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

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)(2)P2O7 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.