有机硫水解催化剂研究进展

有机硫是焦炉煤气、天然气、黄磷尾气、合成氨等气体净化的重点和难点,其中羰基硫(COS)和CS₂占主要部分。催化水解法被认为是净化工业气体中有机硫的有效途径之一,是一种低成本高效净化技术,能够在较低温度下将COS和CS₂催化水解为H₂S,进而对H₂S进行高效脱除。催化水解法应用于工业精脱硫中具有两大优势:(1)转化率高,反应温度低,不消耗氢源;(2)水解产物H₂S的净化工艺成熟,可进行硫资源的回收。催化水解法已有较成熟的研究和工业应用,然而水解过程中的氧化反应是导致水解剂效率降低和寿命缩短的重要原因。因此,开发出廉价高效的水解催化剂成为本领域的研究热点,H₂S的高选择性是有机硫催化水解的重要指标。以γ-Al₂O₃、活性炭作为载体制备的水解催化剂是目前应用效果较好的催化剂,且γ-Al₂O₃的应用最早、最广泛,但其抗氧能力较差、催化剂易中毒等特点使其在应用过程中受到一定限制。...     

贵金属催化剂低温催化氧化一氧化碳研究进展

随着“双碳”政策的不断推行以及人们环保意识的不断提高,一氧化碳(CO)作为典型的大气污染物,已成为工业废气和汽车尾气排放的主要控制对象。贵金属型CO氧化催化剂具有优异的低温活性、抗中毒抗性能,是CO催化氧化处理的最为有效的手段之一。基于贵金属型CO氧化催化剂的研究现状,重点围绕Pt、Pd、Au、Ag、Rh贵金属催化剂的贵金属调控技术和载体可控技术进行综述,总结了贵金属型CO氧化催化剂的性能优化策略和发展方向,为开发高性能的CO氧化催化剂提供指导。     

镍基催化剂催化氨硼烷水解产氢研究进展

氢气作为一种清洁能源,被认为是化石能源最理想的替代者。安全、高效且稳定的储氢材料的开发是当前氢能源应用研究中面临的最大挑战之一。氨硼烷(NH₃BH₃,AB)因其较高的储氢密度(146 g·L^-1,质量分数为19.6%)、安全无毒及高化学稳定性等特性成为一种重要的化学固态储氢材料。氨硼烷水解制氢反应条件温和,但需要在合适的催化剂存在的条件下进行。通过调节催化剂的活性组分、颗粒尺寸、活性组分的分散度、电子结构等,可显著提高氨硼烷水解产氢速率。综述了近年来氨硼烷水解制氢反应中镍基催化剂的研究进展,重点概述了镍单质、镍化合物以及镍合金催化剂在氨硼烷水解产氢中的应用,阐述了氨硼烷水解产氢反应机理,展望了氨硼烷水解产氢的发展趋势以及面临的挑战。     

非贵金属催化剂催化硼氢化钠水解制氢的研究进展

硼氢化钠水解制氢具有安全方便、放氢温度适中、反应易于控制和制氢纯度高等优点,现已成为制氢技术中的研究热点.但纯硼氢化钠水解放氢速率缓慢、产氢率低,常需添加合适的催化剂以改善硼氢化钠水解的放氢速率.金属催化剂因其具有高的催化活性已被广泛研究.其中,贵金属由于价格昂贵限制了它们的使用,而非贵金属价格低且储量高.并且,近年来有研究发现某些非贵金属催化剂的催化活性有了显著提高.因此,从经济角度出发考虑,将非贵金属用于催化硼氢化钠水解制氢是非常可取的.本文结合近几年国内外非贵金属催化剂催化硼氢化钠水解的发展现状,介绍了非负载型催化剂和负载型催化剂的研究进展,并对其未来的发展趋势进行了展望.     

