Catalytic Oligomerization of Methane via Microwave Heating

Abstract

Catalytic microwave heating has been used as a method for the oligomerization of methane to higher hydrocarbons. Many catalysts were tested in this reaction. Nickel powder, iron powder, and activated carbon were the most active and efficient catalysts for the production of higher hydrocarbons. When helium was used as a diluent gas and the applied power was optimized, the selectivities were controlled to the most desired products. Iron powder was active only at high power (1130 W). At these conditions acetylene was avoided and ethylene and ethane were produced in the same proportion. At low power (378 W) with nickel powder as catalyst and no diluent, ethane was the major C 2 hydrocarbon. The amount of acetylene increased when arcing was observed. The proportion of C 2 products changed from ethane > ethylene > acetylene to ethylene > acetylene > ethane when the power was increased from 378 to 1130 W. The major product was CO when high power (1130 W) was used. Selectivities toward C 3s and C 4s were enhanced to 16 and 18%, respectively, and the major products were propane and methylpropane when He was used as a diluent gas. Activated carbon catalysts and helium diluent led to a product distribution of C 2s of ethylene > acetylene > ethane at low applied power (378 W). At medium power (754 W) as time increases, the selectivities to C 2s decrease and the selectivity to benzene increases to 33%. Some manganese oxides such as OMS-1, OMS-2, and MnO 2 (dielectric constant, ≈ 10 4 ) were not active in these reactions. These data suggest that the dielectric constant is not the most important factor in the oligomerization of methane via microwave heating. Conversion and activities of these materials are not proportionally related to the surface area of the catalysts.

Oxidative coupling of methane using microwave dielectric heating

“…The results observed are in agreement with the results obtained by Marun et al [21], Suib and Zerger [22] and Suib [23]. In the oligomerization of methane to higher hydrocarbons carried out by Marun et al using microwave heating, their results showed arc formation and discharges produced by the catalyst.…”

Microwave assisted heterogeneous catalysis: effects of varying oxygen concentrations on the oxidative coupling of methane

“…The results obtained are in line with that observed by other researchers [18][19][20][21]. In the study by Marun et al [18,19] on the oligomerization of methane to higher hydrocarbons using microwave heating, they observed both arc formation and discharges produced by the catalyst.…”

“…In the study by Marun et al [18,19] on the oligomerization of methane to higher hydrocarbons using microwave heating, they observed both arc formation and discharges produced by the catalyst. Ethane was found to be the major product at the beginning of the reaction.…”

Methane conversion using a high‐frequency pulsed plasma: Discharge features

“…AC and DC corona discharges, dielectric-barrier discharge, arc plasma, and the combination of microwave plasma and catalysts have been reported to produce acetylene, ethylene, hydrogen, methanol, and other liquid products (Wan, 1986;Mallinson et al, 1987;Bhatnagar and Mallinson, 1995;Liu et al, 1996;Thanyachotpaiboon et al, 1998;Onoe et al, 1997;Okumoto et al, 1998;Suib and Zerger, 1993;Marun et al, 1999;Eliasson et al, 2000;Yao et al, 2000d). Recently, methane reforming with CO, using plasmas, which may contribute to effective utilization of methane and reduction of greenhouse gas CO, emission, has been reported (Gesser et al, 1997;Bromberg et al, 1998;Larkin et al, 1998;Zhou et al, 1998;Huang et al, 2000;Yao et al, 2000b).…”