中孔复合锆-铝氧化物微球的制备及其正相色谱性能研究

复合氧化物通常表现出与单一氧化物不同的物理化学性质（如晶体结构、孔结构和表面性质等方面）,已广泛用作催化剂、吸附剂和离子交换剂。1993年,Kaneko等采用共沉淀法制备的SiO2-TiO2,SiO2-Al2O3等复合氧化物的环境保护、痕量富集、氨基酸分离等方面取得较好的应用效果。但复合氧化物作为液相色谱固定相的研究很少报道。近年来,我们从制备、表征到正相、反相色谱性能等方面对MgO-ZrO2和SiO2-ZrO2复合氧化物作为色谱填料进行了系统的研究,发现MgO和SiO2掺杂可以有效地改善ZrO2的孔结构,提高柱效。本文用溶胶－凝胶方法制备了质量投料比m（硝酸铝）：m（氧氯化锆）＝20：64的ZrO2-Al2O3复合氧化物微球,考察酸腐蚀前后其晶形、表面酸碱性和孔容、孔径的变化,以及它们的正相色谱性能。     

锆-铝复合氧化物固定相的制备、表征及其色谱性能考察

利用溶胶-凝胶技术制备了无机杂化材料锆铝复合氧化物,对其物理化学性能进行了研究。平均孔径5-8nm,并且孔径分布较窄;表面呈现酸碱两性;氧化铝的掺杂可以提高填料的经表面积。同时以酸性、碱性和中性化合物为溶质,对锆铝填料的正相色谱性能和烷基膦酸改性的锆铝填料的反相色谱性能进行了系统评价,研究结果表明,锆铝填料适合于碱性化合物分离,并且其分离选择性在一定程度上随流动相性质而变;烷基膦酸改性的锆铝填料则呈现出反相色谱特征。     

SAM/AES analysis of grain boundaries in zirconia ceramics

Grain boundary impurity silicate phases and the segregation process of cations to grain boundaries in zirconia ceramics have been investigated using SAM/AES. Point analyses at triple points and grain surfaces revealed a glassy silicate phase between the grain. The analysis of KLL and LMM Auger transitions for alumina and silica indicate that the grain boundary phase consists of about two monolayers of silica covering the alumina enriched silicate phase. In titania-stabilised zirconia ceramic, titanium cations are found to be enriched by a factor of 3.8 in the near-grain-boundary region.     

Evaluation of titania as an ion-exchanger and as a ligand-exchanger in HPLC

Summary The chromatographic properties of titania have been compared with those of zirconia and alumina, by comparison of their relative Lewis acidities whenp-substituted benzoic acids were chromatographed with aqueous mobile phases. The retention behavior ofp-substituted benzoic acids on titania was found to be similar to that on zirconia; the slopes of plots of retention factors against solute pK _a were approximately parallel for all pH values and the slopes obtained were similar to the average slope for zirconia. The shapes of solute peaks on titania were more symmetrical than on alumina and zirconia. The effect of calcination temperature on the chromatographic properties of titania was examined by use of titania prepared at different temperatures. The results obtained clearly showed that the preparation temperature affected the chromatographic properties of titania. It seemed, for example, that titania dried at 40°C behaved as a cation-exchanger, titania heated at 200°C behaved as an amphoteric exchanger, and titania calcined at 600°C behaved as an anion-exchanger in the pH range 4.1–6.5 It was found that the control of the preparation temperature enabled us to make effective use of titania.     