高纯羰基硫的生产

详细介绍了高纯羰基硫的合成与纯化     

Mn-Fe/ACF催化剂低温选择性催化还原NO

以自制的芳纶滤料基活性炭纤维(ACF)为载体,采用等体积浸渍法制备了一系列1.2%Mn-Fe/ACF催化剂,并将其应用于低温SCR脱硝。采用BET、XRD、FESEM及EDS对催化剂的微观结构进行表征。活性实验结果表明,适量Fe元素的加入有利于提高催化剂的活性,其中1.2%Mn(0.75)-Fe/ACF催化剂在空速高达56 000 h-1、温度为200℃的条件下的脱硝效率可达92%。BET、XRD和SEM结果显示高的比表面积和载体表面金属氧化物的均匀分布有利于提升催化剂的催化活性。     

AGC公司100DID对羰基硫的分析应用

对于羰基硫的分析,使用AGC公司100DID色谱仪来分析COS中H_2、O_2/Ar、N_2、CH_4、CO、CO_2等杂质。     

羰基硫的生产制备和纯化技术发展

羰基硫作为一种重要的一碳化合物,由于其毒性适中、易于降解和对环境相对友好等特点,因此在农药生产制备和熏蒸剂中应用广泛。综述了目前羰基硫的制备技术、纯化工艺及设备,最后对其现有应用及前景进行了简述。     

低温燃料电池阳极催化剂的研究进展

阳极催化剂是低温燃料电池的关键材料之一,研制新型催化剂对燃料电池的性能及成本起着关键作用。从改变催化剂的组成、分散度及调控催化剂的表面结构3个方面综述了近年来低温燃料电池阳极催化剂的研究进展,并展望了该领域今后的发展方向。     

A Noise Thermometer for Practical Thermometry at Low Temperatures

The application of a magnetic-field-fluctuation thermometer (MFFT) is described for practical thermometry in the low-temperature range. The MFFT inductively measures the magnetic noise generated by Johnson noise currents in a metallic temperature sensor. The temperature of the sensor is deduced from its thermal magnetic noise spectrum by applying the Nyquist theorem, making the thermometer in principle linear over a wide range of temperatures. In this setup, a niobium-based dc SQUID gradiometer detects the magnetic field fluctuations. The gradiometer design optimizes the inductive coupling to the metallic temperature sensor, yet equally ensures sufficient insensitivity to external magnetic interference. In order to obtain a highly sensitive and fast thermometer, the SQUID chip is placed directly onto the surface of the temperature sensor. The compact setup of the gradiometer/temperature sensor unit ensures good conditions for thermal equilibration of the sensor with the temperature to be measured, a factor that becomes increasingly important in the temperature range below 1 K. The first direct comparison measurements of the MFFT with a high-accuracy realization of the Provisional Low Temperature Scale of 2000 (PLTS-2000) are presented. Special emphasis is given to the investigation of the linearity, speed, and accuracy of the MFFT.     

Solubility of Fullerene C60 and C70 in Toluene, o-Xylene and Carbon Disulfide at Various Temperatures

The solubilities of fullerene C₆₀ and C₇₀ in toluene, o-xylene and carbon disulfide between the melting point and boiling point of the solvents, respectively, have been measured. The temperature dependent solubility of C₆₀ displays anomalous behaviors. A solubility maximum of C₆₀ around 0 °C for toluene and carbon sulfide and around 30 °C for o-xylene was observed. The temperature-dependent solubility of C₇₀ behaves normally for all the three solvents studied.     

Simultaneous Measurement of Torsional Oscillation and Ultrasound Propagation in Solid 4He at Low Temperatures

Preliminary results of simultaneous measurements of 10 MHz longitudinal ultrasound propagation in solid ⁴He loaded onto torsional oscillator (TO) are reported. Temperature dependence of sound velocity and attenuation and that of amplitude and frequency of TO are measured. The properties of dislocation lines present in the solid samples are extracted from the ultrasound data and are compared with the shifts in TO frequency below 100 mK.     

A New Device for Studying Low or Zero Frequency Mechanical Motion at Very Low Temperatures

We have developed a new ??floppy wire?? device for studying the motion through quantum fluids and solids at very low temperatures. The device is particularly well suited for producing large amplitudes of motion, for measuring drag forces at low frequency, and for studying ??zero?? frequency dynamics by measuring transient behavior. The device is very versatile and allows motion to be studied over a broad range of velocities and amplitudes. It generates negligible heat leaks and so is ideally suited for ultra low temperature experiments. The device has many potential applications in quantum fluids and solids research, including the study of drag forces at low frequencies in both the laminar and turbulent flow regimes, and the investigation of motion in (super)solid ⁴He. We discuss the principles and modes of operation of the device and present some preliminary measurements in vacuum, in normal liquid ³He and in superfluid ⁴He. We also present measurements of a ??floppy grid?? device, which could be used for generating large volumes of quantum turbulence in superfluids at low temperatures.     

