Amino-grafted metallosilicate MCM-41 materials as basic catalysts for eco-friendly processes

Blasco-Jiménez, Davinia; Sobczak, Izabela; Ziółek, Maria; López-Peinado, A.J.; Martı́n-Aranda, R.M.

doi:10.1016/j.cattod.2010.04.031

Cited by 43 publications

(16 citation statements)

References 37 publications

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“…135 For amino groups immobilized on different supports, the conversion of benzaldehyde decreases in the order of AlMCM-41 4 NbMCM-41 4 MCM-41 in both Knoevenagel reactions. The evaluation of these materials was performed by Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate and diethyl malonate.…”

Section: View Article Onlinementioning

confidence: 93%

“…Various types of amino groups have been immobilized on mesoporous silica, leading to the formation of a series of mesoporous basic materials as listed in Table 2. 135 The nitrogen content of APMS/AlMCM-41 was measured to be 1.8 mmol g À1 , and that of 3APMS/AlMCM-41 is 4.5 mmol g À1 . To examine the influence of amine types, three organoalkoxysilanes, that is APTMS, [3-(2-aminoethylamino)propyl]trimethoxysilane (MeO) 3 Si-(CH 2 ) 3 -NH-(CH 2 ) 2 -NH 2 , and 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (MeO) 3 Si-(CH 2 ) 3 -NH-(CH 2 ) 2 -NH-(CH 2 ) 2 -NH 2 , were used as precursors and grafted onto Al-containing MCM-41, leading to the formation of materials labelled APMS/AlMCM-41, 2APMS/AlMCM-41, 3APMS/AlMCM-41, respectively (Fig.…”

Section: Mesoporous Silicamentioning

confidence: 96%

“…135 In addition, isomerization of safrole to prepare isosafrole was utilized to evaluate the basicity of materials. The activity decreased in the following order: APMS/AlMCM-41 4 2APMS/AlMCM-41 4 3APMS/AlMCM-41.…”

Section: Mesoporous Silicamentioning

confidence: 99%

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Design and fabrication of mesoporous heterogeneous basic catalysts

2015

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Mesoporous solid bases are extremely desirable in green catalytic processes, due to their advantages of accelerated mass transport, negligible corrosion, and easy separation. Great progress has been made in mesoporous solid bases in the last decade. In addition to their wide applications in the catalytic synthesis of organics and fine chemicals, mesoporous solid bases have also been used in the field of energy and environmental catalysis. Development of mesoporous solid bases is therefore of significant importance from both academic and practical points of view. In this review, we provide an overview of the recent advances in mesoporous solid bases, which is basically grouped by the support type and each category is illustrated with typical examples. Cooperative catalysts derived from the incorporation of additional functionalities (i.e. acid and metal) into mesoporous solid bases are also included. The fundamental principles of how to design and fabricate basic materials with mesostructure are highlighted. The mechanism of the formation of basic sites in different mesoporous systems is discussed as well.

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Section: View Article Onlinementioning

confidence: 93%

Section: Mesoporous Silicamentioning

confidence: 96%

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Design and fabrication of mesoporous heterogeneous basic catalysts

2015

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“…M 3+ elements will typically introduce a Brønsted acid site that is a stronger acid than the silanols, while M 4+ elements will introduce new types of hydroxyl species such as titanols [33] or even Lewis acidic sites in the case of coordinatively unsaturated Zr 4+ species [34,35] and tetrahedrally coordinated Ti sites [36]. At present, studies of the effects of heteroatom substitution on cooperative acid-base catalysts have been limited mainly to Al substitution for C-C coupling reactions and one-pot cascade reactions [13,[37][38][39][40][41][42][43][44][45][46][47][48]. In this study, we examine the effects of heteroatom substitution with materials with similar pore diameters, similar organic (amine) loadings, and approximately 5 mol% heteroatom substitution.…”

Section: Introductionmentioning

confidence: 99%

Reaction-dependent heteroatom modification of acid–base catalytic cooperativity in aminosilica materials

Moschetta

Brunelli

Jones

2015

Applied Catalysis A: General

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a b s t r a c tThe effects of heteroatom substitution on the cooperative catalytic activity of a series of bifunctional acid-base aminosilica catalysts are probed in aldol and nitroaldol condensations. Three M 3+ (B, Al, and Ga) and three M 4+ (Ti, Zr, and Ce) heteroatoms are incorporated into different samples of SBA-15 silica and then grafted with aminosilanes to produce bifunctional acid-base catalysts. The catalytic activity of each material is measured in the aldol condensation of 4-nitrobenzaldehyde with acetone at 50 • C and the nitroaldol condensation of 4-nitrobenzaldehyde with nitromethane at 40 • C and compared to the catalytic activity of a heteroatom-free aminosilica catalyst. The heteroatom substitutions produce catalysts with larger amounts of strong Lewis acid sites compared to the heteroatom-free aminosilica catalyst. We rationalize these results in the context of the physical (e.g. surface area, pore diameter, particle size) and chemical properties (e.g. total number and strength of acid sites) of each material and the proposed catalytic mechanisms of the two reactions. The increase in the number of strong Lewis acid sites of each heteroatom material decreased its activity in the aldol condensation, though four heteroatom substitutions (B, Al, Ga, and Ti) increased the catalytic activity of the aminosilica catalyst in the nitroaldol condensation. The results suggest that inclusion of a small amount of Lewis acid sites in aminosilica materials can increase the cooperative catalytic activity of the materials in the nitroaldol condensation. The results also suggest that inclusion of Lewis acid sites in aminosilica materials decreases the cooperative catalytic activity of the materials in the aldol condensation.

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“…For example, amine-functionalized mesoporous silica was successfully used as a catalyst for the Knoevenagel reaction between benzaldehyde and ethyl cyanoacetate at 375 K in the presence of DMSO as a solvent (Figure 7.13 The catalytic activity of a typical Knoevenagel condensation reaction was found to be directly proportional to the density of basic catalytic groups grafted on the support material. [77][78][79][80][81] However, significantly higher turnover numbers were obtained in the case of the primary amine-grafted mesoporous silica catalysts than the corresponding tertiary amine-grafted mesoporous silica catalysts. 77,78 The improved catalytic activity in the case of primary amine-functionalized material is the result of the transient formation of imine groups for these systems (Figure 7.14).…”

Section: Knoevenagel Condensationmentioning

confidence: 93%