Abstract:

The effects of calcination temperature on the structure, phase, reduction properties and catalytic behavior of olivine in toluene cracking were investigated by BET analysis, XRD, H₂-TPR and TEM.It was found that the crystal form and catalytic activity of olivine were markedly influenced by calcination temperature. The main phases of olivine calcined at a lower temperature were Mg₂SiO₄ and Fe₂O₃. Increasing the calcination temperature to over 1100℃, Fe₂O₃ phase disappeared gradually and (Fe, Mg)SiO₃ phase was formed, causing a significant decrease in the number of active sites.The perfect catalytic activity was related to higher free iron oxide contents which can be realized by appropriate thermal treatment.In the experiment, the olivine calcined at 900℃ showed the best catalytic activity and high resistance to carbon deposition.

Key words:

焙烧温度, 橄榄石, 催化裂解, 甲苯

摘要：

以橄榄石为催化剂，通过N2物理吸附、XRD、H₂-TPR和TEM等手段研究了焙烧温度对催化剂的结构、物相、还原性能以及甲苯裂解反应活性的影响。结果表明，焙烧温度对催化剂结构和活性影响显著，低温焙烧时主要存在Mg₂SiO₄和Fe₂O₃的晶相衍射峰，随着焙烧温度的升高，Fe₂O₃的晶相衍射峰逐渐消失，随之出现了非常明显的 (Fe, Mg)SiO₃的衍射峰。选择适中的焙烧温度可以增加表面上可还原Fe₂O₃的量，从而拥有较高的甲苯裂解活性位。在实验考察范围内，900℃焙烧的橄榄石表现了最高的甲苯裂解活性。TG结果表明，该温度焙烧的橄榄石具有较好的抗积炭性能。

关键词:

焙烧温度, 橄榄石, 催化裂解, 甲苯