生物质精炼过程糖类分析方法研究进展

林基生物质精炼将更多的木材组分加以利用,转化为更多的化学制品和能量载体,实现林基生物质资源高效的工业化利用。其中关键技术在于传统造纸行业未充分利用的半纤维素。近年来国内外的科研机构和学者着力于半纤维素水解糖液的分析研究,其中基于现代仪器的分析方法为理论研究提供了更好的分析手段。本文作者根据文献调研总结了可服务于该新兴领域的分析方法,以期为研究者提供综合参考。     

Stabilization of Polysaccharides During Alkaline Pre-Treatment of Wood Combined with Enzyme-Supported Extractions in a Biorefinery

Specific enzymes have demonstrated an ability to increase the possibilities for extracting wood polymers. Enzymatic treatment requires an open wood structure, which was achieved by extended impregnation of the wood. However, lignin and some of the hemicelluloses, primarily glucomannan, were lost during the impregnation. To improve the carbohydrate yield, three glucomannan modification agents—sodium borohydride, polysulphide, and anthraquinone—were used, which increased the yields of the impregnated materials from 76.6% to 89.6%, 80.0%, and 81.3%, respectively. Through the use of additives, most of the glucomannan could be retained in the wood while still allowing the enzymes to penetrate the wood and attack the polymers. The additives also increased the extraction yield from 9 to 12% w/w wood. Gamanase treatment prior to the extraction increased the extraction yield to 14%. Of the three stabilizing agents, sodium borohydride was the most efficient, providing the highest extraction yields.     

A hybrid optimisation model for the synthesis of sustainable gasification-based integrated biorefinery

Depletion of fossil fuels and increasing public awareness of environmental issues has stimulated the search for alternative energy sources. Biofuels are recognised as one of the most promising alternatives to fossil fuels, as they can be produced from various types of feedstock. The efficiency and sustainability of biomass-based production can be maximised by producing biofuels along with other valuable coproducts in a “biorefinery”. This concept was proposed to make the production of biofuels and biochemicals more economically viable by taking advantage of opportunities for process integration and waste recovery. In this work, a novel hybrid optimisation model that combines superstructure-based optimisation approach and insight-based automated targeting for the synthesis of a sustainable integrated biorefinery is presented. In addition, fuzzy optimisation is also adapted to synthesize such integrated facility with the simultaneous consideration of both economic and environmental performance. Note that the proposed approach is a generic synthesis strategy that can be applied even without detailed modelling of individual processes.     

微生物转化粗甘油制备高附加值产品的研究进展

随着生物柴油产业的发展,其主要副产物粗甘油的产量也逐年增加.大量粗甘油的产生不仅给环境造成了污染,也使精制甘油的市场价格大幅度下降.甘油是一种稳定的多功能化合物,可用作精细化工合成的基本原料.利用微生物转化甘油生产各种生物基化学品,因其具有绿色环保、可持续发展等特点,越来越受到人们的重视.本文简单介绍了甘油经微生物发酵...     

Food wastes and sewage sludge as feedstock for an urban biorefinery producing biofuels and added-value bioproducts

The updated Bioeconomy Strategy document “A sustainable bioeconomy for Europe: strengthening the connection between economy, society and the environment”, which was issued by the European Commission in October 2018, encourages the exploitation of organic wastes according to a pyramidal hierarchy in which the extraction of valuable biomolecules, which will be used as they are or as precursors of high-added-value compounds, is a priority in biofuel production. This review considers a biorefinery platform in which food waste and sewage sludge are adopted to produce volatile fatty acids (VFAs) through a dark fermentation process. VFA fermentation is optimized by slightly acid pH (6–7), short hydraulic retention time (1–7 days) and high organic load rate (more than 10 gTS L⁻¹ d⁻¹). Attention has been focused on VFA exploitation for polyhydroxyalkanoate (PHA) production via a ‘feast and famine’ strategy performed in sequencing batch reactors. The obtained PHA yields are around 0.4–0.5 gPHA gCOD⁻¹. Moreover, VFAs allow for the production of biofuels, such as hydrogen and methane, through single- or double-staged anaerobic digestion. Innovative bioelectrochemical upgrade strategies for biogas helps producers to obtain biomethane for the automotive sector. Moreover, biogas has recently been tested for the production of polyhydroxybutyrate, a biodegradable and biocompatible thermoplastic made by microorganisms from C1 carbon sources (CO₂ and CH₄). Digestates from anaerobic bioreactors are still rich in nitrogen and phosphorus compounds. These latter compounds have been identified as critical raw materials due to their low availability in the European Union and to increasing demand from the growing global population. Thus, nutrient recovery from digestate allows users to close the loop of the ‘circular economy’ approach. © 2019 Society of Chemical Industry     

Placing microalgae on the biofuels priority list: a review of the technological challenges

Microalgae provide various potential advantages for biofuel production when compared with ‘traditional’ crops. Specifically, large-scale microalgal culture need not compete for arable land, while in theory their productivity is greater. In consequence, there has been resurgence in interest and a proliferation of algae fuel projects. However, while on a theoretical basis, microalgae may produce between 10- and 100-fold more oil per acre, such capacities have not been validated on a commercial scale. We critically review current designs of algal culture facilities, including photobioreactors and open ponds, with regards to photosynthetic productivity and associated biomass and oil production and include an analysis of alternative approaches using models, balancing space needs, productivity and biomass concentrations, together with nutrient requirements. In the light of the current interest in synthetic genomics and genetic modifications, we also evaluate the options for potential metabolic engineering of the lipid biosynthesis pathways of microalgae. We conclude that although significant literature exists on microalgal growth and biochemistry, significantly more work needs to be undertaken to understand and potentially manipulate algal lipid metabolism. Furthermore, with regards to chemical upgrading of algal lipids and biomass, we describe alternative fuel synthesis routes, and discuss and evaluate the application of catalysts traditionally used for plant oils. Simulations that incorporate financial elements, along with fluid dynamics and algae growth models, are likely to be increasingly useful for predicting reactor design efficiency and life cycle analysis to determine the viability of the various options for large-scale culture. The greatest potential for cost reduction and increased yields most probably lies within closed or hybrid closed–open production systems.     

Comparative Study of Isolated Polysaccharides from Triploid Poplar Using Different Solvents and Chemicals

The conversion of lignocellulose to value-added products is normally focused on fuel production; however, large-scale biorefineries require a cost-effective pretreatment process that can effectively fractionate the three main constituents of lignocellulose for the production of chemicals, fuels, and materials. In this study, a hemicellulosic biopolymer from poplar was fractionated by a mild organosolv process and the effects of various chemicals (sodium hydroxide, triethylamine, and formic acid) and alcohols on the fractionation efficiency and structural variation of hemicellulose were examined. Comparative studies indicated that an acidic catalyst decreased the purity of hemicelluloses by partial degradation of cellulose, and the core of the hemicellulosic biomacromolecule could be released and dissolved under alkaline conditions with 5.8%~19.0% yields. In addition, the use of alcohol with longer alkyl chains facilitated the release of the hemicellulosic biomacromolecule by partially cleaving the ether bonds in the lignin-carbohydrate complex (LCC); this is probably due to steric hindrance. The thermal degradation behavior showed that complete pyrolysis was easily achieved for the hemicellulosic polymer with minimal branches irrespective of its molecular weight.