The partial oxidation of methane to ethylene/ethane and to methanol/formaldehyde is being investigated in a novel gas recycle reactor-separator. The units will employ a fixed-bed catalytic or electrocatalytic reactor with an optimized catalyst composition and an optimally designed swing-bed molecular sieve trap. The project is expected to demonstrate the technical feasibility of scale-up of the novel reactor-separator for the one-step oxidative coupling or partial oxidation of methane.
The development of direct (one-step) and energy efficient process for the conversion of methane to ethylene and to methanol/formaldehyde has been a long-sought goal. Despite intensive research during the last twelve years, the maximum ethylene and formaldehyde yields obtained in laboratory-scale reactors until 1994 was of the order of 20% and 5% respectively.
In 1994, one of the participating research teams (University of Patras) developed a novel laboratory scale gas-recycle reactor separator which gave ethylene yields up to 85% for the oxidative coupling of methane (OCM)(Science 254, 1583, 1994). In this novel reactor-separator ethylene and ethane are trapped, and thus protected from further oxidation, in a molecular sieve trap in the recycle loop. They are released by subsequent heating of the molecular sieve trap. The above very encouraging results were obtained in a small microreactor (catalyst mass 0.1g, molecular sieve mass 2-3g) able to handle up to 3 ccSTP/min of CH4.
The current objectives are:
1. To study the scale-up of the novel reactor-separator for ethylene production by building bench-scale units able to convert up to 1000 ccSTP/min of CH4 each to ethylene.
2. To construct and test a similar catalytic reactor-separator for the production of methanol/formaldehyde from methane (up to 1000 ccSTP/min).
Efficient state-of-the-art catalysts and molecular trapping materials are already being produced and tested by the project team and preliminary results have already shown a five-fold enhancement in formaldehyde yield relative to single-pass conditions using the novel-reactor separator concept.
Expected Achievements and Exploitation
The outputs of this project are:
- Specifications of the optimal catalyst, electrocatalyst and trapping materials for the novel reactor-separator units.
- Design, construction and operation of prototype reactor-separator units at flowrates on the order of 1 l/min.
The results will provide a firm technical basis for assessing the feasibility for developing new industrial processes for the one-step energy-efficient conversion of methane to ethylene and formaldehyde.
Funding SchemeCSC - Cost-sharing contracts
SW7 2AZ London
15125 Amaroussio - Athens
1003 AA Amsterdam
CB2 1EW Cambridge