几种分子筛的转晶和混晶的控制及单一晶体的优化合成

 以六亚甲基亚胺作模板剂，在配料比一定的情况下，详细考察了反应温度和反应时间对MCM－22，ZSM－5，ZSM－35和丝光沸石分子筛成晶的影响．结果表明，MCM－22的最佳合成温度在低温区，ZSM－35易在提高反应温度或延长反应时间时形成，而作为中间相的ZSM－5和丝光沸石则在反应温度与反应时间合理匹配时才能以单一相生成．同时，探讨了晶种的加入对产物晶相的影响．在特定的温度和时间区间，能够合成出比例可控的ZSM－35＋MCM－22混晶，ZSM－5＋ZSM－35混晶和ZSM－35＋丝光沸石混晶，并从分子筛孔道和结构单元的特点出发，就转晶发生对温度和时间的依赖性作了解释．     

ZSM-5／MOR复合分子筛催化剂对混合C4烃转化反应的催化性能

以ZSM-5/丝光沸石(MOR)复合分子筛为催化剂,对混合C4烃的催化转化反应进行了评价,并采用程序升温脱附和原位红外光谱技术对ZSM-5/MOR的酸性进行了表征. 结果表明,与ZSM-5相比, MOR具有很低的催化活性,但ZSM-5/MOR复合分子筛具有较高的催化活性,随着ZSM-5/MOR复合分子筛中ZSM-5含量的增加, C4烃转化率稍有升高;在C4烃转化率大致相同的情况下,乙烯和丙烯的总选择性比较接近,但苯和甲苯的总收率却快速升高. 随着ZSM-5/MOR复合分子筛中ZSM-5含量的增加,弱酸和中强酸的酸量逐渐减少,强酸的酸量有所增加. 由于ZSM-5/MOR复合分子筛中MOR对ZSM-5起到分散作用而产生更多的L酸中心,且此L酸中心处于分子筛的外表面而具有较高的能量,导致苯和甲苯的总收率升高.     

不同结构扩孔分子筛催化MTP反应行为及表面积炭物种表征

采用TEAOH溶液处理MFI结构ZSM-5分子筛、MWW结构MCM-22分子筛,NaOH溶液处理TON结构ZSM-22分子筛、CHA结构SSZ-13分子筛得到四种结构的扩孔分子筛。在反应温度480℃、反应压力0.1 MPa、甲醇与水质量比1∶1、甲醇质量空速1.5 h~(-1)的条件下,考察了四种扩孔分子筛的甲醇制丙烯(MTP)催化性能,并采用XRD、N_2吸附-脱附、NH_3-TPD、TG、UV-Raman和GC-M S等方法表征催化剂的物化性质及M TP反应2 h后的分子筛积炭性质。结果表明,四种分子筛扩孔改性后均出现介孔,其中,T-ZSM-5分子筛在MTP反应中寿命最长;T-MCM-22分子筛寿命次之且失活速率慢;而一维孔道结构N-ZSM-22分子筛和八元环尺寸较小的N-SSZ-13分子筛均失活迅速。受拓扑结构和孔道扩散的影响,MTP反应2 h后,分子筛积炭量增加的顺序为T-ZSM-5N-ZSM-22T-MCM-22N-SSZ-13且可溶焦分子质量随积炭量增加而增重,即从五甲基苯增重到菲、芘等多环芳烃。     

Effect of zeolite pore morphology on solvent-less alkylation of benzene with 1-hexene

