Synthesis, characterization of metal containing silica micro-spheres and investigation of their activities

In this study, it is aimed to develop coke formation sensitive catalysts as a result of active, selective, sustainable, reaction to hydrogen and carbon monoxide as chemical product which can be used with dry reforming of methane reaction. For this purpose, monometallic Ni, bimetallic Ni-Co, Ni-Fe and Ni-Pd silica microspheres were prepared by sol-gel microencapsulation and sol-gel microencapsulation-impregnation synthesis methods. The catalysts determined to be 5% Ni-M (M: Co, Fe, Pd) will be equal Ni-M, low Ni-high M and high Ni-low M (1Ni-1M, 1Ni-2M, 2Ni-1M and 4Ni-1M) based on the activity and stability results of different Ni-based mono metallic silica microsphere catalysts. In order to determine the physical and structural properties of the prepared catalysts, ICP-OES, N2 adsorption-desorption, XRD and SEM analyzes were performed. For the dry reforming of methane reaction, the appropriate reaction temperature was determined as 750 ˚C and the feed rate was determined as CH4/CO2/N2: 1/1/1. The effect of determined optimum conditions on the catalytic activity of catalysts was investigated. In the catalytic activity experiments carried out in the presence of total 5% metal-containing bimetallic microsphere catalysts, 1Ni-2Pd sol-gel microencapsulation-impregnation bimetallic silica microspheric catalyst showed the maximum activity (88 % methane) and maximum H2/CO ratio (0,92). In addition to the Ni-Pd loaded bimetallic silica microspheres, Ni-Co loaded bimetallic silica microspheres were found to be very active for this reaction from activity tests and were stable for 3 hours. SEM, XRD, TGA and Raman spectroscopy analyzes were performed in order to determine the structural and physical changes of the catalysts after the reaction. Coke formation was observed in the Ni-Fe bimetallic silica microsphere catalysts after the reaction. Coke formation was not detected in the structures of Ni-Co and Ni-Pd bimetallic microspheres. Ni-Pd and Ni-Co bimetallic silica microspheres showed the highest activity, stability and H2/CO ratio. Coke formation and activity loss were not detected for these catalysts during 12 hours long life activity tests.