High-throughput approach to the catalytic combustion of diesel soot II: Screening of oxide-based catalysts

Following the development of a high-throughput (HT) methodology for the evaluation of diesel soot oxidation catalysts in a 16 parallel channels reactor, a library of over 60 catalysts was tested under optimized conditions. The catalyst compositions were chosen to include solids which specific properties like oxygen storage capacity, oxygen mobility and ionic conductivity. The key parameters for high activity appear related to the presence of active and mobile surface oxygen species, and to an appropriate catalyst particle size in order to favour the number of contacts with the soot. In contrast, high oxygen storage capacity and bulk oxygen ion mobility do not appear as relevant properties for high catalytic activity. Nine new formulations were found to perform better than the reference catalyst “high surface area (HSA) ceria” (Rhodia).     

Assessment of early-age cracking of high-performance concrete in restrained ring specimens

High-performance concrete(HPC)is stronger and more durable than conventional concrete.However,shrinkage and shrinkage cracking are common phenomena in HPC,especially early-age cracking.This study assessed early-age cracking of HPC for two mixtures using restrained ring tests.The two mixtures were produced with water/binder mass ratio(mW/mB)of 0.22 and 0.40,respectively.The results show that,with greater steel thickness,the higher degree of restraint resulted in a higher interface pressure and earlier cracking.With steel thickness of 6 mm,19 mm,and 30 mm,the age of cracking were,respectively,12 days,8 days,and 5.4 days with the mW/mB=0.22 mixture;and 22.5 days,12.6 days,and 7.1 days with the mW/mB= 0.40 mixture.Cases of the same steel thickness show that the ring specimens with a thicker concrete wall crack later.With the mW/mB = 0.22 mixture,concrete walls with thicknesses of 37.5 mm,75 mm,and 112.5 mm cracked at 3.4 days,8.0 days,and 9.8 days,respectively;with the mW/mB= 0.40 mixture,the ages of cracking were 7.1 days,12.6 days,and 16.0 days,respectively.     

利用催化裂化烟气中CO生产碳酸二甲酯

提出用变压吸附法提纯催化裂化再生烟气或炼钢高炉尾气中的CO，通过甲醇液相氧化羰基化法生产DMC的工艺路线。这对提高企业经济效益，减轻环境污染，促进资源的合理利用，有重大而深远的意义。     

预防混凝土早期开裂及过早碳化的技术措施

本文参考国内外资料,阐述了现阶段混凝土开裂及过早碳化的原因、危害和一般防治方法。     

催化裂化吸收稳定系统改进流程对比分析

利用流程模拟技术对催化裂化吸收稳定系统不同流程进行模拟计算，从产品收率、系统能耗的角度出发讨论不同流程优劣，为该过程的工艺改进提供参考和启示。计算结果表明，压缩富气直接进解吸塔的改进流程较常规流程热负荷下降1026%、冷却负荷下降1677%、液化气中丙烯产量增加78 kg/h；稳定塔侧线轻汽油作补充吸收剂流程较常规流程热负荷下降808%、冷却负荷下降062%、液化气中丙烯产量增加58 kg/h，但是C4损失量增加299 kg/h。压缩富气直接进解吸塔的改进流程效果明显，具有非常好的应用前景，而对于稳定塔侧线轻汽油作补充吸收剂流程的适用条件有待进一步研究。     

Numerical study on microstructured reactor with chaotic heat and mass transfer and its potential application for exothermic process

Design of microstructured reactors with thermal control function is investigated through numerical simulation. It consists of one middle channel for handling chemicals and two other channels attached to its top and bottom for cooling purpose. Three designs are examined. Reactor A uses simple straight channels. In reactor B, chaotic flow is applied to the middle channel, and in reactor C chaotic flow is applied to all the three channels. Results show that in comparison with the straight channel, the Nusselt number in current design is greatly improved through chaotic flow. Rapid mixing is also achieved. Potential application of the design for continuous exothermic process is analyzed. For reactor A, it is not workable as the temperature of the chemical solution continuously increases over the channel. In comparison, for both reactors B and C the temperature can be well controlled within the required range. As the coolant flow in reactor C is also chaotic, it provides a higher heat removal capacity.     

Tensile fatigue behavior of plain-weave reinforced Cf/C–SiC composites

The fatigue behavior of plain-weave C_f/C–SiC composites prepared by liquid silicon infiltration (LSI) was studied under cyclic tensile stress at room temperature. The specimens were loaded with stress levels of 83% and 90% of the mean static tensile strength for 10⁵ cycles. The cross-sections and fracture surfaces of the fatigued specimens were examined by optical microscopy (OM) and scanning electron microscopy (SEM), respectively. The results show that the specimens can withstand 10⁵ fatigue cycles with a stress level of 90% of the static tensile strength. The retained strengths after fatigue for 10⁵ cycles with stress levels of 83% and 90% are about 19% and 11% higher than the static tensile strength. Due to the observation of the microstructures a relief of the thermal residual stress (TRS) caused by stress-induced cracking is probably responsible for the enhancement. Furthermore, the fracture surfaces indicate that the fatigue stress results in interfacial debonding between the carbon fiber and matrix. Additionally, more single-fiber pull out was observed within the bundle segments of fatigued specimens.