Preparation of acid-base bifunctional mesoporous KIT-6 (KIT: Korea Advanced Institute of Science and Technology) and its catalytic performance in Knoevenagel reaction

Mesoporous KIT-6 supported Cr and Co-based catalysts for microwave-assisted non-oxidative ethane dehydrogenation

In the present study, mono and bi-metallic catalysts containing Cr and Co were prepared by impregnating the hydrothermally prepared mesoporous KIT-6 support with 5–10 wt% total metal content. The well-ordered three-dimensional mesoporous structure of the KIT-6 support was confirmed by small angle X-ray diffraction (XRD) patterns. N2 adsorption-desorption analysis results showed that the mesoporous structure of KIT-6 was preserved after metal loading. Structural bonds of KIT-6 support and prepared catalysts were determined by Fourier-transform infrared (FT-IR) spectroscopy. The pyridine adsorbed diffuse reflectance FT-IR (DRIFT) spectroscopy results revealed the presence of Lewis acid sites on the surface of the catalysts. Activity experiments were carried out in a microwave-heated continuous-flow fixed bed reactor system at temperature range of 350–650 °C and feed ratios of Ethane/Argon: 1/2, 1/1, 2/1 with a gas hourly space velocity (GHSV) of 18,000 ml/h.gcat. The 5Cr@KIT-6 catalyst exhibited high ethane conversion (63.5%) while the highest ethylene/hydrogen ratio (0.98) was obtained with the 2.5Cr2.5Co@KIT-6 catalyst at 450 °C. It was concluded that high temperatures (above 450 °C) facilitate the formation of side reactions and the production of aromatic compounds. The high catalytic activities of mesoporous catalysts were thought to be due to hot spots in the microwave reactor system.

Improvement of the catalytic performance of hybrid nanocomposite based on phosphate-benzimidazole in Knoevenagel condensation

In this work, we have developed a simple and very effective experimental strategy for the reaction of Knoevenagel via the condensation of aromatic aldehydes substituted with active methylene compounds in the presence of hybrid nanocomposites xMCl₂-yNaPO₃ (MCl₂ = 2,2′-dibenzimidazolyl butane dichlorhydrates), under ecological conditions. The Phosphate-Benzimidazole hybrid nanocomposite as heterogeneous catalysts has demonstrated a high catalytic activity for the Knoevenagel condensation in ethanol as an ecological solvent. It has several advantages such as light reaction conditions, a simple and ecological working procedure. Meanwhile, xMCl₂-yNaPO₃ can be recovered by simple filtration and this catalytic system having an interesting lifetime (five cycles) with no decrease in activity.

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

The calcination process is a crucial step during SBA-15 and KIT-6 synthesis. It is used to completely remove the organic template and condense silanol groups, and it allows the determination of the textural and physical properties of these materials, depending on the adopted conditions. Moreover, calcination influences the number of silanols available on the surface of the material. The concentration of silanols is important if these materials were synthesized for use in adsorption or functionalization. To understand and optimize the silanol groups of SBA-15 and KIT-6, in this study, the temperature and time calcination parameters were varied. The experiments were performed at 300, 400, and 500 °C for 300, 400, and 500 min. The results show that the ideal temperature to preserve the silanol groups is 300 °C, but to optimize the textural properties, it is better to calcine these molecular sieves at 400 °C. A calcination for 10 h did not give better results than a calcination for 5 h, demonstrating that the former duration is excessive for use.

Alumina grafted SBA-15 sustainable bifunctional catalysts for direct cross-coupling of benzylic alcohols to diarylmethanes

AlSBA-15 catalysts possessing Brønsted acid and Lewis acid–base bifunctionalities catalyze the direct arylation of benzyl alcohols to diarylmethanes with an 85% product yield through C–O bond activation.

Efficient synthesis of butyl levulinate from furfuryl alcohol over ordered mesoporous Ti-KIT-6 catalysts for green chemistry applications

Here we describe the synthesis of butyl levulinate by alcoholysis of furfuryl alcohol with n-butanol over a series of titanium incorporated mesoporous KIT-6 molecular sieve catalysts prepared by a simple sol–gel treatment.

Design and fabrication of mesoporous heterogeneous basic catalysts

Recent advances in mesoporous solid bases were reviewed, and fundamental principles of how to fabricate efficient basic catalysts were highlighted.

Enhanced catalytic performance for metathesis reactions over ordered tungsten and aluminum co-doped mesoporous KIT-6 catalysts

W-Al-KIT-6 (Si/Al = 10) with high dispersion of active W species and moderate acidity shows highest activity and selectivity to propene.