Solid-liquid stirred reactors are commonly used in conversion of post processing gas to liquid hydrocarbons, Fischer-Tropsch synthesis and alcohols (such as methanol). Computational Fluid Dynamics (CFD) is being used to predict hydrodynamics and population balance models (PBM) for catalyst particles in scale-up stirrer reactor. Therefore, modelling of catalyst particles in paraffin oil interactions into elliptical bottom stirred tank could be helpful to practical application in methanol synthesis. In the present work CFD simulations have been carried out to study solid distribution in liquid oil in stirred tank using Lagrangian-Eulerian (LE) approach along with standard k-epsilon turbulence model. A stirrer movement has been modelled using multiple reference frame (MRF) approach. The effects of dispersed solid phase coupling with BM have been investigated for time depended case. As expected, particles coalescence and breakage mechanism increase with a stirrer speed. The prediction in terms of velocity profile of solid distributions has been in reasonable agreement with the literature experimental data. Effect of pressure and temperature also has a significant impact on the catalyst particles population balance. Moreover, CFD simulations are qualified as a promising tool for predicting hydrodynamics of catalyst particles population balance in scale-up process. (C) 2017 Elsevier B.V. All rights reserved.