乙烷在煤焦及石英砂床层上的裂解实验

Cracking of Ethane in Coal Char Bed and Quartz Sand Bed

采用小型石英管固定床反应装置,在850～1000℃下,对空床、煤焦及石英砂床层上的乙烷裂解进行了研究,并采用扫描电子显微镜和 BET 法对反应前后的煤焦进行表征。实验结果表明,乙烷裂解产物包括氖气、甲烷、乙烯和积碳;反应温度越高,裂解越完全,生成的氢气越多;850～1000℃时,反应达到稳态后乙烷在空床、煤焦和石英砂床层上裂解的转化率及产物收率接近,乙烷转化率在95%以上,说明反应温度高于850℃时,乙烷无需催化剂和反应表面即能接近完全裂解。乙烷在新鲜煤焦床层上的裂解更为彻底,但随反应的进行,沉积的积碳使煤焦逐渐失去催化活性,乙烷裂解时更易生成甲烷和乙烯。

For the sake of studying co-conversion of coal and oil refinery off-gas for syngas production, ethane as one of the major components of oil refinery off-gas was cracked in a fixed bed reactor with coal char and quartz sand separately in temperatures range of 850 - 1 000 ℃. The products of ethane cracking are hydrogen, methane, ethylene and carbon. The higher the reaction temperature is, the more completely ethane cracks and the produced more hydrogen is. In the temperatures range of 850 - 1 000℃, after the reaction attains steady state, no matter the cracking is in quartz sand bed, coal char bed and even in empty reactor, conversions of ethane is above 95% and yields to products are similar. The facts indicates that ethane can completely decompose through thermal cracking without catalyst and reactive surface at temperatures higher than 850 ℃. Fresh coal char has a significant catalytic effect on complete cracking of ethane. Methane and ethylene yields increase with reaction time due to deactivation of the coal char caused by carbon deposition on its surface.