Abstract: High-temperature solid oxide electrolysis of CO2 is an efficient, green and flexible method of CO2 conversion and utilization, which can realize CO2 emission reduction and renewable energy power conversion and storage at the same time. It has great applied prospects in the fields of CO2 resource utilization and manned deep space exploration. And with the increasingly severe greenhouse effect and energy crisis, high-temperature solid oxide electrolysis of CO2 is gradually becoming a research hotspot in the field of international environment and energy. This review analyzes and summarizes the basic principles, key materials, performance degradation, stacks, application fields, efficiency, economy and emission reduction potential of high-temperature solid oxide electrolysis of CO2. Moreover, in view of the current problems and constraints that limit the industrial application of solid oxide electrolysis of CO2, multifaceted suggestions and strategies are put forward. This review aims to attract extensive attention in many fields and departments in China, and to promote industrial application of CO2 electrolysis in solid oxide electrolysis cell.
Abstract: Naphthalene is an important component of high temperature coal tar and its content can reach more than 10%. Catalytic polycondensation of naphthalene is an effective way to prepare mesophase pitch and functional carbon materials. In this work, anhydrous AlCl3 was used as a catalyst for the polymerization of naphthalene under atmospheric pressure below 170 ℃ and the reaction mechanism was then systematically investigated. The results indicate that at 110 ℃, the polymer product is mainly composed of tricyclic compounds and the content of heavy products is only 29.5%. At 150 ℃, four to five peri-condensed aromatic compounds turn to be the main components and the content of medium components remains about 50%. At 170 ℃, there appear a large number of six-ring aromatic cores and the conversion of naphthalene reaches 90.7%. The polymer products exhibit good fluidity and solubility in THF, which can facilitate the high-temperature thermal polycondensation and subsequent graphitization process. With an AlCl3/naphthalene molar ratio of 1/100, the second to seventh order naphthalene oligomers are obtained by the simulation of the short chain oligomerization of naphthalene. In contrast, when the AlCl3/naphthalene molar ratio exceeds 10/100, acetylene and methylnaphthalene are produced by the catalytic pyrolysis of naphthalene. The mechanism of “Oligomerization-Pyrolysis-Aromatization” was then proposed to explain the molecular transformation from naphthalene to pitch, which should be useful for the production of mesophase pitch precursor.
Abstract: Direct methanol fuel cell (DMFC) is a potential commercial fuel cell technology that is presently hindered by the expensive noble metal materials of the anode. Developing a method to obtain a uniformly dispersed metal phosphide catalyst with narrow size distribution is still a challenge. In this work, cobalt oxide was deposited on carbon cloth (CC) through atomic layer deposition (ALD), then cobalt phosphide was obtained after the phosphorization process. By changing the number of ALD-based ozone pulses (ALD-O3) for CC, the nucleation and growth modes of cobalt oxide (ALD-CoOx) on the CC were regulated, and CoPx nanoparticles with small particle size and uniform distribution were obtained. The optimized CoPx-based catalyst with 40 cycles of ALD-O3 treatment (CoPx/40-CC) exhibits excellent activity (153 mA/cm2) toward methanol electrocatalytic oxidation reaction in the alkaline solution, which is higher than the catalyst prepared by impregnation (Imp-CoPx/CC), although the CoPx loading of CoPx/40-CC is lower than that of Imp-CoPx/CC. The results indicate that the enhanced activity benefits from the small particle size and the uniform CoPx distribution, which promote the electron-transfer and mass transport kinetics of the methanol electro-oxidation process.
Abstract: Developing highly active and non-noble-metal electrocatalyst for oxygen evolution reaction (OER) is expected to accomplish efficient water splitting hydrogen production and promote the commercial utilization of hydrogen energy. We in-situ fabricated bimetallic NiC2O4-Co electrocatalyst on nickel foam (NF) by a facile one-step solvothermal method in this work. NiC2O4-Co1 self-supported electrocatalyst presents superb OER performance with a low overpotential of 278 mV at 10 mA/cm2 and a Tafel slope of 65 mV/dec, accompanied by excellent stability in 1 mol/L KOH electrolyte. The superior catalytic activity of bimetallic NiC2O4-Co electrocatalyst is attributed to optimized electronic structure, high specific surface area, rapid interfacial charge transfer and the synergistic effect between Ni sites and Co sites during OER process.
