Abstract: Jinjitan coal and sand were respectively chosen as raw material and additive. Under the different proportion of additive, ash fusion and viscosity behavior of coal ash with high contents of Fe and Ca were studied. X-ray diffraction (XRD), high-temperature stage microscope (HTSM) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) were applied to investigate effect of mineral transformation on ash fusion and viscosity behavior of coal ash. The results show that ash fusion temperature decreases at first and then increases with the rising content of additive, and formation of low temperature eutectic augite is the main reason for the lower ash fusion temperature. The viscosity fluctuation is related to the formation of gehlenite, and the precipitation of iron-bearing minerals causes significant increase of viscosity. The temperature of critical viscosity (tcv) of coal ash slag drops dramatically and the slag type transforms from crystal slag to glass slag with addition of sand. Distribution of Fe and Ca shows obvious different in raw coal slag, but additive makes it become more uniform, which is in agreement with the viscosity curve. Moreover, the industrial results prove that sand is an effective additive to improve the viscosity behavior of coal ash with high content of Fe and Ca.
Abstract: The structural parameters including La, Lc and d002 of 28 coal samples with the maximum vitrinite reflectance Ro, max varying from 0.30% to 2.05% were analyzed using X-ray diffraction (XRD). The change in the XRD parameters associated with increasing vitrinite reflectance was obtained. The results indicate that, for the test coals with Ro, max less than 1.0%, the values of La and Lc sharply increase while d002 shows a reverse trend, and the decrease of oxygen-containing functional group and the length of branching aliphatic side chains are dominated. For those with Ro, max from 1.0% to 1.6%, the value of La continuously increases, d002 increases first and then decreases, and Lc decreases first and then remains steady. Moreover, dehydrogenation and adjusting the space steric hindrance are simultaneous. The value of d002 continues to decrease while La and Lc increases, and the variation of coal structure is dominated by aromatization process during the Ro, max range of 1.6% to 2.0%. The variation of XRD parameters presents close relation with the first and the second coalification jump phase.
Abstract: An integrated experimental apparatus for pyrolysis/co-pyrolysis was employed to carry out the upgrading process of sawdust, Yunnan lignite, and their blends. The slurry-ability of the upgraded char was investigated. The results show that the slurry-ability of sawdust and Yunnan lignite is significantly improved via pyrolysis process. Bio-char and semi-coke were prepared at 500 ℃ holding 1.5 h. The solid loadings of the resulting slurry fuels derived from sawdust and lignite were enhanced from 29.21% and 54.63% to 38.57% and 60.19%, respectively. Under the same pyrolysis conditions, the slurry-ability of the char prepared from co-pyrolysis of sawdust and Yunnan lignite is apparently superior to that of the corresponding bio-char/coal char mixture with the same original mass ratio of feedstock. The prepared char-water slurries generally display pseudo-plastic behavior, i.e., the shear press decreases with increasing shear rate. When the mass ratio of sawdust exceeds 50%, the rheological property of char-water slurry tend to be shear thickening, exhibiting strong dilatant behavior at low shear rate, which is similar to the rheological property of biochar-water slurry. The desirable slurry-ability of the char produced from co-pyrolysis could be attributed to the synergistic effect of biomass and coal, which is likely to improve aromaticity of the resulting hybrid char.
Abstract: Adopting tetrahydrofuran solubles of coal tar pitch (THFS) for petroleum asphalt modification, effects of different amounts of mixing, blending temperatures and cross-linking agent on the modified asphalt performance were examined. The optimum blending conditions were determined as amount of THFS, formaldehyde and trioxymethylene cross-linking agents being 8%, 0.8% and 0.2%, respectively at 135 ℃. Hexane soluble (HS) leads to the penetration and ductility of modified asphalt increase, but asphaltene (A) and preasphaltene (PA) improve the temperature sensitivity and raise the softening point. The addition of cross-linking agent improves the aging performance of modified asphalt; the methyl (CH3) and methylene (CH2) transmission peak intensity of modified asphalt gradually become stronger; the substituted benzene ring transmission peak intensity at 770-730 cm-1, 710-690 cm-1 and 770-810 cm-1 gradually increases, and C-O-C vibration transmission peak intensity of 1 010-1 270 cm-1 increases. The pyrolysis peak temperature moved to higher temperature, and the increase of char yield is about 2%. The modified particles exhibit a continuous distribution of flow lines, the streamline distribution of modified asphalt with adding trioxymethylene is more concentrated.
