Abstract
•Hydrogen production by methanol sono-pyrolysis was computationally analyzed.•An accurate model was developed for H2 production from methanol sono-conversion.•Hydrogen yields were substantially increased with methanol addition at low dosage.•Hydrogen yielding and CH3OH conversion decreased with frequency increase.•The H2 yield is ideal at an acoustic intensity of 1 W/cm2 and liquid temp. of 20-30 °C.
A comprehensive numerical investigation was conducted to analyze the effect of ultrasound frequency (213-1000 kHz), ultrasonic intensity (0.7-1.5 W/cm²) and medium temperature (293.15-333.15 K) on the production of hydrogen from methanol decomposition inside acoustic bubbles (methanol sono-conversion). The adopted model was firstly compared with some reference data. It was found that in the absence of methanol (in the presence of methanol), the bubble temperature, hydrogen production (and methanol conversion) are decreased monotonously with an increase in frequency. The maximal bubble temperature is slightly impacted by the presence of methanol under ultrasonic frequencies that are equal to or greater than 515 kHz. In addition, the yield of H2 is larger in the presence of methanol, regardless of the utilized frequency. Between 213 to 355 kHz, methanol conversion and hydrogen production are most efficient. Both H2 production and CH3OH degradation are accelerated under an ideal acoustic intensity of 1 W/cm2. At a liquid temperature of 303.15 K, a turning point in bubble temperature may be noticed in the absence of methanol, and at a liquid temperature of 323.15 K, the highest hydrogen production can be achieved. Hydrogen production and methanol conversion are most efficient at liquid temperatures between 293.15 and 303.15 K.
Graphical Abstract
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