Fluidized catalytic cracking (FCC) converts hydrocarbons in the presence of a catalyst based on faujasite zeolite (USY and REY). While hydrocarbon is poorly reactive, biomass and its derived compounds are highly functionalized and not suitable to a typical FCC process. To overcome this limitation biomass was first converted into a dense and stable bio-crude composed mainly of ketal-sugar derivatives by using acetone in diluted acid. Here, a representative compound of this bio-crude, 1,2:3,5-di-O-isopropylidene-α-D-xylofuranose (DX) in n-hexane, was converted by USY and a commercial FCC catalyst containing USY, at 500°C, in a fixed bed and fluidized bed reactors, respectively. Faujasite Y is very efficient in converting DX. More than 95% conversion was observed in all tests. Over 60 wt.% was liquid products, followed by gas products and only around 10% or less in coke. The higher the catalyst activity the greater the aromatics in the liquid products and yet higher coke yields were observed. In particular, simulating more practical application conditions: using deactivated catalyst in a fluidized bed reactor, improved green hydrocarbons production (mono-aromatic up to 10 carbons and light hydrocarbon up to eight carbons) and unprecedented lower coke yield (≈5 wt.%) for bio-feeds. The present results further suggest that catalyst will play a primary role to convert the bio-crude into target hydrocarbons and overcome the transition of a non-renewable to a renewable refinery feed.
This review focuses on tree health assessment in urban forest, specifically on the methodologies commonly used to detect levels, dimensions, and location of wood deterioration. The acknowledged benefits to the urban forestry area from the application of assessment techniques are also addressed. A summary is presented of the different methodologies, such as visual analyses, acoustic tomography, and digital wood inspection drill, with the underlined importance of the biodeterioration of wood by fungi and termites.
This paper addresses the problem of summer branch drop (SBD) in urban forests, namely through detecting the causes of this unpredictable event, aiming at preventing and increasing the control of this phenomenon, while using the most recent methodologies to detect wood deterioration, namely visual tree assessment (VTA), drilling resistance, and acoustic tomography, in an isolated and associated way. The study considers events in the cities of Arcos de Valdevez in Viana do Castelo district (Site 1), Ponte de Lima in Viana do Castelo district (Site 2), Montemor-o-Novo in Évora district (Site 3), and Paços de Ferreira in Porto district (Site 4), targeting trees of public interest. Given the phytosanitary condition recognized using nondestructive equipment, a set of measures for the preservation of the tree elements and their history are suggested. SBD is mostly related to internal degradation. A VTA diagnosis, applied in isolation, could lead to an incorrect prognosis of the internal degradation. So, it is important to confirm of the presence of biotic agents through equipment (acoustic tomography and drilling resistance). Even with instrumental diagnostics, for reducing the subjectivity of the approach to estimating the SBD, a global analysis is necessary, including dendrometric parameters, predisposing or inciting factors, lower tree defences against internal degradation due to environmental conditions, and biotic agents.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.