Catalyst for catalytic pyrolysis process for the production...

Details Catalyst for catalytic pyrolysis process for the production... Catalyst for catalytic pyrolysis process for the production...

1998-10-15

2001-04-03

Dunn, Tom (Department: 1754)

Catalyst, solid sorbent, or support therefor: product or process

Zeolite or clay, including gallium analogs

And additional al or si containing component

C502S064000, C502S066000, C502S068000, C502S071000, C502S079000

Reexamination Certificate

active

06211104

ABSTRACT:

FIELD OF THE INVENTION
This present invention relates to a petroleum hydrocarbon catalytic pyrolysis catalyst for producing light olefins, and the process for preparing the same, and more particularly to a petroleum hydrocarbon catalytic pyrolysis catalyst for producing mainly ethylene, propylene, and also butylene as by-products.
BACKGROUND OF THE INVENTION
The traditional method for the production of ethylene from petroleum hydrocarbon is by steam thermal cracking in tubular furnace. The feeds adopted in steam thermal cracking are ethane, propane, butane, naphtha or atmospheric gas oil (AGO). The method using heavier hydrocarbon thermal cracking on solid heat carrier for producing ethylene also exists. The heat carriers generally adopted are inert solid particles such as quartz sand, coke, coke carbon, etc.
Quite a few literatures reported the methods relating the production of light olefins by petroleum hydrocarbon cracking or pyrolysis conversion with catalysts. U.S. Pat. No. 3,541,179, U.S. Pat. No. 3,647,682, DD 225,135 and SU 1,214,726 adopt the oxides supported metal catalysts, wherein the support can be SiO
2
.Al
2
O
3
or other oxides and the metal components are selected from elements of II
B
, V
B
, VII
B
and VIII
B
groups. As the supported metal possesses dehydrogenation property, it also accelerates the condensation and coking reaction during the reaction process of cracking. Hence, this type of catalysts can only be used for processing light feed stocks (<220° C.). Some patents adopt the composite oxides as catalysts, for example, U.S. Pat. No. 3,725,495 and U.S. Pat. No. 3,839,485 reported the catalysts comprising mainly ZrO
2
and/or HfO
2
, and also Al
2
O
3
, Cr
2
O
3
, MnO
2
and/or Fe
2
O
3
and alkali and alkaline metal oxides. Although alkali and alkaline earth metal oxide catalysts can promote the yield of ethylene, quite a lot of CO and CO
2
will be formed simultaneously.
In the field of the production of light olefins by petroleum hydrocarbon cracking with solid acid catalyst, DD 152,356A adopts the amorphous SiO
2
.Al
2
O
3
catalyst for cracking various liquid hydrocarbon and hydrocarbon fractions including gasoline, kerosene, gas oil or vacuum distillates, at 600~800° C. to produce light olefins with a C
2
=
~C
4
=
olefin yield of 40~50 wt % based on the feed. JP 60-224,428 disclosed a cracking catalyst using HZSM-5 as active component and alumina as matrix, for catalytic cracking a feed stock of C
5
~C
25
paraffinic hydrocarbons at 600~750° C. to obtain a C
2
=
~C
4
=
olefin yield of roughly 30 wt %. U.S. Pat. No. 3,758,403 revealed that a catalyst comprising both ZSM-5 zeolites and a large pore zeolite (e.g. X type or Y type) as active components in a ratio of 1:10~3:1 displayed a performance of raising gasoline octane number while increasing C
3
=
~C
4
=
olefin yield to about 10 wt %. In CN1069016A, a catalyst comprising 30~90 wt % SiO
2
, 20~70 wt % Al
2
O
3
, 0.5~30 wt % alkali and alkaline earth metal oxides and 1~30 wt % faujasite can produce 17~27 wt % yield of C
2
=
, 30~40 wt % yield of C
2
=
~C
4
=
at 650~900° C. with the heavy hydrocarbon as feedstock. In U.S. Pat. No. 4,980,053, a catalyst comprising HZSM-5 as active component supported on kaolin matrix obtained 40 wt % yield of C
3
=
+C
4
=
by cracking the heavy hydrocarbon feed at 500~650° C., but the yield of C
2
=
was low. In CN1083092A, an acidic molecular sieve catalyst containing crosslinking pillared interlayedrectorite molecular sieve and/or rare earth pentasil high silica zeolite is used for cracking heavy hydrocarbons at 680-780 and obtains a yield of 23 wt C
2
and 50 wt/C
2
-C
4
