硅改性ZSM—5沸石分子筛的酸性,孔径和择形催化性能的研究

在不同条件下用各种硅改性剂对ＺＳＭ－５沸石分子筛进行改性，并将其用于催化乙苯歧化生成对二乙苯的反应。实验结果表明，在合适条件下用ＳｉＣｌ４对ＺＳＭ－５改性后，可以获得高性能形选催化剂。硅改性可以有效地消除催化剂外表面酸中心，并能对分子筛孔道进行微调。根据反应结果和反应物在催化剂中的扩散系数判断，当改性后催化剂的孔道半径与ＮａＺＳＭ－５沸石孔道半径相近时，其催化选择性最佳。     

TiCl4处理分子筛催化氧化苯乙烯

通过气相ＴｉＣｌ４对多种分子筛进行处理，用Ｈ２Ｏ２对苯乙烯的氧化反应作探针反应，考察了所得分子筛的催化活性，发现用ＺＳＭ－５制备的催化剂的催化性能最好，得到苯乙烯的转化率可达～１２％生成苯乙醛和环氧苯乙烷的选择性可达～５５．９％，并用ＩＲ对用于ＴｉＣｌ４处理过的ＺＳＭ－５进行了表征，证实了钛原子进入ＺＳＭ－５沸石骨架，生成了钛硅分子筛。     

ZSM－5型分子筛对正丁烯选择异构化反应的催化作用

报导了ＺＳＭ－５型分子筛催化剂对正丁烯选择异构化反应的催化性能，利用ＸＲＤ、ＳＥＭ、ＩＲ等方法对催化剂进行了表征，并应用原位红外技术对反应分子丁烯－２在催化剂表面上的吸附，反应行为进行考察．催化剂性能评价结果表明ＺＳＭ－５型分子筛催化剂对此反应具有较好的催化活性和选择性．用碘对其进行改性，可有效地改善催化剂的催化性能．     

沸石分子筛选择吸附焦化苯中的噻吩

对Ｘ、Ｙ、Ｍ、ＺＳＭ－ ５、Ｓｉｌｉｃａｌｉｔｅ－Ⅰ沸石分子筛选择吸附焦化苯中噻吩的性能进行了考察,结果表明：ＺＳＭ－ ５ 和Ｓｉｌｉｃａｌｉｔｅ－Ⅰ分子筛具有明显的选择吸附性能。通过对ＺＳＭ－ ５ 分子筛进行Ｃｕ２ ＋ 离子交换及表面硅烷化处理改性,能在一定程度上提高选择吸附性能,并认为沸石分子筛选择吸附性能与表面羟基（ＳｉＯＨ、ＳｉＯＨＡｌ） 的酸性及沸石孔道特征有密切的关系。     

HZSM－5改性的研究

ＨＺＳＭ－５改性的研究张谦和，何瑞德，胡杰南（中国科学院山西煤炭化学研究所太原０３０００１）关键词ＨＺＳＭ－５，改性，酸性，吸附，扩散自从中孔ＺＳＭ－５沸石分子筛问世以来，许多文献报道了用改性ＨＺＳＭ－５催化剂可使烷基苯烷基转移过程中表现出高对位选择...     

铁硅酸盐分子筛乙苯氧化脱氢催化性能研究：I.催化剂的表征及反应温…

本文合成了五种不同Ｓｉ／Ｆｅ比的Ｆｅ－ＺＳＭ－５分子筛，并进行了离子交换改性。ＸＲＤ和ＩＲ谱测试均表明Ｆｅ进入了分子筛骨架。用连续流动法考察了反应温度、ＥＢ／Ｏ２比对乙苯氧化脱氢活性的影响。结果表明，在８２３Ｋ和ＥＢ／Ｏ２＝１的条件下苯乙烯有最大收率。     