Abstract: The direct conversion of syngas to lower olefins is one of the most challenging subjects in the field of C1 chemistry; it is considered as a new attractive route for producing lower olefins from non-petroleum resources, owing to its process simplicity and low energy consumption. Bifunctional catalysis using composite catalysts such as OX-ZEO and Fischer-Tropsch to olefins (FTO) reaction are two main pathways for the direct conversion of syngas to lower olefins. In this paper, the recent research progress made in the direct conversion of syngas to lower olefins via these ways was reviewed. The catalysis mechanism for olefins formation, the design and development of novel catalysts, as well as the effect of various additives on the catalyst performance were considered; lastly, an expectation outlook was given on the future trend for the direct conversion of syngas to lower olefins.
Abstract: Bimetallic Co/Fe catalysts supported on carbon nanotubes (CNTs) were prepared, and niobium (Nb) was added as promoter to the 70Co:30Fe/CNT catalyst. The physicochemical properties of the catalysts were characterized, and the catalytic performances were analyzed at the same operation conditions (H2:CO (volume ratio)=2:1, p=1 MPa, and t=260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane, and the selectivity to C5+ increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C5+. Meanwhile, a decrease in methane selectivity is observed.
Abstract: The Fischer-Tropsch synthesis has offered an alternative way to convert coal and biomass into chemicals such as α-olefins via sygas comprised of H2 and CO. A pulse process switching between Fischer-Tropsch synthesis and N2 purging was carried out when the Fischer-Tropsch synthesis became stable in the fixed bed reactor. The activity and selectivity over Fe-Co catalyst for α-olefins in Fischer-Tropsch synthesis reaction were measured under the normal conditions of 2.0 MPa, 497 K, 2 000 h-1 and H2/CO volume ratio of 2.0. It was found that the olefin to paraffin ratio of C3 for Fe-Co catalyst purged at 517 K and 0.2 MPa was almost nine times higher than that of the fresh one without purging under the same reaction conditions, and the CH4 selectivity and CO conversion decreased after purging. Two possible reasons were proposed to explain these phenomena. Moreover, a batch experiment by the pulse process in fixed bed reactor was performed. Notably, a high olefins yield was obtained via the pulse process during the Fischer-Tropsch synthesis.
Abstract: AlOOH were prepared by precipitation-hydrothermal method with different water-to-gel ratios, which were mixed with industrial methanol synthesis catalyst C302 and tested for CO hydrogenation in the fixed-bed reactor. The AlOOH samples were characterized by XRD, FT-IR, BET, NH3-TPD-MS, TG-DTG and H2-TPR. The results showed that the ratios of water-to-gel in the hydrothermal process had obvious influence on the preferred orientation, pore structure and surface acidity of AlOOH, leading to the different selectivity of higher alcohols and DME. When the ratio of water-to-gel was 2:1, AlOOH showed in (020) and (120) preferred orientation. Moreover, it had larger pore volume and proper ratio of weak acid sites to strong acid sites, the composite catalyst showed a relatively high selectivity of higher alcohols, which indicated that AlOOH favored the growth of carbon chains. This study provided a new way for synthesis of higher alcohols from syngas.
