Epoxidation of unsaturated fatty esters over large-pore Ti-containing molecular sieves as catalysts: important role of the hydrophobic–hydrophilic properties of the molecular sieve

Synthesis of various fine chemicals and pharmaceuticals are regulated through selective hydrogenation of α,β-unsaturated aldehydes. Hydrocinnamaldehyde is one of the important compounds in perfumery and flavouring industries. It is highly precarious and challenging to control the product selectivity as well as conversion in cinnamaldehyde hydrogenation. In this study, an effective hydrogenation of cinnamaldehyde was attained in presence of aqueous-protic organic medium by utilizing Pd/CMS and other additives of alkali such as K2CO3. The Pd/CMS catalyst along with alkali media catalyzed the hydrogenation of C=C selectively in cinnamaldehyde in order to form hydrocinnamaldehyde with 100% conversion rate. Additionally, the parallel hydrogenation of C=O and C=C bonds in cinnamaldehyde takes place in absence of media. The C=O bond reduction in cinnamaldehyde can be restricted through K2CO3 addition to aqueous-protic solution. The active sites of palladium were found to be uniform and analyzed using HRTEM data. Based on the mechanism involved in micropores of carbon molecular sieves, the key role of promoter is associated with hydrogenation of cinnamaldehyde. The catalytic criterion was appropriate with the acquired activity data.

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The Effect of Type of Acid Sites in Molecular Sieves on Activity and Selectivity in Acylation Reactions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20070728 ◽

2007 ◽

Vol 72 (5-6) ◽

pp. 728-746 ◽

Cited By ~ 15

Author(s):

Martina Bejblová ◽

Josef Vlk ◽

Dana Procházková ◽

Helena Šiklová ◽

Jiří Čejka

Keyword(s):

Molecular Sieves ◽

Molecular Sieve ◽

Acid Sites ◽

Acid Strength ◽

Zeolite Beta ◽

Mesoporous Molecular Sieves ◽

Lewis Acid Sites ◽

Mcm 41 ◽

Acylation Reactions

The role of the type of acid site (Broensted vs. Lewis) on the activity and selectivity of molecular sieve catalysts was investigated in ferrocene and toluene acylation. H-, Zn-, Fe-, Al- and La-forms of zeolite Beta, USY and mesoporous molecular sieves (Al)MCM-41, (Al)SBA-15 were tested. It was observed that addition of metal cations acting as Lewis acid sites can increase the acidity of various molecular sieve catalysts. No general relationship between the type of cation and conversion of individual substrate was found. While the highest activity in ferrocene acylation was observed after addition of Zn, in the case of toluene acylation Al-forms of catalysts were the most active. The results indicate that the acid strength of cationic Lewis sites controls their activity in acylation reactions.

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Molecular Sieve Synthesis using Metallocenes as Structure Directing Agents

MRS Proceedings ◽

10.1557/proc-368-369 ◽

1994 ◽

Vol 368 ◽

Cited By ~ 17

Author(s):

Kenneth J. Balkus ◽

Alexei G. Gabrielov ◽

Netanya Sandler

Keyword(s):

Metal Complex ◽

Metal Complexes ◽

Molecular Sieves ◽

Molecular Sieve ◽

Microporous Materials ◽

Synthesis And Characterization ◽

Bifunctional Catalysts ◽

Large Pore ◽

High Silica

ABSTRACTWe have been exploring molecular sieve synthesis using metal complexes as templates. Our objectives were to affect the crystallization of new structures as well as prepare bifunctional catalysts via the encapsulation of metal complexes during synthesis. In this paper the results for the synthesis of SiO2, AlPO4 and SAPO molecular sieves in the presence of metallocenes will be presented. In particular, Cobalticinium ion, Cp2Co+, was found to be a template for Nonasil, AlPO4−5, AlPO4−16, SAPO−16 and CoAPO−16 which are known phases but require templates. The larger decamethyl derivative, CP*2Co+ has produced a novel high silica zeolite molecular sieve, UTD-1 as well as a new SAPO phase UTD-2 which appear to be large pore materials. In all cases, the metal complex is occluded intact and cannot be extracted. Aspects of the synthesis and characterization of these microporous materials are presented below.

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VPI-5: A Novel Large Pore Molecular Sieve

MRS Proceedings ◽

10.1557/proc-111-267 ◽

1987 ◽

Vol 111 ◽

Cited By ~ 1

Author(s):

Mark E. Davis ◽

Carlos Saldarriaga ◽

Consuelo Montes ◽

Juan Garces ◽

Cyrus Crowder

Keyword(s):

Molecular Sieves ◽

Molecular Sieve ◽

Large Pore

AbstractThis paper reports a novel family of aluminophosphate based molecular sieves denoted as VPI-5. These molecular sieves are the first to contain pores larger than 10 Å. The large pores of the VPI-5 sieves consist of long channels circumscribed by eighteen membered rings and are capable of adsorbing molecules excluded from other molecular sieves.

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Preparation and Characterization of Ni-Containing Aluminophosphate Molecular Sieves

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.418-420.617 ◽

2011 ◽

Vol 418-420 ◽

pp. 617-620

Author(s):

Ying Sun ◽

Lan Ying Ge

Keyword(s):

Oxidation State ◽

Molecular Sieves ◽

Molecular Sieve ◽

Crystalline Form ◽

Spectroscopic Techniques ◽

Tetrahedral Coordination ◽

Tetrahedral Geometry ◽

Nickel Ions ◽

Aluminophosphate Molecular Sieves

Aluminophosphate molecular sieve and Ni(II)-containing APO-5 materials were synthesized hydrothermally and characterized by various analytical and spectroscopic techniques. It indicates that the nickel ions with a divalent oxidation state can incorporate into the tetrahedral coordination in mesoporous aluminophosphate very well. The better crystallizing temperature is explored. A stronger crystalline form is obtained with the addition of HF. Further, microporous aluminophosphate molecular sieves and Ni(II) ions remain in a tetrahedral geometry even after calcination at 550 °C.

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