超稳Y分子筛改性的研究进展

本文从超稳Y分子筛的制备与改性两个方面综述了超稳Y分子筛(USY分子筛)的研究进展,对改性的超稳Y分子筛的二次孔体积、比表面积、水热稳定性、酸量和酸强度等方面进行总结,并对USY分子筛改性研究的重点及发展方向进行了展望.     

脱铝超稳Y分子筛负载磷钨酸铯催化水解乙酸甲酯

采用两步浸渍法制备脱铝超稳Y分子筛(DUSY)负载磷钨酸铯(Cs_(2.5)PW)催化剂,用X射线衍射(XRD)、N_2低温吸附-脱附技术(BET)、傅立叶红外光谱(FT-IR)、扫描电镜(SEM)对催化剂进行表征,并考察了USY脱铝及负载量对DUSY/Cs_(2.5)PW在乙酸甲酯水解反应中催化剂性能的影响。结果表明,以DUSY为载体,Cs_(2.5)PW负载量为10%时,Cs_(2.5)PW高度分散,且保持了原有的Keggin结构,催化剂表现出较高的乙酸甲酯水解反应活性,而以USY为载体的催化剂活性低。在反应温度为328 K下,反应2 h,乙酸甲酯水解率为18.70%。催化剂重复使用6次后,乙酸甲酯水解率为15.56%,表明催化剂具有较好的稳定性。     

脱铝超稳Y沸石催化合成乳酸正丁酯

研究了脱铝超稳Y沸石催化乳酸与正丁醇的酯化反应,考察了催化剂硅铝化、催化剂用量、反应物配比和反应时间对酯化反应的影响。结果表明,在优惠反应条件下,反应在1 h内完成,酯收率达74％以上,催化剂可重复使用。     

超稳Y型分子筛的骨架硅铝比对甘油气相脱水反应的影响

以铵交换和高温水热处理法制备了不同硅铝比的超稳Y型分子筛（USY）,利用X射线衍射、扫描电镜、氮气吸附脱附和吡啶红外等技术对USY进行了表征。以USY为催化剂,考察了USY的骨架硅铝比对气相甘油脱水制丙烯醛的影响。X射线衍射和扫描电镜结果表明,铵交换和高温水热处理只是提高USY的硅铝比,相对结晶度略有降低,而对Y型分子筛的结构和形貌没有影响。氮气吸附-脱附和吡啶红外结果表明,随USY骨架SiO₂/Al₂O₃比提高,总酸量和B酸酸量逐渐降低,L酸酸量有所增多,介孔孔体积和平均孔径有所增大。气相甘油脱水反应结果表明,催化剂织构性质对甘油转化率和丙烯醛选择性的影响大于酸性的影响,因而SiO₂/Al₂O₃比为29的USY催化剂的反应性能最好,甘油转化率和丙烯醛收率分别达到了84.5%和51.8%。     

脱铝超稳Y沸石催化合成乳酸正丁酯

研究了脱铝超稳Y沸石催化乳酸与正丁醇的酯化反应 ,考察了催化剂硅铝化、催化剂用量、反应物配比和反应时间对酯化反应的影响。结果表明 ,在优惠反应条件下 ,反应在 1h内完成 ,酯收率达 74 %以上 ,催化剂可重复使用。     

脱铝超稳Y沸石催化环己醇脱水制备环己烯

研究了脱铝超稳Y沸石催化环己醇脱水制环己烯的反应 ,考察了催化剂硅铝比、催化剂用量、反应物配比、反应温度和反应时间对脱水反应的影响。结果表明 :在催化剂硅铝比为 1 0 99,催化剂用量为环已醇质量的 7 5% ,油浴温度为 1 80～ 1 90℃ ,反应 1h ,环已烯产率达 87 8% ,催化剂可重复使用。     

NaY分子筛离子改性和脱铝改性研究进展

NaY分子筛作为催化剂基础原料,是石油催化加工过程中应用最广泛的催化剂产品,拥有很强的催化活性、稳定性以及重金属污染抵抗性。本文介绍了NaY型分子筛离子交换改性和脱铝改性的研究进展及其作用机理,以及Y型分子筛超稳化改性后分子筛性能的变化。     

Y型分子筛的有机酸脱铝改性

利用有机酸对Y型分子筛进行改性,采用XRD、XRF、XPS和IR等对其进行表征,结果表明,分子筛经过离子交换降低钠含量,水热焙烧后,采用有机络合剂进行处理,更有利于得到结晶度高和非骨架铝含量低的分子筛;在相同柠檬酸或草酸比例下,采用柠檬酸处理的样品,其硅铝物质的量比和结晶度均高于草酸处理样品;有机酸处理有利于分子筛非骨架铝的脱除,尤其分子筛外表面非骨架铝的脱除,提高分子筛结晶度和硅铝物质的量比。m(柠檬酸)∶m(分子筛)=a∶1~(a+0.10)∶1时,晶胞尺寸变化不大;m(柠檬酸)∶m(分子筛)=(a+0.15)∶1时,分子筛晶胞进一步收缩,结晶度降低;随着柠檬酸比例增加,脱铝处理分子筛的B/L降低。     

