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以TiCl4为钛源合成钛硅分子筛 总被引:1,自引:0,他引:1
Since titanium silicalite-1 (TS-1) was first prepared by Taramasso et al[1] in 1983,the synthesis of TS-1 and its application in partial oxidation have become a hotspot in the zeolite catalytic field.For the traditional synthesis route of TS-1,the key problem is its costly price and severe synthesis conditions,which hamper its industrial application.To avoid using costly alkali-free tetrapropylammonium hydroxide (TPAOH) as a template,Müller et al[2] reported that TS-1 could be synthesized using tetrapropylammonium bromide (TPABr) as a template with ammonia as the base to adjust the basicity of the gel. 相似文献
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Nanosized zeolites have received considerable attention in the field of catalysis for their unique properties.When the crystal size of HZSM-5 is reduced to nanoscale,it exhibits higher catalytic activity,less coke and longer catalytic life in CH3OH conversion to hydrocarbons and C2H4 oligomerization[1]. 相似文献
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钛硅沸石的结晶动力学研究 总被引:8,自引:1,他引:7
在TPABr-正丁胺体系中合成了钛硅沸石TS-1, 研究了此体系中的结晶动力学,求出了不同温度下的成核速率、晶体生长速率及表观活化能. 还研究了晶种类型和用量对钛硅沸石晶化的影响. 结果表明,随着晶化温度的升高, TS-1成核诱导期缩短,成核速率及晶体生长速率加快; 加入晶种可明显缩短TS-1成核诱导期,并减小晶粒粒度; TS-1, M, ZSM-11和β沸石等均可作为晶种合成TS-1, 并存在一个最佳晶种用量; 不加晶种时TS-1成核活化能和晶体生长活化能分别为44.4和75.7 kJ/mol. 相似文献
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水热处理对MCM-22催化剂酸性、孔结构及甲苯/甲醇烷基化性能的影响 总被引:1,自引:0,他引:1
采用XRD, NH3-TPD, IR和低温氮气吸附等方法研究了分别以纯水蒸气和质量分数为6%的氨水蒸气处理MCM-22分子筛催化剂后, 其酸性和孔结构的变化, 并以甲苯、甲醇烷基化为探针反应考察了催化剂的催化性能. 研究结果表明, 在两种不同介质中和处理温度不高于400 ℃条件下, 催化剂的总酸量变化不大, 强酸中心有所增加; 处理温度高于500 ℃后, 催化剂的总酸量明显下降, 强酸中心基本消失; 经水热处理后, MCM-22分子筛催化剂中形成了孔径不均匀的二次孔, 平均孔径增大. 随着处理温度的提高, 催化剂的活性降低, 对二甲苯和邻二甲苯的选择性上升. 经500 ℃纯水蒸气处理5 h的MCM-22催化剂, 具有适宜的酸强度和酸类型分布, 有利于甲苯甲醇烷基化反应的进行, 且催化剂维持了较高的催化活性并具有一定的对位选择性(甲苯转化率和对二甲苯选择性分别29.22%和42.16%). 相似文献
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添加吐温40合成钛硅分子筛TS-1 总被引:3,自引:0,他引:3
以自制的四丙基氢氧化铵(TPAOH)水溶液为模板剂,采用在水热晶化合成体系中添加少量非离子表面活性剂——吐温40的方法,合成了钛硅分子筛TS-1,可以明显减少TPAOH的用量,而且在一天之内,即可得到纳米尺寸的TS-1。运用XRD、TEM、BET、FT-IR及UV-Vis等表征手段考察了TS-1的结构及物理性能,并以丙烯环氧化为探针反应,考察其催化性能,得到的结果表明,用这种方法合成的TS-1样品具有较高的结晶度和较大的比表面积,晶貌呈均匀的立方体状,颗粒尺寸在100 nm左右,并且样品中含有极少量锐钛矿型TiO2,其催化丙烯环氧化反应性能较好。 相似文献
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纳米分子筛ZSM-5的热稳定性研究 总被引:5,自引:0,他引:5
Nanosized ZSM 5 zeolite was synthesized by hydrothermal method and characterized by XRD and TEM techniques. The specific heat of the nanosized ZSM 5 zeolite was measured in the temperature range from 79 to 370 K, and its enhancement in specific heat was observed as compared with the corresponding microsized zeolite, indicating that the nanosized ZSM 5 zeolite possesses higher surface activity. The thermostability of the samples was determined by differential scanning calorimetric (DSC) and thermogravimetric (TG) techniques. The DSC results showed that, for the nanosized ZSM 5, a broad exothermic peak is observed from 1?300 K; for the microsized ZSM 5, the corresponding exothermic peak begins at 1?400 K, and a distinct phase transition can be observed at 1?620 K. The TG results showed that, for the nanozised ZSM 5, the maximum mass loss ratio is 6 9%, and two mass loss stages can be observed in the temperature ranges of 298~663 K and 923~ 1?273 K, respectively; for the microsized ZSM 5, the maximum mass loss ratio is 6 5% and it is more stable than the nanosized ZSM 5. 相似文献