Document Type : Research Paper

Authors

• Taleb Eidy ¹
• Seyed Ali Hosseini ²
• Ghasem Marandi ³

¹ M.S. Student, Department of Applied Chemistry, Faculty of Chemistry, Urmia University, Urmia, Iran

² Associate Professor, Department of Organic Chemistry, Faculty of Chemistry, Urmia University, Urmia, Iran

³ Assistant Professor, Department of Organic Chemistry, Faculty of Chemistry, Urmia University, Urmia, Iran

Abstract

The separation of naphthenic acids from crude oil is difficult, and the presence of such materials in crude oil reduces its value. In this work, using catalytic esterification with methanol, naphthenic acids of crude oil were removed to reduce their harmful effects. SnO₂/γ-Al₂O₃ nanocatalyst was synthesized and used to convert naphthenic acids of crude oil in a fixed bed catalytic reactor. The nanocatalyst was characterized by the X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area techniques. The XRD revealed the formation of rutile SnO₂ on alumina, and the FESEM approved that the catalyst is comprised of nanoparticles with a diameter in the range of 50 to 90 nm. The BET indicated that the catalyst has a mesopore structure with a surface area of 213.4 m²·g^–1. The optimal conditions for the catalytic esterification process of naphthenic oil were determined. The temperature of the reduction of the total acid number (TAN) of crude oil ranged from 250 to 360 °C, and the TAN was reduced to less than 0.5 mg KOH/g in this temperature range. A methanol-to-oil ratio (M/O) of 2 wt %, a velocity space of 2.5 h^–1, a reaction temperature of 300 °C, and atmospheric pressure were selected as the optimal conditions for the removal of naphthenic acids. Under these conditions, 83% of naphthenic acids was removed. The study indicated that SnO₂/γ-Al₂O₃ could be a promising nanocatalyst for the reduction of total acid of crude oil under mild conditions.

Highlights

• SnO₂/Al₂O₃ was synthesized as a mesoporous nanocatalyst.
• SnO₂/Al₂O₃ nanocatalyst was used to convert naphthenic acids of crude oil.
• The naphthenic acids were removed by catalytic esterification with methanol to reduce their harmful effects.
• The optimal conditions for the catalytic esterification of naphthenic oils process were determined and under these conditions, 83% of naphthenic acids were removed.

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Keywords

• Crude Oil
• Nano Tin Oxide
• Naphthenic Acids
• Space Velocity
• Total Acid Number

Main Subjects

• Chemical Engineering