Abstract: A series of KNiMo-based catalysts were prepared by using non-thermal plasma and characterized by XRD, nitrogen sorption, TEM, H2-TPD, CO-TPD, and in-situ CO adsorption DRIFTS; their catalytic performance in the higher alcohol synthesis (HAS) from syngas was investigated. The results indicate that in comparison with those prepared by the conventional thermal method, the KNiMo-based catalysts prepared by using non-thermal plasma display thinner and shorter MoS2 slabs and more highly dispersed and coordinatively unsaturated sites, which endow the KNiMo-based catalysts excellent performance in HAS. In particular, for the HAS over the KNiMo-DPS catalyst under 350 ℃, 5 MPa, and a gas hourly space velocity (GHSV) of 5000 h-1, the conversion of CO reaches 32.3%, with a selectivity of 75.1% to total alcohol and a C2+ alcohol selectivity of 65.2% in the total alcohols.
Abstract: Three catalysts, CuO-CeO2 (5:1 molar ratio), CuO-ZnO (5:4 molar ratio) and CuO-ZnO-CeO2 (5:4:1 molar ratio), were prepared by coprecipitation method.The physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), hydrogen temperature reduction (H2-TPR), CO2 temperature programmed desorption (CO2-TPD), nitrogen adsorption desorption, X-ray photoelectron spectroscopy (XPS), N2O titration.The activity of the catalyst was evaluated in a catalytic microreactor.The results show that, the physicochemical properties and catalytic activity of the ternary CuO-ZnO-CeO2 catalyst are different from that of the binary catalyst, specifically, the strength of surface alkaline sites are increased, the thermal stability is enhanced, the particle size of CuO particles is reduced, the dispersion of copper and the concentration of oxygen vacancies are increased, and the catalytic activity is finally improved. In the CuO-ZnO-CeO2 catalyst, the CuO particle size is 8.2nm, the specific surface area of copper is 68.4m2/g, the copper dispersion is 7.19%, the selectivity and the yield of methanol are 48.6% and 0.057mmol/(g·min), respectively.
Abstract: A series of CuZnAl catalysts were prepared by the complete liquid-phase method with different heat treatment times and characterized by XPS, XRD, H2-TPR, NH3-TPD-MS and N2 adsorption-desorption; their catalytic performances in the synthesis of higher alcohols from syngas were investigated in a slurry bed reactor. The results indicate that an increase in the heat treatment time can enhance the interaction between the Cu and Al species and alter the amount of Cu+ species over the CuZnAl catalysts, influencing the synergistic effect of Cu+-Cu0 sites. In addition, with the increase of heat treatment time, the surface acidity of CuZnAl catalyst decreases, accompanying with an increase in the pore volume and pore size; small amount of surface weak acid sites, large pore volume and large pore size are beneficial to the formation of higher alcohols. The CuZnAl catalyst obtained by heat-treating for 7 h exhibits excellent performance in the synthesis of higher alcohols, with a CO conversion of 38.1% and a higher alcohols mass fraction of 65.9% in the total alcohols.
Abstract: Al2O3 nano-sheet (Al2O3-CN) was synthesized under hydrothermal condition. The cobalt-based catalyst of 20% (mass fraction) was prepared by impregnation method and applied to Fischer-Tropsch synthesis. The Al2O3-CN (226 m2/g) and commercial alumina (Al2O3-C, 249 m2/g) have similar specific surface area, but Al2O3-CN has more narrow pore size distribution. Compared with Co/Al2O3-C catalyst, Co/Al2O3-CN catalyst showed higher reduction degree and more uniform cobalt particle size distribution after impregnation. Thus, Co/Al2O3-CN catalyst exhibited higher CO conversion and lower methane selectivity. In order to further improve the catalytic performance of Co/Al2O3-CN, Al2O3-CN was modified with ZrO2. The characterization results showed that with the increase of ZrO2, the specific surface of Al2O3-CN did not change significantly, and the pore volume and pore diameter increased. The cobalt particle size decreased and the number of active sites increased. Under the same reaction conditions, the CO conversion rate of catalysts modifield by ZrO2 was farther improved and selectivity of methane was decreased.
