Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process

Characteristics of toluene decomposition and formation of nitrogen oxide (NO_x) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al₂O₃/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO₂ selectivity. In addition,NO_xwas suppressedwith the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NO_x suppression. The MnOx catalyst exhibited the lowest concentration of O₃ and highest CO₂ selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.     

Fabric-filter-supported catalyst for removal of harmful solid and gaseous compounds in municipal waste incinerator exhaust gas: characteristics of NO x reduction

We have investigated a fabric-filter-supported catalyst for removing harmful solid and gaseous compounds simultaneously from municipal incinerator exhaust gas. We studied the ways in which the efficiency of NO _x removal is influenced by filter temperature, gas flow rate, and catalyst content. The reduction of the catalyst content by mechanical reverse washing was investigated, and the state of the catalyst supported in the fabric filter was also observed using a scanning electron microscope. The catalyst supported by the fabric filter showed a removal efficiency above 75% when the filter temperature was 200°C, the gas flow rate was 1 m/min, and the catalyst content of the fabric filter was above 300 g/m². The catalyst was supported uniformly on the fibers of the fabric filter, and fine catalyst particles remained on the fibers after mechanical reverse washing. Received: October 15, 1997 / Accepted: March 19, 1999     

H₂-rich syngas production by fluidized bed gasification of biomass and plastic fuel

This paper reports the results of gasification tests using a catalytic fluidized bed gasifier to obtain a H₂-rich stream by feeding different pellets made of wood, biomass/plastic and olive husks to the gasifier. The effects of both the steam supply and an in-bed catalyst on gasifier performance have been investigated. In general, pelletization was an effective pre-treatment for improving the homogeneity of the fuel and the reliability of the feeding devices. The use of biomass/plastic pellets in a catalyst bed yielded good results in terms of the hydrogen concentration (up to 32% vol.), even if an increase in tar production and in the fine/carbon elutriation rate was observed in comparison with wood pellets.     

程序升温条件下铁及其氧化物在CO存在时对N2O的还原机理

应用热综合分析仪（TG－FTIR）研究了在还原性气氛下Fe及其氧化物对N2O的催化还原 作用。研究发现铁氧化物对氮氧化物的催化还原能力相当弱，而Fe可以高效地降低N2O分解的初始温度和提高N2O向N2的转化率。在Fe和CO的作用下，N2O的初始分解温度为920K和1000K。在1123K时，N2O的转化率达到95％和805。TG／DSC曲线表明了在Fe与N2O反应过程中CO的作用表现为通过与N2O在反应表面的竞争吸附使铁氧化物还原为金属铁，X射线衍射证明Fe与N2O反应后的氧化物为Fe2O3；扫描电镜对反应后Fe表面物理形态的研究发展，在CO作用下，Fe的表面呈松散结构，可以保证Fe对氮氧化物反应的连续进行。     

催化技术去除柴油机排放碳颗粒的研究进展

综述了柴油机排放碳颗粒催化燃烧中运用的贵金属催化剂、过渡金属催化剂、(类)钙钛矿催化剂以及催化技术与低温等离子体技术协同作用的最新研究进展,介绍了上述催化剂和催化技术的作用机理,并探讨了它们在实际应用中存在的问题和应用前景。     

催化铁内电解法处理难降解有机废水

催化铁内电解法是一种新型的有效处理废水的方法。在传统的铁碳内电解中加入无机催化剂铜，扩大原电池的两极电位差，使更多的有机物得到还原。结果表明，催化铁内电解法可改善难降解有机废水的可生化性，使活性艳红染料废水的B/C比从0升高到0.15。运行成本低廉、预处理能耗低，催化剂铜经连续运行数月后未发生纯化现象，只需一次性投资。     

LS—931Al2O3基硫磺回收催化剂的工业应用

LS－931催化剂是新开发的Al2O3基硫磺回收催化剂，经洛阳炼油厂5000t/a装置使用考察结果证实其具有高活性和稳定性运行的特点。在第一转化器使用LS－931Al2O3基催化剂及在第二转化器仍然使用旧的LS－811Al2O3催化剂的情况下，与原来单纯使用LS－811Al2O3催化剂相对比，装置总硫转化率可提高1％左右，有机硫水解率达到96.4%，尾气中的硫化物含量则稳定地降至1％（V）以下。     

Ni,Fe氧化物对吐氏酸废水催化臭氧化研究

用浸渍法和附着沉淀法制备了６种以Ｎｉ、Ｆｅ为活性组分，γＡｌ２Ｏ３载体的国型催化剂，催化臭经处理难生物降解的典型染料中间体废水－吐氏酸废水。初始ＣＯＤｃ浓度为１５００ｍｇ／Ｌ左右的废水，当臭氧投加量为０．８ｇ／Ｌ时，在活性最高的催化剂作用下，ＣＯＤＣｒ去除率大于５０％，而没有催化剂作用时小于３０％。     

湿式催化氧化法处理工业废水

介绍了有机废水催化氧化处理的进展情况及科研成果。     

Investigation on the urea deposit formation and thermal decomposition characteristics in the SCR aftertreatment system of a diesel engine

Selective catalytic reduction is the most efficient and reliable equipment for NOx control in current diesel engines. However, the issue of urea crystallization becomes increasingly serious with the implement of the new emissions standards. In this paper, urea deposit samples collected from engine test bed and tube furnace were characterized by thermogravimetric analysis and Fourier transform-infrared analysis to aid the comprehension of urea deposit formation. Moreover, thermogravimetric tests were conducted to disclose the effects of catalyst on the thermal decomposition processes of urea deposit. The results indicated that less temperature resistant species are formed in the engine test bed than in the tube furnace at conditions with the same temperatures. The main compositions in the World Harmonized Transient Cycle (WHTC) urea deposits are urea, cyanuric acid (CYA) and ammelide, implying that accelerating the decomposition of these species could prevent the accumulation of urea deposit. CuWTi, Cuβ and CuZSM catalysts could lead to increased yield of CYA during pure urea thermolysis. Cuβ, CuWTi and VWTi catalysts tend to promote the thermolysis of CYA while VWTi has the most significant catalytic effects on the thermal decomposition of ammelide and ammeline.