Abstract: A series of ZrO2 nanoparticles with different particle sizes and different crystalline phases were prepared using coprecipitation and hydrothermal methods. Their physico-chemical properties were characterized by N2 physisorption, XRD, TEM, Raman spectroscopy, XPS, and NH3-TPD techniques. The catalytic performances for syngas conversion were tested at 400 ℃, 3 MPa, gas hourly space velocity (GHSV) of 500 mL/(gcat·h), and H2/CO/Ar (volume ratio)=5:5:1. It was found that syngas can be directly converted into hydrocarbons over ZrO2 nanoparticles. The hydrocarbon products are mainly composed of isomerized olefins, cyclenes, and aromatics. The selectivity of C5+ hydrocarbons is up to 48%. Moreover, the aromatic concentration in C5+ ranges from 30% to 53% depending on ZrO2 structures. It is also found that the monoclinic ZrO2 shows higher activity than the tetragonal one. Monoclinic ZrO2 with larger specific surface area and acid amount show highest CO conversion as well as the yield of target products, but the monoclinic ZrO2 with lager particle size has the higher acid surface density and results in the higher aromatic selectivity. Consequently, acidity is the key factor for CO conversion. And high acid surface density promotes the formation of aromatics but acid amount affects the activity.
Abstract: Glucose and cellobiose were used as model compounds to investigate the effect of retro-aldol condensation and hydrogenation rates on the product distribution of cellulose conversion. It was shown that the product distribution obtained over the physical mixture of Ni/SBA-15 and WO3/SBA-15 in the glucose and cellobiose conversions were different from that attained on the Ni-WO3/SBA-15 prepared by the co-impregnation method. The ethylene glycol (EG) yield depended on the structures of tungstic compounds, and it increased in the order of WO3 < WO3/SBA-15 < (NH4)6W7O24·6H2O (AMT), while the particle sizes of them decreased in such an order. Regardless of the types of tungstic compounds, the EG yield obtained in the glucose conversion is lower than that attained in the cellobiose conversion at the same amount of catalyst.
Abstract: The catalytic activity of CoMoS/CNT towards the Egyptian heavy vacuum gas oil hydrotreating was studied. The delivered CNT was functionalized with 6 mol/L HNO3. The CNT were loaded with 12% MoO3 (by weight) and 0.7 Co/Mo atomic ratio with impregnation methods. The γ-Al2O3catalyst was also prepared by impregnation method to compare both catalysts activities. The analysis tools such XRD, Raman spectroscopy, TEM, and BET were used to characterize the catalysts. The autoclave reactor was used to operate the hydrotreating experiments. The hydrotreating reactions were tested at various operating conditions of temperature 325-375 ℃, pressure 2-6 MPa, time 2-6 h, and catalyst/oil ratio (by weight) of 1:75, 1:33 and 1:10. The results revealed that the CoMoS/CNT was highly efficient for the hydrotreating more than the CoMoS/γ-Al2O3. Also, the hydrodesulfurization (HDS) increased with increasing catalyst/oil ratio. Additionally, results showed that the optimum condition was temperature 350 ℃, pressure 4 MPa, catalyst/oil ratio of 1:75 for 2 h. Furthermore, even at low CoMoS/CNT catalyst/oil ratio of 1:75, an acceptable HDS of 77.1% was achieved.
Abstract: Effects of temperature, pressure, acetic acid (HAC) feeding rate and H2/HAC (GHSV or H2 flow) on the conversion of acetic acid, product selectivities and the productivity of ethanol in selective hydrogenation of acetic acid to ethanol were investigated in a fixed-bed reactor. The good stability of the lab-made catalyst was verified. The results show that the reaction rate of esterification and decarboxylation/ketonization are very fast. Selectivities of ethyl acetate and acetone are affected by the catalyst composition and reaction conditions. The hydrodecarbonylation of acetic acid to methane and the further conversion of ethanol can be avoided when the contact time of the reactants with the catalyst is less than 5 s. Optimum reaction conditions were found at 280 ℃, 2.5 MPa, LHSV=0.72 h-1, H2/HAC (mol ratio)=16, under which the selectivity of ethyl acetate could reach 6%.Life time test more than 900 h shows that the lab-made catalyst has a good potential for industrial application.
