摘要
This paper describes the effect of the prepara- tion method of binary oxide supports （TiO2-Al2O3） on catalytic performance of V2O5/TiO2-Al2O3 catalysts for methanol selective oxidation to dimethoxymethane （DMM）. The TiO2-A1203 supports are synthesized by a number of methods including mechanical mixing, ball milling, precipitation, co-precipitation, and sol-gel method, which is followed by incipient wetness impregnation to produce V2O5/TiO2-Al2O3 catalysts. Among these samples, the V2O5/TiO2-Al2O3 catalyst prepared by the sol-gel method has the best catalytic performance with a maximum methanol conversion of 48.9 % and a high DMM selectivity of 89.9 % at 393 K, showing superior performance than V2O5/TiO2 and V2O5/Al2O3. The excellent catalytic performance of V2O5/TiO2-Al2O3 is attributed to the effective interaction between the active component and the mixed support. Such interaction changes the chemical states of supported active V components, produces an increased amount of V^4＋ species, and facilitates the electron transfer between support and active component. Additionally, the incorporation of titanium cation into the alumina structure could also help produce an appropriate amount of acidic sites, which increases the DMM selectivity. The coordinated environment of the dispersed vanadia on TiO2-Al2O3 mixed support improves the catalytic efficiency on methanol oxidation to DMM.
介绍了甲醇选择性氧化制备二甲氧基甲烷(DMM)过程中,二元Ti O2-Al2O3氧化物载体的制备方法对V2O5/Ti O2-Al2O3催化剂性能的影响.考察的制备方法包括机械混合、球磨、沉淀、共同沉淀、溶胶凝胶法,随后通过等体积浸渍制备出V2O5/Ti O2-Al2O3催化剂.其中,溶胶凝胶法制得的V2O5/Ti O2-Al2O3催化剂具有最高的催化活性,在393 K下表现出48.9%的转化率和89%的DMM选择性,优于V2O5/Ti O2,V2O5/Al2O3催化剂.V2O5/Ti O2-Al2O3优良的性能是由于催化活性组分与混合型载体之间有效的相互作用.这种相互作用改变了活性V组分的化学态,生成了更多的V4+物种,促进了载体与活性组分之间的电子转移.此外,Ti离子可通过嵌入Al2O3晶体来生成含量适宜的酸性位,进而提高DMM的选择性.
基金
supported by the National Natural Science Foundation of China(21006068,21222604)
the Program for New Century Excellent Talents in University(NCET-10-0611)
Specialized Research Fund for the Doctoral Program of Higher Education(20120032110024)
the Scientific Research Foundation for the Returned Overseas Chinese Scholars(MOE)
the Program of Introducing Talents of Discipline to Universities(B06006)
