Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Reexamination Certificate
1998-12-23
2002-01-29
Griffin, Steven P. (Department: 1754)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
C208S113000, C208S120010, C208S122000, C502S063000, C502S064000, C502S068000, C502S071000, C502S077000, C502S079000, C502S080000, C502S084000
Reexamination Certificate
active
06342153
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to catalysts for hydrocarbon conversion. More particularly, the invention relates to pillared clay catalysts for catalytic pyrolysis of heavy oil or residual feedstock to give the maximum yield of ethylene, propylene and butylene products and to their preparation method and application.
2. Description of Prior Art
Light olefins, including ethylene as a principal variety of the kind, are important industrial chemicals, for which the demand is increasing steadily. In the prior art, ethylene was mainly produced by means of thermal cracking process from light oil feedstock, while propylene and butylene were mainly prepared by fluid catalytic cracking (FCC) process with solid acidic catalysts.
Catalytic pyrolysis process (CPP) with heavy oil or residual feedstock is actually an art of introducing catalyst into the thermal cracking process. By the CPP process, heavy oil or residual feedstock can be converted into at relatively high yield of ethylene and propylene products at a reaction temperature lower than that of the prior thermal cracking process. The catalysts used for catalytic pyrolysis processes need to have not only the essential properties, such as good attrition resistance index and appropriate bulk density, possessed by the commercial FCC catalyst but also the distinguishing characteristics superior to the conventional FCC catalyst as follows:
(1) High Hydrothermal Stability
The reaction temperature for conventional FCC process is 460° C.-520° C., and reaction for thermal cracking process is 550° C.-800° C. Although the reaction temperature for CPP is lowered because of the use of the catalyst, it is still in the range of reaction temperatures for thermal cracking process Therefore, the catalysts used for CPP need to have high hydrothermal stability.
(2) High Converting Activity for Cracking Heavy Oil or Residual Feedstock
As the CPP technique is a process of cracking heavy oil to obtain ethylene and propylene products, the catalysts used for the process need to have high catalytic cracking activity that can convert effectively heavy oil or residual feedstock into light olefins.
(3) Good Light Olefin Selectivity
The catalysts used for CPP need to have high yields of ethylene, propylene and butylenes, low yield of dry gases and adequate coke yield to maintain thermal equilibrium of reaction and regeneration units.
The prior catalysts containing pillared clays reported in the literature are all FCC catalysts used for carbonium-ion reaction but none for the catalytic pyrolysis reaction. For example, a pillared clay catalyst reported in the Chinese patent of CN1107080A is for use in the conventional FCC process to yield more isobutene and isoamylene products (MIO catalyst). In the catalyst of the prior art, pillared rectorites prepared with a pillaring agent having a OH/Al gram mole ratio of 2.0 was used as activity component. Although the pillared clay component could improve the activity of the catalyst, it had in the meantime an adverse effect on the attrition resistance of the catalyst, hence the content of pillared clay in the catalyst of the patent is limited to less than 50 wt %. As the amount of the active component cannot be increased, consequently, the stable activities of the prior catalyst can hardly be improved. Also, in the patent the attrition resistance index data are not shown, and it implies that the attrition resistance of the prior pillared clay catalysts is inferior to commercial FCC catalysts. The prior catalysts are not catalytic pyrolysis catalysts with high stable activities and good attrition resistance index, therefore they cannot be commercialized.
The Chinese patent ZL CN 96103411.4 of the present applicant discloses a poly (vinyl alcohol) modified pillared clay catalyst for yielding more light olefin products. However, it is rather a MIO catalyst used for conventional FCC process to produce isobutene and isomyalene, than catalytic pyrolysis catalyst used for CPP to produce ethylene and propylene. In the catalyst, polyvinyl alcohol-modified pillared clay vinyl alcohol can improve the activity of catalyst, but at the same time has negative effect on the attrition resistance index of the catalyst. In the patent there is also no data about attrition resistance index and catalytic pyrolysis properties of the catalyst, this implies that the catalyst does not possess good attrition resistance index and catalytic pyrolysis properties. It is impossible to withstand the severity of CPP. Up to now the catalyst has not been commercialized.
In the Chinese patent of Z L 92109775.1 the present applicant disclosed a CCP method for petroleum hydrocarbon, wherein a pillared clay catalyst for conventional catalytic cracking process, CRP-1 (commodity trademark) catalyst and a mixture of the above two catalysts were used. Among them, the pillared clay catalyst was a pillared rectorite catalyst containing 5 wt % USY molecular sieves prepared according to the process disclosed in Z L CN 87104718, which was only a conventional FCC catalyst; and the CRP-1 catalyst was prepared by using high silicon pentasil structure zeolites containing rare earth in framework (CN 1058382A), which was also used in conventional FCC process to yield more light olefin products. Although the pillared clay catalyst of the patent had an ethylene yield of over 20 wt % and the total C
2
=
—C
4
=
yields of around 50 wt % at an average reaction temperature of 700° C., it did not result from the catalyst after the deactivating treatment at 790° C. or 800° C. for 17 hours with 100% steam. Instead, only the performance of the catalyst treated at 760° C. for 6 hours with 100% steam, indicated that the hydrothermal stability of the catalyst is impossible to meet the severity of the CPP. Up to now, no catalytic pyrolysis catalyst with good attrition resistance index, high hydrothermal stability and good selectivity to ethylene and propylene is reported in any of the prior art.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a series of pillared clay catalysts that can be used in catalytic pyrolysis process for cracking heavy oil or residual feedstock to yield more ethylene, propylene and butylene products. The said catalysts comprise pillared clays with high alkalized degree, molecular sieves, matrix, bonding agents and modifying compositions. The catalysts have excellent hydrothermal stability, high catalytic activity for converting heavy oil or residual feedstock, good selectivity to light olefins, adequate coke yield and attrition resistance index and apparent bulk density in accordance with demands of FCC catalyst as well.
Another object of the present invention is to provide a method for preparation of the catalysts comprising the steps of mixing slurries of all the components of said catalysts, spray drying to form microspheric shapes, preparing pillaring agents with high alkalized degree, pillaring reaction and adding modifying components.
A further object of the present invention is to provide applications of the said catalyst products. The catalysts of the present invention are suitable for use as catalysts for hydrocarbon conversion, including CPP catalyst for producing ethylene and propylene, MIO catalyst for maximum isobutene and isoamylene yields, and FCC catalyst for cracking heavy oil or residual feedstock into gasoline and light cycle oil. Besides, the catalysts of the present invention can also be used as adsorbents and catalyst supports.
DETAILED DESCRIPTION OF THE INVENTION
The catalysts of the present invention comprise the following compositions:
1. 30-75 wt % pillared clay compositions prepared by aluminum pillaring agents of high alkalized degree;
2. 10-40 wt % Bonding agent compositions of inorganic oxides
3. 0-30wt % High silicon zeolites with pentasil structure or y-type zeolites or mixtures thereof.
4. 0-10 wt % Modified compositions; and
5. 0-50 wt % Kaoinite matrix compositions.
Herein the pillared clay compositions with high alkalized degree are imp
Chen Zhengyu
Guan Jingjie
Liao Yi
Liu Qinglin
Wang Xieqing
China Petro-chemical Corporation
Griffin Steven P.
Ildebrando Christina
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