Conversion of yeast by hydrothermal treatment under reducing conditions

In the work reported here, baker’s yeast (Saccharomyces cerevisiae) was used as feed for the production of liquid biofuels in a continuous one-step process under hydrothermal conditions in the presence of excess hydrogen and K₂CO₃. The yeast conversion experiments were performed in an up-flow reactor under near-critical water conditions (T 330–450 °C, p 20–32 MPa). The products consisted of three phases, an oil-like organic phase, a gaseous phase, and an aqueous phase. Higher concentrations of organic carbon in the process resulted in a higher product yield. The heating value of the organic phase was up to 38.6 MJ/kg. Liquefaction of yeast without any addition of K₂CO₃ also resulted in liquid oil, but the quality and the yield of the oil product were lower. A reaction temperature of 400 °C was found to be optimal for the oil yield and quality.     

金属基离子液体催化生物质转化研究进展

生物质是自然界中含量丰富且唯一可再生的有机碳资源,可以经过化学反应转化为高附加值碳基化学品和燃料,被认为是传统化石资源的理想替代品。催化材料的设计开发是生物质资源开发和利用的关键所在,离子液体因其独特的可设计性,在生物质资源利用过程中得到广泛应用。鉴于金属活性中心的催化活性以及离子液体的可设计性,将金属活性中心引入离子液体中制备金属基离子液体催化剂在生物质领域受到广泛关注,并取得一定进展。基于上述背景,本文综述了近年来金属基离子液体催化剂在生物质催化转化过程中的研究进展,重点介绍金属氯化物型、多金属氧酸盐型金属基离子液体在生物质基碳水化合物、木质素催化转化制备平台化学品,以及油脂催化（转）酯化制备生物柴油方面的研究进展;同时还综述了金属螯合物型金属基离子液体以及离子液体金属盐在生物质催化转化方面的研究工作。此外,对金属基离子液体在生物质资源方面的应用进行了总结和展望,并对金属基离子液体催化剂的设计提出建议,以期有助于生物质资源的开发和利用。     

Experimental test on a novel dual fluidised bed biomass gasifier for synthetic fuel production

This article presents a preliminary test on the 150 kW_th allothermal biomass gasifier at Mid Sweden University (MIUN) in Härnösand, Sweden. The MIUN gasifier is a combination of a fluidised bed gasifier and a CFB riser as a combustor with a design suitable for in-built tar/CH₄ catalytic reforming. The test was carried out by two steps: (1) fluid-dynamic study; (2) measurements of gas composition and tar. A novel solid circulation measurement system which works at high bed temperatures is developed in the presented work. The results show the dependency of bed material circulation rate on the superficial gas velocity in the combustor, the bed material inventory and the aeration of solids flow between the bottoms of the gasifier and the combustor. A strong influence of circulation rate on the temperature difference between the combustor and the gasifier was identified. The syngas analysis showed that, as steam/biomass (S/B) ratio increases, CH₄ content decreases and H₂/CO ratio increases. Furthermore the total tar content decreases with increasing steam/biomass ratio and increasing temperature. The biomass gasification technology at MIUN is simple, cheap, reliable, and can obtain a syngas of high CO + H₂ concentration with sufficient high ratio of H₂ to CO, which may be suitable for synthesis of methane, DME, FT-fuels or alcohol fuels. The measurement results of MIUN gasifier have been compared with other gasifiers. The main differences can be observed in the H₂ and the CO content, as well as the tar content. These can be explained by differences in the feed systems, operating temperature, S/B ratio or bed material catalytic effect, etc.     

Chemicals from biomass: synthesis of lactic acid by alkaline hydrothermal conversion of sorbitol

BACKGROUND: Currently, the ‘green chemistry’ philosophy is being increasingly adopted by the chemical industry and, therefore, new production procedures of valuable chemicals from biomass‐derived raw materials are being sought. In this work, the synthesis of lactic acid from sorbitol under alkaline hydrothermal conditions is investigated by analyzing the influence on conversions and yields of temperature, NaOH/sorbitol molar ratio (MR), initial sorbitol concentration (SC) and reaction time. RESULTS: A 100% sorbitol conversion and a maximum 39.5% yield of lactic acid on a carbon basis are obtained at 280 °C, 50 min, 1.0 mol L^?1 SC and 2.0 MR. Glyceraldehyde was the only identified intermediate while formic acid, acrylic acid, acetic acid, oxalic acid and sodium carbonate were identified as over‐oxidation products, all of them in very low yields with the exception of formic acid (16% yield at a MR of 4 and 280 °C). Several plausible conversion routes of sorbitol involving dehydrations, keto‐enol tautomerisms, reverse aldol condensations, aldol condensations, Cannizzaro reactions and oxidations are proposed. CONCLUSIONS: Considering the high number of parallel conversion routes as a consequence of high functionality of sorbitol, the 39.5% lactic acid yield obtained is a good result. Total carbon mass in all identified products only justifies, at most, 50% of that in sorbitol due to the coexistence of several conversion routes resulting in a large number of products other than lactic acid. Copyright © 2011 Society of Chemical Industry     

