Patent Application
20050033102
The invention relates to catalyst systems useful in hydrocarbon upgrading processes and to methods for their use. In another aspect, this invention relates to processes for the disproportionation of a C5 paraffin.
It is known that ionic liquids can be used in various hydrocarbon conversion processes. However, we have found an ionic liquid dispersed on a support having an average pore diameter greater than about 225 angstroms is unexpectedly effective at disproportionating isopentane.
It is an object of this invention to provide an improved supported ionic liquid which when used in the disproportionation of a C5 paraffin results in increased product formation.
Another object of this invention is to provide an improved process for the disproportionation of a C5 paraffin in which the yield of disproportionation products is increased.
The inventive catalyst system comprises an ionic liquid dispersed on a support having an average pore diameter greater than about 225 angstroms. The inventive catalyst system can be used in the disproportionation of a C5 paraffin by contacting a C5 paraffin, under conversion conditions, with the inventive catalyst system.
Other objects and advantages of the invention will become apparent from the detailed description and the appended claims.
The hydrocarbon feed stream of the process of this invention can be any hydrocarbon-containing mixture that comprises at least one C5 paraffin such as n-pentane, 2-methylbutane, neopentane, or mixtures thereof, and an initiator selected from the group consisting of an olefin, alkyl halides, and combinations thereof. The olefin or alkyl halide preferably has in the range of from 2 to 20 carbon atoms per molecule, more preferably has in the range of from 3 to 6 carbon atoms per molecule, and most preferably has in the range of from 4 to 5 carbon atoms per molecule. Generally, the feed contains more than about 50 weight-percent C5 paraffin, preferably about 60-100 weight percent C5 paraffin, and more preferably about 75-90 weight percent C5 paraffin. The feed can contain other hydrocarbons that do not interfere with the process of this invention, i.e. minor amounts of other alkanes, such as n-butane, isobutane, n-hexane and the like, and alkenes (monoolefins).
The inventive catalyst system comprises, consists of, or consists essentially of an ionic liquid dispersed on a support having an average pore diameter greater than about 225 angstroms, preferably greater than about 250 angstroms, and more preferably greater than about 275 angstroms. The support preferably has a surface area less than about 700 m2 per gram and is preferably non-crystalline. The support is most preferably a silica.
The ionic liquid comprises, consists of, or consists essentially of a cation and an anion. The cation is preferably selected from the group consisting of ions defined by the formulas:
and combinations of any two or more thereof, wherein:
The anion is selected from the group consisting of halides of: Group IIIA metals, copper, zinc, iron, phosphorus and combinations thereof. More preferably, the anion is selected from the group consisting of chlorides of aluminum, gallium, copper, zinc, and iron; fluorides of phosphorus and boron, and combinations thereof.
The ionic liquid preferably has the general formula R1R2R3 NH+AlnCl3n+1−, wherein n=1, 2, or 3; and more preferably has the general formula (CH3)3NH+Al2 Cl7−.
The inventive process comprises, consists of, or consists essentially of, a) contacting, under conversion conditions, the hydrocarbon feed stream with the inventive catalyst system; and b) withdrawing a product stream comprising a C4 paraffin which is preferably isobutane and at least one C6 paraffin which is preferably a hexane isomer.
The conversion conditions include a temperature in the range of from about 100° F. to about 1000° F., preferably in the range of from about 140° F. to about 250° F., and more preferably in the range of from about 150° F. to about 220° F.
The following examples are presented to further illustrate this invention and are not to be construed as unduly limiting its scope.
For Inventive Run 1, 7.38 grams of AlCl3 were mixed with 2.71 grams of trimethylammonium chloride (N(CH3)3:HCl) (at approximately 2 equivalents AlCl3 and 1 equivalent (N(CH3)3:HCl)) to form an ionic liquid. A 1.98 gram quantity of silica spheres, having a surface area greater than about 400 m2/g, a pore volume of 3.0 cc/g, and an average pore diameter of 308 Å, were added to the ionic liquid along with 17.01 grams of the inert support Alundum alumina to form a mixture. The mixture was then charged to a reactor.
An isopentane feed was charged to the reactor at varying reactor temperatures and liquid hourly space velocities. Results of such are presented in Table 1.
The data in Table I demonstrate that a catalyst system including an ionic liquid dispersed on silica spheres having an average pore diameter greater than about 225 Å (specifically, 308 Å) results in significant isopentane conversion, with even higher conversions at reactor temperatures in excess of 150° F.
For Runs 2 through 5, the catalysts were made from about 2 equivalents AlCl3 and about 1 equivalent N(CH3)3:HCl to generate an ionic liquid to which silica supports were added, as shown in Table II. An isopentane feed comprising about 98.2-98.4 wt. % isopentane, about 0.8-1.4 wt. % C5; ˜0.2 wt. % neo C5=and about 0.13-0.15 wt. % C4 paraffins, was charged to each reactor at an LHSV of 2 hr. Results of the conversions are presented in Table II.
1A = Davison G-57 grade
2B = Silica microspheres from Philadelphia Quartz
The data in Table II demonstrate that ionic liquid catalyst systems which have silica supports with higher average pore diameters result in higher isopentane conversion as compared to ionic liquid catalyst systems which have lower average pore diameter silica supports.
For Inventive Run 6, 2.19 grams of N(CH3)3:HCl were added to 7.92 grams of GaCl3 to form an ionic liquid. A 2.05 gram quantity of silica spheres, having a surface area greater than about 400 m2/g, a pore volume of 3.0 cc/g, and an average pore diameter of 308 Å, were added to the ionic liquid along with 17.94 grams of Alundum alumina to form a mixture. The mixture was then charged to a reactor. An isopentane feed, as shown in Table III, was charged to the reactor. Results of such are presented in Table III.