The retention behaviour of polar compounds on zirconia based stationary phases under hydrophilic interaction liquid chromatography conditions

The most separations in HILIC mode are performed on silica-based supports. Nevertheless, recently published results have indicated that the metal oxides stationary phases also possess the ability to interact with hydrophilic compounds under HILIC conditions. This paper primarily describes the retention behaviour of model hydrophilic analytes (4-aminobenzene sulfonic acid, 4-aminobenzoic acid, 4-hydroxybenzoic acid, 3,4-diaminobenzoic acid, 3-aminophenol and 3-nitrophenol) on the polybutadine modified zirconia in HILIC. The results were simultaneously compared with a bare zirconia and a silica-based HILIC phase. The mobile phase strength, pH and the column temperature were systematically modified to assess their impact on the retention of model compounds. It was found that the retention of our model hydrophilic analytes on both zirconia phases was mainly governed by adsorption while on the silica-based HILIC phase partitioning was primarily involved. The ability of ligand-exchange interactions of zirconia surface with a carboxylic moiety influenced substantially the response of carboxylic acids on the elevated temperature as well as to the change of the mobile phase pH in contrast to the silica phase. However, no or negligible ligand-exchange interactions were observed for sulfanilic acid. The results of this study clearly demonstrated the ability of modified zirconia phase to retain polar acidic compounds under HILIC conditions, which might substantially enlarge the application area of the zirconia-based stationary phases.     

Preparation and characterization of phosphatidylcholine‐coated zirconia–magnesia stationary phase for artificial membrane chromatography

Immobilized artificial membrane chromatography stationary phase was prepared by coating soybean phosphatidylcholine (PC) on zirconia–magnesia micro‐particles. The stability and chromatographic properties were investigated and compared with the PC‐coated silica chromatography stationary phase prepared by the same method. PC‐coated zirconia–magnesia chromatography stationary phase was more stable than the silica especially on resisting organic solvents. Hydrophobic action was the main factor for the retention of analyte on the new artificial membrane chromatography stationary phase, and electrostatic interaction had some contribution to retention. In addition, the special interaction between analyte and matrix affected retention greatly. Basic solutes were appropriate to be analyzed on PC‐coated zirconia–magnesia stationary phase and acidic solutes were appropriate to be done on the silica one. Hence, the two different matrices artificial membrane stationary phases were perfectly complementary.     

Native and modified alumina,titania and zirconia in normal and reversed-phase high-performance liquid chromatography

Summary Chromatographic properties of silica, alumina, titania and zirconia have been investigated in normal phase mode in the separation of test mixtures of basic, neutral and acidic compounds. In contrast to silica the chromatographic behaviour revealed the basic properties of the alumina, titania and zirconia surfaces. Therefore, separation of basic compounds on these packings seems very promising. Lypophilic packings have been synthesized by modification of titania, zirconia and alumina with organosilanes and polymers and tested for the separation of basic compounds and proteins. High hydrolytic stability of the modified packings was observed during separations with strong alkali and acidic eluents.     

Retention and selectivity tests of silica-based and metal-oxide bonded stationary phases for RP-HPLC

Chromatographic properties of silica-, zirconia- and alumina-based columns with octadecyl-, polyethylene glycol- and pentafluorophenylpropyl-bonded stationary phases were tested. Selectivities of nine columns for LC were characterized using chromatographic methods including Walters, Engelhardt, Tanaka and Galushko hydrophobicity and silanol activity tests, measurements of methylene selectivity in various aqueous-methanol and aqueous-acetonitrile mobile phases and of gradient lipophilic capacity as a measure of the effect of the sample hydrophobicity on gradient-elution separations. A semi-empirical interaction indices model, assuming a predominant role of the solvophobic interactions of test compounds with different polarities, was compared with the linear free energy relationships approach taking into account selective polar interactions. The interaction indices model was applied to both non-polar stationary phases bonded on silica, alumina and zirconia supports, and to the non-modified adsorbents in the normal-phase LC. The retention data of isomeric naphthalene disulfonic acids were used to compare the attractive and repulsive ionic interactions of the columns in purely aqueous mobile phases. The results of the hydrophobicity and polarity tests were consistent, and allowed column characterization and classification. Silanol activity was important with octadecyl silica columns, but was relatively insignificant with bonded polyethylene glycol and pentafluorophenylpropyl phases on silica gel support. Polar interactions with the alumina and zirconia support materials significantly affect the retention.     