Catalytic hydrothermal treatment of pharmaceutical wastewater using sub- and supercritical water reactions

Application of subcritical and supercritical water technology for destruction of pharmaceutical compounds (carbamazepine, metoprolol and sulfamethaxazole) was investigated. The experiments were conducted inside batch reactor at a temperature ranging from 473 to 773 K and with different residence times of 5 to 50 min. The results show that carbamazepine, metoprolol and sulfamethaxazole are destructed by 90.27%, 99.99% and 98.84% after a 20 min exposure to 623 K, 673 K and 573 K, respectively. In comparison with the conventional methods of pharmaceutical waste treatment, the current technology provides a higher destruction efficiency (approximately 90–100%) which is achievable in shorter durations. NaOH and CuSO₄·5H₂O were also applied as catalysts in the temperature range of 473 K to 723 K. Comparing these catalysts, CuSO₄·5H₂O demonstrates a higher destruction efficiency, especially at lower temperatures. Based on the proposed pathway, the products of destructioncan be classified as environmentally-friendly compounds. The results show that this technology can be used as a green alternative for efficient removal of pharmaceutical compounds from wastewater streams.     

A review of the current state of biofuels production from lignocellulosic biomass using thermochemical conversion routes

The rapid increase in energy demand, the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector. Alternate renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil fuels.The conversion of lignocellulosic biomass to liquid(BtL) transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil fuels. Therefore, development of BtL systems is critical to increase the potential of this resource in a sustainable and economic way.Conversion of lignocellulosic BtL transportation fuels, such as, gasoline, diesel and jet fuel can be accomplished through various thermochemical processes and processing routes. The major steps for the production of BtL fuels involve feedstock selection, physical pretreatment, production of bio-oil, upgrading of bio-oil to transportation fuels and recovery of value-added products. The present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.     

生物质能利用技术研究进展

介绍了生物质能概念、开发利用生物质能的意义和价值以及其转化利用技术和现状。阐述了其开发前景。目前,生物质能的利用技术主要有直接燃烧法、生物化学法、热化学转化法、固体成型和生物柴油制取。我国生物质能利用的重点将是发展农林生物质发电、生物液体燃料、沼气及沼气发电、生物固体成型燃料技术四大领域。     

Catalytic hydrothermal treatment of pine wood biomass: effect of RbOH and CsOH on product distribution

Low‐temperature hydrothermal treatment of pine wood biomass was performed in the presence of RbOH and CsOH catalysts (280 °C for 15 min). The effect of the catalysts on the distribution of products and the volatility distribution of oxygenated hydrocarbons was studied in detail. Oxygenated hydrocarbons were extracted from the liquid and solid portions and analysed individually by gas chromatography/mass spectrometry. Catalytic (RbOH and CsOH) hydrothermal treatment of wood biomass produced mainly phenolic compounds and benzenediol derivatives. The use of RbOH and CsOH catalysts hindered the formation of char and favoured the formation of oil products, as observed previously for various other base catalysts. The volatility distribution of hydrocarbons (ether extract) was characterised by carbon‐normal paraffin (C‐NP) gram and it was found that the oxygenated hydrocarbons from all runs, including thermal, were distributed in the boiling point region of n‐C₆ to n‐C₁₇. Copyright © 2005 Society of Chemical Industry     

Catalytic hydrothermal conversion of cellulose over SnO2 and ZnO nanoparticle catalysts

The hydrothermal conversion of cellulose in the presence of nanometal oxide particles (SnO₂ and ZnO) was investigated in this study. Both catalysts were synthesized hydrothermally and characterized using TEM, FESEM-EDX, X-ray diffraction spectroscopy and BET (Brunauer, Emmett and Teller) methods. In order to reveal the effect of nano-scale catalysts, experiments were conducted using bulk (non-nano) metal oxide and pure cellulose without any catalyst. The hydrothermal conversion experiments were carried out in a micro autoclave at 300, 400, 500, 600 °C and 1 h reaction time. The compositions of the gaseous products and the aqueous phase were determined with various analytical techniques (GC, ion chromatography, HPLC, UV-vis). Contribution of carbon containing products to the carbon mass balance was also represented. The results indicated both nano and bulk ZnO and SnO₂ to have an effect on the water-gas shift reaction at varying temperatures. The water-gas shift reaction (WGS) proceeded fast at 300 °C in the presence of ZnO, while the rate of WGS was lower at 300 °C in the presence of SnO₂. Nano ZnO led to improved hydrogen yield, while ethane and propane were formed as a result of side reactions in the presence of nano and bulk SnO₂.     

