共查询到20条相似文献,搜索用时 625 毫秒
1.
微孔玻璃是基于分相原理得到的。人们发现,由于Na_2O-B_2O_3-SiO_2系统中同时存在两种形成玻璃网络的氧化物B_2O_3及SiO_2,电价不平衡的[BO_4]四面体趋于获得Na_2O中的游离氧而形成含富Na_2O-Ba_2O_3的相,从而与含富XiO_2相分开,当这种分相玻璃浸于稀盐 相似文献
2.
As an industrial solid waste, pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion. Prior to the experiment, oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties, which presented significant influence on the redox performance of oxygen carriers. However, the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail. In this work, the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidized-bed reactor using CH4 as fuel. A series of pyrite cinder samples were prepared by controlling the calcination temperature. The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply. The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder. Considering CH4 conversion (80%–85%) and attrition resistance, the pyrite cinder calcined at 1050?℃ presented excellent redox properties. In the whole experiment process, the CO2 selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%. The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process. 相似文献
3.
以焦炉煤气(COG,coke oven gas)为燃料,研究了CaSO4载氧体在燃料反应器(FR,fuel reactor)内的还原性,从原子层面对反应路径进行了探讨分析。当反应温度较低时(100~300℃),主要发生CO-H2甲烷化反应和CH4-CaSO4热化学硫酸盐还原反应,CaCO3与H2S是该温度范围内的主要产物。当反应温度较高时(400~1000℃),CaSO4与CO、H2和CH4之间的还原反应占据了主导地位,CaS、H2O和CO2是该温度范围内的主要产物。当反应温度进一步升高时(1000~1400℃),CaSO4与CaS发生固固反应生成大量的副产物SO2和CaO。温度和压力对产物中硫化物的分布有很大影响,在反应温度为1000℃,压力为0.1 MPa时,焦炉煤气的燃烧反应进行的很充分,但是反应在加压条件下进行时,CaSO4、CaS和H2S含量会有明显的下降,而SO2含量有一定程度的增加。 相似文献
4.
利用溶胶凝胶法制成了Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米湿敏陶瓷薄膜。用扫描电镜和原子力显微镜对膜的表面形貌和显微结构进行表征,分析了处理方式对膜的表面形貌和微观结构的影响。制成的Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米湿敏陶瓷薄膜具有广谱抗菌、高效、无毒、持久和耐热等特点。湿敏特性测试结果表明:Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米陶瓷薄膜制品的感湿灵敏度高,具有较好的响应特性和稳定性。 相似文献
5.
6.
基于化学链燃烧新流程,采用固定床反应器研究了Cu基载氧体粒度、作为活性组分的Cu粉粒度及作为惰性载体的g-Al2O3粒度对载氧体反应性能的影响. 结果表明,载氧体的还原率及氧化率随Cu粉粒度减小而增大,Cu粉平均粒度小于63 mm时,载氧体还原率和氧化率达95%和93%以上. 载氧体还原过程中有少量CH4生成,生成量随Cu粉粒度减小而减少,Cu粉平均粒度小于32 mm时低于1%;当载氧体粒度接近g-Al2O3粒度时,载氧体的性能明显降低,只有g-Al2O3粒度明显小于载氧体粒度时,g-Al2O3才能起到分散活性组分、抑制活性组分烧结的作用. 相似文献
7.
制备了0.05wt%PdO/0.15wt%ZrO2/γ—Al2O3/Al2O3-SiO2纤维催化剂,考察了ZrO2对催化剂甲烷催化燃烧性能的影响。结果表明,当ZrO2的掺杂量为0.15wt%时催化剂活性最好,其甲烷完全转化温度为401℃。比表面积测定(BET)结果显示,加入γ-Al2O3极大地提高了催佬剂的比表面积;氧气程序升温脱附(O2-TPD)实验结果表明,加入适量ZrO2,提高了活性相PdO的分解温度,从而提高了催化剂热稳定性。对所制备的催化剂进行了实用性能考察表明:0.05wt%PdO/γ-Al2O3/Al2O3-SiO2纤维催化剂使用50次(100h)后烟气中的CO浓度提升为首次使用时的2倍、燃烧温度也提高了44℃;而添加了0.15wt%ZrO2的催化剂的使用性能非常稳定、预测其具有长的使用寿命。 相似文献
8.
Martin Keller Mehdi Arjmand Henrik Leion Tobias Mattisson 《Chemical Engineering Research and Design》2014
The chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) processes are novel solutions for efficient combustion with direct separation of carbon dioxide. These processes use a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor, where the fuel reacts with the solid oxygen carrier. When utilizing coal in CLC, the oxygen carrier particles could be affected through interaction with the ash-forming mineral matter found in coal, causing deactivation and/or agglomeration. In this work, possible interactions between minerals commonly encountered in coal and several promising oxygen carriers that are currently under investigation for their use in CLC are studied by both experiment and thermodynamic equilibrium calculations. Possible interaction was studied for both highly reducing and oxidizing conditions at 900 °C. Under highly reducing conditions pyrite was found to have by far the most deteriorating effect on the oxygen carrier particles, as the sulfur in the pyrite reacted with the oxygen carrier to form sulfides. Quartz and clay minerals were found to have a rather low influence on the oxygen carriers. Out of the oxygen carriers investigated, CuO/MgAl2O4 and the Mn3O4/ZrO2 oxygen carriers tended to be quite reactive towards mineral matter whereas ilmenite has been shown to be the most robust oxygen carrier. Although sulfur can clearly deactivate Ni, Cu and Mn based oxygen carriers under sub-stoichiometric conditions, when the fuel is converted fully to CO2 and H2O, sulfides are only expected for Ni-based oxygen carriers. 相似文献
9.
