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SAPO-34 分子筛合成实例

SAPO-34 分子筛合成实例. 解决的基础问题 Si 原子是如何进入分子筛骨架的 如何控制 Si 原子在分子筛骨架中的分布. 结构 & 组成. 催化 性能. 分子筛的 合成与制备. Al(1Si). Al(1Si). Al(3Si). Al(4Si). Higher Si/Al. Stronger acidic sites. XRD spectra of as-synthesized samples. Crystallization curve of SAPO-34. IR results.

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SAPO-34 分子筛合成实例

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  1. SAPO-34分子筛合成实例 • 解决的基础问题 • Si 原子是如何进入分子筛骨架的 • 如何控制 Si 原子在分子筛骨架中的分布 结构 & 组成 催化 性能 分子筛的 合成与制备 DICP

  2. Al(1Si) Al(1Si) Al(3Si) Al(4Si) Higher Si/Al Stronger acidic sites

  3. XRD spectra of as-synthesized samples DICP

  4. Crystallization curve of SAPO-34 DICP

  5. IR results DICP

  6. Assignment of the IR bands in framework vibration region of the as-synthesized samples DICP

  7. Relative content curve of template in the as-synthesized samples Influence of crystallization on the composition of solid samples DICP

  8. 31P NMR of the gel samples in the first steps of the crystallization process • The stirred mixing gel of the raw sources (silica sol, pseudoboehmite, orthophosphoric acid and water) • The stirred mixing gel of a. and template (TEA). • The b. gel after aging (the initial state of the crystallization). DICP

  9. 27AlMAS(a), 31P MAS(b) and 29Si CP/MAS(c) NMR spectra of as-synthesized samples in the earlier stage of crystallization a b c DICP

  10. 27Al MAS NMR spectra of calcined and dehydrated samples in the earlier stage of crystallization DICP

  11. Changes of the Al(IV), P(IV) and Si(IV) relative content (a) and relative proportion (b) of the as-synthesized samples with crystallization time (b) relative proportion DICP (a) relative content

  12. SAPO-34晶化机理模型 相对结晶度 ~80% 重排 聚合 晶粒以 Si(4Al) 方式生长(2.5h) 初始凝胶 (0h) 形成 晶核 (0.5h) 晶粒生长 Si 直接参与 ~80%Si 直接进入骨架 Si(nAl) n=0-4 结构形成 (26h) Si 取代P 2Si 取代 Al+P DICP

  13. 4.分子筛的基本性质 • 基本特点 • 多孔晶体，规整孔道结构 • 大比表面积 • 结构多样性 • 组成多样性 • 高热稳定性，水热稳定性 • 基本性质 • 离子交换性质 • 吸附性质 • 固体酸碱性质 DICP

  14. DICP

  15. DICP

  16. DICP

  17. DICP

  18. DICP

  19. DICP

  20. 5.分子筛的表征 • XRD：晶相，晶胞参数，晶体结构 • 电子显微镜：晶貌，组成 • 吸附－脱附：比表面积，孔径，孔容、 酸碱性等 • 红外光谱（IR)：－OH；酸碱性质；骨架；表面物种 • NMR：结构微环境分析；酸碱性质 • 热重－差热：热稳定性，酸碱性，吸附（脱附）性质，积碳分析 DICP

  21. 注意：XRD图随组成也有变化 DICP

  22. 去除模板剂前后XRD图有变化 DICP

  23. Sum of peak heights (unknown) % Crystalinity = Sum of peak heights (standard) XRD测定结晶度 • 一般测定8个主峰即可 • 也可用于测定杂晶相对结晶度 DICP

  24. XRD测定Si/Al比 • 晶粒必须大于0.3微米 • 组成变化引起晶胞参数变化，XRD呈现规律性 • 可以测定Si/Al • 判断晶体中是否有不均匀Al分布 DICP

  25. HZSM-5 ％Al＝16.5－30.8 DICP

  26. IR法测定Si/Al 组成规律变化会体现在IR光谱中 只对特定体系适用 DICP

  27. DICP

  28. 分子筛酸性的测定 • 酸碱中和（指示剂法） • TPD • IR • 1H-NMR • 31P-NMR • TPD和IR最常用 DICP

  29. H-MAS-NMR spectrum of HY zeolite DICP

  30. IR spectra of HY zeolite without and with adsorbed pyridine  HY  HY+Pyridine (Lewis) (sodalite) (supercage) (B) DICP

  31. Pyridine adsorption on different zeolites samples DICP P.A. Weyrich, W.F. Holderich, Appl. Catal. A 158 (1997)145.

  32. Comparison of Various Acid Characterization Methods Method Acid Type Acid Amount Acid Strength Major Drawbacks Acid Location (Int./Ext.) Brønsted Lewis ─ + + Titration + + Accessibility ─ TPD (Bases adsorption) + + + ± Diffusion & Non-acidic adsorption IR (hydroxyls) + ─ ─ ─ + Sample preparation IR (Bases adsorption) + + + ± ± Sample preparation 1H NMR (hydroxyls) + ─ ─ ± + Water adsorption 31P NMR(TMP) + + ─ +(B) ─ (L) +(L) ─ (B) Volatile, Oxidization & Toxicity 31 P NMR (Phosphine Oxides) + + + + (B, L) + (B, L) Weaker basicity

