选择性催化还原(SCR)脱硝催化剂钛钨粉原始粉体的对比

采用XRF、XRD、低温N2吸附曲线、SEM和FT-IR考察了国产和进口钛钨(WO3/TiO2)粉的组成及其微观结构.结果表明,国产和进口钛钨粉中Ti和W的含量相差不大,但是国产钛钨粉都含有少量P,而国外钛钨粉O和S含量较大.国产和进口钛钨粉中TiO2都为锐钛矿型晶型;其表面官能团基本相同;钛钨粉颗粒形貌类似,都为多孔物质,其比表面积相差不大,但是进口样品的孔容高于国产样品.     

Tailoring the simultaneous abatement of methanol and NOx on Sb-Ce-Zr catalysts via copper modification

● Cu addition enhances CH₃OH oxidation and alleviates its inhibitory effect on SCR. ● Cu addition improves the activation of SCR reactants in the presence of methanol. ● Damaged structure by more Cu addition decreases specific surface area and acidity. ● Excessive Cu addition would lead to the narrowing of SCR temperature window. Simultaneously removal of NO_x and VOCs over NH₃-SCR catalysts have attracted lots of attention recently. However, the presence of VOCs would have negative effect on deNO_x efficiency especially at low temperature. In this study, copper modification onto Sb_0.5CeZr₂O_x (SCZ) catalyst were performed to enhance the catalytic performance for simultaneous control of NO_x and methanol. It was obtained that copper addition could improve the low-temperature activity of both NO_x conversion and methanol oxidation, where the optimal catalyst (Cu_0.05SCZ) exhibited a deNO_x activity of 96% and a mineralization rate of 97% at 250 °C, which are around 10% higher than that of Cu free sample. The characterization results showed that copper addition could obviously enhance the redox capacity of the catalysts. As such, the inhibition effect of methanol incomplete oxidation on NO adsorption and NH₃ activation were then lessened and the conversion of surface formamide species were also accelerated, resulting in the rising of NO_x conversion at low temperature. However, excessive copper addition would damage the Sb-Ce-Zr oxides solid solution structure owing to Cu-Ce strong interactions, decreasing the surface area and acidity. Meanwhile, due to easier over-oxidation of NH₃ with more Cu addition, the temperature window for NO_x conversion would become quite narrow. These findings could provide useful guidelines for the synergistic removal of VOCs over SCR catalyst in real application.     

汽油车冷起动排气后处理技术

为满足即将实施密耦催化剂的国家第3阶段排放标准,汽油车排气冷起动问题显得尤为重要。采用如低起燃温度催化剂、密耦催化剂、HC捕集器、二次空气注入和电加热催化剂等在内的排气后处理技术,可以有效地减少污染物尤其是HC的排放。多种处理技术的结合和系统优化能够满足更加严格的排放标准。     

糠醇生产中铜铬废触媒资源化研究

对已有的糠醇生产中产生的废渣回收工艺进行了改进。将糠醛液相加氢生产糠醇产生的废渣于 130℃真空蒸馏回收废渣中的有机混合物 ,经过精馏获得糠醇与糠醛 ;剩余的固体废触媒与纯碱混合 ,经反射炉焙烧、水浸取、掺加石灰除硅、过滤得到铬酸钠水溶液 ;剩下的粗氧化铜经碱溶除铬、溶于硝酸得到硝酸铜溶液 ;将铬酸钠溶液、硝酸铜溶液按一定比例混合 ,加氨水搅拌 ,分离出的沉淀经传统方法焙烧活化、造粒制得新催化剂 ,回用于糠醛液相加氢生产糠醇。有机物、铬组分和铜组分的回收率均在 90 %以上     

城市生活垃圾催化气化制取富氢气体的研究

采用下吸式固定床气化炉,以煅烧白云石为催化剂水蒸气气化城市生活垃圾(MSW)有机组分,在气化温度为750~950℃,S/M(水蒸气和垃圾物料进料质量比)为0.57~1.28时,探讨了催化剂种类、气化温度和S/M等因素对富氢气体成分、产氢率、潜在产氢率、低位热值和碳转化率等的影响。较高气化温度有利于富氢气体的生成,增加碳转化率和产气率,但会降低富氢气体的热值;在实验条件下,富氢气体中H2体积分数最高达53.29%,产氢率达到7.13~46.52mol/kg,潜在产氢率为55.48~90.11mol/kg;镍基催化剂催化效果优于煅烧白云石,能大幅增加H2含量,使焦油在850℃以上完全分解。     

