Abstract: The Fe/Al-SiO2 composite metal oxides were prepared by various methods to simulate the composition of red mud. A series of experiments were carried out to study the mercury removal performance from simulated flue gas. The results show that the composite metal oxide obtained by sol-gel method has an excellent mercury removal performance in a temperature range of 300-450 ℃. Among them, average mercury removal efficiency can reach 94.8% within 3 h at 350 ℃. Fe2O3 provides lattice oxygen and chemical adsorbed oxygen for the oxidation of Hg0, and SiO2 is conducive to the dispersion of the active component Fe2O3, which enhances the contact between Hg0 and the active sites. In the presence of trace HCl and NO in flue gas, the removal efficiency of Hg0 is close to 100%. However, the average mercury removal efficiency reduces to 90.7% and 53.4% respectively after adding 0.2 mL/min and 0.4 mL/min SO2, since the reaction of SO2 and Fe2O3 produces Fe2(SO4)3, leading to the deactivation of Fe2O3.
Abstract: Direct coal liquefaction residue (DCLR) was swelled by four kinds of ionic liquids with the same anion and different organic chain length cations, [EMIM] [MeSO4], [BMIM] [MeSO4], [HMIM] [MeSO4] and[OMIM] [MeSO4], and the effects of swelling treatment with ionic liquids on swelling degree, surface morphology, functional group distribution, the main structure and pyrolysis performance of the direct coal liquefaction residue were analyzed by SEM, FT-IR and TG-DTG characterizations. The swelling results show that different chain length ionic liquid has different swelling degrees for the DCLR, and[HMIM] [MeSO4] presents the best swelling effect with the swelling degree of 1.78. The FT-IR results indicate that the ionic liquid could destroy C-H bond in DCLR, leading to a change in relative content of aliphatic and aromatic compounds. The TG-DTG characterization demonstrates that the pyrolysis performance of the residue is greatly affected by the different organic chain length ionic liquid. And the[OMIM] [MeSO4] ionic liquid is more favorable for the pyrolysis of the residue than others, with the weight loss rate of 47.5%. However, the pyrolysis performance of the residue is restrained by the[BMIM] [MeSO4] ionic liquid, in which the weight loss rate is lower than that of DCLR (without swelling treatment). The pyrolysis kinetic data based on Coats-Redfern method show that the pyrolysis reaction for the direct coal liquid residue and the swelled ones at low temperature (180-480 ℃) obeys a second order law, while the third and fourth order law of reaction is more suitable for the residue pyrolysis at high temperature section (480-825 ℃). In addition, the activation energy of the pyrolysis process for the DCLR is altered obviously by swelling treatment with different organic length ionic liquid, the longer the chain length, the higher the pyrolysis activation energy.
Abstract: In order to strengthen tar destruction and hydrogen-rich gas production in the biomass gasification, a novel decoupled dual loop gasification (DDLG) system was proposed. The system decouples gasification process into fuel gasification, tar reforming and residual char combustion, which occur in three independent reactors, i.e. gasifier, reformer and combustor. Both the gasifier and the reformer are separately interconnected with the combustor, forming two circulation loops in parallel. With pine sawdust as feedstock, and calcined olivine as both solid heat carriers and in-situ tar destruction catalyst, the performance of biomass gasification was investigated. The results indicate that the reforming after the gasifier and the presence of olivine catalyst greatly improve the tar destruction. Specifically, at the gasifier temperature of 700 ℃, the reformer temperature of 850 ℃ and the steam to carbon mass ratio (S/C) of 1.2, the tar content in product gas decreases to 13.9 g/m3, and the dry gas yield and H2 concentration reach 1.0 m3/kg, and 38.8%, respectively.
Abstract: Density functional theory method was used to calculate the bond dissociation energies of the Caromatic-Cα, Cα-Cβ, Cβ-O bond, and Caromatic-O bonds in four lignin dimer model compounds, viz., (2-(2-methoxyphenoxy)-1-phenylethan-1-ol, 2-(2-methoxyphenoxy)-1-phenylethan-1-one, 1-methoxy-2-(2-methoxy-2-phenylethoxy)benzene, and 2-(2-methoxyphenoxy)-1-phenylethyl acetate; the homolytic cracking reaction during pyrolysis of these dimers was then invetigated and the formation pathways of pyrolysis products of different dimers were analyzed. The results show that the homogenization of Cβ-O bond is the main reaction in the initial pyrolysis of dimer, whereas the homolysis of Cα-Cβ bond is a competitive reaction. After the oxidation and acetylation of Cα-OH, the bond dissociation energy of Cβ-O bond decreases, whereas the dissociation energy of Cα-Cβ bond increases, ccompanied with an increase in the probability of the Cβ-O bond dissociation and a decrease in the competitive ability of Cα-Cβ bond homolysis. For the pyrolysis of four model compounds, the main aromatic products include benzyl alcohol, toluene, benzaldehyde, guaiacol, etc. The selective modification of the Cα-OH functional groups can regulate the types of pyrolysis products. In particular, the product types for the pyrolysis of model compounds modified by oxidation become less, accompanied with an increase in the selectivity to ceratin products. Ethylbenzene and toluene can be produced from the hydrolysis of dimers modified by methylation and acetylation.
