Abstract: The reactivity of using Fe2O3 as an oxygen carrier during chemical-looping combustion (CLC) of coal has been investigated experimentally at 800℃~950℃. The experiments were carried out in a fluidized bed, where the steam acted as the gasificationfluidization medium. The reactivity of Fe2O3 as a function of the reactor temperature, reaction time, and cyclic reduction number was discussed. The reactivity of Fe2O3 oxygen carriers was enhanced as temperature increased at 800℃~950℃. Moreover, the time of chemical reaction control between the oxygen carrier and coal gasification products decreased with increased reaction temperature. When the reaction temperature was above 900℃, the rate of carbon to form CO2 was higher than 90%; however, it was lower than 75% below 850℃. At 900℃, the dry basis concentration of CO2 decreased with increased cyclic reduction period, while that of CO and CH4 increased. Moreover, the value of the CO concentration was less than that of CH4. The performance of the reacted Fe2O3-based oxygen carriers was also evaluated using an X-ray diffractometer and a scanning electron microscope to characterize the solid residues of oxygen carrier. The results show that Fe2O3-based oxygen carriers are only reduced to Fe3O4. With the increase of cyclic reduction period, the oxygen carrier sinters gradually.
Abstract: The coal ash fusion characteristics of high fusibility coal blending with two low fusibility coals respectively were studied. The data were analyzed using quantum chemistry methods and experiment from micro- and macro-molecular structures. The results show that Ca2+, as the electron acceptor, easily enters into the lattice of mullite, causing a transition from mullite to anorthite. Mullite is much more stable than anorthite. Ca2+ of anorthite occupies the larger cavities with the [SiO4]4- tetrahedral or [AlO4]5- tetrahedral rings respectively. Ca atom linked O weakens Si—O bond, leading ash fusion point to reduce effectively. The chemistry, reactivity sites and bond-formation characteristics of minerals can well explain the reaction mechanism refractory minerals and flux ash melting process at high temperature. The results of experiment are agreed with the theory analysis by using ternary phase diagrams and quantitative calculation.
The REE distribution between soluble hydrocarbons and minerals in a middle rank coal from Weibei, Shaanxi province, China, was studied with statistics method. It was found that there is a clear complementary relationship of REE between the soluble hydrocarbons and minerals. Among them, LREE and HREE have different distribution characters respectively, which are determined by the change of ions radii and inner electronic configuration. For this reason, the bigger atomic number of LREE, the less regularity of LREE distribution in soluble hydrocarbons and minerals. It is opposite for HREE. The complementary correlation or synchronous growth and decline with REE, are also observed among ingredients in the soluble hydrocarbons. This may have potential effect on the coal-formed hydrocarbons. This is another expression of “geochemical effect of REE in coal” observed by the author. In addition, the “tetra-component effect” of REE geochemistry in coal has been found.
Abstract: The influence of pre-treatments on apparent viscosity of blue-green algae, the maximum solids loading, rheological property and static stability of the coal-algae slurry was examined. The results show that chemical treatment, agitate and heating are useful pre-treatment methods. The apparent viscosity of bluegreen algae is declined from 72mPa·s to 21.8mPa·s (sharing rate 100s-1). The decrease in the apparent viscosity of blue-green algae is due to the structure of blue-green algae destroyed, which is favorable for the increase in the maximum solids loading of coal-algae slurry. When the mass ratio of water and blue-green algae is 1∶1, the maximum solids loading of coal-algae slurry could reach to 60%, which meets the industry requirement. After blue-green algae is added to coal-water slurry, the sediment time of coal-algae slurry is changed from 4h to 72h. Coal-algae slurry is a pseudo-plastic liquid, which is shear-thinning and easy to transport.
Abstract: Three biomass and one lignite were co-pyrolyzed in a thermogravimetric analyzer to investigate the pyrolysis performance of each material, as well as their mixtures. The lignite was blended with biomass at the percentage of 10%, 20%, 35% and 50% respectively. The results show that the initial volatile releasing temperature and the first maximum peak temperature of co-pyrolysis increase with increasing amount of lignite in blends. The position of the second maximum peak is shifted to lower temperature as the percentage of biomass is raised. Co-pyrolysis of coal/biomass blends produces more char than the summation of individual lignite and biomass pyrolysis. The pyrolysis of demineralization and devolatilization rice straw show that the alkali and alkaline earth metals promote pyrolysis of the blends at lower temperature, while Si inhibits the pyrolysis rate. Both volatile and mineral matter in biomass interact with lignite in co-pyrolysis. The synergistic effects in the copyrolysis of biomass and coal are suggested.
