Hierarchical SAPO‐34 Architectures with Tailored Acid Sites using Sustainable Sugar Templates

Abstract

In a distinct, bottom‐up synthetic methodology, monosaccharides (fructose and glucose) and disaccharides (sucrose) have been used as mesoporogens to template hierarchical SAPO‐34 catalysts. Detailed materials characterization, which includes solid‐state magic angle spinning NMR and probe‐based FTIR, reveals that, although the mesopore dimensions are modified by the identity of the sugar template, the desirable acid characteristics of the microporous framework are retained. When the activity of the hierarchical SAPO‐34 catalysts was evaluated in the industrially relevant Beckmann rearrangement, under liquid‐phase conditions, the enhanced mass‐transport properties of sucrose‐templated hierarchical SAPO‐34 were found to deliver a superior yield of ϵ‐caprolactam.

Affecting the Formation of the Micro‐structure and Meso/macro‐structure of SAPO‐34 zeolite by Amphipathic Molecules

“…The thermogravimetric analyses (TGA) curve (Figure S7) of CZ‐6 shows that the content of template molecules in the as‐made CZ‐6 is approximately 19.6 wt %, larger than that of conventional SAPO‐34 (18.2 wt %), due to the additional C6 molecules in CZ‐6. Two obvious weight losses can be recognized from TGA curves: a low‐temperature weight loss before 150 °C and a high‐temperature weight loss after 300 °C, which are ascribed to desorption of water and templates, respectively . The template molecule begins to decompose after 300 °C, which is obviously higher than the crystallization temperature, so the TGA curve also give the evidence that C6 molecules keep intact during the entire synthetic process.…”

Probing the Design Rationale of a High‐Performing Faujasitic Zeotype Engineered to have Hierarchical Porosity and Moderated Acidity

“…Due to steric hindrance (kinetic diameter = 10.5 ), 2,6-dTBP can only interact with the most accessible acid sites,for example those located on the catalyst surface,o rw ithin the mesopores. [52,[54][55][56] In the FTIR region associated with 2,6-dTBP aromatic ring-modes (1700-1540 cm À1 )two peaks were observed. [52,[54][55][56] Ah igher energy band, centered at 1616 cm À1 ,characterized the protonated 2,6-dTBPH + species, and hence Brønsted acid sites.The n 8a mode at 1576 cm À1 was attributed to weaker,hydrogen-bonding interactions between 2,6-dTBP and the Si-OH or P-OH sites in SAPO-37 catalysts, which could be removed by outgassing at 298 K. Thes ame probe molecules were also adsorbed on MP SAPO-37 ( Figure S6 and S7).…”

“…[52,[54][55][56] In the FTIR region associated with 2,6-dTBP aromatic ring-modes (1700-1540 cm À1 )two peaks were observed. [52,[54][55][56] Ah igher energy band, centered at 1616 cm À1 ,characterized the protonated 2,6-dTBPH + species, and hence Brønsted acid sites.The n 8a mode at 1576 cm À1 was attributed to weaker,hydrogen-bonding interactions between 2,6-dTBP and the Si-OH or P-OH sites in SAPO-37 catalysts, which could be removed by outgassing at 298 K. Thes ame probe molecules were also adsorbed on MP SAPO-37 ( Figure S6 and S7). Significantly,from the relative intensities of the characteristic modes,t he FTIR spectra showed that considerably more 2,6-dTBP was adsorbed in HP SAPO-37 than MP SAPO-37, demonstrating the improved accessibility of the HP framework via the mesopores.…”

A smart use of biomass derivatives to template an ad hoc hierarchical SAPO-5 acid catalyst

“…Glucose was chosen as benchmark substrate because of its similarity with the employed biomass-derived sugar templates. According to this smart approach, MsB have been used as sustainable and low-cost mesoporogens for the preparation of hierarchical porous materials, 12,13 avoiding the use of sophisticated and expensive templates. Indeed, the mixture of MsB used to template the inorganic structure was obtained through a ash MW-assisted conversion process (2 min) of a cost-effective feedstock such as post-harvest tomato plants.…”

“…Subsequently, pyridine and 2,4,6-trimethylpyridine (2,4,6-TMP or collidine) with larger kinetic diameters, were adsorbed. 12,17,18 The FTIR difference spectra of NH 3 (Fig. 3A), pyridine ( Figure 3B) and 2,4,6-TMP ( Fig.…”