The Isolation, Purification And Identification Of Vanadium Compounds From Tahe Atmospheric Residue

This study focused on the separation, purification and identification of metallic compounds from Tahe Atmospheric Residue (THAR) and its components, through improved solvent-extraction and column chromatography. To obtain a higher extraction yield of vanadium compounds, THAR asphaltene was pretreated with polar solvent before the separation and purification process. Metallic compounds were characterized by Ultraviolet-visible Spectrophotometry (UV-vis), Atomic Absorption Spectroscopy (AAS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS).Improved separation result shows that kieselguhr is the best adsorbent, compared with silicagel, alumina and pretreated kieselguhr. Extract yield of Vanadium in THAR and its nC7-maltene were ordinal 19.4% and 60.8%; Compared with extract successively by methanol and ethanol, vanadyl compounds extracted reach up to 96% using methanol and chloroform in order, as the same time, 92% of oil matters were extracted. It means that extraction by methanol and chloroform is not work for separating and concentrating the metallic complexes. Triple-column chromatography was used to purify furtherly metallic complexes in place of column chromatography originally. The vanadyl porphyrins of nC7- maltene of THAR are found to be chiefly ETIO homologues maximizing at C31-32, and secondly DPEP porphyrins, and simultaneously small amounts of RHODO-ETIO, Di-DPEP and RHODO-DPEP porphyrins.Vanadium in nC7-asphaltene is 78% of all vanadium in THAR, and most of vanadium compounds in asphaltene are not detected by UV-vis. It was worked obviously by pretreating nC7- asphaltene of Tahe Atmospheric Residue with polar solvent. Extraction yield of vanadium changed from 16.3% to 37.0% in nC7-asphaltene after pretreatment.Identified by FT-ICR-MS, first, three types of porphyrins (ETIO, DPEP and RHODO- ETIO) exist in methanol extract of nC7-asphaltene pretreated. But methanol extract of nC7-asphaltene unpretreated contains ETIO and DPEP series vanadyl porphyrins. Second, ETIO, DPEP and RHODO-ETIO vanadyl porphyrins were detected in ethanol extract before or after the pretreatment, but carbon number distribution of every type porphyrin made changes. Carbon number of ETIO-vanadyl porphyrins changed from 26-35 to 27-33, and carbon number of DPEP made from 27-34 to 27-35, and RHODO-ETIO moved from 29-34 to 28-33. Last, vanadyl porphyrins were not detected in pyridine/water extract of nC7-asphaltene of THAR by FT-ICR-MS.