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Herein, a series of Ru/ZTCs samples were prepared using LaY zeolite-templated carbon as a support. Characterizations showed that the unique structure of the ZTCs and the chemical state of Ru facilitated superior HER performance compared to other carbon-supported samples. This work offers a new strategy for designing excellent electrocatalysts. [ABSTRACT FROM AUTHOR]

Hydrothermal processing (e.g., hydrothermal liquefaction) is one of the most promising systems to valorize a wide range of biomass. However, a large amount of aqueous byproduct is generated, which contains high soluble concentrations of both organics and nutrients. Thus, valorization of the aqueous byproduct can be clearly beneficial for the environment and energy recovery. Various physicochemical systems have been recognized for the valorization of aqueous byproducts, such as chemical, thermochemical, and electrochemical systems. Accordingly, this article reviews the valorization of the aqueous byproduct from hydrothermal processing (mainly hydrothermal liquefaction) from several points of view, starting with the characteristics of the aqueous byproduct originating from the hydrothermal processing of diverse biomass. The recent progress in numerous physicochemical systems, including catalytic hydrothermal gasification and microbial electrolysis cells, is comprehensively demonstrated with emphasis on their combinations since integrated systems allow energy and nutrients to be recovered more environmentally and economically feasible. The fundamentals, advantages, limitations, and the most recent findings faced in the development of each physicochemical system are also elucidated. Subsequently, the new concept of systems thinking is proposed to evaluate these systems, and a systemic framework is presented to consolidate the practical applications of these systems. Consequently, this review illustrates both the future perspectives of wastewater valorization and the milestones that should be achieved in the future. [ABSTRACT FROM AUTHOR]

The conversion of biomass primary pyrolysis vapors over several β-zeolites with silica-to-alumina ratios (SAR) varying from 21 to 250 was carried out in a flow microreactor to investigate the effect of number of acid sites on product speciation and deactivation of the catalyst. Experiments were conducted using a horizontal fixed bed semi-batch reactor in which up to 40 discrete 50 mg boats of biomass were pyrolyzed and the vapors upgraded over 0.5 g of the catalyst. Products were measured with a molecular beam mass spectrometer (MBMS). These studies were complemented using a tandem micropyrolyzer connected to a GCMS (py-GCMS) for speciation and quantifying the products. In the py-GCMS experiments, several 0.5 mg loads of pine were pyrolyzed sequentially and the vapors upgraded over 4 mg of catalyst. In all of these experiments, real-time measurements of the products formed were conducted as the catalyst aged and deactivated during upgrading. The results from these experiments showed that: (1) fresh catalyst for β-zeolites with lower SAR (more acid sites) produced primarily aromatic hydrocarbons and olefins with no detectable oxygen-containing species; (2) a suite of oxygenated products was observed from fresh catalysts with high SAR (few acid sites), indicating that 0.5 g of these catalyst materials did not have sufficient acid sites to deoxygenate vapors produced from pyrolysis of 50 mg of pine. This suite of oxygen containing products consisted of furans, phenol and cresols. The amount of coke deposited on each catalyst and the yield of aromatic hydrocarbons increased with the number of acid sites. However, while the catalysts were active, the biomass selectivity towards coke and hydrocarbons remained essentially constant on the catalysts of varying SAR. [ABSTRACT FROM AUTHOR]

This study demonstrates the use of isotopic labelling and NMR to study the HDO process. As far as we know, this is the first reported effort to trace the incorporation of hydrogen in the HDO process of lignin pyrolysis oil thereby providing key fundamental insight into its reaction mechanism. [ABSTRACT FROM AUTHOR]

The torrefaction of Loblolly pine (Pinus taeda) was examined at 250 and 300 °C, to determine the effects of treatment temperatures on the chemical structure of the torrefied Loblolly pine. Solid-state cross-polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy was used to characterize the torrefied and native Loblolly pine. The NMR results indicate that aryl-ether bonds in lignin were cleaved during the torrefaction. The methyl carbons in hemicellulose acetyl groups were no longer present after the torrefaction at 250 °C for 4 h, which is consistent with HPLC carbohydrate analysis of the torrefied wood which indicated that the hemicellulose fraction of pine was completely absent, whereas the cellulose and lignin remained largely intact. Under these conditions the torrefied wood has a relatively high energy yield of 81.29% and a HHV of 24.06 MJ kg−1. After torrefaction at 300 °C for 4 h, the cellulose and hemicellulose in the wood were completely eliminated, the residue contains enriched amounts of carbonyl groups, aromatic carbons and methoxyl groups, which represent complex condensed aromatics, these aromatics units were linked with aliphatic C–O and C–C bonds and the product has a very high HHV of 32.34 MJ kg−1. [ABSTRACT FROM AUTHOR]

A common goal in present and future forestry, biofuels and biomaterials practices, is the need to valorize lignocellulose processes to maximize value and optimize autonomic economy. Consequently, a key focus of modern biorefining is the on-site utilization of all residual materials generating products of the highest possible value. The LignoBoost process, recently demonstrated on the pilot-scale at Kraft pulp mills, injects CO2 into pulping liquors which results in a lower solution pH and thereby precipitates lignin. The present paper compares and evaluates the pyrolysis of pulping liquor lignins precipitated by sulfuric acid (pH 3) and the aforementioned CO2 method (pH 10.5 and 9.5). The CO2 based process yielded lignin that showed superior pyrolysis properties including low gas formation and increased bio-oil yields, close to 40%, consisting primarily of low (∼150 g mol−1) molecular weight compounds. Subsequent NMR analysis showed that the oils exhibit favorable changes in functionalities, e.g. loss of aromatic and gain in aliphatic carbon percentages as well as decrease in carboxyl and methoxyl (oxygen containing) groups. Moreover, NMR results further confirmed previously hypothesized lignin pyrolysis reactions, while at the same time showed the potential of CO2 precipitated lignin for pyrolysis and subsequent liquid biofuel production. [ABSTRACT FROM AUTHOR]

Correction for 'Advances in energy systems for valorization of aqueous byproducts generated from hydrothermal processing of biomass and systems thinking' by Yexuan Gu et al., Green Chem., 2019, 21, 2518–2543. [ABSTRACT FROM AUTHOR]

Bio-oil is a valuable liquid product obtained from pyrolysis of biomass and it contains tens of hundreds of compounds, which brings about difficulties for characterization with various analytical methods. 13 C NMR has advantages over other detection methods as it can characterize the entire composition of bio-oil and distinguish different types of carbon. But various shortcomings limit the application of 13 C NMR. This study was carried out to develop a quantitative 13 C NMR method to determine different functional groups in pyrolysis bio-oils with short NMR time and good accuracy, and propose a simulation of C, H, and O content for pyrolysis oils based on 13 C NMR analysis. In order to solve long-term NMR problems, relax reagent has been added and the results show that it is an effective way to shorten the NMR time. Moreover, the aging problem is not obvious in the short-term NMR test, so the effect of aging on the test results can be neglected. Three types of substances with different oxygen content have been employed to verify the feasibility of the C, H, and O calculation methods and the result errors of all elements are small, which shows it is reliable for the simulation data of C, H and O content., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)