Efforts to mitigate climate change primarily focus on reducing globalgreenhouse gas emissions, particularly carbon dioxide (CO₂). Without intervention,global warming could lead to a 3.2 ^◦C temperature increase, resultingin an 18 % global GDP loss. Achieving the Paris Agreement’s goal oflimiting temperature rise to 1.5 ^◦C (which if surpassed could lead to extreme climate change) requires significant cuts in GHG emissions, as outlined by theIPCC’s recommendation to decrease CO₂ emissions by 45 % from 2010 levels by 2030, reaching net-zero by 2050. Biomass, with its potential for carbon neutrality or negativity, is a vital renewable feedstock, convertible into greenfuels via thermochemical processes like gasification, pyrolysis, and anaerobic digestion. However, these processes face challenges, such as catalyst deactivationand high energy demands. Additive manufacturing and electrification are emerging solutions, offering enhanced catalyst stability and increased energy efficiency by reducing reliance on fuel combustion. This doctoral thesis focuses on an extensive overview of the state-of-theart of renewable feedstocks with a focus on its challenges and perspective, as well as investigative work based on these findings. The latter opened the pathfor the design, fabrication, electrification and testing of such 3D-printed catalysisin the catalytic reforming of renewable feedstocks. The experimental workwas aided by CFD simulations, and proofs-of-concept were developed using process simulation software and techno-economic analysis. The experimental results show a successful demonstration of the electrified catalytic reforming technology of biomass pyrolysis volatiles for syngas production, resulting incomplete bio-oil reforming to syngas, with a highest yield of 0.071 g H₂ g⁻¹ biomass with excellent catalyst stability and energy efficiency of 66 %. The CFD results show how the lattice structure of the 3D-printed catalyst resultsin a higher surface area and improved transport phenomena, which resultin enhanced mass and heat transfer properties. Furthermore, this novel 3D printed catalyst was tested for catalytic dry reforming of synthetic biogas using induction as heat source, resulting in complete reforming to syngas with minimal coke deposition, compared to commercially available catalysts, highlighting the effect of the catalyst’s geometry on its stability. Based on the electrified catalytic reforming technology, process designand development at an industrial scale were investigated to achieve integration with product upgrading (such as synthetic natural gas, i.e. SNG, and H₂ production). The developed processes were compared with non-electrified reforming technologies using mass and energy balances, as well as using techno-economic analyses, sensitivity analyses, and CO₂-equivalent analyses. Regarding SNG production, the results show a production cost of 18 SEK kg⁻¹ SNG, toward a selling price of 27 SEK kg⁻¹ SNG, resulting in an economic profit: capital investment recovery (break-even point) within two years of operation and a net cash flow of 5,000 MSEK after 20 years. In terms of process parameters the results show susceptibility to high steam-to-biomassratios and the market price of both biomass and biochar. Regarding H₂ production,electrified catalytic reforming technology results in 93 % reduction of the CO₂-equivalents compared to industrial natural gas reforming.

Insatser för att mildra klimatförändringarna fokuserar främst på att minska de globala utsläppen av växthusgaser, särskilt koldioxid (CO2). Utan ingripandeåtgärder kan den globala uppvärmningen leda till en temperaturökning på 3,2 ◦C, vilket kan resultera i en global BNP-förlust på 18 %. För att uppnåParisavtalets mål att begränsa temperaturökningen till 1,5 ◦C krävs betydande minskningar av utsläppen av växthusgaser, vilket beskrivs i IPCC:s rekommendation att minska CO2-utsläppen med 45 % från 2010 års nivåer till 2030 års nivåer senast i 2050. Biomassa, med sin potential för kol- neutralitet eller negativitet,är ett viktigt förnybart råmaterial som kan omvandlas till gröna bränslen via termokemiska processer som förgasning, pyrolys och anaerob rötning. Dessa processer står dock inför utmaningar, såsom katalysatordeaktivering och höga energibehov. Friformsframställning och elektrifieringär nya lösningar som erbjuder förbättrad katalysatorstabilitet ochökad energieffektivitet genom att minska beroendet av fossil bränsleförbränning.