In an attempt to convert the carcinogenic benzene which is almost restricted for its use in gasoline, alkylation reaction with olefin 1-hexene has been conducted on various zeolites. Four zeolites having different pore topology and pore size have been applied as solid acid catalysts for effective production of alkylate in a liquid phase, solvent-less low temperature reaction. The textural properties of all the four zeolites (ZSM-5, MOR, BEA, HY) have been characterized for crystal morphology by TEM, crystal structure by XRD and FTIR, BET for surface area, N₂ sorption for porosity and TPD for acidity. Among the zeolite, BEA possessed high surface area (600.61 m²/g) and enhanced meso pores volume (0.3956 cm³/g) as compared to other zeolite samples. The performance of BEA was also observed to be superior in the liquid phase alkylation of benzene with 1-hexene in a batch reactor under autogenous pressure without using any solvent. At the optimum reaction conditions, the benzene conversion was 86.6 wt% and 3-Phenylhexane, 2-Phenylhexane yield were about 47.9 wt% and 38.7 wt% respectively on this catalyst. The BEA also exhibited longer time-on-stream and reusability performance, thus offers an attractive route for converting benzene into valuable (3-Phenylhexane, 2-Phenylhexane) alkylate product useful for the manufacturing of fine chemicals, dyestuff, detergents and scents.     

MCM-22型分子筛的合成及其用于生产异丙苯的催化性能

MCM-22 molecular sieve was first reported by Rubin et al[1] in Mobil Company.Similar to ZSM-5 zeolite, MCM-22 belongs to the category of medium pore zeolites.However, it possesses unique structural features[2] that have not been demonstrated before. The structure of MCM-22 was resolved by Mobil scientists using high resolution microscopy and X-ray diffraction analysis. It is found that MCM-22 consists of two independent and non-interconnecting channel systems, each accessible through 10-ring apertures. One of these pore systems is composed of uniform circular 10-ring pores about 0.6 nm. The other is composed of 12-ring egg-shaped supercages with inner free diameter of 0.71 nm and inner height of 1.82 nm. Usually the zeolite crystallizes as thin sheets or plates of stocked layers. Therefore, MCM-22 has been actively studied and this peculiar zeolite may have potential applications in the petrochemical and petroleum industries in the near future, including reactions such as disproportionation[3], catalytic cracking of hydrocarbons[4], aromatic/ethylene alkylation[5], isoalkane/olefins[6] and methanol/olefins alkylation[7] etc.     

十元环分子筛在甲醇芳构化反应中催化性能的研究

合成了ZSM-5、ZSM-22、EU-1、MCM-22和ITQ-13具有十元环孔道结构的5种分子筛,研究了分子筛结构、酸性分布等因素对其在甲醇芳构化反应中催化性能的影响。研究表明,不同结构分子筛的形貌、酸性及孔径均存在较大差异,进而影响了其在甲醇制芳烃反应中的催化活性和稳定性。研究的5种分子筛中,ZSM-5表现出最佳的芳构化活性,芳烃收率达34.8%,MCM-22芳烃收率约为21.9%,而其他3种结构的分子筛催化剂基本未表现出甲醇芳构化活性。通过添加具有芳构化性能的Ga物种对ZSM-5和MCM-22进行改性,可显著提升芳烃收率,Ga/ZSM-5上芳烃收率达到40.8%,Ga/MCM-22上芳烃收率可提高到27.1%。另外,采用TG/DTA、GC等方法研究了失活催化剂的积炭情况,发现分子筛结构对积炭量、积炭组成及积炭分布存在显著影响。     

ZSM-5/ZSM-57复合分子筛催化剂上混合C4烃的催化转化反应

以ZSM-5/ZSM-57复合分子筛为催化剂, 考察了其对混合C4烃催化转化的反应性能. 采用氨程序升温脱附(NH3-TPD)和吡啶吸附傅立叶变换红外(FT-IR)光谱技术表征复合分子筛的酸性质. 结果表明, 当复合分子筛中ZSM-5的含量较低时, 比ZSM-5具有更高的催化活性及乙烯和丙烯选择性, 这是因为此时复合分子筛酸强度较高、酸量较多, 且小孔ZSM-57有利于乙烯和丙烯的择形反应. 而当复合分子筛中ZSM-5的含量较高时, 具有较高的苯和甲苯选择性, 其原因可能是其孔结构及共晶生长时的结构匹配性对芳构化反应有利.     

