Research Of Performance On Acrylic Acid Catalyst

The acrylic acid(AA), CH₂=CH-COOH, is an important material for the production of acrylic esters(AE) , acrylic resins , acrylic rubbers and polyacrylates.The oxidation of propylene to acrylic acid in the gas phase is carried out in two connected stages in CNPC Lanzhou Petroleum and Chemical Company Plant ACRYLIC ACID PLANT. In the first stage , propylene is oxidized to an intermediary product acrolein. In the second stage , acrolein is oxidized further to acrylic acid .The following equations are valid for the desirable main reaction:CH₂=CH-CH₃+O₂→CH₂=CH-CHO+H₂O CH₂=CH-CHO+1/2O₂→CH₂=CH-COOHParallel here to, propylene, acrolein or acrylic acid are completely oxidized (over-oxidation/combustion) undesirably to carbon oxides (CO, CO₂). The process gas after the reaction zone of the first stage reactor is immediately cooled-down (cooling zone), to avoid undesirable by-reaction. The oxidation air is sucked in a compressor, mixed with recycle gas and steam and charged with the feedstock propylene. The feedstock propylene mixture enters the first stage reactor, where the partial oxidation to acrolein takes place. The intermediate product acrolein after cooling enters the second stage reactor and is oxidized to the end-product acrylic acid. By the test of acrylic acid catalyst provided by the NKC company of Japan in a pilot plant, we determinate mainly the process condition of the catalyst of the propylene oxidized to acrolein and acrolein oxidized to acrylic acid of activity,selectivity,the conversion of propylene,the conversion of acrolein,the yield of acrylic acid,reaction temperature,reaction press and so on. The following is optimum process condition:The reaction temperature of the first stage reactor : 320±10°C ; the conversion of propylene:≥98% ;the space velocity of propylene: 95hr^-1; the reaction temperature of the second stage reactor: 260±10°C; the conversion of acrolein :≥99.85% ;the space velocity of acrolein: 96.5hr^-1.We conclude that the catalyst of acrylic acid (YX-38,T-202) has a better range of the process condition ;the performance of the conversion of propylene,the conversion of acrolein and the yield of acrylic acid are better: to the first stage reactor : the conversion of propylene:≥98% ; the yield of the acrolein adding acrylic acid :92～93mol%; the yield of the carbon monoxide adding carbon dioxide:≤4mol%; to the second stage reactor: the conversion of acrolein :≥99.85% ; the conversion of acrolein :≥99.85% ;the yield of acrylic acid :≥88mol%; the yield of acrolein :≤1mol%.