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In this study, various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5. The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied. The results of XRD, TEM N2-adsorption-desorption, NH3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals, and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5. Catalytic cracking of n-dodecane (550 ℃, 4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance, with the improvement higher than 87% in the catalytic activities and 21% in the deactivation rate compared with untreated zeolites. This could be ascribed to their suitable pore structure, which enhanced the diffusion of reactant molecules in pores of catalysts. 相似文献
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Jianbo Zhang Huiquan Li Shaopeng Li Pengpeng Hu Wenfen Wu Qisheng Wu Xinguo Xi 《Ceramics International》2018,44(4):3884-3892
High-alumina coal fly ash (HAFA) is a special solid waste due to the existence of more than 45% alumina and 35% silica, which can be applied to prepare Al-Si series ceramics if the impurities can be removed and the Al/Si mass ratio can exceed 2.55 (Mullite: 3Al2O3.2SiO2). In this work, a new mechanical–chemical synergistic activation–desilication process is proposed, and the contents of different impurities can be lowered up to less than 1%, and the Al/Si mass ratio can be elevated from 1.26 to 2.71. Especially, the mechanism of this process is investigated in detail. The analysis of the mechanism shows that the decrease of Q4(3Al) and the increase of Q4(0Al), Q4(1Al), and Q4(2Al) improve amorphous silicate reactivity through synergistic activation, and the exposed amorphous Si-O-/Si-O-Si can be removed by OH- during the desilication process (desilicated ratio>55%), which help the fine mullite to exhibit excellent properties (bulk density > 2.85 g/cm3, apparent porosity < 0.5%) during the sintering process. Finally, this process not only decreases the pollution but also alleviates the shortage of Al/Si resources and promotes the clean development of coal-fired power generation. 相似文献
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铁矿阴离子捕收剂大多采用脂肪酸类捕收剂,工业上需要进行加温浮选才能确保浮选的效果。通过化学改性及复配合成了一种耐低温型铁矿捕收剂CY-20,并与高效速溶型抑制剂CYZ-20应用于山东某铁矿的低温反浮选试验。试验结果表明:CY系列药剂在浮选温度15℃下获得了精矿品位65.86%,回收率95.18%的浮选指标,与30℃时浮选指标基本相当。CY-20具有较强的耐低温性和选择性,可实现整个铁矿阴离子反浮选作业的常温操作,对矿山企业的节能减排、清洁环保生产具有重要的意义。 相似文献
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针对亚熔盐氧化铝流程中二氧化硅脱除的问题,提出采用钙铁榴石、水合碳铁酸钙和水合硫铁酸钙进行高浓环境介质分离;采用氧化物组成计算方法对此类化合物的Gibbs自由能进行了计算,在此基础上对脱硅剂合成反应进行了热力学研究;确定了不同脱硅剂的脱硅产物及其Gibbs自由能,对三种脱硅剂的脱硅能力进行对比,选择了最优脱硅剂。 相似文献
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A conceptual study has been carried out to convert geothermal water and condensate into a valuable industrial, agricultural or drinking water resource. Laboratory and field pilot test studies were used for the conceptual designs and preliminary cost estimates, referred to treatment facilities handling 750 kg/s of geothermal water and 350 kg/s of steam condensate. The experiments demonstrated that industrial, agricultural and drinking water standards could probably be met by adopting certain operating conditions. Six different treatments were examined. Unit processes for geothermal water/condensate treatment include desilication of the waters to produce marketable minerals, removal of dissolved solids by reverse osmosis or evaporation, removal of arsenic by oxidation/precipitation, and removal of boron by various methods including ion exchange. The total project cost estimates, with an accuracy of approximately ±25%, ranged from US$ 10 to 78 million in capital cost, with an operation and maintenance (or product) cost ranging from US$ 0.15 to 2.73 m−3 of treated water. 相似文献
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昆明冶金研究院研发了一种新型、高效的铝土矿正浮选捕收剂G7,为检验其在提高精矿指标、耐低温、易消泡脱水方面的优越性能,以云南某一水硬铝石型铝土矿为研究对象进行了选矿试验。结果表明,Al2O3和Si O2含量分别为67.51%和12.64%、铝硅比为5.34的铝土矿石在磨矿细度为-0.074 mm占90%、矿浆温度为3℃和20℃的情况下,采用2粗2精1扫、中矿顺序返回流程处理,分别可获得Al2O3品位和回收率为75.51%和89.13%,铝硅比为15.63的优质精矿和Al2O3品位和回收率为76.25%和90.28%、铝硅比为16.68的优质精矿。精矿指标分析和浮选过程观察表明,G7是一种性能优良、稳定、高效且适应性强的铝土矿浮选捕收剂。 相似文献