丙烯醚化合成二异丙醚催化剂研究

比较了Hβ沸石、树脂、ZSM-5沸石等常用于丙烯醚化合成二异丙醚（DIPE）催化剂的性能，考察了助剂对Hβ沸石孔结构、酸度及催化活性的影响。结果表明，Hβ沸石上丙烯醚化合成DIPE的催化活性优于ZSM-5沸石，而树脂催化剂可催化丙烯水合生成异丙醇（IPA）反应。TiO2、ZrO2、碱土金属、稀土元素和VB族元素均使Hβ沸石的B酸中心减少，L酸中心增多。总酸量较大、L酸中心较多的催化剂，更有利于DIPE的生成。孔性质对催化剂活性的影响较小。TiO2可以大幅度提高DIPE选择性和时空产率，对提高丙烯转化率并无贡献。ZrO2可提高DIPE选择性、丙烯转化率和DIPE的时空产率，副产丙酮，且C6杂质较多。同时添加一种碱土金属、一种稀土元素和一种VB族元素制备的Hβ沸石催化剂具有较好的合成DIPE活性，在165℃、7.0 MPa、水/丙烯摩尔比0.5和LHSV 0.5h－1时，DIPE的初始收率达到39%。运转1 000 h后，DIPE收率仅下降了3%。     

Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite

ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N₂ adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.     

乙炔、丙烯在多种分子筛上的吸附和脱附性质

在80℃下研究了ZSM5、13X、Y、MOR、5A、SAPO34等多种分子筛和常见载体上乙炔和丙烯的吸附和脱附性能。结果表明，乙炔和丙烯在SiO2、γ-Al2O3上不吸附，而与分子筛存在较强的相互作用。对于同类型的分子筛，两者的饱和吸附量均随分子筛硅铝比的增大而减小。在同一种分子筛上，以摩尔计的丙烯吸附量均明显高于乙炔。在80℃改性β分子筛上乙炔和丙烯饱和吸附量可分别达到0.11mmol/g和4.89mmol/g，该结果明显高于文献报道的结果。     

Investigation and Modeling of the Hydrothermal Stability of Technically Relevant Zeolites

The dense-structured zeolites of types ZSM-5 (MFI) and mordenite (MOR) of different SiO₂/Al₂O₃ moduli are relatively stable under treatment by liquid water for 72 hours up to 513 K. The open-structured zeolites of types Y in dealuminated modification (FAU) and beta (BEA) undergo strong decomposition in the same range. For these two sample types a mathematical model for the decomposition of the zeolite framework is established that takes into account the influence of modulus as well as temperature. Here the kinetic of the solid phase reaction is a superposition of two different mechanisms described by the Monod equation. Dedicated to the late of Wolfgang Schirmer.     

不同模板剂合成具有介微结构的ZSM-5分子筛及其甲醇制丙烯性能

分别采用四丙基氢氧化铵(TPAOH),十六烷基三甲基溴化铵(CTAB)和N-十八烷基-N'-己基-四甲基-1, 6-己二铵(C_18-6-6Br₂)作为模板剂,合成了具有不同介微结构的纳米ZSM-5分子筛(NZ),介孔ZSM-5分子筛(MZ)和纳米薄层ZSM-5分子筛(NSZ).对合成的样品进行X射线衍射(XRD),扫描电子显微镜(SEM), N₂吸附-脱附和氨程序升温脱附(NH₃-TPD)表征,并与传统微孔ZSM-5分子筛(CZ)对比.结果表明,样品的介孔孔容和外表面积大小的顺序为NSZ > MZ > NZ > CZ,强/弱酸之比的顺序为CZ > MZ > NZ > NSZ.在甲醇制丙烯(MTP)反应中,催化剂的介微结构特征影响MTP反应的产物选择性及稳定性,丙烯和总低碳烯烃选择性随着介孔孔容的增加而增加, NSZ样品具有最高的丙烯选择性(47.5%)及总低碳烯烃选择性(78.4%).此外,介孔的引入能适当延长催化剂的寿命,具有适宜酸性质的NZ样品的催化寿命最长(200 h).     

