Abstract: The kinetics of oxidation of methanol to formaldehyde over Mo-Ce/SiO₂ catalyst might be described by the equation of Redox mechanism with adsorption of methanol and.formaldehyde. When the particle size of catalyst reached 3 mm in diameter, intraparticle diffusion affected the reaction rate strongly. The effectiveness factors of catalyst were determined by experiments and interpreted by the approximation method of general rate equation.The pressure of methanol in catalyst pore might be obtained by equation .

Key words: Oxidation of methanol to formaldehyde, Effectiveness factor, Pressure profile of methanol