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研究了分子筛担载FeSO4催化剂在SCR脱硝反应中的催化性能和反应机理。实验结果表明,在同等工况下分子筛担载FeSO4后的催化剂具有更好的物理结构,与纯FeSO4相比脱硝率可提高将近20%。经Mossbauer谱分析,催化剂制备过程中Fe2+转化为Fe3+,其具体存在形式为Fe (OH)SO4与Fe2O(SO4)2,前者催化脱硝效果优于后者。原位红外分析结果表明,吸附在分子筛担载催化剂表面的氨与气相中的NO反应,Fe离子是吸附及发生催化氧化还原反应的活性中心。与钒、钛系相似文献
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探讨了一种新型季铵盐——四丁基氯化铵的水合物作为蓄冷工质的可行性,对其蓄冷特性进行了实验研究:研究了溶液浓度、循环次数及添加成核剂硼砂对四丁基氯化铵水合物的生长特性的影响。实验结果表明:浓度为40%的TBAC溶液相变过程相对稳定,更适合空调蓄冷工况;添加成核剂硼砂使TBAC溶液的相变温度降低了2℃,结晶过冷度减小2℃;经过多次重复水合反应后,溶液在结晶过程中的过冷度减小了1.5℃,相变温度无变化。利用DSC测试得到四丁基氯化铵水合物相变温度为10.41℃,相变潜热为197.707J.g-1。 相似文献
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γ-谷氨酰转肽酶(GGT)在临床诊断和生物催化方面具有重要的应用价值。本文以介孔氧化钛晶须为载体进行GGT的固定化,考察了载体结构特性、吸附时间和给酶量对固定化效果的影响,并对固定化酶的催化特性及其稳定性进行了研究。结果显示,以最可几孔径为30 nm的介孔TiO2为载体,载体载酶量可达5.07mg·g-1。在给酶量为18.99 U·g-1时,经室温吸附2.5 h,固定化酶活性回收率可达73.05%。固定化酶的pH稳定性和热稳定性均显著优于游离酶,在4℃下保温贮藏60 d、转化22个批次后,固定化酶活力仍可保持初始值的71.30%。经测定,游离酶和固定化酶的米氏常数Km分别为0.79 mmol·L-1和1.05 mmol·L-1,酰基化反应活化能分别为13.59 kJ·mol-1和15.42 kJ·mol-1;固定化GGT的失活反应活化能Ed为92.80 kJ·mol-1,相比于游离酶(49.61 kJ·mol-1)有明显的增加。 相似文献
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采用SiO2、MgCl2以及苯乙烯-丙烯酸共聚物(PSA)合成了SiO2/MgCl2.xBu(OH)2/PSA无机/有机复合载体并负载TiCl4,得到具有SiO2无机支撑层、MgCl2.xBu(OH)2加合物以及PSA有机载体3种化学环境的SiO2/MgCl2.xBu(OH)2/PSA/TiCl4复合载体负载催化剂。研究了复合载体组成对催化剂的载钛量、形貌以及乙烯聚合行为的影响。当PSA存在时,催化剂的载钛量明显降低。乙烯/1-己烯共聚的反应动力学结果表明,与SiO2/MgCl2.xBu(OH)2/TiCl4相比,无机/有机复合载体负载催化剂的动力学曲线具有一段较长的受扩散控制的诱导期,并且随着PSA质量分数的增加,诱导期延长,动力学曲线由衰减型转变为上升-稳定型。由于复合载体具有多种化学环境,使得负载催化剂活性中心种类增多,共聚性能提高,聚乙烯产品分子量分布变宽,熔流比显著提高。根据聚乙烯树脂的扫描电镜照片,探讨了复合载体负载催化剂在聚乙烯生长过程中的破碎机理。 相似文献
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The decomposition of 2,4-dichlorophenoxyacetic acid in aqueous solutions has bsen studied using ozone and ultraviolet radiation at different pH, ozone production, and initial concentration of pesticide. A mathematical model which incorporates the rate of mass transfer of ozone, the oxidation kinetics of 2,4-D and the kinetics of formation and oxidation of the intermediates was used. A global rate constant was calculated and an empirical equation which correlated that constant with ozone production, initial concentration of 2,4-D and pH at the same temperature was determined. 相似文献
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Rate constants for the degradation of five herbicides (Mecoprop, MCPA, 2,4-D, Simazine and Atrazine) by ozone were determined in the laboratory under controlled conditions at both acidic and neutral pH using a competition kinetic method. The order of herbicide degradation rate was found to be as follows: Mecoprop > MCPA > 2,4-D > Simazine > Atrazine, both at pH 2 and pH 7.5. The half-life