改性Hβ沸石的物化性能表征

用相同物质的量浓度的硝酸铵、柠檬酸以及柠檬酸铵溶液对Naβ沸石进行改性处理得到Hβ沸石;采用XRD、XRF、FT-IR、27Al MAS NMR和29Si MAS NMR等表征手段进行分析.结果表明,采用含羟基的柠檬酸或柠檬酸铵对Naβ沸石进行改性处理,不但可以提高样品结晶度还可以有效限制骨架铝的脱除;经柠檬酸或柠檬酸铵改性可以使Naβ中的Al(S4R,SiteA)转化成Al(S6R,SiteB),而硝酸铵改性的Naβ沸石中只发现一种骨架四面体;还发现硝酸铵和柠檬酸铵改性Naβ沸石后,少量的骨架铝转化为非骨架铝并存在于孔道内,而经过柠檬酸改性后,这部分非骨架铝被带出孔道.     

改性Hβ沸石的物化性能表征

用相同摩尔浓度的硝酸铵,柠檬酸以及柠檬酸铵溶液对Naβ沸石进行改性处理得到Hβ沸石;采用XRD、XRF 、FT-IR、27Al MAS NMR和29Si MAS NMR等表征手段进行分析.结果表明,采用含羟基的柠檬酸或柠檬酸铵对Naβ沸石进行改性处理,不但可以提高样品结晶度还可以有效限制骨架铝的脱除;经柠檬酸或柠檬酸铵改性可以使Naβ中的Al(S4R,SiteA)转化成Al(S6R,SiteB),而硝酸铵改性的Naβ沸石中只发现一种骨架四面体;还发现硝酸铵和柠檬酸铵改性Naβ沸石后,少量的骨架铝转化为非骨架铝并存在于孔道内,而经过柠檬酸改性后,这部分非骨架铝被带出孔道.     

金属改性对多环芳烃选择性开环Pt/Beta催化剂性能的影响

以离子交换法对Beta分子筛进行Mg、Ce、Ga金属改性,并制得不同金属改性的Pt/Beta催化剂。本文采用XRD、XRF、NH₃-TPD、Py-IR、H₂-O₂、TEM、H₂-TPR、H₂-TPD及XPS等手段表征了改性前后样品的物化性质,并考察了改性前后样品的多环芳烃选择性开环性能。结果表明,改性金属对B酸中心的取代效应和对L酸中心的补偿效应,可显著调控分子筛酸性位的类型与强度。改性金属可增强金属-载体强相互作用（SMSI）,一方面促进贵金属铂的分散,提高铂纳米颗粒的热稳定性;另一方面产生铂纳米颗粒向载体的电子偏移或离域,影响H₂在铂纳米颗粒上的活化与脱附。此外,金属Ga可以选择性毒化铂纳米颗粒的活性位。改性金属显著影响Pt/Beta催化剂转化甲基萘的活性、稳定性及轻芳烃选择性,金属Ga、Ce改性可显著提高催化剂的稳定性,Ga改性催化剂的轻芳烃选择性最优。     

