钙钛矿型稀土复合氧化物催化活性研究进展

概述了近年来对钙钛矿型稀土复合氧化物催化活性研究的进展。研究发现,与其他催化剂相比,钙钛矿型稀土复合氧化物作为燃烧催化剂时,特别是对大气污染物降解具有较好的催化活性,而钙钛矿型稀土复合氧化物作为光催化剂时,对水体污染物降解方面具有很好的光催化作用,具有很大的应用价值。     

钙钛矿型LaFeO3和SrFeO3的光催化性能

采用柠檬酸法合成钙钛矿型复合氧化物LaFeO3和SrFeO3,并以其为光催化剂对不同水溶性染料进行光催化降解实验.结果表明:SrFeO3的光催化活性明显高于LaFeO3,这与A位离子(La3+,Sr2+)的电子构型的不同有关.     

A2BO4类钙钛矿型复合氧化物在催化领域的应用研究进展

概述了A₂BO₄类钙钛矿型复合氧化物的结构和性能，与ABO₃钙钛矿型氧化物进行了比较，简述了类钙钛矿型复合氧化物的制备方法和对复合氧化物的结构以及性能的影响，重点介绍了Ni系、Cu系和Co系等A₂BO₄型复合氧化物在尾气净化、NOx消除、氧化反应和甲烷氧化偶联等催化领域中的应用。     

钙钛矿SrNiO3光催化降解染料的研究

用柠檬酸络合法制备钙钛矿型复合氧化物SrNiO3,并以其为光催化剂对水溶性染料进行光催化降解实验.讨论了光催化反应时间、催化剂投加量、光照强度、pH值、以及外加氧化剂(H2O2)等因素对光催化活性的影响.实验结果表明:在催化剂投加量0.4 g,降解时间180min,pH值为2,光照强度200 W,H2O2的投加量5 mL时,大红染料的降解率可达99.47%.     

稀土钙钛矿型复合氧化物的制备及其在催化方面的研究进展

主要介绍了稀土钙钛矿型复合氧化物的结构及其主要制备方法,评述了各种制备方法的优劣.简述了目前国内外稀土钙钛矿型复合氧化物在催化方面的应用情况与研究进展,并对其前景进行了展望.     

介孔二氧化钛负载La_(1-x)Fe_xNiO_3催化剂光降解甲基橙的研究

本文采用溶胶凝胶法制备了粉体钙钛矿氧化物La_(1-x)Fe_xNiO_3(x=0.2,0.4,0.6,0.8)作为光催化剂,通过改变钙钛矿氧化物中掺杂元素Fe3+的比例,并将其负载到介孔二氧化钛上。通过对比钙钛矿型金属氧化物以及二氧化钛在自然光和紫外光下的催化降解甲基橙的降解率,发现介孔TiO_2负载La_(1-x)Fe_xNiO_3催化剂可有效地提高甲基橙的光降解率,相比于单独的钙钛矿型催化剂和二氧化钛催化剂,其光催化降解甲基橙的效果能提高40%。     

LaFeO_3的制备及对酸性红B降解性能的研究

采用柠檬酸溶胶凝胶法制备出复合氧化物LaFeO3,并以其为催化剂,以高压汞灯模拟太阳光,对染料酸性红B进行降解。实验考查了反应时间、催化剂用量、起始浓度对降解率的影响,同时用XRD、TEM等手段对产品进行了表征。研究结果表明:所制备的催化剂LaFeO3为纳米级钙钛矿型复合氧化物,对染料酸性红B有良好的催化降解效果。50mL、10mg/L酸性红B溶液用0.125g催化剂降解70min降解率达到94.5%。     

钙钛矿型复合氧化物的制备及应用

综述了近年来国内外钙钛矿型复合氧化物的制备方法;分析了钙钛矿型复合氧化物的应用前景.     

钙钛矿型复合氧化物对甲烷的部分氧化及在混合太阳能氧化还原过程的应用

利用固相法合成了3种钙钛矿型复合氧化物Fe2O3-CaTixM1?xO3,研究了其结构、晶型和氧化还原活性。在固定床反应器中考察了该氧化物对两步法甲烷催化氧化制合成气及水分解制氢的活性及选择性。X射线衍射结果表明3种钙钛型复合氧化物均由正交晶系钙钛矿相和赤铁矿相组成。3种钙钛矿复合氧化物对甲烷的氧化活性顺序为Fe2O3-CaTi0.85Ni0.15O3Fe2O3-CaTi0.85Co0.15O3Fe2O3-CaTi0.85Fe0.15O3。固定床反应结果表明,以Fe2O3-CaTi0.85Ni0.15O3为氧载体催化剂,CH4转化率可达96%,CO和H2产率达71%,同时水分解反应的转化率为40%。利用Aspen Plus?对Fe2O3-CaTi0.85Ni0.15O3在混合太阳能氧化还原过程的效率及合成油和H2产率进行了模拟。模拟计算结果证明基于复合氧化物的混合太阳能氧化还原过程可以有效提高CH4利用率。     

钙钛矿氧化物的制备及其在环境保护中的应用

由于其良好结构稳定性和传递O2-和电子性能,钙钛矿氧化物可作为具有高效催化活性的功能性催化材料,可广泛应用于气相、液相和固相污染物的控制及处理过程,实现环境友好型化工过程.本文综述了钙钛矿氧化物制备方法、表征手段及对其性能影响的关键调控因素,重点介绍了钙钛矿氧化物在NOx污染物分解、挥发性有机化合物(VOCs)催化燃烧、烟灰催化转化、水中有机染料氧化降解方面的应用.     

