Spherical MCM-41 as support material in enantioselective HPLC

Thoelen, Carla; Paul, Johan; Vankelecom, Ivo F.J.; Jacobs, Pierre

doi:10.1016/s0957-4166(00)00439-0

Cited by 43 publications

(26 citation statements)

References 10 publications

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“…Chromatography is among the applications of MTS, which has received considerable attention. Mesostructured silicas have been proposed as stationary phases for capillary GC [8], size exclusion chromatography (SEC) [9][10][11], normal-phase HPLC [12,13], chiral HPLC [14,15], RP-HPLC [16,17], and protein separation by RP-HPLC [18]. Their high specific surface area, high pore volume, and adjustable pore size, in the range of 2-10 nm were expected to improve the retention capacity, the column permeability, and the molecular selectivity, respectively, during the separation processes.…”

Section: Introductionmentioning

confidence: 99%

Spherical ordered mesoporous silicas and silica monoliths as stationary phases for liquid chromatography

Galarneau¹,

Iapichella

Brunel

et al. 2006

J of Separation Science

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Ordered mesoporous silicas such as micelle-templated silicas (MTS) feature unique textural properties in addition to their high surface area (approximately 1000 m2/g): narrow mesopore size distributions and controlled pore connectivity. These characteristics are highly relevant to chromatographic applications for resistance to mass transfer, which has never been studied in chromatography because of the absence of model materials such as MTS. Their synthesis is based on unique self-assembly processes between surfactants and silica. In order to take advantage of the perfectly adjustable texture of MTS in chromatographic applications, their particle morphology has to be tailored at the micrometer scale. We developed a synthesis strategy to control the particle morphology of MTS using the concept of pseudomorphic transformation. Pseudomorphism was recognized in the mineral world to gain a mineral that presents a morphology not related to its crystallographic symmetry group. Pseudomorphic transformations have been applied to amorphous spherical silica particles usually used in chromatography as stationary phases to produce MTS with the same morphology, using alkaline solution to dissolve progressively and locally silica and reprecipitate it around surfactant micelles into ordered MTS structures. Spherical beads of MTS with hexagonal and cubic symmetries have been synthesized and successfully used in HPLC in fast separation processes. MTS with a highly connected structure (cubic symmetry), uniform pores with a diameter larger than 6 nm in the form of particles of 5 microm could compete with monolithic silica columns. Monolithic columns are receiving strong interest and represent a milestone in the area of fast separation. Their synthesis is a sol-gel process based on phase separation between silica and water, which is assisted by the presence of polymers. The control of the synthesis of monolithic silica has been systematically explored. Because of unresolved yet cladding problems to evaluate the resulting macromonoliths in HPLC, micromonoliths were synthesized into fused-silica capillaries and evaluated by nano-LC and CEC. Only CEC allows to gain high column efficiencies in fast separation processes. Capillary silica monolithic columns represent attractive alternatives for miniaturization processes (lab-on-a chip) using CEC.

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Section: Introductionmentioning

confidence: 99%

Spherical ordered mesoporous silicas and silica monoliths as stationary phases for liquid chromatography

Galarneau¹,

Iapichella

Brunel

et al. 2006

J of Separation Science

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“…[1,2] Among them, silicalites, zeolites having the MFI framework topology, have been studied extensively with regards to the selective separation of hydrocarbons [3] and the development of electrode materials, [4] membranes, [5] and catalysts. [6] Because many emerging applications of porous materials require precise control of crystal size, shape, and orientation, [7,8] the development of new synthesis strategies is increasingly important. For example, the properties of spherical mesoporous silica particles with a narrow particle size distribution as a material for column chromatography are superior to those of curved hexagonal rods with the same structure.…”

mentioning

confidence: 99%

“…For example, the properties of spherical mesoporous silica particles with a narrow particle size distribution as a material for column chromatography are superior to those of curved hexagonal rods with the same structure. [7] Recently, it has been reported that the microwave synthesis method could provide an efficient way to control particle size distribution, [9] phase selectivity, [10] and macroscopic morphology [11] in the synthesis of porous materials as well as result in fast crystallization. [12] However, to our knowledge, there are few reports of microwave techniques being utilized to control the morphology of porous materials.…”

mentioning

confidence: 99%

Microwave Fabrication of MFI Zeolite Crystals with a Fibrous Morphology and Their Applications

