Aldol condensation of acetic acid with formaldehyde to acrylic acid over Cs(Ce, Nd) VPO/SiO2 catalyst

Abstract

Cs, Ce, and Nd cation-modified VPO/SiO₂ catalysts were prepared by a deposition method. The VPO/SiO₂ catalyst was composed of VOPO₄ and (VO)₂P₂O₇ phases. When Cs, Ce, and Nd cations were added in the VPO/SiO₂ catalyst, Cs₄P₂O₇, CePO₄, and NdPO₄ were formed and V⁵⁺/V⁴⁺ ratio increased, respectively. The basicities of the metallic cation-modified catalysts increased while their acidities exhibited maximum values with the increase in the ratios of metallic cation to vanadium. The metallic cation-modified VPO/SiO₂ catalysts exhibited higher catalytic activities for the aldol condensation reaction of acetic acid with formaldehyde to acrylic acid than the VPO/SiO₂ catalyst. The high acidity and basicity of the metallic cation-modified VPO/SiO₂ catalysts favored the formation of acrylic acid.