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1.
张志红  赵秀峰 《工业催化》2013,21(11):73-76
以钛酸丁酯和磷钨酸为主要原料,采用溶胶-凝胶法制备H3PW12O40/TiO2光催化剂,采用红外光谱、X射线衍射、热重分析和比表面分析对光催化剂进行表征。结果表明,H3PW12O40/TiO2光催化剂为无定形态,比表面积202 m2·g-1,杂多阴离子保持了Keggin骨架结构。在TiO2中掺杂H3PW12O40,使催化剂的光响应范围扩展到可见光区,从而提高光催化活性。光催化剂对甲基橙、酸性红、罗丹明B和亚甲基蓝均有较好的光催化降解活性,催化剂易于分离,重复使用稳定性较好。对甲基橙降解的适宜条件为:1.7×10-5 mol·L-1甲基橙溶液50 mL,H3PW12O40/TiO2光催化剂用量0.03 g,500 W碘钨灯照射60 min,此条件下,甲基橙脱色率可达到96%。  相似文献   

2.
采用溶胶-凝胶法制备TiO2-SiO2,用浸渍法将H2PW12O40负载在TiO2-SiO2上,制得H3PW12O40/TiO2-SiO2光催化剂。探究在模拟自然光条件下,光照时间、甲基红溶液初始浓度、催化剂用量和溶液pH对甲基红可见光催化降解的的影响。实验结果显示,在光照时间为15min.甲基红溶液初始浓度为15mg/L.催化剂用量为1.8g/L以及pH为2的优化条件下,甲基红的光降解率高达99.7%。光催化降解甲基红溶液为一级动力学反应。  相似文献   

3.
本文以二氧化硅负载磷钨酸(H3PW12O40/SiO2)为催化剂,丁醛和乙二醇为原料合成丁醛乙二醇缩醛,探讨了H3PW12O40/SiO2/SiO2对缩醛反应的催化活性,研究了醛醇物质的量比、催化剂用量、反应时间等因素对产物收率的影响。实验结果表明:H3PW12O40/SiO2/SiO2是合成丁醛乙二醇缩醛的良好催化剂。在固定丁醛用量为0.2mol的情况下,n(丁醛):n(乙二醇)=1:1.4,催化剂的用量占反应物料总质量的1%,环已烷用量为4mL,反应时间为45min的条件下,产品收率可达77.6%。  相似文献   

4.
以硫酸改性后的硅藻土为载体,Keggin结构磷钨酸为活性组分,通过浸渍法制备出负载型催化剂H3PW12O40/改性硅藻土,并对催化剂进行傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)和N2-程序升温脱附(N2-TPD)表征。结果表明:酸改性后硅藻土的微孔增大增多,比表面积增大。H3PW12O40均匀分布在改性硅藻土载体上,负载后磷钨酸仍保持Keggin结构。以H3PW12O40/改性硅藻土为催化剂催化乙酸和正丁醇液相合成乙酸正丁酯,通过正交试验探索优化工艺条件。在较优工艺条件下,即w(40%H3PW12O40/改性硅藻土)=1.1%(基于反应物质量),n(酸)∶n(醇)=1∶3,125℃反应2.0h,酯化率高达98.1%。催化剂重复催化使用5次,酯化率仍可达86.1%。H3PW12O40/改性硅藻土可作为催化合成乙酸正丁酯的高效催化剂,具有活性高、用量少、价格低廉、制备简单、后处理简便、无废液排放等优点。  相似文献   

5.
磷钨酸盐催化转化葡萄糖合成乙酰丙酸   总被引:5,自引:0,他引:5       下载免费PDF全文
曾珊珊  林鹿  刘娣  彭林才 《化工学报》2012,63(12):3875-3881
制备了一系列金属离子修饰的磷钨酸盐(MXH3-2XPW12O40,M=Zn,Cu,Cs,Ag)催化剂,并将磷钨酸银盐(Ag3PW12O40)用于水解葡萄糖制备乙酰丙酸的实验中。采用FTIR、XRD、SEM和EPMA等技术对磷钨酸盐性能进行了表征,并分析了磷钨酸银盐催化剂在反应前后结构和表面元素相对含量的变化。考察了反应温度、反应时间、催化剂用量和葡萄糖浓度等对乙酰丙酸得率的影响。结果表明:合成的磷钨酸盐具有磷钨酸的Keggin结构,并且Ag3PW12O40催化剂在多次使用后Keggin结构没有被破坏。在催化合成反应中,在反应温度200℃、反应时间2 h、Ag3PW12O40催化剂用量0.7 g和葡萄糖浓度40 g·L-1的条件下,乙酰丙酸的最大得率可达到81.61%,催化剂可重复利用。  相似文献   