Virtual Screening of Small Drug‐Like Compounds Stimulating the Enzymatic Activity of Kallikrein‐Related Peptidase 3 (KLK3)

Kallikrein‐related peptidase 3 (KLK3) is a prostatic serine protease shown to possess antiangiogenic properties which are exerted via its proteolytic activity. The antiangiogenic effect indicates that KLK3 may slow down the growth of prostate cancer; this makes it an interesting target for new therapies for prostate cancer. In this work, new drug‐like compounds were discovered that stimulate the proteolytic activity of KLK3. The compounds were identified using 2D similarity search and 3D pharmacophore‐based virtual screening, and their ability to stimulate KLK3 was verified by enzymatic activity assays. The effect of the molecules alone was modest, but in synergy with a cyclic peptide the most potent molecule was found to stimulate KLK3 activity significantly: up to 351 % of the activity of KLK3. This demonstrates that small drug‐like compounds can be beneficial tools in studying the antiangiogenic properties of KLK3.     

Effect of serum lipoproteins of bile obstructed rats on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in perfused rat liver

Total lipoproteins as well as fractionated VLDL+LDL and HDL from fasted control rats and bileligated rats were tested in liver perfusion for their effect on 3-hydroxy-3-methylglutaryl CoA reductase to increase 3-hydroxy-3-methylglutaryl CoA reductase activity than that of the control total lipoproteins. When the fractionated lipoproteins were tested from fasted control rats, it was found that the major stimulating activity was in the HDL fraction with minor activity in the VLDL+LDL fraction. When these plasma components isolated from fasted bile-ligated rats were tested, it was found that the major activity had shifted to the VLDL+LDL fraction with the HDL having only a minor stimulatory role. The possible mechanism of action of the abnormal lipoproteins associated with bile obstruction in regulating 3-hydroxy-3-methylglutaryl CoA reductase activity is discussed.     

Effect of buffer constituents on rat liver 3-hydroxy-3-methyl glutaryl coenzyme A reductase

Rat liver microsomes prepared in Tris buffer exhibited 3 to 10 times higher 3-hydroxy-3-methyl glutaryl CoA reductase specific activity than microsomes prepared with potassium phosphate buffer. This higher activity was observed in rats killed during mid-light cycle, but microsomes from rats killed during mid-dark cycle showed no significant difference in enzyme activity between buffers. When microsomes prepared in the 2 different buffers were preincubated with ATP and MG⁺⁺, enzyme activity was inhibited to the same extent. The cytosol fraction in each of the 2 different buffer preparations possessed similar phosphatase activity. The higher 3-hydroxy-3-methyl reductase activity in Tris buffer, therefore, does not appear to be due to differences in phosphorylation or dephosphorylation activity.     

甲苯侧链烷基化催化剂的评选及反应性能研究

用脉冲微反技术对甲醇-甲苯侧链烷基化反应催化剂进行了评价,发现在所用几种催化剂中,X型沸石的活性和选择性最佳。随着交换的碱金属离子半径的增大,活性和选择性均有增大趋势。用H3BO3 和CaO对KX沸石进行改性后可显著提高侧链烷基化选择性。将浸渍H3BO3的KX和碱土化合物改性的KZSM-混合而成的双组分催化剂具有良好的活性和选择性。     

多粘类芽孢杆菌极端嗜热多肽的纯化及性质研究

用加热法从多粘类芽孢杆菌(Paenibacillus polymyxa)LM–3菌株的发酵液中纯化得到2个极端嗜热多肽。平板拮抗实验表明,5μL纯化多肽对稻瘟病菌(Magnaporthe grisea)抑菌率达89.6%。SDS–PAGE电泳显示纯化多肽分子量介于6000～7000u之间。多肽复性后,其中之一对稻瘟病菌表现出强的拮抗活性,命名为APPLM3(Antagonism Polypeptide from Paenibacillus polymyxa LM–3);另一个则无此活性,命名为PPLM3(Polypeptide from Paenibacillus polymyxaLM–3)。APPLM3经氨基酸测序,获得了其N–末端5个氨基酸序列(H2N–ANDPR);以该序列为靶序列在NCBI上进行相似性检索,发现其可能与3个假设蛋白(或推导蛋白)相关。APPLM3为首次报道的兼具极端嗜热性和稻瘟病菌拮抗活性的小分子多肽。     

