A multi-reactor stopped-flow apparatus has been developed to study gas-phase olefin polymerization at short times under industrially meaningful reaction conditions. A simplified single-phase 1D dynamic model of the reactor was used to develop an estimator of the polymerization rate from the recorded measurements of temperature, pressure, and flow rates. This combined hardware/software tool was used to investigate the difference between two commercial catalysts that showed different activity profiles in a standard laboratory reactor. Using the temperature and rate profiles generated with this new reactor, it was shown that one of the catalysts exhibited extremely rapid light off and an associated initial temperature spike. Since the observed activity of this catalyst was much lower than that of the other catalyst in the laboratory-scale reactor, it is postulated that thermal deactivation, which cannot be detected in the larger system, was responsible for the lower long-term activities.

Several commercial silicas were used to support metallocene active centres, and the resulting precatalysts were used to study the impact of the pore size and pore size distribution of the support on the polymerization kinetics and resulting polymer properties. Pore volume distribution played a major role in the fragmentation of silica‐supported catalysts, where mesoporous silicas with a narrow distribution in the region obtained higher activities and faster fragmentation than silicas with a broad pore volume distribution. Therefore, it is shown that care must be taken when using standard information on particle porosity, as this quantity can be misleading. It appears that the minimum pore size, particularly on the particle surface, can be a very important parameter even if it does not impact the estimate of the porosity.