Sol-gel Ni/γ-Al2O3 material as secondary catalyst for toluene reforming: Tailoring the γ-Al2O3 substrate with stearic acid

Abstract

Abstract In this work, Ni-based catalysts supported on alumina were studied for toluene reforming with a particular attention on the substrate texture. Indeed, the influence of stearic acid addition during the synthesis process of Ni/Al2O3 catalysts was study on the material texture and catalytic activity. All the samples were also characterized thanks to nitrogen adsorption-desorption isotherm measurements, mercury porosimetry and X-ray diffraction. It was shown that the step of addition of the surfactant during the synthesis process and the composition of the solvent medium (water/ethanol vs. pure ethanol) strongly modified the texture of the samples. Indeed, the sample prepared with addition of stearic acid before the precipitation step and inside a pure ethanol medium showed the highest increase of micro- and mesoporosity. The modification of the textural properties also proved to influence the size of the Ni particles, and thus the reducibility of the catalysts. The sample which showed the most interesting textural properties was tested for the reforming of 24.000 ppmv of toluene at 650 °C. Results showed that the conversion of toluene strongly increased when the samples were tailored but these changes also increased the catalyst sensitivity to carbon contamination.