Slurry Catalyst For Polyethylene On The Improvement Of Quality Control In Production Process

Since the advent of the type of feed slurry polyethylene catalyst applied for the Unipol process, it has developed rapidly in the world. Because compared with the traditional solid powder catalyst, the activity increased by 4 ～6 times, resin product less residue ash, product processing and application performance have been improved. After years of efforts of researchers, many domestic companies have realized the type of feed slurry polyethylene catalyst localization. SLC-S developed by shanghai leader catalyst Co. Ltd. is one of them, which can produce HDPE,LDPE and LLDPE products. This research subject mainly discussed the influence on the quality of the product of the various control indicators in the SLC-S’s production and application process. Discussed the impact factors from the view of each control indicators in the production process of SLC-S, which has great significance for the company to improve the stability of the catalyst in the production process and improve product quality and reduce the production cost.This article introduced the SLC-S’s mother liquor preparation, slurry preparation, spray-dried and homogenized mix four main production processes and analytical methods. Through the production experiments and summarizes, we found that the quality performance of SLC-S catalyst is mainly affected by the THF’s content, dry powder particle size and other indicators. However, the indicators are affected by many factors in the production process. The main discussion and the results are as follows:1. Analyzed the causes of insolubles during the mother liquor preparation process, in the contrast test examined the influence factors, such as the amount of solvent, stirrer functioning and mother liquor preparation temperature, we found that when preparing the mother liquor, the percentage of the magnesium compound/THF should be controlled not higher than 4.17, Or prone to form insolubles in the mother liquid preparation process. In addition, agitator type and speed can also affect the dissolution2. Discussed the influence of the product particle size and THF content on the quality of the catalyst, the factors resulting fluctuations in the two indicators in the process of production:Mainly analyzed the factors influencing the particle size, such as the spray particle size, slurry solids content, the feed amount per unit of time, etc; Spray speed increases, the particles become smaller, the slurry solids content and feed rate per unit time increases, particles become bigger. Analysed the factors affecting the content of THF,such as the spray air temperature, drying time, spray speed, magnesium titanium product ratio, coolant temperature, etc:the spray air temperature, drying time, spray speed change will directly affect the content of THF, Introduced the solvent selection basis in homogenized mix process, compared the dehydration effect using domestic and imported white oil in the preparation of catalysts and the effect on catalyst activity, using imported white oil easily dehydrated, the catalyst activity is higher.3. Analysed the factors affecting the catalyst activity, mainly discussed the impact of the purity of the raw material, the cleanliness of dry gas and containers, the active ingredient content and operation of storage and transportation process may cause, and the usage of SLC-S catalyst in ethylene polymerization device.