Hyperfine Interactions 57 (1990) 1919-1922 1919 A MOSSBAUER STUDY OF IRON-CONTAINING PHASES IN A VANADIUM OXIDE CATALYST FOR THE OXIDATION OF SULPHUR DIOXIDE IN SULPHURIC ACID PRODUCTION D. KLISSURSKI, L. MAKEDONSKI, I. MITOV * and V. BLUSKOV Institute of General and Inorganic Chemistry 9 Institute of Kinetics and Catalysis, Academy of Sciences of Bulgaria, B-1040 Sofia The iron-containing phases in fresh and partly deactivated vanadium oxide catalyst are identified by MOssbauer spectroscopy. As a result of exploitation of the catalyst the new phases of Fe304, FeSO 4 and Fe-2(SO4) 3 alongwith presence of o~-Fe-203 are formed. The M6ssbauer spectroscopy presents new possibilities for studying the composition chmages in iron-containing phases, and provides a tool to reveal the reasonsleading to deactivation of industrial vanadium catalysts. 1. Introduction The comparative study of fresh and waste catalysts for oxidation of sulphur dioxide in sulphuric acid production is of definite theoretical and practical interest. The present investigation aims at identifying iron-containing phases in the samples of fresh and partly deactivated vanadium oxide catalysts by MiSssbauer spectroscopy. 2. Experimental Fresh industrial catalyst G-GDR was used. Waste, partly deactivated catalyst samples were taken along the contact apparatus height. The catalyst contains mainly the following phases: Fresh catalyst: SiOz-60.2%; SO3-21.7%; V205-5.5%; K20-6.6%. Waste catalyst, I layer: SIO2-59.9%; SO3-27.0%; VZO5-4.6%; K20-4.9%. The MiSssbauer spectra were recorded with a constant acceleration spectrome- ter at room temperature using 57Co radiation source in a Cr matrix, a-Fe was used for calibration and centre of the sextet was a reference point for the isomer shift calculation. The content of iron-containing components was determined by atomic absorp- tion spectroscopy, AAS, with a SP 192 Pye Unicam spectrometer. The iron content in fresh catalyst samples and waste catalyst are shown in table 1. 9 J.C. Baltzer A.G. Scientific Publishing Company