Vol.:(0123456789) Research on Chemical Intermediates https://doi.org/10.1007/s11164-020-04139-2 1 3 Preparation and characterization of Ca‑modifed Co/ Al 2 O 3 and its catalytic application in the one‑pot synthesis of 4H‑pyrans Sakineh Khaledi, et al. [full author details at the end of the article] Received: 7 February 2020 / Accepted: 27 March 2020 © Springer Nature B.V. 2020 Abstract In this research, Co/Ca–Al 2 O 3 composite as a heterogeneous nanocatalyst was syn- thesized by the co-precipitation method. The efect of Ca addition on the textural properties and the catalytic activity was investigated. The results show that the spe- cifc surface area and the particle size of the catalyst were infuenced by the addition of Ca as well as the catalytic activity of the Co/Al 2 O 3 oxide catalyst was increased. The catalyst was characterized by XRD, SEM, EDS, TEM and BET surface area analysis. The catalytic activity of Co/Ca–Al 2 O 3 was investigated in the synthesis of 4H-pyrans. The Co/Ca–Al 2 O 3 showed better catalytic activity than Al 2 O 3 and Co/Al 2 O 3 . The catalyst can be recycled and reused without a signifcant structural change or considerable decrease in its activity. Graphic abstract CHO R + CN CN H 3 C O O O H 3 C H 3 C O O H 3 C H 3 C CN NH 2 R EtO H 3 C O O CN NH 2 R 1a-1l 2a-2m O H 3 CH 2 CO Al Ca Co Keywords Co/Ca–Al 2 O 3 nanocatalyst · 4H-pyrans · Multicomponent reactions · Co-based catalyst · Heterogeneous catalysis