Perhydro-dibenzyltoluene (18H-DBT) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of its high hydrogen storage, easy transportation, low price and other advantages. The 18HDBT dehydrogenation reaction rate is the key point of the hydrogen storage. In this work, the relationship between the Pt dispersion, the average coordinated number and the total catalyst activity for 18H-DBT dehydrogenation reaction was studied. Al2O3 with the large specific surface area was synthesized by the sol-gel method and Pt/Al2O3 catalysts were prepared by incipient wetness impregnation. Their catalytic performance was tested by 18H-DBT dehydrogenation reaction. It was found that the relationship between the Pt dispersion and the catalytic performance is a volcano curve. The optimal dispersion of Pt for dehydrogenation reaction is 11.16 %. That's because that there exists a balance between the Pt dispersion and the average coordinated number in order to obtain the best total catalyst activity. The experiments and characterization results show that the increasing of Pt dispersion will increase the active site number but the average coordinated number will decrease. DFT calculation results further confirm that the catalytic activity of the single active site would decline with the decreasing average coordinated number.

As the ideal NO removal technology, the biggest challenge associated with the direct catalytic decomposition of NO is the development of highly active deNOx catalysts at low temperatures.

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An excellent high-temperature-resistant scale inhibitor, polyaspartic acid-prolineamide (PASP-Pro), was synthesized by polysuccinimide (PSI) and L-prolineamide (L-Pro), and then characterized by 1H-NMR and FTIR analysis. The inhibition performance of PASP-Pro on CaCO3 precipitation was studied at different temperatures through static tests; at the same time, the influence of PASP-Pro on the crystallization process of CaCO3 was investigated by combining the electrical conductivity test of CaCO3 solution with different CaCO3 scale characterizations. The suitable synthesis and evaluation conditions for PASP-Pro were obtained, and a possible multi-stage scale inhibition mechanism of PASP-Pro for CaCO3 scale was then suggested. PASP-Pro has better thermal stability and high-temperature scale inhibition performance (exceeds 87% after pretreatment at 150 °C) than PASP. In addition, PASP-Pro exhibited a promising anti-scaling property by inhibiting the crystallization of CaCO3; the induction period and the nucleation period of the CaCO3 crystallization process were prolonged nearly four times. It was found from XRD patterns that vaterite, an unstable crystalline phase, gradually emerged with the addition of the scale inhibitors, and the aragonite crystals are clearly observed in SEM images. Finally, the possible multi-stage scale inhibition mechanism of PASP-based inhibitors was proposed, including coating impurities, electrostatic repulsion, and inhibiting dehydration and rearrangement of CaCO3 crystallization.

Hydroxyapatite (HAP) supported Rh, Fe, and Rh-Fe catalysts were prepared by impregnation, and the synergy effects between the catalyst and NTP (non-thermal plasma) on N2O catalytic decomposition were also investigated. CO2-TPD results show that HAP synthesized at high pH have a greater number of surface alkaline sites and promoted the adsorption of N2O. RhFe/HAP-11 catalyst exhibited 95.9

As one of the important atmospheric pollutants, the removal of NO in flue gas at low temperatures is still a severe challenge. Selective catalytic reduction (SCR) with urea is an effective method for NO removal at low temperatures. Herein, through directly loading urea, an Fe-modified Mn-based molecular sieve catalyst with good low-temperature urea-SCR activity was prepared by a stepwise impregnation method. The results show that with a mass ratio of Mn/Fe of 10:0.5 and a calcination temperature of 500 degrees C, the catalyst loaded with 15 wt % urea had the highest catalytic activity of 98.5% at 250 degrees C. Online mass spectrometry results show that NH3 formed from the decomposition of urea reacts with NO when the temperature is above 150 degrees C, while urea directly reacts with NO below 150 degrees C. The density functional theory calculation demonstrates that the doping of Fe weakens the strength of the Mn-O bond in MnO2, which makes NO easier to combine with lattice oxygen to oxidize into NO2, thereby promoting the whole urea-SCR reaction. This work provides an overall perspective and theoretical support for the design of urea-SCR catalysts over a wide temperature range.

