Abstract:

In order to exclude the effect of pore structure of carrier, effect of modification of α-alumina with titania on catalytic performance of silver catalyst for ethylene selective oxidation reaction was studied carefully. Experimental results showed that the specific surface area and the pore structure of the carriers were almost unchanged after modification with titania, but silver was dispersed more evenly on the modified carrier than on the α-alumina and the interaction discovered stronger between the modified carrier and silver than between α-alumina and silver. Modification of alumina with titania deteriorates the catalytic performance and was unfavorable to the performance of non-promoted silver catalysts. But it was beneficial to the catalytic performance of the promoted silver catalysts prepared by co-impregnation method. Research results revealed that decrease of IEP (isoelectric point) for the modified carrier and the strong interaction between the carrier and silver are responsible for the even and good dispersion of silver on the modified carrier. In presence of promoters, the interaction between the carrier and silver is weakened and the oxidation and isomerization side-reactions of ethylene oxide are abated, which jointly improve the catalytic performance of the promoted silver catalyst.

Key words: titania, modification, alumina, support, silver, catalyst, ethylene oxide