Mechanism of n-butane skeletal isomerization on H-mordenite and Pt/H-mordenite
Mechanism of n-butane skeletal isomerization on H-mordenite and Pt/H-mordenite
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DOI：
10.1016/j.jcat.2014.12.035
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发表时间：
2015-10
影响因子：
7.3
通讯作者：
Matthew J. Wulfers;F. Jentoft
中科院分区：
文献类型：
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作者：
Matthew J. Wulfers;F. Jentoft
用动力学和同位素标记实验研究了常压和543-583kK温度下正丁烷在氢丝光沸石和铂/氢丝光沸石上的反应途径。丁烯在催化剂上形成或存在于进料中，控制了单分子和双分子反应途径的相对速度。异丁烷生成的真实活化能为120-134kJ/mol。异丁烷与异丁烯在铂/氢丝光沸石上的反应级数为1.0-1.2，符合以单分子为主的生成途径。歧化产物的级数接近2表明了双分子的形成途径。从1，4-13C2-正丁烷的转化率来看，丁烯浓度从不到20ppm增加到约120ppm，大大提高了双分子骨架异构化的速度。这些发现解释了反应条件如何影响产物选择性，并澄清了关于丁烷在固体酸上异构化的争议。
Kinetics and isotope labeling experiments were used to investigate the reaction pathways ofn-butane on H-mordenite and Pt/H-mordenite at atmospheric pressure and temperatures of 543–583 K. Butenes, either formed on the catalyst or present in the feed, controlled the relative rates of mono- and bimolecular reaction pathways. The true activation energy for isobutane formation was found to be 120–134 kJ/mol. The reaction order for isobutane formation with respect ton-butene on Pt/H-mordenite was 1.0–1.2, consistent with a predominately monomolecular route of formation. An order close to 2 for disproportionation products indicated a bimolecular route of formation. An increase of the butene concentration from less than 20 ppm to about 120 ppm greatly increased the rate of bimolecular skeletal isomerization, as determined from conversion of 1,4-13C2-n-butane. The findings explain how reaction conditions affect product selectivity and clarify the controversy around butane isomerization on solid acids.