杂原子分子筛ZrBSrALPO4—5的合成结构及催化性能的研究

我们用热水合成法合成了一种锆-硼-硅磷铝分子筛，通过化学分析，测定晶胞参数及用XRD，MAS NMR方法进行表征，证实了锆-硼-硅原子进入了分子筛骨架，并且具有和AIPOR-5相似的结构；用IR，NH3-TPD表征方法测出了它们的酸性，测定结果表明，它具有L-酸性，测定结果表明，它具有L-酸和B-酸中心，以中等强度酸为主，在苯与烯烃烷基化反应中表现出良好的催化活性和长寿命并且对2-位和3-位苯的烷基化反应具有高选择性，有可能替代HF成为一种环境友好的新型催化剂。     

杂原子磷铝分子筛BSiAPO-5的合成结构及催化性能的研究

用水热合成法合成了一种硼-硅磷铝分子筛,通过化学分析、测定晶胞参数及用XRD,MAS—NMR方法进行表征,证实了硼、硅原子进入了分子筛骨架,并且具有和AIPO4-5相似的结构;用IR,NH3-TPD表征方法测出了它的酸性,测定结果表明,它具有L酸和B酸中心,以中等强度酸为主。在苯与烯烃烷基化反应中表现出良好的催化活性和长寿命,并且对2-LAB和3-LAB具有高选择性,有可能替代HF成为一种环境友好的新型催化剂。     

杂原子磷铝分子筛上异丁烷和丁烯烷基化反应

用水热合成法合成了一种锆—硼—硅磷铝分子筛,通过化学分析,测定晶胞参数及用XRD、MAS NM方法进行表征,证实了锆—硼—硅原子进入了分子筛骨架,并且具有和AlPO4 5相似的结构;用IR、NH3 TPD表征方法测出了它们的酸性,测定结果表明,它具有L酸和B酸中心,以中等强度酸为主。在异构烷烃与烯烃的烷基化反应中表现出良好的催化活性,并对TMP和DHM具有高选择性,有可能替代HF成为一种环境友好的新型催化剂。     

杂原子分子筛ZrBSiAlPO4-5上长链烯烃与苯的烷基化的研究

合成了一种锆－硼、硅磷铝分子筛，它具有和AlPO4-5相似的结构，用XRD，IR，NH3－TPD等方法作了表征，酸性的测量表明，它具有L－酸和B－酸中心，以中等强度酸为主，在苯与烯烃烷基化反应中表现出良好的催化活性和长寿命，讨论了催化剂的酸性与烷基化反应活性的关系，有可能替代HF成为一种环境友好的新型催化剂。     

改性NaY分子筛上多乙苯和苯烷基转移反应性能

为了提高烷基转移催化剂性能性,以不同骨架硅铝比的NaY分子筛为原料,利用"两交-水热-焙烧"后改性工艺得到了一系列USY分子筛。通过X射线衍射(XRD)、N_2-物理吸附、扫描电镜(SEM)、氨气程序升温脱附(NH_3-TPD)、吡啶吸附红外光谱(Py-IR)等表征手段研究了各USY分子筛的骨架硅铝比、孔结构特征以及酸性质,考察了各USY分子筛上苯与多乙苯烷基转移反应性能。结果表明:以骨架硅铝比为5.9的NaY分子筛为原料进行水热处理改性,有利于保持微孔结构且制得的USY分子筛比表面积和介孔量大、所含强B酸中心比例较高(B酸/L酸比为1.01),提高了活性位的可接近性及扩散能力,而且强B酸中心为苯与多乙苯烷基转移反应提供比较充足的活性位。在反应温度170℃、反应压力3 MPa、苯与多乙苯质量比2、质量空速为3.3 h~(-1)的实验条件下,二乙苯转化率和三乙苯转化率分别达到了67%和55%以上,乙苯选择性达到了99%以上。因此进一步调变NaY分子筛的合成工艺,合成具有较高骨架硅铝比的Y型分子筛可提高烷基转移催化剂的活性。     

β/MCM-41的制备及其在烷基化反应中的催化性能

用水热合成二步晶化法制备β/MCM-41中微孔复合分子筛,用XRD、N₂的吸附-脱附法和IR等方法进行表征,结果表明,合成的复合型分子筛同时具有中孔与微孔结构。在苯与长链烯烃烷基化反应中表现出良好的活性、选择性,有可能替代HF成为一种环境友好的新型催化剂。     

