微波辅助生物质焦炭诱导甲苯裂解和重整试验

Toluene Cracking and Reforming over Biomass-derived Char under Microwave Heating

选用甲苯模拟焦油芳香环物质,研究微波辅助生物质焦炭诱导甲苯裂解和重整反应规律、产物特性和焦炭变化。试验结果表明,焦炭对甲苯裂解有催化作用,微波环境易于甲苯裂解。甲苯裂解率和氢气选择性与温度正相关,750℃是适宜的温度选项,此温度下裂解率与氢气选择性分别为92.77%和91.94%,此后无明显变化。通入CO2促使甲苯重整制备合成气,700℃最高转化率92.03%和最大合成气收率91.30%均在CO2流量为80 m L/min时实现,H2/CO值随CO2流量的加大而降低直至0.22。通入CO2导致焦炭碳质量变化率增加,700℃最高达5.42%,此部分碳转化合成气,对合成气产率的贡献率最高可达15.40%。通入CO2可减缓积碳对甲苯转化的不利影响。

From the point of developing a new approach for the disposal of tar derived from biomass gasification,microwave-assisted tar cracking and reforming were performed over a biomass-derived char,with toluene as a model compound of tar aromatic substances. And the reaction rules,production distribution and changes of biomass char in process of toluene cracking and reforming were studied. The results indicated that biomass char had a catalytic effect on toluene cracking,and it was approved that microwave heating could favor toluene cracking. By analyzing the results,it was observed that toluene conversion and hydrogen selectivity were directly correlated to bed temperature in cracking reaction.Toluene cracking was optimized at 750℃,and the greatest toluene conversion and hydrogen selectivity were obtained, which were 92. 77% and 91. 94%, respectively. Afterwards, changes in toluene conversion and hydrogen selectivity were insignificant. It was further revealed that the introduction of CO2 could reform toluene into syngas production. At 700℃,the highest conversion rate of 92. 03% was reached at CO2 flow rate of 80 m L / min,accompanied by a maximal syngas yiled rate of 91. 30%. And increasing CO2 flow rate decreased the ratio of H2 to CO dramatically. The lowest ratio of 0. 22 was obtained at CO2 flow rate of 120 m L / mm. The introduction of CO2 also brought about a loss of carbon in biomass char. And carbon loss was maximized to 5. 42% at 700℃. At the same time,the depleted carbon was further converted into additional syngas production,which provided the highest contribution of15. 40% for total syngas production. Finally,it was demonstrated that an excess of CO2 could slow downthe negative effect of carbon deposition on toluene conversion.