脱铝超稳Y催化乙酸与β－苯乙醇酯化反应的研究

采用脱铝超稳Ｙ作为催化剂，甲苯作为带水剂，对乙酸与β－苯乙醇的酯化反应进行了研究。在最佳反应条件下，该反应可在４ｈ内完成，酯产率达９９％以上。该法操作简便，易于工业化生产。     

气相低浓度甲苯在超稳Y分子筛的吸附-脱附性能

为提高Y分子筛对可挥发性有机废气的选择性吸附能力,采用高温水热处理技术对NaY分子筛进行骨架脱铝制备超稳Y分子筛(USY),并在固定床反应器中考察了USY在水汽存在下动态吸附低浓度甲苯的性能。结果表明,随着USY分子筛骨架Si/Al比的增加,虽然其微孔孔体积和比表面积发生了下降,但形成了较多的中孔结构。并且骨架硅含量增加后,USY对非极性的甲苯分子选择性吸附能力明显增加,当Si/Al为22左右,在相对湿度50%下,单位面积甲苯吸附量要比水吸附量大5.6倍。热重脱附研究表明,经过改性后,甲苯脱附温度可从NaY的300℃下降到超稳Y分子筛的160℃,具有优良的热再生性能。     

USY分子筛的改性及应用进展

USY分子筛由于其突出的物化性质在石油化工领域得到广泛应用,并表现出优异的催化裂化性能。随着技术的进步,对USY分子筛改性以及拓宽USY分子筛的应用范围成为研究热点。介绍USY分子筛的改性及应用进展,在改性方面,总结对USY分子筛的酸碱改性、金属改性以及多种方法混合改性等改性方式;在应用领域,讨论USY分子筛在有机物的合成、生物质降解与环保、无机物的选择性催化以及在电化学方面的应用。     

USY分子筛的改性研究进展

主要从超稳分子筛(USY)的制备与改性技术两个方面介绍了USY分子筛的改性研究进展.对USY分子筛进行改性,调变其结构和表面酸性,可以达到改善其催化性能的目的.常用的改性方法有:负载阳离子及氧化物、酸处理、再脱铝(生成DUSY)等,并对以后USY分子筛的改性进行了展望.     

氢氟酸改性USY分子筛催化合成乙基叔丁基醚的研究

以氢氟酸改性USY为催化剂,乙醇和叔丁醇为原料,合成乙基叔丁基醚(ETBE)。与未改性USY和国产强酸性阳离子树脂D005相比,氢氟酸改性USY的催化作用显著。分别考察了催化剂负载量、反应温度和反应时间等因素对醚化反应的影响。最佳操作条件为:n(乙醇)∶n(叔丁醇)=2∶1,原料质量为10 g,催化剂用量为1 g,USY分子筛上氢氟酸负载量6%,反应温度120 ℃,反应时间3 h。最佳操作条件下乙基叔丁基醚的产率为52.46%,叔丁醇转化率为55.83%,选择性为95%。     

USY分子筛上苯与多仲丁苯烷基转移反应

在微型固定床反应器上研究USY分子筛对苯与多仲丁苯烷基转移反应的催化性能,考察反应温度、原料配比和空速等工艺条件对反应的影响。采用NH₃-TPD、吡啶IR吸附和N2吸附-脱附等手段对USY分子筛酸性质和孔结构进行表征。结果表明,USY分子筛在烷基转移反应中具有较好的催化性能,二仲丁苯转化率为87.7%,三仲丁苯转化率为19.3%,仲丁苯选择性为91.38%,与USY分子筛的多级孔道和较多B酸位有关。多仲丁苯转化率和仲丁苯选择性随反应温度的提高而增大,原料中苯的增加可提高仲丁苯选择性,空速对二仲丁苯转化率影响较小,但对仲丁苯选择性和三仲丁苯转化率影响显著。USY分子筛上反应较适宜的工艺条件为：反应温度240 ℃,反应压力3 MPa,苯与二仲丁苯物质的量比16,二仲丁苯空速1.4 h^-1。     

Eu2+-activated blue-emitting glass phosphor derived from Eu3+ exchanged USY zeolites by thermal treatment in reducing atmosphere

In this work, we report a facile method to prepare Eu²⁺ activated blue-emitting glass phosphor via loading Eu³⁺ into USY (Na₂₈Si₁₆₈Al₂₈O₃₈₄·240H₂O, Si/Al ratio=6) zeolites’ cavities followed by thermal treatment in reducing atmosphere. The zeolites powders containing Eu³⁺ were treated at different temperatures from 800?°C to 1200?°C in flowing 5%H₂ +?95%N₂ ambient. The photoluminescence properties were investigated on aspects of the emission and excitation spectra, internal quantum efficiency (IQE), thermal stability and the fluorescence lifetime. The XRD patterns showed that the sample calcined at 950?°C was of pure glassy state. Under the broad 200–430?nm excitation, a strong blue emission band peaked at 451?nm with a full width of half maximum (FWHM) value of 74?nm was observed for this sample. Under the 365?nm excitation, the samples treated at different temperatures showed monotone red shift in the emission peak wavelengths with the thermal treatment temperature increasing. Transparent glass sheets were obtained from the glass phosphor powders by spark plasma sintering (SPS) at 1200?°C, 1250?°C and 1300?°C. The optical transmittance and thermal conductivity of transparent glass sheets were measured. The results indicated that this glass phosphor may be a potential candidate material for white LEDs.     