Abstract: The PdMoP/γ-Al2O3 catalyst was prepraed through loading the Pd, Mo, and P elements on the γ-Al2O3 support by incipient impregnation method and characterized by XRD, NH3-TPD, XPS, Py-FTIR, nitrogen physisorption and STEM-EDS. The catalytic performance of PdMoP/γ-Al2O3 in the hydrodeoxygenation of soybean oil methyl ester to alkane biodiesel was invetigqated and the operation conditions were optimized. The results show that a combination of Pd, Mo and P elements can effectively adjust the catalyst acidity; Mo can reduce strong acidity, whereads P can enhance weak acidity, leading to a decrease in the B/L ratio of weak acid sites and a slight increase in the B/L ratio of strong acid sites. The optimized hydrodeoxygenation conditions are 315 ℃, 1.5 MPa, WHSV=0.5 h-1, and V(hydrogen)/V(esters)=1100; under such conditions, the conversion of soybean oil methyl esters reaches 98.4% and the C15-18 alkane yield is 91.5%.
Abstract: NiMoP(x)/Al2O3 catalysts with different ethylene glycol (EG) contents were prepared by impregnating NiMoP solution containing EG into Al2O3. The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) performances of the catalysts were evaluated using dibenzothiophene (DBT) and quinoline (Q) as the model compounds. The results showed that the HDS and HDN performances of the catalysts could be improved by adding of EG when the amount of EG was low (nEG/nNi ratio value was 0, 0.5, 1, 2, 3, respectively), and the improvement of HDN performance was more obvious than HDS performance. With the increase of EG content, the activity of HDS and HDN of the catalysts was further improved. TEM and XPS analysis showed that EG was helpful to increase the stacking layer number and lamellar length of MoS2 particles in the catalysts, and with the increase of EG content, the stacking layer number and lamellar length of MoS2 particles increased. EG could improve the surface atomic concentration of Mo, but practically had no influence on the surface atomic distribution of Ni. However, EG significantly increased the sulfuration degree of Mo and Ni. TG characterization showed that EG interacted with alumina and metal active components in various ways, and there were high temperature resistant organic species interacting with active components.
Abstract: ZSM-5 zeolites with different framework Al (AlF) siting were hydrothermally synthesized by adding mineralizer, urea, or by changing the silicon source. The morphology, textural properties, AlF siting, and acidity of different ZSM-5 zeolites were characterized using SEM, XRD, BET, XRF, MAS NMR, NH3-TPD, and Py-IR. Furthermore, the conversion of methanol to aromatics (MTA) was used to investigate the catalytic performance of different catalysts.The results suggested that different ZSM-5 zeolites were highly crystalline with a uniform morphology, but there were large differences in AlF siting and acidity. The AlF in the ellipsoidal ZSM-5 sample was mainly distributed in straight or sinusoidal channels and displayed more acidic sites. AlF of bulk ZSM-5 was mainly located at the intersection of channels, and it showed the lowest amount of strong acid sites. The ellipsoidal ZSM-5 catalyst in which AlF was mainly located in straight or sinusoidal channels exhibited more acidic sites and higher stability and aromatic selectivity during the MTA reaction.
Abstract: A series of hierarchical isomorphically Fe-substituted porous beta zeolites (BEAs) was synthesised in a one-step process via soft-template approach (nFe-HBeta, n=Fe/Al) and a series of Ni-based catalysts (10Ni/nFe-HBeta) was prepared by equal volume impregnation. The results showed that the nFe-HBeta zeolites possessed a sheet-like structure with a high crystallinity and numerous porous channels. The introduction of the heterogeneous iron atoms could reduce the degree of order of the mesoporous phase and decrease the size of the zeolite particles and the number of moderate and strong acidic sites. For the 10Ni/nFe-HBeta catalyst, a synergistic effect existed between the framework iron and NiO species, which could enhance the interaction between the active Ni and HBeta support, increase the dispersion of the active metal Ni, and reduce the NiO particle size. In the ethanol steam reforming (ESR) reaction, Fe introduction could inhibit the ethanol dehydration reaction through the shielding of acidic sites and could promote the steam reforming reaction of CO and CH4, effectively improving the H2 selectivity. Among the Fe-containing catalysts, 10Ni/0.15Fe-HBeta showed a H2 selectivity of up to 72.15% and an ethanol conversion rate of 99.6% at 500 ℃, while the amount of coke deposition was only 4.3% after a 12 h reaction.
