A single-point optical probe is developed that can accurately obtain local gas holdup in a gas−liquid stirred tank across a wide range of operating pressures, temperatures, and fluids. It is found that the probe orientation to the flow in a stirred tank can cause underestimations in gas holdup if only a single probe orientation is used. The probe is also able to capture the complex flow pattern in the vessel. This allows improved understanding of optical probes and stirred tanks and generation of data at elevated pressure and temperature conditions needed for development of new fundamental models.

A fiber-optic probe is developed for the fast, in-situ measurement of volumetric expansion of multiphase and multicomponent systems. An experiment with the binary mixtures of CO 2 -toluene and CO 2 -ethanol was conducted to demonstrate the usefulness of the fiber-optic probe in accurately tracking the isothermal volumetric expansion as a function of pressure. In the 1-L autoclave that has been used, the probe was shown to detect the liquid level height within a precision of 0.35% of the total height of the vessel. The results for the volumetric expansion of toluene and ethanol with CO 2 correlate well with those found in the literature. The probe itself can be used up to pressures of 140 barg and temperatures of 120°C.

Potassium-promoted, oxide-supported PdAu is catalytically active for the gas-phase acetoxylation of ethylene to form vinyl acetate monomer (VAM), in which the potassium improves long-term activity and VAM selectivity. The alkali...

Pt-Re supported on Ce 0.52 Zr 0.48 O 2 was studied for the carbon dioxide reforming of methane at 800°C. Diffuse reflectance fourier transform infrared spectroscopy and temperature programmed reduction studies suggest that Pt and Re segregation occurs during the reaction. The segregation results in an increase in the Pt sites available for CH 4 decomposition and results in the bimetallic catalyst exhibiting an increase in the conversion of methane with time on stream. After 20 h of reaction, the CH 4 conversion observed for the bimetallic catalyst was the same as the CH 4 conversion observed for the monometallic catalyst.

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