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221. Coupling of LaFeO3–Plasma Catalysis and Cu+/Cu0Electrocatalysis for Direct Ammonia Synthesis from Air

Author

Cui, Yi, Yang, Hui, Dai, Chengyi, Ren, Pengju, Song, Chunshan, and Ma, Xiaoxun

Abstract

Ammonia (NH3) is an essential commodity manufactured by the chemical industry. However, it is still mainly synthesized via the traditional Haber–Bosch process, which is energy consuming and produces large amounts of CO2. As one of the most promising alternatives, the electrochemical reduction of nitrogen (N2) under mild reaction conditions exhibits only low efficiency for NH3synthesis because of the low water solubility of N2and the high energy of the triple bond in molecular N2. Here, we use an N2fixation strategy of “oxidation–reduction” based on a coupled plasma catalysis and electrocatalytic system. First, a perovskite LaFeO3catalyst is used in a nonthermal plasma to oxidize N2to nitrate/nitrite (NOx–), which quickly dissolves in water for activation in the next step. The theoretical calculations indicate that the LaFeO3with rich surface-reactive oxygen species has better activity and stability in the reaction than poor surface-reactive oxygen species, thereby enhancing the increase of NOx–production. Then NOx–is electrochemically reduced to NH3using a Cu+/Cu0catalyst with considerable activity (3.0 mg h–1cm–2) and high faradaic efficiency (83.2%). The process only requires air and water as reactants. This strategy could provide a new and efficient pathway for NH3synthesis directly from the air.

Published
2022
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222. Novel axial substituted subphthalocyanine sensitized titanium dioxide H12SubPcB‐OPh2OH/TiO2 photocatalyst: Synthesis, density functional theory calculation, and photocatalytic properties.

Author

Yang, Lin, Zhang, Bingbing, Li, Zhuo, Wang, Chen, Jiao, Linyu, Wang, Bing, Wang, Yafei, Ma, Haixia, and Ma, Xiaoxun

Subjects
METAL phthalocyanines, METHYLENE blue, DENSITY functional theory, TIME-dependent density functional theory, TITANIUM dioxide, PHOTOCATALYSTS, WATER purification
Abstract

Utilizing subphthalocyanine (SubPc) and 4,4′‐dihydroxybiphenyl (C12H10O2) as the raw materials, an innovative axial substituted SubPc H12SubPcB‐OPh2OH was synthesized by solvothermal method. The density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) calculations were employed to further study the properties and structures of H12SubPcB‐OPh2OH. To expand photocatalytic activities for organic dyes degradation, H12SubPcB‐OPh2OH was decorated onto surface of TiO2 nanoparticles to fabricate high‐efficiency H12SubPcB‐OPh2OH/TiO2 photosensitive catalysts. The degradation experiments indicated that the H12SubPcB‐OPh2OH/TiO2 catalyst with the mass ratio of 1:25 had the greatest performance in the elimination of methyl orange (MO), bromophenol blue (BB), methylene blue (MB), and acid fuchsin (AF). The 29.4%, 72.5%, 27.6%, and 64.8% of MO, BB, MB, and AF was removed by pure TiO2 in 180‐min, respectively. Under the same conditions, the photocatalytic rate of H12SubPcB‐OPh2OH/TiO2 can reach 96.3%, 99.5%, 97.5%, and 99.5%, separately. The efficiency of the as‐synthesized composite was 3.3, 1.4, 3.5, and 1.5 times higher than that over bare TiO2 for MO, BB, MB, and AF degradation under visible‐light irradiation, respectively. Besides, after five cycles of experiments, the degradation rate of H12SubPcB‐OPh2OH/TiO2 photocatalyst to BB can still reach 90.2%, which demonstrated that the obtained photocatalysts possessed remarkable stability and is much higher than 15.6% of pure TiO2. This study provides a new idea to the construction of photosensitive catalysts based on TiO2 for water purification. [ABSTRACT FROM AUTHOR]

Published
2021
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223. Controlled direct synthesis of single- to multiple-layer MWW zeolite.

