Abstract: The depolymerization behaviors of Xianfeng lignite (XL) in ionic liquid 1-butyl-3-methyl-imidazolium trifluoromethanesulfonate ([Bmim]OTf) were studied in this paper. Also, the thermal extracts and residues obtained from thermal depolymerization of XL at different extraction conditions were analyzed. It was found that [Bmim]OTf had good performance in the depolymerization of XL when the extraction was carried out at 280℃ for 4h with [Bmim]OTf/XL at 3.5. The extraction yield of XL with [Bmim]OTf defined as tetrahydrofuran solubles (THFS) reached to 20.1%. The depolymerization of XL with [Bmim]OTf was promoted markedly with the addition of tetralin (THN), H2 and ZnCl2 catalyst, and the yield of THFS reached to 30.0%, 36.9% and 46.8%, respectively. The results showed that the amount of hydrogen bonds in thermal extracts increased significantly with the addition of THN. The contents of aromatics and aliphatic hydrocarbon were enhanced greatly under the existence of H2 and ZnCl2.
Abstract: Vitrinite was separated and enriched from the 2nd long flame coal seam in Dongsheng coal mine by flotation and centrifugation. Structural parameters of groups were obtained from proximate and ultimate analysis, as well as 13C-NMR and FT-IR spectrum. The contents of carboxyl and carbonyl in the vitrain are from 8.91 to 10.90 mol/kg and from 1.61 to 1.79 mol/kg, respectively. Carboxyl is lost rapidly with increasing pyrolysis temperature. Methyl and methylene groups attached in the form of end groups to oxygen in the aliphatic chain or an aliphatic ring structure are removed first, and is basically stable above 350 ℃. The variation in occurrence of oxygen functional groups is the result of competition between aromatic and aliphatic system. Aromatic and aliphatic oxygen in coal pyrolyzed at 510 ℃ are 7.49 and 3.45 mol/kg. The evolution of hydroxyl is closely associated with the occurrence of oxygen. The content of various hydroxyls reduced along with the increasing temperature. Destructive effect on macromolecular network caused by pyrolysis interferes various hydrogen bonds, while the hydroxyl-π effect is enhance. The chemical activity order of oxygen in the coal is [COOH] > [R-O] > [Ar-O-Ar, Ar-O-C, C-O-C] > [C=O]. The contents of inactive and active ether in the vitrain are 0.68 and 0.48 mol/kg, respectively.
Abstract: Raman spectrum of coal tar was measured by using 355 nm laser at ambient temperature. Simultaneously, Raman spectra of 15 components which each weighted more than 1% in coal tar were also simulated. The calculated results are in good agreement with the experimental ones and the vibrations of Raman spectra of coal tar are assigned. The results indicate that the most components of coal tar are mainly composed of six-membered ring type hydrocarbons with the characteristic bands at 1 660, 1 420 and 1 265 cm-1, which are attributed to the C-C stretching vibrations. When the hydrocarbons connect each other in a resonant mode and chain-like structure, 1 420 cm-1 band is demonstrated significantly. When the hydrocarbons are embedded by the five-member ring type hydrocarbons, the intensity of 1 265 and 1 660 cm-1 band increases significantly. There is little effect on the spectra of the component molecule provided the five-membered ring type hydrocarbons, heteroatom groups and methyl are only connected at the edge of the component molecule.
Abstract: The fast hydropyrolysis of Huolinhe lignite were carried out under pressure in a tubular reactor with a transporter for coal samples. The effect of H2 on CH4 evolution and crack of chemical bonds were analyzed. Under pressure fast hydropyrolysis conditions, CH4 yield was higher under H2 atmosphere than that under N2 atmosphere, and increased with increasing temperature and pressure. Compared with N2 atmosphere, the yield of CH4 increased by 72.5% under 50% H2 atmosphere at 900 ℃ and 1.0 MPa. H2 or H· free radical induced the cracks of aromatic rings, side chains, ether linkages and aliphatic chains in the char, which could promote the coal pyrolysis. The increased yield of CH4 was mainly due to the external donor H. Below 700 ℃, the action of H2 with active groups in coal structure affected the pyrolysis of coal; above 700 ℃, hydrogenation of char promoted coal pyrolysis, leading to an increase in CH4 yield.
