阅读说明：本技术 一种聚烯烃催化剂体系切换的处理方法 (Polyolefin catalyst system switching treatment method ) 是由 王涛 李东华 信强 修青博 陈宁 孙海洋 赵洪江 王希菲 赵同阳 武兴安 于 2020-05-14 设计创作，主要内容包括：一种聚烯烃催化剂体系切换的处理方法,属于催化系统处理领域。其特征在于：聚烯烃催化体系切换时,放空第一种催化剂后,使用催化剂载体硅胶对催化剂输送、返回和加料系统进行清洗,然后输送第二种催化剂。反应初期反应器静电波动由现有水处理方法的-3000V～3000V降低至-1000V～1000V,低负荷时长缩短至24h以内。解决了传统处理方法处理时间长,处理后难脱水、静电波动大或残留水影响催化剂反应活性,低负荷时间长的问题,能显著提高效率,节约成本。(A processing method for polyolefin catalyst system switching belongs to the field of catalytic system processing. The method is characterized in that: when the polyolefin catalysis system is switched, after the first catalyst is emptied, the catalyst carrier silica gel is used for cleaning the catalyst conveying, returning and feeding system, and then the second catalyst is conveyed. The static fluctuation of the reactor at the initial stage of the reaction is reduced to-1000V from-3000V of the existing water treatment method, and the low-load time is shortened to be within 24 h. The problems of long treatment time, difficult dehydration after treatment, large electrostatic fluctuation or long low-load time caused by residual water influencing the reaction activity of the catalyst in the traditional treatment method are solved, the efficiency can be obviously improved, and the cost is saved.)

1. A method for processing polyolefin catalyst system switching, characterized in that: when the catalyst system is switched, the first catalyst is firstly discharged, the catalyst carrier silica gel is used for cleaning the catalyst conveying, returning and feeding system under the blowing of inert gas, and then the second catalyst is conveyed.

2. The method of processing polyolefin catalyst system switching according to claim 1, characterized in that: and blowing the catalyst carrier silica gel by the inert gas under the pressure of 0.2-0.7 MPa.

3. The polyolefin catalyst system switching process according to claim 2, characterized in that: the inert gas blows the catalyst carrier silica gel under the pressure of 0.3 MPa.

4. The method of processing polyolefin catalyst system switching according to claim 1, characterized in that: the blowing speed of the inert gas for blowing the catalyst carrier silica gel is 1-10 kg/min.

5. The method of processing polyolefin catalyst system switching according to claim 1, characterized in that: the specific surface area of the catalyst carrier silica gel is 250-300 m²/g。

6. The polyolefin catalyst system switching process according to claim 5, characterized in that: the specific surface area of the catalyst carrier silica gel is 280m²/g。

7. The method of processing polyolefin catalyst system switching according to claim 1, characterized in that: the catalyst carrier silica gel is subjected to high-temperature treatment before use, and the treatment temperature is 260-600 ℃.

8. The method of any of claims 1 to 7, wherein the method comprises: the polyolefin catalyst system is a dry powder type catalyst system.

Technical Field

A processing method for polyolefin catalyst system switching belongs to the field of catalytic system processing.

Background

In order to optimize the product structure and improve the economic benefit in the production process of polyolefin and the like, the product brands need to be switched, and some catalyst systems even need to be replaced, but the compatibility among different catalyst systems is often poor, so that the problem of mutual poisoning can occur, and the switching failure is caused by agglomeration due to the factors of low catalyst activity, more polyolefin product fine powder, large reactor static electricity and the like in the switching process.

In order to solve the problem of mutual poisoning in the switching process of incompatible catalyst systems in polyolefin production, the currently adopted method is a water washing method, namely when the catalyst systems need to be switched, firstly, a first catalyst is emptied, then water is injected into the catalyst systems to completely deactivate and wash away the first catalyst residues, and then, refined nitrogen is used for completely blowing off the water remaining in the catalyst systems. However, the method has two main problems at present, namely, the catalyst activity is reduced by the residual water, so that more fine powder is brought, the static electricity is large and the like; and secondly, the residual water is extremely difficult to remove due to the dead angles of inverted spraying, emptying and the like on the catalyst system pipeline and the complex structures of a catalyst feeder and a filter, a large amount of refined nitrogen is consumed for long-time blowing, and the efficiency is low. There is therefore a great need for a more reliable and efficient polyolefin catalyst system treatment technique.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method overcomes the defects of the prior art, provides a more reliable and efficient method for processing a catalyst system when a polyolefin catalyst system is switched, and is applied to a gas-phase fluidized bed polyethylene production process to reduce the processing time, reduce the static fluctuation at the initial stage of reaction and shorten the low-load production time after processing, thereby realizing the improvement of the efficiency and the reduction of the total cost.

The technical scheme adopted by the invention for solving the technical problems is as follows: when the polyolefin catalysis system is switched, the first catalyst is firstly released, the catalyst carrier silica gel is used for cleaning the catalyst conveying, returning and feeding system under the blowing of inert gas, the typical cleaning time is 10-50 minutes, and then the second catalyst is conveyed.

