MgO-containing porous carbon spheres derived from magnesium lignosulfonate as sustainable basic catalysts

• Published in: Journal of environmental chemical engineering Vol. 11; no. 1; p. 109060
• Main Authors: García-Rollán, M., García-Mateos, F.J., Ruiz-Rosas, R., Rosas, J.M., Rodríguez-Mirasol, J., Cordero, T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2023
• Subjects: Activated carbon; Basic catalyst; CO2 gasification; Dehydrogenation; Lignin; Magnesium nanoparticles; Lignin; Magnesium nanoparticles; Basic catalyst; Dehydrogenation; Activated carbon; CO2 gasification
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2022.109060

The presence of alkalis in lignosulfonate allows an easy preparation of sustainable MgO-containing carbon catalysts with surface basicity by carbonization of magnesium lignosulfonate and/or further partial gasification of the produced char with CO2. Carbon spheres with different chemical and physical properties were obtained from lignosulfonate treated at temperatures ranging from 500 to 900 ºC. Carbonization at 900 °C generates hollow porous carbon spheres (pore volume of 0.20 cm3/g and apparent surface area of 465 m2/g) with magnesium content of 12%. A kinetic study of CO2 gasification of the carbon spheres obtained at 900 °C at temperatures in the range of 700 – 800 °C revealed that the gasification rate can be accurately described by the random pore model up to conversion values of 0.5. Based on this study, in order to develop additional porosity on the carbon spheres obtained at 900 °C, a partial gasification with CO2 at 750 °C for 30 min was carried out, reaching surface areas higher than 700 m2/g and 15.3% of Mg loading, with an overall preparation yield of 30%. All the obtained carbon materials were tested as catalyst for 2-propanol decomposition, showing a high selectivity to acetone, evidencing the basic character of these carbon catalysts. The highest activity and selectivity were shown by the CO2-activated carbon spheres (conversion and acetone selectivity higher than 90% at 420 °C), indicating that magnesium lignosulfonate is an attractive raw material for the preparation of sustainable carbon catalysts for biorefinery applications. [Display omitted] •Easy preparation of sustainable MgO basic catalysts from lignosulfonate.•Carbonization produces hollow carbon spheres with high alkali content (Mg, K, Ca).•CO2 Gasification increases 50% the ABET showing high preparation yield (30%).•Activated carbon with 15.5 wt% Mg and well-dispersed MgO nanoparticles (7–10 nm).•High alcohol dehydrogenation activity with outstanding acetone selectivity.