Abstract: To examine the effects of steam on the char reactivity and its microstructure, experiments of drying and pyrolysis of brown coal as well as the in-situ gasification of "hot" char were carried out in a newly-designed two-stage reactor. The reactivity and microstructure of in-situ gasification char were characterized by TGA, BET and Raman spectroscopy respectively. The results show that at low temperature of 600 ℃, the steam has little effect on the conversion, reactivity and microstructure of char. When it reaches 700~900 ℃, there are different change trends before and after 2 min of reaction between char and steam. In the first 2 min, the reactivity, the ratio of small aromatic ring systems (3~5 rings) to the large fused rings (≥6 rings) and O-containing functional groups decrease dramatically although the char conversion varies little; after 2 min, however, char conversion increases gradually, char reactivity, the ratio of small to big aromatic ring systems and O-containing functional groups decrease slowly. In addition, the pore structure of char follows almost the same variation before and after 2 min. During the first 2 min, a sharp decrease of the ratio of small to big aromatic ring systems and O-containing functional groups are the important factors leading to the decrease of char reactivity; while after 2 min, the change of aromatic ring systems results in the further decrease of char reactivity.
Abstract: Acid-washing brown coal samples loaded with different content of iron catalyst were pyrolyzed in a fixed bed reactor. The effect of iron on coal char functional group, carbon crystallite structure, surface active site and gasification reactivity were investigated by FT-IR, Raman spectra,TPD and TG. FT-IR results reveal that the numbers of -OH、-CH3、-CH2 active functional groups increase significantly during catalytic pyrolysis. Raman spectra results show that IG/Iall reduces from 0.095 to 0.087 and ID3/Iall increases from 0.090 to 0.097 with the increase of iron loading, respectively. It means that partial large polyaromatic ring structures transform into small polyaromatic ring structures under the catalytic action of iron. TPD experimental results indicate that the numbers of active sites increase with the increase of iron loading. With 3% Fe loading, the numbers of active sites rise with the increase of adsorption temperature until 800 ℃, and then start to decrease. The adsorption quantity of CO2 increases with time at 750 ℃, and reaches saturated adsorption state after 45 min. Coal char-steam isothermal gasification experiment result suggests that the gasification reactivity of coal char has a close relationship with the number of active sites, and the iron catalyst can enhance the char gasification reactivity by increase the number of surface active sites.
Abstract: The hydro-liquefaction properties of Xiaolongtan (XLT) lignite were investigated, and structures of the heavy products, including asphaltene (AS) and preasphaltene (PA) were characterized by elemental analysis, FT-IR and fluorescence spectroscopy. The results indicate that XLT lignite shows high liquefaction reactivity, and its conversion catalyzed by FeS at 415 ℃ is 89.6%. During hydro-liquefaction, the macro-molecule of coal are pyrolyzed and deoxygenized. The aromatic structure units in AS and PA are similar to those in the coal. Hydroxyl and carbonyl in the form of aromatic ketone are main oxygen containing groups in AS and PA. The relative content of aromatic structure of PA, dominant in the archipelago molecular architecture, is obviously higher than that of AS. In THF solvent, PA shows significantly stronger aggregation than AS, especially an intra-molecular aggregation observed in a dilute solution. The AS and PA produced at high liquefaction temperature contain more aromatic structure, and show stronger aggregation.
Abstract: Zn and P were selected to modified HZSM-5 molecular sieve for further improving the production and fuel quality of refined bio-oil. Analysis methods including XRD, SEM EDS, ICP-AES and BET were applied to characterize the modified HZSM-5 molecular sieves. The influence of physical and chemical properties of refined oil and chemical composition of aqueous phase and the anti-coking ability of modified HZSM-5 with the loading of Zn and P were studied. The results showed that the framework of modified HZSM-5 molecular sieves was not influenced by the modification of Zn and P, which were distributed on the surface of HZSM-5 uniformly. The BET of modified HZSM-5 were declined when Zn loading mass was increased. The physical and chemical properties of refined bio-oil when Zn loading mass was 3% were as follows: oxygen content was 10.67%, high calorific value was 36.76 MJ/kg, pH value was 5.85. Meanwhile, the relative contents of acids, alcohol and ether, aldehyde and ketone in aqueous phase were dropped significantly. Aromatic compounds and aromatic hydrocarbon were increased significantly with the ralative contents were 91.93% and 74.63% respectively. The anti-coking ability of modified HZSM-5 was enhanced with the P loading, which enhanced the stability of HZSM-5. Zn loading promoted the formation of carbenium ion and hydrogen transfer, which improved HZSM-5 molecular sieve aromatization performance.
