Investigation of metalloporphyrin compound in maltenes of duri crude oil

Abstract

Metalloporphyrin is one of the compounds that could potentially cause deactivation of catalysts in the process of catalytic cracking and hydrotreating. Knowledge of the structure of metalloporphyrin can be used as the basic information in overcoming the problem of catalyst poisoning. This work is performed to identify metalloporphyrins in the maltenes fraction of Duri crude oil. The low content of asphaltenes in Duri crude oil with a fractional weight of 0.79 %, allows a high level of metalloporphyrin in the fraction of maltenes which has a fractional weight of 82.73 %. Metalloporphyrin in the maltenes derivate fraction, saturates, aromatics, and resin were separated using column chromatography. Saturates, aromatics and resins have fractional weight of 49.75; 34.92; and 15.33 %, respectively. Only resin contained metalloporphyrin based on the analysis of UV-Vis spectrophotometer and Fourier-transform infrared spectroscopy (FT-IR), thus metalloporphyrins in resin was further separated into fractions by column chromatography. The result of UV-Vis spectrophotometer analysis for resin separation showed an absorbance peak of metalloporphyrin at 480–700 nm, while FT-IR analysis showed the presence of pyrrole group as porphyrin base framework with vibrational region at 400–1100 cm−1 The results of micro plasma-atomic emission spectrometer (MP-AES) analysis showed the presence of Fe, Ni, and V metals content. The liquid chromatography-mass spectrometer (LC-MS) analysis showed the molecular structure of the obtained compound was C33H34N4VO2. According to the results, metalloporphyrins presented in the maltenes fraction of Duri crude oil was vanadyl porphyrin.