Catalytic performance of methanol decomposition on Cu/SiO₂ catalyst with different silica sources prepared with ammonia evaporation method

Cu/SiO₂ catalysts were prepared via ammonia evaporation method, using fumed silica (SiO₂-aer), silica gel (SiO₂-gel) and alkaline silica sol (SiO₂-sol) as the silica sources and their catalytic performance in methanol decomposition were investigated. The catalysts were characterized by N₂ adsorption-desorption, N₂O chemisorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), H₂ temperature programmed reduction (H₂-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that silica source can affect the decomposition activity of Cu/SiO₂ catalysts. The Cu/SiO₂-sol catalyst prepared with alkaline silica sol exhibits larger surface area, smaller active site size and more uniform dispersion of Cu. Therefore, it gives Cu/SiO₂-sol a better decomposition performance than other catalysts. Methanol conversion on Cu/SiO₂-sol is 10% higher than that on Cu/SiO₂-aer, and 7% higher than that on Cu/SiO₂-gel. Additionally, byproducts concentration on Cu/SiO₂-sol is considerably lower than other catalysts. Under the reaction conditions of 280 ℃, 1 MPa and 0.6 h^-1 of WHSV, methanol conversion of 98.4% and gas yield of 96.7% can be achieved.