The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a comprising n-butenes, B) feeding the input gas stream a comprising n-butenes and a gas containing at least oxygen into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, water vapor, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b by contacting with a cooling medium in at least one cooling zone, the cooling medium being at least partly recycled and having an aqueous phase and an organic phase of an organic solvent, wherein the organic solvent is selected from the group consisting of toluene, o-, m- and p-xylene, mesitylene, mono-, di- and triethylbenzene, mono-, di- and triisopropylbenzene and mixtures thereof, and the mass ratio of the aqueous phase to the organic phase in the cooling medium when it is fed into the cooling zones prior to the contacting with the product gas stream being from 0.015:1 to 10:1, Cb) compressing the cooled product gas stream b which may have been depleted of high-boiling secondary components in at least one compression stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; D) removing uncondensable and low-boiling gas constituents comprising oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases, as gas stream d2 from the gas stream c2 by absorbing the C.sub.4 hydrocarbons comprising butadiene and n-butenes in an absorbent, giving an absorbent stream laden with C.sub.4 hydrocarbons and the gas stream d2, and then desorbing the C.sub.4 hydrocarbons from the laden absorbent stream, giving a C.sub.4 product gas stream d1, E) separating the C.sub.4 product stream d1 by extractive distillation with a butadiene-selective solvent into a stream e1 comprising butadiene and the selective solvent and a stream e2 comprising n-butenes; F) distilling the stream e1 comprising butadiene and the selective solvent into a stream f1 consisting essentially of the selective solvent and a stream f2 comprising butadiene.

Oxidative dehydrogenation of light paraffins, such as ethane at moderate temperatures (<500 C.) to produce ethylene without the formation of side products such as acetic acid and/or other oxygenated hydrocarbons is achieved using tellurium-free, multimetallic catalysts possessing orthorhombic M1 phase and other crystalline structures that have an important role for obtaining high performance catalysts for the oxidative dehydrogenation of ethane to ethylene. Such catalysts are prepared using thermal and hydrothermal methods.

The present invention relates to a bismuth molybdate-based composite oxide catalyst having a microporous zeolite coating layer on the surface thereof and thus having high selectivity for 1,3-butadiene, a method of preparing the same, and a method of preparing 1,3-butadiene using the same. The catalyst has a microporous zeolite coating layer, and thus enables only gaseous products (light) to selectively pass through the zeolite coating layer, improving selectivity for 1,3-butadiene.

Provided are a catalyst that may suppress the production of a coke-like substance in a reaction for producing a conjugated diolefin from a mixed gas including a monoolefin having 4 or more carbon atoms and molecular oxygen. A composite metal oxide catalyst for producing a conjugated diolefin from a mixed gas including a monoolefin having 4 or more carbon atoms and molecular oxygen by a catalytic oxidative dehydrogenation reaction, the composite metal oxide catalyst having a relative intensity range of X-ray diffraction peaks represented by the following Formula (A): 0Rh(=Ph1/Ph2)<0.8 (A) wherein Ph1 represents the maximum peak height within the range of 2=28.10.2 for the X-ray diffraction peaks; Ph2 represents the maximum peak height within the range of 2=27.90.2 for the X-ray diffraction peaks; and Rh represents the relative intensity ratio of Ph1 with respect to Ph2.

A method for producing diene in which diene can be produced in a high yield by using a raw material including a branched olefin and a straight chain olefin is provided. The method for producing diene comprises: a step 1 of obtaining an internal olefin by removing a branched olefin from a raw material including at least the branched olefin and a straight chain olefin; a step 2 of isomerizing the internal olefin to a terminal olefin by using an isomerization catalyst; and a step 3 of producing diene from the terminal olefin obtained in the step 2 by oxidative dehydrogenation using a dehydrogenation catalyst.

A method for producing diene comprises a step 1 of obtaining a straight chain internal olefin by removing a branched olefin from a raw material including at least the branched olefin and a straight chain olefin; and a step 2 of producing diene from the internal olefin by oxidative dehydrogenation using a first catalyst and a second catalyst, and the first catalyst has a complex oxide including bismuth, molybdenum and oxygen, and the second catalyst includes at least one selected from the group consisting of silica and alumina.

Provided are a catalyst which, in a reaction. for producing a conjugated diolefin by catalytic oxidative dehydrogenation from a mixed gas including a monoolefin having 4 or more carbon atoms and molecular oxygen, may suppress the production of a coke-like substance and improve the long-term stability of the reaction; and a method for producing the same. Disclosed is a composite metal oxide catalyst for producing a conjugated diolefin by a gas phase catalytic oxidative dehydrogenation reaction from a mixed gas including a monoolefin having 4 or more carbon atoms and molecular oxygen, the composite metal oxide catalyst having a solid acidity of 35 to 172 mol/g.

A method for producing a conjugated diolefin is configured as follows. A monoolefin having four or more carbon atoms is fed from a monoolefin feed nozzle(s) installed at n place(s) (n=1, 2, . . . , n). In addition, at least 50% or more of a total amount of an oxygen-containing gas is fed from an oxygen-containing gas feed nozzle located at a bottom of a fluidized bed reactor. Furthermore, the monoolefin feed nozzles at distances a1, a2, . . . , an from the oxygen-containing gas feed nozzle feed the monoolefin having four or more carbon atoms at ratios of b1, b2, . . . , bn (b1+b2+ . . . +bn=1), respectively, and an arithmetic mean value represented by the following formula and obtained from the above distances and the above ratios is 100 mm or more.

arithmetic mean value=a1*b1+a2*b2+ . . . +an*bn

An ethylbenzene dehydrogenation catalyst, a preparation method therefor, and the use thereof are provided. The catalyst includes Fe.sub.2O.sub.3, K.sub.2O, CeO.sub.2, MoO.sub.3 and CaO. The exposed crystal face area of CeO.sub.2 (100) accounts for 60% or more of the total exposed crystal face area of CeO.sub.2. The catalyst is used in a reaction for preparing styrene by means of dehydrogenating ethylbenzene at a low water ratio, and has high activity and stability.

The present invention relates to a catalyst in which a ratio (B/A) of a cumulative pore volume (B) in a pore diameter of 0.35 m to 4.0 m to a cumulative pore volume (A) in a pore diameter of 4.0 m to 10.0 m measured by mercury porosimetry is 2.5 to 15.0, and a cumulative specific surface area is less than 5 m.sup.2/g.