Deep selective hydrogenation process

Details Deep selective hydrogenation process Deep selective hydrogenation process

1999-10-08

2001-10-02

Griffin, Walter D. (Department: 1764)

Chemistry of hydrocarbon compounds

Adding hydrogen to unsaturated bond of hydrocarbon, i.e.,...

Hydrocarbon is contaminant in desired hydrocarbon

C585S809000, C585S844000, C585S845000, C585S846000

Reexamination Certificate

active

06297414

ABSTRACT:

The present invention relates to a process for the recovery of olefins from cracked gases employing a chemical absorption process. More particularly, the present invention relates to a process for improving the hydrogenation of acetylenes and dienes in the front end of an olefin recovery process.
BACKGROUND OF THE INVENTION
The processes for converting hydrocarbons at high temperatures, such as for example, steam-cracking, catalytic cracking or deep catalytic cracking to produce relatively high yields of unsaturated hydrocarbons, such as, for example, ethylene, propylene, and the butenes, are well known in the art. See, for example, Hallee et al., U.S. Pat. No. 3,407,789; Woebcke, U.S. Pat. No. 3,820,955, DiNicolantonio, U.S. Pat. No. 4,499,055; Gartside et al., U.S. Pat. No. 4,814,067; Cormier, Jr. et al., U.S. Pat. No. 4,828,679; Rabo et al., U.S. Pat. No. 3,647,682; Rosinski et al., U.S. Pat. No. 3,758,403; Li et al., U.S. Pat. No. 4,980,053; and Yongqing et al., U.S. Pat. No. 5,326,465.
It is also well known in the art that these mono-olefinic compounds are extremely useful in the formation of a wide variety of petrochemicals. For example, these compounds can be used in the formation of polyethylene, polypropylenes, polyisobutylene and other polymers, alcohols, vinyl chloride monomer, acrylonitrile, methyl tertiary butyl ether and other petrochemicals, and a variety of rubbers such as butyl rubber.
Besides the mono-olefins contained in the cracked gases, the gases typically contain a large amount of other components such as diolefins, hydrogen, carbon monoxide and paraffins. It is highly desirable to separate the mono-olefins into relatively high purity streams of the individual mono-olefinic components in order to facilitate downstream processing. To this end a number of processes have been developed to make the necessary separations to achieve the high purity mono-olefinic components.
An especially significant process for recovering olefins from cracked gases is a selective chemical absorption process described in Barchas et al., U.S. Pat. No. 5,859,304. In the Barchas et al. '304 patent, there is suggested the desirability for removing at least substantially all acetylenes and dienes from the depropanized cracked gas prior to the chemical absorption of the olefins. Removal of these acetylene and diene contaminants is beneficial because the acetylene and methyl acetylene will react with the absorbent solution to form potentially hazardous acetylides, and propadiene will be absorbed along with the olefins by the chemical absorbent thereby eventually contaminating the propylene product.
In Barchas et al. '304, a “deep” front end selective hydrogenation process is taught to effectuate the removal of at least substantially all of the acetylenes and dienes from the depropanized cracked gas prior to demethanization. The deep front end selective hydrogenation process disclosed in Barchas et al. '304 operates in the vapor phase and uses multiple catalysts beds, typically three with cooling between the beds. However, due to the severe conditions required in the last bed to hydrogenate the last traces of propadiene, it has been found that the process concomitantly hydrogenates some of the ethylene into ethane, typically around about 3%. The hydrogenation of ethylene into ethane increases the ethane recycle to the cracking furnaces, which results in increased feedstock consumption, larger equipment and increased processing costs. There is also a potential for the olefins to react uncontrollably with the large excess of hydrogen present in the cracked gas (a so-called runaway reaction). Additionally, the deep hydrogenation process of Barchas et al. '304 also has the disadvantage of running at relatively low space velocities (i.e., high gas residence times corresponding to larger catalyst volumes) in order to achieve the deep hydrogenation required.
Therefore, although the Barchas et al. '304 process has proved very beneficial to the art of recovering olefins from cracked gases, it would be highly desirable to provide an improved deep selective hydrogenation process which overcomes the aforementioned drawbacks.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved process for the recovery of olefins from a cracked gas stream which is sufficient to produce the olefins at high purity levels, i.e., polymer grade.
It is a further object of the present invention to provide an improved hydrogenation process which can be employed with a chemical absorption process for recovering olefins from cracked gases.
It is another object of the present invention to provide a hydrogenation process with reduced feed consumption, smaller equipment, lower processing costs, reduced potential for runaway reactions, and/or lower catalyst cost.
To this end, the present invention provides an improved process for hydrogenating the acetylenes and dienes in a cracked gas stream by employing an upstream less severe initial partial hydrogenation process, followed by bulk removal of hydrogen, and a downstream polishing/scavenging process to hydrogenate the residual acetylenes and dienes and scavenge the residual hydrogen.