Abstract: The cracking of ethylene as one of the major components of oil refinery over a bed of Binxian char and quartz, respectively, has been studied in a fixed bed reactor at temperatures between 850℃ and 1000℃ and atmospheric pressure. The results show that the conversions of ethylene increases with increasing temperature. The products of ethylene cracking are H2, CH4, C2H6 and C. The higher the reaction temperature, the more complete ethylene cracking and the more H2 produced. The higher initial conversion rate of ethylene cracking at 850℃ to 950℃ is only observed over Binxian char but not on quartz and an empty reactor. This indicates a significant catalytic effect of Binxian char on ethylene cracking. Ethylene conversion decreases with reaction time due to carbon deposition on the char surface. The conversion of ethylene is 94% over quartz and in the empty reactor at 1000℃, suggesting that ethylene can completely decompose through thermal cracking without catalyst.
Abstract: The catalytic pyrolysis of FCC gasoline was investigated in a confined fluidized bed reactor with a specially developed catalyst to maximize the production of light olefins. The experimental results show that the reaction temperature is a key factor to the conversion and the total light olefins yield. The yields of total light olefins vary a little with the increase of catalyst-to-oil weight ratio and steam-to-oil weight ratio. As the weight hourly space velocity goes up, the yield of total light olefins decreases slightly. The optimal reaction conditions were determined for the catalytic pyrolysis of FCC gasoline, and the optimal reaction temperature, catalyst-to-oil weight ratio, weight hourly space velocity and steam-to-oil weight ratio are 660℃, 12, 15h-1 and 0.8, respectively. A reaction extent function of hydrocarbon catalytic pyrolysis was proposed on the basis of the relationship between the operating parameters and the product yields, and a correlation model of the product yields with the reaction extent function was established. As the value of the reaction extent function increases, the yield of ethylene keeps increasing, while the yields of propylene and total light olefins have their maximum.
Abstract: Oligomerization of ethene over ZSM5 catalyst was investigated on a fixed bed micro-reactor. The catalytic performance of HZSM-5 zeolite was markedly affected by the reaction conditions. Moderate reaction conditions can suppress secondary reactions and enhance the production of propene and butene. A slow deactivation accompanied by changes in the product distributions was observed along with the reaction time, which can be attributed to the coke deposition in the HZSM-5 pores during reaction. The conversion of ethene decreased gradually from initial 96.2% to 41.1% after 6h reaction, whereas the selectivity to propene and butene was increased during this period. Hydrogen transfer reaction was restrained at high space velocity, resulting in an increase of the selectivity to olefins. On the basis of the product distributions under different ethene conversions, a reaction pathway for ethene oligomerization was proposed. With the increase of the reaction temperature, ethene conversion increased first, reached a maximum value of 88.0% at 500℃, and then dropped; paraffins are dominated in the main product LPG. Raising the pressure of reaction system could promote the oligomerization of ethene, which was beneficial to ethene conversion, but unfavorable for yielding propene or butene.
Abstract: The WO3/SiO2 catalysts were prepared by impregnation (NH4)2WO4 onto SiO2 supports and their physicochemical properties were characterized by means of UV-Vis DRS and NH3-TPD. Effects of reaction conditions on the catalytic performance of WO3/SiO2 for metathesis of ethylene and 2-butylene to produce propylene were investigated. The optimal amount of WO3 loading was ~8%. Under the conditions of 473K~573K, 3.0MPa and 1.6h-1, the initial 2-butene conversion was higher than 80% with an exceeding 89.2% selectivity to propylene, using 8%WO3/SiO2 as the catalyst. It was shown that the 2-butene conversion and propylene selectivity decreased slightly during 140h continuous operation, and the metathesis activity of catalyst can be recovered through increasing the reaction temperature from 473K to 513K. The characterization revealed that three types of W+6 species (tetrahedral tungsten oxide species, octahedral polytungstate species and WO3 crystallites) were present in fresh WO3/SiO2 catalysts and the reduced form of tungsten oxide species (W+4, W+5 and W+(6-y) (0<y<1)) may be the suitable state of W species acting as metathesis active centers. NH3-TPD results demonstrated that new acid sites were introduced into the catalysts and the total amount of acidity was increased when SiO2 supports were loaded with WO3.
Abstract: In this study, LaNiO3 perovskite catalysts were prepared by citrate method and used for carbon dioxide (CO2) methanation. The catalysts were activated at different temperatures (400℃~700℃) under the reactant stream. The activation led to the formation of small metallic nickel particles and hexagonal lanthanum oxocarbonate (La2O2CO3). Ni0 was highly dispersed and enveloped by La2O2CO3, which was responsible for the high catalytic activity and stability of the LaNiO3 perovskite catalysts even at high temperature (400℃~500℃). The X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and H2-temperature-programmed desorption measurements illustrated that La2O2CO3 generated from the activation might play an important role in the methanation of CO2.