不同B,Al分布对ZSM-5分子筛的甲醇制丙烯反应性能的影响

本文设计了两个系列的硼改性ZSM-5分子筛:一步法合成的B-Al-ZSM-5系列分子筛和两步法合成的Al-ZSM-5@BZSM-5核壳分子筛。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、扫描透射电子显微镜面扫(STEM mapping)、N——2物理吸附脱附、氨气程序升温脱附(NH3-TPD)、1,3,5-三异丙基苯(TIPB)裂解等表征发现,两个系列的样品中B1-Al-ZSM-5和Al@B1-ZSM-5,B2-Al-ZSM-5和Al@B2-ZSM-5以及B3-Al-ZSM-5和Al@B3-ZSM-5分别具有相似的织构性质、强弱酸量、酸强度和比例,以及不同的B、Al元素分布和酸分布。我们用这两个系列样品对比研究不同的强弱酸分布-强弱酸均匀分布和梯度分布对甲醇制丙烯(MTP)反应性能的影响。通过研究发现,强弱酸均匀分布的样品具有更高的丙烯选择性,归因于更低的整体强弱酸密度;而强弱酸梯度分布的样品具有更长的MTP反应寿命,归因于外表面上更低的强酸密度和更高的弱酸密度。     

三种不同拓扑结构的分子筛在甲醇制烯烃反应中的性能对比

采用XRD、SEM、N₂吸附-脱附、NH₃-TPD研究了3种不同拓扑结构的分子筛SAPO-34、Al-ITQ-13和ZSM-5分子筛的孔结构、酸性分布对其甲醇制低碳烯烃中反应性能的影响.结果表明,SAPO-34对乙烯具有最好选择性,可达52.3%;ZSM-5和Al-ITQ-13则对丙烯具有良好的选择性可达50.3%和50.0%,丙烯选择性相当,但兼顾乙烯时,Al-ITQ-13较ZSM-5高,可达18.4%.3种分子筛反应性能的差异主要是其拓扑结构的不同引起的.孔道结构越小则越有利于小分子产物的生成,具有八元环结构的SAPO-34分子筛对小分子乙烯具有最高的选择性,而同时具有九元环和十元环结构的Al-ITQ-13由于孔道中含有一套九元环结构,使其与ZSM-5分子筛相比,在丙烯选择性相当的情况下,小分子产物乙烯明显增加.     

Synthesis of nano/micro scale ZSM-5 from kaolin and its catalytic performance

Nano/micro scale ZSM-5 zeolites were synthesized by using natural kaolin as raw material. The effect of particle size on the catalytic performance of ZSM-5 zeolite for the methanol to olefins conversion was evaluated in a fixed-bed reactor. The results indicated the crystal size had a significant effect on the catalytic stability and the products distribution. ZSM-5 with nanosize showed better tolerance to coke formation, longer catalytic lifetime, and higher selectivity to propylene. The selectivity to propylene on nanosized ZSM-5 was on average 4.5% higher than on the submicron sample and 10% higher than on microsized ZSM-5. After the reaction was conducted for 20 h the ZSM-5 catalyst synthesized from kaolin showed longer lifetime and higher propylene selectivity than the sample synthesized with chemical materials The reason can be explained by the occurence of such elements as Fe, P, and especially Ti.     

Direct amination of isobutylene over zeolite catalysts with various topologies and acidities