Polycyclic aromatic hydrocarbons (PAHs) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of their high hydrogen storage, easy transportation, low price, and other advantages. Dehydrogenation is the key point of the PAH hydrogen storage. However, the dehydrogenation reaction rate of perhydro-PAHs is slow, and their pathway is still not clear. To clarify the PAH dehydrogenation pathway, three kinds of perhydro-PAHs containing six-membered rings (methylcyclohexane, perhydro-diphenylmethane, and perhydro-dibenzyltoluene) are selected, and their dehydrogenation processes over the Pt/Al2O3 catalyst are carried out by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). It was found that the dehydrogenation in the six-membered ring started in the para position of the -CH3 group, and then, the six-membered ring was transformed into a benzene ring gradually. Between the six-membered rings, dehydrogenation started from the side ring, which has fewer groups.

The large-scale utilization mode of renewable energy based on “green electricity+green hydrogen”is an important measure to achieve the carbon neutrality. However, the current hydrogen storage and transportation technology cannot meet the large-scale and cross-temporal needs of this utilization mode.Hydrogen storage by liquid polycyclic aromatic hydrocarbons is considered to be the most likely technology to achieve large-scale safe and efficient off-site hydrogen storage and transportation. This article introduces the basic principle of polycyclic aromatic hydrocarbon liquid organic hydrogen storage technology and the physicochemical properties of common liquid organic hydrogen carriers, analyzes the key parameters of organic hydrogen carriers, explains the intra-ring and inter-ring dehydrogenation reaction mechanism of polycyclic aromatic hydrocarbons from the perspective of steric hindrance, and summarizes the further research progress on the dehydrogenation catalysts from the aspects of active component dispersion, surface charge effect,hydrogen overflow and low coordination number. The technical difficulties such as the high dehydrogenation temperature, low cyclic dehydrogenation rate and high catalyst cost and the future application scenarios and development directions such as the energy optimization and catalyst modification are prospected.

混凝土桥塔的裂缝扩展直接影响桥塔的使用寿命,为了探讨温度场对桥塔既有裂缝宽度的影响,以某双塔悬索桥混凝土桥塔为例,对混凝土桥塔的日照温度场、裂缝宽度和深度进行观测,并建立混凝土桥塔实体三维模型,模拟了桥塔的温度场和裂缝的扩展情况.通过实测值与理论计算值比较分析表明,3个季节塔壁内、外表面温度随时间变化近似均呈正弦曲线变化趋势,塔外日较温差比塔内大;桥塔沿壁厚4个方向的温差变化趋势相近,且桥塔内、外表面最大正、负温差均发生在冬季,最大值分别为20.4℃、-11.5℃.桥塔裂缝随着塔壁厚度方向温差变化有明显的闭合和张开现象,最大幅值约为0.14 mm,但裂缝扩展并不明显,可认为裂缝扩展到一定程度后不再发展.然而桥塔裂缝闭合和张开现象造成裂缝修补困难,常规修补方法效果不是很理想,这与实桥裂缝修补后再次开裂的现象十分吻合.

传统氨选择性催化还原(NH3-SCR)法在大气污染物NO的脱除中得到广泛应用,但仍存在催化剂有毒、操作温度高及氨逃逸等缺点,不能满足日益增多的低温应用场景和更高的环保要求.本文采用浸渍法制备了SBA-15分子筛负载的锰铁双金属催化剂,研究了非热等离子体协同催化剂低温下直接催化还原NO的性能.活性测试结果表明,室温下等离子体输出电压为12kV时,等离子体协同催化的NO转化率达到97.8％.表征结果显示等离子体协同反应前后催化剂的孔道结构和物理形貌未见明显变化.在线质谱分析结果表明,等离子体协同催化作用下,NO被直接分解为N2和O2.由机理分析可知,不同价态Mn物种间的电子传递削弱了催化剂表面吸附态NO分子中N—O键,使得等离子体分解NO的能耗下降.

The carboxylate groups on Pt/Al2O3 catalysts increase the proportion of Pt (1 1 1) and Pt (1 0 0) planes that facilitate H18-DBT dehydrogenation.