Abstract: Zn/ZSM-5 zeolite catalysts with different Zn contents were prepared by impregnating method. The influence of reaction temperature, reaction time, catalyst dosage, and the acidic properties of catalysts on the conversion of γ-valerolactone to aromatic compounds was investigated.The results show that the introduction of Zn into H-ZSM-5 channel could effective modify the components of liquid product and influence the yields of gas, liquid, and solid as compared to H-ZSM-5 catalyst and non-catalytic conversion of γ-valerolactone. Zn/ZSM-5 catalyst affords the higher contents of aromatic compound compared to H-ZSM-5 and silica catalysts in the liquid product under identical reaction conditions. Therefore, Zn species of Zn/ZSM-5 can not only effectively improve the conversion of γ-valerolactone, but also enhance the formation of aromatic compounds, suggesting that Zn species play a very key role in the formation of these aromatic compounds.
Abstract: A series of nickel catalysts were prepared by the impregnation and co-precipitation methods and characterized by X-ray diffraction, nitrogen physisorption, and H2 temperature-programmed reduction. The effects of nickel loading, calcination temperature, reaction temperature, support modification and cobalt oxide addition on the catalytic activity and selectivity to H2 in the steam reforming of ethylene glycol were investigated. The results indicate that the nickel catalyst prepared by co-precipitation has smaller particle size and relatively higher activity in comparison with the catalyst prepared by impregnation. Adding a small amount of cobalt oxide to the Ni/CeO2 catalysts can enhance the catalytic activity; over the Ni-Co bimetallic catalyst, the yield of hydrogen reaches 72.6%. Modifying CeO2 with Al2O3, TiO2 and ZrO2 also has a certain influence on the catalytic activity and the Ni/CeO2-Al2O3 catalyst exhibits the highest activity, with an ethylene glycol conversion of 94% to gaseous products and a hydrogen yield of 67.0%. However, Ni/CeO2-SiO2 shows a very low activity in spite of its large surface area and pore volume.
Abstract: The pine powder gasification was conducted in a bench-scale entrained flow reactor. The influences of temperature,oxygen equivalence ratio and steam/biomass ratio on the composition of the gaseous products, carbon conversion, gas yield, LHV, morphology and composition of solid products were studied. The results show that when the reaction temperature increases gradually, the concentrations of CO and H2 rise dramatically and the concentrations of CO2 and CH4 significantly decrease. The carbon conversion, gas yield, and LHV also improve slightly. With a rise of oxygen equivalence ratio from 0.2 to 0.5, the concentrations of CO and H2 decrease by over 10%, the concentration of CO2 increases by 100%, and the carbon conversion reaches to 92.9%. Simultaneously, the gas yield also increases slightly, while the LHV exhibits opposite trends. When the steam/biomass ratio increases from 0 to 0.58, the H2/CO volume ratio grows gradually from 0.63 to 1.40. At the same time, the carbon conversion, gas yield and LHV first increase slowly then decrease rapidly. The analysis by scanning electron microscopy shows that the solid residue of gasification mainly consists of particles and fiber reunion. With increasing reaction temperature, the shape of particles in the solid residue changes gradually from irregular to spherical, while the higher oxygen equivalence ratio makes the number of pores and slits on particles increase rapidly and leads to the breaking of the particles.
Abstract: The influences of water-leaching and different concentration acid-leaching pretreatments on physicochemical properties and steam gasification reaction characteristics of rice straw (RS) were investigated in a laboratory fixed-bed reactor. The results show that after water-leaching, the potassium and sodium in RS are removed by 90.5% and 82.1%, respectively, and after acid-leaching, the removal of potassium from RS reaches to 99.2%, and the removal efficiency of sodium with acids is between 84.6% and 92.3%. Acid leaching does not change the main component content of RS, but destroys the microscopic structures of RS. The order of different concentration acid-treated RSs with respect to the three indexes including pore volume, pore diameter distribution and specific surface area is: all water-leached RS > 3% sulfuric acid-treated RS > raw RS > 7% sulfuric acid-treated RS > 10% sulfuric acid-treated RS. As the concentration of various pretreatment acids is 3%, the sulfuric acid-treated RS has the largest values of the three indexes and the phosphoric acid-treated RS has the smallest values of the three indexes. The steam gasification results show that potassium, sodium and abundant pore structure all can promote hydrogen generation, and the effects of potassium and sodium on gasification process are significantly stronger than pore structure. The H2 and CO2 instantaneous release concentration for water-leached RS is higher than that for acid-treated RS during gasification; however, it is contrary to CO and CH4. When the four acids concentration is 3%, there is a positive correlation between H2 and CO2 instantaneous release concentration and the pore diameter distribution; and there is a negative correlation between CO and CH4 instantaneous release concentration and the pore diameter distribution. The more abundant the pore, the faster the gasification rate. Though deashing pretreatment decreases the H2 production, it increases the calorific value of gasification gas.
