Silica functionalised sulphonic acid groups: synthesis, characterization and catalytic activity in acetalization and acetylation reactions

Designing bifunctional acid–base mesoporous hybrid catalysts for cascade reactions

“…Upon the oxidation with H 2 O 2 , necessary to convert thiols to suphonic 30 groups, the peak at 27 ppm disappeared and contemporarily new signals at 54 ppm, due to C1, and at 18 ppm due to C2 adjacent to the -SO 3 H groups, appeared (curves c-e), suggesting a complete oxidation of thiols in -SO 3 H groups. 41,42,46,47 The signal due to sulfonic acids is also present after the grafting of the DMAN 35 organic base onto the mesoporous silica (curve e) and this confirms that the post-synthetic procedure used to graft the organic base does not affect the strong acid sites. Additionally, 29 Si MAS NMR spectra confirm that the DMAN fragments and MPTES are not only intact after the synthesis of 60 the bifunctional hybrids but are also incorporated covalently into the ordered and non-ordered porous network bounded to inorganic silica units.…”

“…500-550ºC (III). 41,42 In fact, the DTA curves of SO 3 H/SiO 2 -5 and SO 3 H/OMS-5 (Section C, curves c and d) have evidenced that the alkyl-sulfonic acid groups decompose at ca. 500-550ºC (III).…”

Preparation of polyamide 6/silica nanocomposites from silica surface initiated ring-opening anionic polymerization

“…On the other hand, there is a distinct mass loss region between 200 and 600°C for SiO 2 -NCO, caprolactam-functionalized silicas, and PA6/silica nanocomposites with different polymer weight proportions. However, it has to be pointed out that part of the weight loss of the silica particles is due to the continued condensation reaction and associated water loss [28]. If the weight retention of the residue at 700°C is used as the reference, the weight retention of SiO 2 -NCO at 700°C is about 68 wt%.…”

Zr-modified hierarchical mordenite as heterogeneous catalyst for glycerol esterification

“…Used cooking oil (UCO) is currently one of the most attractive feedstocks for the production of biodiesel [1][2][3][4][5], mostly due to the low market value of the feedstock. Glycerol is generated as a byproduct in conventional biodiesel production and can be converted to various valuable chemicals through numerous routes such as etherification [6], hydrogenolysis [7], oxidation [8], transesterification [9] and dehydration [10]. Besides, glycerol can be esterified with acetic acid to obtain valuable products of mono-, di-and triacetyl glycerol (named as MAG, DAG and TAG, respectively), which have found versatile industrial applications [11].…”