不同分子筛载体对CO加氢产物分布的影响

研究了几种小孔分子筛ＺＳＭ－５，ＨＹ，ＮａＹ及β担载ＺｒＯ２对Ｃ加氢反应的催化作用，并就产物的分布情况与担载ＺｒＯ２的硅铝中孔分子筛进行了对比研究。其中中孔分子筛分别用季铵盐和一级胺为模板剂，在水热条件和常温常压下合成；并用ＢＥＴ，ＸＲＤ，ＳＥＭ等手段表征了它们的孔道和骨架结构。另外，考察了碱金属Ｋ＾２＋，Ｎａ＾２＋对催化剂催化性能的影响。     

铁硅酸盐分子筛乙苯氧化脱氢催化性能研究Ⅰ．催化剂的表征及反应温度、原料气比例对活性的影响

本文合成了五种不同Ｓｉ／Ｆｅ比的Ｆｅ－ＺＳＭ－５分子筛，并进行了离子交换改性．ＸＲＤ和ＩＲ谱测试均表明Ｆｅ进入了分子筛骨架．用连续流动法考察了反应温度、ＥＢ／Ｏ＿２比对乙苯氧化脱氢活性的影响．结果表明，在８２３Ｋ和ＥＢ／Ｏ＿２＝１的条件下苯乙烯有最大收率．     

不同制备方法对Cu-ZSM-5沸石分子筛上NO分解反应活性的影响

不同制备方法对Ｃｕ┐ＺＳＭ┐５沸石分子筛上ＮＯ分解反应活性的影响＊韩一帆汪仁（华东理工大学工业催化研究所，上海２００２３７）关键词Ｃｕ－ＺＳＭ－５沸石分子筛，一氧化氮，催化分解，直接粘混法，离子交换法如何减少各类污染源所排放的氮氧化物（ＮＯｘ）对环境...     

IR和NH_3－TPD表征固态反应制备的Zn－ZSM－5丙烷芳构化催化剂

以固态反应制备了Ｚｎ改性的ＺＳＭ－５系列催化剂，用脉冲微反技术评价了丙烷在上述催化剂上的反应活性和芳构化选择性，用吡啶吸附ＩＲ和ＮＨ＿３－ＴＰＤ对催化剂改性前后的酸性及分布的变化进行了系统的表征，对固态反应制备Ｚｎ－ＺＳＭ－５的机理进行了讨论。还考查了固态反应条件对Ｚｎ￣（＋＋）迁移到分子筛孔道内并与其强Ｂ酸Ｈ￣＋发生交换作用的影响，找到了最佳的制备条件及最佳的Ｚｎ含量。     

Redistribution Mechanism of Chloromethylsilanes Catalyzed by HZSM-5 with Big and Small Apertures

The disproportionation to produce(CH_3)_2SiCl_2 can convert CH_3SiCl_3 and(CH_3)_3 SiCl wastes into treasure. In this paper, B3 LYP/6-311++G(3 df, 2 pd) basis set was used to calculate the mechanism of disproportionation, reaction catalyzed by 7 T cluster HZSM-5 with small aperture and 24 T cluster HZSM-5 with large aperture. The results showed that the activation energies for the rate-determining step of the reaction catalyzed by 7 T and 24 T HZSM-5 were 362.06 and 220.05 k J/mol, respectively. In combination with the structural analysis, activation energy analysis and LOL analysis were carried out for 7 T and 24 T HZSM-5. The obtained results show that the 24 T HZSM-5 with large aperture is good for disproportionation reaction compared to 7 T HZSM-5 with small aperture.     

多级结构ZSM-5沸石分子筛的合成及其Mo基催化剂在甲烷无氧脱氢芳构化中的应用

以经盐酸预处理的碳纳米管为第二模板,在不添加其它有机溶剂的情况下,仅通过控制晶化条件,即采用变温水热晶化法合成具有多级结构的ZSM-5分子筛.通过x射线衍射、红外光谱测试、透射电镜和N2吸附对合成的分子筛进行了表征,结果表明,该合成分子筛呈近球形,是由纳米棒自组装形成的具有多级结构的亚微米球.该分子筛改性后用于甲烷无氧脱氢芳构化反应,显示出良好的催化性能,甲烷转化率最初达到19%,反应至24 h时甲烷转化率仍保持在10%左右,并且保持了较高的芳香物选择性(达到50%以上).     

