The present invention relates to a method of preparing butadiene. More particularly, the present invention relates to a method of preparing butadiene by feeding butene and oxygen into a reactor containing a composite metal oxide catalyst and performing oxidative dehydrogenation, wherein a mole ratio of the oxygen to the butene is 1.8 to 2.2. In accordance with the present invention, a method of preparing butadiene to secure long-term operation stability by maintaining the intensity of a catalyst despite oxidative dehydrogenation and not to decrease selectivity due to less side reaction is provided.

In the operation of an oxidative dehydrogenation (ODH) process, it is desirable to remove oxygen in the product stream for a number of reasons, including to reduce oxidation of the product. This may be achieved by having several pre-reactors upstream of the main reactor having a catalyst system containing labile oxygen. The feed passes through one or more reactors saturated with labile oxygen. When the labile oxygen is consumed through a valve system, the pre-reactor accepts product from the main reactor and complexes reactive oxygen in the product stream until the catalyst system is saturated with labile oxygen. Then the reactor becomes a pre-reactor and another pre-reactor becomes a scavenger.

A catalyst for producing butadiene using n-butene as a raw material, a process for producing the same and a process for producing butadiene using the catalyst are provided, and specifically, a catalyst for producing butadiene by gas-phase contact oxidative dehydrogenation of n-butene, which is capable of stably producing butadiene in a high yield from the beginning of the reaction, a process for producing the same and a process for producing butadiene, in which the catalyst is a shaped catalyst containing a complex metal oxide having molybdenum as an essential ingredient, wherein the pore volume of macropores is 80% or more, more preferably 90% or more, based on the total pore volume, are provided.

In the operation of an oxidative dehydrogenation (ODH) process, it is desirable to remove oxygen in the product stream for a number of reasons, including to reduce oxidation of the product. This may be achieved by having several pre-reactors upstream of the main reactor having a catalyst system containing labile oxygen. The feed passes through one or more reactors saturated with labile oxygen. When the labile oxygen is consumed through a valve system, the pre-reactor accepts product from the main reactor and complexes reactive oxygen in the product stream until the catalyst system is saturated with labile oxygen. Then the reactor becomes a pre-reactor and another pre-reactor becomes a scavenger.

The present invention relates to a catalyst for the dehydrogenation of hydrocarbons which is based on iron oxide and a process for producing it. The catalyst comprises at least one iron compound, at least one potassium compound and from 11 to 24% by weight of at least one cerium compound, calculated as CeO.sub.2, wherein the at least one iron compound and the at least one potassium compound are at least partly present in the form of one or more K/Fe mixed oxide phases of the general formula K.sub.xFe.sub.yO.sub.z, where x is from 1 to 17; y is from 1 to 22 and z is from 2 to 34, and comprises at least 50% by weight, based on the total catalyst, of the K/Fe mixed oxide phases, and also a process for producing it.

There is provided a process for producing a shaped catalyst for a fixed bed oxidation reaction or a fixed bed oxidative dehydrogenation reaction, the catalyst having both of sufficient mechanical strength and catalyst performance, and the catalyst is produced by supporting a catalyst powder containing a complex metal oxide having molybdenum as an essential ingredient on an inert support by a tumbling granulation method at a relative centrifugal force of 1 to 35 G.

In the operation of an oxidative dehydrogenation (ODH) process, it is desirable to remove oxygen in the product stream for a number of reasons, including to reduce oxidation of the product. This may be achieved by having several pre-reactors upstream of the main reactor having a catalyst system containing labile oxygen. The feed passes through one or more reactors saturated with labile oxygen. When the labile oxygen is consumed through a valve system, the pre-reactor accepts product from the main reactor and complexes reactive oxygen in the product stream until the catalyst system is saturated with labile oxygen. Then the reactor becomes a pre-reactor and another pre-reactor becomes a scavenger.