介孔构建对CuY甲醇氧化羰基化反应活性的影响

采用H₄EDTA、H₂Na₂EDTA和NaOH溶液对原始NaY分子筛分别进行单独酸碱改性和酸碱连续改性,并采用液相离子交换法制备相应的CuY催化剂。结合N₂物理吸附、TEM、XRD、²⁹Si NMR、²⁷Al NMR、NH₃-TPD、Py-IR、ICP、XPS和CO-FTIR等对载体和催化剂的结构进行表征,研究了NaY分子筛介孔构建对CuY催化甲醇氧化羰基化反应活性的影响。结果表明,NaY分子筛经H₄EDTA单独处理后,部分骨架铝被脱除形成非骨架硅铝物种,得到的E-NaY并未形成明显的介孔;E-NaY经H₂Na₂EDTA酸洗处理后,非骨架铝和部分骨架铝被脱除,得到的EW-NaY具有明显的介孔结构;而E-NaY和EW-NaY经0.2 mol/L NaOH碱处理后,分子筛发生脱硅,同时伴随着非骨架铝重新插回分子筛骨架,得到的E0.2AT-NaY和EW0.2AT-NaY具有丰富的介孔结构。其中,EW0.2AT-NaY的介孔孔容（0.45 cm³/g）最大,且有丰富的Al缺陷结构,能够与反应物接触的Cu⁺交换位利用率最高。然而,由于EW0.2AT-NaY脱铝程度明显高于E0.2AT-NaY,导致能够与反应物接触的Cu⁺交换位数量（66 μmol/g）明显小于E0.2AT-NaY（176 μmol/g）,最终导致EW0.2AT-CuY催化剂中Cu⁺活性位数量及催化活性略低于E0.2AT-CuY,二者的催化活性约为原始CuY催化剂的2.2倍。     

柠檬酸改性H-beta催化甲苯和叔丁醇烷基化

采用不同浓度的柠檬酸（HCA）对H-beta分子筛样品进行改性，通过XRD、SEM、TEM、FTIR、N₂物理吸脱附、NH₃-TPD及吡啶Py-IR等手段对改性分子筛进行了表征。实验结果表明，适宜浓度的柠檬酸改性不但没有破坏H-beta分子筛的骨架结构，而且在脱铝的同时兼具补铝功能。改性后的H-beta分子筛孔道更加畅通，虽然总酸量有所下降，但对烷基化有利的中强酸量和B酸含量却明显增加，催化活性增强。但柠檬酸浓度过高会脱除骨架铝，破坏晶格结构，导致催化活性降低。催化剂的甲苯叔丁基化活性评价表明，适宜的柠檬酸处理浓度为0.25mol/L。在0.25HCA/H-beta催化剂作用下，甲苯转化率为67.0%，对叔丁基甲苯的选择性高达80.4%。     

十氢萘在HY和Beta分子筛上加氢开环的研究

采用高温高压反应釜研究了十氢萘在低硅铝比HY分子筛[n(Si)/n(Al)=3.2]、Beta分子筛n(Si)/n(Al)=9.7]和双功能催化剂Pt-HY、Pt-Beta上的加氢开环反应,考察了分子筛孔道结构及酸性质、贵金属Pt及反应温度等因素对十氢萘转化率和产物选择性的影响。结果表明,十氢萘在Beta分子筛上的转化率较高,且有大量脱氢缩合产物（DHC）生成。Pt引入HY和Beta分子筛后,初始反应速率升高,十氢萘转化率增加,C₁₀产物中开环异构比增大,Beta分子筛上的脱氢缩合反应得到抑制。反应温度升高可以提高十氢萘在HY分子筛上的转化率,使得C₁₀产物选择性下降,而开环异构比（ROP/Iso）增大。     

USY分子筛表面酸性的调变及其在催化脱除芳烃中烯烃的应用

详细论述了柠檬酸对USY分子筛的改性作用,以脱除高溴指数芳烃中烯烃的反应为例对其催化活性进行了评价。实验结果表明:0.2mol/L柠檬酸溶液酸性适宜,对分子筛的骨架铝以及非骨架铝进行了有效的脱除,脱除的铝在分子筛中以无定形的非骨架铝形式存在。柠檬酸改性过程可使分子筛的介孔面积以及介孔孔容增大,这十分有利于减缓分子筛的失活速率。柠檬酸改性过程使分子筛表面的强B酸减少,强L酸增多,这有助于减缓分子筛上积炭的生成速率。经过柠檬酸改性的USY分子筛对脱除芳烃中微量烯烃的催化效果明显高于目前工业中在用的普通白土和改性白土。再生实验说明,经3次焙烧再生后,改性分子筛的活性依然在90%以上,具有很好的可再生性。     

