废SCR脱硝催化剂中钨和钒的浸出实验研究

废SCR脱硝催化剂中钨和钒的浸出是实现其回收的关键.采用碳酸钠混合焙烧-稀硫酸浸出法,对废SCR脱硝催化剂中金属钨和钒的浸出实验进行了研究,考察了焙烧温度t_1(℃)、焙烧时间t_2(h)、硫酸浓度c(v/v)、液固比w、浸出温度t_3(℃)、浸出时间t_4(h)、Na_2CO_3与催化剂的质量比m(Na_2CO_3)/m(催化剂)等因素对钨和钒浸出率的影响.结果表明,在t_1为800℃、t_2为3 h、c为2%、w为8:1、t_3为80℃、t_4为4 h、m(Na2CO3)/m(催化剂)为1.2的反应条件下,废SCR脱硝催化剂中钨和钒的浸出率可分别高达99.08%、98.49%,为后续钨和钒的高效提取与回收提供了有利的条件.     

Combined steam-dry reforming of toluene in syngas over CaNiRu/Al2O3 catalysts

Cracking, steam reforming, dry reforming, and combined steam and dry reforming of toluene in model syngas were performed using catalysts to simulate tar removal produced during biomass gasification. The catalysts were prepared by adding Ru, Ca, and Mn to Ni-based catalysts, and their properties were measured using BET, pulse CO chemisorption, XRD and TG. In steam and dry reforming of toluene, a high toluene conversion was observed with increasing Ca content in the catalyst and catalysts containing Ca showed a higher activity than those containing Mn. In combined steam-dry reforming with syngas, 1%CaNiRu/Al₂O₃ indicated a conversion of 93.9% at 800°C.     

Application of TiO2 nanoparticles for eco-friendly biodiesel production from waste olive oil

An environmentally benign, simple, and efficient process has been developed for biodiesel production from waste olive oil in the presence of a catalytic amount of TiO₂ nanoparticles at 120°C with a conversion of 91.2% within 4 h. The present method affords nontoxic and noncorrosive medium, high yield of biodiesel, clean reaction, and simple experimental and isolation procedures. The catalyst can be recycled by simple filtration and reused without any significant reduction in its activity.     

钙钛矿型催化剂催化燃烧VOCs的抗水蒸气性能研究

用柠檬酸溶胶-凝胶法制备了La0.8M0.2CoO(3M=Sr,Ce,Ba,Ca)4种钙钛矿型复合氧化物催化剂。通入相对湿度为70%的甲苯测试表明,相比较于没有水蒸气存在的情况,4种催化剂的催化活性都有所下降。同时还可发现,A位部分取代的离子不同,催化剂的催化活性下降程度不同,即抗水蒸气性能也不同。所制备的四种催化剂的抗水蒸气性能依次为La0.8Sr0.2CoO3>La0.8Ce0.2CoO3≈La0.8Ca0.2CoO3>La0.8Ba0.2CoO3,其ΔT50%分别为12℃、20℃、20℃和50℃左右,说明除La0.8Ba0.2CoO3外,其它3种对水蒸气具有一定的抗中毒性能。XRD、BET和SEM表征结果证实,水蒸气分子与甲苯分子竞争吸附占据催化剂表面部分活性位,使用于催化氧化甲苯的有效活性位相对减少;同时其与活性组分在高温下发生反应生成新物质,在催化剂表面形成一层致密的涂层,堵塞了原来的孔道结构,从而使催化剂比表面积减少而活性下降。     

负载型TiO2在印染废水降解中的失活及原因分析

研究了负载型TiO2光催化剂在印染废水降解中的失活及其产生的原因。实验结果说明，催化剂活性下降的主要原因有：废水中不溶于水的染料等悬浮物和催化反应中产生的无定形碳在催化剂表面的吸附；高含量的无机离子对催化剂活性位的占据或在表面的沉积；长时间的使用和反复冲洗使TiO2负载量减少。通过同时采用灼烧和酸洗的方法可以使TiO2的活性恢复到新催化剂的69．5％。     

Preparation of MnO2 decorated Co3Fe1Ox powder/monolithic catalyst with improved catalytic activity for toluene oxidation

In this paper, KMnO₄ was used to pre-treat Co₃Fe-layered double hydroxides (LDH) precursor to prepare MnO₂ decorated Co₃Fe₁O_x catalyst. The toluene oxidation performance of the catalyst was investigated systematically. The optimized 0.1MnCF-LDO catalyst exhibited the best catalytic performance, and the temperatures of 50% and 90% toluene conversion (T₅₀ and T₉₀) were 218 and 243°C, respectively. The apparent activation energy (E_a) was 31.6 kJ/mol. The characterization results showed that the pre-redox reaction by KMnO₄ could increase the specific surface area, Co³⁺ species amount and oxygen defect concentration of the catalyst, which are the main reason of the improved toluene catalytic activity. Besides, this method was also applied to enhance toluene oxidation of iron mesh based monolithic catalyst. The 0.1MnCF-LDO/Iron mesh (IM) catalyst showed a 90% toluene conversion at around 316°C which was much lower than that of without MnO₂ addition (359°C). In addition, the water resistant of all the catalysts was studied as well, all the samples showed relatively good water resistance. The toluene conversion still remained to be over >80% even in the presence of 10 vol.% water vapor.     

