Rekha Yadav

Mesoporous SAPO-5 (MESO-SAPO-5): a potential catalyst for hydroisomerisation of 1-octene

Mesoporous silicoaluminophosphate was assembled from microporous SAPO-5 secondary building unit precursors. The resultant material possessed both mesoporous channel properties and microporous wall properties. The catalyst showed promising results for vapour phase isomerisation of 1-octene. The presence of strong acidic sites favoured the formation of considerable skeletal isomerised products at elevated temperatures (400–450 °C). However, the catalytic conversion remains constant and active for several hours.

In-situ preparation of functionalized molecular sieve material and a methodology to remove template.

A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol.

Preparation of mesoporous silicoaluminophosphate using ammonium hydroxide as the base and its catalytic application in the trans-alkylation of aromatics

Hierarchical mesoporous silicoaluminophosphate (M-S-34-N) was assembled for the first time in the presence of ammonium hydroxide as the base. The resulting materials were subsequently stabilized via vapor-phase treatment in presence of tetraethylorthosilicate (TEOS). N2 sorption analysis and pyridine desorption studies revealed that materials possess uniform mesoporous channel with high surface area, large pore volume, and strong Lewis acidity, respectively. The local environment of aluminum and silicon were followed with solid-state 27Al, and 29Si MAS NMR spectral studies, which indicates their successful framework incorporation. The strong acidity present on the resultant M-S-34-N-VPT facilitates for liquid-phase trans-alkylation of naphthalene using 1,3-diisopropylbenzene.

Isopropylation of 2-naphthol over mesoporous silicoaluminophosphate-37 (MESO-SAPO-37): the effect of bond dissociation energy on product distribution

The vapor phase isopropylation of 2-naphthol (2-NP) with isopropyl alcohol (IPA) in the presence of recently developed mesoporous silicoaluminophosphate assembled from a microporous SAPO-37 precursor (MESO-SAPO-37) was investigated. The bond dissociation energy calculation revealed that the reaction proceeds by O-alkylation followed by rearrangment into C-alkylated products. The presence of a phenolic hydroxyl group facilitates o- and p-directing (1- and 6-positions of 2-NP) and favors 1- and 6-isopropyl-2-naphthols as the major products. The moderately acidic MESO-SAPO-37 showed a maximum 2-NP conversion of 60% achieved with a selectivity of 60% for 6-isopropyl-2-naphthol (6-IP-2-NP) under optimum reaction conditions (T = 250 °C, WHSV = 9.4 h−1 and a 2-NP : IPA ratio of 1 : 20).

Aluminium Oxide Supported on SBA-15 Molecular Sieves as Potential Lewis Acid Catalysts for Epoxide Ring Opening Using Aniline

AbstractA series of aluminium oxide (Al2O3)-supported SBA-15 molecular sieves were prepared using a one-step wet-impregnation method. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared spectroscopy and ammonia TPD were used to investigate the structures and chemical natures of the surface-bound species. The FT-IR studies of metal-impregnated SBA-15 materials revealed strong covalent interaction of Al2O3 on SBA-15 materials with strong Lewis acidic properties, evident from ammonia-TPD studies. The metal oxide-supported SBA-15 catalysts are active for epoxide ring opening with aniline at room temperature, and showed remarkably high stability and selectivity towards mono-alkylated products (about 86%) viz., 1-(phenylamino)propan-2-ol and 2-(phenylamino)propan-1-ol. The catalytic activities remained intact after several recycles. The observed activities and selectivities were compared with other metal oxide-loaded SBA-15 catalysts obtained by similar preparation methods.Graphical AbstractAluminium oxide supported SBA-15 molecular sieves were prepared using a one-step wet-impregnation method. The materials showed strong Lewis acidic sites and promising catalytic activity for epoxide ring opening with aniline at room temperature.