The Polypropylene (PP) plant of China Petroleum & Chemical Corporation (hereinafter referred to as Sinopec) Jinan Branch Company adopts a domestically produced single loop reactor technology. After the plant was put into operation in 1998, the domestically-made high-efficiency PP catalyst N-II has been used. In 2002, after the trial production of T30S in the PP plant industry, DQ series catalysts produced V30S, Z30S, H30S, biaxially oriented PP (BOPP) special resin T36F and high-grade non-woven special material JNW28 and other products. With this catalyst, the device operates smoothly, the product quality is excellent, the catalyst consumption is at a low level, and the production cost is effectively reduced.
1 Characteristics of DQ catalyst DQ catalyst is a new-generation PP spherical high-rescue catalyst developed by Sinopec Beijing Research Institute of Chemical Industry. It can be applied to homopolymerization, random copolymerization and block copolymerization to produce PP with high ethylene content. Widely used in various polymerization processes. The technical characteristics of the catalyst are: (1) high activity, activity is greater than or equal to 50kg/g (liquid phase bulk polymerization, 70 °C, 2h), long active center (greater than 6h); (2) catalyst and its preparation The polymer is spherical, the catalyst particle size can be properly adjusted according to the process needs; (3) hydrogen sensitivity is good, the polymer melt flow rate (MFR) adjustable range is wide (homopolymer 0.2-150.0g/10min) (4) The polymer product has a high isotactic index and good adjustability; (5) the polymer has a high apparent density (greater than or equal to 0.47 kg/m3); (6) the polymer product has excellent performance.
2 Application of DQ catalyst in PP plant 2.1 Production of traditional PP grade DQ series catalyst was started in PP plant in the beginning of 2002, firstly producing T30S and Z30S products. According to the characteristics of the D0 catalyst, the hydrogen concentration was adjusted from 400 μL/L to 500 μL/L, and the catalyst injection amount was adjusted down by 20%. Other parameters remained unchanged. During the transformation process, the equipment operation was stable, the opening of the discharge valve of the ring pipe and the fluctuation of the material level of the high-pressure propylene flash tank (D-301) were significantly reduced, but the axial pump power increased slightly by 2-3 kW. The first batch of PP products produced using the new catalyst was analyzed and tested, and the powder ash content was reduced by 30 μg/g. All the other quality indicators were the same as those produced using the N-II catalyst. Since then, the use of DQ series catalysts to produce Z30S has been successful.
According to the technical data obtained during the production of T30S and Z30S and the good operating conditions of the device, the production of H30S using the DQ catalyst continues to be successful.
2.2 Production of BOPP special resin T36F In 2004, the BOPP production line of the PP downstream plant of Sinopec Jinan Branch was started, and the raw material T36F used was provided by the device. The isotactic index of the product is required to be stable at 95.5%-96.5%, MFR at 2.6-3.0 g/10min, and ash content not higher than 150 μg/g. The production of high-quality PP resin using a single loop reactor process is very difficult to operate, and the fluctuation of the production process parameters must be strictly controlled.
Due to the lower isotactic index of PP produced by DQ catalyst, its hydrogen modulation performance is slightly worse than that of N-II catalyst, the MFR of the product is more stable, coupled with its better fluidity, and the production of low gauge index products is not likely to cause loop out Materials, D-301 and other key parts are blocked, so DQ catalyst was selected for the production of membrane material T36F.
In August 2004, trial production of the first batch of T36F was carried out. All parameters were adjusted according to the performance indicators of the DQ catalyst. The test was carried out until 12 hours. The product's isotactic index reached 95.8%, the MFR was stable at 2.9g/10min, product quality was controllable, and the device continued to operate stably. The analysis and test of the product showed that the performance indicators fully meet the T36F quality requirements.
The T36F products produced by the BOPP manufacturers trial, pull the film speed of 370m/min or more, other excellent performance indicators.
2.3 Product Quality of PP Since August 2004, the device has been able to produce various grades of PP with MFR of 2-40g/10min and isotactic index of 94%-98% using DQ catalyst. The catalyst can be achieved only by adjusting the amount of hydrogen added. The entire production process is stable and the product quality is stable. More than 85% of the products such as T30S, T36F, V30S, Z30S, JNW28, and H30S produced have reached Grade 1 products, and the qualified rate of transition materials has reached 100%. After analysis and testing of the products, all performance indicators have met the quality requirements of the products, and some of the product quality is shown in Table 1.
Table 1 Performance of PP Products Produced Using DQ Catalysts
Tab.1 Properties of the PP resin prepared with DQ catalyst
PP grade T30S T36F V30S Z30S JNW28 H30S
Hydrogen addition amount/(μL·L-1) 450 440 1500 2450 1500 2900
MFR/[g·(10min)-1] 2.56 2.88 17.10 26.32 35.14 32.10
Alignment index, % 96.2 95.8 96.3 96.2 97.6 96.8
Powder Ash/(μg·g-1) 126 126 123 123 123 122 134
Yield tensile strength/MPa 33.16 34.42 35.95 35.62 35.57 38.45
Elongation at break,% 501
Number of "fisheyes" (0.2-0.7mm)/(pieces per m-2) 160 164 168 164 180
Note: The quality grades are all excellent grades.
3 Factors influencing the activity of DQ catalyst 3.1 Effect of hydroxysulfur (COS) content on catalyst activity Based on the change in catalyst activity, it was found that the catalyst activity was related to the quality of propylene. The change of COS content in propylene is significant, and it has a significant effect on the activity of the catalyst; when the COS content is high, the content of impurities such as CO2 and dimethyl sulfide is changed. Therefore, the factor affecting the quality of propylene is the COS content. The use of each batch of procatalyst in 2006 was measured based on different production grades. From Table 2, it can be seen that the greater the COS content in propylene, the lower the catalyst activity. When the raw material propylene has a COS content of less than 10 μg/g, there is little effect on the catalyst.
3.2 Measures to improve the activity of the main catalyst 3.2.1 Improve the relevant process of the device by analyzing the upstream and downstream related device process, and finally determine
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