Zeolitic imidazolate framework-8(ZIF-8),which is a family of metal organic frameworks,is a new porous material with high porosity and large surface area,and it consists of zinc ions and 2-methylimidazole(2-MeIM)linkers.ZIF-8 shows unique adsorption behavior induced by structural transition which is reorientation of 2-MeIM linkers(gate adsorption).To utilize this unique adsorption property for various applications such as gas storage,separation and sensor,the control of the gate adsorption is of crucial importance.An interesting approach is the particle size dependence of the gate adsorption1.However,precise size control is difficult with batch type synthesis because the concentration and temperature distribution in a reactor is unavoidable.A microreactor is thus a first possibility to overcome this difficulty.