La改性多级孔HZSM-5在线催化提质生物油

采用Na₂CO₃溶液对HZSM-5分子筛进行预处理,然后采用浸渍法对预处理后的HZSM-5进行不同负载量的La改性,通过XRD、BET、SEM-EDS和Py-IR等方法对改性前后的HZSM-5进行表征。利用改性前后的HZSM-5在两段式固定床反应器上进行生物质热解产物在线催化实验,对得到的生物油有机相进行理化特性和组成成分分析。结果表明,经过Na₂CO₃溶液处理后,使HZSM-5分子筛形成了含有微-介孔的多级孔孔道结构,La的改性未改变HZSM-5的MFI结构,但改变了分子筛的酸分布。随着La负载量的增加,生物油有机相产率、密度、运动黏度及氧含量先减小后增加,含氧化合物和羰基类化合物含量同样呈现先减小后增加的变化趋势。经过最佳质量分数为5%的La负载后的多级孔HZSM-5分子筛制得的生物油中,有机相高位热值高达37.7 MJ/kg,烃类物质含量达到了49.86%,含氧化合物和羰基类化合物含量分别减少了32.43%和57.03%。

La modified hierarchical porous HZSM-5 catalysts for online upgrading of the pyrolysis vapors from rape straw

To improve the characteristics of the bio-oil, La modified HZSM-5 with hierarchical structure was applied in the catalytic pyrolysis of biomass. First, the HZSM-5 zeolite was pretreated with Na₂CO₃ solution, and then the pretreated HZSM-5 was modified with different loadings of La by impregnation. The modified HZSM-5 were characterized by XRD, BET, SEM-EDS and Py-IR, respectively. The catalysts were used in the process of preparing bio-oil and the bio-oil organic phases were studied from the aspects of composition and physical properties. The results showed that the modified HZSM-5 catalysts formed micro/meso-porous pore structure and retained typical MFI topology structure. But the modification of La changed the acid distribution of the zeolite. With the increase of loadings of La, the yield, density, kinematic viscosity and oxygen content of bio-oil organic phase decreased first and then increased, while the content of oxygenated compounds and carbonyl compounds showed the same tendency as well. The hierarchical porous HZSM-5(La loading were 5%) catalyst had a better effect on the removal of aldehyde and ketone contained in the bio-oil organic phase which improved the stability of the bio-oil, the oxygenated compounds and the carbonyl compounds decreased by 32.43% and 57.03%, respectively. Meanwhile, the hydrocarbon content and the higher heating value of the bio-oil organic phase reached 49.86% and 37.7MJ/Kg, respectively.