Preparation and characterization of tungstated CexZr1-xO2@TiO2 solid superacid with promoting mass transfer

To form effective micro reaction locations in membrane, aminated lignin (AL) is used as porogen to enlarge channels of the ZrO2 shell for promoting mass transfer inside its shell, and cerium (Ce) is doped into ZrO2 crystal lattice to stabilize its tetragonal phase structure, and finally WO3/CexZr1-xO2 solid superacid coated TiO2 particles (WCZ-Tis) are fabricated via tungstate treatment. Moreover, the as-prepared WCZ-Tis are studied by SEM, TEM, XRD and BET. The results show that WCZ-Tis exhibit a typical porous core-shell structure. WCZ-Tis have a wider pore size distribution, and its mean pore size is expanded from 3.4 nm to 12.5 nm after removing AL. As for degrading methyl orange, the photodegradation efficiency of WCZ-Tis prepared by AL is 32.09%, showing 2.6-folds increase than that of WCZ-Tis prepared without AL (12.51%). Furthermore, the XRD diffraction peaks appear at 2θ = 30.15°, 35.28°, 50.38°, etc., meanwhile the peaks of monoclinic (2θ = 28.17°, 31.57°, etc.) or amorphous ZrO2 disappear after doping Ce confirming the formation of tetragonal ZrO2. Therefore, pore-expanding by AL is a feasible solution for enhancing the internal mass transfer of WCZ-Tis, while doping Ce indeed promotes the crystallization of tetragonal ZrO2 and stabilizes tetragonal ZrO2.