Abstract: Ni-Al2O3 catalyst was prepared by hydrothermal deposition method and used in the reaction of CO2-CH4 reforming. The effect of reaction time, temperature, CO2/CH4 ratio and feed space velocity on the carbonaceous deposition on the Ni-Al2O3 catalyst surface in CO2-CH4 reforming was investigated, on the basis of temperature-programmed hydrogenation (TPH) characterization. The results indicate that the carbonaceous deposition is an important factor for the deactivation of Ni-Al2O3 catalyst in CO2-CH4 reforming. The amount of deposited carbon increases with the prolongation of reaction time; meanwhile, the hydrogenation peak in the TPH profiles shifts towards higher temperature, indicating that the graphitization degree of the deposited carbon also increases with prolonging the reaction time. The reaction temperature and feed space velocity, especially the later one, also have an influence on the carbon deposition. In addition, due to the carbon elimination reaction by CO2 (CO2+C=2CO), the ratio of CO2/CH4 in the feed shows a great influence on the type and amount of carbon deposited on the Ni-Al2O3 catalyst. A low CO2/CH4 ratio may not achieve a significant inhibition on the coke formation; with the increase of CO2/CH4 ratio, the carbon deposition can then be increasingly inhibited; however, a higher CO2/CH4 ratio also means higher cost for CO2 separation and recovery in the product.
Abstract: Co/SEP and Co-Ce/SEP catalysts were prepared by chemical precipitation method with sepiolite (SEP) as support. X-ray diffraction (XRD), H2-programmed reduction (H2-TPR) and transmission electron microscopy (TEM) were used to characterize the catalysts. It is proved that the addition of Ce significantly improved the dispersion and reducibility of the catalyst. The effects of Ce addition, reaction time, reaction temperature and steam/carbon (S/C) ratio on hydrogen production were investigated. The results show that the ethanol conversion and hydrogen production of Co-Ce/SEP are the highest values, 85% and 65%, respectively, when the WHSV is 20.5 h-1, the S/C ratio is 3 and the reaction temperature is 600℃. Meanwhile, the addition of Ce can make Co-Ce/SEP possess superior activity and stability.
Abstract: The hydrogen production by methane/steam reforming at atmospheric pressure was investigated by using a self-made dielectric barrier discharge experimental system.The effect of water/carbon ratio (steam/methane molar ratio), total gas flow, discharge voltage and discharge frequency on the methane conversion, hydrogen and other major product yields was examined.The experimental results show that the methane conversion rate and hydrogen yield increase with the increase of water carbon ratio and discharge voltage, and the methane conversion rate and hydrogen yield increase first and then decrease with the increase of total gas flow rate and discharge frequency. The maximum hydrogen yield (14.38%) can be obtained at the discharge voltage of 18.6 kV, discharge frequency of 9.8 kHz, water/carbon ratio of 3.4, and total reaction gas flow rate of 79 mL/min. In addition, The active group in the discharge process was diagnosed by in-situ emission spectroscopy, and the changing trend in the spectral signal intensity of CH·, OH·, H2 and Hα active particles with the experimental parameters was obtained. The possible generation path of hydrogen is predicted by combining with the discharge mechanism.
Abstract: Herein, a new superfine nano Pd/Ni-Mo2C (2-6 nm) catalyst is developed via a facile, alkali-induced self-assembly strategy. The catalyst exhibits excellent performance towards ethanol electro-catalytic oxidation in alkaline system, with an activity of 2832.2 mA/mgPd and a residual current density of 447.8 mA/mgPd, which is 2.6 and 4.7 times enhancements compared with the commercial 10% Pt/C catalyst (1107.6 and 96.1 mA/mgPd).
