The two catalysts were selected based on their distinctly differenttextural and surface properties. More specifically, the catalyststested were an acidic commercial equilibrium ZSM-5 zeolitediluted with silica-alumina (containing 30 wt.% crystalline zeolite)and a basic magnesium oxide (MgO), which was producedindustrially via calcination of natural magnesite at temperaturesbetween 700 and 1100 C (Grecian Magnesite S.A.). The ZSM-5 based catalyst had a surface area of 127 m2/g (determined by theBET analysis of the N2 adsorption data at 77 K), total number ofacid sites 0.14 mmoles NH3/g (determined by temperature programmeddesorption of ammonia-TPD/NH3 experiments), andBrönsted to Lewis acid sites ratio of 1.8 (determined by FT-IRspectroscopy coupled with in situ adsorption of pyridine)(Iliopoulou et al., 2012, 2014). The MgO catalyst had a surfacearea of 62 m2/g and exhibited negligible acidity (i.e. <0.01 mmolesNH3/g, all of which was attributed to Lewis sites as verified byFTIR-pyridine sorption measurements). On the other hand, theMgO catalyst contained basic sites (0.24 mmoles/g, as determinedby TPD-CO2).
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