Characterization of metal-containing molecular sieves and their catalytic properties in the selective oxidation of cyclohexane

Three types of metal-containing molecular sieves with AFI, AEL and CHA structures (Me = Co, Mn, Cr and V) were synthesized hydrothermally and characterized by XRD, XRF, TG, TPR, NH3-TPD and FT-IR. It was revealed that metals were incorporated into the framework of molecular sieves and induced the presence of charge centers. Both cobalt and manganese in the framework of AIPO-5, AlPO-11 and SAPO-34 were not reducible before the structure collapse. The redox behaviours of these catalysts in cyclohexane oxidation at 403 K using O-2 as oxidant were examined. CoAPO-11 exhibited best activity and good selectivities for the monofunctional oxidation products (88.5%). Cyclohexanol was the major product over most catalysts, whereas for Cr-containing molecular sieves, high selectivity of cyclohexanone was observed. Investigation of reaction mechanism based on CoAPO-11 and CrAPO-5 catalysts indicated that the decomposition of cyclohexyl hydroperoxide (CHHP), the intermediate in cyclohexane oxidation, followed the pathway: cyclohexanone <-- CHHP --> cyclohexanol -->cyclohexanone. (C) 2004 Elsevier B.V. All rights reserved.

长白山温带混交林林冠下层CO_2通量对生态系统碳收支的贡献

作为ChinaFLUX的重要组成部分,从2002年年底开始利用涡度协方差技术在长白山温带混交林林冠上层和下层进行连续通量观测,这为量化林冠下层CO2通量对整个森林生态系统碳收支的贡献提供了一条有效途径。利用2003年林冠上层和林冠下层的观测数据,研究表明林冠下层夜间的CO2通量与5 cm深度的土壤温度存在明显的指数正相关关系。林冠下层的呼吸通量与箱式法观测的土壤呼吸通量之间具有很好的一致性(R2=0.77),二者在全年都与整个森林的光合产物量相耦合,且都在7~8月份达到最大值。林冠下层的呼吸量和土壤呼吸量分别为770 g Cm-2a-1和703 g Cm-2a-1,占整个森林生态系统呼吸年总量的比重高达59.88%和54.69%。林冠下层的光合作用呈双峰型季节变化,两个峰值分别出现在5月中旬和8月下旬。尽管全年林冠下层光合产物量为87 g Cm-2a-1,对整个森林光合产物量的贡献率仅为5.69%,但林冠郁闭度低的4、5月和10月份,林冠下层的光合产物贡献率也分别达到19.99%、21.06%和14.53%。林冠下层净初级生产力的季节动态受该层呼吸作用的季节变异控制,林冠下层在全年都表现为碳源,其净碳排放速率在8月份达到最大。

陈化石油污染物降解菌的筛选

选择6株自堆腐处理2阶段的石油污染土壤中分离的真菌,另引进2株白腐真菌作为供试菌株,采用以河沙替代土壤,用人工投加污染物的实验方法,研究了有较强解脂酶活性的真菌对特稠油、胶质和沥青质的降解效果。结果表明,在好氧条件下,土壤中低浓度污染物(特稠油浓度3.76g·kg-1、胶质和沥青质浓度0.095g·kg-1)经过80d的堆腐处理后,黄孢原毛平革菌(PhanerochaeteChrysoporium)、采绒革盖菌(Cviolusversicolor)、木霉(Trichodermasp.)、小克银汉(Cunninghamellasp.)、曲霉(Aspergillussp.)、镰刀菌(Fusariumsp.)对特稠油有较好的降解效果,降解率分别为20.40%、19.14%、22.46%、15.88%、16.48%和14.95%。但仅采绒革盖菌和小克银汉对胶质+沥青质有一定的去除效果,其降解率分别达到11.47%和11.58%。本研究筛选的两菌株为强化难降解石油组分的去除提供了可能。

Study of a high power density sodium polysulfide/bromine energy storage cell

Nickel catalyst supported on carbon was made by reduction of nickelous nitrate with hydrogen at high temperature. Ni/ C catalyst characterization was carried out by XRD. It was found that the crystal phase of NiS and NiS2 appeared in the impregnated catalyst. Ni/ C and Pt/ C catalysts gave high performance as the positive and negative electrodes of a sodium polysulfide/ bromine energy storage cell, respectively. The overpotentials of the positive and negative electrodes were investigated. The effect of the electrocatalyst loading and operating temperature on the charge and discharge performance of the cell was investigated. A power density of up to 0.64 W cm(-2) ( V = 1.07 V) was obtained in this energy storage cell. A cell potential efficiency of up to 88.2% was obtained when both charge and discharge current densities were 0.1 A cm(-2).

Catalytic partial oxidation of n-heptane for hydrogen production

Partial oxidation of n-heptane (POH) for hydrogen generation was studied over several catalysts between 700 and 850degreesC. Modified Ni-based/gamma-Al2O3 catalyst exhibited not only good catalytic activity but also good carbon deposition resistance ability. Under the modified reaction conditions, 100% n-heptane conversion and 93% hydrogen selectivity can be obtained.

