Industrial Feasiblity of Direct Methane Conversion to Hydrocarbons over Fe-Based Fischer Tropsch Catalyst

Abstract

Recently, as a direct consequence of the dwindling world oil reserves and the growing awareness of the environmental problems associated with the use of coal as energy source, there is growing interest in cheaper, abundant and cleaner burning methane. The Gas-to-Liquid technology offers perhaps the most attractive routes for the exploitation of the world huge and growing natural gas resources. Using this process the erstwhile stranded gas is converted to premium grade liquid fuels and chemicals that are easily transported. However, a widespread application of the GTL process is being hampered by economical and technical challenges. The high cost of synthesis gas, for instance, weighs heavily on the economics and competitiveness of the process limiting its wider application. This work presented a modified Gas-to-Liquid process that eliminates the costly synthesis gas production step. The proposed process utilized an alternative pathway for methane activation via the production of chloromethane derivatives which are then converted to hydrocarbons. It established that hydrocarbons mainly olefins can be economically produced from di-and tri-chloromethanes over a typical iron-based Fischer Tropsch catalysts in a moving bed reactor at industrially relevant conditions. Some of the attractions of the proposed process include a) the elimination of the costly air separation plant requirement b) high process selectivity and c) significant reduction of carbon dioxide emissions thereby saving on feedstock loss and the costly CO 2 removal and isolation processes.

Halogen-Mediated Conversion of Hydrocarbons to Commodities

“…More recently, Rabiu and Yusuf conceived a new process for olefins-rich hydrocarbon synthesis from di-and trichloromethanes over an iron-based Fischer−Tropsch catalyst, Fe/Al 2 O 3 /Cu, operating in a moving bed reactor under the industrially relevant conditions. 388 However, no experimental details were disclosed regarding the activity and selectivity. Besides, the catalysts used were rather fragile in the presence of the chlorine-rich environment.…”

“…This endothermic reaction is thermodynamically favorable and essentially goes to completion at relevant temperatures (573–773 K) over a catalyst such as ZnCl 2 supported on alumina or zeolites. More recently, Rabiu and Yusuf conceived a new process for olefins-rich hydrocarbon synthesis from di- and trichloromethanes over an iron-based Fischer–Tropsch catalyst, Fe/Al 2 O 3 /Cu, operating in a moving bed reactor under the industrially relevant conditions . However, no experimental details were disclosed regarding the activity and selectivity.…”

Methanol on the rocks: green rust transformation promotes the oxidation of methane

“…Furthermore, MeOH serves as a radical scavenger resulting in its own oxidation to formaldehyde (which was detected), formate and CO 2 [40]. The production of organohalogens in the presence of Cl − anions, likely through a radical chlorination pathway [41], adds further evidence to the radical-based hypothesis. In this case, the Cl − radical ion substitutes for the hydroxyl radical to oxidize CH 4 yielding methyl chloride (MC), DCM and TCM, instead of MeOH, which was observed in our experiments.…”