Abstract: Modification performance of Hypercoal (HPC) extracted from brown coal as an additive on the structure of carbonization products through co-carbonization with two different coals was examined. The dimension and texture changes of products were observed using polarization microscope and scanning electron microscope. The results show that the pore structure of carbonization products from caking coal is improved by adding additive with larger size, however smaller particles and more additive amount are favorable for weakly caking coal. As a good candidate of binding substance with high thermoplasticity, HPC particles were found to have a tendency to be well dispersed and further excellent adhesion between coal particles. Excessive expansion of product from caking coal can be inhibited in appropriate conditions. The number and diameter of pore are reduced and pore walls are thickened by adding HPC. Fluidity and fusibility of weakly caking coal are accelerated by the colloid in additive, which would lead to mechanical properties of products improved. Moreover, more factors affecting the product structure via single-carbonization and co-carbonization were taken into account, including moisture in coal and molding pressure of artifact. Special pore structure is formed in the products owing to moisture, and the influence of molding pressure on products is different with coal properties.
Abstract: The effects of KOH loading on the hydrogasification of Hohhot(HH) coal and Pingzhuang(PZ) coal from Inner Mongolia were studied in a pressurized fixed-bed reactor, and the analysis methods of slag washing, atomic absorption and XRD were adopted to investigate the intrinsic characteristics of coal structure that affect the hydrogasification reactivity. The experimental results show that the total gas productivity of HH coal hydrogasification can be enhanced obviously by increasing the catalyst loading, and the catalyst loading saturation level is about 15%. On the other hand, KOH shows an inconspicuous effect on PZ coal hydrogasification unless the catalyst loading is higher than 30%, and the total gas productivity does not exceed 64% within 60 min reaction time when the catalyst loading is 50%. The XRD results indicate that as the hydrogasification proceeds, the catalyst is deactivated by reacting with the ash in coal, and the unreacted carbon in PZ coal is gradually transformed into less active graphite, resulting in a lower gasification rate at later reaction time. The ratio of water-soluble potassium to water-insoluble but acid-soluble potassium in the hydrogasification residue is closely related to the catalytic activity. When the catalyst loading is less than 20%, the high content ash in PZ coal will deactivate most of the loaded KOH, leading to a slow hydrogasification rate.
Abstract: Two coals (Ninglu and Xiaotun) with low and close ash fusion temperature were selected and blended with Tianchi coal having a high fusion temperature. The results show that the ash fusion temperature of the blended coal with Xiaotun increases more significantly with increasing ratio of Tianchi coal; and that with Ninglu coal varies little. Mineral transformation processes of blended coal-ashes were examined by XRD. The combustion residue of Ninglu coal contains lots of minerals such as hematite and anhydrite which have negative effects on the formation of mullite. The ash fusion temperature could not increase dramatically for the lack of mullite with high fusion temperature and playing a key supporting role in coal-ash melting. Some experiments of blended coals were carried out in a drop tube furnace to simulate slagging process in power plant boilers. SEM was applied to analyze the surface morphology of different residues. It is proved that Xiaotun coal blended with Tianchi coal could remarkably improve slagging characters.
Abstract: Ten Huainan coal ash samples with different ash fusion temperatures were selected. To calculate the flow temperature by using the typical empirical formulas based on ash chemical composition and the new approaching were conducted. The composition of crystal mineral in ashes was analyzed by using XRD combined with "Value K" method, and the relationship between crystal mineral composition and the flow temperature was determined. An available formula for predicting the coal ash flow temperatures based on the crystal mineral composition was proposed. It is found that the typical empirical formula has a big error for predicting, but the difference between experimental value and calculated value by proposed formula is less than 80℃ required by China National Standards.
Abstract: Reduction of NO and N2O with the simulated pyrolysis gas has been experimentally studied in an ideal plug flow reactor. The influences of reaction temperature, excess air number λ, concentrations of CH4, CO, H2, NH3 in the simulated pyrolysis gas, concentrations of NO and N2O in the flue gas on concentration of NO as well N2O and total nitrogen conversion efficiency have been discussed. The results show that CH4, CO and H2 cannot effectively react with NO at 973~1 223 K. About 0~30% of the inlet N2O can be reduced by CH4, CO, or H2 when λ is equal to or less than 1.0. Furthermore, about 10%~60% of the inlet NO can be reduced by NH3, however, no N2O concentration change is found when N2O is mixed with NH3 at 973~1 223 K.
