Abstract: The behavior of two direct coal liquefaction residues under pyrolysis conditions were carried out using thermogravimetric analysis, temperature programmed pyrolysis technique and FT-IR analysis. The optimized conditions for oil recovery from the residues were also studied. The oil yields from the pyrolysis of liquefaction residues (SHR and SLR) of Shenhua and Shengli coals at 450℃~500℃ are 32% and 20%, respectively. An increase in pyrolysis temperature above 450℃ has no effect on the oil yield, but makes the asphaltene content in oil arise. The hexane soluble fraction is a main fraction in the oil from SHR, while the oil from SLR contains about 50% of asphaltene. The hexane soluble fraction in SHR is not obviously polymerized during pyrolysis, while that in SLR is significantly polymerized during pyrolysis and resulted in an increase in asphaltene yield. At 400℃~500℃ the asphaltene fraction of both residues tends to release as oil, and companied with the increase of preasphaltene and tetrahydrofuran insoluble fractions especially for SLR.
Abstract: The pressurized fast pyrolysis of Jincheng anthracite was studied in a thermogravimetric fixed-bed reactor. Combined with the thermogravimetric analysis of coal chars gasification by TGS-2, the influence of pyrolysis temperature, residence time and pyrolysis pressure on the characteristics of residual were investigated. The results show that the char yield, the gasification activity, as well as the activation energy are greatly affected by the pyrolysis temperature, residence time and pressure. The BET surface area of the char is high under the long residence time and high pressure, and is low at high temperature. There is not close relationship between the BET surface of the char and its gasification rate. The gasification rate in steam is about three times larger than that in CO2.
Abstract: The influence of kaolinite additive on the emission characteristics of PM2.5 (particulates with aerodynamic diameter less than 2.5μm) was studied with a tube furnace. The combustion tests were carried out at 1123K under O2/CO2 atmosphere. The PM2.5 generated from coal combustion was collected and analyzed with an Electrical Low Pressure Impactor (ELPI). The results indicate that kaolinite is an important factor for the formation of PM2.5 during coal combustion under O2/CO2 atmosphere. The number and mass concentrations of PM1 diminish, but those of PM1~2.5 enhance slightly after kaolinite is added. The size distributions of PM2.5are similar, which display two peaks around 0.2μm and 2.0μm, respectively. With increasing the weight ratio of kaolinite, the concentrations of S, Pb, Cu, Na and K decrease. The submicron-size ash particles smaller than 0.317μm are formed via nucleation of vaporized ash components. The supermicron-size ash particles are formed by coagulation and coalescence of the submicron-size ash, and fragmentation and coalescence of mineral matter.
Abstract: The decomposition of formic acid (0.05mol/L~0.70mol/L) in supercritical water was investigated under 550℃~650℃, 24MPa~30MPa, and a residence time of 16s~46s. The results showed that the gaseous products from the decomposition are mainly H2, CO2 and CO; the yields of H2 and CO2 are much higher than that of other products. High temperature is in favor of H2 production, while the pressure exhibits less effect on formic acid decomposition at high temperature (> 600℃). With the increase of the residence time from 16s to 20s, the molar fraction H2 in the gaseous products is increased steadily, along with the rapid increase of carbon gasification efficiency. The reaction routes are dependent largely upon the feedstock concentration. With a low concentration of formic acid in the feed (＜ 0.1mol/L), the decomposition includes decarboxylation and dehydration routes; the former is the dominant pathway. Higher formic acid concentration may bring on many sidereactions. Alkaline additives are harmful for the hydrogen production from formic acid decomposition.
Abstract: The decomposition of toluene over a biomass char packed bed was studied with microwave heating(MH) and electrical heating(EH). The effects of temperature, atmosphere and retention time on the decomposition behavior and the product properrties of gas and solid were investigated. The results show that the toluene decomposition rate increases with the increase of temperature in the range of 600℃～800℃. At 700℃, the conversion of toluene is 92.7%, 97.8% and 93.9% in N2, steam and CO2 atmospheres, respectively with MH, while the conversion of toluene with EH is 59.2%, 59.7% and 59.4%, respectively. The retention time has a slight effect on the toluene conversion. The selectivity of the product H2 strongly depends on the heating method. The selectivity of H2 under MH is about 15% higher than that under EH. Nanofibers are formed on the surface of the char under MH, while only amorphous carbon is found on the char under EH. XRD analysis of biomass char implies that the hot spots effect may take place under MH.
