Abstract: The effects of KCl-ZnCl2 molten salt on the pyrolysis characteristics and pyrolysis products of heavy bio-oil at 400, 500 and 600℃ were studied. The results showed that molten salt increased the solid yield of heavy bio-oil pyrolysis and decreased the gas yield. Some compounds such as phenol, cresol, ethylphenol and 4-propylphenol had good enrichment effect, especially the relative concentration of cresol increased from 8.82% to 20.85% at 400℃, while the relative concentration of phenol increased from 2.18% to 8.62% at 600℃. During formation of char, molten salt reduced the content of carbon and increased the content of oxygen, increased the BET surface area and total pore volume of pores. Molten salt promoted formation of pore structure of the solid product and increased its average pore diameter.
Abstract: Due to the complex composition, large fluctuation of material characteristics and low energy density of MSW, the gasification characteristics of its hydrochars are not well understood. Therefore, it is of great significance to study the gasification characteristics of single component hydrochars. In this paper, a typical component of MSW, disposable bamboo chopsticks (DBC), was used as raw material to study the effect of hydrothermal carbonization (HTC) conditions on the structural properties and gasification reaction characteristics of DBC hydrochars. The results showed that HTC improved the energy quality of DBC, the HHV of DBC-230-60 sample was 1.62 times of that of DBC, and H/C and O/C decreased from 1.57 and 0.76 of original sample to 1.00 and 0.33 of DBC-230-60. The results of characterization also demonstrate that the aromatization degree of hydrochar and hydrochar semicoke is higher than that of the DBC original one. The specific surface area of hydrochar is lower than that of DBC original sample, but hydrochar semicoke is higher than that of DBC original sample semicoke. Compared with hydrothermal time, hydrothermal temperature has the more significant effect on the structure and gasification reactivity of hydrochar. Higher hydrothermal temperature increases the aromatization degree of hydrochar and decreases the gasification reactivity of hydrochar. The gasification reactivity of hydrochar is worse than that of DBC original sample, which is mainly because the increase of the degree of semicoke arbulization of hydrochar has a greater negative effect on the gasification reactivity than the abundance of pore structure.
Abstract: A small fixed fluidized bed device (ACE Model C) was used to study the cracking reaction path and coke formation mechanism of model compound decaphthalene over Y molecular sieve catalyst at the reaction temperature of 460−540 ℃. The results show that in the initial stage of decalin cracking, H + attacking C−H bond and C−C bond with tertiary carbon atoms on decalin to form non-classical five-coordinated tertiary positive carbon ions is the most important initiation reaction. Decalin cracking products are mainly propylene, propane, isobutane, isopentane, methylcyclopentane, toluene, dimethyl benzene, etc. The yields of the products on the catalyst from large to small are: non-aromatic hydrocarbons, monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons. The catalytic coke formation mechanism of decalin is carbocation mechanism. With the increase of reaction temperature and molecular sieve acid content, the bilayer hydrogen transfer and dehydrogenation condensation ability are enhanced, and the coke yield and conversion are also increased.
Abstract: A catalytic slurry oil (SO) was treated by moderate pre-hydrotreating, and the structural compositions, the thermal stability, the distillate oil yield, and the coking behavior of SO before and after hydrotreating were analyzed. The carbonization performance as well as the co-carbonization performance of the middle distillate (350−500 ℃) and the high boiling point distillate (500−550 ℃) derived from the hydrogenated SO (HSO) were investigated. The results show that the content of naphthenes and hydrogenated aromatics of HSO increases, while the olefin content decreases, and the olefinic hydrogen content of HSO decreases from 2.71% to 0.97%. Thus, the thermal stability of HSO is fundamentally improved. Additionally, compared with SO, the yields of the middle distillate and the high boiling point distillate of HSO increased by 25.8% and 23.1%, respectively. More importantly, there is no significant coke formation during distillation of HSO. The carbonization experimental results show that the anisotropic textural structure of the coke obtained from the middle distillate derived from HSO is the large flow domain structure, and the coke has the lowest coefficient of thermal expansion (CTE) value of 2.25 × 10−6 ℃−1. The carbonization performance of the high boiling point distillate derived from HSO is poor, while the co-carbonization with the middle distillate significantly improves the carbonization performance of the high boiling point distillate. The anisotropic textural structure of the coke derived from carbonization of combined fraction is the large flow domain structure and the CTE value is less than 2.30 × 10−6 ℃−1, when the mass ratio of aromatic fraction to middle fraction is not higher than 2∶1.
