Fluorescent lamp promoted formaldehyde removal over CeO2 catalysts at ambient temperature

Exploring an alternative strategy with high efficiency and low cost to abate formaldehyde (HCHO) in indoor environment, is of increasing significance for people's health. CeO₂ catalysts prepared by hydrothermal, precipitation and calcination methods were investigated for HCHO removal at ambient temperature. It is found that indoor fluorescent light visibly boosts the catalytic performance of CeO₂ catalysts for HCHO decomposition at ambient temperature. Among the CeO₂ catalysts, CeO₂ prepared from hydrothermal method (CeO₂–H) exhibits a superior catalytic performance and an excellent durability by eight recycle times. Based on the characterization and analysis, the excellent catalytic performance of CeO₂–H is mainly contributed by its abundance of surface oxygen vacancies, and photogenerated electrons and hole activated by fluorescent light. This work shows a potential practicability in HCHO pollution elimination by taking full advantage of the existing lighting in indoor environments.     

Highly dispersed and active Pd nanoparticles over titania support through engineering oxygen vacancies and their anchoring effect

Rational synthesis of highly dispersed and active metal nanoparticles (NP) for application in catalysis has been a hot but challenging research topic. Herein, we report a facile strategy for dispersing and stabilizing noble metal NP in a reducible metal oxide support (e.g., TiO₂) through engineering oxygen vacancies and their anchoring effect. The pre-reduction of TiO₂ support produces oxygen vacancies, and Pd NP prefer to occupy these vacancies with a strong meal-support interaction and near metallic state. A near monatomic Pd NP distribution over anatase TiO₂ support is obtained with this strategy. Significant activity enhancement is demonstrated in both oxygen activation and formaldehyde oxidation reactions by this catalyst design method. H₂, NaBH₄ and HCHO are suitable reducing agent for TiO₂, the pre-reduction catalysts by H₂, NaBH₄ and HCHO shows highly activity for formaldehyde oxidation. Such a work demonstrates support pre-reduction strategy is a facile way to prepare powerful supported noble metal catalysts.     

不同路线国V车用柴油机非常规排放对比研究

在AVL全流采样(CVS)发动机台架上,对2台国V柴油机进行了ESC、ETC测试循环,并利用FTIR气体分析仪对非常规气体排放进行了测试。通过对比不同技术路线(增压中冷+共轨+EGR+DOC+DPF和增压中冷+共轨+SCR)发动机的NO2、SO2、NH3、HCHO和NOx排放,对它们的排放特性进行了试验研究;同时还分析了两种路线的CO2排放和油耗情况。研究结果表明DOC+DPF可以使NOx中NO2的比例升高,ESC循环达到了24.3%;两种路线都可以使车用柴油机满足国V排放标准要求,但前者THC、CO、HCHO、NH3排放明显低于后者,后者NO2排放及NO2在NOx排放中的比例明显低于前者。SCR路线在油耗和CO2排放方面相对具有优势。     

Tailoring Effective FeOx/SiO2 Catalysts in Methane to Formaldehyde Partial Oxidation

A preparation method of highly effective methane to formaldehyde partial oxidation (MPO) FeO_x/SiO₂ catalysts (Fe 0.09--0.43 wt%) is reported, based on adsorption-precipitation (ADS/PRC) of Fe^II ions under controlled conditions. The performance of ADS/PRC catalysts in the MPO reaction at 650 °C has been compared with that of conventional systems prepared by incipient wetness (INC/WET) of silica carriers with aqueous solutions of Fe^III. The ADS/PRC method, likely enabling a higher dispersion of the active phase, provides very effective MPO catalysts featuring CH₄ turnover frequency (TOF) and HCHO productivity (STY_HCHO) values larger than those of the counterpart INC/WET systems.     