6.
周勇 《山西化工》2023,(3):41-44
对石墨烯复合金属离子掺杂纳米二氧化钛光催化材料在污染物治理、CO2还原和资源化、H2生产等方面的研究进展进行了论述。石墨烯复合金属离子掺杂纳米二氧化钛光催化材料相较于纳米二氧化钛,其禁带宽度变窄,提高了在可见光区的吸收性能,提高了光催化活性,提高了污染物降解率、CO2还原和资源化的产率和H2生产效率。  相似文献   

7.
以H3PW12O40/ZrO2-WO3为催化剂,丙酸和正丁醇为原料合成丙酸正丁酯。探讨H3PW12O40/ZrO2-WO3对缩醛酯化反应的催化活性,较系统地研究了酸醇物质的量比、催化剂用量、反应时间等因素对产物收率的影响,实验表明:H3PW12O40/ZrO2-WO3是合成丙酸正丁酯的良好催化剂;在n(丙酸):n(正丁醇)=1:1.4,催化剂用量占反应物量总质量的1.5%,环己烷为带水剂6ml,反应时间45min的最佳条件下,丙酸正丁酯的收率可达85.9%。  相似文献   

8.
正丁醛自缩合合成辛烯醛是工业生产辛醇的重要步骤之一。首先考察了3种杂多酸H3PW12O40、H4SiW12O40和H3PMo12O40对正丁醛自缩合反应的催化性能,发现H4SiW12O40的催化性能最好。其次,利用浸渍法制备了负载型H4SiW12O40催化剂,考察了载体和制备条件对催化剂性能的影响,确定以SiO2为载体,H4SiW12O40负载量为50%(质量分数),在150℃焙烧2 h的制备条件。探讨了反应条件对催化剂性能的影响,确定了适宜反应条件:催化剂与正丁醛的质量比为0.15,反应温度120℃,反应时间6 h。在此条件下,正丁醛的转化率为90.4%,辛烯醛的选择性为89.2%。通过对催化剂进行ICP-AES分析和XRD表征,发现活性组分流失是造成催化剂稳定性差的主要原因。为减缓H4SiW12O40的流失,以[emim]BF4离子液体为模板剂,采用溶胶-凝胶法制备了H4SiW12O40/SiO2催化剂,实验结果表明,催化剂稳定性有一定程度的提高。  相似文献   

9.
采用水热法制备不同铁掺杂比例下的钨酸铋复合光催化剂,通过SEM、UV-Vis和PL表征手段对材料的结构及其光学性能等进行了表征。以罗丹明B作为目标污染物,考查了Fe/Bi2WO6复合材料的降解能力。结果表明,掺杂量为11%时,复合光催化剂在光催化-芬顿协同作用下的降解能力最好,此外,对催化剂投加量、H2O2投加量、p H等反应条件进行优化。最后提出了光芬顿降解机理。  相似文献   

10.
以二氧化钛负载磷钨钼酸H3PW6Mo6O40/TiO2-WO3为催化剂,环己酮和1,2-丙二醇为原料合成环己酮1,2-丙二醇缩酮。探讨H3PW6Mo6O40/TiO2-WO3为对缩酮反应的催化活性,较系统地研究了酮醇物质的量比、催化剂用量、带水剂用量、反应时间等因素对产物收率的影响。实验表明:H3PW6Mo6O40/TiO2-WO3为是合成环己酮1,2-丙二醇缩酮的良好催化剂,在固定环己酮的物质量为0.2mol,n(环己酮):n(1,2-丙二醇)=1:1.3,催化剂的用量占反应物料总质量的1.2%,带水剂环己烷的用量为6mL,反应时间45min的适宜条件下,环己酮1,2-丙二酵缩酮的收率可达88.5%。  相似文献   

