Abstract: Waste gasification has the potential to contribute to China’s transition towards carbon neutrality and zero waste cities via the recirculation of waste as secondary carbon feedstock for the production of chemicals with lower/and or zero carbon footprint, green hydrogen with zero carbon footprint and CO2-neutral synthetic liquid fuels. With China’s significant coal gasification capacity and associated experiences and expertise, Coal-to-X could act as a bridge to Waste-to-X for carbon intensive sectors such as the waste management, chemical production and mobility sectors. To illustrate the opportunities in these areas, this article presented highlights from dynamic global developments in waste gasification, focusing on pioneering industrial developments in Germany between 1980−2000’s as well as current international developments. Lessons learnt from previous and current waste gasification project deployment are shared and enabled the identification of problems which will have to be addressed in the transition from coal gasification towards mono-waste gasification technologies. Additionally, a qualitative evaluation of gasification technologies pointed to the strengths and weaknesses of fixed-bed, fluidized-bed and entrained-flow gasification principles in their application for waste gasification.
Abstract: During the direct coal liquefaction process, coal direct liquefaction residue (CDLR), which accounts for about 30% of the coal input, will be produced and the polycyclic aromatic hydrocarbons can be extracted from it by extraction to prepare high-value carbon materials. The influences of composition and structure of extractants on the extraction rate and properties of extracted products were systematically summarized. The extraction rate of the extractants which have aromatic structure or nitrogen and oxygen atom can reach more than 50%. The extracts in alkane organic solvents mainly contain condensed aromatic structure with 2–4 benzene rings and have a lower molecular weight and heteroatom content. The extracts in heteroatoms containing solvents are mainly composed of condensed aromatic structure with 4–7 benzene rings and have a larger molecular weight. And they are rich in heteroatoms, such as nitrogen, oxygen and sulfur, and have a high atomic ratio of C/H. The extracts of pyridinium-based ionic liquids have higher atomic ratio of C/H and aromaticity. And the ash content of the extracts of ionic liquids containing organic acid ions is close to 0. When coal liquefaction oil or coal tar distillate are used as extractants, the extraction rate can reach 60%, which are suggested for industrial applications of CDLR extraction.
Abstract: Pyrolysis is an effective way for clean and efficient use of coal, as well as an important way for the efficient conversion of waste plastics. Polyvinyl chloride (PVC) and Pingshuo (PS) coal were used in this research object. A two-step treatment scheme was proposed for chlorine-containing plastics that are difficult to be treated harmlessly. The PVC was preheated to remove most of the chlorine, and then the pretreated PVC residue (DPVC) and coal were co-pyrolyzed. GC, simulated distillation, GC-MS, elemental analysis, FT-IR and Raman spectroscopy were used to analyze and characterize the composition and properties of pyrolysis gas, tar and char. The results showed that the co-pyrolysis process of DPVC and PS coal has a synergistic effect, and the co-pyrolysis has an obvious positive synergistic effect on the formation of char and tar. The experimental value of tar yield is higher than theoretical calculation and the maximum increasing value is 3.35%. There is a negative synergistic effect on the formation of pyrolysis water and gas, in which CH4 has the largest decrease in yield, meaning the strongest negative synergy. Co-pyrolysis increases the content of light tar, significantly increases the content of naphthalenes, and reduces the asphalt. When the DPVC addition was 10%, the content of light tar increases by 5 percentage points over the theoretical calculation value. In addition, the co-pyrolysis char surface is smoother, the structure becomes more orderly, and the graphitization degree increases.
