g-C3N4 doping TiO2 recovered from spent catalyst for H2 evolution from water

Spent catalysts of selective catalytic reduction (SCR) contain a high content of TiO₂ (>70 wt%). The effective recovery of TiO₂ from spent SCR catalysts and its reuse in photocatalytic hydrogen production is of great importance for environmental protection. In this study, the recovered TiO₂ from the spent SCR catalyst was recovered by the alkali washing method, and the purity of the recovered TiO₂ reached 94.7%. g-C₃N₄ as a co-catalyst and enhanced the separation efficiency of the photogenerated electron-hole pairs of the TiO₂ photocatalyst. The composite photocatalyst R–TiO₂/g-C₃N₄ prepared by directly mixing the recovered TiO₂ with g-C₃N₄ significantly improved the photocatalytic activity. The experimental design of the photocatalyst synthesis was optimized using the Design Expert software. The results showed that the recovered TiO₂ was 0.334 g when the g-C₃N₄ was 0.046 g and the ultrasonic time was 163 min. Moreover, the hydrogen production rate reached 443.105 μmol g⁻¹ h⁻¹ within 4 h.     

48V起动发电一体式电机提升发动机排温的试验研究

基于48 V 起动发电一体式电机（Belt-driven Starter Generator,BSG）的起动机和发电机双重功能,在全球轻型车统一测试循环（World Light-duty Test Cycle ,WLTC）起始阶段,控制BSG电机行使发电功能,在飞轮端输出功率不变的条件下,提升发动机总功率,从而快速提升排气温度;利用BSG电机的快速起动功能,在WLTC循环的怠速工况关闭发动机,避免出现低温排气流,从而起到后处理保温作用。结果显示,在WLTC循环过程中,涡轮后排温达到选择性催化还原系统（Selective Catalyst Reduction,SCR）起燃温度（预设为200℃）的时间由780 s缩短到650 s,尿素喷射起喷时刻提前了约130 s;同时,在荷电状态（State Of Charge,SOC）略微下降的条件下,WLTC循环油耗降低2.4%。     

Multi-stage ammonia production for sorption selective catalytic reduction of NOx

Sorption selective catalytic reduction of nitrogen oxides (NO_x) (sorption-SCR) has ever been proposed for replacing commercial urea selective catalytic reduction of NO_x (urea-SCR), while only the single-stage sorption cycle is hitherto adopted for sorption-SCR. Herein, various multi-stage ammonia production cycles is built to solve the problem of relative high starting temperature with ammonia transfer (AT) unit and help detect the remaining ammonia in ammonia storage and delivery system (ASDS) with ammonia warning (AW) unit. Except for the single-stage ammonia production cycle with MnCl₂, other sorption-SCR strategies all present overwhelming advantages over urea-SCR considering the much higher NO_x conversion driven by the heat source lower than 100°C and better matching characteristics with low-temperature catalysts. Furthermore, the required mass of sorbent for each type of sorption-SCR is less than half of the mass of AdBlue for urea-SCR. Therefore, the multifunctional multi-stage sorption-SCR can realize compact and renewable ammonia storage and delivery with low thermal energy consumption and high NO_x conversion, which brings a bright potential for efficient commercial de-NO_x technology.     

晶闸管弧焊整流数字控制设计

针对大功率弧焊电源的工作环境和工作特点,对电焊机输出电压和电流进行取样,并进行数字控制的PI运算,适时控制电焊机输出的电压和电流。其实现方法是采用DSP芯片实现整个控制系统的功能,由FPGA实现晶闸管的触发导通,同时通过采样负载电压和电流进行双闭环PI控制,从而控制输出电压和电流的大小。通过理论分析,最后实验验证了该控制系统能根据焊接工件的不同输出不同的电压、电流值,同时系统运行稳定、可靠。     

Ammonium bisulfate formation temperature in a bench-scale single-channel air preheater

