Patent DE-102005052923-A1 (DE)
Title: Stable continuous process for preparing acrolein and/or acrylic acid comprises dehydrogenating a propane to obtain a product gas mixture and introducing the mixture into a first separation zone to obtain another product gas mixture
Inventor: DIETERLE MARTIN
IPC: C07C5/333
Filed: 2005-11-03
Abstract: Stable continuous process for the preparation of acrolein and/or acrylic acid from propane comprises heterogeneously catalyzed dehydrogenation of a propane to obtain a product gas mixture A; optionally introducing the mixture A into a first separation zone to obtain product gas mixture A1; introducing mixture A or A1 into a zone B, where in an oxidation reactor, the propylene is oxidized with molecular oxygen to form e.g. acrolein and/or acrylic acid as end product and product gas mixture B; and determining the molecular oxygen content of the product gas mixture B. Stable continuous process for the preparation of acrolein and/or acrylic acid from propane comprises heterogeneously catalyzed dehydrogenation of a propane in the presence of a molecular oxygen to obtain a product gas mixture A containing propane and propylene, in a first reaction zone A; optionally introducing the product gas mixture A into a first separation zone, to separate a partial quantity or more of the components (which are contained in the mixture and different from propane and propylene) to obtain a remaining product gas mixture A1 containing propane and propylene; introducing product gas mixture A or A1 into a second reaction zone B for feeding at least an oxidation reactor, where in at least an oxidation reactor the propylene contained in the gas mixture A or A1 is subjected to a selectively heterogeneously catalyzed partial gas-phase oxidation with molecular oxygen to form acrolein and/or acrylic acid as end product, non-converted propane, excess molecular oxygen and optionally gas mixture B containing non-converted propylene; separating the end product and subsequently recycling the residue gas containing propane, molecular oxygen, non-converted propylene, at least partially non-converted propane, molecular oxygen and optionally non-converted propylene as molecular oxygen containing cycle gas 1 by cycle gas method, into the reaction zone A; continuously supplying fresh propane into at least one of the zones such as reaction zone A, separation zone A, reaction zone B and separating zone B, where the supply of the fresh propane takes place at a rate, which exhibits a stationary value in the stable operating condition of the process; and determining the molecular oxygen content of the product gas mixture B and comparing with the given stationary target content of the molecular oxygen in the product gas mixture B for stable operating condition of the process; where, if the content of the molecular oxygen at any point of time in the product gas mixture B is larger than the stationary target content, the supply rate of the fresh propane supplied at this time is larger than its stationary value and if the content of the molecular oxygen at any point of time in the product gas mixture B is smaller than the stationary target content, the supply rate of the fresh propane supplied at this time is smaller than its stationary value.