This project belongs to the field of polymer materials and new catalysts in the new material category. High-performance polyethylene is the main basic material for the production of mid-to-high-end plastic products such as high-quality pipes, films and blown hollow containers. However, the domestic polyethylene production technology level is backward, high-performance products are lacking, and it has long relied heavily on imports. The fundamental reason is the lack of core catalyst technology for producing high-performance polyethylene special materials.  Chromium based catalysts use chromium oxide (CrO3) as the active material and are one of the most important catalyst varieties in the polyethylene industry. In recent years, with the continuous expansion of polyethylene applications and the continuous advancement of production processes, its advantages in the development and production of high-performance resins have been fully reflected. It can produce polyethylene products with wide molecular weight distribution. The resin has superior processability and mechanical properties, high melt strength, and film bubble stability, orientation, melt fracture resistance and ductility viscosity are much better than those of Ziegler-Natta and single-active site catalysts represented by metallocene compounds, and can achieve high-performance broad-peak special material products that require multiple reactors in series to produce in one reactor.  However, traditional chromium-based catalysts have the problems of long initiation time and low titanium modification efficiency, which seriously limits their application in the most mainstream gas-phase condensation process at home and abroad. Therefore, 90% of my country's current gas-phase processes still use Ziegler-Natta catalysts to produce universal polyethylene products, while high-performance and wide molecular weight distribution polyethylene relies on imports.  The project has achieved the following technical innovations, including: (1) invented a preparation method for chromium oxide catalysts modified by organic magnesium compounds, which solved the problem of long initiation time in the application of chromium catalysts in gas-phase condensed polyethylene process;(2) Aiming at the long-standing problem of poor titanium modification efficiency of chromium catalysts, a new composite chromium oxide catalyst preparation method that adopts "separate loading and co-calcination and activation" was invented.  A new SLH chromium-based catalyst suitable for gas-phase condensed process was developed, and stable and efficient production of chromium-based catalysts in gas-phase condensed process was achieved for the first time in China. SLH catalysts have been successfully applied to the Unipol process and Innovene G process, which currently have the highest market share in the world, basically achieving full coverage of gas-phase processes.  Industrial application shows that the average polymerization activity of the SLH catalyst in the condensed state (condensation depth 10%) is 7000gPE/gcat, and in the ultra-condensed state (condensation depth ≥10%) the average polymerization activity reaches 4100gPE/gcat. The comprehensive performance has reached the international advanced level of similar catalysts.  SLH catalyst obtained 2 China invention patents, 2013~In 2015, a total of 19.4784 million yuan was added, profits were 4.0857 million yuan, and foreign exchange earned by exports was 475,200 US dollars.  In terms of the development of high-performance and wide-molecular-weight distribution polyethylene products, SLH catalysts have achieved the large-scale industrial application of high-performance special materials represented by large hollow automobile fuel tank materials in gas-phase condensed state processes for the first time in China, filling the domestic gas-phase condensed state process. The gap in high-performance broad-peak polyethylene catalytic technology and production technology has improved the level of my country's gas-phase polyethylene products and promoted the sustainable development of the polyethylene industry.