Hwang¹,

Chang²,

Park³

et al. 2005

Angew Chem Int Ed

176

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“…MCM-41 silicas have been proposed as possible stationary phases for size-exclusion chromatography, [9] normal-phase HPLC, [10] capillary gas chromatography, [11] and enantioselective HPLC. [12,13] The control of the size and shape of the adsorbent particles is an essential condition for any chromatographic application: particle-size scattering affects separation and plate height. Indeed, the preparation of spheres of MTS with predetermined monodispersed size has been the target of several research groups.…”

mentioning

confidence: 99%

Morphological Control of MCM-41 by Pseudomorphic Synthesis

Martin

Galarneau

Renzo

et al. 2002

Angew. Chem. Int. Ed.

186

167

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The development of micelle-templated silicas (MTS) has represented one of the most original fields of materials research since the seminal papers from the Kresge and Beck groups on MCM-41 and MCM-48. [1,2] The self-assembly of surfactant aggregates and mineral species can be controlled to provide stable mesoporous materials with extremely narrow pore-size distributions. Several recent reviews show the advances in the preparation of ordered porous oxides, [3±5] as well as their applications in catalysis. [6±8] Adsorbents with narrow pore-size distribution at the nanometer scale allow new applications to be devised for the separation of large organic molecules. MCM-41 silicas have been proposed as possible stationary phases for size-exclusion chromatography, [9] normal-phase HPLC, [10] capillary gas chromatography, [11] and enantioselective HPLC. [12,13] The control of the size and shape of the adsorbent particles is an essential condition for any chromatographic application: particle-size scattering affects separation and plate height. Indeed, the preparation of spheres of MTS with predetermined monodispersed size has been the target of several research groups. Positive results have been obtained by introducing surfactant templates in classical preparations of silica gel with controlled grain size. In this way, spheres of MTS have been prepared from water ± alcohol systems, [14,15] by controlled hydrolysis, [16,17] or by spray-drying techniques. [18] A frequent drawback of these methods is the need to simultaneously optimize the conditions for the synthesis of the desired silica ± surfactant mesophase and for the successful formation of monodispersed spheres. This situation restrains the experimental conditions and makes a fine tuning of the properties of MTS, such as, pore size and topology, wall thickness, and aluminum content, difficult. It would be expedient to independently optimize the properties of the particles and the properties of the micelle-templated phase. Herein, a method to achieve this result by transformation of preformed spheres of silica gel into MTS is proposed.The synthesis procedure is directly adapted from the synthesis of MCM-41, [1,2] by using commercial spheres of silica gel as the source of silica. Lichrosphere 100 (Merck) was stirred in an alkaline solution of cetyltrimethylammonium bromide (CTAB), the molar composition of the system being 1 SiO 2 /0.25 NaOH/0.1 CTAB/20 H 2 O. After 30 min stirring at room temperature, the system was put in an autoclave at 388 K for 24 h. The parent silica (Lichrosphere 100) and the recovered solid share the same spherical morphology and granulometric distribution (Figure 1). However, while the parent silica is amorphous, the CTAB-treated solid presents the characteristic X-ray powder diffraction pattern of MCM-41. Figure 1. Pseudomorphic transformation of silica gel to MCM-41. Micrographs (a, b), granulometric distributions; the distribution is given in volume V as a function of particle diameter D p (c, d), and powder diffraction patterns (e, f) fo...

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Spherical MCM-41 as support material in enantioselective HPLC

Cited by 43 publications

References 10 publications

Spherical ordered mesoporous silicas and silica monoliths as stationary phases for liquid chromatography

Spherical ordered mesoporous silicas and silica monoliths as stationary phases for liquid chromatography

Microwave Fabrication of MFI Zeolite Crystals with a Fibrous Morphology and Their Applications

Morphological Control of MCM-41 by Pseudomorphic Synthesis

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