The morphologies and the electron property of catalysts play the very important roles in the hydrogenation and dehydrogenation of liquid organic hydrogen carriers (LOHCs) such as dibenzyltoluene (DBT). The different morphologies and pore structures of gamma-Al2O3 and MoxC doped gamma-Al2O3 were synthesized as the supports for Pt catalysts. After analyzing of various characterizations and catalytic testing, it was found that the large surface area and the mesoporous structure of catalysts are beneficial to both DBT hydrogenation and perhydro-dibenzyltoluene (H18-DBT) dehydrogenation. The doping of MoxC promoted the formation of the smaller Pt nanoparticles and increased Pt dispersion. The forming Pt-Mo structure is beneficial to hydrogen spillover which suppress the formation of by-product. The high Pt dispersion of 0.1 wt% MoxC doped Pt/Al2O3 catalyst plays the positive roles in increasing H18-DBT dehydrogenation activity. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

MnO2-based oxide catalysts have recently drawn so much attention owing to its good catalytic activity for NOx direct catalytic decomposition at low-temperature. As the reaction mechanism of NO direct catalytic decomposition on different MnO2 surfaces is not yet clear, it is important to understand the influence of different crystal surfaces of beta-MnO2 on catalytic activity for NO decomposition. The correlation of NO chemisorption with its dissociation pathways on beta-MnO2(1 1 0) and (101) surfaces are investigated based on density functional theory (DFT) with Vienna Ab-initio Simulation Package (VASP). The calculation results have shown that NO prefers to be adsorbed on beta-MnO2(1 1 0) instead of beta-MnO2(1 0 1) surface. The analysis results of density of states and differential charge density indicate that the interaction between NO and beta-MnO2(1 1 0) surface is stronger and the adsorbed NO had more charge transfer with beta-MnO2(1 1 0) surface. The effective activation energies of the possible NO dissociation pathways on the beta-MnO2(1 1 0) and (101) surfaces are 2.57 and 3.07 eV, respectively. The lower energy barrier on beta-MnO2(1 1 0) must be associated with the bridge adsorption of NO and more electrons transfer from NO to the surface, which is conducive to the breaking of N-O bond.

•The correlation of NO chemisorption with its dissociation pathways.•The effective activation energies of the possible NO dissociation pathways.•NO prefers to be adsorbed on β-MnO2(110) instead of (101) surface.

Dibenzyltoluene (DBT) is a promising liquid organic hydrogen carrier (LOHC) with theoretical 6.2 wt % hydrogen storage capacity which can be coupled with a renewable energy power generation system. In this work, the surface hydroxyl groups and surface oxygen vacancies (SOVs) on alumina were modified by a convenient and environmentally friendly plasma treatment method. Different Pt/Al2O3 catalysts were prepared via impregnation of the treated alumina, and the effects of different surface hydroxyl groups and SOVs on their reactivity for the reversible hydrogenation and dehydrogenation of DBT were investigated. The results show that SOVs increased after H-2 plasma treatment, whereas the surface hydroxyl groups increased and SOVs decreased after O-2 plasma treatment. Both the surface hydroxyl group and SOV can improve Pt metal dispersion. The more interesting observation is that the hydroxyl groups promote hydrogen spillover and the proportion of Pt(0), which not only benefit the catalyst hydrogenation and dehydrogenation activity but also reduce side reactions and increase long-term cycle performance. However, increased SOVs increased the fraction of low coordinated Pt which reduces the long-term cycle performance of the catalyst. As a result, increasing surface hydroxyl groups and appropriately reducing SOVs on Pt/Al2O3 are propitious for improving both reactivity and long-term cycle performance when using DBT as a LOHC.

As a material with high hydrogen storage density, ammonia borane has attracted the attention of researchers. Ammonia borane can release hydrogen gas through hydrolytic dehydrogenation and pyrolysis dehydrogenation, where hydrolytic dehydrogenation has a low actual hydrogen storage density and is expensive, which is not conducive to practical application. Direct thermal dehydrogenation research shows that improving the dehydrogenation performance of ammonia borane by metal substitution can not only increase the dehydrogenation rate, but also suppress the generation of impurity gases. In this paper, the density functional theory (DFT) is used to calculate the structural parameters, density of states, and HOMO-LUMO energy difference to obtain the dehydrogenation stability of ammonia borane and alkali metal substituted ammonia borane. Subsequently, the reaction energy barriers of the N-H ... H-B path and the M-H ... H-N path are calculated to obtain which dehydrogenation path is easy to occur. The results show that alkali metal substituted ammonia borane MAB(M = Li, Na, K) is easier to dehydrogenate than AB, and MAB is more likely to dehydrogenate by forming M-H ... H-N double hydrogen bonds. Density functional theory calculations can obtain the structural parameters and related thermodynamic information of each stagnation point on the dehydrogenation reaction path, which provides theoretical guidance for the research and improvement of the dehydrogenation performance of ammonia borane.