Applications of hydrothermal electrolysis for conversion of 1-butanol in wastewater treatment

Hydrothermal electrolysis of organic compound in the presence of electrolyte was conducted for a woody biomass model compound. The reaction behavior of 1-butanol as a woody biomass model compound was studied in subcritical conditions at 200-250 °C and 8-12 MPa with a batch autoclave. The autoclave volume was 500 mL and equipped system with agitation stirrer, electric current control, electric heating and temperature control and a pressure gauge. The chemical species in aqueous products were identified by gas chromatography mass spectrometry (GC-MS) and quantified using gas chromatography flame ionization detector (GC-FID). The gaseous products were analyzed by gas chromatography with a thermal conductivity detector (GC-TCD). The effects of reaction temperature, pressure and applied constant current on the conversion process of 1-butanol were presented. The main products from the conversion of 1-butanol were butanal, butyric acid, hydrogen and carbon dioxide. Additionally, the values of reaction rate constant for butanal and butyric acid formation were calculated at 200 and 250 °C by kinetic study.     

完全连续式生物质水热转化系统的研发趋势

生物质水热转化技术具有原料适应性好、成本低、转化效率高的特点,使其具有未来工业化生产生物原油和化学品替代化石燃料的巨大潜力。本文综述了目前生物质水热转化连续式系统的研发进展,指出目前研发系统的主要环节部分仅水热反应器基本实现了连续化反应,而其他环节如原料进料、产物分离尚未实现连续化运行。分析表明,未来的生产模式要求具备效率高、能耗低、环保和节能等特点,才能实现商业化。本文提出了一套面向未来的完全连续式生物质水热转化系统模式。该系统可以实现包括生物质原料预处理、喂料/泵送、水热反应及产物分离各环节能完全连续化运行。同时,系统在产物分离过程中通过对关键水相产物反复循环回用进行热交换,实现更高的热效率实现节能;其次,通过水相产物的热量回收和水相产物循环回用实现过程水排放更加环保。通过分析实现此系统所需关键部件的研发进展,对该系统面对未来的商业化可能性提供了一种启示。     

Hydrogen production from allothermal biomass gasification by means of palladium membranes

One of the most promising technologies for the production of hydrogen is the use of a Palladium Membrane in order to separate hydrogen from a gas mixture coming from the allothermal biomass gasification process. At the TU München, an innovative allothermal gasifier called Biomass Heat Pipe Reformer (BioHPR) has been developed. This gasifier produces a hydrogen rich gas which can be further used for energy production. A Palladium Membrane can be installed in the gasifier in order to gain pure hydrogen from this gas mixture. This gas can be then used in applications which demand high purified hydrogen like for example Polymer Electrolyte Membrane Fuel Cells (PEMFC). The present paper describes the aforementioned gasification technology combined with a palladium filter and investigates the results from the simulation of these systems.     

生物质甘油催化转化为羟基丙酮

探索了生物质甘油在铜铬催化剂作用下催化转化为羟基丙酮的反应条件,采用乙醇为溶剂,考察了甘油浓度、催化剂用量和反应温度等因素的影响。较优反应条件:反应温度240℃,采用连续滴样的进样方式,甘油浓度80%,未还原的铜铬催化剂[n(Cu)∶n(Cr)=1]用量为原料质量的2.5%,甘油转化率和羟基丙酮选择性分别达到95.4%和89.9%。     

Upgrading of low rank coal and woody biomass mixture by hydrothermal treatment

Attempts to produce high-grade fuel from biomass and low rank coal are important from the viewpoint of renewable energy and the utilization of unused resources. In this paper, the authors reported on the hydrothermal treatment of biomass and low rank coal at 300 °C using a bench scale continuous apparatus and a batch autoclave. The results show that coalification takes place during the hydrothermal treatment of both the low rank coal and biomass, and the upgraded solid products show similar chemical compositions, gross calorific value and effective calorific value, independent of the mixing ratio. The solid product also becomes hydrophobic and unable to re-adsorb the lost moisture. The characteristics of the solid produced by the bench scale continuous apparatus can be predicted by the results of the batch process. Thermogravimetric analysis shows that the solid product has a wide-range of molecular weight but the thermally stable heavy molecules are found more in the treated coal as opposite to the thermally unstable light molecules, more of which are found in the treated biomass. This may correlate with that the solid product of higher biomass mixing ratio has a higher volatile matter content. Polymerization is synergistically promoted during mixed hydrothermal treatment of low rank coal and biomass.     

