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首页> 外文期刊>Journal of natural gas science and engineering >Sono-dispersion of Cr over nanostructured LaAPSO-34 used in CO2 assisted dehydrogenation of ethane: Effects of Si/Al ratio and La incorporation
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Sono-dispersion of Cr over nanostructured LaAPSO-34 used in CO2 assisted dehydrogenation of ethane: Effects of Si/Al ratio and La incorporation

机译：Cr在纳米结构的LaAPSO-34上的声波分散在二氧化碳辅助的乙烷脱氢中使用：Si / Al比和La掺入的影响

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A series of SAPO-34 supported chromium oxide catalysts varying in the Si content and presence/absence of La3+ ions were prepared by sonochemically impregnation method and tested in the dehydrogenation of ethane with CO2. SAPO-34 supports with Si/Al ratios of 0.1, 0.2, 03 and 0.4 were synthesized via hydrothermal method. The samples were characterized by XRD, BET, FESEM, TEM, ICP, FTIR, EDX and TPD-NH3 techniques. The variation of silicon content indicates that the relative crystallinity, surface area and effective acidity of samples increased with the Si/Al ratio up to 0.2. However, a decreasing trend was observed with further increase of the silicon content. This can be justified by the appearance of irregular particles. It was found that there is the optimum silicon content in the SAPO-34(0.2) support for the best catalytic activity, attributable to higher relative crystallinity, surface area and appropriate surface acidity. The incorporation of La3+ into the SAPO-34(0.2) framework generated in LaAPSO-34 sample was proved by XRD and TEM techniques. The La incorporation not only increases the surface area but also neutralizes mostly strong acid sites, resulted in higher dispersion of Cr species and more effective surface acidity/basicity as evidenced by EDX and TPD-NH3 analysis, respectively. This reflects in higher content of redox Cr species stabilized in comparison with parent SAPO-34(0.2), which alongside homogenous and fine Cr nanoparticles account for the superior catalytic performance and stability of Cr/LaAPSO-34(0.2). It was found that this catalyst effectively dehydrogenated ethane to ethylene in the presence of CO2 at 700 degrees C even after 10 h on-stream operation, giving 42.3% ethylene yield. Following the obtained results, a possible reaction mechanism was also proposed. (C) 2015 Elsevier B.V. All rights reserved.
机译：通过声化学浸渍法制备了一系列硅含量不同，La 3+离子存在/不存在的SAPO-34负载型氧化铬催化剂，并进行了乙烷与CO 2的脱氢反应测试。通过水热法合成了Si / Al比为0.1、0.2、03和0.4的SAPO-34载体。通过XRD，BET，FESEM，TEM，ICP，FTIR，EDX和TPD-NH3技术对样品进行表征。硅含量的变化表明，样品的相对结晶度，表面积和有效酸度随Si / Al比高达0.2的增加而增加。但是，随着硅含量的进一步增加，观察到下降的趋势。这可以通过出现不规则颗粒来证明。发现在SAPO-34（0.2）载体中有最佳的硅含量，具有最佳的催化活性，这归因于较高的相对结晶度，表面积和适当的表面酸度。通过XRD和TEM技术证明了La3 +掺入LaAPSO-34样品中生成的SAPO-34（0.2）框架中。 La的掺入不仅增加了表面积，而且还中和了大部分强酸位，分别导致了Cr种类的分散和更有效的表面酸度/碱度，分别由EDX和TPD-NH3分析证明。这反映出与母体SAPO-34（0.2）相比，稳定的氧化还原Cr物种含量更高，后者与均质和细化的Cr纳米颗粒共同构成了Cr / LaAPSO-34（0.2）的优异催化性能和稳定性。发现即使在运行10小时后，该催化剂在700℃下在CO 2存在下也能有效地将乙烷脱氢成乙烯，得到42.3％的乙烯收率。根据获得的结果，还提出了可能的反应机理。 （C）2015 Elsevier B.V.保留所有权利。

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