Abstract: CuO/CeZrO2 catalysts doped with different amounts of Dy2O3 and Y2O3 were prepared by the hydrothermal-impregnation method and characterized by XRD, H2-TPR and nitrogen sorption; the effect of Dy and Y doping on the catalytic performance of CuO/CeZrO2 for the preferential oxidation of CO in H2-rich stream was investigated. The results indicate that all the CuO/CeZrO2 catalysts have a fluorite structure; doping with appropriate amounts of Dy2O3 and Y2O3 can improve the interaction between the active component and support, the dispersion of CuO and its reducibility at low temperature, which is effective to enhance the activity of Dy and Y doped CuO/CeZrO2 catalysts in the preferential oxidation of CO. Moreover, the doping with Dy2O3 and Y2O3 can also reduce the inhibition effect of CO2 on CuO/CeZrO2 in CO oxidation and then improve its catalytic stability.
Abstract: A novel PW-coupled polyionic liquid (1-n-butyl-3-vinylimidazolium phosphotungstate) (PBVImPW) was successfully synthesized and characterized by FT-IR, XRD, TG, ICP and CHN analysis. The prepared catalyst was applied in oxidative desulfurization processes of the model oil in the presence of H2O2. Several parameters including temperature, time, the amount of hydrogen peroxide and catalyst were investigated. PBVImPW is proved to be a highly efficient catalyst, and 99.4% benzothiophene conversion is achieved at reaction temperature of 50 ℃, n(H2O2)/n(S) ratio of 8, n(PBVImPW (P))/n(BT) ratio of 0.4 and reaction time of 150 min. There is not a significant decrease in the activity of the catalyst after being recycled four times.
Abstract: Pt/β-zeolite catalysts were modified with Ce, Cr, Mo and Cu by impregnation method and characterized by nitrogen sorption, XRD, H2-TPR, NH3-TPD and XPS; the effects of metal modification on the textural properties, skeletal structure, surface acidity as well as the catalytic performance in the oxidation of SO2, HC and CO in the simulated diesel exhaust gas were investigated. The results indicate that metal modification has little influence on the textural properties and skeletal structure of the Pt/β-zeolite catalyst, whereas the addition of Cu, Cr and Mo can change the acid strength and has a stronger inhibition effect on the oxidation of SO2. Especially, the Cu-modified Pt/β-zeolite catalyst exhibits the best ability to inhibit the oxidation of SO2; the SO2 conversions over Cu modified catalyst under 350 and 450 ℃ are decreased by 70.4% and 70.2%, respectively, in comparison with those over the unmodified Pt/β-zeolite catalyst. However, because of the interaction between metal and Pt species, Pt species becomes more difficult to reduce over the metal modified Pt/β-zeolite catalysts, which may lead to a decrease of their catalytic activity in the oxidation of HC and CO.
Abstract: Based on commercial V2O5-WO3/TiO2 catalyst, two methods to simulate CaSO4 poisoning were designed, and the physico-chemical properties of fresh and poisoned catalysts were investigated by BET specific surface area measurement, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), scanning electron microscope (SEM) and in-situ diffuse reflectance infrared spectrometry (in situ DRIFTS). Meanwhile, the catalytic performance for selective catalytic reduction of NO with NH3(NH3-SCR) in a fixed bed was also explored comparatively. SEM results show that CaSO4 plugs the small hole (pore width smaller than 2.7 nm) and big hole (pore width bigger than 17.8 nm), causing the loss of surface area and pore volume. CaSO4 could weaken the intensity of both Br∅nsted acid Sites and Lewis acid sites, particularly the active centers of Br∅nsted acid sites, which hinders the absorption of NH3 and reduces the redox abilities.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
