Zn-P复合改性HZSM-5在线催化热解获取生物油的研究

Study on preparation of refined oil by upgrading of pyrolytic vapors using Zn-P / HZSM-5 zeolite

为进一步提高精制生物油的制取效率和燃料品质,采用Zn和P对HZSM-5分子筛进行复合改性,使用XRD、SEM EDS、ICP-AES、BET等方法表征改性HZSM-5分子筛,考察了Zn、P改性对精制生物油理化特性和液相产物的化学组成以及对HZSM-5抗结焦性能的影响。结果表明,Zn、P在HZSM-5表面负载均匀,Zn、P改性未影响HZSM-5的晶体骨架结构,改性HZSM-5的比表面积随着Zn负载量的上升而减少;Zn负载量为3%时,催化热解得到的精制生物油含氧量为10.67%,热值为36.76 MJ/kg,p H值为5.85,精制生物油品质得到显著提升;液相产物中酸类、醛类和酮类等不期望物质相对含量显著下降,芳香族化合物相对含量显著增加,芳香族化合物相对含量为91.93%,其中,芳香烃为74.63%;HZSM-5因负载P使得其相对结焦量明显降低,显著增强了HZSM-5的稳定性;Zn改性促进了氢原子转移和碳正离子的形成,有利于提高HZSM-5分子筛的芳构化性能。

Zn and P were selected to modified HZSM-5 molecular sieve for further improving the production and fuel quality of refined bio-oil. Analysis methods including XRD, SEM EDS, ICP-AES and BET were applied to characterize the modified HZSM-5 molecular sieves. The influence of physical and chemical properties of refined oil and chemical composition of aqueous phase and the anti-coking ability of modified HZSM-5 with the loading of Zn and P were studied. The results showed that the framework of modified HZSM-5 molecular sieves was not influenced by the modification of Zn and P, which were distributed on the surface of HZSM-5 uniformly. The BET of modified HZSM-5 were declined when Zn loading mass was increased. The physical and chemical properties of refined bio-oil when Zn loading mass was 3% were as follows:oxygen content was 10 . 67%, high calorific value was 36. 76 MJ/kg, pH value was 5. 85. Meanwhile, the relative contents of acids, alcohol and ether, aldehyde and ketone in aqueous phase were dropped significantly. Aromatic compounds and aromatic hydrocarbon were increased significantly with the ralative contents were 91. 93% and 74. 63% respectively. The anti-coking ability of modified HZSM-5 was enhanced with the P loading, which enhanced the stability of HZSM-5. Zn loading promoted the formation of carbenium ion and hydrogen transfer, which improved HZSM-5 molecular sieve aromatization performance.