Abstract: For the reason of the unstable evaporation in the tar sampling process and the difficulty of measuring and controlling reaction temperature, a moving bed as the tar sample introduction system was designed. A sample tray carrying tar was moved into the furnace with linear temperature distribution of the entrance zone. The movement of the tray instead of that of the tar, makes the tar sample introduction process more stable and the temperature easer to control. On this basis, tar cracking process and kinetic characteristics with the different sample introduction rate were studied. The results indicate the tar cracking rate is accelerated with increasing temperature at 573~1 123 K. The tar cracking rate reaches 58% at 1 123 K. The tar thermal cracking reaction is a first order reaction. On average, the activation energy is 39.5 kJ/mol and the pre-exponential factor is 1.58 min-1.
Abstract: A series of Ni catalysts supported on HY, SiO2, γ-Al2O3 and SAPO-11 were prepared by incipient-wetness impregnation and characterized by XRD, NH3-TPD, H2-TPR, BET and SEM techniques. Their catalytic performance in hydrodeoxygenation (HDO) of vegetable oil to produce the second-generation biodiesel was evaluated in a semi-batch reactor by using methyl palmitate as a model compound. Owning to the weak and medium acidic properties of SAPO-11, the Ni/SAPO-11 catalyst exhibits high activity in the HDO of methyl palmitate and capability of inhibiting the feedstock and long-chain alkanes from being cracked. The effect of Ni loading, reaction temperature and pressure on the HDO behavior over Ni/SAPO-11 catalyst was considered. Under 220℃ and 2 MPa, Ni/SAPO-11 catalyst with a Ni loading of 7% performs best in HDO; the conversion of methyl palmitate and the selectivity towards C9~16 alkanes reach 99.8% and 92.71%, respectively.
Abstract: The gasification reactivity of heavy oil residue chars in steam atmosphere was studied by Thermal Gravimetric Analyzer (TGA) and micro-crystalite of the char was analyzed by X-ray diffraction (XRD). The effects of heating rate, pyrolysis temperature, residence time, gasification temperature and the partial pressure of steam were evaluated separately. The results show that at 950℃ and 60% partial steam pressure, gasification reactivity of chars formed at slow heating rate is lower than that formed at fast heating rate. With increasing pyrolysis temperature and residence time, the reactivity of char decreases. Gasification temperature is the main factor influencing the gasification rate. From 900 to 1 050℃ the gasification time is almost halved with the increasing temperature of 50℃. The increasing of steam partial pressure can improve the gasification rates greatly until the partial pressure comes to 60%, and after that it has no significant effect. The homogeneous model and the shrinking core model were used to characterize the gasification kinetic parameters. The later model is better and the apparent activation energy is 195.0 kJ/mol, the preexponentiol factor A0 is 2.6×107min-1.
Abstract: The asphaltenes contain a lot of hetero-atoms, such as sulfur, nitrogen and oxygen, which play an important role on the polarity and association characteristics of asphaltenes. The n-heptane asphaltene was derived from the Tahe atmospheric residue (THAR). In addition, THAR n-heptane asphaltene was divided into three sub-fractions by difference of the polarities. The mean dipole moments of asphaltene sub-fractions were investigated. All of these asphaltene sub-fractions were measured by 1H-NMR spectrometry. From the spectra, the average structural parameters could be obtained in order to analyze the association characteristics. The structures of sulfur functional groups were analyzed by X-ray absorption near edge structure (XANES) to study the influence of sulfur atoms upon the characterization of asphaltene. The results showed that as the polarity increased, the ratio of H/C atom decreased and association increased. For all sub-fractions samples, thiophene was the most dominant functional group of the reduced sulfur and followed by sulfide. The oxidized form of sulfur was present predominantly as sulphoxide, sulfone and sulfonate. Thiophene, sulfone and sulfonate influenced the characteristics of asphaltenes, but did not determine the polarity and association of asphaltenes. Thus, the sulphur atoms were not the decisive factors to determine the polarity and association of asphaltenes.
