A study was undertaken to determine whether the performance of dry methane reforming could be affected by catalyst particle clusters in circulating fluidized bed reformers. Flow behavior and chemical reactions through a quiescent catalyst cluster were predicted. The distributions of gas temperature and concentrations of gas species were obtained using a simple two-dimensional model with Rh/Al2O3 catalyst particles. Numerical results show that the reforming reaction rate on catalyst particles in the cluster is much smaller than the rate on isolated catalyst particle in the stream. The molar ratio of H-2/CO is increased due to catalyst particle clustering. The effects of gas temperature, inlet gas velocity and reactor pressure on reforming reactions are also investigated. (c) 2007 Elsevier B.V. All rights reserved.