Pyrolysis kinetics and physicochemical properties of agropellets produced from spent ground coffee blended with conventional biomass

• Agropellets were produced from pure spent coffee grounds (SCG) or blended with pine sawdust.
• Chemical and physical characteristics and energy contents of the obtained agro-pellets were determined.
• Thermorgavimetric analyses were performed under inert and oxidative atmosphere.
• Kinetic parameters of the different agropellets thermal degradation are obtained.
• The use of blend sawdust/SCG may be an attractive biofuel.

Spent coffee grounds (SCG), a processing by-product from the coffee industry, were evaluated as a potential feedstock for preparing agropellets for energy production. Hence, pure SCG and a SCG/sawdust blend were transformed into pellets. The latter thermal and chemical properties such as calorific value, ash content, bulk density, fixed carbon and elemental analysis were obtained. Thermogravimetric analyses were conducted in order to determine pyrolysis kinetics and combustion characteristics in order to study the agropellets performance.The obtained results show that SCG pellets thermal characteristics are in the same order as conventional biomasses such as sawdust. Moreover, blend 50% SCG/50% sawdust reaches the superior NF agropellets standard requirements which are essential to sell this agropellets in the French market. Analysis of the thermal degradation shows that SCG and its blend follow the usual behavior of lignocellulosic materials. Comparison of the combustion characteristics shows a higher reactivity of the blend comparing to pure SCG and sawdust. Such behavior might relate to heterogeneous structure and mutual interaction of the individual components of SCG and sawdust. Pyrolysis kinetics parameters obtained for SCG and SCG/sawdust blend are fairly close agreement with those found in literature for different biomasses. Hence SCG/sawdust may be a promising biofuel for the energy production in industrial applications.