Abstract: The catalytic activities for CO methanation and adsorption performances of the Ni/SiO2 and Ni/ZrO2-SiO2 catalysts were investigated by a continuous flowing microreactor apparatus and in-situ diffuse reflectance fourier transform infrared spectroscopy. The results showed that CO was completely transformed at 200℃ under the reaction conditions: CO 1%、GHSV 5000h-1 and an atmosphere pressure over the Ni/ZrO2-SiO2 catalyst, while under the same reaction conditions the CO conversion was only 35% and CO was not completely transformed until 270℃ over the Ni/SiO2 catalyst, which suggested the catalytic activity of the Ni/ZrO2SiO2 catalyst increased with the addition of ZrO2 promoter. Meanwhile, the addition of ZrO2 promoter enhanced the adsorption capacity of the Ni/ZrO2-SiO2 catalyst for CO, and that in the presence of H2 a larger amount of bridged carbonyl hydride formed over the Ni/ZrO2-SiO2 catalyst at lower temperature, resulting in the increase of its catalytic activity. In CO methanation reaction, the breaking of C—O bond over those catalysts was via multi-hydrogen carbonyl hydride rather than via direct breaking.
Abstract: In this article, low-temperature selective catalytic reduction (SCR) reaction of NO on carbon nanotube-supported vanadium (V2O5/CNT) catalysts was carried out. When compared with activated carbon as a support catalyst, carbon nanotubes with low load of V2O5 show excellent catalytic activity than that of activated carbon, and the catalytic activity of V2O5/CNT catalysts increases markedly in the presence of SO2. The transient reaction experiment shows that the reaction of VV2O5/CNT catalyst for lowtemperature SCR of NO follows the mechanism of Eley-Rideal, namely by the reaction between the adsorbed NH3 and NO in the gaseous or a weakly adsorbed state.
Abstract: Mn-Ce-O/TiO2 and Cu-Ce-O/TiO2 phases were loaded onto the cordierite honeycomb ceramics using sol-gel method. A series of monolith catalysts with multilayer washcoat was prepared with different mass ratio of these two phases. The catalysts exhibit high activity at low temperatures and a wide temperature window for the selective catalytic reduction of NO with ammonia (NH3-SCR). NO conversion was 95% at 250℃ with the inlet NO concentration of 1025mg/m3, and the gas hourly space velocity (GHSV) of 12600h-1; the conversion of NO was above 80% in the temperature range of 200℃~300℃. The catalysts with multilayer washcoat performed much better in NH3-SCR than the single-phase catalyst. The results from BET, XRD, XPS, TPR, and SEM suggested that the high activity of these catalysts can be attributed to the large surface area, high loading of amorphous active components, TiO2 in the form of anatase, abundant surface cracks, and good redox capability of the multilayer structures.
Abstract: Au/Co-Al catalysts were prepared by using the ion-exchanged and co-precipitation methods, and their activities for the catalytic decomposition of N2O were tested. BET, XRD, and H2-TPR techniques were used to characterize the catalysts. The results show that the activity of Au/Co-Al catalyst prepared by using ion-exchanged method is higher than that using co-precipitation method. For the catalysts prepared by ion-exchanged method, the effects of preparation parameters, such as Au loading, pretreatment of HAuCl4 solution, and calcination temperatures, upon N2O conversion were investigated. The optimal preparation parameters of Au/Co-Al catalysts are that 1.1% of Au loading, pH value of HAuCl4 solution adjusted to 9.0, and 300℃ of calcination temperature. It is indicated that the addition of Na species in Co-Al mixed oxide promoted the reduction of Co3+ to Co2+ and enhanced the catalytic activity for N2O decomposition.
Abstract: A SCR catalyst was prepared with active components impregnation on the TiO2 made by sol-gel method. With TiO2 as the carrier, the effects of WO3 and V2O5 contents and SiO2 and Al2O3 addition on the DeNOx performance were investigated. It is demonstrated that the addition of SiO2 and Al2O3 can depress the DeNOx performance and 0.5%V2O5~10%WO3/TiO2 is the optimum catalyst within the investigating range. Compared with the commercialized catalyst that is mostly prepared by mixing uniform anatase TiO2 powder and glass fibers with binding to mold certain-shape support and then impregnating active components on the support, the catalyst of 0.5%V2O5~10%WO3/TiO2 shows an excellent NO removal efficiency below 603K, while the commercialized one shows more than 90% of DeNOx efficiency at 603K~663K, which can be attributed to the differences of preparation method and components.
Abstract: ZnHZSM-5 catalysts with different Zn loading were prepared by impregnation, and characterized by means of XRD, BET, NH3-TPD and Py-IR. The effects of Zn content and reaction parameters on the conversion of methanol to aromatics were investigated in a fixed-bed down-flow reactor. The results showed: The yield of aromatics increased by 5% on ZnHZSM-5 with Zn loading of 0.5%, but when the Zn loading was more than 2%, not only did the yield of aromatics decreased, but also the cracking reaction of methanol to carbon monoxide and carbon dioxide was enhanced. The highest aromatics yield among the Zn loading 1.0%～2.0%. The optimal LHSV and temperature were 0.36h-1～0.6h-1 and 350℃ respectively. Further more the procedure of the conversion of methanol to aromatics was discussed.
