Document Type : Research Paper

Authors

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.

-         

Keywords

Main Subjects

Anderson, K., Goodrich, P., Hardacre, C., Hussain, A., Rooney, DW., Removal of Naphthenic Acids from Crude Oil using Amino Acid Ionic Liquids, Fuel, Vol.108, p. 715-722, 2013.

Altıokka, M.R.,  Çıtak, A., Kinetics Study of Esterification of Acetic Acid with Isobutanol in the Presence of Amberlite Catalyst, Applied Catalysis A., Vol. 239,  p. 141-148, 2003

Blum, S., Olmstead, W., Bearden, R., Thermal Decomposition of Naphthenic Acids, USA Patent serial No. US5820750A, 1998

Cox, R. A., Acids and Bases, Solvent Effects on Acid–base Strength, by Brian G. Cox, Angewandte Chemie International Edition,Vol. 52, No. 30, p. 7638-7638, 2013.

Das, J., Parida, K.M., Heteropoly Acid Intercalated Zn/Al Htlc as Efficient Catalyst for Esterification of Acetic Acid Using N-Butanol, Journal  Molecular Catalysis A: Chemistry, Vol. 264, p. 248-254, 2007.

Derungs, W., Naphthenic Acid Corrosion—an Old Enemy of the Petroleum Industry, Corrosion, Vol. 12, No.12, p. 41-46, 1956.

Duncum, S, Osborne, CG., Process for Deacidifying A Crude Oil System, US Patent 6 464,859, 2002.

Fu, X., Dai, Z., Tian, S., Long, J., Hou, S., Wang, X., Catalytic Decarboxylation of Petroleum Acids from High Acid Crude Oils over Solid Acid Catalysts, Energy Fuel, Vol. 22, p. 1923–1929, 2008.

Huang, M., Zhao, S., Li, P., Huisingh, D., Removal of Naphthenic Acid by Microwave, Journal Cleaner Production, Vol. 14,   p. 736–739, 2006.

Khan, M., Riaz, A., Yi, M., Kim, J., Removal of Naphthenic Acids from High Acid Crude via Esterification with Methanol, Fuel Processing Technology,  Vol.165, p.123-130, 2017.

Li, X., Zhu, J., Liu, Q., Wu, B., The Removal of Naphthenic Acids from Dewaxed VGO via Esterification Catalyzed by Mg–Al Hydrotalcite, Fuel Processing Technology, Vol. 111, p. 68–77, 2013.

Mandal, PC, Sasaki, M., Total Acid Number Reduction of Naphthenic Acids Using Supercritical Fluid and Ionic Liquids, Recent Insights in Petroleum Science and Engineering, Book Chap. p. 251-271, 2018.

Martínez-Palou, R., Luque, R., Applications of Ionic Liquids in the Removal of Contaminants from Refinery Feedstocks: An Industrial Perspective, Energy Environmental Science, Vol. 7, p. 2414–2447, 2014.

Rana, BS, Cho, D-W., Cho, K., Kim, J-N., Total Acid Number (TAN) Reduction of High Acidic Crude Oil by Catalytic Esterification of Naphthenic Acids in Fixed-bed Continuous Flow Reactor, Fuel Vol. 231, p. 271–80, 2018.

Redondo, N.,  Dieuzeide, M.L., Amadeo, N., Acid Removal from Crude Oils by Catalytic Esterification Naphthenic Acid Catalize by Mg/Al Hydrotalcite, Catalysis Today,  Vol. 353, p. 82-87, 2020

Shah, S.N., Chellappan, L.K., Gonfa, G., Mutalib, M.I.A., Pilus, R.B.M., Bustam, M.A., Extraction of Naphthenic Acid from Highly Acidic Oil Sing Phenolate Based Ionic Liquids, Chemical Engineering Journal, Vol. 284, p. 487–493, 2016.

Silva, J.P., Costa, A.L.H., Chiaro, S.S.X., Delgado, B.E.P.C., De Figueiredo, M.A.G., Senna, L.F., Carboxylic Acid Removal from Model Petroleum Fractions by a Commercial Clay Adsorbent, Fuel Processing Technology, Vol. 112, p. 57–63, 2013.

Slavcheva, E., B. Shone, Turnbull, A., Review of Naphthenic Acid Corrosion in Oil Refining,  British Corrosion Journal , Vol. 34, No. 2, p. 125-131, 1999.

Trachte, K. L., Robbins, W. K., Process for Selectively Removing Lower Molecular Weight Naphthenic Acids from Acidic Crudes, Google Patents, 1999.

Wang, Y., Chu, Z., Qiu, B., Liu, C., Zhang, Y., Removal of Naphthenic Acids from a Vacuum Fraction Oil with an Ammonia Solution of Ethylene Glycol, Fuel, Vol. 85, p. 2489–2493, 2006. 

Wang, H., Liu, X., Wu, Y., Hou, C., Qiu, Y., Guo, K., Microwave-assisted Synthesis of Ethylene Glycol-intercalated Nial Ldhs and Their Application for Intracrystalline Catalytic Esterification with Naphthenic Acids in Crude Oil, Energy & Fuels, Vol. 31, No. 9, p. 9898-9904, 2017.

Yan-Zhen, W., Jin-Yun, L., Xue-Ying, S., Hong-Ling, D., Chun-Min, S., Miao-Miao, Z., Yan-Ping, L., Removal of Naphthenic Acids from Crude Oils by Fixed-bed Catalytic Esterification, Fuel, Vol. 116, p. 723-728, 2014.

Zhang, A., Ma, Q., Wang, K., Liu, X., Shuler, P., Tang, Y., Naphthenic Acid Removal from Crude Oil through Catalytic Decarboxylation on Magnesium Oxide, Applied Catalysis, A General, Vol. 303, p. 103–109, 2006.