海绵状Ag2O/ZnO复合光催化剂的制备及对甲醛的可见光降解

为克服纳米ZnO晶体可见光光催化活性低的缺点,以六水合硝酸锌、六亚甲基四胺和二水合草酸为原料,采用液相共沉淀-热分解法制备了六方纤锌矿型海绵状ZnO,然后在碱性条件下复合纳米Ag₂O颗粒,得到海绵状Ag₂O/ZnO复合光催化剂,并采用XRD、FTIR、紫外-可见漫反射（UV-Vis DRS）、FESEM、TEM和BET测量仪对其进行了表征;采用可见光光源,甲醛（HCHO）液体为光催化反应模型物,研究了不同摩尔比下Ag₂O/ZnO复合光催化剂的暗吸附及光催化性能。结果表明,随着Ag₂O相对含量的增加,HCHO暗吸附效果出现先增大后减小的趋势,当Ag₂O与ZnO摩尔比为1∶5时,HCHO去除率达到43.34%;另一方面,在可见光下Ag₂O/ZnO复合光催化剂对HCHO的降解率呈先增大后减小的趋势,其中Ag₂O与ZnO的摩尔比为1∶10时取得最佳降解效果,经过90 min的可见光光照后HCHO降解率达到78%,总的HCHO去除率为85%。      

珠三角地区大气中HCHO、O3、NO2的监测与分析

利用长程差分吸收光谱技术于2008年10月15日至11月19日对珠三角地区江门市大气中的HCHO、O3、NO2等污染物进行了实时监测,结合气象数据,分析了江门地区主要污染物HCHO、O3、NO2的日变化特征;同时,对江门市的主要污染来源进行了分析。对比了HCHO和其他各类污染物浓度数据的相关性分析及变化趋势对比,结果表明江门地区的HCHO主要来源于二次污染。利用多元线性回归分析,进一步证明了该结论。     

A comparative study of formaldehyde and carbon monoxide complete oxidation on MnOx-CeO2 catalysts

MnOx-CeO2 composite catalysts were prepared by a coprecipitation method and tested for formaldehyde (HCHO) and carbon monoxide (CO) oxidation. X-ray photon spectroscopy (XPS) results indicated that the average oxidation state of surface Mn species in CeMn composite catalyst was higher compared to the pure MnOx. The enhancement of reactivity for HCHO oxidation was due to the activation of the lattice oxygen species in MnOx by the addition of CeO2, which was confirmed by the H2 temperature programmed reduction (H2-TPR) results. The remarkable enhancement of reactivity for CO oxidation by the addition of CeO2 was due to the active oxygen species generated on the CeO2 surface which directly participated in the reaction.     

Investigation on formaldehyde gas sensor with ZnO thick film prepared through microwave heating method

ZnO nanopowders were prepared through microwave heating method. ZnO thick film sensors were fabricated by using ZnO nanopowders as sensing materials. The phase composition and morphology of the material particles were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The gas-sensing properties of the sensors based on ZnO nano-materials were investigated. It was found that the sensor based on ZnO nano-materials (low power, 10× 10 min) exhibited very high responses to benzene and toluene when operating at 440 and 370 °C, respectively; but the sensor based on ZnO (low power, 10× 10 min) showed very low responses to benzene and toluene when operating at 205–215 °C. The sensor based on ZnO (low power, 10× 10 min) showed high response and good selectivity to dilute formaldehyde when operating at 210 °C; especially, the response to 0.001 ppm HCHO attained 7.4 when operating at 210 °C.     

一种可能的新的无醛整理剂—烷基四羧酸

本文详细介绍了一种新型的无醛整理剂(烷基四羧酸)及它们在纤维素纤维防皱整理中的应用,最后认为这类整理剂是人们值得重视的一类无醛整理剂。     

Partial oxidation of CH4 at low pressure over SiO2 prepared from Si

The oxidation of CH₄ with O₂ at low pressure was carried out over SiO₂ prepared from metal Si. The Si showed only total oxidation activity while the Si partly oxidized to SiO₂ showed high selectivities to CH₃OH and HCHO. The results on SiO₂ prepared from Si were compared with those over commercial silicas. The role of SiO₂ in the CH₄ oxidation was discussed.