Abstract: The activated carbon adsorbent was modified with tetrafluoroboric acid (HBF4) by impregnation and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and N2 physisorption. The performance of modified activated carbon in adsorption desulfurization of dibenzothiophene (DBT) in model diesel fuel was investigated and the influences of HBF4 concentration, calcination temperature and the initial DBT concentration on the sulfur removal efficiency were considered. The results show that the adsorbent modified with 0.5% HBF4 solution and calcined at 140 ℃ performs best in DBT desulfurization; when the adsorbent/oil ratio is 1:100, the HBF4-modified adsorbent exhibits an adsorption capacity of 352 mg/g, which is 72.5% higher than that of the unmodified activated carbon.
Abstract: HY zeolite obtained from NH4Y was characterized by N2 physisorption, NH3-TPD, and in-situ Py-FTIR. The adsorption, desorption, and conversion of methylthiophene on the HY zeolite was investigated by using the intelligent gravimetric analysis (IGA) and temperature programmed desorption-mass spectrum (TPD-MS). The results indicated that 2-methylthiophene and 3-methylthiophene are strongly chemisorbed on the strong Brnsted acid sites of HY zeolite, which promote the disproportionation, dealkylation and cracking reactions at 200 ℃. Compared with 2-methylthiophene, 3-methylthiophene is prone to crack and form 3-methyltetrahydrothiophene via the hydrogen transfer reactions.
Abstract: Adsorbents were successfully prepared by the liquid-phase ion-exchange Y zeolites with Ag, Ce and combined Ag-Ce metal ions.The adsorbents were characterized by the X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis), N2-adsorption specific surface area measurements (BET), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectrum analysis (XPS) and Fourier transform infrared (FT-IR). With thiophene/benzothiophene/1-octane/toluene model oil as feedstock,the effect of preparation and adsorption conditions of AgCeY adsorbent on desulfurization and its recycling use performance were investigated. The results show that the Ag and Ce species which are loaded on AgCeY zeolite exist as Ag+ and Ce4+. AgCeY not only has the high sulfur adsorption capacity similar to AgY but also has the higher selectivity for sulfur compounds similar to CeY. And the adsorption affinity of AgCeY follows in the order: benzothiophene > thiophene. The AgCeY adsorbent exchanged the Ag+ first, then the Ce3+, with a Ce/Ag mole ratio of 2.5 for 24 h, at 500 ℃ exhibited the best performance. With oil 20 mL, AgCeY 0.2 g, at 50 ℃ adsorbed for 60 min, the TP and BT uptake reach 59.0% and 96.5%, respectively.
Abstract: A series of metal oxides were employed to modify the commercial SCR catalyst, and the Ce modified SCR catalyst was selected and then subjected to detailed catalytic oxidation of Hg0 by using the simulated flue gas. The results indicated that the catalytic activity of the catalyst was increased remarkably after the Ce modification, and the highest catalytic oxidation of Hg0 was obtained from the modified SCR catalyst with 9% Ce loading, being 40% higher than that of the non-modified SCR catalyst. The BET and XRD analysis indicated that the surface area of the 1%~9% Ce modified SCR catalyst was no significant change compared with the non-modified SCR catalyst, and the CeO2 was well dispersed on the catalyst surface, without any aggregation. The flue gas condition had great effects on the Hg0 conversion. The catalytic oxidation of Hg0 would be significantly increased by HCl, and also increased as the increasing of the temperature in a certain range. The highest catalytic oxidation efficiency reached 95.11% at the optimal space velocity, temperature and flue gas components. In addition, the CeO2 doping did not affect the denitration efficiency of the SCR catalyst.
Abstract: Cu, Co, Mn and Ni decorated Fe2O3/Al2O3 oxygen carriers were prepared by freeze-drying method in this work. Temperature programmed reduction (H2-TPR) and Temperature programmed oxidation (TPO) experiments were conducted in an automatic chemisorption instrument, and the reactivity of transition metal decorated Fe2O3/Al2O3 oxygen carriers with H2 and O2 was evaluated. The results showed that the reactivity for oxygen carrier with H2 was improved after decorated with Cu, Co and Ni. But when decorated with Mn, the reactivity and oxygen transport capacity of oxygen carrier decreased. The Cu-decorated Fe2O3/Al2O3 oxygen carrier demonstrated the best reactivity with H2 and favorable stability. Therefore, it could be a potential oxygen carrier for using in the chemical looping combustion.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