REFERENCES:
patent: 1875924 (1932-09-01), Horsley
patent: 2077041 (1937-04-01), Davis et al.
patent: 2363309 (1944-11-01), Friedman et al.
patent: 2377221 (1945-05-01), Francis et al.
patent: 2391404 (1945-12-01), Friedman et al.
patent: 2471550 (1949-05-01), Shaw
patent: 2515140 (1950-07-01), Strand
patent: 2913505 (1959-11-01), Van Raay et al.
patent: 3101381 (1963-08-01), Baxter
patent: 3189658 (1965-06-01), Quinn
patent: 3395192 (1968-07-01), Long
patent: 3676516 (1972-07-01), Haskell et al.
patent: 3679763 (1972-07-01), Livingston
patent: 3756036 (1973-09-01), Ezell
patent: 3758603 (1973-09-01), Steigelmann et al.
patent: 3758605 (1973-09-01), Hughes et al.
patent: 3763200 (1973-10-01), Dines
patent: 3770842 (1973-11-01), Steigelmann et al.
patent: 3773844 (1973-11-01), Perry et al.
patent: 3787514 (1974-01-01), Bernusset
patent: 3864418 (1975-02-01), Hughes et al.
patent: 3865890 (1975-02-01), Steigelmann et al.
patent: 3944628 (1976-03-01), Suzuki et al.
patent: 4014665 (1977-03-01), Steigelmann
patent: 4025574 (1977-05-01), Tabler et al.
patent: 4060566 (1977-11-01), Yahnke
patent: 4105588 (1978-08-01), Balducci et al.
patent: 4121917 (1978-10-01), Baker et al.
patent: 4132744 (1979-01-01), Knifton
patent: 4154770 (1979-05-01), Kaplan
patent: 4174353 (1979-11-01), Marcinkowsky et al.
patent: 4235983 (1980-11-01), Steigelmann et al.
patent: 4328382 (1982-05-01), Alter et al.
patent: 4347392 (1982-08-01), Cosyns et al.
patent: 4398052 (1983-08-01), Tabler et al.
patent: 4409410 (1983-10-01), Cosyns et al.
patent: 4484015 (1984-11-01), Johnson et al.
patent: 4525180 (1985-06-01), Hirai et al.
patent: 4546094 (1985-10-01), Hirai et al.
patent: 4571442 (1986-02-01), Cosyns et al.
patent: 4652280 (1987-03-01), Boeren et al.
patent: 4747855 (1988-05-01), Hirai et al.
patent: 4762956 (1988-08-01), Liu et al.
patent: 4826603 (1989-05-01), Hayes, Jr. et al.
patent: 4864071 (1989-09-01), Hirai et al.
patent: 4943673 (1990-07-01), Norman et al.
patent: 5015268 (1991-05-01), Ho
patent: 5057641 (1991-10-01), Valus et al.
patent: 5059732 (1991-10-01), Cosyns et al.
patent: 5062866 (1991-11-01), Ho
patent: 5090977 (1992-02-01), Strack et al.
patent: 5191151 (1993-03-01), Eriksen et al.
patent: 5191153 (1993-03-01), Cymbaluk et al.
patent: 5202521 (1993-04-01), Brown et al.
patent: 5326929 (1994-07-01), Mehra et al.
patent: 5365011 (1994-11-01), Ramachandran et al.
patent: 5452581 (1995-09-01), Dinh et al.
patent: 5510550 (1996-04-01), Cheung et al.
patent: 5516851 (1996-05-01), Flick et al.
patent: 5516966 (1996-05-01), Nowack et al.
patent: 5523512 (1996-06-01), Cymbaluk et al.
patent: 5859304 (1999-01-01), Barchas et al.
patent: 9404477 (1994-03-01), None

Affiliated with

Also associated with

Rating

Deep selective hydrogenation process does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Deep selective hydrogenation process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Deep selective hydrogenation process will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2562682