Abstract: In this work, a 3D ordered mesoporous structure MoS2/C composite with few-layered MoS2 was synthesized by liquid phase nanocasting method, using SBA-15 as hard template, sucrose as carbon source and ammonium tetrathiomolybdate (ATTM) as MoS2 precursor. The limiting effect of amorphous carbon makes thin MoS2 slices evenly dispersed, and avoids occurrence of MoS2 agglomeration, resulting in the exposure of a large number of MoS2 edges as active sites. The 3D ordered mesoporous structure of the catalyst provides high specific surface areas and ensures transport channels for material and electron for electrochemical HER. As a result, the composite demonstrates efficient HER activity with an overpotential of 165 mV at current density of 10 mA/cm2, and a Tafel slope of 91.1 mV/dec under acidic conditions. This study provides a basis for constructing 3D HER catalyst with high specific surface area and few-layered MoS2 uniformly dispersed.
Abstract: ZnxCd1−xS solid solution photocatalysts with high photocatalytic activity were prepared by the coprecipitation method at room temperature. The optimum process conditions of ZnxCd1−xS photocatalyst for degradation of landfill leachate (LFL) under simulated light and the hydrogen production rate for decomposition of degraded LFL were investigated, including the effects of Zn atom content, the amount of photocatalyst and illumination time on COD removal efficiency and hydrogen production performance. Results show that ZnxCd1−xS exhibits the highest photocatalytic activity with Zn∶Cd = 1∶1. Moreover, when the concentration of Zn0.5Cd0.5S is 1.0 g/L, and reaction time is 3 h, the COD removal efficiency of LFL can be up to 30.85% at room temperature. At the same time, Zn0.5Cd0.5S was applied to decompose degraded LFL to produce hydrogen. When the input amount of Zn0.5Cd0.5S is 0.6 g/L and illumination time is 3 h, the maximum hydrogen production is 1533 µmol, and the H2 production rate is 8312 µmol/(g·h). The hydrogen production obtained in this process is much higher than that of photocatalytic decomposition of pure water. After three recycles, the hydrogen production can still remain above 83% of the initial hydrogen production.
Abstract: TiO2/GO with different graphene oxide (GO) composite ratios were prepared by hydrothermal method and characterized by SEM, TEM, XRD, UV-vis, XPS, Raman and photocurrent. The results show that both TiO2 and GO/TiO2 crystal are anatase type. Part of GO is reduced to the reduced graphene oxide (RGO), properties of which are closer to that of graphene, when GO is prepared by hydrothermal reaction with butyl titanate. And such transformation is conducive to photoelectron transfer. Compared with pure TiO2, the composite TiO2/GO catalyst has a smaller grain size and a higher ratio of adsorbed oxygen/lattice oxygen, which is beneficial to the oxidation of NO. Moreover, lower band gap enhances the abilities of absorbing visible light and the photoelectron response over TiO2/GO catalyst. Therefore, the catalyst exhibits more excellent photocatalytic performance. The photocatalytic denitration performance of the composites was evaluated under visible light. When the GO composite ratio is 1.5%, the catalyst possesses the optimal photocatalytic denitration performance. When the ratio of ammonia to nitrogen is 1:1, the denitration efficiency can reach as high as 88.6%, which is 30% higher than that of self-made unmodified TiO2 and 40% higher than that of V-Ti-W catalyst. The anti-interference ability is significantly stronger than that of commercial V-Ti-W catalysts. It is concluded, from the mechanism analysis, that the oxidation rate of NO plays a key role in the process of photocatalytic denitration, and the presence of ammonia can accelerate the reduction of NO2.
