Simultaneous Determination of Oil and Coke Contents in Spent Hydroprocessing Catalyst by Thermogravimetry

Abstract

Spent alumina-based nickel−molybdenum catalysts used for hydroconversion of heavy oil or residuum upgrading are subjected to thermogravimetric analysis (TGA) to determine oil and coke contents simultaneously. TGA or differential TGA curves clearly indicate that oil and carbonaceous materials are driven off at 100−300 °C and 300−700 °C ranges, respectively. The amounts of oil, coke, and inorganic residue obtained by the single-step TGA procedure are found to be in excellent agreement with those obtained by conventional methods such as Soxhlet extraction for the oil content followed by calcining of the deoiled catalyst in a muffle furnace for the coke and inorganic residue contents. Since the TGA results at heating rates of 10, 20, and 30 °C/min are found to be statistically invariant, the analysis time can be as short as 26 min, which is advantageous for monitoring and control of catalyst performance in an operating unit.