乙苯脱氢制苯乙烯工业催化剂的失活原因

Deactivation of the Industrial Catalyst for Ethylbenzene Dehydrogenation to Styrene

用混合法制备了工业乙苯脱氢催化剂,考察了新鲜催化剂和使用34个月后的催化剂的催化性能,并应用多种表征手段详细研究了所制备的工业催化剂在使用前后体相和表面的变化情况.活性测试结果发现,催化剂使用34个月后,活性下降12%,消炭后催化剂活性有所提高,但很快又恢复到失活后的水平.表征结果发现,积炭、钾的流失和催化剂活性相的烧结都不是导致催化剂失活的根本原因,而助催化剂钾的不均匀分布和催化剂活性相中Fe3+的还原可能是催化剂失活的主要原因.

The deactivation of the prepared industrial Fe-K catalyst for ethylbenzene dehydrogenation to styrene was characterized by X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction, and Moessbauer spectroscopy. The activity of fresh and spent catalyst samples was evaluated in a fixed-bed reactor. The results showed that regeneration of the spent catalyst by coke burning could improve activity, but the activity was reduced to the level of the spent catalyst after a short time of reaction. The characterization results indicated that coke deposition, catalyst sintering, and potassium loss were not responsible for the catalyst deactivation. However, the migration and uneven redistribution of potassium and reduction of Fe^3 ＋ were the major reasons for the deactivation.