蒸汽爆破技术在秸秆厌氧发酵中的应用

该文采用蒸汽爆破技术对秸秆进行预处理,探讨提高秸秆厌氧发酵产气量的新工艺.研究蒸汽爆破预处理的关键参数"爆破压力"和"保留时间"对秸秆厌氧发酵效果的影响.结果表明:蒸汽爆破预处理后的秸秆比未经预处理秸秆厌氧发酵的产气量提高34%～67.36%,蒸汽爆破预处理压力在3.0 MPa、保留时间为90 s时,每克干秸秆厌氧发酵沼气产量最大值达到304.72ml;蒸汽爆破预处理后,秸秆厌氧发酵的启动时间和发酵周期大大缩短.     

玉米秸秆液化制备生物高聚物材料的研究(英)

该研究旨在探讨低温生物质液化技术及液化产物应用的可能性。以玉米秸秆为原料在酸性、常压条件下快速液化成多羟基化合物，再以多羟基化合物为原料合成一系列的聚合材料。采用不同的有机溶剂，在稀硫酸的催化作用下，对不同的温度下生物质的液化效果进行研究。同时探讨了液化有机溶剂同生物质物料的混合比率对液化过程的影响。试验表明，碳酸乙烯酯比乙烯醇具有较高的液化率。优化试验结果表明，在较佳的液化效果下， 有机溶剂同玉米秆的混合比率为3∶1，反应温度160℃，稀硫酸浓度3%，反应时间2.5 h。液化产物经稀释、调节pH值、过滤、臭氧氧化一系列过程的处理后得到具有高活性多羟基聚合物。阐述了以多羟基聚合物制备各种生物聚合物材料如聚酯薄膜、聚胺酯泡沫和颗粒板的方法。聚酯薄膜是多羟基化合物上的羟基和多元酸上的羧基通过酯化反应形成的；聚胺酯泡沫通过多羟基化合物上的羟基和二异氰酸酯反应形成。研究表明以多羟基化合物和多元酸（酐）形成的聚酯型胶粘剂适合于制造颗粒板。     

秸秆合成气合成甲醇的动力学研究

为了实现农业废弃物转化为化工产品（燃料甲醇）,有效地利用生物质能,在直流流动等温积分反应器中,采用C301铜基催化剂, 催化剂粒度0.175 mm×0.147 mm,在压力为5 MPa,反应温度220～270 ℃,质量空速15532.67～26343.47 NL/（kgcat?h）条件下,对秸秆合成气合成甲醇动力学进行了研究。用Langmuir-Hinshelwood本征动力学模型和改进的高斯－牛顿法确定了该反应的动力学参数。残差分析和统计检验结果表明,所得到的本征动力学模型方程与试验数据吻合良好,为生物质（秸秆）气制备甲醇中试研究及甲醇合成反应器的设计提供了参考。     

Compositional analysis of water-soluble materials in corn stover

Corn stover is one of the leading feedstock candidates for commodity-scale biomass-to-ethanol processing. The composition of water-soluble materials in corn stover has been determined with greater than 90% mass closure in four of five representative samples. The mass percentage of water-soluble materials in tested stover samples varied from 14 to 27% on a dry weight basis. Over 30 previously unknown constituents of aqueous extracts were identified and quantified using a variety of chromatographic techniques. Monomeric sugars (primarily glucose and fructose) were found to be the predominant water-soluble components of corn stover, accounting for 30-46% of the dry weight of extractives (4-12% of the dry weight of feedstocks). Additional constituents contributing to the mass balance for extractives included various alditols (3-7%), aliphatic acids (7-21%), inorganic ions (10-18%), oligomeric sugars (4-12%), and a distribution of oligomers tentatively identified as being derived from phenolic glycosides (10-18%).     

Detoxification of corn stover and corn starch pyrolysis liquors by ligninolytic enzymes of Phanerochaete chrysosporium

Phanerochaete chrysosporium (ATCC 24725) shake flask culture with 3 mM veratryl alcohol addition on day 3 was able to grow and detoxify different concentrations of diluted corn stover (Dcs) and diluted corn starch (Dst) pyrolysis liquors [10, 25, and 50% (v/v)] in defined media. GC-MS analysis of reaction products showed a decrease and change in some compounds. In addition, the total phenolic assay with Dcs samples demonstrated a decrease in the phenolic compounds. A bioassay employing Lactobacillus casei growth and lactic acid production was developed to confirm the removal of toxic compounds from 10 and 25% (v/v) Dcs and Dst by the lignolytic enzymes, but not from 50% (v/v) Dcs and Dst. The removal did not occur when sodium azide or cycloheximide was added to Ph. chrysosporium culture media, confirming the participation of lignolytic enzymes in the detoxification process. A concentrated enzyme preparation decreased the phenolic compounds in 10% (v/v) corn stover and corn starch pyrolysis liquors to the same extent as the fungal cultures.     

