Catalytic aldol condensation of formaldehyde with acetic acid on titanium phosphates modified by different techniques

Autor: Volodymyr Ivasiv, Zoryan Pikh, S. Khalameida, Roman Nebesnyi, Karolina Kucio, Barbara Charmas, Yu. Nebesna, V. Sydorchuk, Iryna Shpyrka
Rok vydání: 2018
Předmět:
Zdroj: Reaction Kinetics, Mechanisms and Catalysis. 125:807-825
ISSN: 1878-5204
1878-5190
DOI: 10.1007/s11144-018-1443-8
Popis: X-ray amorphous titanium phosphate (TiP) prepared via precipitation from titanylsulfate showed low catalytic performances in the process of aldol condensation of acetic acid with formaldehyde for production of acrylic acid (AA). As-precipitated TiP was modified in the form of wet gel and dried xerogel using hydrothermal (HTT), microwave (MWT) and mechanochemical (MChT) treatments. The physical–chemical characteristics of initial and modified TiP were studied using XRD, FTIR, adsorption–desorption of nitrogen, ammonia thermo-programmed desorption. All types of treatment lead to significant but irregular changes in crystal and porous structure as well as surface acidity of TiP catalysts. The crystalline titanium hydro- and pyrophosphates are formed under hydrothermal conditions (HTT and MWT). These phases exhibit increased activity and selectivity with respect to acrylic acid. The formation of meso-macroporous structure also contributes to this. The most efficient catalyst contains crystalline titanium hydro- and pyrophosphates and has high total acidity with maximum content of strong acid sites, multimodal meso-macroporous structure and the highest share of macropores: AA yield on this catalyst is 61% at 80% acrylic acid selectivity. It can be prepared via HTT of xerogel at 300 °C.
Databáze: OpenAIRE
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