10.
11.
12.
组成与温度对R2O-CaO-ZnO-Al2O3-SiO2系统析晶的影响 总被引:1,自引:1,他引:0
通过大量的配方实验和OM、XRD分析,系统研究了R2O-Ca-ZnO-Al2O3-SiO2系统析晶和组成与热处理温度间的相互关系。研究结果表明,白榴石相仅在0.2K2O-CaO-ZnO-Al2O3-SiO2系统的低硅区析出,且高Al2O3含量有利于其析晶;锌黄长石相主要在ZnO含量较高的系统中析出。在ZnO含量为0.55mole的系统中,用Na2O等摩尔取代K2O,有减小锌黄长石相析晶区的趋势,但是在ZnO含量为0.35mole的系统中则相反,硅锌矿相主要在ZnO含量为0.55mole系统中的低SiO2区析出,在高CaO低ZnO含量的系统中析出的主晶相是β-硅灰石,尤其是用Na2O等摩尔取代K2O时,系统的组成一定时,析出晶相的种类和数量还受到热处理温度的显著影响。 相似文献
13.
化学链燃烧作为一种新颖的燃烧技术,在化石燃料燃烧释放能量的同时能够有效分离CO2。今以CO2为气化剂气化煤炭,基于Aspen Plus流程模拟软件,研究了煤/钙基载氧体化学链燃烧过程。结果表明,以CO2为煤气化剂,各反应器含水分少,可减少热损失。CaSO4载氧体具有载氧能力大以及反应活性良好等优点。气化炉中CO+H2含量随二氧化碳煤比增大逐渐增加后下降;随温度升高其含量先增加,后趋于平稳。燃料反应器中CO2+H2O含量随载氧体煤比增大,呈现先增大后减小的趋势;随温度升高其含量逐渐下降。空气反应器中CaSO4含量随空载比增大先增加后趋于平稳,随温度升高其含量趋于平稳后下降。气化炉中硫化物和氮化物含量随温度升高而下降,而燃料反应器和空气反应器中硫化物含量随温度升高增加趋势明显,氮化物含量变化不明显。最后确定了关键反应器操作参数:气化炉的二氧化碳煤比为1.8;燃料反应器的载氧体煤比为4.5;空气反应器的空载比为10.5和三反应器的操作温度分别为950、1000和1100℃。 相似文献
14.
对MgO-Al2O3-SiO2系统的分相与析晶进行了探讨,通过对不同组成点在热处理各阶段的试样进行XRD、TEM及DTA分析,研究了玻璃组成对玻璃的分相和析晶的影响.结果表明:当组成中MgO/Al2O3越大且同时SiO2含量越高,越利于该系统产生分相.当MgO/Al2O3大于3且SiO2含量大于68mol%时,水淬试样产生分相.SiO2含量较高时,分相液滴很容易聚集在一起,形成连通的蠕虫状分相粒子.随着SiO2含量的降低,玻璃的析晶放热峰温度逐渐降低,而且析晶放热峰变得尖锐,玻璃析晶趋势增强.当SiO2含量越低且MgO/Al2O3越大时,越利于该系统析晶. 相似文献
15.
16.
为了研究高温条件下Al2O3-C体系中氮化硅铁的状态,以闪速燃烧合成氮化硅铁、炭黑、刚玉粉为原料,将试样在高温炉中分别加热至1 450、1 500、1 600℃保温5 h,急速水冷后,对其进行XRD和显微结构分析。结果表明:1 450℃烧后试样的物相包含β-Si3N4、α-Si3N4、α-Al2O3和Fe3Si;1 500℃烧后试样的物相为β-Si3N4、SiC、α-Al2O3和Fe3Si;1 600℃烧后试样中Si3N4大部分转变为SiC,其他物相未发生变化。在升温过程中,氮化硅逐渐转化为碳化硅,材料结构致密。 相似文献
17.
18.
无水硫铝酸钙矿物的合成及形成机制 总被引:1,自引:0,他引:1
用化学试剂CaCO3,Al2O3,CaSO4·2H2O制备无水硫铝酸钙(C4A3 (S-))单矿物,借助化学分析法、X射线衍射、差热-热重分析及扫描电镜-能谱仪等研究了C4A3 (S-)矿物的形成机理.研究表明:C4A3 (S-)矿物分别是通过3种不同途径形成的;在煅烧温度低于1 100 ℃时,C4A3 (S-)矿物主要是由CaO,Al2O3,CaSO4直接通过固相反应形成;在煅烧温度高于1100 ℃时,C4A3 (S-)矿物是通过中间矿相七铝酸十二钙(C12A7)或铝酸一钙(CA)的形成而形成的. 相似文献
19.