Abstract: The blended ash fusion characteristics and its fusion mechanism of biomasses (peanut husk (PH) and rice husk (RH)) and Changzhi (CZ) coal with high melting point (MP) were investigated by ash fusion temperature (AFT) detector, X-ray fluorescence, X-ray diffraction, and FactSage software. The results show that the AFTs of CZ ash mixtures decrease with addition of biomass ash, and the fluxing effect of PH ash is better than that of RH ash, which mainly depends on their ash chemical compositions and elements existing form. The formations of low MP minerals anorthite, albite, and leucite are responsible for the decrease in AFT of PH and CZ mixtures. With RH ash addition, feldspar and eutectics are generated, resulting in a decrease in AFT of their mixtures. In the presence of Na2O, CaO, or K2O, SiO2 and Al2O3 would firstly react with them to form low MP aluminosilicate from the perspective of thermodynamic calculation, inhibiting formation of high MP mullite. The mixed ash fusion process could be divided into two major stages:fusion of K-and Ca-bearing minerals, respectively.
Abstract: Barkinite, one of Chinese special maceral, was chosen to study its peculiar thermal characteristics based on thermogravimetric analysis and Rock-eval analysis by comparing vitrinite with bark coal. The changes of chemical structure by heat-treatment of barkinite were discussed by HRTEM. The distribution of functional group of barkinite was studied by Micro-FTIR method. The results show that barkinite has the highest mass loss and the maximum rate of mass loss among these three samples. Barkinite and vitrinite have both orientated layers after temperature above 350℃. With the increasing of temperature, the orientation in aromatic layer is obviously improved and some layers in stacks increase. At the same temperature, for barkinite and vitrinite, three fringes show the greatest abundance, namely, naphthalene, 2×2, and 3×3 fringes, following by 4×4 and 5×5 fringes. Barkinite has a higher abundance of naphthalene than vitrinite and has lower abundances of larger aromatic fringes than vitrinite, for instance, 3×3, 4×4, and 5×5 fringes. With the increasing of temperature, the content of naphthalene in barkinite and vitrinite is increased. Their abundance reaches the highest at 450℃ that is also the temperature of the maximum mass loss rate of barkinite, which indicates that the thermal characteristics of barkinite is related to the abundance of naphthalene in the chemical structure of barkinite.
Abstract: The occurrence modes and migration behavior of vanadium were investigated by sequential chemical extraction combined with ICP-OES during combustion of high-sulfur petroleum coke. The chemical reaction mechanism was discussed based on thermodynamic analysis. The vanadium in raw petroleum coke is mainly associated with organic matter and stable forms. With increasing temperature organic V disappear and the released vanadium could react with minerals such as Ca, K, Na, Fe to form different vanadium species including water soluble and ion exchange state, carbonates and Fe-Mn oxides. Steady-state vanadium is mainly combined with other minerals to form amorphous substance existing in petroleum coke. These amorphous substances might transform and release vanadium species at high combustion temperatures. The V volatility is correlated with temperature and burn out rate. The volatility may sharply rise because organic matter decomposed and released gaseous VO2 above 1100℃.
Abstract: Based on the horizontal tubular reactor-chemical absorption together with TG-FTIR-MS methods, release characteristics of corrosive gases, viz., HCl and H2S, during pyrolysis of refuse derived-fuels were investigated. The effects of pyrolysis temperature and pyrolysis type on their release behaviors for the aged (ARDF) and normal (NRDF) categories were compared. Meanwhile, the occurrence properties of corrosive elements (Cl and S) in solid products were also explored. The results indicate that the release of each corrosive gas has similar characteristic temperature range for slow pyrolysis of two categories. The release of HCl occurs at 200-400 and 420-500℃, respectively, while the emission of H2S is observed at 230-370 and 380-670℃, respectively. In addition, ARDF has a lower emission amounts of both HCl and H2S compared to NRDF under this condition. With regard to fast pyrolysis, the release of corrosive gases show different regularities, which largely depends on pyrolysis temperature. With increasing temperature, the emission of HCl and H2S present a nonlinear and an increasing trends, respectively, reaching peak values at 850℃; It is 48.8% (ARDF) and 29.4% (NRDF) for HCl, 6.8% (ARDF) and 44.6% (NRDF) for H2S. Subsequently, due to the distinctive release characteristics of corrosive gases, the occurrence of corrosive elements in solid phase relating to temperature differs in two categories. The retained amounts of Cl and S reach to 59.4% (450℃) and 84.3% (750℃) for ARDF, respectively. But for NRDF, that is 36.7% (850℃) and 15.2% (650℃), repetitively. It can be inferred that ARDF has the more stable corrosive elements difficult to be released into gases, which could provide some guidelines on thermal utilization of refuse derived-fuels.
