Preparation of silica-supported copper catalysts by means of deposition-precipitation

Silica-supported copper catalysts have been prepared by means of deposition-precipitation under both atmospheric and hydrothermal conditions. Characterization of the catalyst precursor indicates the formation of a highly dispersed copper hydrosilicate with structural properties similar to the mineral chrysocolla. Increasing the metal loading from 5 to 40 wt.-% causes the specific surface area of the catalyst precursors to rise from 210 to 520 m2/g. The precipitation conditions affect both the reduction behavior and the texture of the catalyst precursors. Hydrothermal synthesis gives rise to formation to chrysocolla-like catalyst precursors, which exhibit a decreased ease of reduction and a higher pore volume, Due to the formation of a copper hydrosilicate of a high specific surface area, this preparation method facilitates the formation of highly dispersed copper-on-silica particles in the reduced catalyst, even at elevated metal loadings. After reduction, the catalysts show a mean metal particle size gradually increasing from 3 to 8 nm as the metal loading increases.