Kinetic modeling of catalytic conversion of methylcyclohexane over USY zeolites: Adsorption and reaction phenomena

Catalytic conversion of cycloparaffins is a complex process involving competing reaction steps. To understand this process, FCC experiments using methylcyclohexane (MCH) on USY zeolite catalysts were carried out in the mini‐fluidized CREC riser simulator. Runs were developed under relevant FCC process conditions in terms of partial pressures of MCH, temperatures (450–550°C), contact times (3–7 s), catalyst‐oil mass ratios (5), and using fluidized catalysts. MCH overall conversions ranged between 4 to 16 wt %, with slightly higher conversions obtained using the larger zeolite crystallites. Moreover, it was found that MCH undergoes ring opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. A heterogeneous kinetic model for MCH conversion including thermal effects, adsorption and intrinsic catalytic reaction phenomena was established. Adsorption and kinetic parameters were determined, including the heat of adsorption (?40 kJ/mol), as well as thermal and primary catalytic intrinsic activation energies, which were in the range of 43–69 kJ/mol, and 50–74 kJ/mol, respectively. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

介-微孔ZSM-5分子筛的原位合成

在ZSM-5合成过程中引入高分子量三嵌段共聚物P123,原位合成介-微孔ZSM-5分子筛,采用XRD、IR、BET和TEM对材料进行表征。结果表明,合成材料的主体结构为ZSM-5分子筛,比表面积为372 m²·g^-1,孔体积为0.226 mL·g^-1,其中,介孔比表面积为44 m²·g^-1,介孔孔体积为0.068 mL·g^-1,为介-微孔分子筛的合成开发了一条全新的技术路线。     

Investigation of pyridine sorption in USY and Ce/USY zeolites by liquid phase microcalorimetry and thermogravimetry studies

USY (ultrastabilized Y) and Ce/USY (5 wt.% supported) zeolite acidities were characterized by microcalorimetric and adsorption studies of pyridine using liquid phase (Cal-Ad), thermogravimetry, and infrared analysis. The average adsorption enthalpies determined by microcalorimetry were −125.0 kJ mol⁻¹ for USY and −97.2 kJ mol⁻¹ for Ce/USY. A heterogeneous distribution of acid sites with heats of adsorption ranging from −134.0 (maximum heat value for USY) to −73.5 (minimum heat value for Ce/USY) kJ mol⁻¹ was found for both zeolites. A two-site model was best fitted by the Cal-Ad method for HUSY (n₁ = 0.1385 mmol g⁻¹ with ΔH₁ = −134.0 kJ mol⁻¹, and n₂ = 0.7365 mmol g⁻¹ with ΔH₂ = −101.5 kJ mol⁻¹) and Ce/HUSY (n₁ = 0.0615 mmol g⁻¹ with ΔH₁ = −117.6 kJ mol⁻¹, and n₂ = 0.7908 mmol g⁻¹ with ΔH₂ = −83.6 kJ mol⁻¹). DRIFTS measurements after pyridine adsorption showed that USY zeolite possesses only Brønsted acidity and that cerium impregnation leads to the appearance of Lewis sites. Based on these results, three families of acid strength were distinguished: (i) strong Brønsted sites (ΔH > −130 kJ mol⁻¹); (ii) Brønsted sites with intermediate strength (−100 < ΔH < −130); and (iii) weak Brønsted and Lewis sites (ΔH < −100). Thermogravimetric analysis showed that the strongest sites were able to retain pyridine up to 800 °C and that cerium incorporation leads to a more stable zeolite. A loss of strength was observed after impregnation. The total number of sites desorbed after gas adsorption (0.88 and 0.95 mmol for HUSY and Ce/HUSY, respectively) supports the Cal-Ad results (0.88 and 1.19 mmol for HUSY and Ce/HUSY, respectively) and indicates that not all Al sites are available to pyridine. The methodology used in this work for solid acid characterization (Cal-Ad) proved to be efficient in the evaluation of acid strength, total number and distribution of acid sites. XRPD, ICP-AES, ²⁷Al NMR, and FTIR were used for additional structural characterization.     

Y型分子筛介孔改性的研究进展

Y型分子筛在催化裂化领域有着极其重要的应用,对其的介孔改性研究也引起了国内外研究者的广泛关注。本文综述了近年来Y型分子筛介孔改性的方法,指出了各种方法的优缺点,重点评述了高温水蒸气脱铝过程以及使用孔导向剂脱硅过程中介孔的形成机理,分析了通过脱铝和脱硅向Y型分子筛引入介孔时对其酸性和水热稳定性产生的影响。对介孔改性后的Y型分子筛的应用进行了总结,认为介孔改性的Y型分子筛将广泛应用于煤、生物质及其他含碳原料催化转化等领域。