Tuning of the textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acid catalysts for alkenylation of diverse aromatics to their corresponding α-arylstyrenes

Abstract

The textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acids (SO42−/meso-La0.1Zr0.9Oδ) were efficiently tuned by modifying the conditions used to prepare the meso-La0.1Zr0.9Oδ composites, such as the molar ratio of the template to La and Zr metal ions (Nt/m), molar ratio of ammonia to La and Zr metal ions (Na/m), hydrothermal temperature (Thydro), and hydrothermal time (thydro). The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p-xylene with phenylacetylene was investigated. Various characterization techniques such as N2 physisorption, X-ray diffraction, NH3 temperature-programmed desorption, and thermogravimetric analysis were employed to reveal the relationship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso-La0.1Zr0.9Oδ composite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t-ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42−/meso-La0.1Zr0.9Oδ catalyst exhibited much superior catalytic activity and coke-resistant stability. Moreover, the developed SO42−/meso-La0.1Zr0.9Oδ catalyst demonstrated excellent catalytic performance for alkenylation of diverse aromatics with phenylacetylene to their corresponding α-arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42−/meso-La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production of α-arylstyrenes through clean and atom efficient solid-acid-mediated Friedel-Crafts alkenylation of diverse aromatics with phenylacetylene.