Procedure of switching into condensation mode operation of gas fluidized bed reactor in Unipol gas-phase ethylene polymerization plant was monitored by acoustic emission technique.

Nano-sized silica white(SiO2·xH2O)was prepared through a new gas-liquid phase method with coal gangue and HF as precursors.

The advantages and disadvantages of gas phase and liquid phase processes are compared, and some opinions on further researches on the preparation of nanosized TiO2 powders are also presented.

The developments and technical progresses at home and abroad on PE catalysts for gas phase polymerization have been reviewed in this paper.

Through research and development of special catalyst systems, exploring the production process conditions in condensation state operation , the PE resin for stretch film named DFDA-9030 was produced with gas phase fluid-bed process.

These methods include solid phase method(mechanical pulverization method,solid phase reaction method),liquid phase method(precipitation method,hydrothermal reaction method,micro-lacteous method,sol-gel method,hydrolysis method,solvent vaporization method,electrochemistry method) and gas phase method(atmosphere vaporization method,gas phase c.

The gas phase methods include the flame hydrolysis of TiCl4, the vapor phase oxidation of TiCl4, the vapor phase oxidation of Ti(OR)4, the vapor phase hydrolysis of Ti(OR)4 and the vapor phase pyrolysis of Ti(OR)4 .

These methods may be classified into two types:gas phase method and liquid phase method.