Conversion of heavy hydrocarbon to aromatics and light olefins

Details Conversion of heavy hydrocarbon to aromatics and light olefins Conversion of heavy hydrocarbon to aromatics and light olefins

1998-05-13

2001-03-20

Griffin, Walter D. (Department: 1764)

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Reforming

C208S120010, C208S141000, C585S653000, C585S655000, C585S656000

Reexamination Certificate

active

06203694

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to the field of hydrocarbon upgrading processes. In another aspect, the invention relates to the conversion of heavy hydrocarbon streams to aromatics and ethylene, propylene and butylene.
Developments in zeolite catalysts useful in hydrocarbon conversion processes have led to the use of zeolite catalysts for the conversion of heavy hydrocarbon streams containing heavy olefins to aromatics without the addition of hydrogen. The conversion of C
2
-C
4
alkanes and alkenes to produce aromatics using zeolite catalysts was found to be an effective process by both Cattanach (U.S. Pat. Nos. 3,760,024 and 3,756,942) and Yan et al. (U.S. Pat. No. 3,845,150). Nemet-Marrodin et al. have added to the understanding of the conversion of heavy hydrocarbon streams containing heavy olefins to aromatics using zeolite catalysts by suggesting the use of a purified recycle stream in U.S. Pat. No. 5,186,908. Other patents representative of aromatization of heavy hydrocarbon streams containing heavy olefins using zeolite catalysts include Young, U.S. Pat. No. 4,356,338, which discloses reducing coke formation on zeolite catalysts by treating the catalyst with phosphorus and steam, and Tabak et al., U.S. Pat. No. 4,751,338, which discloses continuous catalyst regeneration and the recycle of C
5
+ aliphatics in a fluidized bed.
These processes are effective in preferentially converting heavy hydrocarbons to aromatics at the expense of light olefin yield. Also, there is limited flexibility in these processes to shift the conversion of heavy hydrocarbons from aromatics to light olefins. Therefore, development of a process for converting heavy hydrocarbons to aromatics and light olefins wherein the yield of light olefins is enhanced would be a significant contribution to the art and to the economy by allowing the flexibility to preferentially convert heavy hydrocarbons to either aromatics or light olefins depending on market conditions.
BRIEF SUMMARY OF THE INVENTION
It is, thus, an object of this invention to provide a process for converting heavy hydrocarbon streams to aromatics and ethylene, propylene and butylene.
A further object of this invention is to provide a method for increasing the conversion of heavy hydrocarbons to light olefins in a process for the conversion of heavy hydrocarbon streams to aromatics and light olefins.
In accordance with the present invention, a method has been found for increasing the conversion of heavy hydrocarbons to light olefins in a process for the conversion of heavy hydrocarbon streams to aromatics (BTX) and light olefins. The method includes the steps of:
(a) introducing a heavy hydrocarbon having at least 5 carbon atoms per molecule into a reaction zone containing a zeolite catalyst and operating the reaction zone under reaction conditions sufficient for converting the heavy hydrocarbon to light olefins and BTX;
(b) introducing a paraffin stream comprising pentane into the reaction zone as a co-feed with the heavy hydrocarbon;
(c) withdrawing from the reaction zone a reactor effluent comprising light olefins;
(d) identifying a percent conversion of the heavy hydrocarbon to light olefins when there is no introducing step (b); and
(e) controlling the rate of introduction of the paraffin of introducing step (b) such that the percent conversion of the heavy hydrocarbon to light olefins exceeds the percent conversion of identifying step (d).
Other objects and advantages will become apparent from the detailed description and the appended claims.


REFERENCES:
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patent: 3617486 (1971-11-01), Lewis et al.
patent: 3756942 (1973-09-01), Cattanach
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patent: 4356338 (1982-10-01), Young
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U.S. application No. 09/114,992, filed Jul. 14, 1998.
U.S. application No. 09/022,628, filed Feb. 12, 1998.
U.S. application No. 09/035,198, filed Mar. 5, 1998.

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