Patent ID: 8987521
Filing Date: 2015-03-24
Classification: B01J,C07C,Y02P

Abstract:
1. A method for preparing polyoxymethylene dimethyl ethers by acetalation reaction of formaldehyde and methanol comprising: A, in a formaldehyde polymerization reaction-rectification zone including a reaction-rectification device and a gas condenser, carrying out a continuous polymerization reaction by using an acidic ionic liquid IL I as a catalyst and an aqueous formaldehyde solution as a starting material, and passing the polymerization product through the rectification device and the gas condenser; B, in an acetalation reaction zone, in a single-stage or multi-stage stirred tank reactor, performing a continuous acetalation reaction between the condensate from the gas condenser in A and methanol by using an acidic ionic liquid IL II as a catalyst; C, in a separation zone including a single-stage or multi-stage rectification tower, a film evaporator and a phase separator connected in series, allowing the reactor effluent from the above acetalation reaction zone to drop in pressure, and flow into the rectification tower to be evaporated and condensed so as to be separated into two streams, one of a gaseous light component a1 and one of a liquid recycling catalyst; directing the recycling catalyst back to the acetalation reactor; allowing the light component a1 to flow into the film evaporator to be separated into a gaseous light component b1 comprising DMM