Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

A review on pyrolysis of plastic wastes

Hydrogen production, storage, transportation and key challenges with applications: A review

A review on thermal and catalytic pyrolysis of plastic solid waste (PSW)

A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dye--Acid Blue 113.

The continuous increase in the generation of waste plastics together with the need for developing more sustainable waste management policies have promoted a great research effort dealing with their valorization routes. In this review, the main thermochemical routes are analyzed for the valorization of waste polyolefins to produce chemicals and fuels. Amongst the different strategies, pyrolysis has received greater attention, but most studies are of preliminary character. Likewise, the studies pursuing the incorporation of waste plastics into refinery units (mainly fluid catalytic cracking and hydrocracking) have been carried out in batch laboratory-scale units. Other promising alternative to which great attention is being paid is the process based on two steps: pyrolysis and in-line intensification for olefin production by means of catalytic cracking or thermal cracking at high temperatures.

Thermochemical routes for the valorization of waste polyolefinic plastics to produce fuels and chemicals. A review

The current review provides an assessment of the main waste plastics valorization routes to produce syngas and H2, thus covering different gasification strategies and other novel alternative processes, such as pyrolysis and in-line catalytic steam reforming The studies dealing with plastics gasification are in general scarce However, due to the knowledge acquired on biomass and coal gasification, the state of development of plastic gasification technologies is considerable and, in fact, several gasification studies have been performed at pilot scale units Air gasification is the most studied and developed strategy and pursues the production of a syngas for energy purposes In spite of the higher H2 content and heating value of the gas produced by steam gasification, this alternative faces significant challenges, such as the energy requirements of the process and the tar content in the syngas Moreover, the co-gasification of plastics with coal and biomass appears to be a promising valorization route due to the positive impact on process performance and greater process flexibility Other promising alternative is the pyrolysis and in-line reforming, which allows producing a syngas with high hydrogen content and totally free of tar

Recent advances in the gasification of waste plastics. A critical overview

Evaluation of thermochemical routes for hydrogen production from biomass: A review

Pinewood sawdust flash pyrolysis has been performed in continuous mode in a pilot plant provided with a conical spouted bed reactor, in the 400–600 °C range. The influence of temperature on the pyrolysis yields and product properties has been studied. Product analysis has been carried out on-line by means of chromatographic methods. High liquid yields have been achieved, with the maximum bio-oil yield (75 wt%) at 500 °C. Gas yield is very low at low temperatures and this fraction is mainly composed of carbon dioxide, carbon monoxide and small amounts of methane, hydrogen and C2–C4 hydrocarbons. Bio-oil has been characterized and its major compounds are phenols, specifically guaiacols at low temperatures and catechols at high temperatures. At 600 °C, there is an increase in light compounds due to the cracking reactions, but no aromatic compounds have been detected due to the low residence time of the volatiles in the reactor. The fuel properties of the bio-oil have been measured and the results indicate that it can be a potential substitute to conventional fuels, although its heating value should be improved by subjecting to further treatments. Char can be used as energy source or as active carbon. The char obtained at 600 °C has a high surface area and is suitable for active carbon production.

Maider Amutio

Papers

Thermochemical routes for the valorization of waste polyolefinic plastics to produce fuels and chemicals. A review

Recent advances in the gasification of waste plastics. A critical overview

Evaluation of thermochemical routes for hydrogen production from biomass: A review

Influence of temperature on biomass pyrolysis in a conical spouted bed reactor

Bio-oil production from rice husk fast pyrolysis in a conical spouted bed reactor