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。     

三甲基膦和金属氧化物复合改性ZSM-5分子筛及其裂解性能研究

以三甲基膦（TMP）为前体对ZSM-5分子筛进行磷改性,以提升其水热稳定性,然后再分别通过等体积浸渍法引入Ga₂O₃或ZnO,制备得到磷和金属氧化物复合改性的ZSM-5分子筛。利用X射线衍射（XRD）、固体核磁（MAS NMR）、氨程序升温脱附（NH₃-TPD）以及吡啶吸附傅里叶变换红外光谱（Py-FTIR）等表征手段系统地研究了磷和金属氧化物复合改性对ZSM-5分子筛的物化性质、P和Al相互作用以及酸性的影响。并以正十四烷裂解为探针反应,研究磷和金属氧化物复合改性对ZSM-5分子筛催化裂解性能的影响。研究结果表明以三甲基膦为前体对ZSM-5分子筛改性,再引入金属氧化物的复合改性方式制备的催化裂解催化剂不仅具有较高的酸性保留度,具有较高的催化裂解活性,也同时保留了金属氧化物中心的脱氢作用,从而提升了C₂⁼~C₄⁼收率及选择性,同时降低了积炭的生成。     

脱水处理对HZSM-5分子筛甲苯择形歧化性能的影响

通过²⁷Al MAS NMR、NH₃-TPD和FT-IR等表征手段研究了脱水处理对HZSM-5分子筛催化剂的结构和催化性能的影响。HZSM-5分子筛经过371 ℃水蒸汽处理后，分子筛的部分骨架铝脱出,形成非骨架铝物种，该非骨架铝物种对甲苯择形歧化反应具有较大影响。HZSM-5分子筛的酸性变化主要是由于非骨架铝物种SiAl（OH）的变化而引起，随着脱水温度的升高，HZSM-5分子筛酸中心的强度下降，但酸中心数量增加，当脱水温度为400 ℃时，HZSM-5分子筛的酸中心强度和数量达到最佳，甲苯转化率为28.2%。脱水过程中，甲苯的引入可以阻止HZSM-5分子筛催化剂进一步脱水，起到稳定催化剂活性中心的作用，使催化剂的性能较为稳定。     

Realumination of dealuminated HZSM-5 zeolite by citric acid treatment and its application in preparing FCC gasoline hydro-upgrading catalyst

This article describes a novel citric acid treatment method for realuminating dealuminated HZSM-5 zeolite and its application in enhancing the performance of the zeolite derived FCC gasoline hydro-upgrading catalysts. A series of modified HZSM-5 zeolites were prepared by streaming and/or acid treatments and the influences of the different modification methods on the acidity, pore structure and catalytic performance of the modified HZSM-5 zeolite supported catalysts were compared in the present investigation. The results showed that compared with the single HCl or citric acid treatment, the steaming treatment, and the steaming/HCl treatments, the citric acid treatment after steaming exclusively increased the amount of framework Al species due to its realumination effect on the steamed HZSM-5 zeolite. This realumination effect of the citric acid treatment could optimize the ratio of framework Al to extra-framework Al in the steamed HZSM-5 zeolite and thus greatly improve the acidity distribution and pore structure of the corresponding catalyst. The catalytic performance assessments of the different zeolite supported catalysts for FCC gasoline hydro-upgrading revealed that the catalyst supported on the steaming/citric acid treated HZSM-5 zeolite had balanced initial and long-term activities in hydrodesulfurization, hydroisomerization and aromatization, high liquid yield and improved gasoline road octane number. The superior catalytic performance of the catalyst could be closely related to its suitable ratio of framework Al to extra-framework Al achieved by the combinational use of the steaming dealumination and the citric acid realumination, fully demonstrating the effectiveness of the steaming and citric acid treatments in optimizing the physicochemical properties and catalytic performance of HZSM-5 zeolite supported catalysts.     

