共查询到16条相似文献,搜索用时 187 毫秒
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酸处理的铌酸催化合成乙基叔丁基醚 总被引:3,自引:0,他引:3
用XRD、BET和TG/DTG等考察了水洗铌酸、硝酸处理的铌酸和经硝酸和磷酸处理后的铌酸结构特征和表面酸性。试验研究了用(硝酸+磷酸)处理的铌酸对制备乙基叔丁基醚(ETBE)催化反应活性的影响,对合成ETBE的醚化反应条件进行了考察。试验结果表明,经硝酸和磷酸处理后的铌酸具有较好的催化合成ETBE的醚化反应性能和稳定性。适宜醚化反应条件为反应温度130℃、乙醇与叔丁醇摩尔比2.0、反应时间3.0h和催化剂用量为原料质量的9.10%。 相似文献
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研究了铌酸催化剂上甲苯硝化反应的区域选择性。结果表明,当反应温度为40℃,反应时间为60 min时,以CCl4为溶剂,以质量分数为95%的硝酸为硝化剂,在醋酐存在条件下,经300℃焙烧3 h后的铌酸催化剂,对甲苯硝化表现出了强的区域选择性;催化剂用量为0.8 g,甲苯硝化产物邻对位摩尔比达1.20,较硝硫混酸的1.67显著降低,产物得率达99.7%。且该催化剂循环使用5次,催化活性变化很小。制备了4种改性铌酸催化剂,结果分析表明,改性铌酸催化剂对甲苯硝化均表现出了比铌酸催化剂强的区域选择性,分别以硫酸铈改性的固体铌酸、硫酸铈和磷酸改性的铌酸、硝酸改性的铌酸、硝酸和磷酸改性的铌酸为催化剂,甲苯硝化产物的邻对位摩尔比可分别达1.15,1.11,1.09,1.04。 相似文献
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M. Balaraju 《Fuel Processing Technology》2010,91(2):249-253
Acetylation of glycerol to yield mono, di and triacetin (acetylated glycerol) was carried over niobic acid supported tungstophosphoric acid (TPA) catalysts. The catalysts with varying TPA content were prepared and characterized by different techniques. The characterization results reveal the presence of well-dispersed Keggin ion on support. The results suggest that the glycerol conversion and selectivities depend on the acidity of the catalysts, which in turn is related to the content of TPA on niobic acid. The change in conversion and selectivities during the acetylation also is attributed to the reaction time, catalyst concentration and glycerol to acetic acid molar ratio. 相似文献
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Taka -aki Hanaoka Kazuhiko Takeuchi Takehiko Matsuzaki Yoshihiro Sugi 《Catalysis Letters》1990,5(1):13-16
Solvolysis and isomerization of phenyloxirane were studied with niobic acid (Nb2O5.xH2O) as catalyst. In aqueous solution, niobic acid showed much higher hydrolysis performances in activity and selectivity than other solid acid catalysts. Selectivity of alcoholysis with methanol was much higher than that with other alcohols because of simultaneous isomerization and dehydration of alcohol. 相似文献
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将铌酸用于催化合成乙酸苯乙酯 ,在醇酸摩尔比 1∶5 ,回流反应 2h ,催化剂用量 (以 1mol醇计 )为 5g的条件下 ,酯收率可达 84 .3%以上。催化剂不经处理 ,可多次循环使用 ,不污染环境 ,相对于一些其他催化剂 ,具有明显的优点。 相似文献