Partial oxidation

About: Partial oxidation is a research topic. Over the lifetime, 8261 publications have been published within this topic receiving 205069 citations.

New catalytic routes for syngas and hydrogen production

Abstract: This review summarizes different catalytic options for the production of syngas and hydrogen starting from simple hydrogen-containing molecules. Particular attention is given to new direct catalytic alternatives in natural gas conversion. Improvements in syngas technology are discussed, including partial oxidation, autothermal reforming, combined reforming and carbon dioxide reforming, and the energy efficiencies of direct and indirect methane conversion are compared. Processes, issues and practical difficulties are discussed with academic and applied efforts presented in parallel. It is emphasized that most of the ongoing research related to the direct processes is at the exploratory stage while technology utilizing indirect approach has advanced to semi-works and initial commercialization plants. The new emerging processes based on partial oxidation features are unique for syngas generation. Further enhancement of such processes plus improvements in other second generation technologies and advances in direct processes are anticipated to provide additional, new attractive paths to the chemical conversion of natural gas. Similarly, on board generation of hydrogen-rich gaseous fuels either for spark ignition engines or for coupled-fuel-cells electric engines is discussed within the scope of both partial oxidation and catalytic decomposition of methanol. A concept based in the thermochemical water splitting, which provides a renewable portable fuel from water in the form of H2, is also presented. Above all, as the chemistry involved in most of these catalytic alternatives takes place under extreme conditions, highly stable catalysts and engineering concepts are being developed.

Cobalt oxide surface chemistry: The interaction of CoO(1 0 0), Co3O4(1 1 0) and Co3O4(1 1 1) with oxygen and water

Abstract: Cobalt oxides comprise two readily accessible cation oxidation states: Co 2+ and Co 3+ , which are thermodynamically competitive under common ambient conditions, and redox mechanisms connecting the two states are largely responsible for their success in partial oxidation catalysis. In our studies, CoO(1 0 0), Co 3 O 4 (1 1 0), and Co 3 O 4 (1 1 1) single crystal substrates have been investigated with X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and low energy electron diffraction (LEED) for their surface reactivity toward O 2 and H 2 O and for their stability under reducing UHV conditions. There is facile inter-conversion between CoO and Co 3 O 4 stoichiometry at the oxide surface which, despite the compositional variability, remains well ordered in long-range structure. Surface impurities, however, can pin the surface at either CoO or Co 3 O 4 compositional extremes. Contrary to reports of a pressure gap that creates difficulty in oxide hydroxylation under UHV, it is pos sible to hydroxylate both cobalt monoxide and spinel oxide substrates with H 2 O, provided sufficient activation is available to dis sociate the water molecule.

Onboard fuel conversion for hydrogen-fuel-cell-driven vehicles

Abstract: Increasingly stringent legislation controls emissions from internal combustion engines to the point where alternative power sources for vehicles are necessary. The hydrogen fuel cell is one promising option, but the nature of the gas is such that the conversion of other fuels to hydrogen on board the vehicle is necessary. The conversion of methanol, methane, propane, and octane to hydrogen is reviewed. A combination of oxidation and steam reforming (indirect partial oxidation) or direct partial oxidation are the most promising processes. Indirect partial oxidation involves combustion of part of the fuel to produce sufficient heat to drive the endothermic steam reforming reaction. Direct partial oxidation is favored only at high temperatures and short residence times but is highly selective. However, indirect partial oxidation is shown to be the preferred process for all fuels. The product gases can be taken through a water–gas shift reactor, but still retain ∼2% carbon monoxide, which poisons fuel-cell ca...

Raman spectroscopy of molybdenum oxides

Abstract: A special sample was prepared by controlled oxidation of MoO2, which contained MoO2, Mo4O11 and MoO3, in order to extend the knowledge about the resonance Raman effect in reduced molybdenum oxides from those close to MoO3 to those close to MoO2. This knowledge is of paramount importance because technical partial oxidation catalysts often contain intermediate Mo oxides of the Magneli type, e.g. Mo4O11, or Mo5O14. The Raman spectra of orthorhombic Mo4O11 and MoO2 have been identified in a Raman microspectroscopic image of 100 single spectra recorded of a mixture of MoO3, MoO2 and Mo4O11. A resonance Raman effect was proven to be responsible for the detection of the molybdenum oxide phases Mo4O11 and MoO2 in dilution with BN when excited at a laser wavelength of 632.8 nm by comparison with Raman microspectroscopic images of the identical sample when excited at 532 nm. The resonance Raman detection of reduced molybdenum oxide phases is discussed in the above mentioned context of their active role in catalytic partial oxidation reactions.