Catalytic activity of Pt loaded zeolites for hydroisomerization of n-hexane using supercritical CO2

Al-Rawi, U.A., Sher, F. ORCID: 0000-0003-2890-5912, Hazafa, A., Rasheed, T., Al-Shara, N.K., Lima, E.C. and Shanshool, J., 2020. Catalytic activity of Pt loaded zeolites for hydroisomerization of n-hexane using supercritical CO2. Industrial and Engineering Chemistry Research, 59 (51), pp. 22092-22106. ISSN 0888-5885

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Abstract

The present study investigates the synthesis of novel strontium (Sr) and barium (Ba) modified crystalline zeolites including Zeolite Socony Mobil-5 (ZSM-5) and Mordenite (MOR) utilizing a batchwise ion-exchange method with an appropriate chloride solution of 3 N at pH 7.2 and 50 °C. Modified zeolites (Ba-ZSM-5 and Ba-MOR, Sr-ZSM-5 and Sr-MOR) were coated with an inert metal (Pt) by a novel supercritical CO2 method using PtMe2COD as a precursor for n-hexane hydroisomerization in a microreactor unit at different temperatures (250–325 °C), H2/HC ratios of 3, 6, and 9, and a pressure of 5 bar. The acidic and physical features of Pt loaded zeolites were systematically characterized using FT-IR, XRD, BET surface area measurements, TGA, and TEM techniques. It is found that the metal loading in scCO2 results in more uniform and very small metal nanoparticle (1.37 nm) dispersion with high stability after reduction. It is also revealed that high loading pressure in scCO2 (280–300 bar) results in higher catalytic activity and surface area. The maximum conversion and selectivity of about 80 and 90% were achieved for n-hexane isomerization at 275 °C and a H2/HC ratio of 6 for Pt/Sr-ZSM-5 catalyst. Results reported that Pt loaded over all zeolites (H-MOR, Sr-MOR, Ba-MOR, H-ZSM-5, Ba-ZSM-5, and Sr-ZSM-5) by the scCO2 method showed the minimum production of cracking products (C1–C5) and maximum isomeric products including iso-C6 isomers (2,2-DMB, 2,3-DMB, 2-MP, and 3-MP). Furthermore, the overall results of the rate of reaction revealed that Pt/Sr-ZSM-5 and Pt/Ba-ZSM-5 catalysts showed a better rate of isomerization (46.44%) and conversion (47%) for n-hexane at 300 °C and a H2/HC ratio of 9 with a minimum rate of cracking. However, it is concluded that the small, pored size Pt loaded ZSM-5 zeolite showed the highest catalytical activity compared to large pored MOR zeolite making it of great interest for diesel and gasoline formation in the oil refining industry.

Item Type: Journal article
Publication Title: Industrial and Engineering Chemistry Research
Creators: Al-Rawi, U.A., Sher, F., Hazafa, A., Rasheed, T., Al-Shara, N.K., Lima, E.C. and Shanshool, J.
Publisher: American Chemical Society (ACS)
Date: 23 December 2020
Volume: 59
Number: 51
ISSN: 0888-5885
Identifiers:
NumberType
10.1021/acs.iecr.0c05184DOI
1567853Other
Rights: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial and Engineering Chemistry Research, copyright © 2020 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.iecr.0c05184
Divisions: Schools > School of Science and Technology
Record created by: Laura Ward
Date Added: 25 Jul 2022 14:52
Last Modified: 25 Jul 2022 14:52
URI: http://irep.ntu.ac.uk/id/eprint/46709

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