SBA-15负载钒氧化物催化剂上甲烷选择氧化反应

对SBA-15负载的钒、钼、钨氧化物催化的甲烷选择氧化反应性能进行了比较,发现VO_x/SBA-15催化剂优于MoOx/SBA-15和WOx/SBA-15催化剂.针对钒氧化物催化剂,考察了不同钒源、不同载体以及少量P元素的添加对催化性能的影响,结果表明以SBA-15为载体的催化剂的性能好于MCM-41和Cab-O-Sil为载体的催化剂;与V₂O₅,VO(C₂O₄)相比,NH₄VO₃是制备性能良好的VO_x/SBA-15的钒源;在VO_x/SBA-15中,添加少量P元素后,HCHO的选择性有一定程度的提高.XRD,N₂物理吸附、UN-Raman和H₂-TPR表征结果表明,负载量低于3 wt%时,钒组分可能主要以高分散的单核的VO_x物种存在,我们推测该物种对甲烷选择氧化制甲醛起关键作用.

SBA-15 Supported Vanadium Oxide Catalyst for Selective Oxidation of Methane

The VO x/SBA-15 has been found to be a better catalyst for the selective oxidation of methane to formaldehyde than SBA-15-supported Mo and W oxides. The influences of catalyst support and vanadium source on catalytic performances have been studied. The results show that SBA-15 is a better support than MCM-41 and Cab-O-Sil, and the catalyst with NH 4VO 3 as the precursor exhibits higher performances. The addition of phosphorus has been found to enhance slightly the selectivity to HCHO. Characterizations by XRD, N 2 physical adsorption, Raman spectroscopy and H 2-TPR suggest that the supported VO x species with loading amounts lower than 3 wt% be highly dispersed (probably as monomer) and contribute to the selective oxidation of methane to formaldehyde.