Abstract: Al2O3 supported Pt and Pd nanoparticle catalysts were prepared by impregnation-reduction method, and employed in the photocatalytic aqueous-phase reforming of ethylene glycol. Light illumination can decrease the reaction activation energy remarkably. Pt/Al2O3 exhibits much higher H2 turnover frequency (TOF) and lower CO selectivity than Pd/Al2O3 catalyst. Their morphology and structure were characterized by XRD, TEM, UV-vis techniques. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicates light can promote the cleavage of O-H bonds of ethylene glycol molecule. DFT calculation suggests the lower CO selectivity over Pt/Al2O3 catalyst can be attributed to the low energy barriers of reaction in the step of CO+O→CO2.
Abstract: Siderite, rich in the transition elements, is an idea material to prepare the catalysts for the selective catalytic reduction (SCR) of NOx by NH3. In this work, siderite was doped with Mn and Ce and the performance of Mn-Ce co-doped siderite catalysts in the removal of NOx (de-NOx) by SCR with NH3 was then investigated. The results illustrate that FeCO3 as the main component of siderite can be converted into Fe2O3 by calcination at 450℃. The doping of siderite with Mn and Ce can enhance the surface area and acidity of siderite and reduce the thermal stability of ammonium sulfate formed on the catalyst surface. As a result, the Mn-Ce co-doped siderite catalysts exhibit high efficiency in the de-NOx by SCR and high resistance against sulfur. Over the 3%Mn1%Ce-siderite catalyst, high NOx conversion (>90%) is achieved in the temperature window of 180-300℃; moreover, the NOx conversion remains above 75% even after introducing SO2 for 7.5 h.
Abstract: Ethyl methyl carbonate (EMC) has been widely used as a solvent in electrolyte of lithium-ion batteries due to its outstanding physico-chemical properties. The transesterification method has been industrially applied to produce EMC owing to its excellent efficiency, simple synthesis processing and high product purity. This article systematically reviewed the advances in EMC synthesis via the transesterification approach, including the thermodynamics, kinetics, homogeneous and heterogeneous catalysts, reaction mechanism and reaction engineering, particularly focusing on new progress in the last five years. For homogeneous catalysts, the relationship between alkali strength and catalytic efficiency was discussed based on pKb (alkalinity coefficient). The effects of different anion and cation structures on the catalytic performances of imidazole ionic liquids were also investigated. A possible deactivation mechanism of the sodium methoxide catalyst, which was widely applied in manufacture, was proposed. The effects of different preparation methods, surface acidity and basicity of heterogeneous catalysts on catalytic efficiency were critically reviewed and discussed. The advantages and disadvantages of as-reported catalysts with various types were carefully compared. The future studies should focus on the solid base catalyst with higher efficiency and three-phase catalytic distillation technology.
Abstract: With CNT@TiO2 prepared by sol-gel method as the support, the PtCo-CNT@TiO2 composite was prepared by electro-deposition and used as the anode catalyst for direct methanol fuel cells. The PtCo-CNT@TiO2 composite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical workstation. The results show that the PtCo-CNT@TiO2 composite displays significant crystals and the metal particles surround the TiO2-coated carbon nanotubes; when used as the anode catalyst for direct methanol fuel cells, it exhibits high activity and stability. The PtCo-CNT@TiO2 catalyst has an electrochemical surface area of 164 m2/g and the oxidation peak current of methanol reaches 45 mA/cm2 at 65 ℃; after 300 s, the oxidation current tends to be 24 mA/cm2 and the oxidation peak current of methanol under alkaline conditions is 39.7 mA/cm2.
Abstract: For developing metal organic frameworks (MOFs) suitable for the storage of nature gas by adsorption, the MIL-101 (Cr) sample was synthesized by solvothermal method, with which the characterization by adsorption of nitrogen at 77.15 K and the adsorption equilibrium and charge/discharge of methane were conducted. The adsorption equilibrium data of methane on the sample were measured volumetrically at temperature range of 293-313 K within a pressure range of 0-100 kPa and 0-7 MPa, respectively. The limit isosteric heat of adsorption was determined by employing the Henry's law using the adsorption data at very low pressure region, and the absolute adsorption amounts of methane on the sample were determined via nonlinear fit of the adsorption data at high pressure range by using Toth's equation. Isosteric heats of methane adsorption were then calculated through Clausius-Clapeyron equation and Toth's potential function. The charge and discharge tests of methane were performed at a flow rate range of 10-30 L/min on a 3.2 L conformable vessel packed with samples about 940 g. The results show that the mean limit isosteric heat is 23.89 kJ/mol, and the average relative error of the result predicted by the Toth equation is about 1.06%. The mean isosteric heat of adsorption determined by Clausius-Clapeyron equation and Toth's potential function is about 15.51 kJ/mol and 13.56 kJ/mol, respectively. The results also reveal that the total amount of charge/discharge at the flow rate of 10 L/min and 30 L/min is about 347 L/338 L and 341 L/318 L, respectively, which are in correspondence with the ratios of discharge about 98.3% and 94.1%. It suggests that the isosteric heat of methane adsorption determined by Clausius-Clapeyron equation is more reasonable for practical applications, and slower charging/discharging with a smaller flow rate is beneficial to increasing the total amount of charge/discharge and the discharging of the adsorbent bed.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
