Slow pyrolysis of lignin rich residue from lignocellulosic biorefining operations

Europe is committed to have a bio-based economy in 2030. It follows that a huge contribution of biorefinery products on the European demand for chemicals, energy, materials and fibers is expected in the near future. To be environmentally and economically sustainable, biorefinery will need to be flexible, versatile, energy and cost efficient [1]. In a lignocellulose based biorefinery, the sugar platform that leads to bioethanol and added-value products through biochemical processes represents a challenging option. After ethanol distillation a lignin reach residue (LRR) is produced and used as energy source. However, it is currently underutilized with about 60% more lignin generated than is needed to meet the internal energy use [2, 3]. The exploitation of this residue for the combined production of biofuels and added value chemicals and materials represents a key factor for the increase of the efficiency of the overall ethanol production chain and its valorization is mandatory for the viability of future biorefinery operations. Please click Additional Files below to see the full abstract

Pyrolysis atmosphere effect on biochar properties and PTEs behaviour

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Fate of lead and other heavy metals during pyrolysis of lignocellulosic biomass

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Perspectives in the use of biochars as low-cost CO2 adsorbents

The recognized versatility of biochar in environmental remediation issues opened up an increasing interest in its applications in multidisciplinary areas of science and engineering. Possible biochar applications include carbon sequestration, soil fertility improvement, pollution remediation and agricultural by-product/waste recycling. A proper application in specific environmental areas requires a fulfilled biochar chemico-physical characterization and overall properties. Please click on the file below for full content of the abstract

Effect of pyrolysis conditions on sewage sludge derived biochars for high value composites applications

The economy of the whole wastewater treatment system is significantly burdened by the increasing amounts of sewage sludge due to the progressive implementation of the Urban Waste Water Treatment Directive 91/271/EEC and by the complexity of the treatments required for guaranteeing a safe handling and a proper end-of-life of the sludge. For this reason, thermal treatments of sewage sludge have been studied in the past for their efficient valorization in terms of energy and/or matter recovery. Among them, pyrolysis represents a viable route aiming at the recycling of resources without production of harmful substances to the humans or the environment. A lot of work has been done on the use of sludge-derived char as a fertilizer and soil conditioner showing its safer application with respect to the untreated sludge. The nutrients were intensified with the temperature rising (except nitrogen) and the bioavailability and the leaching of heavy metals was reduced [1]. However, the physical and chemical characteristics of biochar can be exploited also for the production of high value-added materials. Carbon materials such as nanotubes received a great attention due to their ability to enhance mechanical, electrical and thermal properties of polymer composites [2], but high costs and low reproducibility have discouraged their use. In this study sludge-derived char (SCHAR) is studied as a possible alternative to other high cost carbon fillers. Sewage sludge from a civil wastewater treatment plant was pyrolyzed both in slow [3] and fast [4] pyrolysis conditions at three different temperatures, 500, 600 and 700 °C. A lignocellulosic biomass was also processed in the same experimental conditions for comparing the SCHARs with typical biochars (BCHARs). Please click Additional Files below to see the full abstract

Biochar addition in the anaerobic digestion of the organic fraction of municipal solid waste for biogas production

The continuous decline of fossil fuel availability and the ever increasing concern about environmental pollution, expressed by scientists, governments and public at large, are stimulating the research on renewable energy production. In this perspective, anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is recently meeting with increasing interest. It is a process viable both from an economic and technological standpoints, capable to combine the environmental friendly re-cycle of large amount of OFMSW combined to the production of methane, an excellent fossil-based fuels substitute (Chatterjee and Mazumder, 2016). Please click on the file below for full content of the abstract

Green functionalization of biochar via mechanochemical approach

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Membrane and Electrochemical Based Technologies for the Decontamination of Exploitable Streams Produced by Thermochemical Processing of Contaminated Biomass

Phytoremediation is an emerging concept for contaminated soil restoration via the use of resilient plants that can absorb soil contaminants. The harvested contaminated biomass can be thermochemically converted to energy carriers/chemicals, linking soil decontamination with biomass-to-energy and aligning with circular economy principles. Two thermochemical conversion steps of contaminated biomass, both used for contaminated biomass treatment/exploitation, are considered: Supercritical Water Gasification and Fast Pyrolysis. For the former, the vast majority of contaminants are transferred into liquid and gaseous effluents, and thus the application of purification steps is necessary prior to further processing. In Fast Pyrolysis, contaminants are mainly retained in the solid phase, but a part appears in the liquid phase due to fine solids entrainment. Contaminants include heavy metals, particulate matter, and hydrogen sulfide. The purified streams allow the in-process re-use of water for the Super Critical Water Gasification, the sulfur-free catalytic conversion of the fuel-rich gaseous stream of the same process into liquid fuels and recovery of an exploitable bio-oil rich stream from the Fast Pyrolysis. Considering the fundamental importance of purification/decontamination to exploit the aforementioned streams in an integrated context, a review of available such technologies is conducted, and options are shortlisted. Technologies of choice include polymeric-based membrane gas absorption for desulfurization, electrooxidation/electrocoagulation for the liquid product of Supercritical Water Gasification and microfiltration via ceramic membranes for fine solids removal from the Fast Pyrolysis bio-oil. Challenges, risks, and suitable strategies to implement these options in the context of biomass-to-energy conversion are discussed and recommendations are made