Due to the increasing consumption of traditional fossil energy sources and the resulting environmental problems, the need for new energy sources is increasing.Hydrogen is an efficient and clean energy, and developing a suitable hydrogen storage medium is the key to the use of hydrogen energy.Ammonia borane has attracted much attention due to its high hydrogen storage density (19.6 wt %) and room temperature stability.It can be dehydrogenated by hydrolysis and pyrolysis.At present, the pyrolytic dehydrogenation mechanism of ammonia borane is still unclear.In this work, the dehydrogenation of ammonia borane (AB), ammonia borane dimer ((AB)2), and the diaminodiborane (DADB) have been studied based on density functional theory (DFT).The results show that the energy barriers of the first and second steps for AB pyrolytic dehydrogenation are 38.58kcal/mol and 78.14 kcal/mol.(AB)2 dehydrogenation were generated by forming N-H...H-B bond, the energy barriers for the first step (46.45 kcal/mol) is higher than AB.In addition, the energy barrier (21.67 kcal/mol) of DADB to form N-H...H-B bond dehydrogenation is much smaller than (AB)2.It reveals that DADB is easier to dehydrogenate than AB and (AB)2.The above results would provide theoretical guidance for the pyrolytic dehydrogenation of ammonia borane.

采用水热合成法制备了正八面体Cu2O/Cu修饰的多孔Ni(NF)自支撑电极(Cu2O/Cu-NF),并对其进行了形貌和结构表征.在三电极体系下,在碱性介质中以循环伏安法和恒电位安培法测试其对葡萄糖催化氧化性能.结果表明,150℃水热法制备的自支撑电极对葡萄糖的电催化氧化活性最强.响应电流与葡萄糖浓度在3.7×10-3～1.1 mmol/L和1.4～5.0 mmol/L范围内呈线性相关,响应灵敏度分别是6929和706.1μA/(mmol·L-1·cm2),且具有良好的选择性和稳定性,对无酶葡萄糖传感器的发展有重要意义.

分析了气井结盐的原因,即主要是温度和压力降低导致了排出液中盐的过饱和现象.介绍了4种气井除盐防盐方法,包括掺水除盐、热洗除盐、化学防盐和毛细管掺水加抑制剂结盐.就化学除盐防盐中有应用前景的抑制剂进行了重点介绍,亚铁氰化物、表面活性剂、酒石酸盐、氮川三乙酰胺(NTA)抑制剂、复合抑盐剂及降滤缓释抑盐剂均对氯化钠结晶有着很好的抑制效果,抑制机理主要基于改变外界条件提高溶液的过饱和度,或是通过盐晶畸变抑制晶核生成和晶体生长.

Nitrous oxide (N2O) is a common greenhouse gas and urgent need to be contained. Direct catalytic decomposition of N2O by high activity catalyst into N2 and O2 is a low-cost and harmless method. Bimetallic catalysts show good catalytic activity in many classes of reactions, and plasma technologies, applied to prepare of catalyst, are considered to be a promising method. In our contribution, DBD cold plasma is applied to synthesize Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition. The influence of cobalt and rhodium content on N2O decomposition activity shows that the optimal amount of metal is determined as 5wt. % cobalt and 0.5wt. % rhodium loaded on Al2O3. The best working voltage is determined as 18kV. The results indicated that the Rh/Al2O3 catalysts prepared by atmospheric-pressure DBD cold plasma showed smaller size and high dispersion of Rh particles, so that the metal-support interaction and the catalytic activity are enhanced. Atmospheric-pressure DBD cold plasma is proved to be an environmentally friendly and efficient method for preparing high performance Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition.