P改性NiW/γ-Al2O3的低温焦油芳烃组分加氢性能研究
Effect of phosphorus modification on the catalytic properties of NiW/γ-Al2O3 in the hydrogenation of aromatics from coal tar
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摘要: 以γ-Al2O3为载体,采用浸渍法制备了不同P添加量的负载型NiW加氢催化剂,采用固定床加氢装置,对模型化合物萘和低温焦油富集的芳烃组分进行了催化加氢。催化剂采用N2吸附、XRD、H2-TPR、XPS以及NH3-TPD的方法进行表征,加氢产物采用GC-MS和GC×GC-TOFMS进行分析。结果表明,P助剂能够扩大催化剂的孔径并促进活性金属组分在载体表面的分散;当P含量为1.0%~1.5%时,能够促进Ni-W-O混合相生成,并提高催化剂表面弱酸的含量;萘加氢反应的转化率和十氢萘的选择性也在添加1.0%的P时达到最高,分别为80%和50%左右;低温焦油芳烃组分的催化加氢结果显示,芳烃饱和加氢反应占优,绝大部分芳烃转化为环烷烃,且催化剂具有显著的脱除杂原子效果。Abstract: Modified with different contents of phosphorus, the NiW/γ-Al2O3 catalysts prepared using the impregnation method were used to catalyze the hydrogenation reaction of naphthalene and the aromatics compounds separated from low temperature coal tar in a fixed-bed reactor. The properties of the catalysts were characterized by N2 adsorption, XRD, H2-TPR, XPS and NH3-TPD. The products were analyzed by GC-MS and GC×GC-TOFMS. Results showed that the addition of P can enhance the distribution of Ni and W compounds on the surface of supports and expand the pore diameter. Adding 1%~1.5%P could generate more Ni-W-O phase and increase the proportion of the weak acid. The results of naphthalene hydrogenation indicated that the highest conversion rate of nearly 80% and the decalin yield of over 50% were achieved when using the NiW+1%P catalyst. For the tests using the catalyst with 1.0%P to catalyze the hydrogenation of enriched aromatics compounds from coal tar, the results indicated that the effect of transforming aromatics into cycloalkanes and the removal of heteroatoms were remarkable in the presence of the catalyst.