分级孔HZSM-5催化烘焙预处理杨木快速热解制取芳烃

The catalytic fast pyrolysis of torrefied poplar wood to aromatic compounds over hierarchical HZSM-5

采用NaOH溶液对HZSM-5进行处理,通过XRD,BET,NH3-TPD方法对改性前后的HZSM-5进行表征。在管式炉中对杨木进行烘焙预处理,利用改性前后的HZSM-5在催化剂评价装置中进行烘焙预处理杨木的催化热解实验,探究杨木烘焙预处理温度和HZSM-5碱处理浓度对芳烃产物的影响。研究结果表明,碱处理后的HZSM-5形成了含有微-介孔的分级孔道结构,酸分布有所变化;随着NaOH浓度的增加,生物油中多环芳烃的含量逐渐降低,单环芳烃的含量呈现先增加后降低的趋势,在0.3-HZSM-5催化下达到最高产率58.12%;随着烘焙温度的升高,生物油中单环芳烃的含量先增加后降低,含氧化合物的含量先减小后增加,260℃烘焙预处理杨木催化热解效果最佳,芳烃化合物总收率达到82.01%,其中单环芳烃选择性达到70.87%。

HZSM-5 zeolite was modified by NaOH with varying concentrations.The raw and modified HZSM-5 zeolites were characterized by XRD,BET,and NH3-TPD.Poplar wood(PW),pretreated by torrefaction at different temperatures,was catalytically pyrolyzed using a catalyst evaluation device with raw and modified HZSM-5 as catalysts.The effects of torrefaction temperature and alkali concentration on aromatics were investigated.The results showed that the modified HZSM-5 zeolites formed micro-mesopores structure while the acid distributions were changed after alkali treatment.The content of polycyclic aromatic hydrocarbons in bio-oil was gradually decreased with the increase of NaOH concentration.On the other hand,the content of monocyclic aromatic hydrocarbons was increased first and then decreased with increasing NaOH concentrations.The highest yield of monocyclic aromatic hydrocarbons(58.12%)was obtained in the presence of 0.3-HZSM-5.As the torrefaction temperature increased,the content of monocyclic aromatic hydrocarbons increased first and then decreased,whereas the content of oxygenated compounds exhibited a different trend with monocyclic aromatic hydrocarbons.The total yield of aromatic compounds reached up to 82.01%and the selectivity of monocyclic aromatic hydrocarbons was 70.87%when the torrefaction temperature was 260℃.