Abstract: In order to make rational use of mild liquefaction solid product of Hami coal (MLS), the physicochemical properties of MLS were investigated, and the characteristics and interactive effects of MLS and its extraction fractions during pyrolysis were studied by thermogravimetric analyzer (TGA) in this work. The results show that MLS contains higher content of hexane soluble fraction (HS, 36%) than Shenhua direct liquefaction residue, but has the lower asphaltene (A, 13%) and preasphaltene (PA, 9%). The results of GC-MS show that HS consists of higher content of alkane (41.8%) and the results of infrared spectra indicate that the contents of alkane side chains and substituted functional groups decrease in the order of HS, A, and PA. Whereas, alkane side chains and substituted functional groups do not exist in THFIS, indicating its high aromaticity. The minerals in MLS are mainly CaCO3 produced by liquefaction process, and inert components of SiO2, NaCl, Al2O3·2SiO2·2H2O in raw coal and Fe1-xS, which is the product of catalyst. The results of TGA show that, compared with Shenhua direct liquefaction residue, the temperatures of initial decomposition and the maximum rate of mass loss of MLS are lower, however, the final mass loss (54%) up to 950 ℃ is higher, which suggest that the pyrolysis activity of MLS is higher. In addition, there are two kinds of interactive effects among the extraction fractions of MLS during pyrolysis, which are related to the amount of HS. When the content of HS is high, it can supply small free radicals and play a driving role for the evolution of volatile during the pyrolysis process. However, when the content of HS is low, large free radicals in MLS extraction fractions will combine with each other, which inhibits the release of volatile.
Abstract: Zunyi anthracite was used as the raw material of gasification and rice straw ash and cotton stalk ash were optioned as biomass ash additives. Char-CO2 isothermal gasification experiments were conducted using TGA to investigate the effect of biomass ash addition on coal char gasification characteristics. Furthermore, the relationship between char structure evolution during gasification and char gasification reactivity was investigated. The results indicate that the biomass ash addition has a promotion effect on coal char gasification, which is well related to the increase in active AAEM content and the decrease in the order degree of carbon structure of chars by the addition of biomass ash. However, the promotion effect of biomass ash additives on coal char gasification is weakened with increasing gasification temperature, mainly due to that the positive effect of biomass ash additive on the increase of active AAEM content in char and the inhibition effect of biomass ash additive on carbon structure order degree of coal char become weaker at higher gasification temperature. Additionally, it is found that cotton stalk ash has a more significant positive effect on coal char gasification than rice straw ash because cotton stalk ash has a more obvious effect on the increase in active AAEM content and the decrease in the carbon structure graphitization degree of coal char.
Abstract: Direct carbon solid oxide fuel cell (DC-SOFC) is a potential technology for generating electricity from solid carbon fuel with high conversion efficiency and low pollution. In this study, the use of industrial coke as a fuel for a direct carbon solid oxide fuel cell (DC-SOFC) was investigated. Tubular yttrium-stabilized zirconia (YSZ) electrolyte-supported solid oxide fuel cells (SOFCs) with a cermet of silver and gadolinium-doped ceria (Ag-GDC) as electrode material were fabricated. Raman spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy were applied to characterize the investigated coke fuels. It was observed that the coke fuel wa micron-sized particles with many structural defects, which favored the Boudouard reaction occurring in a DC-SOFC. A peak power density of 149 mW/cm2 at 850 ℃ was observed for pure coke fuel, and it improved to 217 mW/cm2 when a Fe-based catalyst was added to enhance the Boudouard reaction. The degradation performance of the DC-SOFC during a discharging test was analyzed according to the electrochemical characterization and emitted gas measurements. The performed test supported the feasibility of using coke as fuel in an all-solid-state DC-SOFC to generate electricity.
Abstract: MOF-199(Cu-BTC) was prepared and the ionic liquid supported MOF-199 adsorbents (Py/MOF-199) were successfully obtained via fixing ionic liquid[Hnmp] [H2PO4] onto the MOF-199. Adsorbents were characterized via XRD, FT-IR, SEM, and BET methods. The effects of pretreatment conditions of MOF-199, ionic liquid loading method, ionic liquid content, loading temperature and time on adsorptive removal performance of thiophene were studied. The preparation conditions of Py/MOF-199 adsorbent were optimized via orthogonal experiment, and the desulfurization conditions were also optimized. The results show that after the introduction of[Hnmp] [H2PO4] the regular octahedron structure of MOF-199 of Py/MOF-199 was maintained unchanged and the average pore diameter was increased. The optimal preparation conditions of Py/MOF-199 adsorbent are pretreating MOF-199 with Soxhlet extraction and drying in vacuum, then loading[Hnmp] [H2PO4] using solvothermal method, loading temperature of 50 ℃, loading time of 8 h, ionic liquid content of 7%. The influence of preparation factors on the desulfurization performance of adsorbent is in order:loading temperature > loading time > ionic liquid content. The optimal desulfurization conditions are model oil of 10 mL, Py/MOF-199 dosage of 0.2 g, adsorption under 70 ℃ for 1 h. Under these conditions, the thiophene desulfurization rate over Py/MOF-199 reached 96.7%.