HF/USY催化合成长链烷基苯的研究

对USY分子筛进行了HF改性。XRD表征结果表明,改性后的催化剂基本保持了原有USY分子筛的晶型结构,并且分子筛与HF部分发生作用。选择3种结构和孔径大小不同的分子筛催化剂USY、HY和HPWA/SiO₂-Al₂O₃,在相同反应条件下,以苯和十六碳烯为原料考察了烷基化反应性能,并分别考察了催化剂对苯与十四碳烯、十六碳烯以及十八碳烯烷基化反应的催化性能。结果表明,HF/USY催化剂对苯与长链烯烃烷基化反应具有良好的催化性能。     

新型HZSM-5分子筛合成及催化苯、甲醇烷基化反应研究

采用水热合成法和离子交换法,以四丙基氢氧化铵为模板剂,合成了多级孔HZSM-5分子筛。采用XRD、NH3-TPD、N2物理吸附等手段对HZSM-5分子筛进行了表征。结果表明,该分子筛具有较大的比表面积和适量的酸性活性位。苯、甲醇烷基化反应的研究表明,与普通HZSM-5分子筛相比,该分子筛上苯的转化率提高了约5%,催化剂寿命有大幅提高。     

核壳ZSM-5分子筛合成及其催化苯与甲醇烷基化性能

为了提高苯与甲醇烷基化中苯转化率及产物选择性,利用球磨-母液重结晶的方法得到小晶粒ZSM-5分子筛,然后在十六烷基三甲基溴化铵(CTAB)辅助下制备了以介孔二氧化硅为壳,以小晶粒ZSM-5分子筛为核的核壳结构分子筛。采用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N_2物理吸附、NH_3程序升温脱附(NH_3-TPD)和红外光谱(IR)等方法表征了催化剂的物化性质,并在固定床反应器中考察了催化剂的催化性能。结果表明:该方法成功合成了微-介孔联通良好的核壳结构分子筛,且有效覆盖了核层分子筛外表面酸位。在苯与甲醇烷基化反应中,苯转化率提高了9.92%,乙苯选择性下降了2.77%,同时二甲苯及对二甲苯选择性有所提高,核壳结构分子筛催化性能的提升主要归因于其独特的孔道结构和酸性分布。     

制备方法对锆硅分子筛的催化性能影响

分别以水热法(DHT)、干胶法(DGC)和溶胶-凝胶法(Sol-Gel)合成了锆硅杂原子分子筛,采用XRD、TPD、SEM、TEM、FT-IR、N_2吸附-脱附等对分子筛样品的晶相结构、表面形貌、比表面积、孔径分布以及表面酸性进行表征。结果表明,水热法制备的锆硅杂原子分子筛特征峰明显,具有较高的结晶度,分子筛以微孔为主,并具有较多的酸中心和较大的比表面积,在α-蒎烯异构化反应中表现出较好活性和较高的柠檬烯选择性。     

Synthesis and Characterization of a SiAION Glass

Homogeneous SiAION glasses containing up to 1 wt% nitrogen were synthesized via a pressureless method with a controlled quench rate and structurally investigated using ²⁷Al and ²⁹Si magic-angle spinning nuclear magnetic resonance (MAS NMR), Raman, and infrared (IR) spectroscopies. Minor changes occur with the incorporation of nitrogen into the aluminosilicate glass structure as evidenced by modifications to spectra of a nitrogen-free aluminosilicate glass. The ²⁷Al MAS NMR spectrum of the SiAION glass shows the existence of aluminum in 4-,5-, and 6-coordination to oxygen. The ²⁹Si MAS NMR spectra show a distribution of silicon sites in 4-coordination to oxygen. Raman and IR spectra of the SiAION glass show additional features due to incorporation of nitrogen in the structure compared with spectra of nitrogen-free aluminosilicate glasses.     

Local Structure of xAl2O3· (1 −x)NaPO3 Glasses: An NMR and XPS Study

A series of x Al₂O₃· (1 − x )NaPO₃ glasses (0 ≤ x ≤ 0.275) were prepared and characterized by magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and by X-ray photoelectron spectroscopy (XPS). ²⁷AI MAS NMR spectra reveal that: at low alumina contents ( x < 0.125), Al is in dominantly octahedrally coordinated Al(OP)₆ structural environments; in glasses with x > 0.125, Al(OP)₄ environments are increasingly favored; and at x = 0.275, most Al is tetrahedrally coordinated. 5-coordinated Al environments also appear to be present. Variations in the ³¹P MAS NMR spectra are consistent with bonding between neighboring P and Al polyhedra. Quantitative changes in the oxygen bonding, determined from the O 1 s spectra obtained by XPS, also reflect these structural changes. The effects of alumina content on the relative concentration of nonbridging oxygen (PO⁻) are quantitatively described by a simple structural model derived from the MAS NMR data. The thermal expansion coefficients and glass transition temperatures are shown to be sensitive to these structural changes.     

