Jump to main content
Jump to site search

Issue 2, 2015
Previous Article Next Article

Direct production of indoles via thermo-catalytic conversion of bio-derived furans with ammonia over zeolites

Author affiliations

Abstract

In this study we demonstrate that indoles can be directly produced by thermo-catalytic conversion of bio-derived furans with ammonia over zeolite catalysts. MCM-41, β-zeolite, ZSM-5 (Si/Al = 50) and HZSM-5 catalysts with different Si/Al ratios (Si/Al = 25, 50, 63, 80) were screened and HZSM-5 with an Si/Al ratio of 25 showed the best reactivity for indole production due to the desired pore structure and acidity. Temperature displayed a significant effect on the product distribution. The maximum yield of indoles was obtained at moderate temperatures around 500 °C. The weight hourly space velocity (WHSV) of furan to catalyst investigation indicated that a lower WHSV could cause the overreaction of furan over the catalyst to produce more aniline and pyridines, while a higher WHSV would cause the incomplete reaction of furan. Because ammonia served as both a reactant and a carrier gas, to supply sufficient reactants and keep the desired reaction time, an appropriate ammonia to furan molar ratio was important for furan conversion to indoles. Under optimized conditions, the highest total carbon yield of indoles and their selectivity in the N-containing chemicals were 32% and 75%, respectively. 2-Methylfuran and the mixture of furan and 2-methylfuran were also studied, which demonstrated that more alkyl indoles could be selectively obtained via the coupling reaction of different bio-derived furans. Ring opening of the furan is a more favorable mechanism compared to the Diels–Alder mechanism, and the pyrrole reacting with furan is the more favorable pathway compared to pyrrole reacting with pyrrole based on our experimental and theoretical calculations.

Graphical abstract: Direct production of indoles via thermo-catalytic conversion of bio-derived furans with ammonia over zeolites

Back to tab navigation

Supplementary files

Publication details

The article was received on 17 Nov 2014, accepted on 24 Nov 2014 and first published on 24 Nov 2014


Article type: Paper
DOI: 10.1039/C4GC02250E
Author version available: Download Author version (PDF)
Citation: Green Chem., 2015,17, 1281-1290
  •   Request permissions

    Direct production of indoles via thermo-catalytic conversion of bio-derived furans with ammonia over zeolites

    L. Xu, Y. Jiang, Q. Yao, Z. Han, Y. Zhang, Y. Fu, Q. Guo and G. W. Huber, Green Chem., 2015, 17, 1281
    DOI: 10.1039/C4GC02250E

Search articles by author

Spotlight

Advertisements