铋掺杂钒磷氧催化剂选择性氧化碳四烃制顺酐

制备了Bi掺杂的钒磷氧(VPO)催化剂(VPOBi);分别以正丁烷和混合碳四为原料,考察了Bi掺杂量对VPOBi催化剂选择性氧化碳四烃性能的影响。在653K、气态空速2000h~(-1)条件下,正丁烷在Bi掺杂量(摩尔分数)为0.3%的VPOBi催化剂上所得顺酐收率最大(40.4%),混合碳四在Bi掺杂量为0.2%的VPOBi催化剂上所得顺酐收率最大(49.2%)。采用XRD,BET,SEM,H_2-TPR等方法对催化剂进行表征。表征结果表明,Bi的掺杂使VPO催化剂中暴露的(020)晶面显著增多,改变了催化剂的形貌,增大了催化剂的比表面积,提高了催化剂晶格氧的反应性能,使晶格氧能在相对较低的温度下被H_2还原,从而显著改善了VPO催化剂选择性氧化碳四烃制顺酐的性能。

Selective Oxidation of C4 Hydrocarbons to Maleic Anhydride over Bi-Doped VPO Catalysts

The Bi-doped vanadium-phosphorus-oxygen(VPO)catalysts(VPOBi)were prepared. Effects of Bi dopant dosage on activities of the prepared catalysts in selective oxidation of C_4 hydrocarbons to maleic anhydride were investigated with n-butane or mixed C_4 as feedstocks.Under the optimal conditions:reaction temperature 653 K,GHSV 2000h~(-1)and VPOBi as catalyst,yield of maleic anhydride was 40.4% with n-butane as feedstock and 0.3%(mole fraction)Bi as dopant of the catalyst,and its yield reached 49.2% with mixed C4 as feedstock and 0.2% Bi as dopant of the catalyst.The catalysts were characterized by means of XRD,BET,SEM and H_2-TPR.The results showed that introduction of Bi dopant obviously promoted increase of the exposed(020)crystal faces of the catalysts,modified their morphology,and increased their specific surface areas.The activity of lattice oxygen in the catalysts also increased after Bi doping,so that the lattice oxygen could be reduced by H_2 at low temperature.These changes improved the catalyst activity in the selective oxidation of C_4 hydrocarbons to maleic anhydride.