Preparation of CuWO₄ foam and its use as a heterogeneous catalyst for dimethyl sulfoxide oxidation in a scale-up microreactor

Background: Metal foam has been demonstrated numerous advantages in fine chemistry when used as catalyst support. In this research, a novel strategy for the fabrication of copper tungstate (CuWO₄) foam as heterogeneous catalysis to conduct dimethyl sulfoxide (DMSO) oxidation reaction in a scale-up microreactor was proposed. Methods: A series of three-dimensional skeleton CuWO₄ foams were prepared by a continuous sintering approach. The obtained CuWO₄ catalysis inherited the porous structure from the copper foam and had a high loading density of CuWO₄ crystal particles. Afterwards, DMSO oxidation was employed as a probe reaction to explore the catalytic performance of CuWO₄ foam. Significant findings: CuWO₄ foam showed prefect catalytic activity in a scale-up microreactor. The average crystallite size of CuWO₄ were increased from 52.8 to 57.7 nm with extension of sintering time. Under the optimum condition (residence time was 40 min, CuWO₄ catalyst was CuWO₄F-5 and reaction temperature was 80 ^oC), a high dimethyl sulfone yield of 65.4% was obtained. The yield of MSM reached nearly 65.3% in the run time of 1 h and showed a value of 50.4% even in the run time of 4 h. Higher reaction contact surface and larger crystal particles of CuWO₄ foam are conducive to enhancing the catalytic performance of CuWO₄ foam. This research indicates the potential opportunity to apply CuWO₄ foam in a scale-up microreactor.