摘要
以γ-Al_2O_3为载体,采用等体积浸渍法制备了负载高分散氧化钒催化剂(V_2O_5/γ-Al_2O_3),并通过K,Ca,Mg对V_2O_5/γ-Al_2O_3的表面酸性及钒价态进行调控,研究催化剂表面酸性改性的变化规律及与异丁烷脱氢活性和选择性之间的构效关系。采用XRD、XPS、N_2吸附-脱附、NH_3-TPD和H_2-TPR等方法对催化剂进行表征。实验结果表明,当氧化钒负载量低于7%(w),氧化钒在氧化铝表面处于良好分散状态时,催化剂保持最佳的反应活性和选择性。表征结果显示,碱金属K对V_2O_5/γ-Al_2O_3表面的酸性和V的还原价态具有显著的调节作用,当K添加量(w)为1.5%时,强酸中心几乎被全部抑制,同时保留了适量的弱酸中心,而V的还原价态由2.87+调至3.95+;在1.5%K-V_2O_5/γ-Al_2O_3催化剂上异丁烷脱氢反应340 min后,异丁烷转化率保持在30%以上,异丁烯选择性保持在97%以上。
Highly dispersed V2O5/γ-Al2O3 catalysts for the dehydrogenation of isobutane were prepared through impregnation,and K,Ca and Mg were introduced to modify the surface acidity and vanadium valence of the V2O5/γ-Al2O3 catalysts. The catalysts were characterized by means of XRD,XPS,N2 adsorption and desorption, NH3-TPD,and H2-TPR. It was indicated that, when the vanadium loading was less than 7%（w）,the vanadium oxide dispersed well on theγ-Al2O3 support and the catalysts showed high activity in the dehydrogenation of isobutane to isobutene. The characterization results revealed that the potassium modification had significant adjustment effects on the surface acidity and vanadium valence of the catalysts. The strong acid sites were nearly neutralized when the loading of potassium was 1.5%（w）,while the moderate amount of weak acid sites was kept on the catalyst surface and the vanadium valence was adjusted from 2.87＋to 3.95＋. After the dehydrogenation over the 1.5%（w）K-V2O5/γ-Al2O3 catalyst was conducted for 340 minutes, the conversion of isobutane and the selectivity to isobutene were still kept above 30%and more than 97%,respectively.
出处
《石油化工》
CAS
CSCD
北大核心
2016年第9期1043-1049,共7页
Petrochemical Technology
基金
上海市科学技术委员会资助国际合作项目(14120700700)
重点实验室基金项目(14DZ2273900)
