EU-1分子筛的合成及其在正己烷异构化反应中的催化性能

在不同硅铝比(n_SiO2/n_Al2O3)的合成凝胶(含纯硅凝胶)中引入晶种,合成了纯相的EU-1分子筛。研究了铝源、模板剂和晶种添加量对EU-1分子筛的结晶度、形貌尺寸等的影响;重点研究了不同硅铝比对样品结晶度、晶粒尺寸、酸性、比表面积和孔容等的影响。将合成结果绘制成了纯相EU-1分子筛的合成条件三元图,从三元图可看出,晶种法可显著扩大纯相EU-1分子筛的合成区域。将Pt/H-EU-1用于正己烷异构化反应,结果表明,该催化剂具有优异的正己烷异构化活性及稳定性,对异构烷烃有较高的选择性。     

引发剂对离子液体催化正己烷异构化反应的影响

由无水三氯化铝与盐酸三乙胺按照摩尔比2∶1合成了离子液体2AlCl3/Et3NHCl,并考察了其催化正己烷异构化的反应性能。发现离子液体2AlCl3/Et3NHCl可用于催化正己烷的异构化反应,但所需的反应时间较长。考察了引发剂正丁醇、异丁烯、异丁烷和异戊烷对离子液体催化正己烷异构化反应的影响。发现异戊烷作为引发剂时,正己烷的转化率为84.54%,液体收率为80.08%,异构烷烃的选择性为94.74%,达到了较好的反应效果。引发剂异戊烷的用量对异构化反应有着较大的影响,较优的引发剂用量为30%。添加异戊烷引发剂能明显提高离子液体催化正己烷异构化的反应速度,达到相似反应程度的反应时间可由6h缩短为45min。     

正己烷在不同硅含量SAPO-5分子筛上的裂化反应特征

正己烷在不同硅含量ＳＡＰＯ┐５分子筛上的裂化反应特征高大维黄彦孙铁杨胥微（吉林大学化学系，长春１３００２３）关键词磷酸硅铝分子筛，正己烷，裂化反应，酸中心１９８２年Ｗｉｌｓｏｎ等［１］首次报道了ＡｌＰＯ４－ｎ系列分子筛的合成工作，１９８３年Ｂｅｎｎｅ...     

纳米薄层MCM-22分子筛合成及其三甲苯异构化催化性能

采用十六烷基三甲基溴化铵(CTAB)和六亚甲基亚胺(HMI)组成双模板体系, 以气相二氧化硅为硅源, 在 150℃下动态原位合成了薄层的 MWW型 MCM-22分子筛纳米片, 并考察了 CTAB添加量对分子筛产物的影响。采用粉末 X射线衍射(PXRD)、扫描电子显微镜(SEM)、N₂吸附-脱附、氨气程序升温脱附(NH₃-TPD)、高倍透射电子显微镜(HRTEM)、吡啶红外(Py-IR)和 2, 6-二叔丁基吡啶红外(DTBPy-IR)测试方法对合成的分子筛样品进行表征。结果表明:采用双模板体系可以制备出 5~10 nm的薄层MWW型纳米片。同时, 通过偏三甲苯异构化反应对样品的催化性能进行了表征, 催化结果显示样品 d-MWW-4 %CTAB具有较好的催化性能, 其中偏三甲苯的质量转化率、均三甲苯质量收率及均三甲苯选择性分别为 34.97 %、22.42 %和 64.09 %, 这主要归因于薄层纳米片 MCM-22具有的较大外表面积和片层间形成的晶间介孔结构。     

纳米薄层MCM-22分子筛合成及其三甲苯异构化催化性能

采用十六烷基三甲基溴化铵(CTAB)和六亚甲基亚胺(HMI)组成双模板体系,以气相二氧化硅为硅源,在150 ℃下动态原位合成了薄层的MWW型MCM-22分子筛纳米片,并考察了CTAB添加量对分子筛产物的影响。采用粉末X射线衍射(PXRD)、扫描电子显微镜(SEM)、N₂吸附-脱附、氨气程序升温脱附(NH₃-TPD)、高倍透射电子显微镜(HRTEM)、吡啶红外(Py-IR)和2,6-二叔丁基吡啶红外(DTBPy-IR)测试方法对合成的分子筛样品进行表征。结果表明：采用双模板体系可以制备出5~10 nm的薄层MWW型纳米片。同时,通过偏三甲苯异构化反应对样品的催化性能进行了表征,催化结果显示样品d-MWW-4%CTAB具有较好的催化性能,其中偏三甲苯的质量转化率、均三甲苯质量收率及均三甲苯选择性分别为34.97%、22.42%和64.09%,这主要归因于薄层纳米片MCM-22具有的较大外表面积和片层间形成的晶间介孔结构。     

