CATALYTIC CONVERSION OF LACTIC ACID INTO ACRYLIC ACID Russian patent published in 2016 - IPC B01J27/18 B01J27/25 B01J35/10 C07C51/377 C07C57/65 C07C57/55 

FIELD: chemistry.

SUBSTANCE: in this application described is catalytic dehydration of lactic acid into acrylic acid, characterised by high conversion of lactic acid, high selectivity of producing acrylic acid, high output of acrylic acid and low selectivity of producing and molar outputs of undesirable by-products. Mixed phosphate catalyst for conversion of lactic acid into acrylic acid contains at least two different phosphate salts selected from a group consisting of formulae (I), (II), (III) and (IV): ZH₂PO₄ (I); X_2-aHPO₄ (II); X₃(PO₄)_2-b (III); X_2+cP₂O₇ (IV), where Z is a metal group I, and where in each of formulae (II)-(IV) each X independently represents metal group I or II group, with the following conditions: in formula (II), if X is a metal group I, and means 0, and if X is a group II metal, then a denotes 1; in formula (III), if X is a metal group I, b denotes 1, and if X is a group II metal, b denotes 0; and, in the formula (IV), if X is a metal group I, then c means 2, and if X is a group II metal, then c means 0, and additionally said, at least two different phosphate salts contain two metals present in molar ratio relative to each other from 1:9 to 9:1. Also disclosed is a mixed phosphate catalyst containing at least two different phosphate salts, wherein one phosphate salt is a product of deposition of phosphoric acid (H₃RO₄) and nitrate salt of formula (V): X(NO₃)_2-b (V), and the other phosphate salt is selected from the phosphate salt of formula (II): X_2-aHPO₄ (II), where in each of formulae (II) and (V) X independently represents metal group I or II group under certain conditions.

EFFECT: disclosed is a method of producing acrylic acid by gas-phase catalytic dehydration of lactic acid, the method involves a step on which is brought into contact gaseous mixture containing lactic acid and water, with mixed phosphate catalyst.

17 cl, 1 dwg, 4 tbl, 8 ex