Facile preparation of PtSn-La/Al2O3 catalyst with large pore size and its improved catalytic performance for isobutane dehydrogenation

Al2O3 beads with various pore sizes were successfully synthesized by combining ammonium alginate assisted sol-gel and emulsion template methods using liquid paraffin as pore-enlarging agent and polysorbate 80 as dispersant The great influences of textural structure of Al2O3 beads on the activity and stability of PtSn-La/Al2O3 catalyst for isobutane dehydrogenation were investigated by N-2 adsorption-desorption, XRD, NH3-TPD, SEM, HRTEM, H-2-TPR, XPS, isobutene transient response experiment and TG analysis. The results showed that Al2O3 beads with tunable pore sizes (7.4-133 nm), surface areas (294-322 m(2)/g) and pore volumes (0.56-1.1cm(3)/g) could be obtained by changing the addition amount ofliquid oil. Moreover, the transient response experiment stated that the PtSn-La/Al2O3 catalysts with large pore sizes could enhance the diffusion speed of the gas molecule in the channels. With increasing the amount of liquid oil from 0 to 20%wt, the particle sizes of platinum decreased from 2.86 nm to 1.45 nm, the amount of carbon deposit declined by 30.6% and the final yield of isobutene increased from 42% to 48%. The enhancement of catalytic performance of PtSn-La/Al catalyst with larger pore size was related to its smaller Pt particles, lower surface acidity and diffusion resistance of reaction products in the pore. (C) 2017 Elsevier B.V. All rights reserved.