The Co-promotion effect of Mo and Nd on the activity and stability of sulfated zirconia-based solid acids in esterification

SO 4 2− /ZrO 2 –MoO 3 (SZM), SO 4 2− /ZrO 2 –Nd 2 O 3 (SZN) and SO 4 2− /ZrO 2 –MoO 3 –Nd 2 O 3 (SZMN) solid acids catalysts were prepared and characterized by XRD, NH 3 -FTIR, NH 3 -TPD and TG–DTG. The activities and stabilities of the catalysts for the esterification of fatty acids were investigated. Experimental and characterization results show that the excellent activity and stability of SZMN are attributed to the firm combination of sulfur species with t -ZrO 2 . The co-addition of Mo and Nd increases the dispersion of t -ZrO 2 and stabilizes the structure of small-crystallite t -ZrO 2 , which is favorable to increasing the acid sites amount, strengthening the acidity, and then enhancing the activity and stability of the catalyst.