The effect of Broensted acidity of WO sub(3)/ZrO sub(2) catalysts in dehydration reactions of C3 and C4 alcohols

WO sub(3)/ZrO sub(2) catalysts were synthesized by an excess solution impregnation method, and its applications for the dehydration of iso-propanol (IPA) and n-butanol (nBA) and iso-butanol (IBA) as C3-C4 alcohols were investigated. The catalytic activity was maximized at 20 wt% WO sub(3) content in the range of 0-30 wt% WO sub(3)/ZrO sub(2) catalysts. In IPA dehydration, conversion and selectivity to propene were well correlated with Broensted acidity. In the dehydration of nBA and IBA, conversion was also influenced by Broensted acidity. However, product selectivity to iso-butene, 1-butene, cis-2-butene (c-butene), and trans-2-butene (t-butene) was not affected by Broensted acidity. Below 85% conversion in IBA dehydration, the ratio of cis/trans isomer in 2-butenes was almost constant. However, above this range of conversion the catalytic isomerization of iso-butene to t-butene is accompanied with slight deactivation of catalysts with time on stream. In the nBA dehydration the catalytic isomerization of t-butene to 1-butene changes the cis/trans ratio in the formation of 2-butenes resulting that below unity in initial period, and gradually increased as the reaction proceeds.