National Changhua University of Education Institutional Repository : Item 987654321/16855
English  |  正體中文  |  简体中文  |  Items with full text/Total items : 6491/11663
Visitors : 24753563      Online Users : 56
RC Version 3.2 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Adv. Search
NCUEIR > College of Science > Department of Chemistry > Books >  Item 987654321/16855

Please use this identifier to cite or link to this item:

Title: Oxidative Dimerization of Methane Over Sodium-Promoted Calcium Oxides
Authors: Lin, Chiu-Hsun;Wang, Ji-Xiang;Jack H. Lunsford
Contributors: 化學系
Date: 1988
Issue Date: 2013-06-05T09:36:53Z
Publisher: Springer US
Abstract: Sodium-promoted calcium oxides are active and selective catalysts for the partial oxidation of methane to ethane and ethylene using molecular oxygen as an oxidant. In a conventional fixed-bed flow reactor, operating at atmospheric pressure, a 45% C2 (sum of ethane and ethylene) selectivity was achieved to a 33% methane conversion over 2.0 g of the catalyst at 725°C with a gas mixture of CH4/O2 = 2. The other products were CO and CO2. EPR results indicate that [Na+O-] centers in Na/CaO are responsible for the catalytic production of CH3 from methane through hydrogen-atom abstraction. These CH3 radicals dimerize, primarily in the gas-phase, to form C2H6 which further oxidizes to C2H4. Increasing temperatures reverse the gas-phase equilibrium CH3+O2 ⇌ CH3O2 to produce more CH3 and increase the C2 selectivity. The CH3O2 eventually is converted to carbon oxides under the reaction conditions employed, therefore increasing O2 pressures decrease the C2 selectivity. There is evidence that CH3O2 in the presence of C2H6 initiates a chain reaction which enhances the methane conversion. The addition of Na to CaO also reduces the surface area of the catalysts, thus minimizing a nonselective oxidation pathway via surface methoxide intermediates.
Relation: 收錄在「Oxygen Complexes and Oxygen Activation by Transition Metals」, Edited by Arthur Earl Martell, Donald T. Sawyer, : 313
Appears in Collections:[Department of Chemistry] Books

Files in This Item:

There are no files associated with this item.

All items in NCUEIR are protected by copyright, with all rights reserved.


DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback