Preparation of Ru/CNTs Nano-material by Polyol Reduction-deposition Method and Its Catalytical Performance for Ammonia Decomposition

第一作者简介: 武小满, 女, 博士, 副教授, 从事催化化学研究及教学工作。E- mail xm anw u77@ yahoo. com. cn[中文文摘]通过乙二醇液相还原法将少量金属Ru沉积在碳纳米管(简称CNTs)上,TEM、XRD表征结果表明,该法明显提高了Ru在CNTs上的分散度,Ru微晶的粒径在3~4 nm。氨分解反应结果表明,采用乙二醇液相还原法在降低Ru负载量的同时还明显提高了Ru/CNTs的催化氨分解活性。在0.4 MPa、773 K、空速GHSV100%NH3=30 000 mL/(h.g)反应条件下,在液相还原法制备的4.2%Ru/CNTs催化剂上氨分解转化率可达48.5%,约为同条件下浸渍法所得5%Ru/CNTs的1.3倍,液相还原最佳配比5.7%Ru/γ-Al2O3的1.2倍。表观活化能测试结果显示用CNTs代替γ-Al2O3作为载体或分散相并不引起所负载Ru催化剂上NH3分解制H2反应的表观活化能发生明显变化。[英文文摘]Nowadays catalytic decomposition of ammonia is regarded as a method to obtain COfree hydrogen for its application in proton exchange membrane fuel cell.In this paper,with carbon nano-tubes(as CNTs) as substrate,a series of metallic Ru/CNTs were prepared using glycol reduction-deposition method which enhanced markedly dispersion of Ru on CNTs with the Rux0-crystallite size at 3~4 nm characterized through TEM and XRD.Under reaction conditions of 0.4 MPa,773 K and GHSV100%NH3 = 30 000 mL/(h·g),the observed NH3- decomposition conversion over the 4.2% Ru/CNTs catalyst(prepared through ethylene-glycol reduction-deposition) reached 48.5%, which was about 1.2 times as high as that of the 5.7% Ru /γ-Al2O3 catalyst prepared by the samemethod, and about 1.3 times as high as that of the 5% Ru /CNTs catalyst prepared by conventional incip ientw etnessmethod. Over the 4% Ru /CNTs catalys,t 100% o fNH3 - decomposition w as a ttained at 870 K; w hile over 5% Ru /CNTs prepared by conventional incipient wetness method, the reaction temperature as high as 900 K w as requ ired for the same (100%) conversion. At 870 K, the observed NH3 - decomposit ion conversion w as only 81. 7% over the 5. 7% Ru /γ-Al2O3 catalys.t It was experimentally also found that using the CNTs in place of γ-Al2O3 as support of them etalRu- catalyst did not cause amarked change in the apparent activation energy (Ea) for the reaction of NH3- decomposition to yieldH2.国家重点基础研究发展规划“973”项目(2005CB221400); 国家自然科学基金项目(20473063和20590364

Catalytical performance for ammonia decomposition on Ru/CNTs nano-material prepared by polyol reduction-deposition method

