Nonthermal Influence of Microwave Power on Chemical Reactions

Abstract

To clarify the effect of microwave irradiation on acceleration of chemical reactions other than heating, Arrhenius' plots were taken for the disintegration reaction of sodium hydrogen carbonate water solution. Then to observe the influence of microwave field on the reaction, gas-generating velocities with different irradiated microwave powers were measured under a constant temperature condition. As a result, it was recognized that the microwave field acts to decrease the activation energy of the reaction. Next, pulsed and CW microwave powers, both having the same mean power, were applied to the solution and the pulsed microwave field was observed to accelerate disintegration more than CW. Although the molecular mechanism is not clear, a decrease of the activation energy seems to accelerate the reaction.

Applications of microwave dielectric heating in environment-related heterogeneous gas-phase catalytic systems

“…In some early studies of microwave-assisted catalysis results were obtained which were difficult to explain in terms of non-uniform heating of the catalyst and it was suggested that microwave irradiation might interact directly with the reactants to cause an enhancement of the reaction rate [105][106][107]. However, further studies, both theoretical and experimental, have conclusively demonstrated that specific athermal effects are implausible [22,[108][109][110].…”

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“…In the early studies on microwave-assisted catalysis, the results that could not be explained solely as a consequence of simple thermal heating led to the suggestions of a non-thermal microwave-specific effect [7][8][9]. However, further studies both theoretically and experimentally have conclusively demonstrated that the specific athermal effects are implausible.…”

The Effects of Microwave Heating on the Isothermal Kinetics of Chemicals Reactions and Physicochemical Processes

“…Booske et al, 1997, used the existence of non-thermal energy distributions to explain microwave-enhanced solid-state transport. Based on the experimentally confirmed decrease in the values of the activation energy of sodium bicarbonate decomposition under microwave reaction conditions, Shibata et al, 1996, concluded that the effect of a microwave field on dielectric materials is to induce rapid rotation of the polarized dipoles in the molecules. This generates heat due to friction while simultaneously increasing the probability of contact between the molecules, thus enhancing the reaction rate and reducing the activation energy.…”