New polymer coated anion-exchange HPLC-phases: Immobilization of poly (2-hydroxy, 3N-ethylenediamino) butadiene on silica and alumina

Summary PHEB=POLY(2-hydroxy, 3N-ethylenediamino)butadiene has been synthesized. This unsaturated pre-polymer can be immobilized on different, preferably inorganic supports of suitable porosity such as silica or alumina by cross-linking. Weak anion-exchange phase are obtained. Such phases do not have the disadvantages of organic polymeric phases, regarding pressure stability and swelling by solvent influence. The ion-exchange capacity and the retentivity of IE-separations can deliberately be varied via the thickness of the cross-linked polymer layer. Alumina can also be coated with PHEB applying the same cross-linking procedure. Such phases exhibit an exceptional chemical stability even when operated with mobile phases at very high pH-values. Separations of excellent selectivity are achieved for inorganic anions, as well as with mixtures of aliphatic and aromatic free acids also including hydroxy- (mono- or poly)carboxylic acids.     

Structure,thermal stability,and catalytic performance of MgO-ZrO<Subscript>2</Subscript> composites

A composite constituted by zirconia supported on magnesia is thermally treated. Depending on temperature, several crystal sizes and crystalline zirconia structures are obtained. At low temperatures, cubic zirconia crystals are found to be deposited on the crystalline magnesia matrix. As temperature increases, the cubic zirconia phase transforms to the tetragonal and the monoclinic phases. They form clusters supported on the MgO matrix. All these results are supported by different analytical techniques and a catalytic test.     

Probing the effects of interfacial chemistry on the kinetics of phase transitions in amorphous and tetragonal zirconia nanocrystals

In this work, we examine the phase stability of both uncoated and alumina-coated zirconia nanoparticles using in-situ X-ray diffraction. By tracking structural changes in these particles, we seek to understand how changing interfacial bonding affects the kinetics of amorphous zirconia crystallization and the kinetics of grain growth in both initially amorphous and initially crystalline zirconia nanocrystals. Activation energies associated with crystallization are calculated using nonisothermal kinetic methods. The crystallization of the uncoated amorphous zirconia colloids has an activation energy of 117 +/- 13 kJ/mol, while that for the alumina-coated amorphous colloids is 185 +/- 28 kJ/mol. This increase in activation energy is attributed to inhibition of atomic rearrangement imparted by the alumina coating. The kinetics of grain growth are also studied with nonisothermal kinetic methods. The alumina coating again dramatically affects the activation energies. For colloids that were coated with alumina when they were in an amorphous structure, the coating imparts a 5x increase in the activation energy for grain growth (33 +/- 8 versus 150 +/- 30 kJ/mol). This increase shows that the alumina coating inhibits zirconia cores from coarsening. When the colloids are synthesized in the tetragonal phase and then coated with alumina, the effect of surface coating on coarsening kinetics is even more dramatic. In this case, a 10x increase in activation energies, from 28 +/- 3 kJ/mol for the uncoated particles to 300 +/- 25 kJ/mol for the alumina-coated crystallites, is found. The results show that one can alter phase stability in colloidal systems by using surface coatings and interfacial energy to dramatically change the kinetic barriers to structural rearrangement.     

Columns in analytical-scale supercritical fluid chromatography: From traditional to unconventional chemistries

Within this review, we thoroughly explored supercritical fluid chromatography (SFC) columns used across > 3000 papers published from the first study carried out under SFC conditions in 1962 to the end of 2022. We focused on the open tubular capillary, packed capillary, and packed columns, their chemistries, dimensions, and trends in used stationary phases with correlation to their specific interactions, advantages, drawbacks, used instrumentation, and application field. Since the 1990s, packed columns with liquid chromatography and SFC-dedicated stationary phases for chiral and achiral separation are predominantly used. These stationary phases are based on silica support modified with a wide range of chemical moieties. Moreover, numerous unconventional stationary phases were evaluated, including porous graphitic carbon, titania, zirconia, alumina, liquid crystals, and ionic liquids. The applications of unconventional stationary phases are described in detail as they bring essential findings required for further development of the supercritical fluid chromatography technique.     

