Research On Elimination Of CO And Preparation Of Nanogold Catalyst

Mesoporous material SB A-15 has regular pore structure, large specific surface area and thermal stability. M-SBA-15, AuM-SBA-15 and Au-SBA-15 were prepared by surface modification method, and were applied to CO catalytic oxidation as catalysts.The mesoporous silica SBA-15 was modified by in-situ homogeneous precipitation method. Ni, Mn, Cu and Ag were supported on the inner surface of SBA-15, using corresponding metal nitrate as precursor, and the resulting materials were characterized by N2 adsorption-desorption and ICP. Using the modified SBA-15 as support and common HAuCl4 as precursor, AuM-SBA-15 (M=Ni, Mn, Cu and Ag) with 2% nominal gold loading in mass ratio were prepared by in-situ reduction method. The catalytic performance of M-SBA-15 and AuM-SBA-15 was evaluated in CO oxidation and the properties of the samples were characterized by N2 adsorption-desorption, XRD and ICP. The metal oxide and gold particles were well dispersed in the channel of SBA-15. Ni-SBA-15, Mn-SBA-15 and Cu-SBA-15 did not show low temperature CO catalytic oxidation activity. Ag-SBA-15 showed good low temperature CO catalytic oxidation activity, reproducibility and high temperature resistance to sintering. The CO catalytic oxidation activity of AuNi-SBA-15, AuMn-SBA-15 and AuCu-SBA-15 showed improvement significantly in comparison with Ni-SBA-15, Mn-SBA-15 and Cu-SBA-15 respectively except for Ag-SBA-15. Due to the weak interaction of gold and support, gold particles sintered during catalyst test, and thus the CO catalytic oxidation activity of the second cycle decreased in contrast with the first cycle.The gold catalyst was prepared by a facile deposition-precipitation method, and the effect of pretreatment conditions and gold loading on catalytic performance was studied. Properties of the samples were characterized by HR-TEM (high resolution transmission electron microscopy), N2 adsorption-desorption, XRD (X-ray diffraction), UV-vis DRS (ultraviolet visible diffuse reflectance spectrum), XPS (X-ray photoelectron spectroscopy) and ICP (inductively coupled plasma atomic emission spectroscopy). The gold particles were well dispersed in the channel of SBA-15 after pretreatment. The sintering of gold particles was inhibited by the nano-confined effect, and the difference of the diameter of gold particles caused by different pretreatment conditions affected the catalytic activity significantly. The sample pretreated with reduction and subsequent calcination exhibited high low-temperature activity and high catalytic activity when the reaction temperature was as high as 500℃, and showed good cycle stability and high resistance to sintering.