Denna doktorsavhandling fokuserar på en omfattande litteraturstudie av det senaste inom förnybar energi med fokus på dess utmaningar och perspektiv, samt utredningsarbete baserat på denna studie. Det senare möjliggjorde design, tillverkning, elektrifiering och testning av en innovativ 3D-printad katalysator i den katalytiska reformeringen av förnybara energikällor. Som komplement till det experimentella arbetet användes CFD-simuleringar, och koncepttest utvecklades med hjälp av processimuleringsmjukvara och tekniskekonomisk analys. De experimentella resultaten visade en framgångsrik demonstration av den elektrifierade katalytiska reformeringen av biomassapyrolysånga för syngasproduktion. Dessa resulterade i fullständig biooljereformering, med ett högsta utbyte på 0,071 g H2 g−1 biomassa med utmärkt katalysatorstabilitet och energieffektivitet på 66 %. CFD-resultaten visade hur gitterstrukturen hos den 3D-printade katalysatorn resulterar i en högre ytarea och förbättrade transportprocesser, vilket resulterar i förbättrade massaoch värmeöverföringsegenskaper. Dessutom testades denna 3D-printade katalysator för katalytisk torreformering av syntetisk biogas med induktion som värmekälla. Det resulterade i fullständig reformering till syngas med minimal koksavsättning, jämfört med kommersiellt tillgängliga katalysatorer, vilket framhäver vilken effekt katalysatorns geometri har på dess stabilitet.

Baserat på den elektrifierade katalytiska reformeringstekniken undersöktes process- och designutveckling i industriell skala för att kunna integrera med produktuppgradering, såsom produktion av syntetisk naturgas (SNG) och vätgas. De utvecklade processerna jämfördes med icke-elektrifierade reformeringstekniker med hjälp av massa- och energibalanser, samt teknoekonomiska analyser, känslighetsanalyser och CO2-ekvivalenter. Gällande SNGproduktion visade resultaten en produktionskostnad på 18 SEK kg−1 SNG, mot ett försäljningspris på 27 SEK kg−1 SNG, vilket resulterar i en ekonomisk vinst:återinvestering inom tvåårs drift och ett nettokassaflöde på 5.000 MSEK efter 20år. Resultaten visade också kännslighet för höga ånga- till-biomassa-förhållanden och marknadspriset för både biomassa och biokol. Dessutom visade resultaten att vätgasproduktionen genom elektrifierad katalytisk reformeringsteknik resulterar i 93 % minskning av CO2-ekvivalenter jämfört med industriell naturgasreformering.

Biomass is a key renewable feedstock for producing green fuels; however, renewable feedstock presents a high risk for catalyst deactivation and poor stability. In addition, the heat source of industrial reforming processes comes from fuel combustion and most heat is lost in the flue gas. In this study, a Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and 3D-printed. A reforming process was then conducted by directly heating the catalyst using electricity instead of fuel combustion. This e-reformer technology was demonstrated in continuous catalytic steam reforming of biomass pyrolysis volatiles. A high H2 yield of ≈7.1 wt % of biomass has been obtained at a steam-to-biomass (S/B) ratio of 4.5, reforming temperature of 800 °C and weight hourly space velocity (WHSV) of 310 h−1, resulting in an energy consumption of 8 kWhel kg−1 biomass (66% energy efficiency). The results show a successful demonstration of the electrified technology with improvement potential; in addition, a process was designed and assessed economically for synthetic natural gas (SNG) production of 80 MWHHV, comparing electrification and partial oxidation in different scenarios.

Pyrolysis of biomass plus catalytic reforming of its pyrolysis volatiles is a green alternative to produce solid (biochar) and gaseous (syngas) fuels that have several valuable applications; however, this catalytic process suffers from fast deactivation, and its energy consumption is yet to be studied, factors that determine the process's feasibility in industrialisation. To address these issues, the direct electrification of a 3D-printed FeCrAl heater coated with 15.5 % Ni/Al2O3 was tested in a parametric study in the catalytic steam reforming of biomass pyrolysis volatiles, in order to investigate the effect of the S/B ratio and space–time on the syngas yield and composition. Complete bio-oil reforming was obtained at a biomass feed rate of ≤ 1 g min−1 and a S/B ratio of ≥ 2, and stability close to 100 % was estimated after over four hours of operation. Nonetheless, the produced syngas is rich in C1 – C3 gases and moderately low in H2 (≈ 2 wt %). The effect of the catalyst's structure on the bio-oil reforming and heat efficiency was complemented using CFD simulations and compared to a simple geometry based on commercial extruded monoliths. Finally, the biomass-derived syngas upgrading to H2 production was assessed using different process simulations and compared to existing H2-producing technologies in terms of energy efficiency and emissions.