Abstract: A comparative study on microstructure of asphaltenes obtained from an atmospheric residue (AR), a hydroprocessed oil of AR and a blending of AR with high aromatic light cycle oil (LCO) was carried out by element analysis, scanning and transmission electron microscopy (SEM and TEM). Different asphaltene morphologies, smooth surface and porous surface with spherical particles, were observed by SEM before and after hydroprocessing. The results of TEM micrographs show that the aromatic ring stacking of original asphaltene is characterized of long range disorder and short range order, and multi-stacking graphite-like carbon with long range order is observed for hydroprocessed asphaltene. The addition of high aromatic LCO into AR enhances the hydrogenation reactions of asphaltene and inhibits the aggregation of aromatic ring systems under AR hydrotreating.
Abstract: Two types of macroporous catalysts were prepared by using polystyrene particles (PS) and de-oiled vacuum residue (VR) as templates; their pore structure and catalytic performance in the catalytic cracking of heavy oil (FCC) were investigated. Compared with the traditional catalyst without using template, two catalysts using the PS and VR templates exhibit an increase of BET surface area by 38.0% and 46.2%, an increase of pore volume by 20.6% and 35.8%, and an increase of average pore size by 54.5 % and 27.3 %, respectively. Meanwhile, the conversions of heavy oil over two catalysts using the PS and VR templates are also increased by 9.8% and 12.2%, and the total liquid yields are increased by 10.2% and 7.3%, respectively, compared with that over the traditional catalyst. After enduring coke deposition in FCC, the activity of the macroporous catalysts was decreased as was expected, but still higher than that of the traditional catalyst at similar situation. The macroporous catalysts own a reasonable pore distribution due to the pore expansion with templates, which promotes the mass transfer in the macropores of the catalysts and provide them with higher tolerance towards coke deposition; these may contribute to their excellent performance in the catalytic cracking of heavy oil.
Abstract: A series of supported Cu-Fe catalysts with different oxides (ZnO, ZrO2, TiO2, SiO2, MgO, Al2O3) as support were prepared by co-impregnation method, and were characterized by XRD, N2-adsorption, H2-TPR and CO-TPD. Their catalytic performances for the synthesis of higher alcohols through CO hydrogenation were investigated in a continuous flow fixed bed micro-reactor at 250℃ under 3 MPa with the space velocity of 6 000 mL/(g·h). The results indicated that SiO2 supported Cu-Fe catalyst (Cu-Fe/SiO2) possessed high CuO dispersion which could be easily reduced at low temperatures, and had strong capability for CO adsorption, therefore, exhibited both higher CO conversion and higher selectivity to higher alcohols.
Abstract: Effects of CO and H2 pretreatment on the Fe2O3 catalyst and its catalytic performance on the light olefin production through CO hydrogenation were investigated. It was indicated that the catalyst sample pretreated with H2 at 300℃ favored the formation of Fe3O4 and α-Fe phases. Fe3O4 was formed with CO pretreatment at 250℃. And, with the increase of pretreatment temperature, iron carbides were formed. The TPD experiment showed that the surface basicity of the catalyst pretreated with CO was stronger than that with H2. Surface carbonaceous deposition caused decrease of CO2 and CO adsorption. Comparing to H2 pretreated catalyst, CO pretreated catalyst has higher selectivity to light olefins.
Abstract: Cox-MoS3-Ky/γ-Al2O3 catalyst was prepared by microwave-assisted impregnation and used for higher alcohols synthesis from CO hydrogenation; the effect of K or Co content on its catalytic performance was investigated. The results showed that appropriate amounts of K and Co can promote the formation of K-Mo-S and Co-Mo-S phases, which enhances the catalytic activity of CO hydrogenation and prevents active components from agglomeration and blocking the support pores. The optimal mol ratios of K/Mo and Co/Mo that are beneficial for the formation of higher alcohols are 1.0 and 0.2, respectively.