Abstract: γ-Valerolactone (GVL), as a sustainable platform chemical, were produced through an aqueous phase hydrogenation of biomass-derived levulinic acid (LA) in the presence of supported ruthenium catalysts, in which the catalysts were prepared by solvent-free microwave-assisted thermolytic method. The effects of catalyst support, reaction media, pressure, temperature and LA initial concentration were investigated to obtain the optimum conditions for high γ-valerolactone yield. 5% Ru/AC catalyst exhibits a more superior catalytic performance compared with Ru/CNT, Ru/FCNT, Ru/γ-Al2O3-MW and Ru/γ-Al2O3-IM at 100℃ and 2.0 MPa of 0.10 g/mL LA concentration in water solution. This superior performance is attributed to the higher dispersion of metallic Ru over coconut shell activated carbon. GVL can be produced with a good yield of > 99% under optimum conditions, and has the potential to provide a green, renewable platform for biotransformation.
Abstract: Using montmorillonite (MMT), a natural layered clay, as the layered precursor, nanosheets of Ni/MMT are obtained via a facile method, in which the nickel components are introduced on to the surface of the exfoliated MMT nanosheets dispersed in water via deposition-precipitation with nickel nitrate and urea. Due to their unique properties originated from the two-dimensional (2D) structure, which favors mass transfer and diffusion of the aromatics and their hydrogenation products over the catalyst during reaction, the obtained nanosheets of Ni/Clay show higher efficient for hydrogenation of aromatics than Ni/SBA-15 and Ni/γ-Al2O3 catalysts. And the highest TOF for hydrogenation of tetralin over the nanosheets of Ni/Clay is obtained as nickel loading being high to 18.5%.
Abstract: Zn-Al layered double hydroxides (ZnAl-LDHs) were prepared on γ-Al2O3 by an in-situ synthesis method; with ZnAl-LDHs as the supports, a series of rare-earth element M (M=Y, La, Ce, Sm and Gd) doped M/Cu/ZnAl catalysts were then obtained through sequential wet impregnation method and used in the methanol steam reforming to produce hydrogen. The M/Cu/ZnAl catalysts were characterized by XRD, SEM-EDS, N2 sorption, H2-TPR, XPS and N2O titration and the effect of rare-earth metal doping on their catalytic performance in the methanol steam reforming was then investigated. The results showed that the activity of Cu/ZnAl catalyst is closely related to the copper surface area and the reducibility; larger copper surface area and lower reduction temperature lead to a higher catalytic activity in methanol steam reforming. The addition of rare-earth elements including Ce, Sm and Gd can improve the copper dispersion, surface copper area and the catalyst reducibility, which is helpful to enhance the activity of M/Cu/ZnAl catalysts. Especially, the Ce/Cu/ZnAl catalyst exhibits the highest activity; over it, the methanol conversion is 100% (about 40% higher than that over the Cu/ZnAl catalyst) and the CO concentration in the product is only 0.39%, for the methanol steam reforming at 250℃.
Abstract: The reaction pathways for the oxidation of C6H2(OH)3CH3 oxidizing into hydroxyl benzoic acid were investigated by using density functional theory (DFT) method at the GGA/BP levels with Materials Studio 8.0 program. The results illustrated that the reactions for the oxidation of hydrogen on the methyl into hydroxyl, the hydroxyl to aldehyde, and then the aldehyde to carboxylic are all exothermic. As the main path, the oxidation of C6H2(OH)3CH3 to hydroxyl benzoic acid follows:C6H2(OH)3CH3+3O → C6H2(OH)3C(OH)3 → C6H2(OH)3COOH+H2O; as the controlling step, the conversion of hydroxyl to carboxyl exhibits a high energy barrier (130 kJ/mol) and a low reaction rate (ln(k)=-22.96 s-1). The oxidation of hydroxyl and aldehyde to carboxylic acid follows the sequence of -CHO > -C(OH)3 > -HC(OH)2 > -H2C(OH). An increase in the temperature and oxygen concentration is beneficial to the formation of hydroxyl benzoic acid, whereas appropriate catalyst can promote the whole reaction process.