硅烷化处理的纳米ZSM-5的结构表征及催化性能

采用多次浸渍法和化学反应沉积法对纳米HZSM-5分子筛外表面进行了硅烷化处理,考察了改性后纳米ZSM-5对甲苯歧化的催化活性.采用改进的Hammett指示剂法和吡啶吸附红外光谱研究了催化剂的酸性位,采用X射线衍射和29Si MASNMR对催化剂的结构进行了表征.研究结果表明,硅烷化处理降低了纳米ZSM-5酸性位的浓度,从而降低了纳米ZSM-5的催化活性.硅烷化处理还减少了纳米ZSM-5中Si的Q4物种,降低了纳米ZSM-5的相对结晶度,同时硅烷化处理产生了脱铝作用.骨架铝含量的减少导致催化剂的酸性位减少,催化活性降低.     

Distribution of copper- and nickel-containing modifier components in the pore space of HZSM-5 zeolite

The distribution of copper- and nickel-containing components in the pore space of HZSM-5 zeolite was quantitatively studied. It was found that the detailed distribution of a modifier in the micropore and mesopore volumes of the zeolite depends on both the chemical nature of the modifier and the conditions of supporting and the regime of M²⁺ polycondensation in the pore space of the zeolite. The experimental data on the low-temperature adsorption of nitrogen on Cu(n)ZSM-5 catalysts can be interpreted as the result of the partial filling of the zeolite micropore space (10 vol %) and the finest mesopores with D < 3 nm with the modifier. In the case of Ni(n)ZSM-5 catalysts, the penetration of the modifier into zeolite channels (micropores) in detectable amounts was not found, and it was arranged in mesopores on the surface of zeolite crystallites. The reason for differences between modifier distributions in the pore structure of the zeolite was explained from the standpoint of different structures of copper and nickel polyhydroxo complexes in impregnating solutions after polycondensation. It was found that, in the Cu(n)ZSM-5 and Ni(n)ZSM-5 catalysts, the modifier component contained copper and nickel only in a doubly charged state and mainly octahedral oxygen environments. In this case, three-dimensional nanoparticles or coarsely dispersed particles of CuO were not detected in the pore space of the support, whereas the presence of a small amount of sufficiently large NiO crystals with a coherent-scattering region of 80–100 nm was detected in Ni(n)ZSM-5, and these crystals occurred on the surface of zeolite crystals. It was found that the apparent density of a copper-or nickel-containing component arranged in the pore space of the zeolite was lower than the density of the bulk CuO and NiO phases by a factor of ～3 and 4, respectively, because of the size effect.     

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。     

ZSM-5沸石结晶度对乙苯叔丁基化对位选择性的影响(英文)

Highly crystalline ZSM-5 zeolites are important for para-selective alkylation of alkyl aromatics, because they carry few external acid sites for isomerization of p-dialkyl products. Such zeolites (Si/Al = 25, 50, and 75) were synthesized in a fluoride medium between pH 4 and 6. Their crystallinities, crystal sizes, and surface areas were higher than those of a commercial ZSM-5 zeolite. Their para selectivities in alkylation were tested for vapor-phase tert-butylation of ethylbenzene between 200 and 400 °C. As expected, all the catalysts showed more than 90% para selectivity. At 300 °C, ethylbenzene conversion decreased in the order ZSM-5(25, commercial) > ZSM-5(25) > ZSM-5(50) > ZSM-5(75). The catalysts had weak, medium, and strong acid sites, but all the acid sites of ZSM-5(75) were weaker than those of ZSM-5(25) and ZSM-5(50). The high activity of commercial ZSM-5 was caused by its strong acid sites being stronger than those of the synthesized zeolites. Although the activity of the commercial catalyst was higher than those of the present catalysts, the selectivity for 4-t-butylethylbenzene (4-t-BEB) was low. The optimum feed ratio (ethylbenzene:t-butyl alcohol) was 2:1 and the feed rate was 1.65 h?1 for high ethylbenzene conversion and 4-t-BEB selectivity. Time-on-stream studies showed slow catalyst deactivation. Highly crystalline ZSM-5 zeolites are therefore better than a commercial zeolite for para-selective alkylation of alkyl aromatics. They do not require much post-modification for high para selectivity. A fluoride medium is therefore better than an alkaline medium for obtaining highly crystalline para-selective ZSM-5 zeolites.     