Abstract: In order to study the performance of DCLR (direct coal liquefaction residue) modified asphalt mortar, different DCLR modified asphalt mortar with different DCLR contents and filler-asphalt ratios (FA) was prepared. The high-and-low temperature and fatigue performance of asphalt mortar was analyzed by a dynamic shear rheometer and a bending beam rheometer. Using the variance analysis method the influence of the single factor (temperature, DCLR content, FA) and the coupling between these factors on the performance of asphalt mortar was investigated. The results show that the addition of DCLR and filler can significantly improve the high-temperature performance of asphalt mortar, but damage the low-temperature performance and the fatigue performance of asphalt mortar. To comprehensively balance the effects of DCLR content and FA on the performance of the mortar, the DCLR content of 10% and the FA of 1.0 are recommended. Besides, the single factor (temperature, DCLR content, FA) and the coupling between these factors have significant effects on the performance of asphalt mortar, but the effect of the coupling is smaller than that of the single factor.
Abstract: 8 kinds of mixed oil with different feeding time in the same coking cycle were the objects of the study. The optical structure, morphology structure and microcrystalline structure of needle coke formed by mixed oil with different feeding time in coking cycle were quantitatively analyzed by means of polarizing microscope, scanning electron microscope (SEM), XRD and Raman spectroscopy. The results show that the yield of coke after the thermal conversion of the mixed oil is higher than the theoretically calculated yield, indicating that the heavy oil participates in the thermal conversion reaction to form the coke with a streamlined optical structure. In the optical structure of calcined needle coke, MO-8" has the highest fiber content, followed by MO-16", and MO-32" has the lowest fiber content. SEM further proves that MO-8" has more lamellar number and more regular orientation. XRD analysis of needle coke confirms that the microcrystalline structure parameters (interlayer spacing d002, lamellar content N and the number of carbon atoms in each layer n) are very close. However, there are obvious differences in the content of graphite microcrystalline (Ig), and among which MO-8" has the highest content, followed by MO-4", and sample MO-32" has the lowest content. Furthermore Raman spectral analysis certifies that the basic microstructure of needle coke is similar. The fundamental reason is that the refined coal-tar pitch in the mixed oil determines the basic microstructure of needle coke. Due to the continuous circulation of heavy oil in the system, the microstructure of needle coke are different. Hence, the coking cycle is not easy to exceed 32 h in coal-based needle coke production, or else it will seriously affect the microstructure of needle coke.
Abstract: The effects of steaming at varying times and temperatures on ZSM-5 pore structures, framework Al distribution, acid properties and ethanol to propene (ETP) catalytic performance were systematically studied in this study. The results show that the crystallinity and specific surface areas of steam treated ZSM-5 samples decrease with the increase treatment time and temperature. 27Al MAS NMR and Co(Ⅱ) exchange-ICP results show that the isolated framework Al species (Alsingle) can be preferentially removed from the zeolite framework, while the paired Al sites (Alpairs) remain relatively stable after steam treatment. The characterization of Py-IR reveals that the concentration of B acid sites and the acid strength are all declined with the steaming time or temperature increase. The catalytic results of ETP at 450 ℃ show that the sample after steaming gives improved selectivities to propene and butene at the expense of ethene conversion and alkanes selectivity relative to the unmodified zeolite. Besides, a good positive correlation between ethylene conversion and Alsingle concentration is found, whereas the propene formation is influenced by the combination effect of Alsingle and Alpairs sites.
Abstract: The reaction mechanism of the isomerization of glucose to fructose and further dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) in subcritical water was investigated by the dispersion-corrected density functional theory (DFT-D) method with Dmol3 package in Materials Studio. The implicit solvent model was used to evaluate the bulk solvation under the conductor-like screening model (COSMO) approach, in which a dielectric constant ( ε ) of 27 was used to represent the subcritical water at 523.15 K. The explicit solvent model was adopted with a hybrid micro-solvation-continuum approach, to indicate the micro-solvation by explicit H2O molecules and the bulk solvation with ε = 27. The calculation results indicate that explicit H2O molecules participate in the reaction and catalytically promote the proton transfer processes, suggesting that the explicit solvent model is preferable to the implicit solvent model to represent the conversion of 5-HMF in subcritical water. The isomerization of glucose to fructose is exothermic by 5.26 kcal/mol, where the isomerization of open-chain glucose to enol form is the rate-determining step, with the activation energy of 33.89 kcal/mol; the free energy of transition state configuration depends upon both the difficulty in α–H extraction of open-chain glucose and the stability of formed carbocation. In contrast, the hydration of fructose to 5-HMF is exothermic by 12.93 kcal/mol and the first hydration is the rate-determining step, with the activation energy of 50.59 kcal/mol; the free energy of transition state configuration is determined by the stability of carbocation formed by the dehydration of protonated OH group at C(2) site of fructose. This work discloses the promoting effect of Brønsted base on the isomerization of glucose to fructose and that of Brønsted acid on the dehydration of fructose to 5-HMF, which may provide certain clues to the modification of catalytic sites and the selection of solvent in the conversion of glucose to 5-HMF.
