## 3 Results and Discussion
### Analysis of Gaseous Products  
The distribution of syngas content is depicted in Figures 3 and 4. The syngas mainly comprises H\({}_{2}\), CO, CH\({}_{4}\), and CO\({}_{2}\). With the increase in gasification temperature, the CO and H\({}_{2}\) concentrations increase gradually, while the CH\({}_{4}\) and CO\({}_{2}\) concentrations decrease. The percentages of CO and H\({}_{2}\) increase from 17.2% and 7.9% to 48.7% and 16.9%, respectively. Conversely, the percentages of CO\({}_{2}\) and CH\({}_{4}\) decrease from 55.55% and 15.37% to 28.6% and 5.8% (Figure 3b). The Boudouard reaction (6) is limited when the gasification temperature is low. CO\({}_{2}\) dominates syngas. The higher temperature will facilitate this reaction, increasing the content of CO. Additionally, a higher temperature promotes the expansion of the pore structure of biochar, increasing CO\({}_{2}\) reactivity with char and promoting CO production. The methane reforming reaction (10) decreases the CH\({}_{4}\) concentration and increases the H\({}_{2}\) concentration. In addition, CO\({}_{2}\) could react with the tar produced, as shown in Equation (11), promoting its cracking to yield H\({}_{2}\) and CO. Moreover, the tar can be directly fractured to release H\({}_{2}\), as shown in (12). Figure 4: Main gas components obtained from oak MG (**a**) and EG (**b**) at different temperatures. Figure 3: Main gas components obtained from corn stalk MG (**a**) and EG (**b**) at different temperatures. Figure 4a shows the syngas components from corn stalk MG. As the gasification temperature increases from 600 to 1000 \({}^{\circ}\)C, the volume fraction of CO increases from 27.3% to 61.8%, while that of CO\({}_{2}\) decreases from 47.8% to 21.9%. The syngas content of EG is shown in Figure 4b. The volume fraction of CO increases from 27.9% to 50.8%, while the volume fraction of CO\({}_{2}\) decreases from 55.1% to 23.3%. MG produces more CO than EG at the same temperature. Char particles can absorb the microwave energy, resulting in a higher temperature than the surroundings during MG [36]. Under the same heating conditions and temperature, the gaseous products of corn stalk gasification contain less CO\({}_{2}\) than those of oak gasification. Oak is a hardwood, and the specific surface area and pore volume of oak char are lower than those of corn stalk char. The porous structure of the materials promotes the char self-gasification reaction. The net calorific value of syngas is calculated from the relative content of syngas through Equation (5). As shown in Figure 5, the net calorific value of syngas increases with temperature. At 1000 \({}^{\circ}\)C, the highest net calorific values of syngas derived from oak gasification are 10.60 and 9.45 MJ m\({}^{-3}\) (Figure 5a), while the highest net calorific values of syngas generated from corn stalk gasification are 11.61 and 10.06 MJ m\({}^{-3}\) (Figure 5b). As the gasification temperature increases, the content of CO and H\({}_{2}\) in the syngas components gradually increases. The net calorific value of syngas generated from MG is higher than that from EG at the same temperature. \[Q_{L}=10.8v(\mathrm{H}_{2})+12.64v(\mathrm{CO})+35.82v(\mathrm{CH}_{4}) \tag{13}\]  
Carbon conversion (\(\eta_{\mathrm{c}}\), %), which is defined as the percentage of carbon in biomass converted into carbon in the gaseous fuel, is employed to characterize biomass conversion in reaction activity under CO\({}_{2}\) gasification. Where \(G_{\mathrm{g}}\) is the volume of the produced gas (dry basis) per unit mass of biomass (standard condition), C% represents the mass fraction of carbon in the chemical composition of biomass, and CO, CO\({}_{2}\), and CH\({}_{4}\) are the molar fractions of the product gases. \(A_{\mathrm{c}}\) denotes the atomic weight of carbon (12 g mol\({}^{-1}\)), and \(V_{\mathrm{m}}\) represents the molar volume at standard conditions (22.4 L mol\({}^{-1}\)). Table 4 shows the carbon conversion from feedstock.