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

Abstract

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.