The effect of Brønsted acidity of WO3/ZrO2 catalysts in dehydration reactions of C3 and C4 alcohols

• Brønsted acidity can be controlled by introduction of WO3 content.
• Brønsted acidity was well correlated with the TPD results for C3 and C4 alcohols.
• Brønsted acidity critically influences for conversion of C3 and C4 alcohols in dehydration.
• In IPA dehydration, propene selectivity correlates with increasing Brønsted acidity.
• In IBA and nBA dehydration, Brønsted acidity did not affect initial selectivity to cis-2-butene.

WO3/ZrO2 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% WO3 content in the range of 0–30 wt% WO3/ZrO2 catalysts. In IPA dehydration, conversion and selectivity to propene were well correlated with Brønsted acidity. In the dehydration of nBA and IBA, conversion was also influenced by Brønsted acidity. However, product selectivity to iso-butene, 1-butene, cis-2-butene (c-butene), and trans-2-butene (t-butene) was not affected by Brønsted 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.

Figure optionsDownload as PowerPoint slide