Gallium oxide promoted zeolite catalysts for oxidehydrogenation of propane

Novel gallium-containing catalysts for oxidehydrogenation of propane, based on zeolite Beta, ZSM-5 and ferrierite, have been prepared and characterised by scanning electron microscopy, IR, MAS NMR and Raman spectroscopies. The catalytic properties of zeolitic matrixes with B, Al, and both ions at tetrahedral sites have been studied. Transformation of propane on pure zeolites and promoted with gallium (III) oxide depended on the structure of the matrix, its morphology and the type of cations occupying zeolite framework sites. Formation of new hydroxyl groups has been evidenced for some MFI zeolites promoted with Ga₂O₃.     

ZSM-5分子筛形貌及硅铝比对甲缩醛气相羰基化反应性能的影响

通过调控合成方式、改变原料比例,制备纳米棒状、纳米球状、椭球状、圆柱状及棋子状等不同形貌及硅铝比的ZSM-5分子筛,并对其催化甲缩醛气相羰基化反应性能进行详细考察。在110℃、0.6 MPa、CO与甲缩醛流速分别为100 mL·min-1和0.035 mL·min-1条件下,硅铝物质的量比为30的棋子形ZSM-5分子筛表现出最佳的催化活性,甲缩醛转化率达31.9%,目标产物甲氧基乙酸甲脂选择性为21.4%。通过XRD、SEM、XRF、Py-FTIR、NH 3-TPD以及27 Al MAS NMR等对合成的分子筛进行详细表征,发现调控分子筛形貌及硅铝物质的量比可改变ZSM-5分子筛的酸性特征,并改变分子筛骨架中活性铝物种分布。适量的中强B酸酸位及分子筛交叉孔道内较高比例的活性铝物种分布可能是硅铝物质的量比30的棋子形ZSM-5分子筛表现出较好催化活性的原因。     

Using ultrasound to improve the sequential post-synthesis modification method for making mesoporous Y zeolites

Mesoporous Y zeolites were prepared by the sequential chemical dealumination (using chelating agents such as ethylenediaminetetraacetic acid, H₄EDTA, and citric acid aqueous solutions) and alkaline desilication (using sodium hydroxide, NaOH, aqueous solutions) treatments. Specifically, the ultrasound-assisted alkaline treatment (i.e., ultrasonic treatment) was proposed as the alternative to conventional alkaline treatments which are performed under hydrothermal conditions. In comparison with the hydrothermal alkaline treatment, the ultrasonic treatment showed the comparatively enhanced efficiency (with the reduced treatment time, i.e., 5 min vs. 30 min, all with 0.2 mol·L⁻¹ NaOH at 65°C) in treating the dealuminated Y zeolites for creating mesoporosity. For example, after the treatment of a dealuminated zeolite Y (using 0.1 mol·L⁻¹ H₄EDTA at 100°C for 6 h), the ultrasonic treatment produced the mesoporous zeolite Y with the specific external surface area (S_external) of 160 m²·g⁻¹ and mesopore volume (V_meso) of 0.22 cm³·g⁻¹, being slightly higher than that by the conventional method (i.e., S_external = 128 m²·g⁻¹ and V_meso = 0.19 cm³·g⁻¹). The acidic property and catalytic activity (in catalytic cracking of n-octane) of mesoporous Y zeolites obtained by the two methods were comparable. The ultrasonic desilication treatment was found to be generic, also being effective to treat the dealuminated Y zeolites by citric acid. Additionally, the first step of chemical dealumination treatment was crucial to enable the effective creation of mesopores in the parent Y zeolite (with a silicon-to-aluminium ratio, Si/Al= 2.6) regardless of the subsequent alkaline desilication treatment (i.e., ultrasonic or hydrothermal). Therefore, appropriate selection of the condition of the chemical dealumination treatment based on the property of parent zeolites, such as Si/Al ratio and crystallinity, is important for making mesoporous zeolites effectively.     

