微波加热与常规加热方式下甲苯的裂解实验研究

为了减少生物质焦油含量,探索达到最优焦油脱除效果的操作条件,在固定床反应器上,考察了微波加热(MH)与常规加热(EH)方式下温度、反应气氛、停留时间对焦油模型化合物甲苯裂解的影响及气固产物特性。实验结果表明,甲苯转化率随裂解温度升高而升高;700℃下N2、水蒸气、CO2气氛下微波加热甲苯转化率为92.7%、97.8%、93.9%,常规加热条件下为59.2%、59.7%、59.4%;停留时间对甲苯裂解影响较小。甲苯裂解主要气体产物为H2,两种加热方式下H2选择性有较大差异,600℃~800℃微波加热比常规加热均高出约15%。甲苯裂解的主要固体产物为碳,常规加热下均为无定型裂解碳,微波加热下有少数特殊碳形态生成,电镜扫描发现为碳纳米管。另外,生物质焦的XRD分析表明,微波加热裂解甲苯的过程中存在"热点效应"。

Decomposition of toluene with microwave heating and electrical heating

The decomposition of toluene over a biomass char packed bed was studied with microwave heating(MH) and electrical heating(EH). The effects of temperature, atmosphere and retention time on the decomposition behavior and the product properrties of gas and solid were investigated. The results show that the toluene decomposition rate increases with the increase of temperature in the range of 600℃～800℃. At 700℃, the conversion of toluene is 92.7%, 97.8% and 93.9% in N₂, steam and CO₂ atmospheres, respectively with MH, while the conversion of toluene with EH is 59.2%, 59.7% and 59.4%, respectively. The retention time has a slight effect on the toluene conversion. The selectivity of the product H₂ strongly depends on the heating method. The selectivity of H₂ under MH is about 15% higher than that under EH. Nanofibers are formed on the surface of the char under MH, while only amorphous carbon is found on the char under EH. XRD analysis of biomass char implies that the hot spots effect may take place under MH.