二级串联人工湿地处理稠油污水的季节变化

选取不同材料做基质,芦苇为湿地植物,构建了1#和2#二级串联潜流式人工湿地系统,对稠油采出污水进行现场处理试验研究。考察了水力负荷分别为0.18和0.09m3/(m2.d)的1#和2#湿地,不同季节(夏季和冬季)情况下的运行效果。结果表明,夏季人工湿地对石油类、COD、BOD5、TN、SS的去除率分别为79.22%、81.20%、89.67%、87.61%和89.47%;冬季则达到77.57%、78.98%、79.05%、71.35%、89.88%。

分散式污水生态处理系统及应用

介绍了一种基于生态工程技术的低费用、低能耗的分散式污水处理系统(生物—地下渗滤)。分析了2003—2005年该系统氮、磷去除效果的动态变化特征。结果表明,NH4+-N的去除受温度变化的影响较大,每年7—9月去除效果最好,12月和1—3月去除效果最差;温度对磷的去除影响很小;COD、SS、TP、细菌总数、NH4+-N等污染物的去除率分别达到89.2%±1.4%、86.8%±1.8%、88.2%±3.4%、98.3%±0.1%、62.8%±3.2%,出水水质符合生活杂用水水质标准(CJ251—89)和沈阳市污水处理中水回用标准,处理效果稳定。

镉胁迫对金银花生理生态特征的影响

采用水培试验方法,研究了不同浓度镉(Cd)(0、5、10、25和50mg·L-1)胁迫条件下藤本植物金银花的生长和生理特性.结果表明:与对照相比,Cd胁迫对金银花的生长未造成明显影响,在5～50mg·L-1Cd处理下,其生物量无明显差异(P>0.05),在低浓度Cd(5mg·L-1)处理下生物量有所增加,叶、根生物量和总生物量分别增加了2.88%、2.33%和1.25%,说明金银花对Cd具有较强的抗性.在低浓度Cd胁迫下,植物各器官的含水量和可溶性蛋白含量均有所降低,而根系和叶片的丙二醛含量分别增加51.90%和23.07%,叶绿素和类胡萝卜素含量则增加15.87%和24.89%,超氧化物歧化酶活性也显著增强.随着Cd浓度的增高,金银花体内的叶绿素和类胡萝卜素含量,以及超氧化物歧化酶活性均有所降低.

土壤类型和添加有机物料对铵态氮回收的影响

探讨NH4+-N回收率在不同因素下的变化规律。【方法】以黄土高原从北向南不同地区的典型土壤类型为对象,采用Bremner浸取法,研究了土壤类型、植被类型、施肥模式及添加有机物料对铵态氮回收率的影响。【结果】不同类型土壤及不同类型植被间NH4+-N回收率存在极显著差异(P<0.01)。黄土正常新成土的NH4+-N回收率最高(88.8%),极显著大于其他土壤,土垫旱耕人为土的NH4+-N回收率最低(81.0%),简育干润均腐土和干润砂质新成土介于二者之间;不同类型植被间,林地土壤的NH4+-N回收率(91.0%)极显著高于其他类型植被土壤,其他类型植被土壤的NH4+-N回收率表现为农田(85.5%)>裸地(83.8%)>草地(83.6%),但三者之间差异不显著。添加有机物料后,土壤NH4+-N回收率极显著增加(P<0.01),不添加有机物料对照土壤的NH4+-N回收率为84.3%,添加长毛草和苜蓿后的NH4+-N回收率分别为86.6%和85.9%。长期施肥对土壤NH4+-N的回收率无显著影响(P=0.436 5>0.05)。【结论】NH4+-N回收率与粘粒含量呈弱负相关,与有机质含量呈正相关,粘土矿物对N...

可溶性有机氮在评价土壤供氮能力中的作用与效果

淹水培养法提取态可溶性有机氮在评价土壤供氮能力方面具有重要意义。【方法】通过研究黄土高原物理化学性质差异较大的10种农田土样起始可溶性有机氮(SON)、矿质氮(Nmin)及间歇浸提长期淹水培养期间可溶性有机氮、铵态氮累积量、易矿化和难矿化氮素矿化势(分别ND和NR表示)及其与作物吸氮量的关系,分析SON在评价土壤供氮能力中的作用与效果。【结果】供试土样起始SON平均为23.9mg·kg-1,是起始可溶性总氮的28.8%、全氮的2.4%。淹水培养提取态可溶性氮(TSN)中,SON所占比例更高,几乎与铵态氮相当。经过217d淹水培养,浸提出的SON平均为118.1mg·kg-1,占TSN累积量的46.4%。ND与全氮关系密切:在不包括与包括SON时,二者的相关系数分别为0.92(P<0.01)和0.88(P<0.01)。不同土壤ND和易矿化氮矿化速率(KD)差别很大,干湿砂质新成土和黄土正常新成土的ND小于土垫旱耕人为土。考虑SON后KD值减小,而难矿化氮矿化速率(KR)增加。【结论】淹水培养期间铵态氮累积量是评价可矿化氮的较好指标,不仅适宜于第一季作物,而且也适用于连续两季作物;SON累积量不能单独作为...

