Pt-Sn-碱/r-Al_2O_3催化剂中氯和碱含量对戊烷脱氢的影响

EFFECT OF CHLORINE AND ALKALI METAL ON THE ACCTIVITY AND SELECTIVITY OF DYHYDROGENATION

以Pt-Sn/r-Al_2O_3工业催化剂为基础.考察了催化剂中氧及碱金属助剂含量对正戊烷脱氩活性和选择性的影响规律.阐明了脱氢活性、选择性及催化剂抗积炭能力与催化剂表面酸性的依赖关系.研究结果表明,添加一定含量的碱助剂可明显调变催化剂表面强酸中心,有效地抑制催化剂上的酸性反应,使脱氢活性有所加强,进而显著地提高催化剂的脱氢选择性和抗积炭能力.基础催化剂脱氯后再添加碱金属,可获得类似效果。

The effect of chlorine and alkali metal on the activity and selectivity of pentane dehydrogenation was studied in microreactor-chromatograph apparatus with Pt-Sn /γ-Al2O3 catalyst as base catalyst. The effect of alkali metal on the acid sites and the amount of carbon deposits on catalyst surface was also investigated by pyridine-IR and elemental analysis. The results show that the role of alkali metal is to modify the strong acid sites and to inhibit side reactions promoted by these acid sites. Therefore the dehydrogenation reaction can be enhanced and the dehydrogenation selectivity increased with reduced carbon deposits on catalyst. Similar results were found by dechlorination of the catalyst, as its chloring content was reduced from 1. 11% to 0. 16%.