11.
The selective oxidation of cyclopentene by aqueous H_2O_2 using H_3PW_(12)O_(40) and tetrabutyl ammonium bromide(TBAB) as a phase transfer catalyst has been investigated. The results show that the presence of TBAB significantly improved the oxidation selectivity of cyclopentene. The effects of the reaction conditions on the conversion of cyclopentene were investigated in detail. The optimal reaction conditions are as follows: the H_3PW_(12)O_(40) to TBAB molar ratio, 1:1–1:3; H_3PW_(12)O_(40) to cyclopentene molar ratio,0.54:100–0.64:100; and molar ratio of H_2O_2 to cyclopentene, 1.6:1. The conversion reached to 59.8% in 4h at 35.0 °C, while the selectivity of glutaraldehyde was 38.0% and the selectivity of 1,2-cyclopentanediol was 55.6%. In addition, a route for oxidation of cyclopentene by aqueous H_2O_2 using a heteropoly acid and quaternary ammonium salt as a phase transfer catalyst was proposed.  相似文献   

12.
The photocatalytic degradation of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, a non-biodegradable nitrogenous organic compound) in water was optimised under UV radiation using titanium dioxide photocatalyst. The reactor used was a pilot scale cocurrent downflow contactor photocatalytic reactor (CDCPR), a system offering very high mass transfer efficiency. The effect of photocatalyst loading, initial substrate concentration, temperature, pH, and different combinations of UV, O2, H2O2 and TiO2 on the photocatalytic oxidation of DBU was investigated. The TiO2 photocatalyst used was Degussa VP Aeroperl P25/20, a granulated form of Degussa P-25, recently developed to ameliorate downstream catalyst separation problems. The CDCPR was fitted with an internally and vertically mounted 1.0 kW UV lamp. The reactions were carried out at 40–60 °C and 1 barg, with the reactor being operated in closed loop recycle mode and suspended photocatalyst being re-circulated. Optimisation of reaction conditions using a combination of TiO2, UV radiation and O2 gave the most rapid degradation and mineralisation of the DBU in comparison with other processes. Under optimised conditions, 100% degradation of DBU was achieved in 45 min, with a quantum yield of 7.39, using a 1 kW lamp, 0.5 g/dm3 TiO2, 100 mg/dm3 DBU, 1 barg, 50 °C and pH of 3.17. Investigating the reaction pathway and its modelling showed a first order dependency, incorporating the effect of first intermediates of degradation. The activation energy was found to be 54.68 kJ mol−1 showing a significant influence of temperature on the photocatalytic degradation of DBU.  相似文献   

13.
A series of bifunctional Ni-H3PW12O40/SiO2 catalysts for the hydrocracking of n-decane were designed and prepared. The evaluation results of the catalysts show that Ni-H3PW12O40/SiO2 catalysts possess a high activity for hydrocracking of n-decane and an excellent tolerance to the sulfur and nitrogen compounds in the feedstock. Under the reaction conditions: reaction temperature 300 °C; H2/n-decane volume ratio of 1500; total pressure of 2 Mpa and the LHSV 2 h−1, the conversion of n-decane over reduced 5%Ni-50%H3PW12O40/SiO2 catalysts is as high as 90%, the C5+ selectivity equal to 70%. In order to reveal the structure and nature of the catalysts, a number of characterizations including XRD, Raman, H2-TPD, NH3-TPD, XPS and FT-IR of pyridine adsorption were carried out. The characteristic results show that the high activity of the catalysts and high C5+ selectivity can be related to the unique structure of the H3PW12O40 and its suitable acidity.  相似文献   

