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The selective hydrogenation of benzoic acid to benzaldehyde on ZrO2 and Cr2O3–ZrO2 at 523 K was studied by IR spectroscopy. An enhancement of the hydrogenation rate of benzoic acid by Cr2O3 doping to ZrO2 was observed. The main role of Cr2O3 was considered to be the step of activating hydrogen. An intermediate species was observed based on the IR bands during a transformation from the adsorbed benzaldehyde to the benzoate at lower temperatures. This is discussed in conjunction with the reaction mechanism of the hydrogenation. The intermediate species was regarded as being the chemisorbed benzaldehyde by an analysis of the observed IR bands.

The present work is concerned with the real time in situ visualization of crystallization processes inside strongly supercooled silicate melts using optical projection technique. The crystallization experiments are carried out for forsterite composition under container-less conditions. Starting material is heated above its liquidus temperature (2169 K) using a high power CO2 laser and crystallization is initiated following rapid cooling. Three different values of supercooling (ΔT≈320, 400, and 500 K, calculated with respect to the liquidus temperature of forsterite composition as reference) are independently employed to initiate the nucleation process by adjusting the output power of CO2 laser. Primary findings of the study show that a suitably designed optical system is capable of imaging melt convection at temperatures as high as near liquidus and presents a novel approach for the prediction of resultant crystallization textures in real time nondestructively. Using the developed optical arrangement, formation of porphyritic-like textures and parallel-barred structures could be successfully visualized during the crystallization process. The results also reveal that for very large values of supercooling, it is possible to initiate nucleation from inside the melt droplet. The in situ predictions of resultant crystalline textures are compared with the textures revealed by photomicrographs of the corresponding thin sections and a good agreement is seen between the two observations.