铝源前驱体对离子热法合成磷酸铝分子筛的影响

以离子液体1-乙基-3-甲基-咪唑溴盐为溶剂和模板剂,选用不同的铝源,在常压下合成AlPO4-11分子筛. 考察了在不同铝源条件下,物料配比、晶化时间和晶化温度对合成AlPO4-11分子筛的影响. 产物通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)等表征手段进行了表征. 结果表明铝源性质的不同导致了合成规律和合成机理的不同. 以异丙醇铝为铝源合成分子筛时,所需最佳P/Al比为3/1,分子筛的晶化速率较慢;而以碱式乙酸铝为铝源合成分子筛时,物料的P/Al摩尔比相对较低(1.5/1),分子筛的合成具有更快的晶化速率.     

Characterization of the amorphous phases formed during the synthesis of microporous material AlPO4-5

We have used several solid-state NMR techniques in conjunction with powder X-ray diffraction (XRD) and Raman spectroscopy to characterize the structure of the intermediate amorphous phases of AlPO₄-5 molecular sieve synthesis. The evolution of the gel phases as a function of crystallization time was followed by ³¹P and ²⁷Al magic-angle spinning (MAS) NMR to obtain information on the local environments of Al and P atoms and by powder XRD to detect the long-range ordering of the gel samples. We have utilized ²⁷Al/³¹P double-resonance techniques such as heteronuclear correlation spectroscopy (HETCOR) to select the ³¹P–O–²⁷Al bonding connectivities and transfer of populations by double-resonance (TRAPDOR) to obtain information regarding the degree of condensation for P sites in the amorphous phases. The ¹H → ³¹P cross-polarization (CP) was used to identify the P sites with hydroxyl groups attached. Raman spectroscopy was also employed to follow the evaluation of the pore system. The ¹³C CP MAS spectra provide information regarding the chemical environment of template molecule in the gel. The work shows that a combination of the above-mentioned techniques can provide more detailed information on the structure of amorphous phases formed during hydrothermal synthesis.     

Epoxidation catalysts derived from introduction of titanium centers onto the surface of mesoporous aluminophosphate: Comparisons with analogous catalysts based on mesoporous silica

Titanium/AlPO materials were prepared by grafting a titanium alkoxide (titanium isopropoxide) onto a mesoporous aluminophosphate. The structures of the surface-bound titanium species were investigated by UV–vis, FTIR, MAS NMR, and XANES/EXAFS spectroscopies. The titanium anchoring occurs by reaction between the alkoxide precursor and surface Al–OH and P–OH groups of the AlPO support. The titanium species exist in isolated tetrahedral coordination environments, and as oligomerized species. The catalysts prepared are selective and active for the liquid-phase epoxidation of cyclohexene in the presence of TBHP. The observed activities and selectivities were comparable with those obtained for similarly prepared titanium/SBA-15 samples of similar Ti content (but higher BET surface area).     

Nature of Alumina in Phosphate Glass: II, Structure of Sodium Alurninophosphate Glass

We have used ²⁷Al and ³¹P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to describe quantitatively the relationships between the composition, structure, and properties of glasses in the Na₂O.Al₂O₃.P₂O₅ (NAP) system. In general, the glass properties (evaluated in part I) are most sensitive to changes in Al coordination. ²⁷ Al MAS NMR spectra reveal that octahedrally coordinated Al is most abundant in glasses with O/P ratios less than 3.5, the pyrophosphate structural limit. Tetrahedrally coordinated Al is most abundant in glasses with O/P greater than 3.5. Decreasing Al(OP)₆/Al(OP)₄ ratio generally correlates with decreasing glass transition temperature and refractive index. The compositional dependence of glass structure and properties can be qualitatively understood using a crystal chemical model based on oxygen charge balancing by the different Al and P moieties.     

Local Structure of Alkaline-Earth Boroaluminate Crystals and Glasses: II, 11B and 27Al MAS NMR Spectroscopy of Alkaline-Earth Boroaluminate Glasses

¹¹B and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra of alkaline-earth boroaluminate glasses show that the structure of these glasses are far more complicated than previously thought. The relative concentrations of 3- and 4-coordinated boron vary as found by previous investigators using continuous-wave NMR methods, but the ²⁷Al NMR spectra indicate the presence of Al in 4-, 5-, and 6-fold coordination, in contrast to previous assignments. Analysis of the data based on local charge balance considerations provides a qualitative model that correctly predicts compositional variations of the NMR peak intensities and ²⁷Al chemical shifts for a wide range of boroaluminate glass compositions.