ of crystallization temperature and 2 d of crystallization time. XRD and FT-IR results indicated that Co was introduced into the framework of MCM-41. Brunauer-Emmett-Teller (BET) surface area and pore volume of MCM-41 and Co-MCM-41 were 986.42 m2/g, 637.69 m2/g, 0.762 1 m3/g and 0.537 2 m3/g respectively. The average pore diameter was 2.82 nm for both of MCM-41 and Co-MCM-41. The results of TPD showed that although MCM-41 and Co-MCM-41 possessed weak acidity, the acidity of Co-MCM-41 was stronger than MCM-41. Denitrification of model fuels containing about 1 737.35 μg(nitrogen)/g (16.03 mg(quinoline)/g) was studied over the synthesized MCM-41 and Co-MCM-41 with static adsorption at ambient conditions. The molecular size of quinoline, calculated by using density functional theory (DFT), was 0.711 6 nm×0.500 2 nm, implying that the quinoline easily access to the mesopores of MCM-41 and Co-MCM-41. The removal rate of basic nitrogen by Co-MCM-41 was clearly higher than MCM-41 due to its strong acidity and chemisorption between Co-MCM-41 and quinoline. Furthermore, Co-MCM-41 could be easily regenerated.
Abstract: Zn-based sorbents were prepared by uploading ZnO particles on different carbon materials (activated carbon, lignite semi-coke, bituminous semi-coke and lignite coke) using high-pressure impregnation under ultrasound-assistance. The physical properties, loading amounts of metal components and desulfurization performances were characterized by BET, XRD, SEM and fixed-bed reactor, respectively. The results show that the high-pressure impregnation under ultrasound-assistance method has a great improvement on the physical structures of carbon-based supports, and the BET surface area of sorbent prepared by lignite semi-coke support increases by 11 times. The type of carbon support affects the desulfurization behavior through the loading and the uniform dispersion of active component on support. The higher availability of active component and abundant pore structures result in a good desulfurization performance for Zn/LSC sorbent, having the maximum desulfurization efficiency, sulfur capacity and breakthrough time of 99.99%, 5.17% and 11.0 h, respectively. The lignite semi-coke is much easier than other carbon-based materials to be modified, and could be well used as support materials for hydrothermally synthesizing sorbent by high-pressure impregnation under ultrasound-assistance.
Abstract: A novel Bi2WO6/SC photo-catalyst was synthesized by hydrothermal method with semi-coke (SC) as the support. The as-prepared catalyst was characterized by SEM, BET, XRD, FT-IR and UV-vis diffuse reflectance spectra; its photo-catalytic activity in NO oxidation under visible light irradiation (λ> 400 nm) was evaluated. The results indicate that Bi2WO6 obtained by hydrothermal method displays micro-flower structure and absorption spectrum toward the visible light region above 400 nm. The Bi2WO6/SC catalyst exhibits excellent photo-catalytic activity in NO removal; NO conversion remains higher than 70% after reaction under irradiation for 4 h.
Abstract: A series of CaO-Al2O3 composites with different CaO contents were prepared by co-precipitation from low-price Ca and Al precursors, and characterized by XRD, TG-DTG, N2 adsorption, SEM and etc. Their performance removing HCl from reformate was evaluated by dynamic absorption method. Due to its large surface area, uniform particle size and high porosity, CAO-1 showed the best dechlorination performance. When the initial content of chlorine in reformate is less than 15 ng/μL, the dechlorination capacity can reach to 18% at a LHSV of 3 h-1 at 55 ℃.
Abstract: Using cheap raw materials, ZSM-5 zeolites with different morphology were hydrothermally synthesized by adding urea and adjusting alkalinity in initial solutions. The effects of zeolite morphology on the catalytic performance in methanol to propylene reactions were studied. The results show that the contents of urea and alkalinity have a great effect on the crystal morphology and growth directions. Specifically, ZSM-5 crystal shows the slowest growth rate along b-axis direction and the crystals of product appear as flakes of about 130 nm in thickness when urea/SiO2(mol ratio)=0.28 and Na2O/SiO2(mol ratio)=0.035. As the content of alkalinity increases within a certain range, the products gradually convert to the congeries of nano-size particles. The characterizations of ICP, NH3-TPD, and N2-adsorption show that the SiO2/Al2O3 mol ratios, acidity, and pore structures for all the products are much near to each other. The products of flake shape show many advantages in catalytic reactions: good selectivity in methanol to propylene conversions, high over 60% of olefin (ethylene + propylene), about 8.4 of propylene/ethylene ratio, and superior catalytic stability, being over 95% of methanol conversion for 200 h continuous reaction. The excellent performance may be attributed to the short diffusion path length along b-axis direction and high crystallinity.
Abstract: By using the droplet size meter, the growth of fine particulates of typical coal ash components, including quartz, ferric oxide, calcium sulphate and mullite, was investigated in supersaturated water environment. The supersaturated water vapor environment was built through the contact of hot water with cold air. The results show that the fine particulates with good wettability grow easily; the smaller the initial particle, the fast it grows. The temperature of hot water has a great influence on the growth of particulates; higher temperature is favorable to form larger particulates. Overall, the diameter of particulates with different physical and chemical properties can be increased to 1 to 6.6 times larger at low supersaturation.
Abstract: A series of CeO2/Co3O4 composite oxygen carriers with different CeO2 loadings were prepared and characterized by XRD and H2-TPR. The performance of CeO2/Co3O4 as an oxygen carrier in methane chemical looping combustion was investigated in a fixed-bed reactor by temperature-programmed and isothermal reactions; the effect of CeO2 loading on the structure, activity and selectivity of the oxygen carrier was considered in detail. The results show that the addition of CeO2 can reduce the reaction temperature and increase the effective reaction time of the CeO2/Co3O4 oxygen carriers for methane oxidation. However, loading of excessive CeO2 may promote the partial oxidation of methane forming CO and H2 and leads to a decrease in the selectivity to CO2. The CeO2/Co3O4 composite oxygen carrier with a CeO2 loading of 30% (mol ratio) exhibits the highest activity and redox stability in the chemical looping combustion of methane; over it, methane can be quickly converted to CO2 and H2O with high selectivity (over 90%) at 650 ℃ and the reduced oxygen carrier can be fully recovered in O2 atmosphere. Moreover, no obvious decline in the conversion of methane and selectivity to CO2 is observed in the successive CH4-reduction and O2-oxidation redox process for over 20 cycles.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
