MAPO-5分子筛的合成、结构及其性质的研究

用水热法合成了磷酸镁铝分子筛(MAPO-5),以X射线衍射、电子探针、核磁共振及红外光谱等方法进行了结构分析,并测定了MAPO-5分子筛的晶胞参数、化学组成,同时对分子筛的吸附性能、热稳定性、酸性等进行了研究。证明镁进入了分子筛的骨架。     

高温离子热合成MAPO分子筛

在280℃条件下,以磷酸为磷源、异丙醇铝为铝源、乙酸镁为镁源、正二丙胺为结构导向剂,在溴化1-丁基-3-甲基咪唑鎓([BMIM]Br)离子液体中合成了系列MAPO分子筛。随着晶化时间的延长,出现了一个从MAPO-5到MAPO-11、进而到MAPO-25分子筛的转晶过程。这一符合Ostwald定律的转晶过程伴随着骨架密度的增加以及样品形貌和模板剂状态的变化。     

金属磷铝(MeAPO)分子筛的合成及催化活性

本文用水热法合成了MAPO-5、CoAPO-5、CoMAPO及MAPO-36四种分子筛。对新合成的样品进行了XRD、IR、SEM及原子吸收光谱分析。确认各样品皆为分子筛结构,初步证实金属Mg和(或)金属Co进入到分子筛的结构骨架。金屑磷铝分子筛比磷铝分子筛裂化活性提高很大,从分析产物C_3及C_4看出各样品的低催化活性对应于低的C_4/C_3·C_4/C_3值反映了分子筛的窄小空腔或弯曲通道。     

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。     

CdAPO-5的合成、结构及催化性能(Ⅱ)--有机模板剂与金属离子半径大小对晶相形成的影响

探讨了几种不同有机模板剂(二环己胺、二正丁胺、乙二胺、环己胺、TEAOH)对CdAPO-5分子筛晶相形成的影响,以及金属离子(Mn+)半径大小对取代AlPO4-5分子筛骨架中Al3+离子而形成MAPO-5分子筛晶体的影响.结果表明,TEAOH是合成CdAPO-5分子筛较合适的有机模板剂,合适形成金属磷酸铝分子筛的Pouling半径比(rn+M/r2-O)可大于0.73.     

水蒸气处理改性的SAPO-11分子筛催化合成2,6-二甲基萘的研究

采用水蒸气对SAPO-11分子筛进行改性.通过XRD、SEM、NH3-TPD以及N2吸脱附等表征手段对改性前后SAPO-11分子筛的结构、酸性进行表征,并研究了改性后分子筛催化合成2,6-二甲基萘反应性能的影响规律.结果表明,水蒸气处理使SAPO-11分子筛发生骨架脱铝,酸中心数量减少,比表面积和孔体积有所下降,从而使2,6-二甲基萘的选择性、2,6-二甲基萘与2,7-二甲基萘的比值及催化稳定性提高.     

含HF体系中SAPO-11分子筛的合成与表征

 在含HF体系中合成了SAPO-11分子筛,并采用X射线衍射、扫描电镜、低温氮物理吸附、红外光谱和吸附氨的程序升温脱附等手段对其进行了表征. 结果表明,相对于常规无HF合成体系,在HF体系中合成的SAPO-11分子筛样品结晶度提高,结晶速度加快,分子筛单晶增大,分子筛晶粒聚集体的粒径减小,比表面积降低,孔体积与平均孔径增大. 合成体系中加入HF后SAPO-11分子筛上B酸中心的总酸量和弱酸量降低,中强酸中心的比例有所提高,而L酸的酸量和酸强度无明显改变.     

纯相ZSM-11分子筛在双模板剂水热体系中的合成及表征研究(英）

在水热体系中利用双模板剂合成了纯相ZSM 11分子筛,并考察了合成条件的影响。同时利用多种表征手段对产品的物理化学性质进行了表征。     

ZSM—11型Zr—Si分子筛的合成研究

分别以硅溶胶为硅源、氧氯化锆为锆源、四丁基溴化铵的模板剂,采用水热晶化法合成了ZSM-11型的锆硅分子筛。用XRD和SEM等表征了分子筛的结构;考察了硅锆比、晶体温度、碱度、晶化时间、模板剂的用量等对分子筛形成过程的影响。结果表明,ZSM-11型的锆硅分子筛的形成受很多因素的影响,一般晶化温度为120-140℃、硅锆比高于20、碱度控制在4.7左右有利于分子筛晶体的生成,晶化时间一般为约48h,SEM照片显示所合成的Zr-ZSM-11分子筛为结晶完好的棒状晶体;EDX证实了Zr原子在分子筛中的存在。     