含铁微孔EU-1/ZSM-5复合分子筛的合成和表征

采用预置晶种法合成了含铁的微孔EU-1/ZSM-5复合分子筛,并采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、热重-微分热重(TG-DTG)、N₂吸附-脱附、紫外-可见吸收光谱(UV-vis DRS)、X射线吸收精细结构(XAFS)等手段进行了表征。结果表明,复合分子筛具有EU-1和ZSM-5的特征衍射峰,是两种晶相相互作用的分子分散晶相材料,微孔孔径较Fe-EU-1分子筛有所增大。随原始溶胶中铁的质量分数增加,复合分子筛具有的23.09°和23.94°处的特征衍射峰逐渐向低角度方向偏移;紫外-可见漫反射谱图中在220~245 nm出现了宽的吸收谱带;XAFS表征表明,1s→3d电子跃迁的弱吸收峰逐渐增强,同时在吸收边顶部出现的1s→4p吸收峰逐渐由宽变窄。合成工艺的最佳条件为,原始溶胶中铁的质量分数为0.075%~0.15%,晶种添加比例为15.0%~21.0%,晶种SiO₂/Al₂O₃物质的量比为50~60。     

室温离子液体催化正己烷异构化反应的研究

由无水三氯化铝与盐酸三乙胺按照不同摩尔比合成了具有不同酸度的室温离子液体,并考察了其酸性以及对正己烷异构化反应的催化性能。结果发现,随着离子液体合成时AlCl3比例的增大,离子液体的酸性增强,且离子液体2AlCl3/Et3NHCl对正己烷异构化显示出优良的催化性能。针对离子液体2AlCl3/Et3NHCl,考察了反应时间、反应温度和催化剂用量（剂油体积比）对正己烷异构化反应的影响。结果表明,反应条件对异构烷烃选择性的影响不大,但是对原料转化率、异构烷烃产率和液体收率有较大的影响。离子液体催化正己烷异构化的最佳反应条件,反应温度为50℃,反应时间为45min,剂油体积比为1∶1。     

Beta分子筛晶种法合成及其加氢脱氧性能

采用晶种法制备一系列Beta分子筛,考察了晶化温度和时间等因素对合成Beta分子筛的影响,并采用XRD、XRF、SEM、N₂物理吸附、TG-DSC等手段对产物进行表征,结果显示合成的Beta分子筛具有良好的结晶度、孔道结构、热稳定性和相近的硅铝比;通过对初始凝胶进行老化处理可加快Beta分子筛的晶化速率,产物晶粒尺寸变小、比表面积和孔容变大;在晶种-凝胶体系中加入少量有机模板剂,Beta分子筛的收率和热稳定性均有提升.NH₃-TPD和Pyridine-FTIR分析结果表明不存在有机模板剂的晶种-凝胶体系中合成的Beta分子筛催化剂有更多的总酸量和Brønsted酸的数量,使其在苯甲醚加氢脱氧反应中表现出高活性和环己烷选择性.     

CoAPO-11分子筛的合成、表征和催化性能： 1-己烯异构化反应

水热法合成了钴取代磷铝酸盐分子筛CoAPO-11，并采用了X射线衍射、扫描电子显微镜、红外光谱、紫外可见光谱以及氮气吸脱附等表征手段对合成的样品进行表征，并在合成的分子筛上进行1-己烯异构化反应评价，并考查了温度和空速对反应的影响。结果表明，在反应温度300℃及空速为2.4h－1CoAPO-11分子筛对1-己烯异构化反应具有较好的催化性能。     

Pt/SO42??ZrO2: The state of platinum and its relation with catalytic activity inn-hexane isomerization

Pt/SO₄ ²⁻−ZrO₂ calcined at 873 K shows the same catalytic activity forn-hexane isomerization as the calcined and reduced sample. A platinum reduction peak did not appear in the TPR profile and the presence of Pt⁰ was detected by XPS on the only calcined Pt/SO₄ ²⁻−ZrO₂. Nevertheless, this calcined material does not show hydrogen chemisorption and cyclohexane dehydrogenation activity.     

系列硅铝比纳米薄层ZSM-5分子筛的合成和表征

以自制不对称双子季铵盐表面活性剂为模板, 在水热合成体系中控制合成系列硅铝比纳米薄层ZSM-5分子筛.采用X射线衍射(XRD)、N₂吸附-脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)和²⁷Al魔角旋转核磁共振(²⁷Al MAS-NMR)对合成的样品进行了表征. 详细研究了晶化温度、晶化时间、结构导向剂(SDA)用量、碱度等对合成的影响和纳米薄层ZSM-5分子筛的形成过程. 结果表明: 分子筛硅铝比越高, 结构导向剂用量越大, 所需的晶化时间越短; 晶化温度越高, 晶化时间越短; 且不同硅铝比纳米薄层ZSM-5分子筛的形貌规整度、比表面积和介孔/微孔孔容比例随着硅铝比而变化.     

