Prediction of ultra low sulphur diesel catalyst performance using limited pilot plant data

Abstract

Due to the presence of refractory sulphur (S) compounds in the gasoil, the achievement of Ultra-low-Sulphur Diesel (ULSD) using the conventional bimetallic catalyst in the Hydrodesulphurization (HDS) process in order to bring sulphur down to less than 10 ppmwt is considered as a tough task/challenge and gain major attention due to the EPA regulations on the transportation fuel industry.In this work, a catalytic testing of four commercial alumina-supported cobalt–molybdenum (CoMo) catalysts were conducted using fixed bed pilot plant reactor using a complex real mixture of straight run gasoil fraction (C12-C20) in order to determine the operating conditions at industrial unit particularly by focusing on the refractory (S) compounds and determining their reaction kinetics parameters. A limited pilot plant real data and a simplified kinetic model were employed to estimate the kinetic parameters for the four tested CA, CB, CC and CD catalysts. A parameter estimation technique with explicit models was also used to determine their highest posterior density intervals. The technique is based on minimization of the sum of the square errors (SSE) between the experimental and predicted data of the residual sulphur concentrations in the product distributions. The results revealed that each catalyst showed, expectedly, different results translated into how longer a commercial run length can be extended.