Author

Chen, Jie-Qiong, Li, Yu-Zhao, Hao, Qing-Qing, Chen, Huiyong, Liu, Zhao-Tie, Dai, Chengyi, Zhang, Jianbo, Ma, Xiaoxun, and Liu, Zhong-Wen

Subjects
RATE of nucleation, UNIT cell, NANOSTRUCTURED materials, SILANE, ALKYLATION, NANOCRYSTALS, ZEOLITES
Abstract

The minimized diffusion limitation and completely exposed strong acid sites of the ultrathin zeolites make it an industrially important catalyst especially for converting bulky molecules. However, the structure-controlled and large-scale synthesis of the material is still a challenge. In this work, the direct synthesis of the single-layer MWW zeolite was demonstrated by using hexamethyleneimine and amphiphilic organosilane as structure-directing agents. Characterization results confirmed the formation of the single-layer MWW zeolite with high crystallinity and excellent thermal/hydrothermal stability. The formation mechanism was rigorously revealed as the balanced rates between the nucleation/growth of the MWW nanocrystals and the incorporation of the organosilane into the MWW unit cell, which is further supported by the formation of MWW nanosheets with tunable thickness via simply changing synthesis conditions. The commercially available reagents, well-controlled structure and the high catalytic stability for the alkylation of benzene with 1-dodecene make it an industrially important catalyst. [ABSTRACT FROM AUTHOR]

Published
2021
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239. Development of a new continuous process for the production of 3,5-dimethylpiperidine

Author

Lin, Tao and Ma, Xiaoxun

Abstract

The trickle bed reactor (TBR) is more efficiency than the kettle reactor (KR) in the hydrogenation of 3,5-dimethylpyridine (DPY) to 3,5-dimethylpiperidine (DPI) using the same Ru/C catalyst, which has the advantages of higher conversion, stable catalyst performance, milder reaction conditions and large-scale DPY hydrogenation capacity. So the TBR has a good industrial application prospect.

Published
2022
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243. Density Functional Theory Analysis of Chromium Doped on Fe(00ī) Plane Five Typical Corrosive Particles

Author

Tiantian Wang, Zheng Maosheng, Chaoming Wang, Jun Hu, and Ma Xiaoxun

Subjects
Bond length, education.field_of_study, Materials science, Molecular geometry, Atom, Population, Density of states, Analytical chemistry, Density functional theory, Electronic structure, education, Ion
Abstract

The corrosive effects of five typical particles, namely Cl-, OH-, NO3 -, SO4 2- and H3O+, were investigated by using the Density Functional Theory (DFT). Based on theoretical calculations, the Fe(00ī) Cr plane was implemented with corrosive particles to examine their interaction comparing with fresh Fe(00ī) plane. The changes of bond length, bond angle, population, transferring electrons, as well as the contribution of the density of states (DOS) were studied and interpreted. Through interactive analysis of the electronic structures and typical properties, it was revealed that all five types of particles have strong and corrosive capacity on the plane and the erosive abilities of variety of interactions follow the decreasing order of H3O+ > SO4 2- > NO3 - >OH- > Cl-. Furthermore, under the circumstance of H3O+, average bond length of marginal Fe-Fe on Fe(00ī) Cr facet was shorter than that on Fe(00ī) facet, which manifested that the Cr atom is of anti-corrosive property. In addition, the erosive ions have a certain effect on the substrate Fe surface, homologously, essentially doping of Cr atom on Fe(00ī) plane has varying degrees of influences on the electronic structure and orbital overlapping of varieties of corrosive ions.

Published
2017
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246. Preparation of biomass-derived porous carbon supported Ni nanoparticles for CO2 reforming of CH4.

