Abstract The composite catalysts were prepared from mesoporous alumina as a matrix and Ga-exchanged ZSM-5 as a major catalytic component by the conventional kneading method. The effects of the matrix on the activity and selectivity of aromatics in cracking and dehydrocyclization of n-pentane were investigated. 65-85 wt% of GaZSM-5 was mixed with 0-20 wt% of Al2O3 and 15 wt% of alumina-sol binder. Cracking of n-pentane and successive dehydrocyclization of formed olefins to produce aromatic compounds were performed using a fixed-bed reactor under the conditions, H2 atmosphere and temperature range 450-550 °C. The conversion of n-pentane and the selectivity for aromatics increased with increasing temperature. A catalyst Ga(15)ZSM/10A, where the Ga-exchange ratio was 15%, exhibited the highest conversion among the catalysts with same Ga(15), suggesting that there would be the optimal values of Ga and alumina contents to obtain the high conversion. Further, Ga(15)ZSM/10A exhibited the highest selectivity for aromatics, suggesting that the presence of matrix alumina would appropriately inhibit the cracking to C1 and that the amount of GaZSM-5 would be enough large to increase aromatics to the maximum. Reaction routes and product distributions could be explained by the initial cracking of n-pentane, the small amount of C4 fraction cracking and the successive aromatization through dehydrocyclization of formed olefins.

中文翻译：

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基体对Ga离子交换ZSM-5-氧化铝复合催化剂正戊烷裂解脱氢环化生产芳烃的影响

摘要 以介孔氧化铝为基体，以Ga交换的ZSM-5为主要催化组分，采用常规捏合方法制备了复合催化剂。研究了基体对正戊烷裂解脱氢环化芳烃活性和选择性的影响。65-85重量％的GaZSM-5与0-20重量％的Al 2 O 3 和15重量％的氧化铝-溶胶粘合剂混合。使用固定床反应器在氢气气氛和 450-550 °C 的温度范围内进行正戊烷的裂化和形成的烯烃的连续脱氢环化以生产芳族化合物。正戊烷的转化率和芳烃的选择性随着温度的升高而增加。Ga(15)ZSM/10A 催化剂，其中 Ga 交换率为 15%，在具有相同 Ga(15) 的催化剂中表现出最高的转化率，表明存在 Ga 和氧化铝含量的最佳值以获得高转化率。此外，Ga(15)ZSM/10A 对芳烃表现出最高的选择性，表明基质氧化铝的存在将适当地抑制裂解为 C1，并且 GaZSM-5 的量足够大，可以最大限度地增加芳烃。反应路线和产物分布可以通过正戊烷的初始裂化、少量的 C4 馏分裂化和通过形成的烯烃的脱氢环化连续芳构化来解释。表明基质氧化铝的存在将适当地抑制裂解为 C1，并且 GaZSM-5 的量将足够大以最大程度地增加芳烃。反应路线和产物分布可以通过正戊烷的初始裂解、少量的 C4 馏分裂解和通过形成的烯烃的脱氢环化连续芳构化来解释。表明基质氧化铝的存在将适当地抑制裂解为 C1，并且 GaZSM-5 的量将足够大以最大程度地增加芳烃。反应路线和产物分布可以通过正戊烷的初始裂解、少量的 C4 馏分裂解和通过形成的烯烃的脱氢环化连续芳构化来解释。