TY - JOUR
T1 - Citronellal cyclisation over heteropoly acid supported on modified montmorillonite catalyst
T2 - effects of acidity and pore structure on catalytic activity
AU - Shah, Abdul Karim
AU - Park, Sungsoo
AU - Khan, Hassnain Abbas
AU - Bhatti, Umair Hassan
AU - Kumar, Praveen
AU - Bhutto, Abdul Waheed
AU - Park, Yeung Ho
N1 - Publisher Copyright:
© 2018, Springer Science+Business Media B.V., part of Springer Nature.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Citronellal cyclisation to isopulegol is an important intermediate step in the production of menthol. Several heteropoly acids (PTA) supported on modified montmorillonite (MM) catalysts were synthesized and then tested in cyclisation reactions. The prepared samples were characterized by XRD, ICP-OES, FTIR, N2 sorption, NH3-TPD, pyridine adsorption, amine titration and FE-SEM techniques. Effects of post-treatment were studied on montmorillonite pore structure, acidity and catalytic activity. The catalytic activity and isopulegol selectivity improved with acid-treatment and PTA loading. The amount of Lewis acidity of montmorillonite was enhanced with acid-treatment and PTA impregnation. In cyclisation, highest catalytic activity (31.87 mmol cat g−1 min−1) was achieved with 96% isopulegol yield in the use of 20% PTA-MM catalyst. The highest catalytic activity and selectivity were obtained in the presence of higher acidity and strong Lewis acidic sites, whereas effects of pore structure blockage seemed minor. The catalytic activity further decreased with the loss of active acidic sites (L and B) due to PTA decomposition with calcination at a higher temperature.
AB - Citronellal cyclisation to isopulegol is an important intermediate step in the production of menthol. Several heteropoly acids (PTA) supported on modified montmorillonite (MM) catalysts were synthesized and then tested in cyclisation reactions. The prepared samples were characterized by XRD, ICP-OES, FTIR, N2 sorption, NH3-TPD, pyridine adsorption, amine titration and FE-SEM techniques. Effects of post-treatment were studied on montmorillonite pore structure, acidity and catalytic activity. The catalytic activity and isopulegol selectivity improved with acid-treatment and PTA loading. The amount of Lewis acidity of montmorillonite was enhanced with acid-treatment and PTA impregnation. In cyclisation, highest catalytic activity (31.87 mmol cat g−1 min−1) was achieved with 96% isopulegol yield in the use of 20% PTA-MM catalyst. The highest catalytic activity and selectivity were obtained in the presence of higher acidity and strong Lewis acidic sites, whereas effects of pore structure blockage seemed minor. The catalytic activity further decreased with the loss of active acidic sites (L and B) due to PTA decomposition with calcination at a higher temperature.
KW - Acidity
KW - Citronellal cyclisation
KW - Heteropoly acids
KW - Isopulegol
KW - Montmorillonite
KW - Pore structure
UR - http://www.scopus.com/inward/record.url?scp=85043473866&partnerID=8YFLogxK
U2 - 10.1007/s11164-017-3237-4
DO - 10.1007/s11164-017-3237-4
M3 - Article
AN - SCOPUS:85043473866
SN - 0922-6168
VL - 44
SP - 2405
EP - 2423
JO - Research on Chemical Intermediates
JF - Research on Chemical Intermediates
IS - 4
ER -