Abstract: Highly selective synthesis of liquefied petroleum gas (LPG, ${\rm{C}}_3^0 $ and ${\rm{C}}_4^0 $) from CO2 hydrogenation have realized over the In2O3/SSZ-13 bifunctional catalyst. The physicochemical properties of the bifunctional catalyst were characterized by X-ray diffraction spectroscopy (XRD), N2 physical adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and NH3 temperature-programmed desorption (NH3-TPD). The particle size effect of In2O3 and reaction conditions were investigated for CO2 hydrogenation to LPG over the In2O3/SSZ-13 bifunctional catalyst. Results indicate that CO2 conversion and CO selectivity are related to the particle size of In2O3, and fresh 5 nm In2O3 shows the highest CO2 conversion (11.7%) and the highest CO selectivity (61.0%), since it is more prone to reverse water gas reaction (RWGS). However, the hydrocarbon distribution does not exhibit a dependence of In2O3 size changes, and the selectivity of LPG maintains at 90% and the selectivity of propane reaches up to 76.8% due to the 8-MR micropores and strong acid sites of SSZ-13 zeolite. Additionally, the yield of LPG shows a volcano type with increasing reaction temperature, and the optimal reaction temperature is 370 ℃. Low space velocity is more favorable to the CO2 conversion, and LPG selectivity in hydrocarbon products still maintains about 90%. High reaction pressure is beneficial to improving the yield of LPG via promoting the secondary hydrogenation reaction over the SSZ-13 zeolite and inhibiting CO formation. Furthermore, no obvious deactivation is observed after a time on stream (TOS) of 100 h over the In2O3/SSZ-13 bifunctional catalyst at 350 ℃, 3 MPa and 9000 mL/(gcat·h). The research provides a new strategy for highly selective synthesis of LPG from CO2 hydrogenation.
Abstract: High thermal conductivity supports, core-shell structure SiO2@Al, was successfully prepared by hydrolyzing tetraethyl orthosilicate (TEOS) under weak alkaline condition and using hexadecyl trimethyl ammonium bromide (CTAB) as the template. 15% (mass fraction) of cobalt was loaded on these supports by excessive impregnation method for Fischer-Tropsch synthesis reaction. The prepared catalysts have high metal aluminum content, high specific surface shell layer and relatively uniform pore size of 2.6−2.8 nm. By changing the added amount of TEOS, the content of silica in the supports and the thickness of the shell layer can be adjusted. As the thickness of the silica shell layer increases, the specific surface area of the supports gradually increases, the interaction between cobalt and the supports increases, and at the same time, the reduction degree of the catalysts decreases. The silica shell enhances the dispersion of metallic cobalt and avoids deactivation caused by agglomeration of metallic cobalt on aluminum particles. Under the condition of similar conversion rate, the catalyst 15Co/5-SiO2@Al with a thinner shell layer has the best performance in Fischer-Tropsch synthesis which is mainly due to the moderate metal-support interaction between the thin silica shell layer and metal cobalt particles. The thinner silica shell layer can anchor and disperse cobalt species to increase the reduction degree of cobalt species.
