Effect of higher alcohols on the performances of a 1%Rh/MgAl2O4/Al2O3 catalyst for hydrogen production by crude bioethanol steam reforming

The object of the present study was to study the role of alcohols, which are the major impurities found in a crude bioethanol feed, on the catalytic performances of a 1%Rh/MgAl₂O₄/Al₂O₃ catalyst during ethanol steam reforming. The alcohols studied were methanol, propan-1-ol, butan-1-ol, pentan-1-ol, isopropanol, 2-methyl propan-1-ol, 3-methyl butan-1-ol. Whereas the presence of 1% of methanol in the ethanol and water feed only slightly increased the hydrogen yield, the addition of the same amount of higher alcohols strongly decreased the stability of the catalyst during ethanol steam reforming, with a direct impact on the ethanol conversion and the hydrogen yield. It was shown that the deactivation is increased when the amount of carbon atoms in the molecule is increased. This effect is more pronounced in the presence of branched alcohols compared to the linear ones. It was demonstrated by studying the steam reforming of these higher alcohols that they are dehydrated to the corresponding olefin. The strong deactivation of the catalyst observed in the presence of higher alcohols was explained in terms of coke deposition.     

Submicrometer‐Sized ZIF‐71 Filled Organophilic Membranes for Improved Bioethanol Recovery: Mechanistic Insights by Monte Carlo Simulation and FTIR Spectroscopy

Template‐free self‐assembly synthesis of nano‐sized metal‐organic frameworks (MOFs) is of particular interest in MOF research since organized nanostructures possessing distinctive properties are useful for many advanced applications. In this work, the facile room temperature synthesis of robust submicrometer‐sized ZIF‐71 crystals with different particle sizes (140, 290, or 430 nm), having a high permanent microporosity (S_BET = 827 cm² g^?1) and synthesis yield up to 80% based on Zn on a gram‐scale, is reported. These small ZIF‐71 particles are ideal filler for the fabrication of thinner and homogeneous polydimethylsiloxane (PDMS) based mixed matrix membranes (MMMs) with excellent filler dispersion and filler‐polymer adhesion at high loading up to 40 wt%, as confirmed by scanning electron microscopy. Pervaporation tests using these submicrometer‐sized ZIF‐71 filled MMMs show significant improvement for bioethanol recovery. Interesting phenomena of i) reversible ethanol‐ethanol hydrogen interaction in the ethanol liquid‐phase and ii) irreversible hydrogen interaction of ethanol and –Cl functional group in the α‐cages and octagonal prismatic cages of ZIF‐71 in ethanol vapor‐phase are discovered for the first time by a Fourier transform infrared spectroscopy (FTIR) study. In full agreement with molecular simulation results, these explain fundamentally the ZIF‐71 filled MMMs pervaporation performance.     

Bioethanol production from bio‐ organosolv pulps of Pinus radiata and Acacia dealbata

Wood chips from Pinus radiata and Acacia dealbata were pretreated with the white‐rot fungi Ceriporiopsis subvermispora and Ganoderma australe, respectively, for 30 days at 27 °C and 55% relative humidity, followed by an organosolv delignification with 60% ethanol solution at 200 °C for 1 h to produce pulps with high cellulose and low lignin content. Biotreatment for 30 days was chosen based on low weight and cellulose losses (lower than 4%) and lignin degradation higher than 9%. After organosolv delignification, pulp yield for P. radiata and A. dealbata pulps was 45–49% and 31–51%, respectively. P. radiata bio‐pulps showed higher glucan (93%) and lower lignin content (6%) than control pulps (82% glucan and 13% lignin). A. dealbata bio‐pulps also showed higher glucan (95%) and lower lignin content (2%) than control pulps (92% glucan and 4% lignin). Pulp suspensions at 2% consistency were submitted either to separate enzymatic hydrolysis and fermentation (SHF) or simultaneous enzymatic saccharification and fermentation (SSF) for bioethanol production. The yeast Saccharomyces cerevisiae was used for fermentation. Glucan‐to‐glucose conversion in the enzymatic hydrolysis of control and bio‐pulps of P. radiata was 55% and 100%, respectively, and it was 100% for all pulp samples case of A. dealbata. The highest ethanol yield (calculated as percentage of theoretical yield) during SHF of P. radiata control and bio‐pulps was 38% and 55%, respectively, and for A. dealbata control and bio‐pulps 62% and 69%, respectively. The SSF of P. radiata control and bio‐pulps yielded 10% and 65% of ethanol, respectively, and 77% and 82% for A. dealbata control and bio‐pulps, respectively. In wood basis, the maximum conversion obtained (g ethanol per kg wood) in SHF was 37% and 51% (for P. radiata and A. dealbata pulps, respectively) and 44% and 65% in SSF (for P. radiata and A. dealbata pulps, respectively) regarding the theoretical yield. The low wood‐to‐ethanol conversion was associated with low pulp yield (A. dealbata pulps), high residual lignin amount (P. radiata pulps) and the low pulp consistency (2%) used for SHF and SSF. Copyright © 2007 Society of Chemical Industry     