Abstract: A novel solid base catalyst, CaO/MgO/Fe3O4 with magnetism used for production of clean biodiesel, was prepared and characterized by X-ray diffraction, transmission electron microscope, infrared spectrum and magnetism analysis. The catalytic activities of the fresh and the reused catalysts for the transesterification of peanut oil with methanol to produce biodiesel were investigated. The magnetic support of MgO/Fe3O4 with MgO loading of 5% was obtained by the magnetic matrix Fe3O4 dipped in Mg(Ac)2 aqueous solution and then calcined at 600℃ in N2. And CaO/MgO/Fe3O4 with CaO loading of 10% was prepared by MgO/Fe3O4 impregnated in Ca(Ac)2 aqueous solution and further calcined at 700℃ in N2. The particle of CaO/MgO/Fe3O4 was shell-core structure with the core mean diameter of 35nm. The results show that CaO/MgO/Fe3O4 has higher catalytic activity for transesterification reaction and could be separated easily from the reaction products in magnetic field. Both the conversion of peanut oil and recovery of the catalyst are above 90% under the conditions of atmospheric pressure, 65℃ for 2h, methanol/oil mol ratio of 12, and catalyst dosage (catalyst/oil) of 10%. The falling off of CaO from CaO/MgO/Fe3O4 during stirring reaction process was speculated as one of the reasons for the lower activity of the reused catalyst.
Abstract: The effects of three free radical initiators including azodiisobutyronitrile (AIBN), Di-tert-butyl peroxide (DTBP) and iodine (I2) on the hydrocracking of Kelamayi vacuum gas oil (KVGO) and Gudao vacuum residue (GDVR) were investigated in an autoclave-style reactor. The effects of the amounts of initiator and catalyst added and the reaction temperature on the hydrocracking were examined under an initial H2 pressure of 7.0MPa (reaction time, 1h). The results indicated that the conversion of heavy oil, the yield of light distillates, and the extent of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) are improved largely by the addition of the initiators for hydrocracking. By adding 5000×10-6 or 10000×10-6 initiator in the feed, the yield of light distillates can be increased by 10% or 13% and the extent of HDS and HDN is increased by about 11% or 7%, respectively. DTBP and I2 are better initiators in the hydrocracking than AIBN. An analysis of the cracking-products reveals that the addition of initiators is favorable for the formation of the primary crackingproducts with VGO or vacuum residues as the hydrocracking feed.
Abstract: The photocatalytic oxidation of dibenzothiophen (DBT) in octance (as solvent) was conducted using O2 in air as the oxidant, TiO2 prepared by sol-gelatin method as the photocatalyst and coupling with ultrasonic. The effect of light distance, photocatalyst amount, reaction time, DBT initial concentration and ultasonic power on the removal of DBT were investigated deeply. The results show that the degradation rate of DBT increases by 10% by using ultrasonic. Under the conditions of TiO2 dosage of 2g/L, air flow rate of 800mL/min, distance of UV light of 20cm, initial concentration of DBT of 600mg/L, reaction time of 150min, ultrasound power of 500W, the degradation rate of DBT can reach up to 72.6%.
Abstract: Taking tungstophosphoric acid as the catalyst, the removal of dibenzothiophene(DBT) remained in n-heptane using organic peroxide coupling ionic liquid was studied. The results indicate that the removal of sulfur is only about 27.78%~38.76% by using \[bmim\]BF4 or \[bmim\]PF6 ionic liquid (IL) as an extractant alone for the DBT-containing model oil. While 76.6% of DBT can be oxidized to dibenzothiophene sulfone by using the organic peroxide made from organic formic acid and H2O2 in equal volume as oxidants at 70℃ and the reaction time of 6h without catalyst and ionic liquids. As the system contains tungstophosphoric acid, organic peroxide and \[bmim\]PF6 ionic liquid, the catalytic oxidation and sulfur removal are improved apparently. The DBT removal reaches 98.60% at 70℃ and the reaction time of 6h when the molar ratio of catalyst to DBT, the volume ratio of oxidant to DBT and the volume ratio of \[bmim\]PF6 ionic liquid to DBT are 0.20∶1, 10∶1, 1∶1, respectively. The coupling system could be recycled five times without significant decrease in activity.