Transformation ofn-hexane over microporous molecular sieves: Studies over MeAPO-11 and MeAPSO-11

CoAPO-11, MgAPO-11, ZnAPO-11, COAPSO-11, ZnAPSO-11 and MgAPSO-11 samples were synthesized by hydrothermal methods and characterized. The samples were loaded with 0.5 wt.% Pt and tested for their catalytic activities in the isomerization ofn-hexane. All the samples exhibited catalytic activities and selectivities for isomerization comparable to that of SAPO-11. The selectivities for the different monomethyl and dimethyl isomers are rationalized on the basis of shape selectivity and acidities of different samples.     

Conversion ofn-hexane over Pt?Sn/γ-Al2O3 catalyst

Conversion ofn-hexane has been applied as a test reaction to study differences between the series of Pt−Sn/γ-Al₂O₃ catalysts obtainedvia different methods of preparation. Preliminary results of catalytic experiments have been compared with some changes occurring on the catalysts surfaces as the results of the preparation technique applied. It has been found that catalysts with the second metal (Sn) introduced to the support by the coprecipitation technique were much more stable in comparison to the catalysts where the tin component has been added by the impregnation method, however, we have not observed large differences in catalytic activity.     

不同硅铝比Cu-ZSM-5纳米片上N2O催化分解

以双季铵盐表面活性剂为模板剂,水热条件下合成了硅铝比(nSi/nAl)为18、26和95的ZSM-5沸石纳米片,采用离子交换方法制备了铜改性的ZSM-5纳米片样品,并测试了其催化分解N_2O性能。结合X射线衍射(XRD)、N_2吸附/脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)、透射电镜(TEM)、氢气程序升温还原(H_2-TPR)、氧气程序升温脱附(O_2-TPD)和原位红外漫反射光谱(CODRIFT)等表征结果 ,探讨了沸石硅铝比对于催化剂N_2O分解性能的影响及其原因。结果表明,ZSM-5纳米片硅铝比越低,CuZSM-5纳米片催化剂的活性越高。催化活性的提高归因于低硅铝比催化剂上Cu~+活性物种可还原性的增强和吸附氧脱附能力的提高。     

Effect of the nature of zeolite and modifying additives on the activity of zeolite-containing catalysts inn-butane isomerization

Isomerization ofn-butane on various types of zeolites (ZVM, ZVK, mordenite, and Y) modified with transition metals and cationic and anionic additives was investigated. Under the conditions studied, H-forms of zeolites are inactive. Pt-containing systems based on the H-form of ZVM (HZVM) are the most efficient catalysts forn-butane isomerization, and the yield of isobutane reaches 20–26 wt.% at a selectivity of 40–45%. Modification of this catalyst with Ga and Fe compounds or with an aqueous solution of HCl increases the selectivity with respect to isobutane up to 70–90%. Introduction of Zn²⁺ cations or F⁻ and SO₄ ²⁻ anions into the Pt-containing HZVM system decreases the selectivity and yield of isobutane due to the formation of very strong acidic centers on which disproportionation and hydrocracking ofn-butane mainly occur. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1281–1285, July, 1999.     

Effect of iridium loading on HZSM-5 for isomerization of n-heptane

The effect of iridium loading on the properties and catalytic isomerization of n-heptane over Ir-HZSM-5 is studied. Ir-HZSM-5 was prepared by impregnation method and subjected to isomerization process in the presence of flowing hydrogen gas. XRD and BET studies show that the presence of iridium stabilizes the crystalline structure of HZSM-5, leading to more ordered framework structure and larger surface area. TGA and FTIR results substantiate that iridium species interacts with OH group on the surface of HZSM-5. Pyridine FT-IR study verifies the interaction between iridium and surface OH group slightly increased the Bro¨nsted and Lewis acid sites without changing the lattice structure of HZSM-5. The presence of iridium and the increase of strong Lewis acid sites on HZSM-5 were found to bring an increase about 4.1%, 33.2% and 11.8% in conversion, selectivity and yield of n-heptane isomerization, respectively.     

Zinc-containing zeolite catalysts for ethane aromatization prepared by solid-state modification

Solid-state modification was used to prepare zinc-containing zeolite catalysts based on pentasils with different framework SiO₂/Al₂O₃ ratios. The catalysts were studied by X-ray diffraction analysis and IR spectroscopy. The activity and selectivity of the Zn—pentasil systems prepared by the solid-state modification and impregnation methods were compared in the aromatization of ethane. The active and stable zeolite catalysts modified by transition metal ions can be obtained by the topochemical method.