Abstract: A series of bismuth oxybromide photocatalysts were fabricated via a one-step hydrothermal method through pH value adjustment. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence spectroscopy (PL). The photocatalytic activities of the as-prepared samples were examined by degradation of Rhodamine B (RhB), methyl orange (MO) and phenol. The results indicate that the B9 displayed the highest photocatalytic activities. The enhanced photocatalytic activity can be attribute to enhanced absorption in the visible region and the decreased recombination efficiency of photogenerated charge carriers. The effect of hydrothermal pH value on the composition and morphology was explored and a synthesis process of bismuth oxybromide was proposed.
Abstract: A series of Ag/CeO2-Co3O4 catalysts with various Ce/Co ratios were prepared by co-precipitation method and employed in the low-temperature oxidation of formaldehyde. The results demonstrate that the Ag/CeO2-Co3O4 catalysts exhibit excellent performance in the oxidation of formaldehyde and the Ce/Co ratio has a significant impact on the catalytic performance. The XRD, nitrogen adsorption-desorption, Raman spectroscopy, H2-TPR and in-situ DRIFTS results illustrate that with the increase of Co content in Ag/CeO2-Co3O4, the pore volume increases whereas the surface area decreases. The presence of CeO2 is beneficial to enhancing the redox ability and increasing the oxygen vacancies and Co2+ species, which can promote the activation of oxygen species and then the degradation of formaldehyde. According to the in-situ DRIFTS results, the decomposition of formates on the catalyst surface is probably the rate-determining step for the degradation of formaldehyde at low temperature.
Abstract: A series of supported CuxMn1-xCe0.75Zr0.25/TiO2 (x = 1.0, 0.75, 0.5, 0.25, 0) catalysts were prepared by impregnation and characterized by XRD, H2-TPR, O2-TPD and XPS; the performance of CuxMn1-xCe0.75Zr0.25/TiO2 catalysts in the degradation of toluene coupled with low temperature plasma under high space velocity was then investigated. The results indicate that the composite catalysts with single Cu or Mn as the main active component exhibit higher activity than those with double Cu and Mn components; the addition of second component may weaken the interaction between Cu and Ce, leading to a decrease in the content of lattice oxygen and the reducibility at low temperature. The CuCe0.75Zr0.25/TiO2 catalyst exhibits superior performance for toluene oxidation in the initial reaction stage, owing to its high content of lattice oxygen and oxygen vacancies. With the increase of the specific energy density (SED) of low temperature plasma, the concentration of O3 increases and the MnCe0.75Zr0.25/TiO2 catalyst then displays higher activity in toluene degradation than CuCe0.75Zr0.25/TiO2, because of the prominent enhancement of synergistic effect between plasma and catalyst over the former MnCe0.75Zr0.25/TiO2 catalyst.
Abstract: The conversion of sweet sorghum stalk juice rich in sucrose, glucose and fructose to furan compounds (5-hydroxymethylfurfural or furfural) was investigated over Hβ zeolite in γ-butyrolactone solvent. The results indicated that the main product for the conversion of sweet sorghum stalk juice (SSSJ) was 5-hydroxymethylfurfural; however, high yield of furfural was obtained in the conversion of model sweet sorghum stalk juice (MSSSJ) containing the same amount of hexose under the same conditions. The 27Al MAS NMR results showed that ion-exchange took place between the Hβ zeolite and alkaline ions (mainly potassium) in the sweet sorghum stalk juice, resulting in the transformation of octahedrally coordinated aluminum into tetrahedrally coordinated framework aluminum. As an appropriate configuration environment of aluminum for Hβ was necessary for the formation of furfural from hexose, high yield of 5-hydroxymethylfurfural was achieved for the conversion of sweet sorghum stalk juice (SSSJ) due to the ion-exchange of Hβ with alkaline ions.