Abstract: Catalytic oxidation is an important means for deep desulfurization of oil products. In order to meet more stringent specifications of sulfur contents in oil products, studies on desulfurization methods with more selective and more active catalytic oxidation have become a hot subject. A quaternary ammonium phosphotungstate was prepared by hexadecyl trimethyl ammonium bromide and phosphotungstate. The prepared catalyst was characterized by FT-IR and SEM. The method of producing low sulfur gasoline was proposed using hydrogen peroxide as oxidant and the above catalyst. The effects of the extractants, oxidation and extraction conditions on desulphurization were examined. Under the conditions of gasoline 10mL, hydrogen peroxide 0.01mL, catalyst 0.0016g, oxidation reaction was performed at 30℃ with 60min. Using the multiplex solvent LJ-1 as the extractant and the solvent/oil ratio of 1, the sulfur content of gasoline is reduced from 179.3mg/L to 10.8mg/L at 20℃ with 15min. The desulphurization ratio reaches to 94.0%, which is higher than that of gasoline extracted directly without oxidation by 45.6%. The catalyst is high selective and low in dosage, which will be potential in gasoline desulphurization. The oxidized desulphurization effect is remarkable.
Abstract: Copper-manganese mixed oxides were synthesized by co-precipitation with either KOH or NaOH as precipitators from CuSO4·5H2O and MnSO4·H2O as starting materials. The as-synthesized samples were tested for the water gas shift reaction and characterized by XRD, low temperature N2 absorption/desorption, TG and TPR. The obtained end precipitate consists mainly of Mn3O4 and Cu2+1O for samples prepared using NaOH as the precipitator whereas Cu4SO4(OH)6·H2O is obtained for the samples using KOH as the precipitator. Both the end precipitates prepared with NaOH and KOH as precipitators are converted to Cu1.5Mn1.5O4 after calcination, and reduced to Cu and MnO after the water gas shift reaction. Drastic differences are observed in their catalytic properties for the water gas shift reaction. The dry samples are composed of Mn3O4 and Cu2+1O when using NaOH as a precipitator and these samples maintain a relatively high texture stability and composition uniformity which ensure higher activity and thermal stability. However, for the layered structure of Cu4SO4(OH)6·H2O and the amorphous manganese oxide, the composition of the dry samples prepared with KOH as a precipitator shows that the samples undergo a complex evolution during calcination resulting in a weakening of the synergistic effect between copper and manganese. Therefore, under the water gas shift reaction conditions the stability of the texture and composition uniformity of the KOH precipitated sample decrease greatly, which leads to a decrease in activity and thermal stability. The present comprehensive study results show that the Cu-Mn mixed oxide prepared using NaOH as a precipitator has significantly higher texture stability and catalytic activity than that prepared using KOH as a precipitator, and present excellent thermal stability.
Abstract: The effect of Sn promoter on the performance of Pt-Sn/γ-Al2O3 catalysts for the long-chain paraffins dehydrogenation to monoolefins was studied by n-dodecane dehydrogenation. The catalysts were characterized by N2 adsorption-desorption, mercury intrusion porosimetry, CO pulse chemisorption, X-ray photoelectron spectroscopy and thermogravimetric analysis. Results show that the Pt-Sn/γ-Al2O3 catalysts exhibit the optimal catalytic performance when the Sn∶Pt (atomic ratio) of the catalyst is 3. While keeping on increasing the amount of Sn, the catalytic dehydrogenation activity of the catalysts is decreased with the formation of Sn0 and Pt-Sn alloy. Moreover, the catalytic stability of the catalysts is enhanced after the addition of Sn. And with the increasing of Sn loading, the selectivity to mono-olefins of the Pt-based γ-Al2O3 catalysts is also greatly increased.
Abstract: Dehydrogenation of isobutane to isobutene in the presence of carbon dioxide was carried out over NiO/Al2O3 catalyst and the effect of K2O additive on its catalytic behavior was investigated. Compared with the reaction in an inert atmosphere, the dehydrogenation of isobutane is coupled with the reverse water-gas shift by conducting the reaction in carbon dioxide, which can then enhance the isobutene yield. The addition of K2O in the NiO/Al2O3 catalyst can decrease its acidity, alleviate the deep reduction of NiO active species during the reaction and then suppress the side reactions like cracking and coke formation; these are helpful to enhance the isobutene yield and to improve the catalyst stability.