Author

Lv, Penggang, Liu, Dawei, Tian, Bin, Ma, Xiaoxun, Fan, Maohong, and Xu, Long

Subjects
STEAM reforming, ALKALINE earth metals, COKE (Coal product), CHAR, NANOPARTICLES, CATALYSTS, GREENHOUSE gases
Abstract

Dry reforming of methane (DRM) can not only convert and utilize both CH4 and CO2 greenhouse gases, but also produce an ideal chemical feedstock (syngas). Nevertheless, a significant challenge is the development of a low cost as well as highly active and stable catalyst for this transformation process. Herein, we report a Ni/bio-char catalyst integrating the advantages of biomass-derived carbon supports and non-noble metals using a simple impregnation method. The bio-char supports are derived from waste walnut shells, which possess a well-developed porous structure, abundant functional groups, and an appreciable amount of alkaline earth metals, such as Ca and Mg. Compared to the Ni/CC catalyst (Ni supported on coal-derived coke), the as-prepared 10Ni/bio-char catalyst exhibits superior activity and significantly enhanced stability, achieving 90.7% CH4 conversion and 97.6% CO2 conversion at 800 °C. Furthermore, a simple reaction mechanism for DRM over the Ni/bio-char catalyst was proposed based on experimental results and literature studies. [ABSTRACT FROM AUTHOR]

Published
2020
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247. 1H NMR and 13C NMR characterization of n-heptane extraction of low-temperature coal tar reacted with formaldehyde.

Author

Yao, Qiuxiang, Kong, Xiangxi, Dai, Xiaomin, Gao, Junwen, Wang, Rucheng, Zhang, Yujuan, Sun, Ming, and Ma, Xiaoxun

Subjects
COAL tar, FORMALDEHYDE
Abstract

The optimum conditions of toluene insoluble-quinoline soluble fraction (TI-QS) obtained by n-heptane Soxhlet extraction residue of low-temperature coal tar (H-CT) reacted with formaldehyde were determined. And 1H NMR and 13C NMR were employed to analyze the structure of H-CT and its reaction products (P-H-CT). The results show that the yield of TI-QS is the largest at the reaction conditions as follows: reaction temperature 90°C, reaction time 3 h and with 3 wt% addition of catalyst. The contents of aliphatic carbon and aromatic carbon bonded to oxygen are higher in H-CT. The contents of aliphatic CH3 carbon and aromatic CH3 carbon are higher in P-H-CT. The content of methylene decreases and the content of methane increases, but the decrease of methylene is larger than the increase of methane; therefore, CH/CH2 carbon decreases slightly. The content of Hγ is 0.10 wt%, and the contents of Hα and Hβ are all 0.25 wt% in P-H-CT. The Hγ, Hα and Hβ ratios of P-H-CT to H-CT are small, displaying a lower branched degree of P-H-CT. [ABSTRACT FROM AUTHOR]

Published
2020
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248. Catalytic Performance of In/HZSM‐5 for Coupling Propane with CO2 to Propylene.

Author

Tian, Haifeng, Liao, Jiankang, Zha, Fei, Guo, Xiaojun, Tang, Xiaohua, Chang, Yue, and Ma, Xiaoxun

Subjects
PROPANE, OXIDATIVE dehydrogenation, ENDOTHERMIC reactions, PROPENE, EXOTHERMIC reactions, DEHYDROGENATION, ALKENES, INDIUM
Abstract

The dehydrogenation of propane to propylene is endothermic reaction will generate hydrogen, while the hydrogenation of CO2 to light olefins is exothermic reaction with hydrogen as reactant. Using the CO2 hydrogenation reaction to consume the hydrogen from the propane dehydrogenation reaction, which is more beneficial to propylene generation. Thus, a promising approach of coupling propane with CO2 to produce propylene was proposed. A simple wetness impregnation method was used to prepare the In/HZSM‐5 composite catalyst for this coupling reaction. It was characterized by means of XRD, SEM, TEM, H2‐TPR, NH3‐TPD, XPS, TG, and N2 isothermal adsorption‐desorption. Effects of indium loading, feed volume ratio of propane to CO2, reaction pressure and temperature on the coupling of propane with CO2 to propylene were investigated in a fixed‐bed reactor. When the mass content of indium is 12%, the feeding volume ratio of propane to CO2 is 1 : 4, the reaction pressure is 0.3 MPa and the reaction temperature is 580 °C, the propylene selectivity is 71.41%, as well as the conversion per pass of propane and CO2 is 17.74% and 5.08%, respectively. [ABSTRACT FROM AUTHOR]

Published
2020
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