To design the two-stage catalytic oxychlorination process which is composed of two reactors utilizing a circulating fluidized bed with a pneumatic valve, it is necessary to control the circulation rate of the catalyst particles and to estimate the gas leakage between two reactors. For this process, a J-shaped pneumatic valve consisting of a downcomer, a horizontal pipe, a riser and two aeration gas inlets was utilized. In this study, the effects of the superficial gas velocities in the downcomer, the horizontal pipe and the riser and the pressure drop in the J-valve on both the mass flux of the solid particle and the gas entrainment with the particles were investigated. The opening or shutting down of the solid particle flow through the J-valve was performed by the control of the superficial gas velocity in the riser. When the valve is open, the mass flux of solid was controlled either by the superficial gas velocity in the downcomer at a constant pressure drop in the downcomer or by the pressure drop in the downcomer at a constant superficial gas velocity. The mass flux of solid was estimated well by a theoretical equation. The gas entrainment throughout a J-valve decreased with decreasing the downward gas velocity in the downcomer, whereas the gas entrainment occurred by not only the downward gas flow in the downcomer but also entrapment in the void in particles.