Abstract: In this study, coal tar-based phenolic foam (CPF) was prepared using low-temperature coal tar as raw material to partially replace phenol. The chemical structure, apparent morphology, compressive strength, thermal stability, flame retardancy and thermal insulation properties of CPFs were characterized. The results show that CPFs have similar chemical structures to conventional phenolic foam. Comparing with conventional phenolic foam, the compressive strength of 30%CPF and 40%CPF increases by 18.3% and 55.9%, and the pulverization rate decreases by 22.9% and 50.8%, respectively. The results indicated that toughness was significantly strengthened due to the incorporation of aliphatic structures such as alkylphenols. In addition, the thermal stability of CPFs in the low temperature stage also improves. Although the limited oxygen index of CPFs decreases and thermal conductivity of CPFs increases, they still maintain good flame retardancy and thermal insulation properties. The obtained results prove that low-temperature coal tar can significantly replace phenol to prepare phenolic foam with good performance, which provides a new idea for the high-value utilization of low-temperature coal tar.
Abstract: Zinc-zirconium oxide (ZnZr) was effectively coupled with HZSM-5 zeolite in this report. The effects of SiO2/Al2O3 ratio of HZSM-5 zeolite and Zn/Zr ratio on the performance of CO2 hydrogenation to C5+ isoalkanes over the composite catalyst were investigated, respectively. The results show that ZnZr-4/HZSM-5 prepared by SiO2/Al2O3 = 130 and Zn/Zr = 1∶5 manifests the optimal performance of CO2 hydrogenation to C5+ isoalkanes, with CO2 conversion of 17% and CO selectivity of 25%, as well as the selectivity of C5+ hydrocarbons and isoalkanes in C5+ hydrocarbons up to 60% and 89%. Moreover, ZnZr/HZSM-5 composite catalyst shows excellent stability with time on stream for 120 h without losing activity. A suitable coupling between ZnZr and HZSM-5 zeolite is critical for highly selective synthesis of C5+ isoalkanes by CO2 hydrogenation.
Abstract: The structure of the supports can significantly affect the Fischer-Tropsch catalyst activity and selectivity. The porous structure can improve the mass transfer of reactants, enhance the CO conversion activity and C5+ product selectivity; the high specific surface area is beneficial to disperse the loaded metal, improve the catalyst metal utilization efficiency and catalyst stability. However, it is relatively difficult for supports to obtain high specific surface area and macropore structure characteristics simultaneously. A mesoporous (2.9 nm) -macroporous (63.8 nm) bi-porous silica (BP-SiO2) support with a high specific surface area of 1103.2 m2/g was synthesized by the structure-directed hydrolysis method, and its catalytic performance for Fischer-Tropsch synthesis was investigated. The results showed that compared to the Co/SBA-15 catalyst with equivalent mesopore diameter, the catalyst Co/BP-SiO2 showed CO conversion rate nearly increased by 33.3%, CH4 selectivity reduced by 30.1%, improved C5+ selectivity and stability.
Abstract: Ce-Zr oxide support was hydrothermally synthesized from metal nitrates of cerium and zirconium as the raw materials using citric acid instead of alkali precipitant, and then Cu/Ce-Zr catalyst was prepared by the impregnation method. The support and catalyst samples were characterized by XRD, BET, H2-TPR, XPS techniques, and the effects of different hydrothermal time on the structure, properties and performance in water-gas shift reaction were investigated. The results show that the catalyst activity is mainly related to the Cu specific surface area, reduction temperature of CuO and the number of oxygen vacancies on the catalyst surface. Among them, the Cu/Ce-Zr catalyst with hydrothermal time of 12 h has a large Cu specific surface area, a lower reduction temperature of CuO, and a large number of oxygen vacancies, so it shows a good catalytic activity. When the reaction temperature is 320 ℃, the molar ratio of water to gas (W/M) is 2, and the gas space velocity GHSV=6600 h−1, the CO conversion rate is 96.9%, which is close to the thermodynamic equilibrium value of 97.1%.
Abstract: Ce0.8Cu0.2O2 oxygen carrier has excellent performance in chemical-looping reforming of methane coupled with CO2 reduction technology. Different mass of S-1 molecular sieve was added to Ce0.8Cu0.2O2 oxygen carrier. The physicochemical properties and reactivity of the carrier were characterized by XRD, BET, XPS, SEM, TEM and CH4-TPR & CO2-TPO. The effect of S-1 molecular sieve on the performance of Ce0.8Cu0.2O2 oxygen carrier in chemical-looping reforming of methane coupled with CO2 reduction was systematically investigated. Compared with Ce0.8Cu0.2O2 oxygen carrier alone, the specific surface area of the composite oxygen carrier increased from 15.44 to 73.27 m2/g after adding 0.3 g S-1 molecular sieve. At the same time, its thermal stability and structural stability were greatly improved. The CH4 conversion rate of composite oxygen carrier with 0.3 g S-1 molecular sieve increased from 38.93% to 56.03%, and the CO yield increased from 1.18 to 2.16 mmol/g during CO2 reduction.
