排序方式: 共有41条查询结果,搜索用时 15 毫秒
31.
32.
Preparation and Physicochemical Characterization of La1-xCexCoO3+δ Perovskite Catalyst and Its Methane Catalytic Combustion 总被引:2,自引:0,他引:2
Perovskite oxide LaCoO3 methane catalytic material was synthesized with citric acid complexation and bubbling method.The effect of doped cerium was studied on the series of La1-xCexCoO3 δ materials by means of BET,XRD and SEM techniques.Their catalytic behaviors were studied with methane catalytic complete combustion as probe reaction.The results show that doped cerium has great effect on crystal phase formation.When doped cerium is less than 0.3 (molar ratio),the crystal phase of oxide has little changed.When doped cerium is up to 0.5,Co3O4 phase is obviously discovered and the perfectibility of LaCoO3 perovskite crystal phase is deteriorated.When x is over 0.7,perovskite crystal phase is weakened or completely disappeared.Considering the crystal phase of oxides,the optimum doped cerium is about 0.3.The perovskite oxides can be formed at a low calcinations temperature of 700 ℃.When x is 0.3,the highest catalytic activity of T10% (390 ℃) and T90% (603 ℃) is obtained on the series of La1-xCexCoO3 δ materials calcined at 800 ℃. 相似文献
33.
34.
力化学铝土矿溶出的作用 总被引:3,自引:0,他引:3
力化学方法处理铝土矿,可明显改善其溶出性能,对国内2种有代表性的铝土矿;广西平果矿和山西普铝矿采用该法处理,使矿石中的一水硬铝石结构发生变化,从而降低了溶出温度及溶出用碱液浓度,并提高了溶出速率。对力化学引起的反应性能变化及其内在原因进行了探讨。据此确认该法对我国氧化铝工业节能降耗、提高经济效益具有实际意义。 相似文献
35.
Thorium (Th) stripping behavior from HEH/EHP (2-(ethylhexyl) phosphoric acid mono-2-ethylhexyl ester) with H2SO4, HCl and HNO3 were investigated. The results indicated that H2SO4 was the most effective stripping reagent compared with HCl and HNO3. Selecting H2SO4 as the stripping reagent, the effect of phase ratio, acidity, H2SO4 amount, HEH/EHP concentration and Th loading in HEH/EHP on Th stripping were systematically investigated. As a result, the optimum stripping conditions of Th(IV) were obtained as the concentration of H2SO4 solution was 3.50 mol/L, phase ratio was 4:1. Low HEH/EHP concentration was benefit for Th stripping. Based on the results, pilot test for new Bastnaesite treatment process was carried out and the recovery of Ce, F and Th were more than 99%, 98% and 95% separately. 相似文献
36.
稀土冶炼废水处理技术发展现状 总被引:5,自引:0,他引:5
我国稀土矿物品种较多,冶炼工艺比较复杂,生产过程产生大量废水,每生产1 t稀土氧化物产生60~100 t废水,主要包括酸性含氟废水,碱性含氟废水,以及稀土萃取分离皂化有机相和碳酸氢铵沉淀稀土过程产生的氨氮废水,其中氨氮废水的污染问题尤为突出,废水中氨氮超标几十倍甚至数百倍,给环境带来了严重的污染。本文对目前工业上各种稀土冶炼废水的防治方法进行了调研,根据稀土冶炼各个环节产生的废水特性,以及工艺成熟度、经济合理性、技术先进实用性进行总结评价,对各种废水防治方法进行优选。建议萃取分离过程采用非皂化或钙皂化工艺代替氨皂化工艺,碳酸钠代替碳酸氢铵沉淀稀土,从源头消除氨氮废水的污染;酸性含氟废水采用酸回收净化工艺回收硫酸和氟盐,高浓度氨氮废水采用蒸发浓缩法回收处理,低浓度氨氮废水采用膜法、折点氯化法等方法处理,总体实现达标排放。 相似文献
37.
采用共沉淀水热联合法制备了大比表面铈锆复合氧化物材料,在较低焙烧温度400℃下形成了稳定的晶相结构,500℃焙烧新鲜比表面达135.44 m2/g,900℃、6 h老化后比表面仍维持44.07 m2/g。采用沉淀陈化工艺,并掺杂改性,得到的铈锆复合氧化物,稳定性更高,经950℃、2 h老化后,最高比表面可达59.62 m2/g。活性氧化铝与铈锆复合氧化物有协同作用,二者复合得到了更高性能的氧化物材料,新鲜比表面为188.92 m2/g,经950℃、4 h老化后,比表面为71.64 m2/g,经1 050℃、4 h老化后,比表面为58.10 m2/g。对所得铈锆材料进行了X射线衍射、吸脱附表征,并负载钯贵金属制得催化材料,以甲烷完全催化燃烧为探针反应,研究了铈锆复合氧化物材料的甲烷燃烧催化性质。结果表明,铈锆复合氧化物材料是很好的燃烧催化剂二载材料,负载钯催化剂具有较高催化活性,起燃温度降低至352℃。 相似文献
38.
39.
用碳酸氢铵从硝酸铈溶液中沉淀制备了超细CeO2粉体,研究了沉淀工艺条件对制备CeO2的一次粒径、团聚粒径以及粉体团聚性的影响.研究表明形成的碳酸铈胶状沉淀物需要在高温下陈化足够长的时间才能制备出一次粒径小,分散性好的CeO2产品,否则将形成大的团聚体.当碳酸氢铵与硝酸铈的摩尔比为31左右、沉淀温度为50℃左右时制备的CeO2具有小的一次粒径,而且产品的分散性好.适当地增大加料速度和初始料液的pH值有利于减小CeO2的一次粒径和团聚性. 相似文献
40.
从混合酸性磷类负载有机相中反萃稀土的研究 总被引:2,自引:0,他引:2
对负载Sm,Gd,Y的HDEHP和HEH/EHP混合萃取体系进行了反萃性能研究,测定了不同酸度下的累积反萃率,表明反萃率随混合体系中HEH/EHP摩尔比的增加而增大,对于Sm,Gd,Y来说,Sm在有机相中最易反萃,Y最难反萃.同时比较了相同酸度的HCl,HNO3及H2SO4对同一负载有机相的反萃性能,反萃能力为HCl>HNO3>H2SO4.采用HCl对负载Y的HDEHP和HEH/EHP及HDEHP和Cyanex272两种混合萃取体系的反萃性能进行了比较,表明后者具有更优异的反萃性能. 相似文献