This study introduces a distributed electrified heating approach that is able to innovate chemical engineering involving endothermic reactions. It enables rapid and uniform heating of gaseous reactants, facilitating efficient conversion and high product selectivity at specific equilibrium. Demonstrated in catalyst-free CH4 pyrolysis, this approach achieves stable production of H2 (530 g h−1 L reactor−1) and carbon nanotube/fibers through 100% conversion of high-throughput CH4 at 1150 °C, surpassing the results obtained from many complex metal catalysts and high-temperature technologies. Additionally, in catalytic CH4 dry reforming, the distributed electrified heating using metallic monolith with unmodified Ni/MgO catalyst washcoat showcased excellent CH4 and CO2 conversion rates, and syngas production capacity. This innovative heating approach eliminates the need for elongated reactor tubes and external furnaces, promising an energy-concentrated and ultra-compact reactor design significantly smaller than traditional industrial systems, marking a significant advance towards more sustainable and efficient chemical engineering society.

Catalyst research on reforming processes for syngas production has mainly focused on the active metals and support materials, while the effect of the catalyst's geometry on the reforming reactions has been poorly studied. The application of 3D-printed materials with enhanced geometries has recently started to be studied in heterogeneous catalysis and is of interest to be implemented for reforming biomass and plastic waste to produce H2-rich syngas. In this study, a geometry-enhanced 3D-printed Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and fabricated. The catalyst was used for batch steam reforming biomass pyrolysis volatiles for syngas production at different parameters (temperature and steam-to-carbon ratio). The results showed complete reforming of pyrolysis volatiles in all experimental cases, a high H2 yield of ≈ 7.6 wt% of biomass was obtained at the optimized steam-to-carbon ratio of 8 and a reforming temperature of 800 °C, which is a higher yield compared to other batch reforming tests reported in the literature. Moreover, CFD simulation results in COMSOL Multiphysics demonstrated that the POCS configuration improves the reforming of pyrolysis volatiles for tar/bio-oil reforming and H2 production thanks to enhanced mass and heat transfer properties compared to the regular monolithic single-channel configuration.

Dedicated bioenergy combined with carbon capture and storage are important elements for the mitigation scenarios to limit the global temperature rise within 1.5 °C. Thus, the productions of carbon-negative fuels and chemicals from biomass is a key for accelerating global decarbonisation. The conversion of biomass into syngas has a crucial role in the biomass-based decarbonisation routes. Syngas is an intermediate product for a variety of chemical syntheses to produce hydrogen, methanol, dimethyl ether, jet fuels, alkenes, etc. The use of biomass-derived syngas has also been seen as promising for the productions of carbon-negative metal products. This paper reviews several possible technologies for the production of syngas from biomass, especially related to the technological options and challenges of reforming processes. The scope of the review includes partial oxidation (POX), autothermal reforming (ATR), catalytic partial oxidation (CPO), catalytic steam reforming (CSR) and membrane reforming (MR). Special attention is given to the progress of CSR for biomass-derived vapours as it has gained significant interest in recent years. Heat demand and efficiency together with properties of the reformer catalyst were reviewed more deeply, in order to understand and propose solutions to the problems that arise by the reforming of biomass-derived vapours and that need to be addressed in order to implement the technology on a big scale. 

A syngas production based on a biomass pyrolysis followed by an in-line catalytic reforming process is a promising method to help curb greenhouse gas emissions. The use of biochar as the reforming catalyst is economically and technologically attractive. A continuous pyrolysis combined with an in-line biochar-catalytic reforming of the pyrolysis vapor was investigated in a comprehensive system consisting of an auger reactor and a downstream fixed-bed rector. The effect of the weight hourly space velocity (WHSV), particle size and morphology of biochar, and the pressure drop of the biochar bed on the catalytic performance were discussed. The results indicated that a higher syngas yield with a higher H2+CO proportion was obtained when using a lower WHSV, due to a longer residence time. The highest syngas and H2 yields were obtained when using biochar with the smallest particles sizes (0.6-1 mm), i.e. the highest bed pressure drops. The use of biochar particles, which are more spherical and rounded, resulted in higher syngas yields, H2 +CO proportions, and H2 yields due to the enhanced heat and mass transfer favored by the rounded shape. Up to 12 mmol H2/g-biomass was obtained, corresponding to a dry gas yield of 0.68 Nm3/kg , containing 39 vol. % H2 and 27 vol. % CO.  The use of biochar as a reforming catalyst showed a relatively stable catalytic performance after during a 100-minutes of running the experimentexperimental run-time.