Dottorato in ENERGIA E AMBIENTE

Titolo della tesi: Thermo-Catalytic Reforming of waste biomass for alternative fuels production in a framework of decarbonisation

In Europe, the production of alternative biofuels represents a very relevant economic and innovative target, as several European directives and regulations are enacted to secure support for the sustainable development throughout the transport sector. To satisfy the continuity of biofuels production avoiding the risks of technological failures or feedstocks shortage, the use of wastes and second-generation biomass represents a promising solution in terms of availability, economic convenience and environmental impact on overall emissions. In fact, they can be produced worldwide without competing with other industrial uses (e.g. food industry, livestock bedding, horticulture etc.) or having possible negative impacts on environment and biodiversity. The real diversifier for the competitiveness as well as the feasibility of biofuels production is the technology. Among several thermochemical conversion systems, the Thermo-Catalytic Reforming (TCR) represents a flexible and reliable technology, capable to convert a wide range of advanced feedstocks in value-added products and fuels (i.e. char, oil and syngas). In this research, waste carbon fibres (CF) and solid grade laminate (SGL) have been investigated in a 2 kg/h lab-scale TCR reactor at the University of Birmingham. They are widely used in many applications and industrial sectors, thus contributing to high volumes of waste at end of life. Globally, it is about 130 million of tons of kraft paper produced annually and partly destined to SGL production and the global demand of carbon fibres in 2022 is equal to 127,000 tons. To evaluate the suitability of TCR technology for SGL and CF, the characterisation of both feedstocks was accomplished, and it was concluded SGL and CF can be processed via TCR. The main energy carriers (char, oil and syngas) were generated under pyrolysis temperatures of 500°C for SGL and 600°C for CF and reforming temperature of 650 °C for SGL and 680°C for CF, respectively. The different temperatures were set according to the preliminary investigation carried out on TGA for both feedstocks. The SGL oil showed good properties and its HHV reached a value of 32.72 MJ/kg. However, a successive upgrading was required to meet specifications for its use as drop in fuels. On the contrary, the CF oil production was negligible, even if its calorific value was 30 MJ/kg. The syngas produced from the treatment of SGL and CF was rich in hydrogen (about 20-40 vol%). Lastly, char revealed a calorific value of 25.94 MJ/kg and 20 MJ/kg for SGL and CF, respectively, thus exhibiting potential as a fuel as well as a catalyst in the gasification process. Overall, TCR of SGL and CF represents a novelty and it can be a promising route for the valorisation of this type of wastes. Finally, a techno-economic analysis for a commercial TCR3000 plant suggests that the technology is affordable and suitable to be commercialised. Key words: Thermo-Catalytic Reforming, Pyrolysis, Hydrotreatment, Bio-oil, Char, Syngas, Hydrogen, Advanced Feedstocks, Carbon Fibres, Laminate.