Polyoxymethylene dimethyl ethers as the additive of diesel oil can increase cetane number(CN) and improve fuel efficiency.It will have a broad application prospect as methanol downstream product.In a continuous flow fixed bed tubular reactor

using modified macroporous cation exchange resin as catalyst

the effects of temperature

formaldehyde/methanol molar ratio

pressure and liquid space velocity on the reaction were investigated.The single-factor and orthogonal experimental methods were applied at a broad experiment range(temperature 40—100℃

liquid space velocity 1.32—16.67 h-1

formaldehyde/methanol molar ratio 1—4 and pressure 0.1—3.0 MPa).The orthogonal experiment design was used to investigate the integral effect of these factors on the reaction.Thus the appropriate operating conditions were obtained.At temperature 70℃

formaldehyde/methanol molar ratio 3:1

liquid space velocity 1.32 h-1

pressure 2.0 MPa

conversion of methanol and selectivity of DMM3—8 were 69.72% and 62.08% respectively.