摘要
以γ-Al2O3为载体,采用共浸渍和程序升温H2还原的方法,制备了一系列钒掺杂的磷化钨催化剂,对催化剂进行了XRD,BET,TG和XPS表征。通过高压微反装置,在3MPa,360℃和空速为4h-1的条件下,考察了催化剂咔唑HDN活性。结果表明,掺杂钒在一定程度上影响了活性组分WP在载体表面的分散,当钒掺杂量达到5%时,钒与载体和活性组分间产生明显的协同效应使其结构发生细微变化。掺杂钒使催化剂前体表面的W物种起始磷化还原温度提高而磷化还原程度降低,而载体表面高价态W6+数量提高。钒掺杂量为1%的催化剂能明显增加咔唑HDN反应活性,其咔唑HDN转化率比不加钒的催化剂提高12.7%。磷化钨催化剂咔唑HDN反应有3条路径,其中直接氢解脱氮反应(路径1)选择性只有3.2%,而先加氢使两个苯环都饱和然后脱氮的反应路径(路径3)占绝对优势,其选择性为91.0%。与未掺杂钒的磷化钨催化剂相比,掺杂1%钒的催化剂的咔唑HDN反应直接氢解脱氮选择性有所降低,通过路径3的反应选择性降低6.7%,而先加氢使一个苯环饱和然后脱氮(路径2)的选择性提高7.3%。
γ-Al2 O3 as a support, a series of tungsten phosphide catalysts containing vanadium were prepared by the method of co--impregnation and temperature programmed reduction （TPR） in H2. The catalysts were characterized by XRD, BET, TG, XPS. Carbazole hydrodenitrogenation（HDN） activities of catalysts were tested by a high pressure micro--reactor in condition of 3 MPa, 360 ℃ and a space velocity of 4 h^-1. The result show that dispersity of active species WP on the support surface is affected by adding some content of vanadium into tungsten phosphide catalyst. The cooperative effect is greatly between vanadium and support and active species with vanadium content of 5 %, which resulting in a Very smaller changing in XRD pattern. Adding some content of vanadium during the preparation of catalyst produced the original phosphiding-- reduction temperature of W species on the support surface for catalysts precursor increasing and phosphiding--reduction extent decreasing, while the amount of high valence of W^6＋ on the surface of catalysts are improved. Catalyst with vanadium content of 1 % is favor to earbazloe HDN reaction, which gaving 12.7 % higher carbazole HDN conversion than that without vanadium. It is also observed that carbazole HDN reaction showed three paths： a very low direct denitrogenation selectivity（only 3.2%, the first path way ） and a high hydrodenitrogenation selectivity （hydrogenation to saturating one benzene rings followed by denitrogenation, the second path way, and hydrogenation to saturating two benzene rings followed by denitrogenation, the third path way）. The third path way is a primary rout and the HDN selectivity reached 91.0%. Compared to the tungsten phosphide catalyst without vanadium, carbazole HDN selectivity of catalyst with 1% content of vanadium showed a slightly decreased by the first path and gave a 6.7 % lower by the third path, 7.3 % higher by the second path.
出处
《石油化工高等学校学报》
CAS
2009年第3期24-27,32,共5页
Journal of Petrochemical Universities
基金
国家重点基础研究发展规划项目(No.G2000048003)
北京市自然科学基金项目(2052009)
北京市属高校人才强教深化计划资助项目(PHR200907129)
关键词
钒
咔唑
磷化钨
加氢脱氮
选择性
Vanadium
Carbazole
Tungsten phosphide
Hydrodenitrogenation
Selectivity