Abstract: A series of Cu-Ce/SAPO-34 bimetallic zeolite catalysts were prepared by impregnation method. The performance of the different quality Cu/Ce ratios zeolite catalysts for selective catalytic reduction of NO was investigated in a catalyst evaluation device. XRD, SEM, NH3-TPD, XPS, and in-situ DRIFTS were used to characterize and analyze the catalysts. The results show that the modified Cu-Ce/SAPO-34 catalyst has good denitration performance and wide activity temperature window. When the content of Cu and Ce is 4%, the zeolite catalyst has the best denitration efficiency; the denitration efficiency is 80% at 325−500 ℃, and the NO conversion rate is more than 99% at 400−500 ℃. The bimetallic oxide species are highly dispersed on the surface of the catalyst, the crystal structure of SAPO-34 is not affected, and the interaction between the active substance and the support is good. 4Cu-4Ce/SAPO-34 has an appropriate amount of acidic sites, and this mixture has positive effects on the denitrification performance and stability of the catalyst. It follows the E-R mechanism in the NH3-SCR reaction process.
Abstract: In this work, the effects of O2 and SO2 on gaseous As2O3 adsorption over W-Cu/γ-Al2O3 catalyst were investigated through adsorption experiment and density functional theory (DFT) method. Experimental results show that the As2O3 adsorption is facilitated by O2, and intensified with the increasing concentrations of SO2. However, it is slightly weakened with the SO2 concentration of 2.0×10−3. The As2O3 adsorption on W-Cu/γ-Al2O3 surface with adsorbed gas constituents was calculated by DFT simulation to reveal the effect mechanism. The promoting effect of O2 on arsenic adsorption is attributed to the formation of adsorbed oxygen. The pre-adsorbed O atom significantly enhances the adsorption activities of adjacent atoms, and the pre-adsorbed O2 molecule provides the active sites for As2O3 adsorption. When SO2 is introduced, the ${{\rm{SO}}^{{2}-} _{4}}$ and ${\rm{HSO}}^-_{4} $ are formed, which change the potential field of substrate surface, and further enhance the As2O3 adsorption. However, the competitive adsorption between SO2 with As2O3 is strengthened with increasing SO2 concentration, and it is the reason for the decreasing trend of As2O3 adsorption with high concentrations of SO2.
Abstract: Oxidation treated carbon materials for exploiting highly efficient and stable loaded catalysts have been proven to be valid. In this work, the surfaces of carbon aerogels (CA) were functionalized with different oxidizing agents, i.e., H2O2 and HNO3. A series of Ru-supported catalysts on carbon aerogels (CA) with/without functionalized were prepared by the impregnation strategy. The impact of oxidation treatment on the texture features of carbon aerogels, the types and contents of formed surface oxygen-containing functional groups, the metal-support interactions and the Fischer-Tropsch synthesis reaction performances of the catalysts were systematically investigated. Our results showed that Ru/CA catalyst without oxidation treatment displayed the highest initial activity but the poor stability, while the Ru/CA-H2O2 catalyst exhibited excellent activity and C5+ selectivity. The oxidation treatment increased the carbon aerogels defects, thereby broadening the specific surface area. The increased content of oxygen-containing functional groups on the surface enhanced the interaction between the support and Ru nanoparticles and improved the stability of the catalyst. Nevertheless, the excessive oxygen-containing functional groups on the surface decreased the activity and the C5+ selectivity of carbon aerogels-loaded Ru catalysts.
Abstract: Herein, SiO2 supported metallic Ni (Ni/SiO2) and bimetallic Ni-Zn (NixZn/SiO2) (x represents the Ni/Zn atomic ratio) catalysts were prepared by the incipient wetness impregnation method and their activities were tested in vapor phase hydrodeoxygenation (HDO) of anisole under 0.1 MPa. The characterization results show that Ni-Zn alloy forms in NixZn/SiO2 after reduction at 550 °C, and a suitable Ni/Zn atomic ratio (30) leads to smaller alloy particle size and consequently more H2 adsorption amount than others. In the HDO reaction, the formation of Ni-Zn alloy facilitates the direct deoxygenation pathway and suppresses CO methanation and C−C bond hydrogenolysis, which is ascribed to the isolation effect of the Ni atoms by the oxophilic Zn ones. Ni30Zn/SiO2 gives not only higher anisole conversion but also higher selectivity to benzene than Ni/SiO2. Therefore, the introduction of a suitable amount of oxophilic Zn in Ni/SiO2 promotes the HDO of anisole to benzene. Finally, we propose that the Ni30Zn/SiO2 deactivation is related to the oxidation of Ni-Zn alloy and carbon deposition on the catalyst surface.
