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首页> 外文期刊>ACS catalysis >Oxidative Dehydrogenation of Ethane with CO2 over Flame-Made Ga-Loaded TiO2
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Oxidative Dehydrogenation of Ethane with CO2 over Flame-Made Ga-Loaded TiO2

机译：火焰Ga负载TiO2上的CO2氧化乙烷脱氢。

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摘要

The influence of the Ga content (0-17 wt %) on the structural properties and the catalytic behavior of flame-synthesized TiO2-supported gallium oxide in the oxidative dehydrogenation of ethane (ODHE) has been investigated in a continuous tubular microreactor using CO, as a mild oxidant. The gallium oxide-titania powders consisted of nonporous spherical particles of about 10 nm average diameter, as indicated by HRTEM and X-ray line broadening, and had a specific surface area of about 120 m(2)/g. XRD showed no reflections corresponding to Ga2O3 in the as-prepared samples, indicating high dispersion of the Ga constituent. At higher Ga loading (>14 wt %) stronger acidic sites became prominent, as indicated by NH3-TPD and DRIFTS. The ethene yield increased with Ga loading up to about 10 wt %. The molar CO2/C2H6 ratio in the feed, reaction temperature, and space velocity were decisive parameters for achieving maximum ethene yield. The ethene yield achieved was 22% using a CO2/C2H6 ratio of 2.5, 700 degrees C, and a space velocity of 6000 L/((kg of cat.) h), corresponding to 57% ethane conversion at 38% selectivity to ethene. After reaction (1 h on stream) all catalysts showed significant coking and a loss of surface area depending on the Ga content. Catalysts with higher Ga content were more resistant toward sintering but showed more severe coking due to the presence of stronger acidic sites. Raman spectroscopy revealed that all spent catalysts were covered with both D- and G-type carbon. Both carbon deposition and reduction of catalyst surface area led to a significant decrease in activity with time on stream, while the selectivity to ethene increased up to above 70%. The catalysts could efficiently be regenerated by exposing them for 10 min to air at a reaction temperature of 700 degrees C, providing a base for the development of a dynamic process consisting of alternative ODHE/regeneration cycles.
机译：在采用CO的连续管式微反应器中，研究了Ga含量（0-17 wt％）对火焰合成的TiO2负载的氧化镓在乙烷（ODHE）氧化脱氢中的结构性能和催化性能的影响，作为温和的氧化剂。氧化镓-二氧化钛粉末由平均直径约10 nm的无孔球形颗粒组成（如HRTEM和X射线线展宽所示），比表面积约为120 m（2）/ g。 X射线衍射表明在制备的样品中没有对应于Ga 2 O 3的反射，表明Ga成分的高度分散。如NH3-TPD和DRIFTS所示，在较高的Ga含量（> 14 wt％）下，更强的酸性位变得明显。乙烯的收率随着Ga含量增加到约10 wt％而增加。进料中的CO2 / C2H6摩尔比，反应温度和空速是获得最大乙烯收率的决定性参数。使用2.5 / 700的CO2 / C2H6比率和6000 L /（（kg kg.h）h的空速）所获得的乙烯收率为22％，相当于在38％的乙烯选择性下乙烷转化率为57％ 。反应后（运行1小时），所有催化剂均显示出明显的焦化和表面积损失，具体取决于Ga含量。 Ga含量较高的催化剂对烧结的耐受性更高，但由于存在较强的酸性位，因此显示出更严重的焦化。拉曼光谱表明，所有用过的催化剂都被D型和G型碳覆盖。碳沉积和催化剂表面积的减少均导致活性随生产时间的显着降低，而对乙烯的选择性增加至高达70％以上。通过将催化剂在700摄氏度的反应温度下暴露于空气中10分钟，可以有效地使其再生，从而为开发由交替ODHE /再生循环组成的动态过程提供了基础。

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