Abstract: Cu/ZrO2 catalysts were prepared through fractional precipitation, impregnation-precipitation and solid-state reaction methods and characterized by N2 sorption, XRD, TPR, in-situ IR and XPS techniques. Their catalytic performances in methanol synthesis from CO2 hydrogenation were investigated. The results showed that the physical structure and reducibility as well as the interaction between Cu and ZrO2 of a Cu/ZrO2 catalyst are greatly affected by the preparation method. The catalytic performance of Cu/ZrO2 is mainly determined by the interaction between Cu and ZrO2 rather than by the surface area. Compared with the catalysts prepared by other methods, the Cu/ZrO2 catalyst prepared by impregnation-precipitation is provided with higher CuO dispersion and stronger interaction between Cu and ZrO2; it also exhibits higher CO2 conversion and higher methanol yield when used as catalyst in the synthesis of methanol from CO2 hydrogenation.
Abstract: A series of Mg-Ni/BaTiO3 catalysts (Ni/BaTiO3 promoted by MgO) were prepared by impregnation method; their catalytic activity for CH4/CO2 reforming to syngas was examined with a fixed bed reactor. The results showed that Mg-Ni/BaTiO3 catalyst with an MgO loading of 5% performs best in CH4/CO2 reforming. The sequence for impregnation during the catalyst preparation may also influence the activity of resultant catalyst; Mg should be impregnated prior to Ni to get high active Mg-Ni/BaTiO3 catalyst. Compared with Ni/BaTiO3, the addition of MgO promoter can enhance its catalytic activity and resistance to carbon deposition for CH4/CO2 reforming.
Abstract: MgO-ZrO2 had been synthesized from cheap materials Zr(NO3)4 and Mg(NO3)2 using poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (P123) as template. The structure and surface properties of the as-prepared materials were characterized by XRD, N2 adsorption/desorption and CO2-TPD techniques. The results demonstrated that material contain typical mesoporous characteristics and can be recycled without considerable decrease of CO2 adsorption capacity. The material can be recycled in multicycle CO2 adsorption/desorption application. The material has a typical solid solution structure, special basic site form with Mg2+ entering into the lattice of tetragonal ZrO2 and replacing Zr4+. The basic site with a solid substrate is not easy to lose. The ability of working at CO2 temperature as high as 150℃, with the high adsorption velocity （0.084mmol/(g·min)）and capacity（1.01mmol/g）makes MgO-ZrO2 solid base to be a very promising CO2 acceptor for effective applications.
Abstract: The characteristics of different Ca-based CO2 absorbents in the process of cyclic calcination-carbonation were investigated. The variation of microstructure, pore radius and specific surface area of the absorbent with different crystal lattice configurations during the cycles was researched, and the main reason that affects the reactivity of the absorbent was analyzed. The results show that the stability of CO2 capture capacity of the calcined dolomite is higher than that of the calcined limestone. Dolomite includes MgO that can change the atomic framework of the absorbent, in turn reduce the plugging of the pore due to the formation of CaCO3 and keep the reactivity of absorbent.
Abstract: To investigate the effect of zeolite crystal size on the reaction of methanol to light olefins (MTO), two groups of catalysts with nearly the same acidity were obtained by modification of three kinds of HZSM-5 zeolites with Ca. Na was also used as a reference modifier to investigate the role of Ca in MTO. The crystal size and morphology of the catalysts were characterized by SEM and the acidity was measured by NH3-TPD and Py-IR. The results showed that for MTO over HZSM-5, the selectivity to light olefins is low; moreover, the conversion of methanol as well as the selectivity to light olefins decrease quickly with time on stream. The selectivity to light olefin and the catalytic stability of HZSM-5 is increased significantly by the modification with Ca, especially at high Ca loading. Na modification may enhance the selectivity to light olefins, but the conversion of methanol over Namodified HZSM-5 still decreases quickly with the time on stream. The catalysts (either HZSM-5 or Ca/HZSM-5) with smaller crystal size also exhibit better stability. The MTO performance of HZSM-5 catalyst is affected both by the acidity and by the crystal size. Ca-modified HZSM-5 with lower acidity exhibits higher catalytic stability and higher selectivity to light olefins, which may be ascribed to that Ca is involved in the MTO cycle via both acidic and basic sites in the Ca-modified HZSM-5. Small crystal size is favorable to enhance the catalytic stability.