Abstract: The Cu-M/ZnO catalysts (M = Zr4+, Al3+ and Mg2+) for dimethyl oxalate (DMO) selective hydrogenation to ethylene glycol (EG) were synthesized by the co-precipitation method. The properties of the as-synthesized catalysts were characterized by N2-physisorption, N2O-titration, XRD, H2-TPR, CO2-TPD, SEM, FT-IR and XPS. It was found that the Cu dispersion could be effectively promoted by the dopants incorporated in the Cu/ZnO catalyst. Particularly, a trace amount of Mg2+ and Al3+ dopants could significantly reinforce the chemical interaction between the Cu and ZnO phases by embedding into the ZnO lattice, while the Cu/ZrO2 interaction could be improved with the introduction of Zr4+. For DMO gas-phase hydrogenation, the EG yield of the Cu/ZnO catalyst increased from 75.0% to 85.0% and 90.0% in the presence of Zr4+ and Al3+ dopants, respectively. Particularly, the EG selectivity of Cu-Mg/ZnO catalyst reached up to 95.0% with DMO completely converted for more than 100 h. The correlation between the catalytic behavior and physicochemical features of the Cu/ZnO based catalysts suggested that the surface Cu+ sites was vital for the catalytic behavior with adequate Cu0 sites. Additionally, the strengthened Cu/oxide interaction favored the outstanding stability of the Cu-Zr/ZnO and Cu-Mg/ZnO catalyst for DMO hydrogenation.
Abstract: A series of Ca-Zr catalysts modified by different transition metals were prepared by the sol-gel method and their catalytic performance in the synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate (PC) by transesterification at low temperature was investigated. The results indicate that the selectivity to DMC of various transition metal-modified Ca-Zr catalysts follows the order of Co-Ca-Zr > Cu-Ca-Zr > Ca-Zr > Fe-Ca-Zr > Ni-Ca-Zr > Zn-Ca-Zr. For the transesterification over the Co-Ca-Zr catalyst, in particular, the conversion of PC reaches 84.3% with a selectivity of 94.5% to DMC after reaction for 2 h under 35 ℃, a methanol/PC molar ratio of 15, and catalyst amount of 4%. Combining with the XRD, FT-IR, XPS and CO2-TPD results, it is revealed that increasing the strength of basic sites can raise the conversion of PC, whereas increasing the density of basic sites leads to a decrease of the selectivity to DMC. As a result, the Co-modified Ca-Zr (Co-Ca-Zr) catalyst, with the lowest density of surface basic sites but the highest fraction of strong basic sites, exhibits a high conversion of PC and a high selectivity to DMC for the transesterification of PC with methanol at a low temperature.
Abstract: CeO2-WO3 catalysts were successfully prepared by in-situ synthesis and used in the denitrification reaction. The best activity of CW-550 catalyst was achieved at a roasting temperature of 550 ℃, and the denitrification activity of CW-550 reached over 90% at 200 ℃. The superior catalytic performance of CW-550 catalyst can be attributed to the large specific surface area, more Ce3+ species, abundant surface acidity and superior redox performance. The increased Ce3+ facilitates the formation of oxygen vacancies and promotes redox performance. The introduction of WO3, into CeO2 can enhance the amounts of Brönsted acid, which contributes to the improvement of the adsorption and activation of ammonia, resulting in the excellent catalytic performance. The NH3-adsorbed species can react with gaseous NO. However, both of NH3-adsorbed and NO-adsorbed sepcies cannot participate in the SCR reaction effectively. Therefore, the SCR reaction of CW catalysts mainly follows the Eley-Rideal mechanism.
Abstract: A series of Cu(x)/Hβ catalysts were prepared by the impregnation method and the effect on the performance of the catalysts for the selective catalytic reduction of NO with NH3 (NH3-SCR) was investigated. Characterization techniques such as XRD, N2 adsorption-desorption, NH3-TPD, NO-TPD, H2-TPR, EDS and XPS were used to investigate the physical and chemical properties of the catalysts and the reason of the decrease of catalyst activity in the presence of SO2. It was shown that the catalyst Cu(3)/Hβ, the Cu loading was 3% and Cu(2)/Hβ, the Cu loading was 2%, exhibited the better catalytic activity when the initial reaction material contained no SO2 and SO2, and t95 was 169 and 225 ℃, respectively. The analysis results of the catalyst before and after the reaction showed that the main reason for the decrease of catalyst activity in the presence of SO2 was that the ammonium sulfur salt which was formed by the reaction of SO2 and NH3 in the low reaction temperature covers the catalyst active center.
