Partial oxidation of propene for manufacture of acrolein, involves passing reaction mixture over catalyst bed having preset temperature zones whose transition is different from transition between preset fixed catalyst bed zones

摘要

A mixture of propene, molecular oxygen and inert gas, is passed over a fixed catalyst bed having temperature zones (A,B) maintained at 290-380 [deg] C. The fixed catalyst bed has two fixed catalyst bed zones having preset volume-specific activity. The transition from zone A to zone B in fixed catalyst bed do not coincide with transition from one fixed catalyst bed zone to another. The partial oxidation of propene in gaseous phase is performed in presence of heterogeneous catalyst. A reaction gas mixture comprising propene, molecular oxygen and at least one inert gas is passed over a fixed catalyst bed containing at least one multimetal oxide comprising molybdenum, iron and bismuth. The molar ratio of molecular oxygen and propene is = 1. The fixed catalyst bed is arranged in two spatially successive temperature zones (A,B), both maintained at 290-380 [deg] C. The fixed catalyst bed consists of at least two spatially successive fixed catalyst bed zones. The volume-specific activity within one fixed catalyst bed zone is substantially constant and increases sharply in the flow direction of the reaction gas mixture at the transition from one fixed catalyst bed zone to another fixed catalyst bed zone. The temperature zone (A) extends up to a conversion of propene of 40-80 mol%. On single pass of the starting reaction gas mixture through the entire fixed catalyst bed, the propene conversion is =90 mol% and the selectivity of acrolein formation based on converted propene is =90 mol %. The sequence in time in which the reaction gas mixture flows through the temperature zones (A,B) corresponds to the alphabetic sequence of the temperature zones. The hourly space velocity of the propene contained in the reaction gas mixture on the fixed catalyst bed is = 90 I(STP) of propene/I of fixed bed catalyst.h. The difference (TmaxA-TmaxB) between the highest temperature (TmaxA) of reaction gas mixture in zone A, and the highest temperature (TmaxB) of reaction gas mixture in zone B, is =0 [deg] C. The transition from temperature zone A to temperature zone B in the fixed catalyst bed do not coincide with a transition from one fixed catalyst bed zone to another fixed catalyst bed zone.