Catalytic degradation of toxic organic dye using an aluminum-doped Cu0.4Zn0.6-xAlxFe2O4 (x = 0.0, 0.2, 0.4, 0.6) spinel ferrite in a photo-Fenton system

Catalytic activity of spinel ferrite in breaking down toxic dye materials are promising due to their uniqueness. In this study, aluminum-doped copper zinc ferrite, Cu_0.4Zn_0.6-xAl_xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6), a catalyst for toxic dye degradation is synthesized through chemical co-precipitation route. The formation of the spinel ferrite catalyst is initially confirmed by Fourier transform infrared spectra, which shows the frequency of metal-oxygen bond vibration at 539 and 427 cm⁻¹ attributed to the tetrahedral and octahedral sites respectively. Higher intensity sharp peak of X-ray diffraction for (311) plane is the evidence for the phase purity and the formation of spinel ferrite. The crystallite size is found to decrease with the increase of Al³⁺ ion. The surface structure of the obtained particles is investigated using a scanning electron microscope. Analyses of the material's magnetic characteristics using a vibrating sample magnetometer (VSM) revealed that it is, in fact, a soft magnet, as evidenced by the loop of its hysteresis, which is narrow. The catalytic degradation of methylene blue dye under the mechanism of the photo-Fenton process is studied with the obtained spinel ferrites and the result is found to be as high as 96.5%. The process follows pseudo-second order kinetics and the Langmuir isotherm.     

CePO4-TiO2固溶体的NH3-SCR活性

采用共沉淀法合成了不同Ce与Ti摩尔比的CePO₄-TiO₂复合材料,利用XRD、TEM、NH₃-TPD和H₂-TPR技术对其物理化学性质进行了表征,并对其NH₃-SCR活性进行了评价。实验结果表明：随着CePO₄含量的增加,催化剂的活性提高;当Ce与Ti的摩尔比为8:2时催化剂的活性最高,230 ℃的NO转化率达到100%,且具有更广的温度窗口,优于纯CePO₄。表征结果显示,CePO₄与TiO₂形成固溶体后,颗粒尺寸较为均匀,强酸位的数量增多,氧化还原性能提升,从而提高了催化剂的SCR反应活性,同时改善了其抗水抗硫性能。     

好氧触媒在造纸法再造烟叶污水处理中的应用分析

本文围绕好氧触媒在造纸法再造烟叶污水处理中的应用展开分析。如对好氧触媒在再造烟叶污水处理中的应用必要性及好氧触媒作用原理予以介绍,并对好氧触媒在造纸法再造烟叶污水处理中应用展开试验。     

Feasibility of honeycomb monolith supported sugar catalyst to produce biodiesel from palm fatty acid distillate (PFAD)

Carbon coated monolith was prepared by sucrose solution 65 wt.% via dip-coating method. Sulfonation of incomplete carbonized carbon coated monolith was carried out in order to synthesize solid acid catalyst. The textural structure characteristics of the solid acid catalyst demonstrated a low surface area and pore volume. Palm fatty acid distillate (PFAD), a by-product of palm oil refineries, was utilized as oil source in biodiesel production. The esterification reaction subjected to different reaction conditions was performed by using the sulfonated carbon coated monolith as heterogeneous catalyst. The sulfonation process had been performed by using vapour of concentrated H₂SO₄ that was much easier and efficient than liquid phase sulfonation. Total acidity value of carbon coated monolith was measured for unsulfonated sample (0.5 mmol/g) and sulfonated sample (4.2 mmol/g). The effect of methanol/oil ratio, catalyst amount and reaction time were examined. The maximum methyl ester content was 89% at the optimum condition, i.e. methanol/oil molar ratio (15:1), catalyst amount (2.5 wt.% with respect to PFAD), reaction time (240 min) and temperature 80 °C. The sugar catalyst supported on the honeycomb monolith showed comparable reactivity compared with the sugar catalyst powder. However, the catalyst reusability studies showed decrease in FFA% conversion from 95.3% to 68.8% after four cycles as well as the total acidity of catalyst dropped from the value 4.2 to 3.1 mmol/g during these cycles. This might be likely due to the leaching out of SO₃H group from the sulfonated carbon coated monolith surface. The leaching of active species reached a plateau state after fourth cycle.     

大肠杆菌吸附-化学还原法用废含金催化剂制备金纳米线

采用大肠杆菌吸附-化学还原法,以大肠杆菌(ECCs)为模板、十六烷基三甲基溴化铵为保护剂、抗坏血酸为还原剂,由废含金催化剂制备金纳米线(AuNWs)。采用XRD,SEM,TEM等技术对AuNWs进行表征。研究了AuNWs对罗丹明6G(R6G)和4-巯基苯甲酸(4-MBA)的拉曼散射信号的增强效果。实验结果表明:在制备过程中加入微生物ECCs,可使金回收率提高约20百分点;当溶液pH小于4时,反应2 h后,有大量呈线状的AuNWs聚集沉降,金回收率可达99%1以上。表征结果显示,AuNWs呈多晶结构,晶格间距为0.23 nm。表面增强拉曼散射分析表明,AuNWs对R6G和4-MBA具有良好的拉曼光谱增强性能。     