Abstract: Titanium silicalite (TS-1) zeolites with different distribution of Ti species were synthesized through altering different amounts of (NH4)2SO4 as crystallization-mediating agent. The distribution of titanium species of TS-1-X samples (X represents the molar ratio of (NH4)2SO4 to SiO2) was systematically investigated via ICP-AES, FT-IR, UV-Vis, UV-Raman and other techniques. The TS-1-X zeolite samples were applied in the epoxidation of 1-hexene reaction. It was found that the appropriate amount of ammonium salt not only facilitated the enrichment of titanium species from liquid phase to solid phase and promoted the incorporation of Ti into the MFI skeleton, but also resulted in the formation of uniformly small TS-1 crystals due to the inhibition of rapid growth of crystals. However, much more amounts of (NH4)2SO4 led to the formation of extra-framework Ti, including anatase TiO2 and amorphous Ti species. Meanwhile it promoted the rapid growth of grain resulting in larger TS-1 crystals. Ti-rich TS-1 sample synthesized with molar ratio of (NH4)2SO4 to SiO2 of 0.2 exhibited higher conversion of 1-hexene (42 %) and effective utilization of H2O2 (81.8 %). In addition, the effect of ammonium salt’s composition on the properties of TS-1 was investigated by experiments and characterizations. It was found that ammonium salt could regulate the process of crystallization through its own anion and changing PH of the synthesis gel.
Abstract: In this paper, the plasma coupled catalyst was used for the dry reforming of methane (DRM). The impacts of the reaction temperature, the molar ratio of CO2/CH4, and the concentration of the main gas components (N2, H2, CO, H2O) on the conversion rate of CH4 and the energy efficiency of plasma catalysis were observed. The results shows that the conversion rate of CH4 is 41.57%, with La-Ni/γ-Al2O3 as the catalyst, the reaction temperature being 450℃ and the molar ratio of CO2/CH4 being 1.0, and without other gases. The conversion rate of CH4 increases with the increase of the molar ratio of CO2/CH4. The conversion rate of CH4 is 92.82% respectively during DRM by plasma catalysis, with the molar ratio of CO2/CH4 being 5.0. The reaction temperature and the molar ratio of CO2/CH4 have a significant effect on CH4 conversion. The excited particles in the system are influenced by the changes of gas composition, which affect not only CH4 conversion directly, but also the carbon deposition on the surface of catalyst. The addition of N2 and H2O in the reaction system not only improves conversion of CH4 but also inhibits carbon deposition. The addition of H2 and CO reduces the conversion of CH4 significantly. The results are expected to provide basic data and reference for the development of the synthetic process of chemicals through biomass gasification.
Abstract: The isomerization and hydroformylation of butene under the catalysis of Rh-BIPHEPHOS were investigated by varying the butene feed and reaction temperature. The results indicate that in the presence of syngas, with 1-butene as feed, more isomerization product (i.e. 2-butene) is detected in comparison with the hydroformylation products, whereas with 2-butene as the feed, the hydroformylation is superior to isomerization. Due to the equilibrium limit between 1-butene and 2-butene, the increase of temperature shows a great positive effect on the isomerization reaction. Furthermore, under the catalysis of Rh-BIPHEPHOS, more n-pentanal is always formed than i-pentanal, as the larger bite angle of BIPHEPHOS restricts the intermediate rearrangement in the formation of i-pentanal.
Abstract: Two tungsten oxides (WO3-500 and WO3-900) were prepared at different calcination temperatures by using ammonium mettungstate as tungsten source. The physicochemical properties of WO3 before and after Pt loading were systematically characterized by XRD, SEM, TEM, XPS, H2-TPR, and NH3-TPD. The influence of the crystallization degree of WO3 on the hydrogenation of naphthalene was studied under low-temperature reaction conditions. Compared with the WO3-900 support, WO3-500 obtained by calcination at lower temperature exhibited a lower crystallization degree with a large amount of W5+ species, which resulted in strong interactions with Pt. The strong interaction between W species and Pt contributed to the high acidic strength. The Pt/WO3-500 catalyst demonstrated excellent catalytic performance for naphthalene hydrogenation to decalin at low reaction temperature (70 ℃) with full conversion and 100% decalin selectivity. Under identical conditions, conversion and decalin selectivity were only 26.7% and 1.7% over the Pt/WO3-900 catalyst. Combining the characteristics of the catalysts and their catalytic results, we revealed the promoting role of oxygen defects in WO3-supported Pt catalysts in the hydrogenation of naphthalene to decalin, which will provide theoretical guidance for designing efficient WO3-supported Pt catalysts for hydrogenation reactions.
