Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And group iii or rare earth metal or lanthanide containing
Reexamination Certificate
2001-08-10
2004-01-13
Dunn, Tom (Department: 1725)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And group iii or rare earth metal or lanthanide containing
C502S077000, C502S341000, C502S342000, C502S343000
Reexamination Certificate
active
06677263
ABSTRACT:
FILED OF THE INVENTION
The present invention relates to a catalytic promoter used in the process of fluid catalytic cracking of hydrocarbons in petroleum refining field. More particularly, it relates to a catalytic promoter used in the process of fluid catalytic cracking of hydrocarbons to reduce olefin content in gasoline from catalytic cracking process, and to the preparation thereof.
BACKGROUND OF THE RELATED ART
Gasoline octane number is one of the most important indexes to evaluate motor gasoline. The operating conditions comprising short contact time at an elevated temperature in the presence of an ultrastable zeolite catalyst are now generally employed in a unit for catalytic cracking in a refinery in order to increase gasoline octane number. Such a technique, however, results in increased olefins in gasoline from catalytic cracking process. Olefins in gasoline constitute the major reason for the high amount of contaminants from automobile exhaust emissions. It is necessary to reduce the olefin content in gasoline to meet environmental requirements. Thus, there's a great need to reduce olefin content in catalytically cracked products—gasoline, and meanwhile to increase or maintain gasoline octane number.
The use of catalytic cracking catalysts containing high silica zeolite, ZSM-5, to increase gasoline octane number, is well known to one skilled in the art. As disclosed in the art, a ZSM-5 zeolite can be incorporated into a catalytic cracking catalyst as one of the active components. Alternatively, the ZSM-5 zeolite as a single active component can be made into an additive catalyst which is then added to a unit for catalytic cracking in combination with a conventional catalytic cracking catalyst. The amount of the ZSM-5 zeolite added can vary widely; it can be either as little as 0.01-1 wt % or as much as 5-10 wt % or even more, based on the total weight of the catalyst. As disclosed in U.S. Pat. No. 4,929,337, a ZSM-5 zeolite modified with Ga is used as an active component for aromatization. Alkanes and olefins are subjected to cracking/aromatization by means of the shape selective cracking/aromatization component. The shape selective aromatization component converts alkanes and olefins to aromatic hydrocarbons. These catalysts, however, are mainly used in catalytic cracking to increase gasoline octane number, without an effect of reducing olefin content in gasoline. A process of catalytic cracking of heavy oils to increase gasoline octane number is disclosed in U.S. Pat. No. 4,867,863. A catalyst containing 0.5-5% HZSM-5 zeolite was used in the patent, with the result of an increased gasoline octane number. But the effect of reducing olefin content in gasoline was not indicated.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a catalytic promoter, which can not only reduce olefin content in gasoline but also increase gasoline octane number, at the same time, increase the yield of very useful industrial feedstock, lower olefins. It is another object of the present invention to provide a method for preparing said catalytic promoter.
DETAILED DESCRIPTION
The present catalytic promoter for the catalytic cracking of hydrocarbons comprises a HZSM-5 zeolite in an amount of 5-65%, and preferably 20-50% based on weight of the catalytic promoter. The HZSM-5 zeolite is modified with zinc and at least one element selected from a group consisting of P, Ga, Al, Ni and rare earth elements or their mixtures. The amount of the modifying elements in HZSM-5 can be adjusted depending on the catalytic cracking feedstock, the main catalytic cracking catalyst and the desired catalytic cracking effect, it being preferably 0.01-10.37 wt %, and more preferably 0.1-5.0 wt %. The applicant also discovered that the most desirable results are achieved by utilizing the present catalytic promoter containing 23%-95.3% by weight of zinc based on the total weight of the modifying elements.
The HZSM-5 zeolite used in this invention can be any of the commercially available products. The HZSM-5 zeolite with a SiO
2
/Al
2
O
3
ratio of preferably 20-500, more preferably 30-200, and most preferably 30-100, is highly preferred.
ZSM type series zeolites whose representative is HZSM-5 are such a kind of zeolite that have high silica content and structure of three-dimensional crossed straight channel. They are characterized by lipophilicity, hydrophobicity and good thermostability etc. The majority of their pores are about 5.5 Å in size. The catalytic activity of ZSM type relies on the surface acidity resulting from acid sites therein. Most of acid sites are located in the cavities of zeolites. ZSM type zeolites exhibit specific shape-selective catalyzing as a result of the particular pore path structure in conjunction with acid sites. Different acid-catalyzed reactions require different strength of acidic sites. The strength of acidic sites has a direct effect on the selectivity of a reaction. It is necessary to suitably adjust the amount, strength and distribution of acidic sites in the zeolites in order to induce a desirable reaction. For such a purpose, to modify zeolites is one of the most effective methods. In present invention some elements are incorporated into zeolites to effect such modification.
There are a wide variety of methods for incorporating some elements into zeolites, such as ion-exchange, impregnation and high temperature processing as disclosed in CN1,057,408A. The location where the incorporated element is in the zeolite, varies with the method employed, and has an influence on the properties of the zeolite. A modified zeolite is prepared by the impregnation method in present invention. The method of impregnation is simple and readily carried out. The impregnated zeolite or catalyst is dried and calcined, and then the modifying element is deposited on the zeolite and bound thereto, acting to adjust the acidity of the zeolite. The typical method for a zeolite modification in present invention comprises impregnating a HZSM-5 zeolite with an aqueous solution containing a compound of a modifying element and then drying and calcining the impregnated zeolite. Said compound can be any of water soluble compounds such as halide and inorganic or organic acid salts of the modifying element, as long as the modifying element therein can deposit on the zeolite and bind thereto during impregnation. Chloride, nitrate and sulfate salts are preferred. The zeolite can be impregnated with different solutions containing compounds of different modifying elements simultaneously or separately. The concentration of the modifying element in an aqueous solution is determined by the content of modifying elements required in said zeolite. The zeolite is normally impregnated with the above aqueous solution at 10-60° C. for 1-30 hours. The impregnated zeolite is usually dried at 100-160° C. for 1-8 hours and then calcined at an elevated temperature of 500-600° C. for 1-8 hours prior to pulverization. Fine powders of particle size greater than 150 mesh American Standard Screen are collected.
When modification of said zeolite is completed as described above, the present catalytic promoter is subject to a forming process to produce the product of final use. An effective amount of supports and binders also need to be added during forming. Preferably a support in an amount of 15-60% and a binder in an amount of 10-40% based on the total weight of the formed catalytic promoter product are added. It is preferred to use at least one material selected from ZrO
2
, P
2
O
5
, clay, diatomaceous earth or sepiolite or mixtures thereof as the support. At least one material selected from alumina sol, silica-alumina sol, aluminum phosphate sol or mixtures thereof is preferably used as the binder.
The catalytic promoters are formed as follows. Said modified HZSM-5 zeolite is added into an effective amount of binders together with an effective amount of the support to produce a mixture. The obtained mixture is then subject to a slurrying and homogenizing step, while the pH is controlled at 2.5-4.
Gong Xuhui
Hao Daijun
Liu Danhe
Liu Jinlong
Wang Longyan
Birch & Stewart Kolasch & Birch, LLP
China Petro - Chemical Corporation
Cooke Colleen P.
Dunn Tom
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