首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 265 毫秒
1.
以硝酸锂(锰)、醋酸锂(锰)、尿素和柠檬酸为原料,利用液相燃烧合成方法研究了两种不同酸根盐体系以及燃料尿素用量和柠檬酸对燃烧合成尖晶石型LiMn2O4的影响,并用氧化还原滴定法测定产物中Mn的平均化合价作为合成产物为LiMn2O4的辅证依据。XRD分析表明,液相燃烧合成可制备得尖晶石型LiMn2O4物质,锂和锰的醋酸盐体系燃烧合成LiMn2O4比硝酸盐体系好,燃料尿素比柠檬酸好;醋酸盐和尿素的燃烧体系可得纯相LiMn2O4产物,硝酸盐和尿素的燃烧体系中含有较多Mn2O3,但随尿素量增多,杂相Mn2O3的含量减少;产物LiMn2O4中Mn的价态为+3.5左右,与LiMn2O4中Mn的标准价态相同。  相似文献   

2.
用Cu-ZnO/Al2O3催化仲丁醇制备甲乙酮。研究了催化剂的焙烧温度和焙烧时间、仲丁醇脱氢反应的温度和压力以及仲丁醇的流量对仲丁醇转化率和甲乙酮选择性的影响。结果表明,催化剂的焙烧温度为300-400℃,焙烧时间为6h,脱氢反应的温度为300℃,压力为0.2Mpa,仲丁醇的流量为140mL/h时,仲丁醇的转化率和甲乙酮的选择性较好。  相似文献   

3.
以有机物前驱体法制备铝酸盐尖晶石MAl2O4(M为Cu,Zn),采用X-射线衍射、透射电镜等方法对试样进行表征.结果表明:700℃焙烧得ZnAl2O4,800℃焙烧得到CuAlz04和微量Cu0.在以甲基橙为降解物和100W汞灯辐照2h的光催化实验中,700℃焙烧ZnAl2O4粉体对甲基橙的脱色率为89.4%;而800℃的CuAl2O4对甲基橙的脱色率可以达到96.7%.  相似文献   

4.
以廉价的氢氧化铝、氢氧化钠和硫酸铵为主要原料,成功制备了SO4^2-/y-Al2O3,固体超强酸催化剂。将其用于乙酸正丁酯合成反应,并探讨了催化剂制备条件(浸渍液浓度、焙烧温度和焙烧时间)对酯化率的影响。结果表明:SO4^2-/y-Al2O3固体超强酸催化剂的最佳制备条件为浸渍液浓度1.2mol·L^-1,焙烧温度600℃,焙烧时间3h。  相似文献   

5.
制备了固体超强酸催化剂SO2-4/Fe2O3,并依照傅-克烷基化反应的原理,以对叔丁基苯酚的合成为探针反应,考察了硫酸浸渍浓度、焙烧温度等制备条件对SO2-4/Fe2O3催化活性的影响.实验表明:制备催化剂的适宜条件为硫酸的浸渍浓度为0.5 mol·L-1,焙烧温度为550℃,活化时间4 h.利用优化条件下制备的催化剂SO2-4/Fe2O3催化甲基叔丁基醚与苯酚的烷基化反应合成对叔丁基苯酚,在苯酚与甲基叔丁基醚的投料摩尔比为1:2.0,催化剂的用量占反应物总投料质量的4%,反应时间为3 h,反应温度为90℃下,烷基化反应收率为80.8%.  相似文献   

6.
制备了固体超强酸催化剂SO2-4/Fe2O3,并依照傅-克烷基化反应的原理,以对叔丁基苯酚的合成为探针反应,考察了硫酸浸渍浓度、焙烧温度等制备条件对SO2-4/Fe2O3催化活性的影响.实验表明:制备催化剂的适宜条件为硫酸的浸渍浓度为0.5 mol·L-1,焙烧温度为550℃,活化时间4 h.利用优化条件下制备的催化剂SO2-4/Fe2O3催化甲基叔丁基醚与苯酚的烷基化反应合成对叔丁基苯酚,在苯酚与甲基叔丁基醚的投料摩尔比为1:2.0,催化剂的用量占反应物总投料质量的4%,反应时间为3 h,反应温度为90℃下,烷基化反应收率为80.8%.  相似文献   