Abstract: To improve the oxidative desulfurization performance, the modified SBA-15 (Fe/Zr-SBA-15) with different Fe/Zr molar ratios were synthesized by direct hydrothermal method. The samples were characterized by XRD, N2 adsorption and desorption, TEM and UV-vis. Zr was incorporated into the framework of SBA-15. Apart from little aggregated iron oxides, most of the Fe species were well dispersed in Fe/Zr-SBA-15. The influence of the reaction temperature, amount of oxidant and dosage of catalyst on the conversion of DBT were investigated using Fe/Zr-SBA-15-1.0 as catalyst, H2O2 as oxidant and acetonitrile as extractant. The removal rate of DBT reached 97.1% under the conditions of reaction temperature 50 ℃, O/S molar ratio of 4 and catalyst dosage of 6 g/L. The synergistic effect of Fe and Zr played important role, with Fe3 + acting as the oxidation activity center and Zr4 + as the center of adsorption. In addition, the removal rate of DBT could still reach 91.3% after 4 cycles and Fe/Zr-SBA-15 showed good stability.
Abstract: A series of metal oxide catalysts were prepared by impregnating Cu, Mn, Fe, Ce and Ti on ZSM-5 molecular sieve. The physicochemical properties of the catalysts were characterized by SEM, XRD, N2 adsorption/desorption, XPS, H2-TPR, and the catalytic oxidation of toluene was investigated. The results showed that Cu/ZSM-5 had rough surface, uniform distribution of metal, good pore structure, superior low-temperature reducibility and abundant adsorbed oxygen species. Cu/ZSM-5 with 5% loading exhibited excellent catalytic activity for toluene oxidation and the best sulfur resistance performance, with t90 (GHSV=24000 h−1) being 224 ℃ in SO2 environment. In-situ DRIFTS experiments revealed that the degradation path of toluene was as follows: toluene was first adsorbed on the surface of the catalyst to form adsorbed toluene, then it was converted into benzaldehyde and benzoic acid successively on the catalyst. And small molecule organics such as maleic acid and carboxylic acid were formed through ring opening reaction, and finally was oxidized to CO2 and H2O.
Abstract: La0.5Sr0.5Co0.2Fe0.8O3 (LSCF) perovskite materials were prepared by hard template method with SBA-15 as the template in methanol and ethanol solvents and the electrochemical properties of LSCF were investigated. It is found that LSCF prepared with ethanol solvent has larger specific surface area and more oxygen vacancy concentration, which in turn exhibits higher electrical conductivity and better catalytic activity towards oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR). This is because the LSCF prepared by the ethanol solvent has more Co2 + /Co3 + and Fe2 + /Fe3 + electron pairs, which promotes the electronic conduction of the material. In addition, for HOR, the rate determining step (RDS) is the transfer of adsorbed H to the reaction site, and for ORR, the RDS is the reduction of the adsorbed oxygen atom on LSCF. In addition, the reversible single-component cell (RSCC) composed of LSCF prepared by ethanol solvent shows better performance for discharge and water electrolysis. The maximum power density (Pmax) of the RSCC is 232.9 mW/m2, and the current density at 1.3 V is −398.3 mA/cm2 at 700 ℃.
Abstract: In this paper, two-dimensional B/N co-doped porous carbon sheets (BNCSs) were prepared by one-step carbonization using glycine as carbon source and nitrogen source, boric acid as template and boron source. The boric acid template can be removed by water washing, and the synthesis method is green and environmentally friendly. The short pores in BNCSs shorten the transport distance of potassium ions, and the abundant micropores provide a large number of potassium storage active sites. In addition, the higher B/N doping in BNCSs increases the defect degree of carbon matrix, expands the carbon layer spacing, and is conducive to the adsorption, insertion and de-insertion of potassium ions. The measurement results of potassium ion half cell performance indicate that BNCS800 electrode shows high specific capacity (310 mA·h/g at 0.05 A/g), excellent rate performance (100 mA·h/g at 2 A/g) and good cycle stability (after 1000 cycles at 1 A/g, the capacity retention is 75.9%). This work provides a simple strategy for preparing cathode materials with high capacity and long life.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
