摘要
在气相氧浓度10%条件下,研究了催化剂中各组元含量及助剂K、P、Nb对催化活性的影响。结果表明,在一定浸涂量下,V含量有一最佳值(4.38%<mol>),K含量达0.3%(mol)时,催化剂活性处于最佳值。XRD分析表明:由于助剂的存在,催化剂结构中V_2O_(4.33)的晶胞尺寸发生了畸变。经计算,沿001面,V_2O_(4.33)的C轴缩短了0.018nm。IR测试表明,由于助剂的作用使V=O键振动频率发生改变,说明助剂对V=O键有诱导作用。在空速3.000h^(-1),氧浓度10%,邻二甲苯60g/m^3,床层最高温度450℃条件下,苯酐重量收率可达117.4%。
The gas phase oxidation of o-xylene to phthalic anhydride at low oxygen concentration was studied. At the given conditions: space velocity 3000h^(-1), feed gas oxygen concentration 10%, o-xylene in raw material gas 60 g/m^3, and reaction temperaturc at heat point 450℃, the yield of phthalic anhydride was 117.4% by weight. The results showed: the interaction of V-Ti influenced the catalytic activity greatly. With the given immersing amount. the V amount has a saturation value 4.38% (mol). Promoter K, P, Nb amount has important effect on catalytic activity. The activity has the best value when the potassium amount is 0.3% (mol). The XRD analysis also confirmed that the crystal calculation result showed, the C axis in the V_2O_(4.33)crystal shortened by 0.018 nm along the (001) face, and preferred orientation of the (001) face increase with the potassium amount. The IR results also confirmed that the vibration frequency of the V—O bond shifted from 1025 cm^(-1) to 1095 cm^(-1).
关键词
催化剂
二甲苯
苯酐
xylene
phthalic anhydride
catalyst
oxidation
vanadium oxide
