A strategy to convert propane to aromatics (BTX) using TiNp grafted at the periphery of ZSM-5 by surface organometallic chemistry

The direct conversion of propane into aromatics (BTX) using modified ZSM-5 was achieved with a strategy of "catalysis by design". In contrast to the classical mode of action of classical aromatization catalysts which are purely based on acidity, we have designed the catalyst associating tw...

Full description

Saved in:
Bibliographic Details
Published inDalton transactions : an international journal of inorganic chemistry Vol. 48; no. 19; pp. 6611 - 662
Main Authors Al Maksoud, Walid, Gevers, Lieven E, Vittenet, Jullian, Ould-Chikh, Samy, Telalovic, Selvedin, Bhatte, Kushal, Abou-Hamad, Edy, Anjum, Dalaver H, Hedhili, Mohamed N, Vishwanath, Vinu, Alhazmi, Abdulrahman, Almusaiteer, Khaled, Basset, Jean Marie
Format Journal Article
Published 15.05.2019
Online AccessGet full text

Cover

Loading…
More Information
Summary:The direct conversion of propane into aromatics (BTX) using modified ZSM-5 was achieved with a strategy of "catalysis by design". In contrast to the classical mode of action of classical aromatization catalysts which are purely based on acidity, we have designed the catalyst associating two functions: One function (Ti-hydride) was selected to activate the C-H bond of propane by σ-bond metathesis to further obtain olefin by β-H elimination and the other function (Brønsted acid) being responsible for the oligomerization, cyclization, and aromatization. This bifunctional catalyst was obtained by selectively grafting a bulky organometallic complex of tetrakis(neopentyl)titanium (TiNp 4 ) at the external surface (external silanol (&z.tbd;Si-OH) group) of [H-ZSM-5 300 ] to obtain [Ti/ZSM-5] catalyst 1 . This metal was chosen to activate the C-H bond of paraffin at the periphery of the ZSM-5 while maintaining the Brønsted acid properties of the internal [H-ZSM-5] for oligomerization, cyclization, and aromatization. Catalyst 2 [Ti-H/ZSM-5] was obtained after treatment under H 2 at 550 °C of freshly prepared catalyst 1 ([Ti/ZSM-5]) and catalyst 1 was thoroughly characterized by ICP analysis, DRIFT, XRD, N 2 -physisorption, multinuclear solid-state NMR, XPS and HR-TEM analysis including STEM imaging. The conversion of propane to aromatics was studied in a dynamic flow reactor. With the pristine [H-ZSM-5 300 ] catalyst, the conversion of propane is very low. However, with [Ti-H/ZSM-5] catalyst 2 under the same reaction conditions, the conversion of propane remains significant during 60 h of the reaction ( ca. 22%). Furthermore, the [Ti-H/ZSM-5] catalyst shows a good and stable selectivity (55%) for aromatics (BTX) of time on stream. With 2 , it was found that the Ti remains at the periphery of the [H-ZSM-5] even after reaction time. The direct conversion of propane into aromatics (BTX) using modified ZSM-5 was achieved with a strategy of "catalysis by design".
Bibliography:10.1039/c9dt00905a
Electronic supplementary information (ESI) available. See DOI
ISSN:1477-9226
1477-9234
DOI:10.1039/c9dt00905a