times for herbicide removal at pH 7.5 and in the presence of bicarbonate ions are, respectively, 25.9; 27.5; 39.5; 66.6 and 94.2 minutes for Mecoprop, MCPA, 2,4-D, Simazine and Atrazine at a dissolved ozone concentration of 10 μM. The kinetics of ozone consumption for the three phenoxyalkyl acid derivatives were investigated at pH 2. The study has demonstrated that at neutral pH the initial concentration ratio of two herbicides in solution together did not affect their relative degradation rate. 相似文献
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采用停流光谱仪研究了异丙醇在T=298K和pH=3~11范围内O3 / H2O2复合氧化的反应动力学.结果表明异丙醇的O3 / H2O2复合氧化反应动力学随反应体系的pH值不同而不同.在酸性和中性条件下,反应相对于O3浓度、异丙醇浓度都为1级;在碱性条件下,异丙醇较容易被O3/H2O2复合氧化降解,总反应级数为2级,相对于O3浓度、异丙醇浓度和H2O2浓度分别为1级、0级和1级,可见异丙醇的降解速率与它的浓度无关.在T=298K,当pH值从9增大到11, 反应速率常数从3486.1(mol·L-1)-1·s-1增大到38239.2(mol·L-1)-1·s-1. 表明在酸性条件下,异丙醇的O3/H2O2复合氧化是O3分子直接攻击异丙醇的反应占主导;在碱性条件下,自由基型反应占主导. 相似文献
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苯酚的O_3/H_2O_2化学氧化反应动力学研究 总被引:2,自引:0,他引:2
应用 Stopped- flow光谱仪研究苯酚在 2 88~ 30 8K和 p H=3.2~ 9.8的 O3 / H2 O2 氧化反应动力学。通过实验及分析认为 :在不同酸度的实验条件下苯酚 O3 / H2 O2 氧化降解的途径及动力学不同。在酸性及弱酸性(p H=6 .5 )下苯酚 O3 / H2 O2 氧化反应机理是苯酚直接为 O3 氧化 ,在碱性 (p H=9.8)时为自由基机理 相似文献
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引言2,4-二氯苯氧乙酸(2,4-D,又名2,4-滴)是一种广泛使用的除草剂[1],应用历史较长,是我国主要的除草剂品种之一,用量也比较大。2,4-D属于苯氧羧酸类除草剂的一种,可有效去除阔叶杂草,目前仍广泛用于农作物除草和草坪养护[2]。2,4-D的水溶性较高,挥发性较低,在自然界中难以生物 相似文献
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Manickam Matheswaran Il Shik Moon 《Journal of Industrial and Engineering Chemistry》2009,15(3):287-292
The ozonation of phenol wastewater treatment system has been investigated with effective mass transfer between gas and liquid phase in a bubble column reactor. The designed bubble column reactor was investigated for increasing the rate of mass transfer of ozone, the rate of oxidation of phenol in the solution, the solubility and decomposition rate of ozone in the distilled water were also studied at different flow rates. The decomposition rate constants were calculated based on pseudo first order kinetics. The oxidation of phenol was investigated in order to provide the overall reaction rate constant for the reaction between ozone and phenol at 25 °C. The influence of the operating parameters like initial phenol concentration, ozone flow rate and pH for the destruction of phenol by ozonation were studied. The pseudo first order rate constant was depending on the initial concentration of phenol solution. A comparison of TOC removal percentage between bubble column reactor and bubble diffuser using ozonation were reported. 相似文献
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