Abstract: The γ-Al2O3 modified with different content of SiO2 by impregnation method was used as supports to prepare Co/Al2O3 catalyst.The effects of SiO2 additives on phase structure of the cobalt-based catalysts, reduction behavior and the influence on the F-T synthesis performance were studied by using N2 adsorption, XRD, H2-TPR and XPS characterization methods and activity test.The results showed that with the introduction of SiO2, the interaction between support and cobalt was effectively weakened, thus the reducibility and catalytic activity of the catalysts were significantly improved.However, when the amount of SiO2 continued to increase, the reduction degree of the catalyst continued to improve, but the dispersion decreased by 32% at the same time.Compared with unmodified Co/Al2O3 catalyst, the activity of the catalyst remained basically unchanged.
Abstract: In order to gain an insight into the relationship between pretreatment condition and catalyst attrition resistance, an iron-based model catalyst for Fisher-Tropsch synthesis was carburized at 300℃ for different times and extensively characterized by multiple techniques; the effect of carburization and carbon deposition on the catalyst attrition resistance was then investigated.The results indicated that at the initial stage of pretreatment, the carbide content increases with the increase of carburization time, whereas the BET surface area and particle size are decreased, leading to an increase in the catalyst attrition resistance.With further increasing the carburization time above 72 h, the carbide content keeps almost constant, whereas the carbon deposition content, particle size and catalyst weight are increased, accompanying with a decrease in the attrition resistance.
Abstract: Pt/SAPO-11 bifunctional catalyst was modified with citric acid and carbon black.The effects of different modified methods on the catalytic activity of Pt/SAPO-11 catalysts were investigated using n-tetradecane as the probe reaction.Results indicated that the isomerization products were mainly composed of monomethyl isomer, the modification has not changed the acid strength of the catalyst, but the acid concentration has decreased.The citric acid significantly improved the low temperature catalytic activity of the catalysts, while carbon black effectively promoted the mass transfer performance and monomethyl isomer selectivity of the catalysts.The cracking products were mainly composed of C6 compounds, and modification did not change the shape selective effects of SAPO-11 molecular sieve.Carbon number distribution of cracking products was obvious asymmetric distribution.
Abstract: Co-Al layered double hydroxides were prepared by co-precipitation method and converted into composite oxides via calcination.The composite oxide were then used to prepare a series of Ru/Co-Al-O supported catalysts.The structures and properties of the catalysts were characterized by XRD, BET and FT-IR.The hydrodeoxygenation (HDO) properties of these catalysts were tested by using 4-methylphenol as a typical oxygen-containing model compound of lignin biomass oil.This study concentrated on the effects of Co/Al molar ratio and the reduction temperature of the catalyst on the hydrodeoxygenation activity of Ru/Co-Al-O and the optimization of HDO temperature.The results showed that when the molar ratio of Co/Al was 3:1, the catalyst reduction temperature was 350℃ and the reaction temperature was 275℃, the HDO activity was the highest:both the conversion and deoxygenation degree in the HDO of p-methyl phenol reached up to 100%.
Abstract: A series of Fe-Cu/ZSM-5 catalysts with different Fe/Cu molar ratios were prepared by impregnation method and characterized by XRD, H2-TPR, NH3-TPD and in situ DRIFTS; their performance in the denitrification (de-NOx) process via NH3-SCR was investigated.The results showed that the bimetallic modified Fe-Cu/ZSM-5 catalysts have a broad active temperature window.Especially, the Fe-Cu/ZSM-5 1:4 catalyst with a Fe/Cu molar ratio of 1:4 displays the highest activity; over it, the deNOx efficiency reaches the maximum of 99.46% at 335℃ and keeps above 90% at 250-450℃.Copper and iron species, present as amorphous oxides, are finely dispersed on the catalyst surface and the bimetallic modified catalysts retain the crystal structure of ZSM-5.The Fe-Cu/ZSM-5 1:4 catalyst exhibits abundant acid sites and excellent redox performance.E-R mechanism and L-H mechanism may coexist during the NH3-SCR reaction under certain temperature; moreover, the onset temperature of E-R mechanism is much lower than that of L-H mechanism and the denitration reaction may be ignited at 200℃.