以天然矿物为全部硅铝源低成本绿色合成ZSM-5分子筛的研究

ZSM-5分子筛被广泛地应用于催化、吸附分离、离子交换和绿色化工等领域,但目前其合成主要是以无机化学品为硅铝源,从源头来看是非绿色化的过程.我们以热活化的硅藻土和亚熔盐活化的累托土为全部硅铝源,通过调变两种矿物的加入比例调变合成体系的硅铝比,在水热合成体系中制备ZSM-5分子筛.系统地考察模板剂用量、碱度、投料硅铝比、晶化时间等合成条件对产物结构和性质的影响,并对在最优条件下合成的ZSM-5分子筛的物化性质进行了详细地表征,结果表明：以天然矿物为全部硅铝源可以合成出具有较高结晶度、晶粒尺寸约为4 μm的六面体挛晶形貌的ZSM-5分子筛,该分子筛比商业ZSM-5分子筛具有更高的水热稳定性和更优的加氢异构性能.     

Alkylation of Ethylbenzene with Methanol on HY,HM and HZSM-5 Zeolite

The alkylation of ethylbenzene with methanol on various zeolites has been studied at atmospheric pressure, 300–500 °C and with ethylbenzene/methanol = 3 mol/mol in a fixed-bed, integral-flow reactor. The catalytic activity decreased in the order HZSM-5 > HY > HM. The optimum conditions for the formation of ethyltoluene were HY zeolite, 400 °C and W/F = 4.1 g-cat h/g-feed. The catalyst decay rate increased in the order HZSM-5 << HY < HM; coking of the zeolite increased the fraction of para-isomer in the ethyltoluenes. On HZSM-5 modified with alkaline earth metal, the conversion of ethylbenzene decreased with concomitantly increased selectivity of para-ethyltoluene especially evident in cases of magnesium and calcium (> 93% para-selectivity). These results are interpreted in terms of diminution of both the strong acid sites and the pore size of zeolites. For the reaction on HY at 400 °C, the reaction paths were determined; the ethylbenzene reacted via alkylation, disproportionation and dealkylation with initial selectivities 84.7%, 13.1% and 2.2%, respectively.     

HZSM—5沸石内外表面酸,孔大小和择形催化性能的研究

用吡啶、2,4-二甲基喹啉及NH_3吸附的TPD法测定了HZSM-5沸石的内、外表面酸量和酸分布,用环己烷吸附速度和吸附量表征孔大小,以乙苯歧化和对二乙苯异构化作研究择形催化反应.结果表明,HZSM-5外表面酸约占总酸量的20％,内、外表面酸均为非均匀分布.强酸位是对二乙苯和乙苯裂化的活性中心,而对歧化和异构化反应生成对位异构体的选择性影响不大.间二乙苯主要在内表面酸中心上生成,而对二乙苯在外表面酸位上异构化不是主要途径.对位选择性的提高与环己烷吸附速度减小有很好的对应关系,而与酸量变化关系不大.虽然中强和弱酸位对对位选择有一定影响,但影响对位选择性的主要因素是沸石的孔径大小.     

ZSM-5／Silicalite-1核壳分子筛含氟水热体系的合成及表征

以圆柱形ZSM-5为核,用柠檬酸对其外表面进行预处理后,在含氟壳层晶化体系中二次生长合成核壳分子筛.通过X射线衍射、扫描电镜、透射电镜、N2吸附及氨程序升温脱附对分子筛进行了表征,并以甲苯歧化和1,3,5-三甲苯裂化为探针反应对分子筛性能进行了考察.结果显示,产物是以ZSM-5为核、silicalite-1纳米晶为壳的两相复合微孔分子筛材料;在含氟体系中ZSM-5外延生长出了致密壳层;全硅壳层的覆盖度约达到97%,核壳分子筛的外表面酸位随之减少,但基本保持孔道内的酸性。