Abstract: Hydroxyapatite (HAP) and a series of Sr-doped HAP supports (Ca9Sr1, Ca8Sr2 and Ca7Sr3) were synthesized by co-precipitation method, and the supported Co3O4 catalysts were prepared by impregnation method. The prepared samples were characterized by XRD, N2-physisorption, Raman, FT-IR, H2-TPR, XPS, O2-TPD and CO2-TPD, and the N2O decomposition performance of the catalysts were studied using a continuous flow microreactor. The experiment results show that the order of catalytic activity is Co/Ca8Sr2 > Co/Ca9Sr1 > Co/HAP > Co/Ca7Sr3. When the Sr/Ca ratios are 1∶9 and 2∶8, the structure of the HAP carrier is better maintained. Sr doping not only promotes the dispersion of Co3O4, but also increases the number of Co2+ and surface oxygen vacancies on the catalysts. Furthermore, an appropriate amount of Sr doping can increase the surface alkali content and basic site density of the catalyst, which is more conducive to N2O activation and O2 desorption.
Abstract: Three-dimensionally interconnected macroporous (3DM) Al2O3 was prepared by phase separation. Macropore size of the obtained Al2O3 is 250 nm with a bimodal pore distribution (at about 21 and 250 nm, respectively) and the BET specific surface area of 174 m2/g, as well as the crushing strength of 16.5 N/mm. Ni and Mo on the 3DM catalyst are uniformly dispersed on the surface of the support. The active phases of sulfurized catalyst possess length of 3−10 nm and stacking layers of 1−7. The stacking distribution of active phase more than 4 layers is about 40%, forming a non-uniform active phase structure. Compared with the industrial catalysts, the hydrodemetallization (HDM) rate, hydrodesulfurization (HDS) rate and hydrodecarbonization (HDCCR) rate of the 3DM catalyst increase by 6.2%, 6.0% and 6.8%, respectively. The pore structure, surface properties, active phase structure and their synergistic effect may be the main reasons for the excellent catalytic performance of the 3DM catalyst.
Abstract: The chemical and mineralogical characteristics of fly ash from a municipal solid waste incineration (MSWI) in China and the influence of processing parameters on heavy metals removal during leaching were investigated in this work. The fly ash particles had complex surface structure with limited specific surface area. The alkali chloride and metal salts in MSWI fly ash showed evidently impact on leaching efficiency. Metal leachability was related to their properties and speciation in fly ash. Water-soluble salts such as KCl, NaCl and CaCl2 in fly ash were easily washed out. In this study, removal efficiency by water washing was achieved to 93.1% for Cl, 41.4% for Na, 48.5% for K and 24.8% for Ca, respectively. Mineralogical analysis also revealed change of fly ash mineral phases and specification distribution after water washing. Under liquid to solid ratio of 40∶1 L/kg and treatment time of 120 min, the leaching process achieved high dropping yields of toxicity characteristic leaching procedure (TCLP) concentrations for Cu, Zn Cd and Pb (80%−100%), moderate dropping yields for As (30%−80%) and relatively low dropping yields of Ni (< 30%). In addition, heavy metals such as Pb and Zn in fly ash with twice water washing treatment at a low liquid-solid ratio could reach lower TCLP concentrations. The result indicated that the combination process of twice water washing and one acid washing could significantly reduce the environmental risk of MSWI fly ash.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