Abstract: A class of TiO2 modified VPO catalysts were prepared by organic solvent-heating method in the present work. The catalysts were characterized by TEM, XRD, XPS, NH3-TPD and CO2-TPD techniques. The catalytic performances were evaluated in the aldol condensation of acetate acid and formaldehyde to acrylic acid in a fixed-bed reactor. The results show that the addition of TiO2 significantly changes the proportion of V content forming V5+ and V4+ ion pair to total V with the unmodified VPO catalyst. As the precursor of TiO2 is rutile phase and Ti/V molar ratio is 2.0, the proportion of V content forming V5+ and V4+ ion pair to total V reaches the maximum, resulting in the best acrylic acid yield (18.0%) and acrylic acid space-time yield (6.61 mmol/(g·h)). It indicates that for the VPO catalyst modified by TiO2, the redox cycle of V5+ and V4+ ion pair plays a major role in the catalytic reaction of formaldehyde and acetate acid to acrylic acid.
Abstract: Based on the circulating fluidized bed (CFB), Xinjiang Zhundong coal (ZDC) gasification ash (FA: fly ash; BA: bottom slag) was analyzed by industrial analysis, ultimate analysis and Fourier infrared spectroscopy to determine the basic properties and functional group species. The results show that BA contains up to 99.30% in ash, while FA shows high fixed carbon and C content of 69.30% and 73.78% respectively. Furthermore, the carbonaceous forms and surface morphology of ZDC and FA were characterized by Raman, XRPES and SEM, and the pyrolysis, combustion and gasification characteristics of ZDC and FA were studied with TG-DTG methods. XRPES show that C content of the FA surface is 89.42%, and exists primarily as >C–C< and >C–H, while O was in the form of >C=O. Alkaline earth metals Ca bound to the above-mentioned carbon-involved functional groups cause high disorder in FA. SEM observed that the rough and porous FA surface occurs due to spherical particles of molten mineral attached and embedded surface and pore channels. The thermal conversion characteristics show that the maximum weight loss rate peak temperature of pyrolysis and combustion of FA is significantly higher than that of ZDC, indicating that the pyrolysis and combustion performance of FA is reduced. However, 100% carbon conversion of FA uses about half the time compared with ZDC and the gasification performance has improved significantly since it has well-developed pore structures, more amorphous carbon and abundant active sites, enhancing diffusion of CO2 from gasifiers. Briefly, FA has the potential and ability to be recycled for direct utilization in CFB as gasification feed.
Abstract: Amine CO2 capture is an effective post-combustion carbon capture (PCC) technology, while CO2 mineral carbonation is a safe and stable method for CO2 storage. In this paper, these two methods were combined, and the CO2 absorption-mineralization performance of mixed amine solution coupled with CaO under different ratios of mixed amine solution, temperature, reaction time and CaO addition ratio were studied by using MEA/MDEA mixed amine solution as the CO2 absorbent and using CaO as the CO2 mineralizing raw material. The results show that CaO could effectively mineralize the CO2 absorbed in MEA/MDEA solution, realizing the regeneration of MEA/MDEA solution simultaneously under normal temperature and pressure. Meanwhile, the MEA/MDEA solution can still maintain a high CO2 conversion rate (77.4%) and CO2 cycle loading (1.03 mol/L) after five cycles of absorption-mineralization experiments. The FT-IR and XRD analyses reveal that the addition of CaO makes a large amount of Ca2+ and OH- into the MEA/MDEA solution, which could react with CO$_3^{2{\rm{ - }}} $/HCO$_3^{\rm{ - }} $ and protonated amine in the solution to form calcium carbonate precipitate and free amine respectively, thus realizing the mineralization of CO2 and the regeneration of MEA/MDEA solution. The main component of solid products obtained is calcium carbonate, and calcite is its main crystal form.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
