Malaysian Journal of Analytical Sciences Vol 20 No 2 (2016): 296 - 302

 

 

 

OXIDATION OF COMMERCIAL PETRONAS DIESEL WITH TERT-BUTYL HYDROPEROXIDE OVER POLYMOLYBDATE ALUMINA SUPPORTED CATALYST MODIFIED WITH ALKALINE EARTH METALS

 

(Pengoksidaan Diesel Komersial Petronas dengan Tert-Butil Hidroperoksida bersama Pemangkin Polimolibdenum Diubahsuai dengan Logam Alkali)

 

Wan Nazwanie Wan Abdullah, Rusmidah Ali*, Wan Azlee Wan Abu Bakar

 

Department of Chemistry, Faculty of Science,

Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia

 

*Corresponding author: rusmidah@kimia.fs.utm.my

 

 

Received: 9 December 2014; Accepted: 9 October 2015

 

 

Abstract

Due to strict environmental legislation for ultra-low sulfur diesel fuels, increasing technical and operational challenges are imposed to conventional hydrodesulfurization (HDS) technology. Therefore, catalytic oxidative desulfurization (Cat-ODS) has been suggested to be an alternative method to replace a conventional method which is hydrodesulfurization. In this study, catalytic oxidation of commercial diesel was performed using an oil-soluble oxidant, tert-butyl hydroperoxide (TBHP), over polymolybdate supported on alumina MoO₃-PO₄/Al₂O₃ catalyst. A commercial Petronas diesel with 440 ppmw of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by (GC-FPD). Alkaline earth metals, such as Calcium (Ca), Barium (Ba) and Strontium (Sr) were introduced on the surface of MoO₃-PO₄/Al₂O₃. The results showed that the catalytic activity decreased in the order, Ca/MoO₃-PO₄/Al₂O₃>Sr/MoO₃-PO₄/Al₂O₃> Ba/MoO₃-PO₄/Al₂O₃. The Ca/MoO₃-PO₄/Al₂O₃ catalyst was characterized by XRD and FESEM. XRD results showed that the best catalyst was highly amorphous while FESEM micrograph illustrated an aggregation and agglomeration of various particle sizes. The catalytic activity of Ca/MoO₃-PO₄/Al₂O₃ catalyst with various Ca/Mo ratios were also studied. When the Ca/Mo ratio was 15:85, the sulfur removal  was the highest (79%) at 45ºC, 30 min and O/S molar ratio 3.0 with solvent = dimetylformamide (DMF), diesel/solvent ratio = 1.0.

 

Keywords: Oxidative desulfurization, commercial diesel, tert-butyl hydroperoxide, alkaline earth metals, polymolybdate, dimetylformamide

 

Abstrak

Disebabkan undang-undang alam sekitar yang ketat untuk bahan api sulfur diesel ultra-rendah, peningkatan cabaran teknikal dan operasi dikenakan kepada hydropenyahsulfuran konvensional teknologi (HDS). Oleh itu, penyahsulfuran oksidatif mengunakan pemangkin (Cat-ODS) telah dicadangkan untuk menjadi satu kaedah alternatif untuk menggantikan kaedah konvensional iaitu hydopenyahsulfuran. Dalam kajian ini, pengoksidaan diesel komersial telah dijalankan menggunakan oksida larut minyak, tert-butil hidroperoksida (TBHP) dan  mangkin molibdena berpenyokong alumina, MoO₃-PO₄/Al₂O₃. Diesel komersial Petronas yang mengandungi sulfur 440 ppmw telah digunakan untuk menilai penyahsulfuran. Selain itu, peratusan penyingkiran sulfur telah diukur menggunakan (GC-FPD). Logam alkali, seperti Kalsium (Ca), Barium (Ba) dan Strontium (Sr) telah dicelup pada permukaan MoO₃-PO₄/Al₂O₃ pemangkin. Hasil kajian menunjukkan bahawa aktiviti pemangkin menurun mengikut susunan, Ca/MoO₃-PO₄/Al₂O₃ > Sr/MoO₃-PO₄/Al₂O₃ > Ba/MoO₃-PO₄/Al₂O₃. Pemangkin Ca/MoO₃-PO₄/Al₂O₃ telah dicirikan menggunakan XRD dan FESEM. Keputusan XRD menunjukkan pemangkin yang terbaik adalah sangat amorfus manakala FESEM mikrograf menggambarkan satu aglomerasi dalam pelbagai saiz zarah. Aktiviti pemangkin Ca/MoO₃-PO₄/Al₂O₃ dengan pelbagai nisbah Ca/Mo telah juga dikaji. Apabila nisbah Ca/Mo adalah 15:85, penyingkiran sulfur adalah tertinggi (79%) pada keadaan optimum: 45ºC, 30 min dan nisbah O/S molar = 3.0 dengan pelarut = dimetilformamida (DMF), nisbah diesel/pelarut = 1.0.

 

Kata kunci:    penyahsulfuran oksidatif, diesel komersial, tert-butil hidroperoksida, logam alkali, polimolibdena, dimetil-formamida

 

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