Catalytic Pyrolysis of Coffee Grounds Using NiCu-Impregnated Catalysts

Abstract

NiCu/γ-Al2O3 catalysts with different Cu loadings were prepared using an ultrasonic-assisted impregnation method. The effect of the Cu content in the catalyst on the mass loss behavior of coffee grounds and the evolution of gaseous products during pyrolysis were investigated. The effect of two different heating rates of 10 and 60 °C/min on the catalytic pyrolysis was also studied. The mass loss and evolution of the main pyrolytic volatiles were analyzed with a thermogravimetric (TG) analyzer connected to a Fourier transform infrared (FTIR) spectrometer. The bio-oils collected from non-catalytic and catalytic pyrolyses of coffee grounds were subjected to gas chromatography–mass spectrometry (GC–MS) analysis. Gram–Schmidt curves obtained by TG–FTIR indicated that the addition of NiCu/γ-Al2O3 catalysts and the increase in the Cu content in the catalysts increased the concentrations of CO2 and CO in the produced gas evolved during coffee grounds pyrolysis. In comparison to the slow heating rate of 10 °C/min, ...