磷霉素改性氧化锆固定相色谱性能研究

本文利用磷霉素与氧化锆表面的强Ｌｅｗｉｓ酸碱作用,分别采用静态和动态两种途径以磷霉素对自制ＺｒＯ２固定相进行改性,考察了改性前后固定相色谱性能的变化。通过磷霉素改性,能够较好地覆盖氧化锆表面存在的Ｌｗｅｉｓ酸活性中心点,从而减少对酸性化合物的不可逆吸附及拖尾现象。磷霉素动态改性氧化锆表现出一定的反相色谱性能,静态改性氧化锆则表现出较强的极性。     

Preparation of amino-zirconia bonded phases and their evaluation in hydrophilic interaction chromatography of carbohydrates with pulsed amperometric detection

A series of non-porous, microspherical zirconia-based stationary phases with surface bound amine functionality have been introduced and evaluated in hydrophilic interaction chromatography (HILIC) of underivatized, neutral carbohydrates and anion exchange chromatography of nucleotides using pulsed amperometric detection and ultraviolet detection, respectively. Three aminopropyl alkoxysilane compounds were used in the surface modification of the non-porous zirconia support, namely 3-aminopropyltrimethoxysilane (monoamine), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (diamine), and trimethoxysilylpropyldiethylenetriamine (triamine). Due to the relatively low specific surface area of the non-porous zirconia support used in this study (ca. 7.3 m²/g), zirconia with surface coating of the triamine type yielded the best results as far as the separations of chitooligosaccharides and maltooligosaccharides are concerned. Since a non-porous zirconia could be readily modified with amine functionality via Zr? O? Si bonds, it is expected that all the three aminopropyl alkoxysilane compounds would yield satisfactory results with porous zirconia microparticles because of their much higher specific surface areas. Although the non-porous zirconia exhibited some limitations, the present study has demonstrated that microspherical zirconia particles are suitable supports for the production of polar sorbents for HILIC of carbohydrates. Another surface modification, which involved the activation of the zirconia surface with aldehyde groups followed by reductive amination with tetraethylenepentamine, was also evaluated. Although this chemistry would in principle yield sorbents with higher concentration in amine groups, the conversion of the majority of the primary amine groups of the tetraethyle-nepetamine molecules to secondary amine functions in the course of the reductive amination reaction have provided a stationary phase that did not afford satisfactory resolution for carbohydrates. However, this same stationary phase behaved as a weak anion exchanger and allowed the high resolution separation of nucleoside-5′-mono-, -di-, and triphosphates. Overall, the results obtained with zirconia-based hydrophilic sorbents paralleled those obtained on amino-silica bonded phases.     

氧化铝和氧化锆催化剂上2-取代苯并咪唑和1,5-二取代苯并二氮的合成(英文)

In this study, alumina, zirconia, manganese oxide/alumina, and manganese oxide/zirconia have been investigated for their catalytic activity in the condensation reaction between o-phenylenediamine and an aldehyde or a ketone to synthesise 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines respectively. Surface area, surface acidity, and morphology of the catalysts have been analysed and correlated with their catalytic activity. The isolated yields of 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines are in the range of 30% to 95%. A good correlation between the amount of surface acid sites as well as the surface morphology of the catalysts and the catalytic activity has been observed. This method has been found to be simple and economical. The solid supports could be regenerated and reused without much loss in their activity. Further, the solid supports have been also found to be effective as general catalysts in the condensation of o-phenylenediamine with other substituted aldehydes and ketones.     

