Comparison of Cellulose Decomposition by Microwave Plasma and Radio Frequency Plasma

Abstract

Biomass conversion by plasma has the advantage of mainly producing gaseous products, H2, CO and CO2. Though the thermal plasma has been used for this conversion, the plasma temperature is too high to be unfit for the conversion biomass. The temperature of cold plasma, however, is lower under 3000 K. It expects to be adequate for biomass conversion. Cold plasma can be obtained with irradiation microwave (2.45 GHz) or radio frequency (13.5 MHz) under reduce gas pressure. Therefore, in present study, the effective decomposition of cellulose by microwave plasma (MWP) and radio frequency plasma (RFP) is examined. The conversion of cellulose by MWP (XMWP) is higher than that by RFP (XRFP), irrespective of the reaction time. XMWP and XRFP reach 92.8 wt% at 10 min and 68.1 wt% at 30 min. The maximum yield of gaseous products (Ygas) by MWP is 85.1 wt% at 10 min, higher by 23.2 wt% than Ygas by RFP at 30 min. The amount of H2 and CO obtained by MWP is 18.0 mmol/g and 23.5 mmol/g, it is larger than that obtained by RFP. Comparing the relationship between conversion and yield, Ygas of MWP is slightly higher than that of RFP under X of 60 wt%, and both Ygas is almost same over 60 wt%. The amount of H2 and CO obtained by MWP is larger by 9.3 mmol/g and 9.6 mmol/g than that obtained by RFP. C, H and O element in cellulose is mainly distributed to H2 and CO by MWP. RFP mainly distributes H and O element to the other gases without H2 and CO. In addition, a large amount of C element is remains in the residue. Those results is found that MWP was more suitable for cellulose gasification than RFP, since MWP can highly convert C, H and O element to H2 and CO by higher energy of microwave frequency in comparison with radio frequency

Metastable Patterning of Plasma Nanocomposite Films by Incorporating Cellulose Nanowhiskers

“…The origins of internal stresses may be often attributed to strain mismatch due to thermal heating under plasma or artificial stretching and release or simply a property mismatch. In the present case, we believe that the elevated electron temperatures (flash temperatures) induced by plasma may generally contribute to the surface activation of cellulose, but the effects are smaller on highly crystalline CNWs that are thermally stable up to 200 °C. , Moreover, the eventual high-temperature fraction in low-pressure glow discharge plasma remains small (<1%), but the ion temperatures in the bulk of the cold plasma remain close to room temperature because we used a minimum power of 20 W. It seems that the time for temperature flashes is too short (<1 s) for thermal gradients within the deposited film and the substrate to induce a patterned film morphology over a longer period of time. Also, artificial heating of the nanocomposite film above the glass-transition temperature of the polymer did not remove the buckling pattern due to the reinforcing action of the CNWs.…”

Plasma technology for lignocellulosic biomass conversion toward an electrified biorefinery

“…Finally, Konno et al 207 compared the decomposition of cellulose by MW (2.45 GHz) and RF plasma (13.56 MHz) in an Ar plasma. They concluded that the cellulose conversion and syngas amount in the MW plasma was higher than that in RF that produced other gases.…”

Microwave discharges at low pressures and peculiarities of the processes in strongly non-uniform plasma

“…A comparison of cellulose decomposition by microwave and RF plasma at reduced pressures was fulfilled in [257]. Results suggest that microwave plasma is suitable for cellulose gasification in comparison with RF plasma, since the former highly convert the element of C, H and O to H2 and CO by the higher energy of microwave frequency than that of radio frequency.…”