7.
以Mo-K2O-CuO/Fe2O3催化乙苯脱氢制苯乙烯,考察了催化荆的制备条件和反应过程条件对乙苯脱氢反应活性和苯乙烯选择性的影响.结果表明,催化荆的焙烧温度为800℃,焙烧时间为4h,苯乙烯脱氢反应的温度为580~600℃,压力为0.1Mpa,以及乙苯液空速为0.6h^-1水蒸气与乙苯的质量比为1.6时,乙苯脱氢反应活性和苯乙烯选择性最好,  相似文献   

8.
以廉价的氢氧化铝、氢氧化钠和硫酸铵为主要原料,成功制备了SO42-/γ-Al2O3固体超强酸催化剂.将其用于乙酸正丁酯合成反应,并探讨了催化剂制备条件(浸渍液浓度、焙烧温度和焙烧时间)对酯化率的影响.结果表明:SO42-/γ-Al2O3固体超强酸催化剂的最佳制备条件为浸渍液浓度1.2 mol·L-1,焙烧温度600℃,焙烧时间3h.  相似文献   

9.
以NH4VO3为原料,(NH4)2S2O8为浸渍液,添加少量稀土Ce^4+,用沉淀-浸渍法制备出新型S2O8^2-/V2O5-CeO2固体超强酸催化剂,以合成乙酸苄酯作为探针反应考察不同条件下制备的超强酸的催化活性。研究发现,当加入CeO2量为催化剂总量的1.0%,焙烧温度为500℃,浸渍液浓度为1.5mol/L,焙烧时间为3h时,催化剂的活性最好。  相似文献   

10.
采用浸渍法制备SO_4~(2-)/ZrO_2-SiO_2固体超强酸,并以廉价的1,4-丁二醇和工业废气在吸收过程中产生的溴化氢为原料,以合成的SO_4~(2-)/ZrO_2-SiO_2固体超强酸为催化剂合成用途广泛的1,4-二溴丁烷.采用正交试验研究了SO_4~(2-)/ZrO_2-SiO_2固体超强酸制备过程中的复配比、焙烧温度、焙烧时间、硫酸浓度等因素对其催化性能的影响,以1,4-二溴丁烷的收率为考核指标,确定了SO_4~(2-)/ZrO_2-SiO_2固体超强酸的最佳制备工艺.结果表明:当n(Zr)∶n(Si)为1∶4、陈化时间12 h、预焙烧温度200℃、焙烧温度550℃、焙烧时间3 h、H_2SO_4浓度1.00 mol/L、m(前驱体)∶V(H_2SO_4)=1∶10时制备的固体超强酸的催化性能最佳.  相似文献   

11.
The influence of calcination temperature on TiO2 nanotubes' catalysis for TiO2/UV/O3 was investigated. TiO2 nanotubes (TNTs) were prepared via the sol-gel method and calcined at 300-700℃, which were labeled as TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700, respectively. TNTs were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is found that TNTs calcined at 400 ℃ showed the best thermal stability. When the calcination temperature increased from 400 ℃ to 700 ℃, the special structure of tubes was destroyed and gradually converted into nanorods and/or particles. The transformation from anatase to rutile occurred at 600 ℃, and the rutile phase was enhanced when the calcination temperature was increased to over 600 ℃. The calcina-tion temperature's influence on TNTs' adsorption activity for chemical oxygen demand (COD) and catalytic activity for TiO2/UV/O3 was investigated in landfill leachate solution. In landfill leachate solution, the adsorption activity of COD decreased in the reduced order of TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700. In photocatalytic ozonation, TNTs-400 showed the best catalytic activity while TNTs-700 exhibited the worst. In other three processes, the COD removal of TNTs-300/UV/O3 was higher than those of TNTs-500/UV/O3 and TNTs-600/UV/O3 in the first 20 min, and then became close to those of the latter two in the following 40 min. Compared with TNTs-300 and TNTs-400, TNTs-600 had the best anti-fouling activity, while TNTs-500 and TNTs-700 had lower anti-fouling activity than the former three. In photocatalytic ozonation, the calcination temperature of 400 ℃ was appropriate when TNTs were obtained at the synthesis temperature of 105 ℃.  相似文献   

12.
利用N2物理吸附、XRD和空气热重对Cu-ZnO/Al2O3甘油加氢催化剂在制备过程中物相结构的变化进行了系统的研究.研究结果表明,干燥后催化剂主要由Cu2Zn4Al2(OH)16CO3 4H2O和Cu2(OH)2CO3物相组成,经过600℃焙烧4 h后,催化剂在沉淀过程中生成的Cu2Zn4Al2(OH)16CO3 4H2O和Cu2(OH)2CO3全部分解为CuO.在500℃催化剂具有最大的比表面积(79 m^2/g)和孔容(0.36 cm^3/g).  相似文献   

