Investigating the Effect of Operational Variables on the Yield, Characterization, and Properties of End-of-Life Olive Stone Biomass Pyrolysis Products.

In recent years, biomass has emerged as a promising raw material to produce various products, including hydrocarbons, platform chemicals, and fuels. However, a more comprehensive evaluation of the potential production of desirable value-added products and chemical intermediates is required. For these reasons, this study aimed to investigate the impact of various operating parameters on the pyrolysis of end-of-life olive stone, an agriculture and food industry waste, using a tubular quartz reactor operated at 773 K. The results revealed that the product compositions were comparable under batch or semi-batch nitrogen feeding conditions and with reaction times of 1 or 3 h. The product distribution and composition were significantly influenced by changes in the heating rate from 5 to 50 K min-1, while the effect of changing the biomass particle size from 0.3 to 5 mm was negligible in the semi-batch test. This work provides a comprehensive understanding of the relationship between pyrolysis operational parameters and obtained product distribution and composition. Moreover, the results confirmed the possible exploitation of end-of-life olive stone waste to produce high-added value compounds in the zero-waste strategy and biorefinery concept.

Graphene-Based Material Supports for Ni- and Ru- Catalysts in CO2 Hydrogenation: Ruling out Performances and Impurity Role.

Laboratory-prepared Gnp using molten salt, commercial Gnp and reduced graphene oxide (rGO) have been characterized and utilized as support for CO2 hydrogenation catalysts. Ni- and Ru- catalysts supported over Gnp, commercial Gnp and rGO have been deeply characterized at different stages using Raman, IR, XRD, FE-SEM-EDXS, SEM-EDXS, XPS, and TEM, also addressing carbon loss before reaction and evolved species, thus allowing a better comprehension of the produced materials. Ni and Ru/rGO were inactive while Gnp-supported ones were active. Ru has been found almost completely selective toward reverse Water Gas Shift to CO, approaching the forecasted thermodynamic equilibrium at 723 K, in the tested conditions (YCO~55 %), with an apparent activation energy in the range of 70-90 kJ/mol. Exhaust catalysts pointed out the presence of sulfur partially linked to the carbon matrix and partially producing the corresponding metal sulfide with the detection of surface oxidized species in the cationic form and adsorbed species as well. The metal-based nanoparticles displayed a quite narrow size distribution, confirming the promising behavior of these catalytic systems for CO2 utilization.

Reutilization of silicon- and aluminum- containing wastes in the perspective of the preparation of SiO2-Al2O3 based porous materials for adsorbents and catalysts.

The waste materials available as sources of silicon and aluminum for producing porous materials like amorphous silicas, aluminas, amorphous silica-aluminas, and zeolites, to be used as catalyst and adsorbents, are briefly summarized. The procedures for preparing these materials from wastes are also taken into account. The limits of this approach in terms of economy and environmental protection are also briefly considered. It is concluded that mesoporous materials can be prepared from wastes, but care to product quality and to overall process efficiency is needed.