A novel method for enhancing on-stream stability of fluid catalytic cracking (FCC) gasoline hydro-upgrading catalyst: Post-treatment of HZSM-5 zeolite by combined steaming and citric acid leaching

This article describes a novel modification method consisting of steaming and subsequent citric acid leaching to finely tune acidity and pore structure of HZSM-5 zeolite and thereby to enhance the on-stream stability of the zeolite derived fluid catalytic cracking (FCC) gasoline hydro-upgrading catalyst. A series of dealuminated HZSM-5 zeolites and their derived catalysts were prepared and characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), ²⁷Al MAS NMR, nitrogen adsorption, temperature programmed desorption of ammonium (NH₃-TPD) and infrared (IR) spectroscopy of chemisorbed pyridine. The results showed that the citric acid leaching could preferentially remove the extra-framework Al (EFAl) species formed by steaming treatment and thus reopen the EFAl-blocked pore channels of the steamed zeolite. The steaming treatment at a suitable temperature and subsequent citric acid leaching not only decreased the strength of acid sites to a desirable degree but also increased the ratio of medium and strong Lewis acidity to medium and strong Brönsted acidity, both of which conferred the resulting catalyst with superior selectivity to aromatics, good hydroisomerization activity and gasoline research octane number (RON) preservability, as well as enhanced on-stream stability. The results fully demonstrated that the treatments by steaming and followed citric acid leaching can serve as an important method for adjusting the physicochemical properties of HZSM-5 zeolite.     

Si and Al MAS NMR characterization of non-hydrated zeolites Y upon adsorption of ammonia

Solid-state NMR characterization of zeolite catalysts in the hydrated state is often accompanied by an uncontrolled hydrolysis of the framework. In the present work it is demonstrated that the limitations occurring for ²⁹Si and ²⁷Al MAS NMR spectroscopy of non-hydrated zeolites Y, such as strong decrease of resolution and significant line broadening, can be overcome by loading these materials with ammonia. In the ²⁹Si MAS NMR spectra of non-hydrated and ammonia-loaded zeolites Y, no dehydration-induced high-field shift of Si(nAl) signals (n = 3, 2, 1) occurs, which is generally responsible for the loss of resolution in the spectra of non-hydrated materials. The ²⁷Al MAS NMR spectra of the non-hydrated and ammonia-loaded zeolites Y consist exclusively of signals of the tetrahedrally coordinated framework aluminum atoms with spectroscopic parameters similar to those of framework aluminum atoms in hydrated samples. The framework n_Si/n_Al ratios of the non-hydrated zeolites Y obtained by both ²⁹Si and ²⁷Al MAS NMR spectroscopy upon ammonia-loading agree well with each other.     

Effects of Modified Beta Zeolites with Acid on Anisole Acetylation in a Fixed Bed Reactor

A beta zeolite sample (Si/Al = 30) was modified by citric acid, tartaric acid, and hydrochloric acid. The catalytic performances of these zeolite together with another beta zeolite (Si/Al = 12.5) were tested in the anisole acetylation in a fixed-bed configuration. The zeolites were characterized by powder X-ray diffraction, FT-IR of adsorbed pyridine, and temperature programmed desorption of ammonia. The ratios of Si/Al, the specific surface areas, and the pore sizes were also measured. The results showed that the most active and stable behavior was achieved on the HCl treated zeolite. The strong acid sites as many as possible but with an appropriate concentration and strength were needed in order to obtain an optimum activity and stability.     

有机酸改性对USY分子筛晶体结构的影响

采用有机酸作为脱铝改性剂,对工业水热超稳Y型分子筛USY进行了化学改性.考察了酸的加入量、反应温度和反应时间对分子筛晶体结构的影响.结果表明,该有机酸可以起到脱除USY非骨架铝的作用,改性后分子筛的结晶度明显提升.     

Transalkylation of Multi-secbutylbenzenes with Benzene over Hierarchical Beta Zeolite

A hierarchical beta zeolite synthesized by quasi-solid phase conversion method was characterized by BET, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (X...