  33. NH3-TPD of H-ZSM-5 Zhao et al., J. Phys. Chem. B, 106, 4462 (2002)

  34. 1H & 27Al MAS NMR of H-ZSM-5 Spinning Rate = 5.0 kHz Spinning Rate = 5.5 kHz

  35. Introducing the Players TMPO (Trimethylphosphine Oxide) Size ca. 0.55 nm TMP (Trimethylphosphine) Size ca. 0.55 nm TBPO (Tributylphosphine Oxide) Size ca. 0.82 nm ZSM-5 (10-MR)

  36. add TMPO/TBPO dissolved in CH2Cl2 723 K; 24 h H-ZSM-5 under N2 glovebox dehydration vessel agitated at RT; 12 h packing into MAS rotor Loaded Sample 31P MAS NMR CH2Cl2 evacuation under N2 glovebox 323 K Sample Preparation Procedures TMP Adsorption thermal decompositionof trimethylphosphine silver iodide complex onto the dehydrated H-ZSM-5 at 473 K TMPO (TBPO) Adsorption

  37. TMP / Brønsted acid site TMPO / Brønsted acid site Ionic Pair Complex Hydrogen Bonded Complex Interactions Between Probe Molecules and Brønsted Acid Sites Formation of TMPH+ complex Higher Acidic Strength O-H Bond Strength  31P Chemical Shift (downfield) Lunsford et al., J. Am. Chem. Soc., 107, 1540 (1985) Mueller et al., J. Phys. Chem. B, 102, 2890 (1998)

  38. B Spinning Rate = 7 kHz L CP/MAS Decoupling Without decoupling 31P MAS NMR (TMP/H-ZSM-5/26) Assignments -4 ppm: TMPH+/Brønsted acid sites -50 ppm: TMP/Lewis acid sites -62 ppm: PhysisorbedTMP Lunsford et al., JACS, 107, 1540 (1985) NOTE: Acid sites with different strengthscannot be differentiated !!

  39. HZSM-5/15 * * * * HZSM-5/26 * * * * * HZSM-5/75 * * * * * HZSM-5/15 (Partially hydrated) * * * * 150 120 90 60 30 0 Chemical shift (ppm) 31P MAS NMR (TMPO/H-ZSM-5) Mobile TMPO Spinning Rate = 10 kHz TMPO can probes both internal and external acid sites Upto five 31P resonance were observed @ 86, 75, 67, 63 and 53 ppm for TMPO/Brønsted  Increasing Si/Al Acidic Strength  No Lewis acid sites observed The newly observed 30 ppm peak can be ascribed due to mobile TMPO

  40. 64 48 (P) (a) TMPO 69 * * * * 70 58 (P) (b)TBPO 74 * * * * Correlation of Results Obtained from TMPO and TBPO Spinning Rate = 10 kHz Adsorption of TMPO and TBPO on Al-MCM-41 (Si/Al = 70; pore size = 2.54 nm) Mechanism of Acid Site Formation in Al-MCM-41 ? Mueller et al., J. Phys. Chem. B, 102, 2890 (1998) Zhao et al., J. Phys. Chem. B, 106, 4462 (2002)

  41. 31P MAS NMR of Crystalline TBPO

  42. Acid Properties of H-ZSM-5 Determined by 31P MAS NMR in Conjunction with ICP (1) refer to chemical shift difference w.r.t. crystalline TMPO (39 ppm) or TBPO (47 ppm). (2)Data in parentheses denote (Int., Ext.) acid concentrations in (0.05) mmol/g cat. (3) Assume 1:1 relation between adsorbate and Brønsted acid site. ICP probides concentrations of Al, Si and P.

  43. 31P NMR Chemical Shift Assignments for Various Catalysts Adsorbed with TMPO and TBPO

  44. Distribution of Acid Sites for Various Catalysts

  45. 6.分子筛的催化性能 • 分子筛的特点 • 多孔晶体 • 孔道结构规整 Shape selective effect • 比表面积大 High activity • 组成可调变性 • 酸、碱性可调 • 离子交换性 • 氧化还原性能 TS-1，?.. • 结构可调变性 • 据反应特点选择分子筛 DICP

  46. Shape-selective effect • 规整孔道结构使分子筛具有特殊的催化性能 • Reactant shape selectivity • Product shape selectivity • Reactant shape selectivity and product shape selectivity are strongly depending on crystal size and activity • Restricted transition state shape selectivity • Restricted transition state shape selectivity is independent of crystal size and activity, but depends on pore and cavity diameters and on zeolite’s structures DICP

  47. Reactant shape selectivity Product shape selectivity DICP

  48. Reactant shape selectivity Dehydration of n- and iso-butanol on Ca-X and Ca-A DICP

  49. Product shape selectivity C5-C11，汽油 ZSM-5 MTG CH3OH SAPO-34 C2-C4，烯烃 MTO 改性ZSM-5 CH3OH ＋ toluene  p-xylene DICP

  50. Liquid Phase Alkylation of Naphthalene over Large Pore Zeolites R R Background PEN PBN 塑料 液晶中间体 --- 中法PICS项目 DICP

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