SAPO-11/Beta复合分子筛的合成及其异构化性能研究

以Beta分子筛为硅源通过水热合成法合成了SAPO-11/Beta复合分子筛,采用X射线衍射、N2物理吸脱附、扫描电镜、透视电镜-能谱分析、固体核磁及吡啶红外等方法对单分子筛、复合分子筛和机械混合分子筛的物化性质进行了表征.以正十二烷为模型化合物,在固定床反应器上考察了铂负载型分子筛催化剂的异构化性能.结果表明,复合分子筛的物理化学性质明显不同于单分子筛和机械混合分子筛,其呈现核壳结构,SAPO-11和Beta间存在化学作用,使得复合分子筛具有适宜的B酸分布.在正十二烷异构化反应中,复合分子筛催化剂的异构化性能优于单分子筛催化剂和机械混合分子筛催化剂,多支链异构体收率高.     

Synthesis and Characterization of Magnesium Substituted Aluminophosphate Molecular Sieves with AEL Structure

MAPO-11 molecular sieves were synthesized by hydrothermal methods. The influence of precursor of magnesium, Mg/Al ratio, synthesis temperature, synthesis time and the type of template on the formation and properties of MAPO-11 molecular sieves was examined. The samples were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric/differential thermogravimetric analysis (TG-DGA), etc. The results show that the shape and size of crystal were influenced by the precursor of Mg, the Mg/Al ratio and the type of template, and the TG-DGA analysis shows that MAPO-11 molecular sieves as-synthesized have poor thermal stability.     

Synthesis and Characterization of AlPO4-11 and MAPO-11 Single Crystals

The preparation of two types of molecular sieves AlPO4-11 and MAPO-11 is reported. The particle size of the latter is hundreds of microns, about 10 times larger than that of the former. The XRD, IR and DTA spectra have demonstrated that magnesium has been introduced into the framework of AlPO4-11. The successful preparation of large single crystal of MAPO-11 will open up a new area for the preparation of large molecular sieves crystals in the future. The large MAPO-11 crystal compound is a promising host for the host-guest assembly of composite materials.     

新型磷酸硅铝分子筛SAPO-53的合成与表征

以氢氧化已烷双铵(R(OH)2)为模板剂,采用水热条件合成了高结晶度的SAPO-53分子筛。并采用XRD、SEMEDX、FT-IR、MAS NMR、电泳仪、N2吸附-脱附、TG-DTG等手段对合成的分子筛进行表征。考察了硅铝比、磷铝比、模板剂的用量以及晶化时间等条件对合成SAPO-53分子筛的作用。29Si MAS NMR表明,Si主要以四配位形式进入了AlPO4-53的骨架中,SAPO-53相对结晶度先增加后开始缓慢下降,Zeta电位值先增加后保持不变,与以甲胺为模板剂合成相比,氢氧化已烷双铵的用量比甲胺减少了一半,同时缩短了晶化时间,降低了合成的难度。通过计算得到SAPO-53的表观生长速率大于成核速率,说明成核过程是速率控制步骤。     

Isomorphous substitution of Mn(II), Ni(II) and Zn(II) in AlPO-31 molecular sieves and study of their catalytic performance

Isomorphously substituted molecular sieves, MAPO-31, NAPO-31 and ZAPO-31, were prepared under mild hydrothermal conditions from gels containing sources of aluminium, phosphorus, appropriate metal and dipropylamine (DPA), presumably acting as a structure-directing template. They were characterized by XRD, FTIR, TGA, inductively coupled plasma (ICP), ESR, Brunauer, Emmett, Teller (BET) and diffusion reflectance spectroscopy (DRS) techniques. In the XRD, the peak at 2θ = 16.7° of the metal substituted AlPO-31 is more intense than that of pure AlPO-31 suggesting preferential occupation of the plane corresponding to it as compared to other planes. The O-H stretch in the IR spectra of the metal-substituted molecular sieves is blue-shifted with respect to the parent AlPO-31 molecular sieves possibly due to metal substitution. Theg values obtained from the ESR spectra of MAPO-31 and NAPO-31 also substantiate framework substitution. Ethylation of toluene was carried out between 300 and 450°C over the above catalysts as a model test reaction. The high toluene conversion over metal-substituted molecular sieves proves the isomorphic substitution of metal ions in the AlPO-31 framework.     