Abstract: A series of ZSM-5 zeolites with different silica/alumina ratios were synthesized and characterized by means of XRD, FT-IR, ICP, SEM, NH3-TPD and N2 sorption; their performance in the removal of aniline and pyridine from a model fuel through adsorption was then investigated. The results indicated that all the as-synthesized ZSM-5 zeolites have the MFI structure, although the actual silica/alumina ratio in the as-synthesized ZSM-5 zeolites is somewhat lower than that in the corresponding synthesis mixture. As expected, the acid amount of ZSM-5 zeolites decreases with the increase of the silica/alumina ratio. The adsorption denitrogenation performance of ZSM-5(1) and ZSM-5(2) with relatively lower silica/alumina ratios is superior to that of other two zeolite samples; meanwhile, the removal efficiency for pyridine over all ZSM-5 samples is higher than that for aniline. Moreover, adsorption isotherms of aniline and pyridine over ZSM-5(2) accord with the Langmuir-Freundlich adsorption model.
Abstract: Al-based layered double hydroxides and corresponding mixed oxides were prepared and used as the supports for the Pt based catalysts; their catalytic performance in the hydrodeoxygenation (HDO) of p-cresol was then investigated. The results indicate that the catalytic performance of Pt based catalysts is related to the composition and structure of the support; Pt directly supported on the Al-based layered double hydroxides exhibits higher activity in p-cresol HDO than that supported on corresponding mixed oxides. Especially, for the HDO at 275 ℃ and 2 MPa for 1 h, the conversion of p-cresol over Pt-Ni-Al-H is 99.8%, with a selectivity of 1.4% to toluene, whereas the selectivity to toluene over Pt-Zn-Al-H reaches 84.1%. Moreover, the Pt based catalysts are also active for the dehydrogenation of methylcyclohexane to toluene, which can effectively reduce the hydrogen consumption in HDO.
Abstract: The Pt/Al2O3, Pt/Al2O3-ZSM-5 and Pt/ZSM-5 catalysts were prepared and characterized by XRD, BET, SEM and NH3-TPD. The effects of crystal structure, acidity, pore size distribution and external shape of the three catalysts on the hydrodeoxygenation of fatty acid methyl esters were investigated under different reaction conditions. The results show that the Brønsted acidic sites and proportion of mesoporous volume were critical for the hydrodeoxygenation of fatty acid methyl esters. The Brønsted acidic site plays a major role in the C-O bond breakage of deoxygenation reaction, the mesopores improved the mass transfer efficiency of the entire reaction and avoided cracking of C12-18 long chain alkanes. The hydrodeoxygenation activity of the three catalysts were as follow:Pt/Al2O3-ZSM-5>Pt/Al2O3>Pt/ZSM-5. The optimal reaction conditions were as follow:t=350 ℃, p=2 MPa, H2/oil=1000, WHSV=0.5 h-1. Under the optimal reaction conditions, the fatty acid methyl ester conversion of Pt/Al2O3-ZSM-5 was 99.4%, and the liquid yield of the target product was 86.8%.
Abstract: Using copper hydroxide, nickel acetate and pseudoboehmite as materials, the Cu-Ni-Al spinel catalysts were synthesized by the solid-phase method. The effects of Cu/Ni/Al molar ratio and calcination temperature on specific surface area, phase composition, reduction performance and surface property of Cu-Ni-Al spinel catalysts were characterized by BET, XRD, H2-TPR and XPS. Moreover, the sustained release catalytic performances of Cu-Ni-Al spinel samples for methanol steam reforming were tested. The obtained results indicated that with increasing the calcination temperature, the content of Cu-Ni-Al spinel increased, but the size of spinel particles increased and the specific surface area decreased. Change of the calcination temperature and Cu/Ni/Al molar ratio led to different specific surface area, reduction performance and surface property of Cu-Ni-Al spinel catalysts, thus showing different sustained release catalytic performance. Comparing with those of stoichiometric ratio of Cu/Al=1:2, spinel solid solutions with smaller particle size, higher specific surface area and pore volume, more hardly-reducible spinel and better sustained release catalytic performance were obtained with the nonstoichiometric ratio of Cu/Al=1:3. The results of catalyst evaluation indicated that active copper species were released from Cu-Ni-Al spinel lattice and thus took part in the catalytic action. Among the prepared catalysts, CNA3-1000 catalyst showed the highest catalytic activity and stability.