Abstract: By using rectorite as raw materials, the Al-pillared rectorite(Al-PILR) was synthetized, then the Cu/Dy/S2O82-/Al-PILR catalyst was prepared by loading of (NH4)2S2O8, Dy(NO3)3 and Cu(NO3)2 onto the Al-pillared rectorite step by step. The catalytic performance of the Cu/Dy/S2O82-/Al-PILR catalyst on the selective catalytic reduction of NO with propylene was investigated. The relationship between the structure and the performance of the Cu/Dy/S2O82-/Al-PILR catalyst was also explored by means of Low-angle X-ray diffraction (LAXRD), Surface area measurements (BET), Pyridine absorption infared spectrum (Py-IR), Infrared spectroscopy (IR), Thermal gravimetric analysis (TG) and Scanning electron microscope (SEM). The experimental results indicated that the Al pillaring agent could effectively insert into the layer of rectorite and remarkably enlarge the specific surface area, and S2O82- could obviously increase the Brönsted acid amount of the Al-pillared rectorite, Dy could further increase the Brönsted acid amount to improve the catalytic activity and thermal stability effectively. Therefore, the Cu/Dy/S2O82-/Al-PILR catalyst exhibited excellent catalytic performance. The NO conversion was up to 80.3% at 300℃ and 77. 6% even at the presence of 10% volume fraction of water vapor.
Abstract: A Ni-Pt bimetal catalyst (Ni-Pt/γ-Al2O3) supported on self-synthesized γ-Al2O3 nano-film with a surface area of 349 m2/g was prepared via conventional impregnation method. The catalyst was characterized by BET, XRD, SEM and TEM and its performance in methylcyclohexane (MCH) dehydrogenation was evaluated in a fixed-bed microreactor connecting with a gas chromatograph. The results showed that under 350℃ and a volume gas space velocity of 252 h-1, the conversion of MCH over the 20%Ni-0.5%Pt/γ-Al2O3 catalyst reaches 96.99% and the selectivity to toluene approaches 100%.
Abstract: Combustion experiments (3 coals, 3 coals with addition of 1%, 3%, 5% CaBr2 and Ca(CH3COO)2, and a coal with addition of Fe2O3) were conducted on a high temperature electric heating reactor at 1 250℃. The fly ashes were collected and the particulate Hg (Hgp) contents were analyzed. The specific surface area, EDS, and XRD analysis were performed. It is indicated that the Hgp formations characteristics of the 3 coals were rather different. The ash of coal 3 has the largest specific surface area, but the lowest Hg content and Hgp ratio in its ash. CaBr2 addition leads to significant increment of Hg content in ash and Hgp ratio. Ca (H3COO)2 and Fe2O3 addition do not lead to prominent increase of Hgp.
Abstract: A series of supported perovskites La0.8Sr0.2MnO3/SBA-15 catalysts were prepared by step coating NH3/water vapor-induced internal hydrolysis method, and characterized by XRD, BET, TG-DTG, XPS and H2-TPR. Their catalytic performances for toluene combustion were evaluated on a continuous-flow fixed-bed reactor. The results showed that step coating NH3/water vapor-induced internal hydrolysis method is favorable for the entrance of La0.8Sr0.2MnO3 into pore structure of SBA-15, and the formation of perovskites phase. The formation of perovskites crystal and lattice oxygen can provide more active sites, promote the catalytic activity of toluene combustion.
Abstract: The pyrolysis behaviors of three kinds of typical plastics like polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) were investigated through thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The results showed that the thermal stability of these plastics increases following the sequence of PVC < PS < PE. PE pyrolysis is a typical one-stage reaction and involves irregular chain scission; the products of PE pyrolysis are complicated and changed gradually during the pyrolysis process: alkanes are the main products in the preliminary stage, while alkenes with trace amount of alkynes are the main products in the rest of pyrolysis process. PS pyrolysis is also a typical one-stage reaction with styrene as the main product, which suggests that the main reaction is depolymerization of PS to styrene monomer. PVC pyrolysis includes two events, i.e. dechloridation of PVC and rearrangement of conjugated polyene, in which aromatic compounds were found in the pyrolysis products; the dechloridation of PVC and the rearrangement and cyclization of conjugated polyene may take place simultaneously, which creates the potential for producing dioxin during PVC pyrolysis.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