Na2SO4中毒SCR催化剂对SO3生成特性的影响

为研究Na₂SO₄中毒SCR催化剂（V₂O₅-WO₃/TiO₂催化剂）对SO₃生成特性的影响,采用湿式浸渍法制备w（Na）为3%的Na₂SO₄中毒SCR催化剂,并通过N₂物理吸附/脱附、XRD（X射线衍射）技术、SEM（扫描电镜）、XPS（X射线光电子能谱）分析技术对催化剂的物理化学特性进行表征.结果表明:①随着反应温度的升高,所有催化剂上的SO₃生成率逐渐增加.当温度升至490℃时,SCR催化剂上的SO₃生成率为0.85%,而3% Na₂SO₄中毒SCR催化剂上的SO₃生成率高达1.36%.SO₄2-的存在导致V-O-S增多,从而促进SO₃的生成.②随入口ρ（SO₂）的增加,SO₃生成率呈下降的趋势.当入口ρ（SO₂）为1 000 mg/m3时,3% Na₂SO₄中毒SCR催化剂上的SO₃生成率为1.02%,而SCR催化剂上仅为0.60%.ρ（SO₂）对SO₃生成率的影响主要依赖于温度和催化剂活性位点数等.③N₂物理吸附/脱附、XRD和SEM表征结果表明,与SCR催化剂相比,Na₂SO₄中毒SCR催化剂表面有Na₂SO₄的积聚,出现了裂纹和大孔隙,催化剂的比表面积和孔容下降,这些变化均不利于催化剂的催化性能;XPS结果表明,Na₂SO₄的加入提高了表面化学吸附氧含量,降低了活性组分中w（V4+）/w（V5+）的值.研究显示,相比于SCR催化剂,Na₂SO₄中毒SCR催化剂上的SO₃生成率大幅增加.      

Mesoporous cobalt monoxide-supported platinum nanoparticles: Superior catalysts for the oxidative removal of benzene

Mesoporous Co_3 O_4(meso-Co_3 O_4)-supported Pt(0.53 wt.% Pt/meso-Co304) was synthesized via the KIT-6-templating and polyvinyl alcohol(PVA)-assisted reduction routes.Mesoporous CoO(meso-CoO) was fabricated through in situ reduction of meso-Co304 with glycerol,and the 0.18-0.69 wt.% Pt/meso-CoO samples were generated by the PVA-assisted reduction method.Meso-Co_3 O_4 and meso-CoO were of cubic crystal structure and the Pt nanoparticles(NPs) with a uniform size of ca.2 nm were well distributed on the mesoCo_3 O_4 or meso-CoO surface.The 0.56 wt% Pt/meso-CoO(0.56 Pt/meso-CoO) sample performed the best in benzene combustion(T_(50%)=156℃and T_(90%)=186℃at a space velocity of 80,000 mL/(g h)).Introducing water vapor or C02 with a certain concentration led to partial deactivation of 0.56 Pt/meso-CoO and such a deactivation was reversible.We think that the superior catalytic activity of 0.56 Pt/meso-CoO was intimately related to its good oxygen activation and benzene adsorption ability.     

介孔ZnO负载Fe-Cu-Zr复合催化剂用于催化燃烧降解乙酸丁酯

采用醇热法制备了有序球状介孔ZnO负载Fe-Cu-Zr复合催化剂,应用BET、SEM、XRD、XPS等对不同物质的量比催化剂进行了表征,研究了催化降解乙酸丁酯的活性及其影响因素,并推测了降解机理.结果表明,铁铜锆复合催化剂颗粒均匀,分散性较好,孔径大部分小于50 nm,比表面积为46~68 m²·g^-1.各活性成分能够共存和协同发挥作用,铁、铜、锆离子吸附在氧化锌晶胞内,粒子间量子作用力促使晶胞表面积略有变大.锆能够提高3种活性成分间的作用力,可以调节表面电子密度,促使结合能向低的方向偏移,增强催化剂的氧化还原能力.随着锆比例的增大,催化剂的活性也随之增强;随着初始浓度、空速、相对湿度的增加,乙酸丁酯降解效率均有所下降.在乙酸丁酯初始浓度为2590 mg·m^-3、空速为9000 h^-1的工况下,ZnO-3M催化剂降解乙酸丁酯的T₅₀为116 ℃,T₉₀为200 ℃,270 ℃时CO₂转化率达96%,具有良好的低温催化活性和稳定性.乙酸丁酯催化氧化主要中间产物为少量的低级酸和低碳醇,最后被彻底氧化成CO₂和H₂O.     

新型磁性Mn0.6Zn0.4Fe2O4@CdS纳米复合光催化剂的制备及其吸附和光催化特性

以两步水(溶剂)热法制备了一种新型磁性Mn_(0.6)Zn_(0.4)Fe_2O_4@CdS纳米复合光催化剂,并采用X-射线衍射(XRD)、比表面(S_(BET))、扫描电镜-能谱(SEM-EDX)、紫外漫反射(UV-vis)、透射电镜(TEM)、磁滞回线(VSM)和价带能谱(VB-XPS)等手段对制备的铁氧体、CdS和复合材料进行了表征分析.结果发现,得到的材料元素含量与设计预期值吻合,纯相晶格参数与理论值匹配较高,特征峰证实复合材料中存在尖晶石铁氧体和CdS晶格;高分辨透射电镜(HR-TEM)分析表明,CdS有效地附着在铁氧体上,且在可见光区发生了红移.利用该材料对亚甲基蓝(MB)进行了暗室吸附和光催化活性的系统研究,结果表明,复合物吸附速率较快,适宜用Langmuir模型描述吸附平衡,最大吸附容量q_(max)高达79.6 mg·g~(-1);在测试的3个样品中,复合物光催化活性最高,经5次重复光催化实验,MB的降解率仍可保留在50%以上,且易磁分离回收;此外,通过自由基和空穴捕获实验、光致发光(PL)和电子顺磁共振(ESR)测试分析提出了MB降解机理.