14.
Esterification of acrylic acid with 1-butanol has been studied in a heterogeneous solid–liquid reaction system using a variety of solid acids including an acidic salt of H3PW12O40, Cs2.5H0.5PW12O40. The catalytic activity (per proton) of liquid acids such as heteropolyacids, H2SO4, and para-toluenesulfonic acid increased as the acid strength of the solution increased, but the difference in the activity among them was not significant. In the solid–liquid reaction system, Cs2.5H0.5PW12O40 exhibited the highest catalytic activity in the unit of catalyst weight among the solid oxide catalysts, while the activity of Cs2.5H0.5PW12O40 was less than those of organic resins such as Nafion and Amberlyst 15. Contrary to the liquid acids, the specific activity values (per proton) of solid acids were significantly different. It was demonstrated that the activity of Cs2.5H0.5PW12O40 was almost retained after the addition of water, while the activities of the organic resins greatly decreased. The water-tolerant property of Cs2.5H0.5PW12O40 is presumed to be due to the hydrophobic nature of the surface.  相似文献   

15.
W. Bahnemann  M. Muneer  M.M. Haque   《Catalysis Today》2007,124(3-4):133-148
The photocatalytic degradation of maleic hydrazide (1), propham (2), tebuthiuron (3), propachlor (4), chlortoluron (5), thiram (6), phenoxyacetic acid (7), 2,4,5-trichlorophenoxy acetic acid (8), 4-chlorophenoxy acetic acid (9), uracil (10), 5-bromouracil (11) and bromothymol blue (12) have been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics of the compounds were investigated under different conditions, such as types of TiO2, pH, catalyst concentration, substrate concentration, temperature and in the presence of different electron acceptors, such as hydrogen peroxide (H2O2), potassium persulphate (K2S2O8), ammonium persulphate (NH4)2S2O8 and potassium bromate (KBrO3) besides molecular oxygen. TiO2 Degussa P25 was found to be more efficient photocatalyst for the degradation of the model compounds as compared with other photocatalysts. The degradation products were analysed using GC/MS analysis technique and probable pathways for the formation of different products have been proposed.  相似文献   

16.
采用溶胶-凝胶法制备系列BixTi1-xO_2光催化剂以及N和Bi共掺杂Ti O_2光催化剂,采用XRD、UV-Vis、N2-物理吸附和TEM等对催化剂进行微观结构表征,以普通节能灯为光源,考察催化剂光催化氧化室内甲醛的性能。结果表明,在Bi掺杂的Ti O_2光催化剂体系中,Bi0.15Ti0.85O_2光催化剂催化降解甲醛效果最佳,400℃焙烧2.5 h,节能灯光照48 h,可将(1.05±0.05)mg·m-3甲醛降解至0.08 mg·m-3,甲醛转化率92.8%,达到室内空气质量标准。当N与Bi共掺杂时,节能灯光照24 h,Bi0.15Ti0.85O_2-N(0.2)光催化剂表现出最佳的光催化氧化降解甲醛性能,即可将甲醛由(1.05±0.05)mg·m-3降解至0.082 mg·m-3,甲醛转化率达92.0%,较Bi0.15Ti0.85O_2催化剂光催化效率提高50%。  相似文献   

17.
The degradation of omethoate was conducted using H2O2 as oxidant, TiO2 supported on NaY zeolite as photocatalyst and a 300 W lamp as light source. The effect of the calcination temperature of the photocatalyst, the amount of TiO2 loaded on NaY zeolite, the photocatalyst amount, the pH value and the radiation time on the degradation ratio of omethoate were investigated. The results show that TiO2/NaY zeolite photocatalyst prepared by sol-gel method had good photocatalysis. The photocatalytic optimum oxidation conditions of omethoate are as follows: the calcination temperature of the photocatalyst is 550°C,the amount of TiO2 loaded on NaY zeolite is 35.2 wt-%, the amount of photocatalyst is 5 g/L, pH=8 and the radiation time is 180 min. Under these conditions, the removal ratio of omethoate is up to 93%.  相似文献   

18.
The catalytic activity of tungstophosphoric acid and Pt loaded MCM-41 for the catalytic reduction of NOx with propene in the presence of water vapor was studied. Pt/MCM-41 was found to be most active, the loading with H3PW12O40 led to an improved selectivity to N2 formation and to an enhanced activity in the presence of water vapor. Hydrated tungstophosphoric acid generated additional sorption sites for C3H6 and led to a higher local concentration of the reducing agent on the catalyst surface, which was found to increase the activity of the Pt and H3PW12O40 loaded catalysts in the presence of water vapor.  相似文献   

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