碱性化学镀镍废液的净化处理

找到了一种处理碱性化学镀镍废液的新方法 ,研究了镀液组成、温度、时间、漂白粉浓度对化学镀镍废液处理结果的影响。结果表明 ,用漂白粉处理碱性化学镀镍废液是可行的。     

V2O5/ACF催化剂用于烟气低温脱硝的研究

采用等体积浸渍法制备V_2O_5/ACF,CuO/ACF和Fe_2O_3/ACF催化剂,在H_2O和SO_2存在下,三种催化剂选择性催化还原(SCR)NO_x的活性依次为V_2O_5/ACF>CuO/ACF>Fe_2O_3/ACF.对V_2O_5/ACF催化剂中V_2O_5担载量、反应温度和反应空速对脱硝活性的研究表明,当H_2O和SO_2存在时,V_2O_5的最佳负载量为0.5wt%,在反应温度为180℃,空速为2000 h~(-1)时,NO转化率可达84%,表明该催化剂具有良好的抗H_2O和SO_2毒化的能力.     

蜂窝状微量贵金属催化剂对几种典型VOCs的催化氧化性能

研制出了用于催化氧化废气中挥发性有机化合物(VOCs)的蜂窝状微量贵金属催化剂.用浸渍法制备催化剂Pt-Ce-La-Zr/Al2O3,并在自行设计的活性检测系统上,对用该催化剂净化含有苯、甲苯、乙醇、正己烷的模拟废气进行了研究,考察了空速、质量浓度等因素对催化剂活性的影响.实验结果表明,该催化剂对上述几种典型的VOCs气体都具有较低的起燃温度,其催化转化活性较好.     

蜂窝状SCR脱硝催化剂成型配方选择

通过对钒钛基蜂窝状SCR脱硝催化剂的制备工艺研究,探索了二氧化钛(TiO2)载体及成型剂配方对产品机械性能及脱硝活性的影响.分别选用工业级硫酸法锐钛型TiO2和进口商业纳米锐钛型TiO2为载体原料,所考察的主成型剂包括二氧化硅(SiO2),活性氧化铝(γ-Al2O3),以及SiO2和硼酸(H3BO3)的混合粉体.进一步对载体及所制备催化剂样品进行表征,机械强度及脱硝活性测试.结果表明,商业纳米级TiO2较工业级TiO2在杂质含量、粉体粒径、分散度等方面占有明显优势,但TiO2晶粒尺寸要高于后者,比表面积亦低于工业级样品.在SCR催化剂制备上,相对工业级TiO2而言商业纳米级TiO2制备样获得了较高的机械强度,但其在脱硝活性方面并不占有优势.而对主成型剂配方的探索显示,以SiO2与H3BO3按一定比例混合得到的成型剂配方不但能够显著提高蜂窝状催化剂的机械性能,另一方面也能够维持其较高的脱硝活性,因此该配方作为钒钛基SCR催化剂的成型剂是合理可行的.     

Characteristics and mechanisms of 4A zeolite supported nanoparticulate zero-valent iron as Fenton-like catalyst to degrade methylene blue

4A zeolite supported nanoparticulate zero-valent iron (nZVI/4A zeolite), synthesized through borohydride reduction method, was used as a catalyst with H₂O₂ to build Fenton-like reaction system to degrade methylene blue (MB) in model wastewater. The characteristics and primary mechanisms of the catalyst were investigated. The results show that nZVI/4A zeolite has the potential as a Fenton-like catalyst, and (about 30 mg/L) MB was degraded completely in 3 h with 10 mM H₂O₂, 0.2 g/L catalyst, and initial pH of 3.0. The MB degradation rates were obtained at least 70% in the tests with initial pH ranged from 2.0 to 9.0 and the catalyst dose rose from 0.2 to 5.0 g/L. Importantly, the catalyst also has a distinctive ability to increase the solution pH value from its initial acidic pH and then maintain the value at close to neutrality. This ability was controlled by both the initial pH and the catalyst dose. MB degradation clarified that hydroxyl radical was the dominated active oxidative specie in the tests with initial acidic pH and low catalyst dose (less 2.5 g/L); otherwise, Fe(VI) oxidation was the main mechanism for MB degradation; and the two processes shared synergistic effect in MB degradation in the present test. The catalyst has high operational stability in both of the composites with low iron leaching (less 2%) and catalyzing ability. Therefore, nZVI/4A zeolite has great potential as a Fenton-like catalyst and is used with H₂O₂ to build Fenton-like system which could be used to degrade MB efficiently.