Effect of surface acidity-basicity balance in modified ZnxZryOz catalyst on its performance in the conversion of hydrous ethanol to hydrocarbons

ZnxZryOz and modified MuZnxZryOz (M = Si, W, Sc, Mg)/ Zn/(W-Zr) catalysts were studied in conversion of hydrous (4 wt% H2O) ethanol at P =15 bar, T = 450 degrees C and WHSV = 0.8-7.9 h(-1). The basicity of the catalysts changed from 0.015 to 0.66 mmol/g and the acidity from 0.07 to 0.24 mmol/g resulting in a wide range of basicity/acidity ratio (R) of 1.3 to 7.3. Measurements of the catalysts activity, selectivity and stability indicate a strong dependency on the R-value. The yield of organic liquid C-5-C-11 increased from 17 wt% to 59 wt% while the yield of light olefins C-2-C-4 decreased from 60 wt% to 14 wt%, as R increased from 1.3 to 7.3. The content of C-5-C-11 iso-olefins and aromatics in organic liquid on ZnxZryOz (R = 3.9), WuZnxZryOz (R = 2.0) and MguZnxZryOz (R = 7.3) increased significantly with the residence time. ZnxZryOz was stable up to 360 h on stream, while the activity and selectivity of MguZnxZryOz and WuZnxZryOz altered after 90 h on stream due to coke deposition blocking the acid and basic sites. It was proposed a comprehensive scheme of ethanol transformations routes consistent with the measured effects of the residence time, catalysts R-value and time on stream on the products distribution. (c) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The basicity/acidity ratio of the catalysts has a significant impact on the yield of organic liquid C5-C11 and light olefins C2-C4, with an increase in residence time resulting in a significant increase in the content of iso-olefins and aromatics in the organic liquid.