Abstract: In the light of a high SO2 oxidation ratio of the recycled waste SCR catalyst during conventional recycling denitrification, a novel recycling technique, including acid washing, acid leaching under reduction condition and active components loading, was proposed to control the SO2 oxidation ratio of the recycled catalyst.The experiments were performed to determine the components, denitrification efficiency and SO2 oxidation ratio of the catalysts obtained in different recycling runs, and the catalysts used were characterized.The results indicate that the denitrification efficiency and SO2 oxidation ratio of the fresh catalyst, waste catalyst, conventional recycled catalyst and novel recycled catalyst are 99.0% and 0.43%, 77.0% and 0.46%, 94.2% and 0.80%, 99.3% and 0.48%, respectively.Through novel recycling method, both denitrification efficiency and SO2 oxidation ratio of the recycled catalyst are well recovered.The characterization results suggest that the highly polymerized vanadium species on the surface of the waste catalyst could not be removed by using conventional recycling method, but the novel recycling method is effective for removing these vanadium species and replacing them with highly dispersed vanadium species, resulting in a reduction of SO2 oxidation ratio of the recycled catalyst.
Abstract: The mesoporous materials MCM-41 and Co-MCM-41, with Co/Si(molar ratio)=0.18, were prepared by hydrothermal synthesis method with cobalt nitrate as cobalt source and characterized by X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR) and nitrogen adsorption-desorption.XRD and FT-IR results indicated that Co was introduced into the framework of mesoporous materials.The MCM-41 and Co-MCM-41 with highly ordered hexagonal mesoporous structure had been synthesized when the Co/Si(molar ratio) was 0.18 or less.But the sample had lost its ordered hexagonal mesoporous structure when Co/Si(molar ratio) was 0.22, indicating that the maximum addition amount of Co was about Co/Si(molar ratio)=0.18 when Co-MCM-41 was synthesized by using cobalt nitrate as cobalt source.Compared with the MCM-41, the intensity of XRD peak (100) of Co-MCM-41 became weak, broad and its surface area and total pore volume decreased, but the average pore diameter increased with the increase of Co amount.However, there was small amount of highly dispersed Co3O4 on the channel surface of Co-MCM-41 samples when the Co/Si(molar ratio) was 0.06 or more.Denitrification of model fuels containing about 1737.35 μg(nitrogen)/g of quinoline, aniline or pyridine was studied over the synthesized Co-MCM-41 with static adsorption at ambient conditions.The sequence of adsorption denitrification performance over all Co-MCM-41 samples was aniline, pyridine and quinoline.The adsorption capacity of Co-MCM-41(0.06) for aniline, pyridine and quinoline was 42.17, 35.66 and 29.18 mg(N)/g and the removal rate of basic nitrogen was 82.38%, 73.53% and 61.11% respectively.The coexisting aromatic compounds in model fuel had little impact on the removal performance of basic nitrogen over Co-MCM-41(0.06), implying that the N-M bond between the adsorption sites and N atom in the compound plays a significant role.Furthermore, Co-MCM-41 could be easily regenerated its adsorption denitrification performance by using calcination or ethanol regeneration method.
Abstract: A series of Ru-Ni/Al2O3 catalysts were prepared via adsorption-precipitation method, using Al2O3 as the support and RuCl3·xH2O and Ni(NO3)2·6H2O as precursors.Effects of pretreatment conditions and the amount of Ni on the catalytic behaviors of the catalysts were investigated.The catalytic activities of Ni-modified Ru catalysts increased with the increase of the Ni content firstly and then decreased.The highest hydrogenation activity was obtained as the atomic ratio of Ni:Ru is 6:1.The catalytic activity of Ru1Ni6/Al-fresh subjected to reduction at 200℃ has no significant difference with the sample reduced at 400℃, reaching to 1.5 times that of Ru/Al2O3 with the same pretreatment.Based on the results of XPS, XRD and H2-TPR, the reason for the promoted catalytic effect of Ni was disclosed.It was found that the dispersion of Ru could be improved as the promotion of Ni, resulting in the improvement of the catalytic performance of the Ru catalyst.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