Abstract: ZnCrOx composite oxide and HZSM-5 zeolite were prepared by using the coprecipitation and hydrothermal methods, respectively; after that, a bi-functional ZnCrOx/HZSM-5 catalyst was obtained through physical mixing of ZnCrOx with HZSM-5 and used in the direct synthesis of isoalkanes from syngas. The ZnCrOx/HZSM-5 catalyst was characterized by XRD, TEM, N2 sorption, and NH3-TPD and the effects of Si/Al ratio in HZSM-5 and the mass ratio of ZnCrOx to HZSM-5 (OX/ZEO mass ratio) on the catalytic performance of ZnCrOx/HZSM-5 in syngas conversion were investigated. The results indicated that with the increase of Si/Al ratio in HZSM-5, the catalyst acid density is decreased, resulting in a lower CO conversion but higher selectivity to C5+ products and higher isoparaffin fraction. Moreover, the selectivity to C5+ products is significantly increased by increasing the proportion of ZnCrOx components in the bifunctional catalyst without losing CO conversion. For the syngas conversion over ZnCrOx/HZSM-5 catalyst under the conditions of 400 ℃, 2.0 MPa, gas hourly space velocity (GHSV) of 3600 mL/(h·gcat), the conversion of syngas reaches 35%, with a selectivity of 44% to C5+ products and an isopentane fraction up to 65% in the C5+ products.
Abstract: A series of SAPO-34 molecular sieves with low Si/Al ratio were synthesized by conventional hydrothermal method as well as adding powder crystal seed and liquid crystal seed containing SAPO-34 precursor. These SAPO-34 molecular sieves were characterized by XRD, SEM, FT-IR and NH3-TPD and the effects of synthesis method on the structure, morphology, crystal size and acidity of the resultant SAPO-34 molecular sieves as well as their catalytic performance in the conversion of methanol to olefins (MTO) were investigated. The results indicate that although the seed form has little influence on the crystallinity, the silicon distribution in SAPO-34 framework, crystal size, and acidic properties are strongly related to the seed form. In comparison with the SAPO-34 sample synthesized with powder form seed, the SAPO-34 molecular sieves prepared using liquid crystal seed containing SAPO-34 precursor exhibit smaller crystal size, weaker acidic strength, and higher selectivity to light olefins in MTO.
Abstract: Ti-pillared interlayer clay (PILC)-based catalysts ion exchanged with Fe were prepared and used for selective catalytic reduction of NOx using propylene as the reducing agent under oxygen-rich conditions. The relationship between structure and properties of the catalysts was studied using N2-adsorption/desorption, XRD, UV-vis, H2-TPR, and Py-FTIR. The results show that the prepared 19Fe/Ti-PILC catalyst can achieve complete removal of NO at 400 ℃, and N2 selectivity can reach over 90% and has better resistance to water vapor and SO2. N2-isothermal adsorption/desorption and XRD results show that structure of montmorillonite is opened, cross-linked pillars are effective, and a large specific surface area and pore volume are formed. UV-vis results show that the denitrification activity of the catalyst is related to content of oligomeric FexOy. Py-FTIR results show that both Lewis acid and Brønsted acid are presented on the catalyst surface. Fe3+ loading into the pillared clay can significantly increase the Lewis acid content. Lewis acid is one of the influencing factors on the denitrification activity of the catalyst. H2-TPR indicates that the catalyst has a strong reduction ability at about 400 ℃, and the reduction ability of the catalyst is mainly represented by the reduction of Fe3+→Fe2+.
Abstract: Iron-pillared clays (Fe-PILC) were prepared by ion-exchange method and the iron species act as the pillaring components and active components and their performances for selective catalytic reduction of NO by propene were investigated under lean-burn conditions. XRD, N2 adsorption/desorption, H2-TPR, UV-vis, Py-FTIR, etc were used to characterize the catalysts. The results showed that 1.0Fe-PILC reduced more than 98% of NO at 450-600℃ and the selectivity for N2 reached 97%. The catalytic activity of the 1.0Fe-PILC was slightly influenced by water vapor and SO2. XRD and N2 adsorption/desorption characterization results showed that the iron species entered the Na-Mont interlayer and formed much larger specific surface area and pore volume. H2-TPR results indicated that Fe-PILC had a strong reduction ability at about 400 ℃, which represented the reduction of Fe3+→Fe2+. UV-vis results showed that the denitrification activity of Fe-PILC was positively correlated with the iron oxide oligomer FexOy. Py-FTIR results revealed that Lewis acid and Brønsted acid sites formed on the Fe-PILC surface. The main catalytic activity center of C3H6 and NO reaction was the Lewis acid site.
