Production of hydrogen in a conventional microwave oven

Abstract

Hydrogen is produced by generating in-liquid plasma in a conventional microwave oven. A receiving antenna unit consisting of seven copper rods is placed at the bottom of the reactor furnace in the microwave oven. 2.45 GHz microwave in-liquid plasma can be generated at the tips of the electrodes in the microwave oven. When the n-dodecane is decomposed by plasma, 74% pure hydrogen gas can be achieved with this device. The hydrogen generation efficiency for a 750 W magnetron output is estimated to be approximately 56% of that of the electrolysis of water. Also, in this process up to 4 mg/s of solid carbon can be produced at the same time. The present process enables simultaneous production of hydrogen gas and the carbide in the hydrocarbon liquid.

Converting a Microwave Oven into a Plasma Reactor: A Review

“…In brief, the claims are as follows: (1) positioning a vacuum chamber within the MRC with embodiments for admitting gas into the vacuum chamber and through the cavity and for extracting gas by-products from the vacuum chamber; (2) relating to claim 1, where a means of regulating the gas to generate uniform plasma in the vacuum chamber; (3) a moving antenna for a means of generating a time average of uniform plasma; (4) a rotating antenna for a means of generating a time average of uniform plasma; (5) a means of reducing microwave leakage around each feedthrough; (6) a means of water cooling substrates within the vacuum chamber during plasma etching without thermal damage to the substrate during the plasma etch process; (7) relating to claim 6, where the water tubes have a heat transfer relationship with the vacuum chamber with a means of microwave leakage prevention; (8) a means of controlling microwave power; (9) relating to claim 8, a potentiometer in series with the primary transfer side of the magnetron transformer for controlling the maximum power in the oven; (10) relating to claim 9, when plasma etching of organics from substrate; and finally, (11) relating to claim 10, the use of water cooling of the substrate. Beyond Ribner's patent, some studies [11][12][13][14][15][16][17][18][19][20][21][22] show that the microwave oven plasma reactor can be used for a multitude of processes and in many levels of oven reconstruction. e following sections describe the changes required to conventional domestic microwave ovens that range from minimal to major.…”

“…Microwave in-liquid plasma decomposition of n-dodecane (molecular formula: C 12 H 26 (I)) to simultaneously produce hydrogen gas and carbide in the hydrocarbon liquid has been achieved using a converted microwave oven at a reported microwave power level of 500 to 750 W [18][19][20]. A typical representation of these reactors is shown in Figure 2.…”

“…First, consider the single-tip electrodes [18][19][20]. ese metal electrodes have a dimensional length of L � 21 mm and a diameter of 1.5 mm, and they are fixed vertically in a single array (Figure 3(a)) or in a multiple array (Figure 3(b)) with 1 electrode in the center and up to 6 electrodes circumferentially spaced at a gap separation of λ m /4, where λ m is the wavelength of the microwave radiation passing through the medium.…”

“…Based on the works [18][19][20] and the work of Pongsopon et al [21], it is generally considered that the electrodes have three well-defined roles: to confine the plasma to the immediate proximity of the electrode(s) tip, to function as a catalytic source for plasma heterogeneous reaction, and in the case of manufacturing carbon nanomaterials, to provide a substrate on which the carbon material can grow. In the first of these roles, increasing the number of electrodes from 1 to 6 has revealed that the efficiency of plasma decomposition of n-dodecane does increase, but beyond 6-7 electrodes, the reaction efficiency becomes rate-limited.…”

“…Once the first conversion of a microwave oven into a plasma reactor was reported in 1978 [10], plasma-induced synthesis of inorganic compounds became available [11][12][13], followed by plasma modification of polymer surfaces [14]. Interest in the conversion of microwave oven for plasma processing has also been reported for plasma pyrolysis paper [15,16] and in-liquid plasma decomposition to produce hydrogen gas and carbon films [17][18][19][20][21]. More recently, initial studies of marine diesel exhaust gas abatement within a converted microwave oven have been reported [22]; however, little gasline, or reactor conversion, details were given.…”