13.
采用固相反应法合成了中温固体氧化物燃料电池阴极材料BaCo0.7Fe0.2Nb0.1O5+δ(BCFN).结果表明:BCFN与电解质La0.9Sr0.1Ga0.8Mg0.2O2.85(LSGM)在10000C烧结5h没有生成其他杂相,表明其与LSGM电解质在高温时具有很好的化学兼容性.BCFN在700℃时极化电阻仅为0.128Ωcm2.在800℃时,BCFN的过电位为49mV时的电流密度是46mAcm-2.  相似文献   

14.
采用溶胶-凝胶法制备不同粒径的La缺位La0.9MnO3钙钛矿氧化物.用X射线衍射、扫描电子显微镜、振动样品磁强计对材料的晶体结构、微结构、磁性和磁热效应进行了研究.结果表明,不同温度下退火(700oC~1100oC)的样品均具有菱形钙钛矿结构.退火温度从700oC增加到1100oC,样品的平均晶粒大小从25 nm增加到1000 nm.随着晶粒大小的增加,材料在低温的饱和磁化强度逐渐增强,铁磁到顺磁的相变变得陡峭,从而使材料的磁熵变逐渐增加.当材料的晶粒尺寸大于500 nm时,材料的磁熵变趋于稳定(-2.7 J/kg·K).  相似文献   

15.
采用等离子体增强化学气相沉积技术制备了硼掺杂氢化非晶硅薄膜,然后经过不同温度的热退火处理,获得硼掺杂纳米硅薄膜.结果表明,退火温度为700℃时,样品中开始有纳米晶形成,随着退火温度的增加,在1000℃时,薄膜的晶化率达到77%,晶粒大小为3.9nm.退火温度低于600℃时,光学带隙随着退火温度的升高而变窄,高于600℃...  相似文献   

16.
采用共沉淀法合成了锂离子电池层状LiNi1/3Co1/3Mn1/3O2正极材料。采用TG/SDTA、XRD和SEM对LiNi1/3Co1/3Mn1/3O2正极材料的成分、结构和形貌进行了表征。结果表明,在900℃下煅烧15h制得的材料结晶程度最佳,样品具有最大I(003)/I(104)强比值,层状结构特征最为突出。从单个颗粒来看,样品表面光滑,界面清晰,粒子呈类球状,粒径大约在0.5μm左右,分散较为均匀。另外,添加剂对粒子形貌具有一定的影响。  相似文献   

17.
The influence of calcination temperature on TiO2 nanotubes' catalysis for TiO2/UV/03 was investigated. TiO2 nanotubes (TNTs) were prepared via the sol-gel method and calcined at 300--700 ℃, which were labeled as TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700, respectively. TNTs were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is found that TNTs calcined at 400 ℃ showed the best thermal stability. When the calcination temperature increased from 400 ℃ to 700 ℃, the special structure of tubes was destroyed and gradually converted into nanorods and/or particles. The transformation from anatase to rutile occurred at 600 ℃, and the rutile phase was enhanced when the calcination temperature was increased to over 600 ℃. The calcina- tion temperature's influence on TNTs' adsorption activity for for TiO2/UV/O3 was investigated in landfill leachate solution chemical oxygen demand (COD) and catalytic activity In landfill leachate solution, the adsorption activity of COD decreased in the reduced order of TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700. In photocatalytic ozonation, TNTs-400 showed the best catalytic activity while TNTs-700 exhibited the worst. In other three processes, the COD removal of TNTs-300/UV/O3 was higher than those of TNTs-500/UV/O3 and TNTs-600/UV/O3 in the first 20 rain, and then became close to those of the latter two in the following 40 rain. Compared with TNTs-300 and TNTs- 400, TNTs-600 had the best anti-fouling activity, while TNTs-500 and TNTs-700 had lower anti-fouling activity than the former three. In photocatalytic ozonation, the calcination temperature of 400 ℃ was appropriate when TNTs were obtained at the synthesis temperature of 105 ℃.  相似文献   

18.
采用包渗法在钼表面原位制备了(Mo,W)Si2-Si3N4复合涂层,考察了其在大气中于500℃和600℃等温循环的氧化性能,利用XRD和SEM等研究了其组织形貌.结果表明:(Mo,W) Si2-Si3N4涂层具有良好的低温抗氧化性,其在空气中500℃和600℃氧化480 h的氧化速率分别为0.0145 g/(m2·h)和0.0191g/ (m2·h),归因于涂层氧化表面形成了致密的SiO2膜.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号