Vapor-phase dehydration of C4 unsaturated alcohols to 1,3-butadiene

Abstract

Vapor-phase dehydration of C4 unsaturated alcohols such as 3-buten-1-ol, 2-buten-1-ol and 3-buten-2-ol were performed to produce 1,3-butadiene over various solid catalysts including ordinary solid acid catalysts such as Al2O3, SiO2-Al2O3, and TiO2 and basic rare earth metal oxides such as Yb2O3 and CeO2. In the reaction of 3-buten-1-ol, 1,3-butadiene could not be selectively produced because the acid catalysts decomposed 3-buten-1-ol into propylene. In contrast to the acid catalysts, CeO2 inhibited the decomposition of 3-buten-1-ol and showed a relatively high performance for the formation of 1,3-butadiene. In the dehydration of 2-buten-1-ol and 3-buten-2-ol, however, acid catalysts were effective for the formation of 1,3-butadiene. Among the tested catalysts, commercial SiO2-Al2O3 showed a relatively high catalytic performance, although it deactivated rapidly. We prepared a series of SiO2/Al2O3 catalysts by depositing SiO2 species onto Al2O3 support, and the SiO2/Al2O3 with a SiO2 content of 10wt.% showed more stable catalytic activity than the commercial SiO2-Al2O3. Furthermore, modification of SiO2/Al2O3 with Ag at a loading of 3–5wt.% was found to be efficient for inhibiting the coke formation and improving the catalytic stability of SiO2/Al2O3 in the dehydration of both 2-buten-1-ol and 3-buten-2-ol under hydrogen flow conditions.