Lignocellulosic stalks of three kinds of monocotyledonous (wheat, maize, and rice) and two kinds of dicotyledonous crops (rape and cotton) underwent 2% H2O2 pretreatment at pH 11.5 and 35 °C with 10% (w/v) biomass loading. Chemical composition analysis and biochemical methane potential (BMP) assays were carried out for biomass before and after pretreatment, in order to illuminate the impacts on bioenergy utilization efficiency caused by the alkaline hydrogen peroxide (AHP) pretreatment. The AHP pretreatment could recover about 90% of glucose and 80% of xylose, and remove around 50% and 30–40% of the lignin in monocotyledonous and dicotyledonous crop stalks, respectively. On the basis of volatile solid (VS) added into the pretreatment system, the observed BMP and digestible fraction of cotton stalk increased from 174 ± 12 mL CH4/g VS to 216 ± 6 mL CH4/g VS and from 36.0 to 44.7%, respectively. For the purpose of full utilization, the theoretical methane potentials of liquid waste generated from the AHP pretreatment were investigated. Theoretically, around 95 and 45 mL CH4/g VS from liquid wastes of monocotyledonous and dicotyledonous crop stalks could be produced, respectively. Besides, chemical compositional and structural changes showed that AHP pretreatment could break down esterified and etherified linkage in a lignocellulosic matrix.
Methanol at different mass concentrations (1, 6, 11, 16, 21 wt %) was added into crude bio-oil to upgrade oil properties. Indexes including pH value, water content and viscosity were measured regularly during a storage period of 91 days. GC-MS analysis was conducted before and after storage. An addition of 21 wt % methanol was found to improve the pH value from 2.97 to 3.88, and decrease the water content and viscosity after storage by 35.02% and 81.35%, respectively. The GC-MS analysis result convincingly showed that methanol could inhibit aging reactions such as polymerization and esterification which created new compounds in the oil. The FTIR and NMR analysis showed that methanol caused some structural changes in bio-oil.
Keywords: bio-oil, pyrolysis, stability, methanol
DOI: 10.3965/j.ijabe.20140703.010
Citation: Fei W T, Liu R H, Zhou W Q, Mei Y F, Yin R Z. Influence of methanol additive on bio-oil stability. Int J Agric & Biol Eng, 2014; 7(3): 83－92.
Abstract: Corn stalk samples from Anhui, Jiangxi and Shanghai were used as test materials. Their physical, chemical and thermo-chemical engineering characteristics were analyzed. The similarities and differences in properties of corn stalk from the three regions were determined using SIMCA-P and SPSS software in order to obtain a proper energy utilization method of corn stalk. The results show that the corn stalk from Shanghai has significant differences from the samples of Jiangxi and Anhui. In particular, the following properties of corn stalk from Shanghai such as the contents of cellulose, calcium (Ca), iron (Fe), crude ash, volatile matter, carbon (C), nitrogen (N), and oxygen (O) are significantly different from those of Jiangxi and Anhui samples (P smaller than 0.05). While other properties such as the contents of magnesium (Mg), copper (Cu), zinc (Zn), moisture, hydrogen (H), and sulfur (S) have no significant difference among samples of three regions. Compared with the corn stalk in Anhui and Jiangxi, the Shanghai samples are more suitable for the production of ethanol because of their higher ratio of cellulose to hemi-cellulose content. Because of its high content of ash and low calorific value, the Shanghai corn stalk is suitable for the gasification process instead of for direct combustion or bio-oil production. The research can provide a reference for raw material selection for biomass energy production and utilization.
Keywords: corn stalk, physical and chemical properties, bioenergy, principal components analysis, partial least squares discriminant analysis
DOI: 10.3965/j.ijabe.20140706.012
Citation: Wang L, Liu R H, Sun C, Cai W F, Tao Y W, Yin R Z, et al. Classification and comparison of physical and chemical properties of corn stalk from three regions in China. Int J Agric & Biol Eng, 2014; 7(6): 98－106.
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