Dehydrogenation of n-butane to butenes

Details Dehydrogenation of n-butane to butenes Dehydrogenation of n-butane to butenes

2000-06-22

2001-02-13

Wood, Elizabeth D. (Department: 1755)

Chemistry of hydrocarbon compounds

Unsaturated compound synthesis

By dehydrogenation

C585S654000, C585S656000, C585S657000, C585S658000

Reexamination Certificate

active

06187984

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a catalyst suitable for the dehydrogenation of n-butane to butenes that with chlorination is further suitable, when used in the conversion of n-butane, for the production of an increased amount of BTX (benzene-toluene-xylene) and greater selectivity to the production of isobutylenes than attained with the unchlorinated catalyst; a process for the preparation of catalyst suitable for the conversion of n-butane and the use of the catalyst in processes for the conversion of n-butane.
BACKGROUND OF THE INVENTION
It is known that n-butane can be converted to other hydrocarbons in the presence of variety of catalyst supports impregnated with a variety of metals. A catalyst composition prepared according to a process of this invention has been found to be suitable for use in the dehydrogenation of n-butane to butenes. It has also been found that upon chlorination of this catalyst its suitability for use in the production of BTX from n-butane is improved.
SUMMARY OF THE INVENTION
It is an object of this invention to at least partially dehydrogenate n-butane to butenes.
Another object of this invention is to provide an improved alumina-based catalyst that can be utilized in the dehydrogenation of n-butane to butenes.
A further object of this invention is to provide a method for making an alumina-based catalyst that can be utilized in the dehydrogenation of n-butane to butenes.
It is another object of this invention to provide a chlorinated alumina-based catalyst.
Another object of the invention is to utilize a chlorinated alumina-based catalyst in the production of BTX from n-butane.
Still another object of the invention is to provide a method for preparing a chlorinated alumina-based catalyst that can be utilized in the production of BTX from n-butane.
The invention is an alumina-based catalyst that is prepared by impregnation with tin, steam treatment, impregnation with platinum and calcination in air to provide a catalyst composition and a process in which a feedstock containing n-butane is passed in contact with this catalyst composition under conditions to produce butenes. The invention also includes a catalyst composition prepared by the chlorination of the catalyst produced as set out above and a process in which a feedstock containing n-butane is passed in contact with this catalyst composition under conditions to produce BTX.
Other objects and advantages of the invention will become apparent from the detailed description and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
The alumina used in making the inventive compositions can be any alumina which when contacted with a feedstock containing n-butane under suitable operating conditions is not detrimental to the conversion of n-butane to butenes. The alumina can be alpha-alumina, beta-alumina, gamma-alumina, eta-alumina, delta-alumina, or combinations of any two or more thereof. The presently preferred alumina is gamma-alumina having a surface area in the range of about 40 m
2
/g to about 300 m
2
/g, a total pore volume in the range of about 0.1 ml/g to about 1 ml/g. These aluminas are commercially available as extrudate pellets.
According to the present invention any tin-containing compound which when combined with alumina is effective in producing butenes from the conversion of n-butane can be employed. Examples of preferred compounds are organic tin compounds that can be dissolved in organic solvents, these include, but are not limited to, tributyl tin acetate, trimethyltin, tetra-n-propyltin, tributyl tin hydride, trimethyl tin hydroxide, tri-n-propyltin hydroxide, tri-n-propyltin acetate, and mixtures of two or more thereof. Tributyl tin acetate is most preferred.
The amount of tin incorporated or impregnated into the alumina should provide a concentration effective to assure predetermined butene conversion yields employing the catalyst composition in the selective dehydrogenation of feedstock that contains n-butane. Generally, the weight percent of tin present in the impregnated alumina is in a range of about 0.001 to about 10 weight percent of the impregnated alumina composition. The preferred concentration of tin in the impregnated zeolite is in the range of about 0.01 to about 5 weight percent and, more preferably, from about 0.1 to about 2 weight percent of the impregnated zeolite composition.
It is essential to this invention that the alumina impregnated with tin be treated in the presence of steam at an elevated temperature. In the preferred embodiment of the invention the alumina impregnated with tin is a tin-aluminate.
Generally, this steam treatment can be conducted at a pressure in a range from below atmospheric pressure to about 1000 pounds per square inch absolute (psia). More typically, however, the pressure range is from about atmospheric to about 100 psia. The temperature of this steam treatment is generally in the range of about 400° C. to about 1000° C. Preferably, this temperature range is from about 500° C. to about 850° C. and, most preferably, the temperature of this heat treatment is in a range of about 550° C. to about 750° C.
The steam treated tin-aluminate is then impregnated with a platinum compound. Generally, any platinum-containing compound can be employed in the process of this invention. Examples of suitable platinum compounds include, but are not limited to, chloroplatinic acid, platinic chloride, platinum bromide, platinum iodide, tetramine platinum chloride, tetramine platinum nitrate, tetramine platinum hydroxide, tetrachlorodiamine platinum and combinations of any two or more thereof. Chloroplatinic acid is preferred.
The impregnating solution is an aqueous solution to which can be added a small amount of acid to aid in stabilizing the impregnating solution. Presently, when chloroplatinic acid, the preferred platinum compound, is used, hydrochloric acid (HCl) is added to the impregnating solution in an amount up to about 2 weight percent of the total aqueous impregnating solution.
The amount of platinum incorporated or impregnated into the tin-containing composition should provide a concentration effective to assure predetermined butene conversion yields employing the catalyst composition in the selective dehydrogenation of feedstock that contains n-butane. Generally, the weight percent of platinum present in the impregnated alumina is in a range of about 0.001 to about 10 weight percent of the impregnated zeolite composition. The preferred concentration of platinum in the impregnated zeolite is in the range of about 0.01 to about 5 weight percent and, more preferably, from about 0.1 to about 2 weight percent of the impregnated zeolite composition.
The platinum-impregnated tin-containing catalyst composition is treated at an elevated temperature in the presence of an oxygen containing atmosphere, preferably air. Generally, this calcination can be conducted at a pressure in a range from below atmospheric pressure to about 1000 pounds per square inch absolute (psia). More typically, however, the pressure range is from about atmospheric to about 100 psia. The temperature of this heat treatment is generally in the range of about 400° C. to about 800° C. Preferably, this temperature range is from about 450° C. to about 700° C. and, most preferably, the temperature of this heat treatment is in a range of about 500° C. to about 600° C.
The chlorination of the calcined tin-aluminate containing platinum can be carried out by heating with a gas containing hydrogen an at least one chlorine-containing compound which can be HCl, a chloroalkane or mixture of these chlorination agents. Suitable chloroalkanes, which generally contain 1-4 carbon atoms per molecule and 1-6 chlorine atoms per molecule, can be, but are not limited to, chloromethane, dichloromethane, trichloromethane, carbon tetrachloride, chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethanes, tetrachloroethanes, hexachloroethanes, 1-chloropropane, 2-chloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, trichloropropanes, tetrachloropropanes

Affiliated with

Also associated with

Rating

Dehydrogenation of n-butane to butenes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dehydrogenation of n-butane to butenes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dehydrogenation of n-butane to butenes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2560197