包覆聚合物高效液相色谱柱填料的研究进展

评述了用于高效液相色谱的包覆聚合物填料的研究进展．该类填料以无机载体为基质，包覆以多种有机聚合物层．这些新型填料既保留了有机聚合物和无机基质的优点，又克服了它们各自的缺陷．包覆的聚合物类型包括聚烃、聚醚、聚酰胺、多糖、多肽、聚硅氧烷、聚胺及多核苷酸等，无机基质包括硅胶、铝胶、钛胶、钻胶及多孔石墨化碳等．包覆聚合物固定相可用于几乎所有色谱方式，如反相高效液相色谱、高效离子交换色谱、手性固定相、超临界流体色谱、体积－排阻色谱，以及亲合色谱．     

氧化铝对Pt-SO4^2-／ZrO2-Al2O3固体酸催化剂结构与酸性的影响

通过混捏法制备了Pt-SO4^2-／ZrO2-Al2O3固体酸催化剂，考察了该催化剂在正构烷烃低温异构化反应中的催化稳定性．采用X射线衍射、差热分析、X射线光电子能谱、核磁共振、N2吸附-脱附和微量热等表征技术，对氧化铝的作用机理进行了研究．结果表明，氧化铝起到结构助催化剂作用，对四方相氧化锆具有稳定作用，并延迟了氧化锆的晶化，抑制了氧化锆的烧结，从而增大了催化剂的比表面积和孔容．XPS结果表明，Zr3d峰向低结合能方向移动，Al2p峰向高结合能方向移动，说明Al^3＋的电子向Zr^4＋偏移．微量热结果表明氧化铝的引入提高了催化剂的酸量和酸强度．^27Al固体核磁共振结果表明，Pt-SO4^2-／ZrO2-Al2O3中的六配位铝的结构发生了变化．氧化铝的引入还可能有助于氧化锆晶格缺陷的形成，焙烧过程中Al^3＋迁移进入氧化锆晶格并同晶取代Zr^4＋形成氧缺陷位，这些氧缺陷位在S=O键诱导下显示强酸性．     

Zirconia based monoliths used in hydrophilic-interaction chromatography for original selectivity of xanthines

Monolithic capillary columns based on zirconia were prepared directly from zirconium alkoxide. They were also prepared coating a classical silica based monolithic column with zirconium butoxide. Using the gradual evolution of the theophylline/caffeine separation factor, it was found that successive zirconia coatings produced the progressive fading of surface silanols replaced by Zr–OH groups. The behavior of a silica monolith coated four times with zirconium butoxide was very similar to that of a pure zirconia monolith. The dramatic change in xanthine separation factor observed with zirconia stationary phases and the theophylline and caffeine probe solutes was used to develop a complete separation of xanthines on zirconia stationary phase in less than 6 min. The three dimethylxanthine isomers, theophylline, theobromine and paraxanthine, are very difficult to separate in RPLC with classical C₁₈ stationary phases. The three isomers were easily separated in HILIC mode on a zirconia based stationary phase.     

费-托合成Co/ZrO2-Al2O3催化剂反应性能的研究

以ZrOCl2·6H2O和AlCl3为原料,采用共沉淀方法制得一系列不同ZrO2质量分数的ZrO2-Al2O3混合氧化物载体;并以该混合氧化物为载体,采用初湿浸渍法制得钴质量分数为12％的Co/ZrO2-Al2O3催化剂。XRD、NH3-TPD、TPR和原位IR等表征结果表明,随着混合载体中ZrO2质量分数的增加,载体比表面积先增加后减少,混合载体的平均孔径则小于单一氧化物ZrO2和Al2O3的平均孔径。ZrO2和Al2O3载体混合后会导致氧化物的比表面积和酸性增大并且有新的物相生成。当混合氧化物用作载体时,能够抑制载体表面金属钴的分散,改变催化剂的还原行为,降低催化剂对CO物种的吸附能力。CO加氢反应表明,与单一金属氧化物相比,钴负载ZrO2-Al2O3混合氧化物催化剂的加氢活性和重质烃选择性有所降低。     

溶质在动态改性氧化锆液相色谱柱上的保留行为

分别采用硬脂酸、环糊精和十二烷基磺酸钠动态改性自制的ZrO2微球,研究了流动相中甲醇和改性剂浓度对苯酚及苯甲酸的衍生物、苯胺衍生物及芳香烃类化合物的色谱保留行为的影响。中性及碱性化合物的保留时间较短,色谱峰对称;酸性化合物保留时间较长,色谱峰拖尾较严重。改性氧化锆表现出反相色谱性能。