武小满( 1977-),女,副教授,主要研究方向:纳米材料和催化化学。 E-mail：[email protected][中文文摘]近年来各国对环境保护日益关注,为了减少甚至消除汽车、小型发电站等带来的污染,供给质子膜燃料电池(PEMFC)的现场制氢技术的研究受到关注。以含碳物质如甲醇、甲烷制得的氢气中不可避免含有COx(x=1,2),微量COx就会严重毒化电极,而氨分解制氢环境友好,经燃料电池单元综合利用后,尾气仅为N2和H2O并可直接排空,全过程不会产生有害气体,因此成为燃料电池用氢技术研究的热点。作为第二代氨合成催化剂的活性组分,纳米金属钌也是氨分解催化剂的研究重点[1];目前大部分的氨分解Ru催化剂主要采用浸渍法制得[1-3]。多元醇液相化学还原法[4-6]是近年来新发展起来的纳米金属催化剂/材料制备方法,因具有工艺简单,结果易重复,产物的粒径及其分布、形貌、纯度易控等特点而倍受人们的关注。另一方面,碳纳米管(CNTs)是一类新奇的碳素纳米材料,近年来被用作新型催化剂载体或促进剂的研究与日俱增,应用研究主要集中在液相和气相的选择加氢、脱氢、氢解等过程。Serp等[7]综述了CNTs在催化领域应用中的进展,认为其催化活性和选择性显示出令人鼓舞的前景。本文即采用乙二醇液相化学还原沉积法将少量Ru负载分散到CNTs上,制得一类Ru修饰碳纳米管复合材料,利用TEM、XRD 等技术对其进 行观测表征, 并以氨分解制氢作探针反应, 考察了 不同制备方法所得Ru /CNTs及添加碱/碱土金属 离子助剂对氨分解转化率的影响, 并讨论了CNTs 载体促进作用的本质。[英文文摘]A series of metallic Ru/CNTs were prepared using glycol reduction-deposition method. The results of TEM and XRD showed that metal Ru nanoparticles were quite uniform in shape and size(2~4 nm ) and well dispersed on the CNTs surface. The NH3-decom position conversion over Ru/CNTs catalyst prepared through ethylene glycol reduction-deposition was about 1.6 times as high as that of Ru/CNTs catalyst prepared by conventional incipientwetness method under the same reaction condition. The results demonstrated that NH3 decomposition over the Ru /CNTs catalyst using glycol reduction- deposition method with the Rux0-crystallite size at 3~4 nm displayed the highest reaction activity.While Rux0 particle size came dNH3 decom pos ition was m arked ly dropped. No ticeab ly, the promo ter o f K enhanced rem arkably catalytic activity of Ru /CNTs prepared using conven tiona l incipient w etness m ethod but few effect o f ones prepared using glycol reduction-deposition method.own to 2 nm and below, the conversion of NH3 decomposition was markedly dropped. Noticeably, the promoter of K enhanced remarkably catalytic activity of Ru/CNTs prepared using conventional incipient w etness m ethod but few effect of ones prepared using glycol reduction-deposition method.国家自然科学基金项目(20473063和20590364)资助; 校内青年科研基金(2009070)资

K-H3OFe3（SO4）2（OH）6铁矾的XRD研究

根据X射线衍射（XRD）分析发现：A Fe3（SO4）2（OH）6（A=K＋、H3O＋）系列铁钒的XRD数据十分相近,难以用XRD区别,需通过能谱（EDS）辅助分析,才能区分此类铁矾.另外,此类铁矾的003和107面网间距d随K＋含量增大而增大,且呈一元三次方程的关系;而033和220面网间距d随K＋含量增大而减小,呈一元二次方程的关系.对该现象从铁矾晶体结构方面进行解释：K＋、H3O＋离子位于较大空隙中,且沿着Z轴方向排列,当K＋、H3O＋离子之间相互替换时,会导致该铁矾晶体结构在Z轴方向有较明显的变化

K-H3OFe3（SO4）2（OH）6铁矾的XRD研究

根据X射线衍射（XRD）分析发现：A Fe3（SO4）2（OH）6（A=K＋、H3O＋）系列铁钒的XRD数据十分相近,难以用XRD区别,需通过能谱（EDS）辅助分析,才能区分此类铁矾.另外,此类铁矾的003和107面网间距d随K＋含量增大而增大,且呈一元三次方程的关系;而033和220面网间距d随K＋含量增大而减小,呈一元二次方程的关系.对该现象从铁矾晶体结构方面进行解释：K＋、H3O＋离子位于较大空隙中,且沿着Z轴方向排列,当K＋、H3O＋离子之间相互替换时,会导致该铁矾晶体结构在Z轴方向有较明显的变化

K-H_3OFe_3(SO_4)_2(OH)_6铁矾的XRD研究

根据X射线衍射(XRD)分析发现:A Fe3(SO4)2(OH)6(A=K+、H3O+)系列铁钒的XRD数据十分相近,难以用XRD区别,需通过能谱(EDS)辅助分析,才能区分此类铁矾。另外,此类铁矾的003和107面网间距d随K+含量增大而增大,且呈一元三次方程的关系;而033和220面网间距d随K+含量增大而减小,呈一元二次方程的关系。对该现象从铁矾晶体结构方面进行解释:K+、H3O+离子位于较大空隙中,且沿着Z轴方向排列,当K+、H3O+离子之间相互替换时,会导致该铁矾晶体结构在Z轴方向有较明显的变化

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors