Jump to main content
Jump to site search

Issue 13, 2018
Previous Article Next Article

A CaMnAl-hydrotalcite solid basic catalyst toward the aldol condensation reaction with a comparable level to liquid alkali catalysts

Author affiliations

Abstract

In a number of heterogeneous catalysis processes, the promotion effect toward active sites is of vital importance and remains a challenge to obtain largely-improved catalytic performance. Herein, rehydrated Ca4MnxAl-layered double hydroxides (denoted as re-Ca4MnxAl-LDH) were prepared based on a structure memory effect of LDH precursors, which exhibited extremely high heterogeneous catalytic performance for the aldol condensation reaction, with the assistance of the promotion effect of Mn. A combination study including XRD, EXAFS, XPS, CDCl3-FTIR and DFT calculations confirms that re-Ca4MnxAl-LDH samples with Ca–O–MnIV structure show a highly-exposed Ca2+ s-orbital and strengthened coordination between Ca2+ with 7-fold OH, providing a weakened Brønsted basic site compared with the reference sample re-Ca4Al-LDH. The optimized re-Ca4Mn0.5Al-LDH catalyst exhibits prominent catalytic performance toward the condensation of isobutyraldehyde (IBD) and formaldehyde (FA) to produce hydroxypivaldehyde (HPA), with a HPA yield of 70.3%. This is significantly higher than re-Ca4Al-LDHs (63.3%) and even comparable to the level of liquid alkali catalysts (73.2%). Studies on the structure–property correlation reveal that the weakened basic site originating from Ca–O–MnIV serves as a promoted active center, which accelerates the product desorption and thus largely improves HPA selectivity. This promoted re-Ca4Mn0.5Al-LDH catalyst can be potentially applied as a promising candidate in heterogeneous aldol condensation reactions.

Graphical abstract: A CaMnAl-hydrotalcite solid basic catalyst toward the aldol condensation reaction with a comparable level to liquid alkali catalysts

Back to tab navigation

Supplementary files

Publication details

The article was received on 16 Mar 2018, accepted on 02 Jun 2018 and first published on 04 Jun 2018


Article type: Paper
DOI: 10.1039/C8GC00851E
Citation: Green Chem., 2018,20, 3071-3080
  •   Request permissions

    A CaMnAl-hydrotalcite solid basic catalyst toward the aldol condensation reaction with a comparable level to liquid alkali catalysts

    W. Bing, H. Wang, L. Zheng, D. Rao, Y. Yang, L. Zheng, B. Wang, Y. Wang and M. Wei, Green Chem., 2018, 20, 3071
    DOI: 10.1039/C8GC00851E

Search articles by author

Spotlight

Advertisements