The atomically economic and green chemical reaction of direct amination of isobutylene to tertbutylamine, particularly under the relative mild reaction conditions available for future industrial use,was carried out over zeolite catalysts possessing different topological structures, from one dimensional to three dimensional pore system, and from small 8-member ring pore(MRP) to medium 10 MRP and further to large 12 MRP zeolites, to disclose the relationship between the zeolite properties/topologies and their amination performance systematically under the mild reaction conditions. It was discovered that the pore structure and the acidities of zeolite catalysts played crucial roles in the isobutylene amination process, and suitable pore diameter(larger than 0.5 nm or with large side pockets/cups in the outside surface) and a certain number of mid-strong acid sites are indispensable to catalyze the amination reaction,while too strong acid strength was not conducive to the process of isobutylene amination. Among them,zeolites with topologies of BEA, MFI, MEL, MWW and EUO exhibited good amination performance, with which the isobutylene conversion was higher than 12.61%(46.42% of the equilibrium conversion) under the studied mild reaction conditions. Due to the good amination performance and the large adjustable Si/Al_2 ratio range, ZSM-5 was selected to further study the effect of acidity on the amination performance systematically under the mild reaction conditions, and the activity-acidity relationship in the amination process was disclosed: the amination activity(isobutylene conversion) had a linear correlation with the amount of mid-strong B acidity under the studied conditions over ZSM-5 catalyst, which can provide guidance for further developing high-efficient amination catalyst under mild reaction conditions available for future industrial use.     

Alkylation of benzene with propylene over MCM-36: A comparative study with MCM-22 zeolite synthesized from the same precursors

Pillared layered MCM-36 zeolite was prepared from MCM-22 precursor with polymeric silica as pillaring agent. Both MCM-36 and MCM-22 zeolites are very active for the alkylation of benzene with propylene, and MCM-36 shows higher selectivity to cumene compared with MCM-22 zeolite.     

Synthesis and Characterization of ZSM-5/β Co-Crystalline Zeolite

ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have been synthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO2, silica sol as the source of aluminum and silica, respectively, and TEA as the template under controlled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM, BET and NH3-TPD. The reaction activity of toluene alkylation was investigated with a mixture of toluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite. It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5 and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/β co-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. In addition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/β co-crystalline zeolite shift 23 ℃ to lower temperatures and the acid amount of its strong acid is 3% more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest content of xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolite has better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 and their physical mixture.     

CuCoMn-zeolite双功能催化剂转化生物质基合成气制取液态烃

选用四种不同的分子筛（SAPO-34, ZSM-5, Y, MCM-41）与CuCoMn（高醇合成组元）构成双功能催化剂,利用N2吸脱附、H2-TPR、XRD、NH3-TPD等表征了催化剂的结构性质. 研究了催化剂在生物质基合成气一段法制取液态烃燃料的应用. 相比于CuCoMn催化剂,加入分子筛的双功能催化剂均不同程度地提高了液体烃燃料的选择性及收率,且收率按顺序递减呈CCM-ZSM-5〉CCM-SAPO-34〉CCM-Y〉CCM-MCM-41. 同时,共沉淀法制备的CuCoMn-ZSM-5 （20wt%, Si/Al=100） 具有最佳的CO转化率（76%）及液体产物收率（30%）. 相比于CuCoMn氧化物,双功能催化剂的比表面及孔容均得到提高. CCM-ZSM-5具有适中的微孔尺寸和中等强度的酸性,增加CCM-ZSM-5中ZSM-5含量或降低ZSM-5中的Si/Al比,均有利于提高酸性位的数量,主要是较弱的酸性位. 而共沉淀法制备的CCM-ZSM-5具有更好的金属分散性及还原性能.     

Supercritical CO2 as a superior solvent for the cyclization of diallylmalonate catalyzed by palladium-containing zeolites

Palladium-containing zeolites catalyze the cycloisomerization of diethyl diallylmalonate to dimethylcyclopentenes. When the reaction is carried out in toluene, the performance of the palladium catalyst depends on the pore size of the zeolites. At 60 °C, palladium adsorbed on large pore size Beta zeolite (pore size ∼7.4 Å) is more active than medium pore size ZSM-5 (pore size ∼5.4 Å). This lower activity of ZSM-5 compared to Beta is attributable to the restricted diffusion of reagent and products through the ZSM-5 channels as compared to Beta zeolite. However, due to the gas-like diffusion characteristic of the supercritical state, the activity of ZSM-5 increases and becomes identical to that of Beta zeolite using supercritical CO₂ as medium.