Abstract: Perovskitetype SrTi1-xLixO3-δ(x = 0, 0.025, 0.050) nano catalyst was prepared by using sol-gel method. Its structure was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), in-situ electron spin resonance (ESR), and temperature-programmed surface reaction (TPRS); its catalytic performance for oxidative coupling of methane (OCM) was measured in a microreactor. The results indicated that the OCM catalytic performance at low temperature (about 650℃) is enhanced by doping Li+ cation to the B site of perovskitetype SrTiO3 nano catalysts; the SrTi1-xLixO3-δ nano catalyst with x = 0.025 performs best. Compare with the conventional catalysts of the same composition prepared by citric acid method, SrTi0.975Li0.025O3-δ nano catalyst performs much better for OCM reaction at low temperature; higher C2 selectivity is achieved at the same temperature. In-situ ESR results showed that there exist O- with ESR signal at g = 2.0430 and F center with ESR signal at g = 2.0080 in the nano SrTi0.975Li0.025O3-δ catalyst, while the conventional SrTi0.975Li0.025O3-δ catalyst shows O2- with the ESR signals at g∥ = 2.014 and g⊥ = 1.9906. The high catalytic performance of SrTi0.975Li0.025O3-δ nano catalyst is related to F centers due to the low coordination surface atoms on the nano oxide particles. F center may activate CH4 at lower temperature and lead to the formation of C2 hydrocarbons with higher selectivity.
Abstract: USY zeolite was modified by dealuminization with oxalic acid. The effects of oxalic acid amount used for the modification on the relative crystallinity, SiO2/Al2O3 molar ratio, specific surface area, pore structure, acidity, and performance in decane hydrocracking of the resultant USY were investigated. The results showed that accompanying with the leaching of non-framework aluminum, some framework aluminum is also leached out from the modified USY zeolite; therefore, with the increase of the oxalic acid amount used, the SiO2/Al2O3 ratio of the modified USY is increased, the acidic strength and acidic amount are decreased, while a maximal relative crystallinity is obtained at a moderate amount of oxalic acid. For the hydrocracking of decane over the USY zeolite modified by oxalic acid of 0.2 (mass ratio), the conversion of decane and the selectivity to primary cracking products are 68.5% and 80.1%, respectively. The high hydrocracking activity of the modified USY can be attributed to its mesoporous structure and abundant accessible acidic centers; moreover, the large pores is also favorable for the diffusion of primary cracking products to avoid secondary cracking, which may also enhance the selectivity of primary cracking products.
Abstract: The Zn doped SrTiO3 photocatalysts were synthesized and the photocatalytic activity of the doped samples for water decomposition to hydrogen was measured under the irradiation of a high pressure Hg lamp (400W). The influence of doping amount of Zn and the calcination temperature on the photocatalytic activity were investigated. The physical properties of catalysts with and without Zn doping were characterized using XRD, XPS, SEM and UV-visible diffuse reflectance spectra. The experimental results show that Zn doping greatly improves the photocatalytic activity of SrTiO3. The optimum molar doping amount of Zn is about 1%, and in this case, the suitable calcination temperature is about 950℃. Under this condition, the photocatalytic property of Zn doped SrTiO3 is 2.2 times higher than that of the undoped one. The characterization results indicate that 1% Zn doping does not change the crystal structure and crystal perfection properties of SrTiO3. However, doping element Zn is enriched on the surface of SrTiO3 sample. In addition, the crystal size increases within a certain range of Zn doping. It can be predicted that Zn2TiO4 is generated by the incorporated Zn reacting with the Ti-rich phase existed on the SrTiO3 surface, which leads to the decrease of the surface defect concentration of SrTiO3, and consequently increases the photocatalytic activity of Zn doped SrTiO3.
Abstract: The waste water from Fischer-Tropsch synthesis plant was treated by Fenton-UASB-Biological contact oxidation combined process. The results showed that the pretreatment of the waste water by Fenton oxidation can not only eliminate CODCr by 63%, but also improve its bio-degradability effectively when the pH was 3, reaction time were 120min and dosage of H2O2 and Fe2+ was 30mL/L and 1.2g/L respectively; after treatment by UASB anaerobic, the CODCr removal rate could reach up to 90%; and finally after contact oxidation, the effluent CODCr was below 100mg/L, which can meet the second discharge standard of chemical waste water in GB8978-1996 Integrated Wastewater Discharge Standard.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