Product selectivity in methanol to hydrocarbon conversion for isostructural compositions of AFI and CHA molecular sieves

Isostructural molecular sieves based upon AlPO₄ and SiO₂ chemistry were made for comparison of catalytic selectivity. The AFI and CHA structures were compared with B and Al substitution of SiO₂ and Mg and Si substitution in the AlPO₄ case. The conversion of methanol to hydrocarbons was studied. Materials were characterized for acidity by NH₃ TPD and NH₃ microcalorimetry. Methanol conversion was carried out with products analyzed by GC-MS and spent catalysts by ¹³C MAS NMR. Borosilicate sieves have acidity too low to carry out this catalytic transformation. Other substituting components were successful but product selectivity seemed to be governed by geometric features of the sieves, rather than by variable acidity due to different types of lattice substitution. Products from small pore molecular sieves SAPO-34 and SSZ-13 were largely olefinic and comprised of C₅ and smaller. The large pore sieves, SAPO-5, MAPO-5, and SSZ-24, all produced aromatic-rich products. A considerable quantity of the recovered hydrocarbon was incorporated into penta- and hexamethylbenzene.     

Synthesis and Surface Acidity of MeAPO-5 Molecular Sieves

Metal substituted aluminum phosphate molecular sieves, MeAPO-5 (Me = Co, Mn, Fe(II), Fe(III), and Mg) were synthesized and characterized with X-ray diffraction and scanning electron microscopy. The acidity was determined by temperature programmed desorption of ammonia, Desorption peaks at around 200°C were observed for all the MeAPO samples studied. Additional desorption peaks at around 300°C were found in MnAPO-5, CoAPO-5, and MAPO-5. MnAPO-5, CoAPO-5, and MAPO-5 also show good activities toward the cracking reaction of cumene at 350°C, while Fe(II)APO-5 and Fe(III)APO-5 show some activity at 500°C. The order of the cracking activity correlates with the presence of strong acidic sites in MnAPO-5, CoAPO-5, and MAPO-5 as indicated by the TPD of ammonia.     

MgAPO-11分子筛的合成及Pt/MgAPO-11在正十二烷临氢异构化反应中的催化性能

 采用常规水热合成法合成了系列MgAPO-11分子筛,考察了晶化时间、 P/Al投料比和Mg源对MgAPO-11分子筛的物相、酸性以及Pt/MgAPO-11催化正十二烷临氢异构化反应性能的影响. 分别用X射线衍射、 X射线荧光光谱和NH3程序升温脱附测定了样品的晶相、 Mg含量和酸性质. 结果表明,合成条件影响着合成产物的晶相组成、 Mg含量及酸性质,从而影响到Pt/MgAPO-11在正十二烷临氢异构化反应中的催化性能. 反应结果显示, Pt/MgAPO-11催化剂的催化活性与MgAPO-11分子筛的强酸位数目密切相关. 较短的晶化时间、合成凝胶的P/Al摩尔比为1.0以及使用Mg(NO3)2为Mg源有利于提高MgAPO-11的强酸位数目,从而提高Pt/MgAPO-11的催化活性.     

Synthesis and crystal morphology control of AlPO4-5 molecular sieves by microwave irradiation

AlPO₄-5 molecular sieves have been synthesized by the hydrothermal and solvothermal reactions using triethylamine as a template, aluminum isopropoxide and orthophosphate as the aluminum and phosphorus resource under microwave irradiation. The influences of various experimental parameters, such as reaction time, reaction temperature and reaction power, have been systematically investigated. The morphology control of AlPO₄-5 molecular sieves was achieved by changing the dosage of solvent and HF to control the solvent polarity and control the nucleation respectively. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and so on. The results show that the aspect ratio of the AlPO₄-5 molecular sieves increases with the increase of the solvent polarity and with the increasing concentration of HF, the morphology of AlPO₄-5 molecular sieves changes from hexagonal plate to hexagonal rod.     

Lewis acid metal ion-exchanged MAPO-36 molecular sieve: Characterisation and catalytic activity

Magnesium aluminophosphate-36 (MAPO-36) molecular sieve was synthesised hydrothermally and subjected to wet ion-exchange with Fe³⁺, Zn²⁺, La³⁺ or Ce³⁺. They were characterised by using XRD, SEM, temperature programmed desorption (TPD) of ammonia and thermogravimetric analysis (TGA). The XRD patterns of ion-exchanged MAPO-36 exhibit similar features to that of MAPO-36, which revealed no structural degradation during ion-exchange. TPD (ammonia) showed selective ion-exchange of strong acid sites for Fe³⁺, La³⁺ and Ce³⁺ but not for Zn²⁺. Based on the results of TGA the actual species involved in the ion-exchange is suggested to be M(OH)₂⁺, which upon calcination converted to MO⁺ where M is Fe³⁺, La³⁺ or Ce³⁺. tert-Butylation of phenol was carried out in the vapour phase as a probe reaction to examine the catalytic activity of MAPO-36 and ion-exchanged MAPO-36 molecular sieves. The ion-exchanged catalysts were found to be more active than the parent MAPO-36 and also showed higher selectivity to 4-tert-butylphenol.