Modelling the metabolic characteristics of proteins in dairy cattle from co-products of bioethanol processing: comparison of the NRC 2001 model with the DVE/OEB system

BACKGROUND: Co‐products from bioethanol processing include wheat dried distillers grains with solubles (DDGS), corn DDGS, blend DDGS (e.g. wheat/corn at 70:30, 60:40 or 50:50 w/w), triticale DDGS, barley DDGS and pea DDGS. The objective of this study was to compare two systems, the DVE/OEB system versus the NRC 2001 model, in modelling the metabolic characteristics of proteins in dairy cattle from different types of co‐products (DDGS) from different bioethanol processing plants. RESULTS: The predicted values from the NRC 2001 model were 10% higher (P < 0.05) in truly absorbable rumen‐synthesised microbial protein in the small intestine, 10% lower (P < 0.05) in truly absorbed rumen‐undegraded feed protein in the small intestine, 30% lower (P < 0.05) in endogenous protein and 2% lower (P < 0.05) in total truly absorbed protein in the small intestine than the predicted values from the DVE/OEB system. However, no significant difference was detected in terms of the degraded protein balance between the two models (P > 0.05). CONCLUSION: The sensitivity of the two models in detecting differences among DDGS types and between bioethanol plants was similar. The two models coincided in the superior protein value of blend DDGS as well as in the more optimal degraded protein balance (DPB) for corn DDGS. Although the differences between the DVE/OEB system and the NRC 2001 model were significant (P < 0.05) for most outputs owing to differences in some of the concepts and factors used in modelling, the correlations between total truly absorbed protein (DVE) and metabolisable protein (MP) values and between degraded protein balances (DPB^OEB vs DPB^NRC) were also significant (P < 0.05). Copyright © 2010 Society of Chemical Industry     

花生壳发酵生产生物乙醇可行性研究

研究以花生壳为原料,采用超临界水一步法获得可发酵糖液,并通过混合菌种将可发酵糖液转化为生物乙醇的工艺方法。不仅使农业废弃物得到综合利用,同时,也获得了良好的经济效益和环境效益。     

蔗渣纤维素乙醇的预处理技术研究进展

从蔗渣的物化特性及预处理的必要性出发,综述了近年来国内外预处理蔗渣方面发展的不同技术途径(包括物理法、化学法、生物法和联合法)及其研究进展,对各种技术的作用效果和特点进行了总结和对比分析,并对蔗渣预处理技术的发展方向予以展望。蔗渣作为糖厂的主要副产物,具有量大、集中且纤维含量高等特点,是生产第二代生物乙醇的重要潜在原料之一,对其进行有效预处理是利用其制取生物乙醇的关键,直接影响着后续的酶解糖化和乙醇发酵效果。     

发酵抑制物对葡萄糖发酵产乙醇的影响

在纤维素乙醇研究中,木质纤维原料在酸性预处理过程中会产生甲酸、乙酸、乙酰丙酸、糠醛和5-羟甲基糠醛等发酵抑制物,这些发酵抑制物会影响葡萄糖发酵生产乙醇的收率。本文考察了发酵液中各种发酵抑制物含量对高温超级酿酒酵母发酵乙醇收率的影响。研究结果表明,多种发酵抑制物的协同作用对乙醇发酵的影响要高于单一种类发酵抑制物对乙醇发酵的影响。发酵液中发酵抑制物总量一般控制在3.0g/L以内时,对葡萄糖发酵生产乙醇的抑制作用不明显。     

Bioethanol production from tuber crops using fermentation technology: a review

Bioethanol, an alcohol produced by fermentation of plant biomass containing starch and sugars by micro-organisms, considered as a dominant form of fuel for future. Production of this renewable fuel, especially from starchy materials such as tuber crops, holds a remarkable potential to meet the future energy demand because of its high production and comparitively less demand for use as food and fodder. This review focuses on the world bioethanol production scenario from various tuber crops, namely cassava, sweet potato, potato, yam, aroids, sugar beet, etc., fermentation techniques and micro-organisms used in fermentation process along with its future prospects. The advances in metabolic pathway engineering and genetic engineering techniques have led to the development of micro-organisms capable of efficiently converting biomass sugars into ethanol. Several biotechnological tools that are also available for the improvement of microorganisms to meet the harsh environments typically met with certain industrial fermentation process are also discussed.