Gabriella Garbarino

Catalytic abatement of biomass tar: a technological perspective of Ni-based catalysts

Heterogeneous catalysis has a fundamental role in the development of both gasification and gas cleanup technologies for the production of synthesis gas (syngas) and renewable hydrogen. In this review, a technological perspective of Ni-based catalysts is presented giving particular attention to the interaction of different tars molecules present in tar mixture and to catalyst deactivation by coke deposition and sulphur poisoning. For the effective development of these technologies, several challenges have been still to be undertaken, so that, are outlined in this review: (i) optimization of catalyst formulation; (ii) catalyst stability; (iii) resistance to the different contaminants present in biomass feedstocks; (iv) activity in more complex mixtures, coupling the knowledge available with model mixture and evidence eventual interaction that might be detrimental in start-up and shut-down operations; (v) tests in real biomass tar and in pilot plants; (vi) determination of mechanisms and kinetics for the complex reaction network and coke deposition; and (vii) development of effective regeneration steps applicable in real industrial applications.

A study of ethanol conversion over zinc aluminate catalyst

The conversion of ethanol over a commercial ZnAl2O4 has been investigated. The catalyst has been fully characterized by XRD, IR, UV–Vis-NIR, ICP-OES, EDX-FE-SEM, BET and porosimetry. The catalyst is active in converting ethanol. At low conversion, diethyl ether is the main product while at higher conversions acetaldehyde is the main product (max yield ~ 50%). Ethylene and ethyl acetate are coproduced. Acetone and propylene become relevant products at complete conversion. The mechanism of formation of the products is discussed based on infrared surface chemical data, thermodynamic and kinetic data. Two independent catalytic sites exist, one for dehydration, the other for dehydrogenation, similar to those of Zinc oxide, giving rise to two parallel reaction sequencies. Criteria for developing selective catalysts towards dehydrogenation products are briefly discussed.