Patent Application
20130090508
1. Technical Field
The present invention relates to a method for preparing 1-octene in the presence of a catalyst system for ethylene oligomerization.
2. Related Art
EP 0608447A1 reports a chromium-based catalyst composition which is used as a catalyst for ethylene oligomerization and/or copolymerization, wherein a chromium containing compound is used as a first component of the catalyst composition; a pyrrole compound is used as a second component of the chromium-based catalyst composition; and a Lewis acid activator and/or a metal alkylate activator is used as a third component of the catalyst component. Further, in EP 0608447A1, it is also pointed out that an optional halogen source may be further used as a fourth component of the catalyst composition, wherein the halogen source may be inorganic halides, or be various types of organic halides.
In JP 0832519, a Sn(OSO2F3)2 compound is used to replace the halogen source as the fourth component in EP 0608447A1, to form a new quaternary chromium-based catalyst composition. However, the activity and selectivity of the quaternary chromium-based catalyst are not significantly improved.
U.S. Pat. No. 5,910,619 reports use of 1,2,3,4,5,6-hexachlorocyclohexane as a modifier, to form a quaternary catalyst composition. Although the activity of the catalyst is relatively improved, the requirement still cannot be met. The performance of the catalyst is expected to be further improved, so as to improve the catalytic activity.
The above ethylene oligomerization methods focus on the research of the catalyst. Although in WO 99/19380, the ethylene oligomerization method is studied, similar to the situations in other patents, the reaction is substantially carried out in an ordinary autoclave, which causes the problem of non-uniform mass transfer and heat transfer. As the reaction is a highly exothermic reaction, and the heat release rate is quick in an initial reaction phase, an excessively high local temperature is generally caused due to a slow heat transfer rate, leading to inactivation of a part of the catalyst, which affects the efficiency of the catalyst. Furthermore, due to a slow mass transfer rate in such autoclave, the catalytic performance of the complex catalyst is influenced, so that the catalytic activity is lowered, and the reaction time is generally long, resulting in increased energy consumption.
The present invention is directed to a method for preparing 1-octene in the presence of a catalyst system for ethylene oligomerization, so that a 1-octene product is prepared in a short reaction time, the activity of the catalyst is high, the selectivity of 1-octene is high, and the energy consumption of the whole method is low. According to the method for preparing 1-octene in the presence of a catalyst system for ethylene oligomerization, before the raw material ethylene is fed to the reactor, a part of the raw material ethylene is premixed with a solvent in a premixer and/or a pipe, for the purpose of sufficient mass transfer between ethylene and the solvent, to increase the solubility of ethylene in the solvent to as high as 20%, thereby improving the yield of the product, and improving the single pass conversion rate of ethylene. The premixed solution of ethylene is then mixed with solutions of components a+b, c and d of the catalyst respectively, and fed to the reactor together with the rest of the raw material ethylene for reaction. The resultant liquid is fed to a separator for separating the product, in which 1-octene is directly used as a comonomer for LLDPE, the solvent is recycled, and the remaining catalyst is recovered. Before being fed to the separator, the resultant liquid is sampled for analysis.
Gas Distributor
The gas distributor is a stainless steel pipe having some pores opened at the middle part, and the diameter of the pores is 0.2-90%, generally 5-70%, and preferably 20-50% of the diameter of the stainless steel pipe.
Catalyst and Solvent
For the catalyst and the solvent used in preparation of 1-octene through ethylene oligomerization, see Chinese Patent entitled “Catalyst Composition for Ethylene Oligomerization and Use thereof” (Application No.: 200610057254.2).
The catalyst includes a chromium compound a, a ligand b containing P and N, an activator c, and a promoter d, wherein
a is chromium acetylacetonate, chromium chloride tetrahydrofuran and/or chromium isooctanoate;
b has a general formula below:
wherein R1, R2, R3, and R4 are phenyl, benzyl, fluorenyl or naphthyl; and R5 is isopropyl, butyl, cyclopropyl, cyclopentyl, cyclohexyl or fluorenyl;
c is methylaluminoxane, ethylaluminoxane, propylaluminoxane and/or butylaluminoxane;
d has a general formula of X1R6X2, wherein X1 and X2 are F, Cl, Br, I or an alkoxy; and R6 is an alkyl or an aryl; and
the molar ratio of a, b, c and d is 1:0.5-10:50-3000:0.5-10.