沈阳东陵区油松栎林群落特征及物种多样性研究

以沈阳市东陵区油松栎林群落为对象,分析了群落特征,结果表明,油松栎林群落共有种子植物161种,分属49科121属,区系组成丰富。在植物区系地理成分上,种的分布类型以温带性质居多,共143种,占总种数的88.82%,表明了群落植物区系组成的温带亲缘关系;在群落结构上,油松栎林群落以地面芽植物最多,占36.0%;群落可分为乔木层、灌木层和草本层3个层次;种间联结性以山里红与黄波罗呈显著正关联外,其他种间联结性都较低。群落木本植物科-属-种组成多样性大小顺序为属-种多样性>科-属多样性>科-种多样性。

施肥对黑土土壤微生物生物量碳的作用研究

长期施肥对黑土耕地表层土壤微生物生物量碳 (MBC)的作用研究结果表明 ,NPK化肥配施可保持休闲地土壤微生物生物量碳含量至 1.6g/kg水平 ;高量有机肥与无机肥配施可比休闲地土壤微生物生物量碳含量提高 1.96～ 2 .75倍 ;长期耕种与施肥对土壤微生物生物量碳含量产生衰减影响 ;各处理土壤微生物生物量碳含量增加依次为M2 +NPK(+14 1.2 5 % ,1990年始处理 ) >M4+NPK(+12 6 .88% ) >M2 +NPK(+10 1.2 5 % ,1980年始处理 ) >M4+CK(+80 .6 3% ) >(M1+NPK)× 1.5 (+13.13% ) >NPK(+8.12 % ) ,各处理土壤微生物生物量碳含量减少依次为M0+NPK(- 3.75 % ) >M1+NPK(- 17.5 0 % ) >M2 +CK(- 30 .6 3% ) >CK(- 4 7.5 0 % ) >M0 +CK(- 6 1.88% )。

细河流域土壤中重金属的污染现状及潜在生态风险

分别以《土壤环境质量标准》(GB15618—1995)中的二级标准和沈阳市土壤环境背景值作为参比值,调查沈阳市细河流域表层(0～20cm)土壤中的重金属含量与富集情况,对细河流域重金属富集系数和超标率进行探讨,并结合Mller地累积指数法和Hakanson潜在生态风险指数法对污染情况进行生态风险评价.结果表明,细河流域土壤w(Hg),w(Cd),w(Pb)和w(Zn)差异显著,4种重金属含量显著正相关.流域内土壤中w(Cd)严重超出土壤环境标准值,超标样品数量占67.88%;其次为Zn和Hg,超标样品数量分别占4.87%和3.41%,Pb未超标.4种重金属含量均高于土壤背景值,表现出明显的累积效应,重金属的富集顺序为Cd>Hg>Pb>Zn;细河流域土壤中Hg,Cd,Pb和Zn具有不同程度的潜在生态风险;Pb除在细河上游流域局部污染区土壤中具有高风险外,其余均为一般风险;Zn在全流域污染区均属于一般风险;Hg和Cd在全流域污染区均为极高风险.

新型烟气脱硫脱氮吸附催化剂的制备

以褐煤为主原料研制出能同时进行燃煤烟气脱硫脱氮的吸附催化剂———褐煤基吸附催化剂,研究了影响褐煤基吸附催化剂性能的因素,确定了褐煤基吸附催化剂制备的工艺流程及最佳工艺条件。研究结果表明:原料配比、干馏温度、活化温度、活化时间等影响褐煤基吸附催化剂性能;在最佳工艺条件下,所制备的褐煤基吸附催化剂的转鼓强度为94%~96%,碘吸附率为38%~54%,脱硫率为88%~96%,脱氮率为70%~94%。

On Combining Morphological Component Analysis and Concentric Morphology Model for Mammographic Mass Detection

Mammographic mass detection is an important task for the early diagnosis of breast cancer. However, it is difficult to distinguish masses from normal regions because of their abundant morphological characteristics and ambiguous margins. To improve the mass detection performance, it is essential to effectively preprocess mammogram to preserve both the intensity distribution and morphological characteristics of regions. In this paper, morphological component analysis is first introduced to decompose a mammogram into a piecewise-smooth component and a texture component. The former is utilized in our detection scheme as it effectively suppresses both structural noises and effects of blood vessels. Then, we propose two novel concentric layer criteria to detect different types of suspicious regions in a mammogram. The combination is evaluated based on the Digital Database for Screening Mammography, where 100 malignant cases and 50 benign cases are utilized. The sensitivity of the proposed scheme is 99% in malignant, 88% in benign, and 95.3% in all types of cases. The results show that the proposed detection scheme achieves satisfactory detection performance and preferable compromises between sensitivity and false positive rates.