Cryogenic Processing: A Study of Materials at Low Temperatures

Cryogenics is an exciting, important and inexpensive technique that already has led to main discoveries and holds much future assurance. Cryogenic processing is the treatment of the materials at very low temperature around 77 K. This technique has been proven to be efficient in improving the physical and mechanical properties of the materials such as metals, alloys, plastics and composites. It improves the wear, abrasion, erosion and corrosion resistivity, durability and stabilizes the strength characteristics of various materials. Cryogenic refines and stabilizes the crystal lattice structure and distribute carbon particles throughout the material resulting a stronger and hence more durable material. In present paper, we have reviewed the effect of cryogenic treatment on some metals, alloys, plastics and composites.     

Growth of Single‐Walled Carbon Nanotubes with Different Chirality on Same Solid Cobalt Catalysts at Low Temperature

Currently, designing solid catalysts at high temperature is the main strategy to realize single‐walled carbon nanotubes (SWNTs) with specific chirality, meaning it is very hard and challenging to create new catalysts or faces to fit new chirality. However, low temperatures make most catalysts solid, and developing solid catalysts at low temperature is desired to realize chirality control of SWNTs. A rational approach to grow SWNTs array with different chiralities on same solid Co catalysts at low temperature (650 °C) is herein put forward. Using solid Co catalysts, near‐armchair (10, 9) tubes horizontal array with ≈75% selectivity and (12, 6) tubes array with ≈82% are realized by adopting a small amount of ethanol and large amount of CO respectively. (10, 9) tubes are enriched for thermodynamic stability and (12, 6) tubes for kinetics growth rate. Both kinds of tubes show a similar symmetry to the Co (1 1 1) face with threefold symmetry for the symmetry matching nucleation mechanism proposed earlier. This method provides a new strategy to study the nucleation mechanism and more possibilities for preparing new solid catalysts to control the structure of SWNTs.     

Raman Studies of Vanadates at Low Temperatures and High Pressures

The spin and orbital ordering have been examined for high-quality SmVO₃ polycrystalline compound using Raman spectroscopy. Measurements were obtained on individual microcrystallites in the approximate y(zz)y and y(xx)y scattering configurations at low temperatures (down to 20 K) and high pressures (up to 2.75 GPa). At room temperature and ambient pressure only the A_g phonons have been observed in both polarizations examined. The decrease of temperature leads to the appearance of extra peaks in the Raman spectra related to the magnetic and structural transitions that occur in the system. We present evidence of a coexistence of the monoclinic and orthorhombic phases accompanied with the coexistence of the G- and C-type OO phases for temperatures below 100 K. However, no sign of any structural transition has been observed in the high pressure Raman spectra (1.87<P<2.75 GPa) at low temperatures T≥80 K, indicating that SmVO₃ remains orthorhombic, at least down to 80 K.     

A Critical Review on Enhancement of Photocatalytic Hydrogen Production by Molybdenum Disulfide: From Growth to Interfacial Activities

Ultrathin 2D molybdenum disulfide (MoS₂), which is the flagship of 2D transition‐metal dichalcogenide nanomaterials, has drawn much attention in the last few years. 2D MoS₂ has been banked as an alternative to platinum for highly active hydrogen evolution reaction because of its low cost, high surface‐to‐volume ratio, and abundant active sites. However, when MoS₂ is used directly as a photocatalyst, contrary to public expectation, it still performs poorly due to lateral size, high recombination ratio of excitons, and low optical cross section. Besides, simply compositing MoS₂ as a cocatalyst with other semiconductors cannot satisfy the practical application, which stimulates the pursual of a comprehensive insight into recent advances in synthesis, properties, and enhanced hydrogen production of MoS₂. Therefore, in this Review, emphasis is given to synthetic methods, phase transitions, tunable optical properties, and interfacial engineering of 2D MoS₂. Abundant ways of band edge tuning, structural modification, and phase transition are addressed, which can generate the neoteric photocatalytic systems. Finally, the main challenges and opportunities with respect to MoS₂ being a cocatalyst and coherent light–matter interaction of MoS₂ in photocatalytic systems are proposed.