Phillips catalyst is an important kind of industrial polyethylene catalyst. As early as in the late 1970s, CrO 3 was substituted by chromium (III) acetate for the preparation of Phillips catalyst on the industrial scale owing to health and environmental considerations. There is still considerable research focusing on the relations between the preparation process and catalyst properties in academics. In this work, the supporting mechanism of chromium (III) acetate on silica has been studied by Thermogravimetry-Differential Thermal Analysis (TG-DTA), and Electron Spin Resonance (ESR), in comparison with that of supporting CrO 3 on SiO 2 . The basic chromium (III) acetate supported on high surface area silica gel decomposed differently from that for bulk basic chromium acetate when decomposition temperature was decreased by 15• C. The decomposition temperature was 299• C for Cr 3 (OH) 2 (Ac) 7 /SiO 2 catalyst precursor, which would be firstly transferred into CrO 3 followed by supporting on silica surface as chromate species. The further weight loss came from thermal inductive reduction of chromate species into Cr 2 O 3 , which was also supported by the results of colors of catalysts. Moreover, with the increase of chromium loading of Cr 3 (OH) 2 (Ac) 7 /SiO 2 , such thermal inductive reduction became more severe. ESR spectra of Cr 3 (OH) 2 (Ac) 7 /SiO 2 and CrO 3 /SiO 2 catalyst precursors showed that a small amount of supported Cr 5+ can exist stably on silica gel surface at temperatures higher than 200

Cr/SiO2 catalysts are important industrial ethylene polymerization catalysts, mainly including Phillips catalyst (also called oxo chromium/SiO2) and silyl chromate/SiO2 systems (named as SC/SiO2, also called UCC S‐2 catalyst). Compared with Phillips catalyst, SC/SiO2 catalyst is not fully investigated. In this work, SC/SiO2 catalyst was prepared, and triethylaluminum or triisobutylaluminium was used as cocatalyst for ethylene homopolymerization. The effects of cocatalysts on polymerization kinetics and polymer microstructure were investigated. It is found that the kinetic curves using SC/SiO2 catalyst in the presence of triethylaluminum or triisobutylaluminium seem to be a hybrid type composed of two types of basic polymerization kinetics: one is a fast built‐up and fast decay type, and the other is a slow built‐up and slow decay type, which indicates the existence of two types of polymerization active sites. Plausible mechanisms of the formation and transformation of active sites were proposed to rationalize the unique polymerization behavior. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

Tight sand reservoir is usually characterized by high heterogeneity and complex pore structure, which makes the permeability calculation a big challenge and leads to difficulties in reservoir classification and productivity evaluation. First, five different Hydraulic Flow Units and respective Porosity-permeability relations were built based on core dataset from Kekeya block, Tuha Basin; and then with BP Neutron Network method, flow unit was classified for un-cored intervals using normalized logging data, and permeability was calculated accordingly. This improved the accuracy of permeability calculation and helped a lot on un-cored reservoir evaluation. In addition, based on porosity, permeability and flow unit type, a new reservoir grading chart was set up by incorporating the testing or production data, which provides important guidance for productivity prediction and reservoir development.

Although an important industrial catalyst for producing high density polyethylene, the SiO 2 -supported organosilyl chromate UCC S-2 catalyst has not been fully investigated compared with the SiO 2 -supported oxo chromium Phillips catalyst. In this work, gas phase ethylene polymerization by S-2 catalysts (Cat-1, Cat-2, and Cat-3) was carried out in a high-speed stirredautoclave reactor. The effects of temperature, time, and pressure on kinetics, activity, and product properties were studied. All kinetics were typical built-up types with slow decay. Compared to the simple physical mixtures of Cat-1 and Cat-2, Cat-3 showed higher activity and its product had a broader molecular weight distribution, indicating new active species induced during blending of Cat-1 and Cat-2 in n-hexane. The innovation by a simple catalyst technology created a new application to meet market demands.