Concentration of aqueous acrylic acid

Claim 1

PROCESS FOR THE CONCENTRATION OF AQUEOUS ACRYLIC ACID, COMPRISING DISSOLVING THE AQUEOUS ACRYLIC ACID IN A LOWER ALIPHATIC KETONE, ADDING TO THE SOLUTION THUS OBTAINED A SALT SELECTED FROM THE GROUP OF NICKEL CHLORIDE, NICKEL BROMIDE, AND A MIXTURE THEREOF, SHAKING SAID SOLUTION WITH THE ADDED NICKEL SALT AT A TEMPERATURE OF 40* TO 70*C., SAID SALT BEING USED IN AN AMOUNT NECESSARY TO FORM, AT THE TEMPERATURE EMPLOYED, WITH AT LEAST 80% OF THE WATER PRESENT IN THE AQUEOUS ACRYLIC ACID A SATURATED SOLUTION, THE KETONE BEING USED IN AT LEAST SUCH AN AMOUNT AS IS REQUIRED FOR THE AMOUNT OF WATER PRESENT IN ADDITION TO THE AMOUNT OF WATER MAKING UP THE NICKEL SALT SOLUTION TO BE DISTILLED OFF AZEOTROPICALLY, THUS CAUSING BY THE ADDITION OF SAID METAL SALT AND KETONE TWO LAYERS TO FORM, A HIGHLY CONCENTRATED AQUEOUS METAL SOLUTION, SUBSTANTIALLY FREE OF ACRYLIC ACID, FORMING THE LOWER LAYER OF SAID TWO LAYERS, A SOLUTION OF ACRYLIC ACID, WATER AND THE KETONE FORMING THE UPPER LAYER, THE AMOUNT OF WATER IN THE UPPER LAYER NOT EXCEEDING THE WATER CONTENT OF THE AZEOTROPIC MIXTURE OF WATER AND THE KETONE AT ATMOSPHERIC PRESSURE, SEPARATING THE LAYERS, AND FRACTIONATING THE UPPER LAYER TO FIRST REMOVE THE WATER-KETONE-AZEOTROPE AND THEN THE CONCENTRATED ACRYLIC ACID.