Abstract: Niobium modified mesoporous molecular sieve catalysts were prepared by three methods: direct synthesis, post-synthesis and direct synthesis-oxalic acid treatment, the prepared catalysts were named as (Z)-Nb-SBA-15, (H)-Nb-SBA-15 and oxalic acid modified (Z)-Nb-SBA-15, respectively. These samples were characterized by XRD, BET, FT-IR and DTA techniques, and the results showed that the structure of (Z)-Nb-SBA-15 was varied from that of (H)-Nb-SBA-15. The catalytic performance of these catalysts was evaluated using synthesis of isopropyl oleate from isopropanol and leic acid as probe reaction. Evaluation results showed that (H)-Nb-SBA-15 had more reactive hydroxyl than (Z)-Nb-SBA-15, thus the catalytic activity of the former was higher than the latter, yet the stability of the latter was better than the former; the catalytic activity and stability of oxalic acid modified (Z)-Nb-SBA-15 were both improved.

Key words: Niobium, Nb-SBA-15, Esterification, isopropyl oleate