Dehydration of water containing source of formaldehyde, and a method for producing an ethylenically unsaturated carboxylic ester
Disclosed are methods for dehydrating a water containing source of formaldehyde in which water is separated from the water containing source of formaldehyde using a zeolite membrane. In certain aspects, the water containing source of formaldehyde includes a separation enhancer having a relative static permittivity ranging from 2.5 to 20, and the water containing source of formaldehyde may further include methanol. In certain aspects, (meth)acrylic acid alkyl ester may be produced using the dehydrated source of formaldehyde.
1. A method for producing an ethylenically unsaturated carboxylic ester comprising:
contacting a dehydrated source of formaldehyde with a carboxylic acid ester in the presence of a catalyst,
wherein the dehydrated source of formaldehyde is obtained by
(i) providing a water containing source of formaldehyde, a separation enhancer in an amount of at least 10% by mass or more with respect to 100% by mass of the water containing source of formaldehyde, and methanol, the water containing source of formaldehyde having a water concentration ranging from 0.5 to 25% by mass of the water containing source of formaldehyde;
(ii) contacting the water containing source of formaldehyde, separation enhancer, and methanol with a zeolite membrane and
(iii) separating, by zeolite membrane pervaporation or zeolite membrane vapor permeation, at least 50% of the water from a majority of the water containing source of formaldehyde and from a majority of the separation enhancer to produce the said dehydrated source of formaldehyde, the dehydrated source of formaldehyde including the majority of the separation enhancer therein,
wherein the separation enhancer has a static permittivity of between 2.5 and 20 at 20° C. and atmospheric pressure,
wherein the separated water of step (iii) is a permeate and the dehydrated source of formaldehyde including the majority of the separation enhancer therein of step (iii) is a retentate; and
wherein the temperature of the water containing source of formaldehyde during separation is 0 to 200° C.
2. The method for producing an ethylenically unsaturated carboxylic acid ester according to claim 1 , wherein the ethylenically unsaturated acid ester is selected from the group consisting of methyl methacrylate and methyl acrylate.