新型熊果酸喹啉衍生物抗肿瘤活性研究

原料为五环三萜类天然产物熊果酸,合成新型熊果酸喹啉衍生物。使用元素分析法、ESIMS、13C NMR等,分析1,3,4-噁二唑衍生物4a-4f,以及熊果酸喹啉酰肼衍生物3a-3f。采用MTT法,对4a-4f、3a-3f进行测试,分析对三种肿瘤细胞株的增殖抑制活性。结果显示,对三种肿瘤细胞株,包括SMMC-77213、HeL、MDA-MB-231,3a-3c都有明显的抑制活性。比对照依托泊苷更强,对SMMC-77213、HeL、MDA-MB-231的IC50值,分别是17.49～19.43μmol/L、0.84～1.19μμmol/L、1.17～1.85μμmol/L。根据抗肿瘤活性结果显示,喹啉基引入熊果酸分子中,羧基修饰为1,3,4-噁二唑基、酰肼基,抗肿瘤活性能够明显增强,酰肼的衍生物为侧链,相比噁二唑的衍生物活性更佳。因此,能够进一步优化熊果酸结构,提升抗肿瘤活性。     

Effects of bile salts on rat hepatic acyl CoA:Cholesterol acyltransferase

Acyl CoA:cholesterol acyltransferase (EC2.3.1.26, ACAT), responsible for intracellular esterification of cholesterol, may play an important role in cholesterol trafficking within the cell, and thus, in maintenance of cellular cholesterol homeostasis. Bile acids are potential regulators of cholesterol trafficking in the liver. Therefore, the effect of bile salts on hepatic ACAT activity was studied in the perfused rat liver. ACAT activity was increased after liver perfusion with either taurocholate or taurochenodeoxycholate. However, addition of these bile salts at physiological concentrationsin vitro had little effect on microsomal ACAT activity. The increase in hepatic ACAT activity due to perfusion with bile salts was accompanied by reduced accumulation of very low density lipoprotein cholesterol in the perfusate, but there was no effect on 3-hydroxy-3-methylglutaryl-CoA reductase activity. Hepatic ACAT activity was decreased after bile diversion for four hours in the intact animal. This treatment had no statistically significant effect on 3-hydroxy-3-methylglutaryl-CoA reductase activity. These data suggest that bile salts induce changes in hepatic compartmentation and traffic of cholesterol within the hepatocyte accompanied by response of ACAT activity to maintain cellular cholesterol homeostasis.     

Effects of the pretreatment of Cu-Y zeolite catalysts on the reduction of nitric oxide with ammonia

Experiments were conducted to study the effects of pretreating Cu-Y zeolite catalysts on the reduction of nitric oxide with ammonia. Changing the oxidation state and environment of the copper in Cu-Y changed the optimal reaction temperature of the NO---NH₃ reaction and the activity of this catalyst. At the optimal temperature, the activity of Cu-Y after dehydration was higher than that of hydrated Cu-Y. In addition, at the optimal temperature, the activity of Cu-Y after the NO---NH₃ reaction followed by oxidation or ammonia pretreatment followed by oxidation was higher than that of dehydrated Cu-Y. The activity of Cu-Y at the optimal temperature was decreased by reduction at higher temperature but increased by reduction at lower temperature. Furthermore, the activity of Cu-Y increased as the copper loading was increased. The optimal reaction temperatures of the NO---NH₃ reaction over various pretreated Cu-Y catalysts were 106, 126, 220 and 300°C, respectively.     

纳米粒子Al2O3 催化剂在制备n-DOP增塑剂反应中的催化活性

用改进了的溶胶2凝胶法新工艺在不同条件下制备出不同结构的纳米粒子A l₂O₃ 催化剂。采用在纳米A l₂O₃ 催化作用下苯酐与正辛醇反应生成n-DOP 增塑剂的方法考察了不同纳米A l₂O₃ 的催化活性。结果表明, 由于制备条件对纳米A l₂O₃ 前驱体组成结构的影响, 使制得的纳米A l₂O₃ 催化性能各异。以C 型纳米G₂A l₂O₃ 的催化活性较高。B 型纳米C₂H₂A l₂O₃ 催化剂具有较高的比活性。反应转化率随温度升高而逐渐增大, 而纳米A l₂O₃ 催化活性在低温时也随温度升高而增大, 高温时则不明显, 相反, 随反应时间增长, 催化活性急剧下降。     

Pd/Ce基催化剂催化氧化氯苯的性能

采用等体积浸渍法制备Pd/Al₂O₃系列催化剂,考察不同Pd负载量对催化剂催化氯苯活性的影响,结果表明0.75%Pd/Al₂O₃催化剂活性最优,采用BET、H₂-TPR、SEM等对催化剂进行表征分析,表明添加Ce后氧化能力增强,催化氧化效率提高。对催化产物进行分析,使用离子色谱分析了无机Cl^-生成情况及其选择性,使用GC-MS定性分析了有机副产物,发现350℃时有少量苯生成。同时考察了焙烧温度、氯苯浓度、空速对催化活性的影响,结果表明焙烧温度过高或过低都会影响催化剂的活性,在550℃焙烧的催化剂活性更优,400℃时氯苯转化率为96%;氯苯入口处质量浓度在1500～6000mg/m³时,浓度升高,催化氯苯活性降低;空速在15000～30000h^-1时,空速对氯苯催化活性影响不大,但继续提高空速会明显降低催化活性。