Abstract: The activity of SCR catalyst used in a coal-fired power plant for 24000 h was tested. With the help of XRD, BET, XRF, FT-IR and XPS, it is found that the catalyst has some problems such as micropore and mesopore plugging and the oxidation of active substances, which leads to the deactivation of the catalyst. Water washing and H2SO4 washing were used to remove plugs in the pores of the catalyst. The result shows that water washing can resume part of vanadium species and H2SO4 washing can renew the active sites on the surface of catalyst and uniformly load the sulfur species which can increase the acidity of active site. The SO2 sulphation treatment was performed on the catalyst after water washing. It is indicated that the Brønsted acid and the Lewis acid sites have higher strength and the Lewis acid has higher density than that by H2SO4 washing. After the regeneration treatment, H2SO4 washed catalyst activity is restored to the level of fresh catalyst above 250 ℃. And the activity of SO2 sulphation catalyst at 450 ℃ reaches 104.6% of the fresh catalyst activity at 380 ℃.
Abstract: A series of CuO/γ-Al2O3 catalysts were prepared by conventional impregnation and then modified with low temperature plasma at atmospheric pressure in a dielectric barrier discharge (DBD) reactor. These modified catalysts were used in the catalytic combustion of low-concentration methane. The effects of Cu loading and plasma modification process on the activity of CuO/γ-Al2O3 catalyst were investigated. The results show that the catalytic activity is the best when the loading of Cu is 7%. Modification gas and its space velocity, discharge voltage, discharge frequency, plasma treatment time are the factors that affect the activity of the catalyst. O2 plasma treatment has effect on increasing the activity of CuO/γ-Al2O3 catalyst, and N2 plasma treatment reduces the catalytic activity. When oxygen as the modification gas, the optimum modification process conditions are 45 kV of the discharge voltage, 14.71 kHz of the discharge frequency, 30 min of the plasma treatment time, and 20 mL/(min·g) of the oxygen space velocity. The catalyst, which is modified under the above process conditions, exhibits excellent catalytic activity for the combustion of low-concentration methane. Using this catalyst, t10, t50 and t90 are decreased by 23, 6 and 19 ℃, respectively. Compared with the conventional CuO/γ-Al2O3 catalyst, the plasma modified CuO/γ-Al2O3 catalyst can depress the apparent activation energy of the catalytic combustion reaction of low-concentration methane from 79.27 to 76.12 kJ/mol. The parent and modified samples were characterized by diverse techniques including SEM, BET, XRD, XPS and H2-TPR. The results show that the O2 plasma can adjust specific surface area, the electron density around atom Cu and mobility of bulk phase oxygen of the catalyst, thereby affect the adsorption, activation and conversion of methane on the surface of the catalyst in the combustion of low-concentration methane.
Abstract: In view of the problem of mercury re-emission in wet flue gas desulfurization system, Na2S, 2, 4, 6-trimercaptotiazine trisodium (TMT-18), sodium dithiocarbamate (DTCR-2) and Fenton reagents were added into the desulfurization slurry to study their effects on mercury re-emission. The results show that the 4 additives could effectively inhibit the mercury re-emission. 1.0 time stoichiometric ratio of Na2S is enough to combine with Hg2+ in the slurry into HgS. Thereby the ratio of mercury re-emission reduces to 5.27%. The optimum dosage of heavy metal chelating agents TMT-18 and DTCR-2 are 3.0 and 1.0 time stoichiometric ratio. They combine with Hg2+ to form organic chelate mercury and then fix it. So the ratio of mercury re-emission reduces to 5.09% and 4.62%, respectively. After adding Fenton reagent with a strong oxidizing into the slurry, the ratio of reduced mercury reduces to only 2.31% when H2O2 concentration is 0.3 mol/L and the ratio of[Fe2+]/[H2O2] is 1:8. Fenton reagent has the best effect on mercury re-emission in the simulated wet gas desulphurization slurry among 4 additives.
Abstract: To study the oxidative cracking process of tars during the combustion of syngas from MSW gasification, C6H6 was selected as the model compound, and the experiments of oxidation were carried out with and without Cl2 in a homogeneous tubular flow reactor coupled with FT-IR. The oxidative products and oxidative degree as functions of temperature and ER were compared to reveal the effect of chlorine on C6H6 oxidation. The results indicate that chlorine has a clear excitation effect on C6H6 oxidation at low temperature. However, a further oxidation to CO2 is inhibited by chlorine due to the increased OH consumption. Moreover, chlorine also promotes the polymerization reaction at high temperature and low equivalence ratio. Thus, the combustion of syngas from MSW gasification can proceed at lower temperature, while the environments with high temperature and low equivalence ratio should be avoided for the prevention of polymerization. Also, the chlorine content of MSW should be controlled to ensure the complete oxidation.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
