environment each year, an emblem of our increasingly unsustainable economic system in which materials and energy are produced, used and promptly discarded. Photoreforming is a sunlight-driven technology that can help disrupt this linear model by simultaneously reclaiming the value in waste and contributing to renewable hydrogen production. This Review examines the advantages and challenges of photoreforming of real waste streams. By reviewing literature on photoreforming and conducting basic techno-economic and life cycle assessments, we identify key pathways for enhancing the impact of photoreforming for a carbon-neutral future.

Solar-driven reforming uses sunlight and a photocatalyst to generate H 2 fuel from waste at ambient temperature and pressure. However, it faces practical scaling challenges such as photocatalyst dispersion and recyclability, competing light absorption by the waste solution, slow reaction rates and low conversion yields. Here, the immobilisation of a noble-metalfree carbon nitride/nickel phosphide (CN x j Ni 2 P) photocatalyst on textured glass is shown to overcome several of these limitations. The 1 cm 2 CN x j Ni 2 P panels photoreform plastic, biomass, food and mixed waste into H 2 and organic molecules with rates comparable to those of photocatalyst slurries. Furthermore, the panels enable facile photocatalyst recycling and novel photoreactor configurations that prevent parasitic light absorption, thereby promoting H 2 production from turbid waste solutions. Scalability is further verified by preparing 25 cm 2 CN x j Ni 2 P panels for use in a custom-designed flow reactor to generate up to 21 μmol H 2 m À 2 h À 1 under "real-world" (seawater, low sunlight) conditions. The application of inexpensive and readily scalable CN x j Ni 2 P panels to photoreforming of a variety of real waste streams provides a crucial step towards the practical deployment of this technology.

The recycling rates, especially those from plastic packaging waste, have to be increased according to the European Union directive in the next years. Besides many other technologies, the pyrolysis of plastic wastes seems to be an efficient supplementary opportunity to treat mixed and unpurified plastic streams. For this reason, a pyrolysis process was developed for the chemical recycling of hydrocarbons from waste polyolefins. The obtained products can be further processed and upgraded in crude oil refineries, so that also monomers can be recovered, which are used for the plastic polymerization again. However, to achieve a scale up to a demo plant, a kinetic model for predicting the yields of the plastic pyrolysis in a tubular reactor is needed. For this reason, a pilot plant was built, in which different plastics and carrier fluids can be tested. Based on the data generated at the pilot plant, a very practical and suitable model was found to describe the plastic co-pyrolysis of the carrier fluid with polypropylene (PP) and low density and high density polyethylene (HDPE and LDPE), respectively. The physical and chemical mechanisms of the co-pyrolysis in the tubular reactor are successfully investigated.

In 2018, the EU's revised Renewable Energy Directive came into force, increasing renewable energy targets for all energy sectors while limiting the use of first‐generation biomass as feedstock. Fuel components like methanol, ethanol, propanols, and butanols represent promising candidates to enable the targets for transportation to be achieved because they can be used with existing infrastructure and can be further processed to give additives and substitutes. A wide variety of feedstocks and processes are available for this purpose. In this review, the thermocatalytic and biological synthesis routes for C1–C4 alcohol fuels are summarized to illustrate the many alternatives. They include biomass and waste gasification and carbon capture and utilization to obtain syngas for catalytic conversion, fermentation of sugars from lignocellulosic feedstock, and novel, less developed pathways like syngas fermentation, glycerol conversion, and biogas reforming. The current state of technology is presented by discussing the advantages and technical hurdles, and by introducing recent scaled‐up approaches. This demonstrates the need for further research and development. The assessment of techno‐economic analyses in the literature illustrates the dominant factors affecting production costs and reveals the broad range of feasibility of the various production routes. The review shows that the routes most similar to conventional, well‐established syntheses bear the highest potential to be implemented in the short and medium term. The availability of cheap and abundant feedstock also plays a crucial role. Methanol synthesis from biomass gasification and ethanol, and acetone‐butanol‐ethanol fermentation from lignocellulosic biomass, are therefore considered to be very promising. © 2020 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Zusammenfassung Kunststoffabfälle, speziell Verpackungsabfälle, liegen oft als Gemische mit hohem Verschmutzungsgrad vor. Die werkstoffliche Verwertung wird dadurch enorm erschwert, da die Sortierung und Reinigung dieser Fraktionen in vielen Fällen nicht ökonomisch sinnvoll oder technisch umsetzbar sind. Um diese Materialströme dennoch rohstofflich rezyklieren zu können, bietet das chemische Recycling eine vielversprechende Methode durch die Rückgewinnung von Einsatzstoffen für die Kunst-und Kraftstoffproduktion sowie für die petrochemische Industrie. Durch das Einwirken von Wärme, Katalysatoren und Lösungsmitteln werden dabei die Polymerketten in kürzere Einheiten bis hin zu Monomeren aufgespalten. Die dabei gewonnenen Kohlenwasserstoffe können dem Stoffkreislauf erneut zugeführt werden, um primäre Ressourcen zu ersetzen. Diese Technologien weisen eine hohe Toleranz gegenüber Störstoffen und Sortenunreinheiten auf und sind deshalb besonders attraktive Optionen für die Verwertung von verunreinigten Verpackungsabfällen. In den letzten 40 Jahren wurden hierzu verschiedene Ansätze zur Solvolyse und Pyrolyse mit und ohne Katalysator verfolgt, die zugrunde liegenden Mechanismen untersucht sowie zahlreiche Reaktorsysteme und Prozesswege entwickelt. Ein Überblick über die chemischen Die AutorInnen A. Lechleitner, D. Schwabl und T. Schubert trugen gleichermaßen zu dieser Arbeit bei und sind daher als Erstautoren anzusehen.