葡萄糖基水热炭构建Co―N―C催化剂及其硝基苯催化加氢反应性能

硝基苯选择性加氢反应是生产苯胺的重要方法,其关键在于开发一种具有高效选择性且低成本的绿色催化剂。本文基于葡萄糖水热炭化得到水热炭前驱体,结合尿素和硝酸钴一步高温热解制备了一种高度分散的富含Co纳米颗粒的氮掺杂多孔炭材料,将其作为催化剂用于硝基苯加氢反应。详细研究了热解温度对催化剂结构和催化活性的影响,证实了催化活性主要受催化剂的比表面积、Co掺杂量及其Co-Nx配位效应的影响。结果表明,将含10%Co源制备的前驱体800℃热解得到的催化剂(Co@NCG-800)表现出优异的硝基苯催化加氢性能,在以异丙醇为溶剂、100℃和1 MPa氢压下反应2.5 h时可实现硝基苯的转化,苯胺选择性高达99%。催化剂循环使用6次后的硝基苯转化率和苯胺选择性几乎保持不变。优异的循环稳定性能可归因于多孔炭材料中的氮元素和Co纳米颗粒的强相互作用,同时磁性Co纳米颗粒使得催化剂具有较好的分离特性和重复使用性。

引黄泥沙与腐殖酸对滨海粘质盐土主要水分常数的影响

为确定不同引黄泥沙和腐殖酸配施量对滨海粘质盐土田间持水量和大孔隙水含量的影响,探究最适宜的引黄泥沙和腐殖酸配施量。采用双因素方差分析法对土壤水分含量进行分析,研究了不同引黄泥沙和腐殖酸配施量对土壤凋萎系数、毛管断裂含水量、田间持水量、饱和含水量和大孔隙水含量的影响。结果表明:①引黄泥沙和腐殖酸配施可以提高土壤凋萎系数、毛管断裂含水量、田间持水量、饱和含水量,其中S4T1、S4T2、S4T3、S4T4四个处理的土壤凋萎系数比对照处理分别增加了82.10%、82.68%、81.31%和81.92%;S4T1、S4T2、S4T3、S4T4四个处理的土壤毛管断裂含水量比对照处理分别增加了31.70%、42.03%、43.73%和46.70%;S4T4、S4T3、S4T2和S4T1四个处理的土壤田间持水量比对照处理分别增加了46.70%、43.73%、42.03%和31.70%;S3T4、S2T4、S3T2、S3T3四个处理的土壤饱和含水量比对照处理分别增加了15.41%、14.78%、14.49%和14.03%。②引黄泥沙和腐殖酸配施可以提高土壤大孔隙水含量,其中S1T3、S1T4、S2T2、S2T3四个处理的土壤大孔隙水含量比对照处理增加了16.12%、17.97%、16.34%、16.32%。综合考虑,在改良黄河三角洲地区粘质盐土时,引黄泥沙和腐殖酸配施量为150 t/hm2和0.9 t/hm2最合适。

磁性污泥生物炭活化过硫酸盐降解罗丹明B

采用微波热解法制备磁性污泥生物炭(MBC),并通过XRD、FT-IR和SEM对其晶体结构、表面官能团及形貌进行表征。以罗丹明B(RhB)为目标污染物,研究MBC活化过硫酸盐(PDS)的性能。结果表明MBC活化PDS能够有效去除水体中RhB,效果优于磁性Fe_(3)O_(4),归功于MBC具有丰富的官能团和发达的孔隙结构。此外,探究催化剂投加量、PDS添加量、温度和pH值对MBC活化PDS降解RhB的影响。MBC活化PDS降解RhB主要通过非自由基过程,其中单线态氧(^(1)O_(2))是主要的反应活性物种。

Joint power allocation and multi-relay selection scheme based on system outage probability

An amplify-and-forward （AF） based multi-relay network is studied. In order to minimize the system outage probability with a required transmission rate, a joint power allocation （PA） and multi-relay selection scheme is proposed under both total and individual power constraints （TIPC）. In the proposed scheme, the idea of ordering is adopted to avoid exhaustive search without losing much system performance. Besides the channel quantity, the ordering algorithm proposed in this article also takes relays＇ maximal output ability into consideration, which is usually ignored in traditional relay ordering algorithms. In addition, simple power reallocation method is provided to avoid repetitive PA operation during the process of searching all possible relay subsets. By Adopting the idea of ordering and using the proposed power reallocation method lead to remarkable decrease of the computation complexity, making the scheme easier and more feasible to implement in practical communication scenarios. Simulations show that the proposed multi-relay selection scheme provides similar performance compared to the optimal scheme with optimal PA and exhaustive search （OPAES） but with much lower complexity.