Facile fabrication of a superior Cu(I)-NH4Y zeolite adsorbent for improving thiophene adsorption selectivity in the presence of aromatics or olefins

摘要

Cu modified Y zeolite adsorbents have performed excellent adsorption desulfurization performance. Adsorption selectivity of thiophenic sulfur compounds, however, still remained a lower level in the presence of aromatics and olefins. In this work, we aim to address the above challenge, using Cu(I)-NH4Y zeolites obtained by liquid phase ion-exchanged method. Based on the coordination chemistry theory, the new adsorption active sites ([Cu+center dot center dot center dot NH3 center dot center dot center dot H+] species) can be facilely fabricated at lower temperature (ca. 150 degrees C) and under H-2 atmosphere. The desulfurization experimental results indicate that the outstanding breakthrough sulfur capacity (ca. 31.0 mg (S) center dot g(-1)) can be achieved by the Cu(I)(0.10)-NH4Y adsorbent, which is about 2.3 folds as high as the best one reported. After regeneration with three cycles, the adsorbent still remains a high sulfur capacity. Importantly, the thiophene adsorption selectivities of adsorbent have been improved in the presence of aromatics or olefins, which are about 44.5% and 6.3%, respectively. Meanwhile, the direct "S-M" bonding mechanism between thiophene and [Cu+center dot center dot center dot NH3 center dot center dot center dot H+] species can be really proposed. Besides, the alkylation reaction between thiophene and olefins is significantly attenuated, mainly ascribed to the majority of strong Bronsted acid sites being masked. The new design idea of effective active sites in the zeolite adsorbents breaks out the traditional high temperature preparation concept of excellent desulfurization adsorbents and can provide a new direction in the future.