Catalytic conversion of waste plastics: focus on waste PVC

Effective waste management must address waste reduction, reuse, recovery/recycling and, as the least progressive option, waste treatment. The increase in plastic waste production is a serious environmental issue. Plastics consumption continues to grow and while plastic recycling has seen a significant increase since the early 1990s, consumption still far exceeds recycling. Waste plastic can, however, serve as a potential resource and, with the correct treatment, can be reused or serve as hydrocarbon raw material or as a fuel. PVC, highly versatile with many applications, is non‐biodegradable and has a high Cl content (56% of the total weight). Waste PVC incineration is highly energy demanding and can result in the formation of toxic chloro‐emissions with adverse ecological, environmental and public health impacts. The Cl component must be removed from any waste PVC derived gas or oil before it can be used. An overview of the existing waste plastic treatment technologies is provided with an analysis of the available literature on thermal and catalytic PVC degradation. Thermal degradation results in random scissioning of the polymer chains generating products with varying molecular weights and uncontrolled Cl content. There is a dearth of literature dealing with the catalytic dechlorination of PVC. A case study is presented to illustrate the role heterogeneous catalysis can play in PVC waste treatment. The efficacy of Pd/Al₂O₃ to promote PVC dechlorination is demonstrated, where a significant decrease (by up to a factor of 560) in the liquid fraction Cl content is recorded in addition to differences (relative to thermal degradation) in the gas phase product, i.e. higher C₁? C₄ content with preferential alkane formation. Copyright © 2007 Society of Chemical Industry     

二氧化碳催化转化在化学合成中的应用

二氧化碳的转化利用是C1 化学研究的前沿课题之一。综述了近年来CO2 催化转化在开发绿色合成工艺以及制备高附加值化工原料等方面的最新进展。     

生物炭催化生物质热化学转化利用的研究进展

热化学转化是生物质高值化利用技术中最具前景的技术之一,在此过程中引入催化剂可进一步提高反应速率及目标产物产率。生物炭由于具有较发达的孔隙结构和丰富的含氧官能团,近年来开始被应用于生物质热化学转化。本文简述了生物炭催化相关特性,介绍了生物炭作为催化剂催化生物质热化学转化为高品质生物油、气体燃料及催化焦油脱除的相关研究,总结了生物炭原位催化和非原位催化时的转化机理,讨论了生物炭活性位点作用与失活情况,描述了生物炭作为载体时与负载金属粒子间的相互关系,指出应进一步深化对生物炭催化生物质热化学转化利用机理的系统研究,通过调控生物炭物化结构和活性位点,以实现生物质热化学转化过程中较高的目标产物选择性、稳定性和经济性。     

活性炭催化剂臭氧催化氧化处理废水的研究进展

介绍了近年来国内外活性炭催化剂臭氧催化氧化的研究结果,对活性炭及金属负载型活性炭催化剂的反应机理进行了总结。讨论了非均相臭氧催化氧化过程中活性炭的主要作用,活性炭催化剂的表面物化性质、pH值、温度在臭氧催化氧化过程中的影响规律。并提出活性炭催化剂的降解机理以及催化剂性质与有机污染物的化学结构之间的关系还需要进一步的研究。     

Catalytic activity of pillared clays in methanol conversion

A number of pillared clay based catalysts have been used in methanol conversion and the obtained results related to the physico-chemical characteristics of the samples. Zr-PILCs samples have proven to be quite effective in dehydration to dimethyl ether and hydrocarbons due to their acidity and porosity. In special, well-pillared samples are suitable to obtain hydrocarbons. Doping with Cu does not improve dehydration due to the loss in acidity caused by Cu addition, but it renders the materials useful for methanol dehydrogenation. Cu/pillared clays have shown promising catalysts for methanol dehydrogenation to methyl-formate, despite the existence of interactions with the acid–base properties of the support, which contribute to dimethyl ether formation and degradation of methyl-formate to CO₂, CO and formaldehyde. X-ray diffraction, chemical analysis, N₂ and pyridine adsorption and XPS helped to understand the catalytic performance of the prepared catalysts.     

催化转化-生物降解法处理高浓度甲醛废水

提出了催化转化-生物降解法处理高浓度甲醛废水的新方法。研究发现,在温度为70℃,催化转化剂与甲醛摩尔比为1∶5,反应30 min,废水中甲醛去除率可达99.96%。预处理后的甲醛废水BOD5/CODcr值由0.12升至0.50,甲醛浓度<3 mg/L,大大提高了废水的可生化性。实验结果还表明,在采用生物降解法处理预处理后的甲醛废水过程中,当温度为35~40℃,pH值为7.0~7.5,水力停留时间(HRT)为9~12 h时,厌氧反应器有机负荷(OLR)为8.0~10.0 kg/(m3.d),好氧反应器OLR为1.0~2.0 kg/(m3.d),CODcr总去除率达到98.81%,出水COD<100 mg/L。该方法具有工艺简单、处理效率高和成本低等特点,有极高的实际应用价值。