Malaysian Journal of Analytical Sciences Vol 24 No 2 (2020): 218 - 226

 

 

 

 

DEACIDIFICATION OF NAPHTHENIC ACIDS FROM PETROLEUM CRUDE OILS USING 2-METHYLIMIDAZOLE IN PEG(400) WITH THE AID OF Ni/Ce/Al₂O₃ and Cu/Ce/Al₂O₃ CATALYSTS

 

(Deasidifikasi Asid Naftenik dari Minyak Mentah Petroleum menggunakan 2-Metilimidazola dalam PEG(400) dengan Bantuan Pemangkin Ni/Ce/Al₂O₃ dan Cu/Ce Al₂O₃)

 

Norshahidatul Akmar Mohd Shohaimi¹*, Nor Shafira Hassan¹, Ahmad Zamani Ab Halim², Nurasmat Mohd Shukri³, Nor Hakimin Abdullah⁴

 

¹Faculty of Applied Sciences,

Universiti Teknologi MARA Pahang, Bandar Tun Abdul Razak Jengka, Pahang, Malaysia

²Faculty of Industrial Sciences & Technology,

Universiti Malaysia Pahang, 26300 Gambang, Kuantan, Pahang, Malaysia

³School of Health Sciences,

Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia

⁴Advanced Materials Research Centre (AMRC), Faculty of Bioengineering and Technology,

Universiti Malaysia Kelantan, Locked Bag 100, 17600 Jeli, Kelantan, Malaysia

 

*Corresponding author:  akmarshohaimi@uitm.edu.my

 

 

Received: 20 November 2019; Accepted: 3 March 2020

 

 

Abstract

The presence of carboxylic acid derivative compound in crude oil adversely contributes to major corrosion in oil pipelines and distillation units installed in crude oil refineries. The acidity level in crude oil is measured based on the total acid number (TAN). Methods that are commonly used to remove naphthenic acid (NA) from crude oil, such as dilution and caustic washing, have several drawbacks, including emulsion formation, high temperature, and massive use of solvent. In order to overcome these shortcomings, catalytic deacidification method had been developed to reduce the TAN value in acidic crude oil by using basic chemical, along with the aid of metal oxide catalyst. In this study, crude oil from Petronas Penapisan Melaka was evaluated. The parameters studied were reagent concentration, reaction temperature, catalyst loading, calcination temperature, and reusability of potential catalyst. The basic chemical used was 2-methylimidazole in polyethylene glycol (PEG 400) with concentrations of 100, 500, 1000, and 1500 ppm. Next, Ce was used as base for the catalyst with both Ni and Cu serving as dopant. The potential catalysts were characterised via Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA) to determine their physicochemical properties. The outcomes showed that the Cu/Ce catalyst met the Petronas requirement as the TAN value reduced to 0.93 mg KOH/g from the original TAN value of 3.93 mg KOH/g. As for Ni/Ce catalyst, the TAN value reduced to 1.03 mg KOH/g. The TGA results revealed the total weight loss of Cu/Ce = 23.40% and Ni/Ce = 25.22% due to complete removal of impurities from the catalysts. The reaction temperature was set at 27  °C, while the catalyst calcination temperature was fixed at 1000  °C, and seven beads of catalyst loading had been employed. It can be concluded that catalytic deacidification method with the aid of Cu/Ce was indeed efficient in removing NA from the acidic crude oil, thus lowering the TAN value to less than 1 mg KOH/g.

 

Keywords:  deacidification, petroleum crude oil, naphthenic acid, catalyst

 

Abstrak

Kehadiran sebatian derivatif asid karboksilik dalam minyak mentah boleh menyumbang kepada hakisan utama dalam paip pemproses minyak dan unit penyulingan dalam kilang minyak mentah. Tahap keasidan dalam minyak mentah diukur dengan jumlah nombor asid (TAN). Kaedah-kaedah yang biasanya digunakan untuk mengeluarkan asid naftenik (NA) dari minyak mentah seperti pencairan dan pencuci kaustik mempunyai kelemahan sendiri seperti pembentukan emulsi, suhu tinggi dan penggunaan pelarut yang banyak. Untuk mengatasi masalah ini, kaedah deasidifikasi pemangkin telah dicipta bagi mengurangkan nilai TAN dalam minyak mentah berasid dengan menggunakan bahan kimia asas dengan bantuan pemangkin logam oksida. Dalam kajian ini, minyak mentah dari Petronas Penapisan Melaka digunakan. Parameter yang dikaji adalah kepekatan reagen, suhu tindak balas, jumlah pemangkin, suhu pemangkin dan kebolehgunaan semula pemangkin yang berpotensi. Bahan kimia asas yang digunakan ialah 2-metilimidazola dalam polietilena glikol (PEG 400) dengan kepekatan 100, 500, 1000 dan 1500 ppm. Ce digunakan sebagai asas pemangkin dengan Ni dan Cu bertindak sebagai dopan. Pemangkin berpotensi menjalani kaedah pencirian seperti spekstroskopi inframerah transformasi Fourier (FTIR) dan analisis termogravimetri (TGA) untuk sifat fiziko-kimianya. Hasilnya menunjukkan bahawa pemangkin Cu/Ce memenuhi keperluan Petronas kerana nilai TAN dikurangkan kepada 0.93 mg KOH/g dari nilai TAN asal 3.93 mg KOH/g. Bagi pemangkin Ni/Ce, nilai TAN dikurangkan kepada 1.03 mg KOH/g. Keputusan TGA menunjukkan penurunan berat badan Cu/Ce = 23.40% dan Ni/Ce = 25.22% disebabkan oleh pembuangan lengkap bahan pencemar dalam mangkin. Suhu tindak balas yang digunakan adalah 27 °C dengan suhu pembakaran pemangkin 1000 °C dan 7 biji jumlah pemangkin. Dapat disimpulkan bahawa kaedah deasidifikasi pemangkin dengan bantuan Cu/Ce adalah cekap dalam menghilangkan NA dari minyak mentah berasid sehingga menurunkan nilai TAN kurang dari 1 mg KOH/g.

 

Kata kunci:  deasidifikasi, minyak mentah petroleum, asid naftenik, pemangkin

 

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