MoO_3催化剂上苯酚加氢脱氧制取芳烃研究

HYDRODEOXYGENATION OF PHENOL TO AROMATIC HYDROCARBONS OVER MoO_3 CATALYST

以(NH_4)_6Mo_7O_(24)·4H_2O为前驱体通过简单的焙烧方法制备非负载型MoO_3催化剂,通过低温N_2吸附、X射线衍射(XRD)、X射线光电子能谱(XPS)和H_2程序升温还原(H_2-TPR)技术对催化剂特性进行表征,以苯酚为模型化合物进行加氢脱氧实验制备以苯为主要产物的芳烃化学品。重点考察反应温度、反应时间、反应气组成等参数对苯酚转化率、目标产物苯选择性的影响,并就氧化钼催化加氢脱氧反应机制及催化剂的可重复使用性能进行讨论与考察。实验结果表明,在340℃、0.5 MPa H_2与3.0 MPa N_2混合气氛的优化工况下,苯酚的转化率达到98.1%,产物苯选择性达到99.5%。MoO_3催化材料中的氧缺陷位是催化苯酚分子中C_(AR)—OH键直接氢解生成芳烃苯的主要活性位。此外,MoO_3重复使用3次后催化活性仍无明显下降,表明该催化剂的加氢脱氧催化活性具有良好的稳定性。

MoO3 catalyst was prepared by calcination using(NH4)6 Mo7 O24·4 H2 O as precursor and was characterized by XRD,XPS,H2-TPR and low temperature N2 adsorption.Aim to produce arene,hydrodeoxygenation(HDO)was carried out using phenol as model compound.The focus was the effects of reaction temperature,reaction time and reaction gas conposition on the phenol conversion rate and selectivity of target product.The catalytic mechanism of phenol HDO over MoO3 and the recyclability of catalyst were also discussed.The results showed that MoO3 can effectively convert phenol to benzene with 98.1%and 99.5%selectivity of benzene under optimal conditions(340℃,pH2=0.5 MPa,pN2=3 MPa).And the oxygen deficiency of MoO3 was deemed to be the active center in the hydrodeoxygenation of phenol,which accounts for the hydrolysis of CAR——OH to benzene.In addition,MoO3 exhibited excellent recyclability.The catalytic activity remains at the same high level when the catalyst was repeatedly used for three times in the HDO of phenol,suggesting an excellent stability.