Search for: All records

The kinetic behavior of CrO_xsites supported on Fe doped CeO₂was studied for CO₂-assisted propane oxidative dehydrogenation. 

Propane oxidative dehydrogenation (ODH) in the presence of CO 2 was investigated over a series of Fe-doped CeO 2 catalysts. The well-recognized properties of cerium oxide materials regarding improved oxygen mobility and oxygen storage capacity (OSC) were utilized towards the synthesis of stable catalytic systems. The iron–cerium oxide solid solution catalysts with an Fe dopant content from 1% up to 15% were successfully synthesized via a co-precipitation method and calcined at 873 K. It was confirmed by XRD and Raman characterization that all samples featured a single cerianite crystalline phase with periodic lattice Ce ions substituted by Fe ions, with no hematite phase identified. Initial screening of catalytic behavior showed that the propane ODH pathway was enhanced at high Fe/Ce ratio while propane cracking was suppressed. Stable propane conversion and propylene selectivity for up to 20 hours were achieved for the synthesized catalysts with moderate Fe loading. Ex situ Raman, XPS and STEM were applied to analyze post-reaction catalysts and confirmed that deactivation occurring over low Fe catalysts resulted from coke deposition on the surface, while CeO 2 sintering and Fe migration to form nanocrystals were the primary deactivation reasons for high Fe loading catalysts. 

An in situ Raman spectroscopic kinetic study of the glucose mutarotation reaction is presented herein. The effect of metal chlorides on the ease of the ring opening process is discussed. It is shown that SnCl 4 facilitates the mutarotation process towards the β-anomer extremely fast, while CrCl 3 appears to promote the formation of the α-anomer of glucose. The infrared spectra of humins prepared in different Lewis acids underscore the possibility of multiple reaction pathways.