Oxidative Dehydrogenation of Ethane: A Chemical Looping Approach

Abstract

The current study investigates a chemical‐looping‐based oxidative dehydrogenation (CL‐ODH) concept for ethane‐to‐ethylene conversion. In this cyclic redox scheme, an oxide‐based redox catalyst is used to selectively combust hydrogen from ethane dehydrogenation. As the hydrogen product limits ethane conversion, in situ oxidation of hydrogen enhances the ethane conversion and ethylene yield. Moreover, heat required in ODH is compensated by re‐oxidation of the oxygen‐deprived redox catalyst, enabling auto‐thermal operation for the overall process. Compared to steam cracking, CL‐ODH can potentially achieve higher efficiency with lower CO2 and NOx emissions. Silica and magnesia‐supported manganese oxides are investigated. It is determined that unpromoted Mn/SiO2 and Mn/MgO redox catalysts exhibit low selectivity towards ethylene. The addition of promoters such as sodium and tungsten renders effective redox catalysts with satisfactory activity, selectivity, oxygen carrying capacity, and redox stability.

Oxidative dehydrogenation of ethane under a cyclic redox scheme – Process simulations and analysis

“…The major difference from steam cracking is the absence of the energy-intensive furnaces, which are replaced by a reactor-regenerator configuration. The hydrocarbon and CO x yields used in the current work are based upon experimental results of an alkali doped Mn-Mg oxide similar to that reported in previous work [17,18]. As this system involves mixed oxides [18] that are not available in the ASPEN Plus ® database, the system is simplified to a MgO supported MnO x .…”

“…The hydrocarbon and CO x yields used in the current work are based upon experimental results of an alkali doped Mn-Mg oxide similar to that reported in previous work [17,18]. As this system involves mixed oxides [18] that are not available in the ASPEN Plus ® database, the system is simplified to a MgO supported MnO x . Mn 3 O 4 (Mn at 8/3 þ average valence state) is used as the simulated oxygen carrier phase, which donates its lattice oxygen during the ODH reaction.…”

“…The carbon yields for the various processes are listed in Table 2. These are based on the experimental results as given in previous work [17,18]. Although small amount of CO x from coke burning can be observed during redox catalyst regeneration, the yield is negligible, and is thus excluded from the simulation.…”

“…In a previous work, we have reported a highly effective, alkali doped MnO x -MgO redox catalyst for the abovementioned CL-ODH scheme [17,18]. High ethane conversion and ethylene selectivity as well as satisfactory redox stability and oxygen carrying capacity are achieved using such a redox catalyst.…”

Enhancing the capacity of oxygen carriers for selective oxidations through phase cooperation: bismuth oxide and ceria–zirconia

“…In the light of these advantages, interest in chemical looping as a technology for the production of chemicals has been gradually increasing. [13][14][15][16][17][18] An important example of a semi-commercial application of this technology is Dupont's process for oxidising n-butane to maleic anhydride, undertaken in a circulating fluidised bed (CFB). 4 Although this process has seen significant improvement since its conception in the 1980s, 19 vanadium pyrophosphate is still used as the oxygen carrier and suffers from a low oxygen-carrying capacity, of the order of 0.2 wt% (kg O/kg carrier).…”