Abstract: The experiments of sewage sludge (SS) co-pyrolysis with four kinds of plastics (PE, PP, PS and PVC) were carried out in a high temperature tubular furnace to obtain four kinds of biochar (SSCPE, SSCPP, SSCPS and SSCPVC), respectively. The contents, residual rates, BCR speciation, leaching toxicity and potential ecological risk assessment of heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd and Pb) in biochar were studied. The results show that the residues of heavy metals except Cd are reduced by adding different kinds of plastics during SS pyrolysis. Compared with the biochar (SSC) obtained by SS pyrolysis, the addition of PE, PP and PS can promote the transformation of heavy metals speciation in biochar to more stable fractions (F3+F4) and achieve the immobilization of heavy metals. The addition of PVC only promotes the immobilization of Cr and As in biochar, while exhibiting an obvious activation effect on other heavy metals. The concentrations of leaching heavy metals in four kinds of biochar are lower than the limit value of the identification standard for extraction (GB5085.3-2007), and the potential ecological risks of the four kinds of biochar are all in a slight level. This work provides a good theoretical support for the process of the cooperative disposal of SS and waste plastics.
Abstract: The MoP/SiO2 catalyst was prepared from the supported Mo phosphate by the H2-TPR method and treated with 3%H2S/H2 at different temperatures. The as-prepared catalysts were characterized by means of XRD, HRTEM-EDX, XPS, NH3-TPD, ICP-AES and CO chemisorption and tested for the thioetherification of isoprene and n-butylmercaptan. The effects of sulfuration temperature on the MoP/SiO2 catalyst structure and thioetherification performance were investigated. The results showed that the MoP phase was still stable even at the sulfuration temperature of 400 ℃. As the sulfuration temperature increased, the acid amount of the catalysts increased while the surface metal site density decreased. As a result, in the thioetherification of isoprene and n-butylmercaptan, the C-S bond hydrogenolysis and the over-hydrogenation of isoprene were suppressed on the sulfurized catalysts, while the olefin polymerization was promoted. Relatively, the MoP/SiO2 catalyst sulfurized at 120 ℃ had better performance for the thioetherification and the selective hydrogenation of isoprene.
Abstract: A series of dispersed nano molybdenum disulfide (MoS2) catalysts were prepared with molybdenum dialkyl dithiocarbamate (Mo-DTC) and molybdenum hexacarbonyl (Mo(CO)6) as the precursors by hydrothermal methods and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (NH3-TPD). By using a simulated oil slurry containing three kinds of olefins (octane, styrene and trans-dibenzylethene), benzothiophene and anthracene, the catalytic performance of nano MoS2 in the hydrogenation was investigated, with the help of gas chromatography-mass spectrometry (GC-MS). The results indicate that all the prepared catalysts are in the form of 2H-MoS2; however, their crystallinity, particle size, vulcanization degree, and acid property are influenced by the pretreatment conditions; the preferred vulcanization conditions for the Mo-DTC-and Mo(CO)6-based MoS2 catalysts are 380 ℃/30 min and 370 ℃/30 min, respectively, to achieve a relatively high activity in the hydrogenation of olefins and benzothiophene. Over the Mo-DTC-based nano-MoS2 catalyst, the saturation conversion of olefins hydrogenation is 98.10% and the hydrodesulfurization rate is 94.51%, whereas the saturation conversion of anthracene hydrogenation is 29.47%, without forming octahydroanthracene (8HN) or perhydroanthracene. In contrast, the activity of Mo(CO)6-based nano-MoS2 catalyst is slightly lower, with the saturation conversion of olefins hydrogenation being 94.01% and the hydrodesulfurization rate being 89.01%; similarly, the saturation conversion for anthracene hydrogenation is 24.20%, without 8HN or perhydroanthracene in the product. As a whole, in comparison with the Mo(CO)6-based MoS2 catalyst, the nano MoS2 catalyst derived from Mo-DTC displays higher efficiency in both olefins saturation and sulfur-containing compounds desulfurization, and low degree hydrogenation of aromatic hydrocarbons; moreover, it also exhibits higher hydro-treating selectivity for the catalytic cracking slurry and higher stability during hydrogenation.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