, U.S. Pat. No. 5,380,690 and ZL CN93102783.7 revealed a catalyst using a Y type zeolite and a phosphorus and rare earth containing high silica zeolite having a structure of pentasil as active components, and this catalyst with heavy oil fractions as feed stock can increase at 500~600° C. the gasoline octane number as well as the yield of C
2
=
~C
4
=
, mainly the yield of C
3
=
and C
4
=
.
The object of the present invention is to provide a novel zeolite-containing catalyst, said catalyst can attain the same level of yield of light olefins as that of steam thermal cracking at a lower reaction temperature than that of steam thermal cracking.
Another object of the present invention is to provide a method for preparing the said catalyst.
The further objects including the application of the said catalyst can be all learned from the content of the specification of the present invention including the examples.
The present invention provides a catalyst comprising a phosphorus—aluminum, phosphorus—magnesium or phosphorus—calcium containing high silica zeolite having the structure of pentasil prepared The phosphorus existing in the zeolite enables the zeolite to have higher hydrothermal activity-stability; aluminum or magnesium or calcium existing in the zeolite can adjust the acidity of the zeolite, which is favorable to the formation of C
2
=
. During the catalytic pyrolysis process in the presence of an acidic catalyst, hydrocarbon cracking reaction is carried out based on the carbonium ion reaction mechanism, hence the light olefins produced are mainly C
3
=
and C
4
=
. C
2
=
is commonly formed by free radical reaction mechanism in thermal cracking hydrocarbons, therefore acidic catalyst is unfavorable for the formation of C
2
=
. The acidity of the zeolite of the present invention is appropriately adjusted, thus the catalyst of the invention not only decreases the activation energy of the hydrocarbon cracking reaction, and consequently the reaction can proceed at a lower temperature than tat of steam thermal cracking, but also increases the yield of C
2
=
.
The present invention provides a catalyst comprising 10~70 wt % (based on the weight of the catalyst) of clay, 5~85 wt % of inorganic oxides, and 1~50 wt % of zeolite, said zeolite is a of 0~25 wt % of Y type zeolite and 75~100 wt % phosphorus—aluminum, phosphorus—magnesium or phosphorus—calcium containing high silica zeolite having a structure of pentasil.
Said clay in the catalyst of the invention can be all kind of clays usually used as a carrier for cracking catalyst, either natural or synthesized such as kaolin and kaolin polyhydrate, and may optionally be subjected to various chemical and/or physical treatment.
Said inorganic oxides in the catalyst of the invention are selected from amorphous SiO
2
.Al
2
O
3
, Al
2
O
3
and/or SiO
2
.
Said Y type zeolite in the catalyst of the invention may be a rare earth metal ion exchanged Y (REY) zeolite with a content of rare earth not less than 14 wt % (calculated as RE
2
O
3
), and may also be a stabilized high silica Y type zeolite with a higher silica/alumina mole ratio prepared by various chemical and/or physical method, such as hydrothermal method, acid treatment, framework silicon enriching method, or SiCl
4
treatment method.
Said phosphorus and aluminum or phosphorus and magnesium or phosphorus and calcium containing high silica zeolite having a structure of pentasil in the catalyst of the invention is a kind of high silica zeolite containing 2-8 wt % (based on the weight of zeolite) of phosphorus (calculated as P
2
O
5
) and 0.3~3 wt % of aluminum or magnesium or calcium (calculated as oxide), such as ZSM-5, ZSM-8 or ZSM-11 type zeolite, having a silica/alumina mole ratio of preferably 15~60. The said phosphorus and aluminum or phosphorus and magnesium or phosphorus and calcium containing high silica zeolite having a structure of pentasil may also contain 0.3~3 wt % (based on the weight of zeolite) of nickel (calculated as oxide).
The preparation method of the catalyst of the invention is as follows: mixing the precursor of the inorganic oxides with clay according to a predetermined ratio, adding de-cationized water to obtain a slurry with a solid content of 10~50 wt %, adjusting and maintaining the pH value of the slurry

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