Regeneration Performance Of CeY Sorbent Used For Removal Of Thiophene From Coking Benzene

Coking benzene is an important chemical raw material, but the thiophene containing in it greatly limits its further utilization because of corroding metal equipment and pipeline, poisoning catalyst and polluting environment. It is quite necessary to deeply remove the thiophene from coking benzene. Adsorptive desulfurization technology can be used to removing sulfur in coking benzene for its advantages of simple operation, low energy consumption, low equipment investment and high desulfurization precision. For this technology, the regeneration of sorbent is one of the keys, so it is requirement to find a suitable regeneration process and investigate the desulfurization mechanism of sorbent. Based on our early study, CeY zeolite is considered as a good sorbent for the removal of thiophene from benzene.For this purpose, the CeY zeolite adsorbed the pure thiophene (TY) was firstly regenerated by the thermal regeneration method. The effects of regeneration temperature on the regeneration behavior of TY sample in Ar, H2, O2and air atmosphere were investigated, and the regeneration mechanism was also preliminary discussed in different atmosphere and temperature by the characterization of TG-DTG, MS, analysis of carbon and sulfur on the surface of sorbent, etc. The results show that TY can be well regenerated in air at500℃, and its desulfurization efficiency can reach up94.02%after regenerated, which is94.67%of fresh adsorbent. The content of carbon and sulfur in regenerated TY has a great influence on its desulfurization performance. The low temperature can not reasonably regenerate TY sample due to its high content of carbon and sulfur, while the high temperature may disrupt the structure of sorbent, which are unfavorable for the adsorption of thiophene from benzene. The structure of the sorbent regenerated in pure O2is seriously destroyed, and the removing of sulfur is favorable when sorbent is regenerated in H2atmosphere. The products released in the process of sorbent regeneration in Ar are basically the same in air, but the desorption temperature interval and product quantity are very different. TY sorbent presents the best regeneration performance in air atmosphere.Base on the above, the effects of regeneration temperature, space velocity, oxygen content and regeneration time on the regeneration of CeY sorbent adsorbed thiophene in benzene (TBY) were further studied, and the regeneration conditions were optimized. The results show that the regeneration temperature is the main influencing factors for the regeneration of TBY sample, and the space velocity, oxygen content and regeneration time have little effect on desulfurization performance of regenerated TBY sorbent. The best regeneration conditions of TBY sample are air atmosphere with the space velocity of1000h-1 at500℃for1h, in which the desulfurization efficiency of TBY can reach up96.44%.Finally, the adsorption-regeneration experiment by fixed bed reactor was used to evaluate the regeneration performance of TBY under the optimized regeneration conditions. The results show that the breakthrough adsorption capacity of CeY sorbent still can reach72.00%of the fresh sorbents after three cycle adsorption-regeneration. The content of carbon and sulfur in sorbent is still the main unfavorable factors of the desulfurization process.