Ammonium bisulfate (ABS) forms in coal-fired power plant exhaust systems when ammonia slip from the NO_x control system reacts with the sulfur oxides and water in the flue gas. The critical temperature range for ABS formation occurs in the air preheater, where ABS is known to cause corrosion and pluggage that can require unplanned outages and expensive cleaning. To develop mitigation strategies for the deleterious effects of ABS in air preheaters, it is important to know its formation temperature and deposition process. This paper describes a bench-scale experimental simulation of a single-channel air preheater, with the appropriate temperature gradient, used in conjunction with simulated coal combustion flue gas, including sulfur oxides, ammonia, and water vapor, to investigate the formation of ABS. Formation was observed optically, and the formation temperature, as well as deposition characteristics for a realistic range of reactant concentrations are presented and compared with previous studies on ABS formation. This study presents data at realistic concentrations not earlier tested, and the reported data has smaller experimental uncertainty than previously obtained. We found that the measured ABS formation temperatures under air preheater channel conditions lies between the temperatures reported by others, and is in the range of 500-520 K for typical flue gas concentrations of ammonia and sulfur oxide species. The results also show that, at least for this experimental configuration, ABS forms predominantly as an aerosol in the gas phase rather than as a condensate on the channel walls.     

SCR of NO over Ir/Al2O3 Catalysts. Importance of the Activation Procedure and Influence of the Dispersion

For SCR of NO the study of Ir/Al₂O₃ solids shows the importance of the activation procedure under mixtures containing CO (NO–C₃H₆–CO–O₂ or NO–CO–O₂). The selective reductant remains C₃H₆, however. The activation goes with an iridium particles sintering without Ir loss.     

Nanosized titania derived from a novel sol-gel process for ammonia gas sensor applications

Highly redispersible anatase nanoparticles were prepared by a novel sol-gel based hydrothermal process for gas sensing applications. Thin titania films composed of nanoparticles were deposited on Au interdigital electrodes by dip-coating, annealed and tested in a gas test bench at 350 °C. The anatase films showed a very high sensitivity towards ammonia and no cross interference by CO₂, O₂ and C₃H₈. To classify the sensor as an ammonia gas sensor, a comparison with other sensor designs from literature has been performed.     

尿素制氨工艺在SCR烟气脱硝工程中的应用

介绍了SCR烟气脱硝工程中几种尿素制氧工艺的系统及特点，对其在实际工程中的应用进行了比较，并提出工程应用中应注意的问题。     

Knowledge and Know‐How in Emission Control for Mobile Applications

Abstract

Concerns about emissions of carbon dioxide have created a need to develop more fuel‐efficient vehicles. Diesel engines are generally more efficient than gasoline engines but improvements in the latter can be achieved by operating under lean‐burn conditions. With both diesel and lean‐burn gasoline engines, the nitrogen oxides are emissted under oxidising conditions. It is scientifically very challenging to reduce nitrogen oxides under oxidising conditions. After a short survey of conventional three‐way catalysts, and the associated fundamental aspects of NO_x reduction under stoichoimetric conditions, this review focuses on the knowledge and know‐how that has been developed for lean engine emission control. Early research on hydrocarbon selective catalytic reduction on zeolite, oxide, and metal‐based systems is examined, and some of the key mechanistic models are described. Since none of these systems are of sufficient activity and stability to satisfy current legislation attention has turned to NO_x storage and reduction systems. The basic principles of these are described, and the present state of knowledge regarding the mechanisms of storage and regeneration are discussed. The many apparent discrepancies are highlighted and an attempt is made to rationalise the current state of knowledge by taking into account the varying experimental conditions reported nit he literature. For diesel engines, NO_x storage and reduction is not an ideal solution and so the final section of this review is concerned with silver‐based catalysts and especially with the dramatic effect of small amounts of hydrogen on the efficiency of these catalysts for hydrocarbons selective catalytic reduction.     

交流变频调速技术在宝钢股份宽厚板厂的应用

文章详尽地介绍了宝钢股份新建的宽厚板轧钢厂广泛用交流变频调速技术的情况，阐述了其可观的效果，同时指出了方案选择的不足之处。