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<p>A series of bismuth molybdate catalysts were synthesised at different pH via a hydrothermal method using citric acid. The calcined and uncalcined catalysts were tested for the selective oxidation of propene to acrolein under microwave-electric field heating and conventional heating. Under conventional heating the catalysts synthesised at low pH were found to give the best performance, however, under microwave heating the key parameter was the calcination step. The dielectric properties were determined using cavity perturbation methods and non-calcined samples were found to have a high dielectric loss tangent, a measure of how well a material can convert microwave radiation into heat, that was ascribed to residual water and nitrate ions in the catalysts. On calcination the residual water and nitrate was removed and the particle size increased leading to low dielectric loss tangents. When heated at low power (10–20&#xa0;W) the microwave-electric field the catalysts gave very high selectivity to acrolein compared to the conventionally heated catalysts at isoconversion. This was attributed to the microwave energy selectively heating the catalyst bed, but not the reactants, suppressing sequential oxidation and cracking reactions. This study demonstrates the importance of both the materials dielectric and catalytic properties in microwave-assisted catalysis which allows high yields to be achieved when compared to the same catalysts under conventional heating.</p>

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Microwave-assisted selective oxidation of propene over bismuth molybdate catalysts: the importance of catalyst synthesis methodology

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年6月23日

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  • Jia Sun,
  • James S. Hayward,
  • Michael Barter,
  • Daniel R. Slocombe,
  • Jonathan K. Bartley

摘要

A series of bismuth molybdate catalysts were synthesised at different pH via a hydrothermal method using citric acid. The calcined and uncalcined catalysts were tested for the selective oxidation of propene to acrolein under microwave-electric field heating and conventional heating. Under conventional heating the catalysts synthesised at low pH were found to give the best performance, however, under microwave heating the key parameter was the calcination step. The dielectric properties were determined using cavity perturbation methods and non-calcined samples were found to have a high dielectric loss tangent, a measure of how well a material can convert microwave radiation into heat, that was ascribed to residual water and nitrate ions in the catalysts. On calcination the residual water and nitrate was removed and the particle size increased leading to low dielectric loss tangents. When heated at low power (10–20 W) the microwave-electric field the catalysts gave very high selectivity to acrolein compared to the conventionally heated catalysts at isoconversion. This was attributed to the microwave energy selectively heating the catalyst bed, but not the reactants, suppressing sequential oxidation and cracking reactions. This study demonstrates the importance of both the materials dielectric and catalytic properties in microwave-assisted catalysis which allows high yields to be achieved when compared to the same catalysts under conventional heating.