(413f) Converting Biogas to Liquid Fuels By Low Energy Electrical Corona Discharge Processes

Converting Biogas to Liquid Fuels by
Low Energy Electrical Corona Discharge Processes

Yu Miao, Ian Reddick, Adam Shareghi, Andrew Traverso, Nicolas
AuYeung, Annette von Jouanne, Goran Jovanovic, Alexandre Yokochi

Biogas is considered as a
renewable resource.  Though abundant sources are available worldwide, such as
dairies, piggeries, landfills, etc., it is usually disposed by flaring because
of its low economic value. The development of technologies to use biogas as
feedstock to produce liquid fuels like gasoline or diesel therefore would have a
positive economic and environmental impact, and stimulate new approaches in
industrial chemistry.

In this work, a new process that
enables high efficiency conversion of biogas to liquid transportation fuels has
been developed. The approach is to employ low energy electron impact ionization
through the use of a non-thermal plasma generated by an atmospheric pressure
electric corona discharge. Additionally, microtechnology has been combined with
this corona discharge technology. The key advantages of chemical
microtechnologies of: (1) the use of components and structures on the
microscale creates strong gradients with respect to temperature, concentration,
pressure, and reactive species; (2) the efficient heat and energy management
results in a stabilization of the corona discharge and contributes to
maintaining the non-thermal properties of plasmas [1].

In pour process, because we use of a non-thermal corona discharge process
that does not require high temperatures for the conversion intended, a natural decrease
of energy losses is found, since no process heat is required to effect the
conversion. Non-thermal corona discharges are generally characterized by low
gas temperatures, but high electron temperatures, with high concentrations of
free electrons (up to a density of 10¹⁹ m^-3) [2]. In
order to develop cold plasmas it is essential that the “heavy” particles (i.e.,
ionized gas) are not excited, as it is collisions between heavy particles that
lead to high temperatures; inelastic collisions between electrons and heavy
particles induce the plasma chemistry.  

Both single-discharge and
multi-discharge reactors have been built, and their performance proves the
concept of chemical conversion of biogas and demonstrates the ability to
produce long-chain hydrocarbons. In order to identify which parameters are most
important in the optimization of the conversion process, the experimental
design has been developed as a guide for experimental work. Major parameters
under investigation include the power level per discharge, the discharge gap,
the reactive gas flow rate, the synthetic biogas composition, the concentration
of inert, and the gas pressure. A high energy efficiency up to 85% can be
achieved, and methane conversion can reach up to 25% with high selectivity
(80~90%) towards C2+ hydrocarbons.

Reference:

[1] D. Mariotti, R. M. Sankaran
(2010), “Microplasmas for nanomaterials synthesis,” Journal of Physics D:
Applied Physics, 43 (32), pp. 323001.

 [2] C. Tendero, C. Tixier, P.
Tristant, J. Desmainson, P. Leprince (2006), “Atmospheric Pressure Plasmas: A
Review,” Spectrochimica Acta B, 61, pp. 2-30.