摘要
分别用超临界流体干燥方法和传统方法制备了用于丁烷选择性氧化制顺酐的VPO催化剂 .用超临界流体干燥方法制备的催化剂VPOⅡ的比表面积高达 38 8m2 /g ,而用传统方法制备的催化剂VPOⅠ的比表面积只有10 7m2 / g .XRD分析表明 ,除催化剂VPOⅡ中的VOPO4 相含量比催化剂VPOⅠ稍多外 ,这两种催化剂的主要结构均为 (VO) 2 P2 O7相 .在有氧和无氧条件下进行的丁烷氧化制顺酐的催化反应结果表明 ,用超临界流体干燥方法制备的催化剂不仅具有较高的顺酐收率 ,而且含有更多的可在无氧条件下参与选择性氧化反应的晶格氧 (催化剂VPOⅡ的可利用选择性晶格氧量比催化剂VPOⅠ增加了 1 5倍 ) .用超临界流体干燥方法可以改善催化剂性能的原因可能与催化剂具有较大的比表面积和较多的V5+
The vanadyl pyrophosphate (VPO) catalysts for the n butane selective oxidation to maleic anhydride were prepared by means of supercritical fluid desiccation (VPOⅡ) and conventional (VPOⅠ) methods, respectively. The BET surface area of the VPOⅡ catalyst (38 8 m 2/g) is remarkably higher than that of the VPOⅠ catalyst (10 7 m 2/g). XRD patterns show that both the catalysts have almost the same main phase of (VO) 2P 2O 7, except that the content of the VOPO 4 phase in VPOⅡ is slightly higher than that in VPOⅠ. The performance of the VPOⅡ catalyst for the n butane selective oxidation to maleic anhydride in the absence of oxygen or in the butane/air co feed is better than that of the VPOⅠ catalyst. The pulse reaction results indicate that the amount of selective lattice oxygen in VPOⅡ increases by 150% compared with VPOⅠ. The co feed evaluations of 1 5% butane in air over the VPOⅡ and VPOⅠ catalysts give 51 8% and 41 9% of maleic anhydride yields under the reaction conditions of 420 ℃, atmospheric pressure and GHSV= 1?000 h -1 , respectively. The promotional effect of the supercritical fluid desiccation method on the catalytic performance may be attributed to the significant increase in the surface area and V 5+ ions in the VPO catalyst.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2001年第5期427-431,共5页
基金
国家重大自然科学基金资助项目 ( 2 9792 0 73 2 )
