This study focuses on the modification of ZSM-5 in order to enhance the catalytic cracking of refinery naphtha to produce light olefins. ZSM-5 was metal modified using different loadings (0.5–5 wt%) of Fe and Cr via the impregnation method. The metal modified ZSM-5 samples are compared and the effect of metal loading on the physicochemical properties and catalytic performance is investigated. Fe and Cr modification had an effect on both the physicochemical properties of the catalysts as well as catalytic activity and selectivity. Metal loading caused a decrease in the specific surface area which decreased further with increased metal loading. Fe had a greater effect on the total acidity in particular strong acid sites when compared to Cr. The optimum Fe loading was established which promoted selectivity to olefins, in particular propylene. Fe also had a dominant effect on the P/E ratio of which a remarkable ratio of five was achieved as well as enhanced the stability of the catalyst. Cr was found to be a good promoter for selectivity to BTX products with a two-fold increase observed when compared to Fe-modified catalysts.

中文翻译：

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石脑油的催化裂化：铁和铬浸渍的ZSM-5对烯烃选择性的影响

这项研究集中于ZSM-5的改性，以增强炼油厂石脑油的催化裂化以生产轻质烯烃。通过浸渍方法，使用不同含量（0.5-5 wt％）的铁和铬对ZSM-5进行了金属改性。比较了金属改性的ZSM-5样品，并研究了金属负载量对理化性质和催化性能的影响。Fe和Cr的改性对催化剂的物理化学性质以及催化活性和选择性都有影响。金属负载导致比表面积的减小，该比表面积随着金属负载的增加而进一步减小。与铬相比，铁对总酸度（特别是强酸部位）的影响更大。确定了最佳的Fe负载量，其提高了对烯烃，特别是丙烯的选择性。Fe还对P / E比具有显着影响，其中P / E比达到显着的5，并且增强了催化剂的稳定性。发现Cr是对BTX产物的选择性的良好促进剂，与Fe改性的催化剂相比观察到的增加了两倍。