Composizione chimica e caratteristiche di combustione dei liquidi derivati da pirolisi di biomasse

[ITALIANO] Gli oli di pirolisi (bio-oli) sono utilizzati in applicazioni statiche per la generazione di energia elettrica. Studi precedenti hanno contribuito ad una caratterizzazione chimica dei bio-oli estesa, ma parziale. Gli studi di combustione, invece, hanno analizzato il comportamento insolito di tali oli solo da un punto di vista fenomenologico. Lo scopo di questa tesi è quello di fornire una caratterizzazione il più possibile dettagliata dei bio-oli utilizzando di diverse tecniche analitiche (GC/MS e HPLC) e di mostrare l’influenza di alcuni parametri operativi (natura della biomassa), sulla loro composizione chimica. Infine si propone un primo tentativo di correlazione fra composizione dei bio-oli e comportamento in combustione. Natura e composizione chimica della biomassa determinano la composizione dei bio-oli. Gli hardwoods producono prevalentemente acidi carbossilici, mentre gli zuccheri sono le specie più abbondanti nei liquidi derivati da softwoods. Gli hardwoods producono sia guaiacoli che siringoli, mentre i softwoods forniscono unicamente guaiacoli. Gli studi di combustione sono effettuati in condizioni di controllo cinetico e in condizioni di controllo dei fenomeni di trasporto. Dai primi emerge che gli zuccheri derivanti dall’olocellulosa, non solo la lignina pirolitica, contribuiscono alla formazione di char secondario. Nella combustione di singola goccia si susseguono 4 fasi: riscaldamento, devolatilizzazione microesplosiva, combustione omogenea, combustione eterogenea. I tempi e le temperature di riscaldamento variano linearmente col del diametro iniziale della goccia. La nucleazione delle sacche di vapore è fortemente dipendente dal contenuto d’acqua. Il contenuto di volatili ha una duplice influenza sui tempi di ignizione: il loro maggiore contenuto allunga i tempi di evaporazione e al tempo stesso riduce la viscosità del liquido favorendo le microesplosioni e riducendo i tempi di evaporazione della goccia madre. La resa di residuo solido dipende dall’entità delle microesplosioni, mentre le differenti condizioni di riscaldamento non influenzano il rapporto fra volume della cenosfera e volume iniziale della goccia. / [ENGLISH]Liquids derived by biomass pyrolysis (bio-oils) are used for industrial applications for energy and power generation. Previous works gave an important but incomplete contribution to their chemical characterization. Furthermore their combustion behaviour has been analyzed only with regard to fenomenological aspects. This work is devoted to supply an extensive chemical characterization of bio-oil applying different analytical techniques (GC/MS e HPLC) and to highlight the influence of some operative variables (e.g. initial biomass) on their chemical composition. A first attempt to correlate chemical composition and combustion behaviour is also carried out. The results obtained show that biomass nature affects strongly the chemical composition of bio-oils. Hardwoods cellulose produces mostly carboxylic acids whilst lignin gives guaiacols and syringols. On the contrary carbohydrates are the main compounds derived by the pyrolysis of softwoods cellulose; softwoods lignin produces only negligible amounts of syringols. Combustion experiments are carried out in conditions of both kinetic (thermogravimetric analysys) and transfer phenomena control (single drop combustion). Thermogravimetric analyses show that carbohydrates derived from olocellulose pyrolysis and not only pyrolytic lignin lead to the formation of secondary char. In the single drop combustion four steps are observed: drop heating, microexplosive devolatilization, gas phase homogeneous combustion, heterogeneous combustion. Heating times and temperatures depend linearly on the initial drop diameter. The nucleation of vapour bubbles is strongly influenced by water content. The presence of volatile species has two opposite effects on the drop vaporization time: a high volatiles content is responsible of longer vaporization times, but at the same time it lowers liquid viscosity enhancing the microexplosive events. The mass yield of solid residue depends on the miceoexplosive events whilst the heating conditions do not affect its volumetric yield

Cellulose slow pyrolysis products in a pressurized steam flow reactor

ABSTRACT A key strategy to achieve an acceptable degree of matter and energy recovery from vegetal waste disposal is the use of a steam-assisted pyrolysis process that operates at low heating rates and elevated pressure. This procedure, which is different from incineration and fast pyrolysis processes, is expected to reduce the production of secondary hazardous products and produce a residual char with chemical–physical properties comparable to those typical of activated carbon. However, gaseous and condensable products of the process must be demonstrated to allow for a recovery of energy to an extent that can make the process self-sustainable. To clarify these aspects and define the optimal operating conditions of the pro- cess, a multi-plate laboratory reactor was designed and constructed. This paper provides a description of the primary design criteria and operating conditions for a steam pyrolysis process. In addition, the effects of process temperature and pressure on products yields and gas and char characteristics are presented indicating the suitability of the process. In the temperature range examined, steam affects positively char and gas properties. On the other hand, pressure affects, mainly, gas yield and determines only minimal changes in char characteristics