Maximizing the Accessibility of Active Species in Weakly Acidic Zr‐SBA‐15 Materials

Abstract

Weakly acidic Zr‐SBA‐15 materials were synthesized by using a novel method to maximize the accessibility of zirconium sites in view of their catalytic applications. Synthesized materials at different ageing temperatures were characterized by means of several techniques such as XRD, N2 physisorption, TEM, ammonia temperature‐programmed desorption, and X‐ray photoelectron spectroscopy and subsequently used in a test acid‐catalyzed process such as the microwave‐assisted alkylation of anisole with benzyl chloride. Reaction results revealed the very high catalytic activity of the prepared Zr‐SBA‐15 materials, which depended mostly on the accessibility of the supported zirconium species and their speciation.

Vapor phase esterification of levulinic acid over ZrO2/SBA-15 catalyst

“…The pore size distribution curves (inset of Figure-2) indicates that majority of the pores are concentrated at around 7 nm even though this value is different from the average pore size (~6 nm). Generally, the pore wall thickness of SBA-15 type mesoporous materials will be lower than average pore size, but there are instances where both values are more or less same [24][25][26].…”

Zr-SBA-15 Lewis Acid Catalyst: Activity in Meerwein Ponndorf Verley Reduction

“…Our previous investigations on the synthesis and use of Zr-SBA-15 have revealed a highly active catalyst in several acid-driven reactions [25][26][27][28]. The high activity of this material has been attributed not to the acid strength of the supported active species weak Lewis acid sites, but to the high accessibility of the same, which occupy accessible locations on the surface of the mesopores.…”

Environmentally friendly lubricants through a zero waste process

“…However, one of the main drawbacks of Zr based catalysts is their low surface area making the Zr site not easily accessible to reactants thus promoting intensive efforts to improve this parameter by using meso-structured silica with very high surface area, open porous structure and narrow pore size distribution as supports [21]. In particular SBA 15 silica supports with a tunable large sized pore structure and high hydrothermal stability has been often used as the support for zirconocene exchanged materials able to promote both the transesterification of raw vegetable oil and the esterification of fatty acids with methanol to produce Biodiesel at 200°C and with a MeOH to oil molar ratio 30:1 [22][23][24].…”