ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of sulfur in petroleum coke by ion chromatography after pyrohydrolysis sample preparation and Box–Behnken design optimization

Renan G. Marim, Amauri P. A. Rosa, Tatiane A. Maranhão, and Eduardo S. Chaves

Departamento de Química, Campus Trindade, Universidade Federal de Santa Catarina, Florianópolis, Brazil

E-mail: marimrenan@gmail.com

Received: 9 June 2023  Accepted: 15 November 2023

Abstract:

An easy method for the determination of sulfur (S) in petroleum coke by ion chromatography (IC) using a simple and low-cost lab-made pyrohydrolysis approach for sample preparation was proposed. Moreover, a multivariate optimization of the pyrohydrolysis using a Box–Behnken experimental design was performed. The optimized conditions were found using 100 mg of sample, 1000 °C of pyrohydrolysis temperature, and 22 min of reaction time, with an air and water flow rate of 0.2 L min⁻¹ and 0.1 mL min⁻¹, respectively. After pyrohydrolysis, the S was absorbed in a solution composed of 3.2 mmol L⁻¹ Na₂CO₃ + 1.0 mmol L⁻¹ NaHCO₃ + 250 mmol L⁻¹ H₂O₂. The accuracy of the proposed method was confirmed by analysis of certified reference material (CRM) and by the comparison of the results with those obtained via CS molecule by HR-CS GF MAS. The results showed a good agreement (92–103%) with the CRM values, and the linear regression analysis showed a good correlation between the S concentration found by the proposed method using IC and those by HR-CS MAS (R² of 0.96). The precision, evaluated by the relative standard deviation (RSD < 10%, n = 3), and the detection limit (0.8 mg kg⁻¹) were suitable for S determination in petroleum coke. The concentration of S in the analyzed samples ranged from 0.53 to 0.79%. Thus, the proposed study offers a simple, reliable, and attractive method for determining S in petroleum coke samples using IC and pyrohydrolysis as sample preparation.

Graphical abstract

Keywords: Sample preparation; Petroleum coke; Pyrohydrolysis; Multivariate optimization

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03218-z

Chemical Papers 78 (3) 1947–1957 (2024)