Synthesis & Characterization of Au-promoted NiMo/Al2O3 Catalysts

Sammanfattning

The phasing out of fossil fuels continues to be of great importance if our society is to complete the green transition. One of the most interesting alternatives to fossil fuels is bio-fuels but these have not been shown to outperform fossil fuels in all areas, as of yet. This is especially true in applications that require high performance and have high safety standars, such as the aviation industry. To improve the performance of bio-fuels one looks to their upgrading and in thisthe Hydrodeoxygenation reaction (HDO) is an important step. The HDO reaction is a catalyzed reaction that removes oxygen from the biomass and produces variety of organic compounds. The removal of oxygen from the fuel feedstock improves its’ combustion efficiency and is therefore of great importance. To catalyze the HDO reaction Nickel-Molybdenum supported on Al2O3 is used. Lately, there have been research into further promotion of these catalysts, in the hope of developing new properties which could enhance the HDO reaction in both selectivity, efficiency and reaction temperature. Along the same lines of thought, gold has also shown interesting catalytic properties in other catalysts as a promotor. The promotion of NiMo/Al2O3 with gold is therefore interesting. Au-promoted Ni, Mo and NiMo catalysts supported on Al2O3 were all synthesized with a incipient wetness method (IWI). This was followed by measurements off their reduction characteristics with temperature programmed reduction (TPR), pore measurements by N2-physisorption using the Brunnauer-Emmett-Teller method (BET) and surface imaging and quantification with Scanning Electron Microscopy – Energy Dispersive Spectroscopy (SEM-EDX). It was found that by dividing the gold impregnation into three parts, relatively good Au dispersion on the support was acquired. It was also shown that gold does impact the reduction characteristics of NiMo/Al2O3 even at low Au-loadings, leading to some MoO3 being reduced at lower temperatures compared to the unpromoted catalyst. In conclusion, gold was shown to have promising properties as a catalyst promoter which further studies would shed light on.