The catalyst carrier silica gel is adopted to be beneficial to protecting the catalyst and avoiding the activity of the catalyst from being influenced. Since the silica gel is used as the carrier of the catalyst, the activity of the second catalyst can be protected to the greatest extent by using the catalyst carrier silica gel for cleaning according to homology, and the catalyst carrier silica gel has high purity and contains few impurities.

Preferably, the inert gas blows the catalyst carrier silica gel under the pressure of 0.2-0.7 MPa, and more preferably blows the catalyst carrier silica gel under the pressure of 0.3 MPa.

Preferably, the blowing speed of the inert gas is 1-10 kg of catalyst carrier silica gel per minute.

Preferably, the specific surface area of the silica gel of the catalyst carrier is 250-300 m²/g。

Preferably, the specific surface area of the silica gel of the catalyst carrier is 280m²/g。

Preferably, the catalyst carrier silica gel is subjected to high-temperature treatment before use, the treatment temperature is 260-600 ℃, and the pretreatment aims at activating the cleaning capacity of the catalyst carrier silica gel, reducing impurities in the catalyst carrier silica gel and further preventing the activity of a second catalyst from being influenced.

Preferably, the polyolefin catalyst system is a dry powder catalyst system.

Compared with the prior art, the invention has the beneficial effects that: successful switching between incompatible polyolefin catalyst systems is realized; the catalyst switching treatment time is shortened to be within 8 hours from more than 32 hours of the existing water treatment technology; after the catalyst system is replaced, the electrostatic fluctuation of the reactor at the initial stage of the reaction is reduced to-1000V from more than-3000V of the prior water treatment technology to 3000V; the low-load time is shortened to within 24 hours from more than 72 hours of the existing water treatment technology, so that the switching cost is greatly saved, and the efficiency is improved.

Detailed Description

Examples 1 and 3 are preferred embodiments of the present invention, and the present invention will be further described with reference to the following examples.

Example 1

A method for switching polyolefin catalyst systems comprises selecting catalyst carrier silica gel as silica gel 955 produced by GRACE company to clean the catalyst system. The specific surface area of the silica gel of the catalyst carrier is 280m²The treatment temperature is 500 ℃, the blowing speed of the catalyst carrier silica gel is about 1.5kg/min, and the inert gas pressure is 0.2 MPa.

The polymerization line of a fluidized bed high density polyethylene device adopting a chromium-based polyethylene catalyst system is switched to a narrow-distribution metallocene polyethylene catalyst system: after emptying the chromium-based catalyst, the catalyst delivery, return and feed system was cleaned with catalyst support silica gel for 30 minutes and a second catalyst was delivered.

After switching, the reaction is quickly established, the static fluctuation is-800V, and full-load production is quickly realized after 7-hour low-load transition.

Example 2

A method for switching polyolefin catalyst system comprises selecting catalyst carrier silica gel as "silica gel 955" produced by GRACE, and having a specific surface area of 300m²The treatment temperature is 600 ℃, the blowing speed of the catalyst carrier silica gel is about 2.5kg/min, and the inert gas pressure is 0.7 MPa.

The polymerization line of a fluidized bed high density polyethylene device adopting a chromium-based polyethylene catalyst system is switched to a wide-distribution metallocene polyethylene catalyst system: after emptying the chromium-based catalyst, the catalyst delivery, return and feed system was cleaned with catalyst support silica gel for 10 minutes to deliver a second catalyst.

After switching, the reaction is quickly established, the static fluctuation is-900V, and full-load production is quickly realized after 12-hour low-load transition.

Example 3

A method for switching polyolefin catalyst system comprises selecting catalyst carrier silica gel as 'ES 70' produced by INEOS company, and having specific surface area of 250m²The treatment temperature is 260 ℃, the blowing speed of the catalyst carrier silica gel is about 3kg/min, and the inert gas pressure is 0.3 MPa.

Switching a fluidized bed linear low density polyethylene device adopting a titanium polyethylene catalyst system to a wide distribution metallocene polyethylene catalyst system: after emptying the titanium polyethylene catalyst, the catalyst carrier silica gel is used for cleaning the catalyst conveying, returning and feeding system for 20 minutes, and a second catalyst is conveyed.

After switching, the reaction is quickly established, the electrostatic fluctuation is-1000V, and full-load production is quickly realized after 22-hour low-load transition.

Example 4

A method for switching polyolefin catalyst systems comprises selecting catalyst carrier silica gel as 'ES 70' produced by INEOS company, and having specific surface area of 280m²The treatment temperature is 400 ℃, the blowing speed of the catalyst carrier silica gel is about 10kg/min, and the inert gas pressure is 0.2 MPa.

Switching a fluidized bed linear low-density polyethylene device adopting a titanium polyethylene catalyst system to a narrow-distribution metallocene polyethylene catalyst system: after emptying the titanium polyethylene catalyst, the catalyst carrier silica gel is used for cleaning the catalyst conveying, returning and feeding system for 10 minutes, and a second catalyst is conveyed.

After switching, the reaction is quickly established, the electrostatic fluctuation is-700V, and full-load production is quickly realized after 8-hour low-load transition.

The processing time of the catalyst system can be shortened by 24 hours and the low-load time after the start can be shortened by 48 hours in each switching, the productivity can be effectively improved by 720 tons, and the efficiency can be increased by about 72 ten thousand yuan in terms of the ton benefit of the product of 1000 yuan/ton.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.