Study on methane conversion to syngas over nano Pt-CeO2-ZrO2/MgO catalysts: Structure and catalytic behavior of catalysts prepared by using ion exchange resin method

Nano Pt-Ce0₂-Zr0₂/MgO catalysts with 0.8 wt.% Pt, 3.0 wt.% Ce0₂ and 3.0 wt.% Zr0₂ were prepared by wet impregnation mothod. Support MgO was obtained using ion exchange resin method or using commercial MgO. S_BET, XRD, TEM and C0₂-TPD were used to characterize the supports and catalysts. CH₄-C0₂ reforming to synthesis gas was performed to test the catalytic behavior of the catalysts. The catalysts prepared using ion exchange resin exhibited more regular structure, more basic sites and higher stability of Pt and MgO than prepared from commercial MgO. At 1073 K, atmospheric pressure, and at high gas hourly space velocity of 36,000 mL/(g-hr) with a stoichiometric feed of CH₄ and C0₂, the catalyst supported on the MOH(GD)-IE showed a higher and more stable activity for CH₄-C0₂ reforming reaction than the catalyst prepared using commercial MgO. The characterisation results demonstrated that the high activity and stability of the catalyst stem from the high dispersion of Pt, the stable structure and the high resistance to carbon deposition on the catalyst.     

我国硒污染分析与电解锰行业控制对策

硒是生命活动中的重要元素,世界卫生组织(WHO)1973年确认硒是人类生命必须14种微量元素中的第一线微量元素。硒的营养与中毒的界限是所有元素中最小的一个,若不足,则生物效应为"存活,缺乏",若过量,则"毒性,致死"。为了有效提高电解锰生产过程中的电流效率,国内企业广泛使用二氧化硒(SeO2)作为添加剂,导致操作工人长期暴露在硒污染作业环境中,同时锰渣中挟带大量的硒污染物进入到外环境中,存在着严重而明显的环境和生态隐患。因此,研究分析电解锰行业硒污染及其控制技术具有其必要性及重要性。     

某聚合物驱油先导实验职业卫生调查

对某采油厂聚合物驱油先导试验项目进行了职业卫生调查,以明确有害因素存在的岗位部位、种类、危害程度,并对职业病危害控制措施及效果进行调查分析。     

狮子洋水道水质变化趋势及其保护措施建议

近几年随着社会经济的快速发展,位于珠江三角洲的狮子洋水道水质发生了明显变化,通过不同年份水质监测结果的分析及比较,说明了狮子洋水质的变化趋势,同时本文提出了相关保护措施建议。     

Isotopic evidence of natural uranium and spent fuel uranium releases into the environment

Uranium and plutonium isotopes were measured in soils, sediments and waters in an area subject to the past and present discharges from the uranium conversion plant of Malvési (France). The isotopes (236)U and (239)Pu are well known activation products of uranium and they prove to be powerful tracers of spent fuel releases in soils and sediments. On the other hand (234)U and (238)U activities measured in waters can be used to distinguish between releases and background uranium sources. Such findings contribute to improve the monitoring of the actinides releases by nuclear fuel facilities (mining sites, conversion, enrichment and fuel plants, reprocessing plants).     

Degradation of 2,4,6-trichlorophenol in aqueous systems through the association of zero-valent-copper-mediated reduction and UVC/H2O2: effect of water matrix and toxicity assessment

Environmental Science and Pollution Research - The presence of toxic chlorinated compounds in drinking water, generated during the disinfection step in water treatment plants, is of great concern...     

Application of WRF-Chem to simulate air quality over Northern Vietnam

Environmental Science and Pollution Research - The WRF-Chem (Weather Research and Forecasting with Chemistry) model is implemented and validated against ground-based observations for meteorological...     

外源硫酸盐介入下沉积物磷释放、解磷微生物及磷酸酶活性的变化

人类生产活动导致湖泊水体硫酸盐浓度日益增加,硫酸盐与沉积物中磷之间的关系引起关注.该研究以武汉东湖水和沉积物为研究对象进行实验室模拟,研究为期近一年且温度变化的条件下外源硫酸盐对沉积物释磷及微生物的作用.结果表明,硫酸盐输入使沉积物pH和氧化还原电位(E h)总体呈降低趋势.外源硫酸盐促进了沉积物磷的释放,输入硫酸盐(S500)与对照(CK)之间的上覆水存在显著差异(p0.01),S500的上覆水中总磷浓度最高值达0.33 mg·L-1,为对照的2倍.湖泊沉积物中有机磷解磷菌的数量高于无机磷解磷菌,上层沉积物解磷菌的数量和沉积物总磷的含量之间呈负相关.S500的沉积物中磷酸二酯酶活性高于磷酸单酯酶活性,且不同分层沉积物磷酸单酯酶活性和磷酸二酯酶活性之间的正相关性达到显著水平.温度升高,磷酸酶的活性逐渐增强,促使沉积物内源磷释放量增加.     

河西走廊中段荒漠绿洲土壤生态化学计量特征

为探究荒漠绿洲土壤C、 N、 P和K的含量变化及生态化学计量特征,阐明其对环境因子的生态学响应,选择河西走廊中段张掖临泽荒漠绿洲10块样地,采集表层土壤样品,测定土壤C、 N、 P和K含量,揭示不同生境中土壤养分含量变化和化学计量比的分布特征以及与其他环境因子间的相关关系.结果表明：(1)土壤C在各样点分布不均匀且具有明显的异质性(R=0.761,P=0.06).其中,ω(C)在绿洲平均值最高,为12.85 g·kg^-1,过渡带次之,为8.65 g·kg^-1,荒漠最低,为4.1 g·kg^-1;(2)土壤K含量除在盐碱地含量较低外,在荒漠、过渡带和绿洲之间均无显著变化且含量较高;(3)土壤C∶N平均值为12.92,C∶P平均值为11.69,N∶P平均值为0.9,均低于全球土壤平均水平(13.33、 72.0、 5.9)和中国土壤平均水平(12、 52.7、 3.9);(4)土壤含水量为影响荒漠绿洲土壤C、 N、 P、 K和生态化学计量特征的最大影响因子,贡献率为86.9%,其次为土壤酸碱度和土壤孔隙度,贡献率分别为9.2%...     

基于信息熵的武汉市城市生态系统演化分析研究

基于信息熵的分析方法,在前人的研究基础上,以武汉市2000~2010年城市生态系统发展为例,通过计算城市生态系统输入-输出熵流、代谢熵产生和系统总熵变,分析系统演化发展规律及原因;分别采用综合发展度和协调发展度评估城市的可持续发展水平,并将其进行指数化表征。分析结果表明：近11 a内系统熵流和总熵总体是呈现振荡式下降趋势,而熵产生先升后降,武汉市总体不断向着健康、有序方向发展,但有序度不稳定;近年来协调发展度和综合发展度二者保持同时增长,说明武汉市城市生态系统不断向着可持续方向发展,但武汉市目前仍处于初级协调发展水平