Methane combustion on Mg-doped LaMnO3 perovskite catalysts

LaMn_1−xMg_xO₃ perovskite catalysts (x=0–0.5) were synthesised by the so-called “citrates method”, characterised (chemical analysis, TEM, BET, XRD, temperature-programmed desorption of oxygen) and tested for their activity towards the catalytic combustion of methane. The role of MgO as a textural promoter, which hinders the sintering of the catalyst crystals by geometrical interposition, has also been assessed. Finally, a kinetics study was performed on the most promising catalysts prepared (LaMnO₃ and LaMn_0.8Mg_0.2O₃). The major results obtained are: (i) Mg substitution in the basic LaMnO₃ perovskite has a positive effect on the catalytic activity only at low x values (x≤0.2); (ii) as opposed to the results of previous studies on the LaCr_1−xMg_xO₃ system, the role of MgO as a textural promoter is not always significant and depends strongly on the calcination temperature of the samples (800–1200°C) and on the value of x; (iii) an Eley–Rideal mechanism could satisfactorily fit the experimental kinetics results for both catalysts, even though, as opposed to LaMnO₃, the catalytic combustion over LaMn_0.8Mg_0.2O₃ seems to involve two different types of adsorbed oxygen species, depending on the operating temperature.     

基质组成对MgO-尖晶石浇注料抗渣性能的影响

采用静态坩埚法研究了添加不同组成尖晶石的ＭｇＯ－ 尖晶石浇注料基质组成与抗渣性能的关系。实验结果表明：随着基质中Ａｌ２Ｏ３ 含量增加,浇注料抗渣侵蚀能力减弱,而抗渣渗透能力增强。在基质中ＳｉＯ２ 含量固定在１０ ％ 的情况下,基质中Ａｌ２Ｏ３ 含量在３０ ％ ～５０ ％ 时浇注料抗渣侵蚀性能较好;Ａｌ２Ｏ３ 含量超过５０ ％ 时,侵蚀速率急剧增加两倍以上。不同组成尖晶石对浇注料抗渣侵蚀性能没有明显影响,但含富铝尖晶石的浇注料具有较好的抗渣渗透性能。     

薄板坯中间包镁质喷涂料的侵蚀机理

借助SEM、EDS、XRD等分析手段,观察和分析了用后中间包镁质喷涂料的显微结构,研究了镁质喷涂料的侵蚀机理。结果表明:在研究条件下,以烧结镁砂为主要原料的镁质喷涂料基质中低熔物与渗入的熔渣中的Al、Si、Ca、Fe反应生成复杂的钙铝铁硅酸盐,形成粘度适中的液相向原质层渗透,在使用温度梯度下形成一层致密层,阻止渣往涂料深处进一步渗透,提高了材料的抗侵蚀性能,实现涂料的长寿命;钢渣中的Fe、Mn、Si与MgO形成橄榄石固溶体,对涂料的抗侵蚀性能有一定贡献。     

The deactivation study of Co–Ru–Zr catalyst depending on supports in the dry reforming of carbon dioxide

Carbon dioxide reforming of methane was performed over Co–Ru–Zr catalyst (0.4 wt% Ru added, calcined at 400 °C) with different supports (SiO₂, γ-Al₂O₃ and MgO) in order to study their deactivation. The Co–Ru–Zr/γ-Al₂O₃ showed the highest activity at first, but severe deactivation was observed due to carbon deposition. Co–Ru–Zr/MgO exhibited low activity because of its low specific surface area. However, the high conversions could be obtained in Co–Ru–Zr/SiO₂, and activity was kept almost constantly for 500 h reaction. The characteristics of the catalysts, before and after the reaction, were investigated employing BET, XRD, TPR, TGA-DTA and TEM.     

Clean fuel-magnesia bonded coal briquetting

Benefaction from coal fines as solid fuel in Turkey is very much important for economical development. Beneficiation from washed coal fines in the industry using solid fuel at lump size and in the municipal areas as an household solid fuel may be only provided by hot briquetting of the coal fines. The most practical common way of that benefication from coal fines in our country have been hot binding by sulfite liquor–sulfite liquor-melas and lime mixtures. Harmful the flue content of sulfite liquor-melas may only be eliminated by lime, a type of solid additive. However, cold bonded briquettes produced from coal fines are environmentally free. Just ash contents of these briquettes increase at a certain degree and heat content of them decrease at a certain extent. By using magnesia binder showed in this study, Tunçbilek lignite fines have been briquetted by cold and hot briquetting techniques. The qualities of briquettes produced by cold binders were compared with to those produced by other hot binding methods As a result, magnesia binder showed the similar characteristics with those of the briquettes produced by only cold bonded gypsum. Use of magnesite mixture and gypsum just as only cold binder was not suitable for the requirements from the coal briquettes to be used as solid fuels, particularly from household fuels, but just only as cold additive should be used.     

氧化镁部分稳定氧化结超细粉末及其烧结特性

本文对氧化镁部分稳定氧化锆超细粉末的制备工艺和性能进行了实验研究。利用颗粒度分析仪、ＴＧ和ＤＴＡ热分析仪等测定了氧化镁部分稳定氧化锆粉末的性能。研究了粉末的烧结特性，测定了烧结密度随烧结温度及烧结时间的变化。利用热膨胀法对烧结过程中试样的长度变化作了模拟试验，以考察试样的收缩特征。     

转炉炉衬用镁质大砖的生产与应用

采用优质电熔高钙低硅镁砂 ,添加复合外加剂 ,用复合有机结合剂结合 ,制成了镁质大砖。介绍了该大砖的整体吊装法和炉帽外装法两种砌筑工艺。与普通镁碳砖相比 ,使用镁质大砖可以极大地减轻工人的劳动强度 ,缩短筑炉时间 ,保证炉役后期炉膛的规则性 ,有利于提高转炉炉龄 ,提高炉子作业率 ,降低生产成本     

中间包工作层用镁质浇注板的研制与应用

在分析原用硅质板存在问题的基础上 ,通过提高产品的抗侵蚀性和优化中间包结构 ,研制了中间包工作层用镁质浇注板。该镁质浇注板应用于小方坯连铸 ,寿命可达 34h ,取得了理想的效果     

碳化法处理巴盟菱镁矿

采用碳化法处理巴盟菱镁矿,以煅烧制得的轻烧镁为原料,经消化、碳化、浸出和煅烧后,可获得MgO品位大于99.41％的高纯活性产品,MgO回收率达61.34％。其最佳工艺条件：煅烧温度800 ℃,轻烧时间2.5 h,振动磨磨矿时间2.5 min,消化时间30 min,重镁水加温温度150 ℃,CO₂通气量8 L/min,通气时间3 min,固液比60∶1,二次碳化的pH值7.0。