MCM-41分子筛负载铁铈催化降解甲基橙

采用等体积浸渍法制备了负载型有序介孔Fe-Ce/MCM-41催化剂。研究了该催化剂降解甲基橙的适宜工艺条件,并采用XPS,XRD,TEM技术对该催化剂进行了表征。实验结果表明,该催化剂Fenton氧化降解甲基橙的较适宜工艺条件为:溶液pH 5.0、甲基橙溶液初始质量浓度100 mg/L、催化剂加入量2.0 g/L、H_2O_2浓度20 mmol/L,在此适宜条件下反应120 min时,甲基橙去除率接近100%。表征结果显示:Fe-Ce/MCM-41催化剂主要由铁、铈、氧、碳4种元素组成;铁与铈的摩尔比接近3∶1;铁和铈主要以Fe_3O_4和CeO_2的形态存在于催化剂表面。     

γ-Al2O3负载多金属复合催化剂选择性催化还原烟气脱硝

以γ-Al₂O₃作为载体，先后负载CeO₂，MnC₂O₄，Fe（NO₃）₃，CrO₃，Ni（NO₃）₂，NH₄VO₃等多种金属组分制备γ-Al₂O₃负载多金属复合催化剂，并用于模拟烟气的选择性催化还原脱硝。通过SEM和XRD技术对催化剂进行了表征。表征结果显示：Fe，Mn，Cr的添加能增加催化剂的低温催化活性、提高催化剂的N₂选择性;γ-Al₂O₃对活性金属氧化物的负载效果良好。实验结果表明：各金属化合物的最佳加入量为 w（MnC₂O₄·2H₂O）=20%，w（Fe（NO₃）₃·9H₂O）=15%，w（CrO₃）=10%，w（Ni（NO₃）₂·6H₂O）=5%，w（NH₄VO₃）=10%，w（CeO₂）=5%，w（γ-Al₂O₃）=35%;以在最佳正交实验条件下制得的γ-Al₂O₃负载多金属复合物为催化剂，在脱硝反应温度为205 ℃的条件下，NO转化率为96.7%;γ-Al₂O₃负载多金属复合催化剂经5次重复使用，NO转化率仍可稳定在94%左右。     

钙钛矿型La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3催化剂的制备及其三效催化活性

采用自燃烧法制备了一组钙钛矿型复合氧化物La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3(x=0.9,0.7,0.5,0.3,0.1),并考察了其对CO、C_3H_6和NO的三效催化活性。XRD和SEM表征结果显示,La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3具有良好的钙钛矿型晶体结构,晶粒大小为纳米级并自组装成片状结构。催化剂的比表面积为14.73~22.43 m~2/g,含有微孔和介孔结构。催化活性评价结果表明:La_(0.8)Ce_(0.2)Fe_(0.1)Co_(0.9)O_3具有很好的三效催化活性,在理论空燃比的条件下,CO、C_3H_6和NO的起燃温度分别为195℃、264℃和290℃,完全转化温度分别为239℃、418℃和415℃,低温三效催化活性良好;Fe和Co的掺杂量同时影响着La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3的催化效果。     

石油化工催化剂生产过程中的职业病防治及应急处理

石化企业使用了大量的催化剂,催化剂开发、生产过程复杂,有许多原料和生产工艺,存在许多潜在的安全隐患和职业病危害因素。为预防催化剂生产过程中的事故,通过分析催化剂生产过程中的职业病危害分析,提出了相应的职业病防范及应急处置措施,加强催化剂生产过程中的职业病防治和应急处置能力,创造良好的经济、生态和社会效益,有效防止催化剂生产过程中发生安全事故和职业病。     

锰铈脱硝催化剂的制备及其再生性能研究

采用等体积浸渍法制备了一系列Mn-Ce-Ox复合氧化物脱硝催化剂用于NH3选择性催化还原(NH3-SCR)NO。考察了Mn/Ce摩尔比、焙烧温度、H2O和SO2对Mn-Ce-Ox复合氧化物脱硝催化剂活性的影响及催化剂中毒再生性能。结果表明:当NH3:NO=1:1,空速为5 000 h-1,550℃焙烧制得的Mn/Ce摩尔比为5∶1的Mn-Ce-Ox复合脱硝催化剂活性最佳,活性温度窗口为100~260℃,在此温度区间内催化剂活性大于90%。200℃时,Mn-Ce-Ox复合催化剂活性最高为97.84%;在10%(V/V)H2O蒸汽和300×10-6SO2共存条件下,200℃时,催化剂活性在开始反应2.5 h内迅速下降至53%左右,并在之后的6 h内没有明显变化;中毒催化剂经常温水洗再生处理、质量分数为3%的硝酸溶液再生处理和550℃焙烧2 h再生处理后200℃活性均能恢复到90%以上,其中中毒催化剂经质量分数为3%硝酸处理后活性恢复率最高。