Abstract: The synthesis of dimethoxymethane (DMM) by selective oxidization of methanol over CuO supported rhenium oxide and manganses oxide as catalyst in a fix-bed reactor was studied. Combining with the characterization of XRD, H2-TPR and NH3-TPD, it was found that higher temperature may promote methanol conversion and the selectivity of DMM. With addition of manganese as structural promoter, the methanol conversion and the selectivity of DMM were improved. The catalyst could oxidize methanol to DMM by its lattice oxygen atoms without O2.
Abstract: The desulfurizers Mo and/or Ni-Mo supported on the phenolic resin-based activated carbon were prepared with water-soluble phenolic resin and metal salts as the precursors by a series of procedures including the reduced pressure distillation, solidification, carbonization, activation and presulfuration. The hydrodesulfurization of carbonyl sulfide (COS) on the as-prepared desulfurizers MSx-AC was investigated under different operation conditions (the metal used and its loading, reaction temperature, reaction time and COS feed concentration). The results showed that the water-soluble phenolic resin is an appropriate precursor for the preparation of AC supported catalysts for COS hydrodesulfurization. The catalytic activity of bimetal Ni-Mo/AC desulfurizer is higher than that of mono-metal Mo/AC. The hydro-conversion of COS on the MSx-AC desulfurizers is an internal diffusion control process, and a certain level of sulfur species in the reaction system is necessary to prohibit the presulfided desulfurizers from sulfur loss and then to maintain their catalytic activity.
Abstract: A series of K and Mn modified lanthanum hexaaluminates, K2MnxAl12-xO19-δ(x=0， 1.0， 1.5， 2.0， 2.5， 3.0) as new catalysts for combustion of methane, were prepared by means of reverse microemulsionhydrolysis of metal alkoxide and high temperature calcination. The structure and properties of the catalysts were characterized by XRD, DTA-TG, TPR and methane catalytic combustion reaction. Effect of Mn doping to substitute Al on the structure and methane combustion activity of K2MnxAl12-xO19-δ catalysts was investigated. The results showed that the catalyst with good crystallinity was obtained after calcination in oxygen at 1200℃. At the same time all catalysts have high catalytic activity. The introduction of different content of Mn ion show great effect on the properties of catalysts. The K2MnAl11O19-δ catalyst has higher activity with T10% at 458℃ and T90% at 676℃. Increased of Mn ions in precursor resulted in the formation of perovskite phase in the samples.
Abstract: Taking the activated carbon that was modified under 250℃ by concentrated sulfuric acid as support, a gasoline activated carbonbased desulfurization adsorbent MnO2/AC with MnO2 as active component was firstly prepared by impregnation. The effect of preparation and desulfurization condition on the desulfurization efficiency was investigated. The research results show that Mn(NO3)2 as the precursor, Mn(NO3)2 impregnation concentration of 0.15mol/L, the impregnation time of 24h under room temperature, the roasting temperature of 350℃ and the roasting time of 2h are the suitable adsorbent preparation conditions . The sulfur content of material gasoline can be reduced from 628.6×10-6 to 221.5×10-6 , which has the desulfurization efficiency up to 64.8% at the static adsorption temperature of 120℃, the adsorption time of 2h and the mass ratio of adsorbent to gasoline of 0.10; while the sulfur content in initial gasoline effluent after adsorption can be decreased from 628.6×10-6 to 21.8×10-6 and the initial desulfurization efficiency is 96.5% at the dynamic adsorption temperature of 60℃ and the LHSV of material gasoline of 1.76h-1.
Abstract: Cobalt complex of N, N′-bis(salicylidene) propane-1,3-diamine (Co(Salprn)) was encapsulated in the supercages of zeolite Y by the flexible ligand method. The encapsulated sample [Co(Salprn)]-Y was characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, infrared spectroscopy as well as differential-thermal analysis techniques. Its catalytic performance for the epoxidation of alkenes was investigated. The results indicted that the encapsulation does not have strong influence on the framework structure of zeolitic host and [Co(Salprn)]-Y prepared exhibits much higher catalytic activity than the neat Co(Salprn) complex in the epoxidation of styrene. The catalytic performance of [Co(Salprn)]-Y is affected significantly by the reaction conditions. Moreover, [Co(Salprn)]-Y is also catalytically active for the epoxidation of a variety of other alkenes; its activity decreases in the order of styrene > cyclohexene > cyclooctene > 1-octene.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