Reaction Conditions
For the reaction pressure and the reaction temperature in the reactor, see Chinese Patent entitled “Catalyst Composition for Ethylene Oligomerization and Use thereof” (Application No.: 200610057254.2).
The reaction temperature is 30-200° C.; the reaction pressure is 0.5-20.0 MPa; and the time is 0.1-2 hours.
The inlet amount of the catalyst and the solvent satisfies the condition that the concentration of the component a of the catalyst in the reactor is 1-10 ppm, and desirably 1-3 ppm.
The ratio of the weight flow of ethylene fed into the premixer to the total weight flow of ethylene fed into the reactor may be any value that can satisfy the reaction condition, and is generally 0-100%, desirably 20-90%, and preferably 60-80%.
According to the method for preparing 1-octene through ethylene oligomerization of the present invention, before the raw material ethylene is fed to a reactor, a part of the raw material ethylene is premixed with a solvent in a premixer and/or a pipe, the premixed solution of ethylene is mixed with solutions of components a+b, c and d of a catalyst respectively, and then fed to the reactor via pores on a gas distribution pipe located at the bottom of the reactor; the rest of the raw material ethylene is directly fed to the reactor from the top of the reactor for reaction; the reactor is washed with cyclohexane, dried for 1 hour at 100° C. in vacuum, cooled to room temperature, and replaced with ethylene, an ethylene inlet valve is opened, the pressure in the reactor is kept at 5.0 Mpa, the solvent together with the components a+b, c and d are introduced at a certain flow rate, the temperature in the reactor is kept at 50° C., an outlet valve of an overflow tank is opened, the resultant liquid is fed to a separator for separating the product, in which 1-octene is directly used as a comonomer for LLDPE, the solvent is recycled, and the remaining catalyst is recovered. Before being fed to the separator, the resultant liquid is sampled for analysis.
The premixer may be one or more stainless steel pipes having a length to diameter ratio of greater than 20 or a stainless steel autoclave, in which a filler may be filled.
The gas distributor is a stainless steel pipe having some pores opened at the middle part, and the diameter of the pores is 0.2-90%, generally 5-70%, and preferably 20-50% of the diameter of the stainless steel pipe.
Catalyst and Solvent
For the catalyst and the solvent used in preparation of 1-octene through ethylene oligomerization, see Chinese Patent entitled “Catalyst Composition for Ethylene Oligomerization and Use thereof” (Application No.: 200610057254.2).
Reaction Conditions
For the reaction pressure and the reaction temperature in the reactor, see Chinese Patent entitled “Catalyst Composition for Ethylene Oligomerization and Use thereof” (Application No.: 200610057254.2).
The inlet amount of the catalyst and the solvent satisfies the condition that the concentration of the component a of the catalyst in the reactor is 1-10 ppm, and desirably 1-3 ppm.
The ratio of the weight flow of ethylene fed into the premixer to the total weight flow of ethylene fed into the reactor may be any value that can satisfy the reaction condition, and is generally 0-100%, desirably 20-90%, and preferably 60-80%.
Other Reaction Conditions:
reaction temperature: 50° C., reaction pressure: 5.0 Mpa, catalyst formulation ratio a:b:c:d=1:1.05:300:5, modifier: 1,1,2,2-tetrachloroethane, solvent: cyclohexane, total inlet
amount of ethylene: 20 kg/h, total inlet amount of solvent: 13 kg/h.
The process is applicable to preparation of 1-octene through ethylene oligomerization, and has a high catalytic activity and a high selectivity of 1-octene.
a. In the method, the reactants are mixed uniformly, with good effect of mass transfer and heat transfer.
b. High selectivity of 1-octene of greater than 70%.
c. High catalytic activity of the catalyst of greater than 1×106 g product/gCr·h.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010543099.1 | Nov 2010 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2011/000945 | 6/3/2011 | WO | 00 | 12/17/2012 |
