Catalytic reactions of coke with dioxygen and steam over alkaline-earth-metal-doped cerium-zirconium mixed oxides

Gasification of Radical Coke with Steam and Steam–Hydrogen Mixtures over Manganese–Chromium Oxides

“…Proposed Mechanism for Coke Gasification with Mn−Cr−O Catalysts. Based upon our experimental results and previously proposed mechanisms for steam coke gasification in the presence and absence of catalysts, 27,51,67,68 the following (stoichiometric, nonelementary) reactions are expected to occur on the coke-catalyst surface…”

“…Based upon our experimental results and previously proposed mechanisms for steam coke gasification in the presence and absence of catalysts, ,,, the following (stoichiometric, nonelementary) reactions are expected to occur on the coke-catalyst surface where M x O y /M x O y +1 represents a metal oxide species that can undergo redox cycles and provide oxygen to remove the coke. In the absence of a redox catalyst, coke gasification with H 2 O mainly depends on eqs and , where H 2 O reacts with the carbon surface to form CO and H 2 .…”

“…Nevertheless, there are several similarities between the performance of these catalysts and other catalytic coke gasification reactions on carbon-covered catalyst surfaces. In general, alkali or alkaline earth metals have been extensively reported as some of the most active catalysts or promoters for coke gasification. ,, However, the addition of Mn/MnO x has also led to an improvement in many catalysts’ activities. Our previous work showed that Mn doped ceria-alumina catalysts (containing Mn 3 O 4 species) substantially increased the steam gasification rate constant for industrial coke .…”

“…In this study, we provide insight into the coke gasification activity of several Mn–Cr–O spinel oxides containing different Mn/Cr ratios, single oxides of Mn and Cr, and α-Al 2 O 3 for comparison. Using our previously reported methods of depositing radical coke in situ onto metal oxides coupled with subsequent thermogravimetric analyses, − we evaluate the activity of the various catalysts for coke gasification with steam. Additionally, since hydrogen is a significant product in the cracking process, the coke gasification activity of catalysts was further studied under steam–hydrogen mixtures.…”

Synthesis, Structural and Magnetic Properties of Manganese Substituted Magnesium Chromite.

“…The interest in these oxides emerges from their versatile applicability in telecommunication, power transformers, audio and video and many other applications involving electrical signals. Oxides spinel have been extensively studied by several workers [1][2][3] in order to elucidates the relationship between structure, bonding and magnetic properties because of technological potential of these materials. The benefit found in the oxides due to their structural and chemical variations on a nano scale, which are important for developing optimal magnetic properties [4][5][6].…”