考虑维护土壤功能的玉米秸秆能源开发潜力模拟

为获得可持续性的生物质能,在收集玉米秸秆时,需要考虑维护土壤功能的秸秆需求量。为维护土壤功能,结合相关文献所测定不同类型土壤的玉米秸秆保留量的最大值、中位值和最小值,研究设计了土壤玉米秸秆高保留、适度保留和低保留3种情景。针对不同情景,首先依据不同省份的土壤类型(黏土、壤土和沙土)和玉米种植面积,计算出玉米田地秸秆最小保留量(包括最大值、最小值和中位值);在此基础上,考虑可获取性及饲料、燃料等用途,得到可用于生物质能的玉米秸秆开发潜力;考虑农村秸秆生活用能可替代性和玉米秸秆热值,计算出不同替代率下秸秆能源开发潜力。通过研究发现,当考虑土壤功能时,假定未来秸秆燃烧完全替代,在低保留情景下,2020、2030和2050年的玉米秸秆潜力分别为2.79、2.82、3.96亿t。在高保留情景下,对应年份的秸秆可利用潜力分别为0.56、0.58、1.69亿t。考虑土壤秸秆保留量时,玉米秸秆潜力偏低。虽然考虑土壤秸秆保留量,减少了短期内生物质能开发潜力,但有利于农业和生物质能源的可持续性发展。过多的秸秆留田,不仅造成资源浪费,也会产生CH4等温室气体。研究结果为合理开发玉米秸秆资源提供了科学依据。     

不同添加剂对全株玉米和青玉米秸青贮饲料质量的影响

为了探讨不同添加剂对全株玉米和青玉米秸青贮饲料质量的影响,利用乳酸菌制剂和酶制剂单独或联合使用对原料进行青贮调制，并对开封后的青贮饲料进行了现场评定、实验室评定、生物评定和二次发酵试验。结果表明：不同添加剂处理后得到的全株玉米、青玉米秸青贮饲料的感官评定均优于对照组；在降低青贮饲料的NDF、ADF含量，提高动物的消化率上，乳酸菌制剂和酶制剂混合作用时的效果最显著；另外，乳酸菌1和乳酸菌1＋酶制剂1能够有效地抑制青贮饲料的二次发酵。     

适宜原料压实度改善玉米秸秆厌氧干发酵特性

干发酵原料中固形物含量高,结构疏松,原料的压实度直接关系到发酵罐的利用率和生产成本。为了探讨原料压实度对厌氧干发酵过程的影响,该文以玉米秸秆粉为试验材料,研究了不同固形物含量(TS)条件下原料压实度对厌氧干发酵产气特性及物料特性变化的影响,结果表明:相同TS下,随着压实度的增加,日产气量(基于可挥发性固形物,VS)峰值降低且出峰时间略有滞后;原料压实度对累积产气量、日产气量变化趋势以及甲烷体积分数的影响不明显。基于发酵罐容积计算产气量时,原料压实度与日产气量峰值、累积产气总量以及累积甲烷产量均呈显著正相关。不同TS条件下的原料压实度对厌氧干发酵过程的影响程度不同,TS含量越高原料压实度对产气量的影响越明显。TS为20%和25%时,逐层压实发酵罐的单位容积累积产气量比自然填料罐分别提高了37.1%和60.2%。当发酵料初始TS为20%时,原料压实度的增加可促使物料中形成连续的液相,改善物料层间的传质,从而使发酵料上下层间的差异减小。当发酵料初始TS提高到25%时,原料压实度增加对传质特性无明显影响。综上所述,在该试验研究范围内,提高原料压实度可以保证玉米秸秆厌氧干发酵产气过程的正常进行,且可以显著提高发酵罐的容积利用率。该研究对厌氧干发酵原料压实度与发酵特性之间的关系进行了初步探讨,以期为有效提高厌氧干发酵罐的产能能力提供参考。     

酶法复合脱毒提高玉米秸秆水解液丁醇发酵效率

利用玉米秸秆发酵产丁醇在生物质转化领域具有明显优势。为解除玉米秸秆水解液中多种有毒物质对微生物生长的抑制及对发酵产量的影响,该研究摒除常用的理化脱毒法,选择高效环保的酶法脱毒以实现溶剂高产。研究结果表明:通过优化漆酶和甲酸脱氢酶添加量以去除水解液中酚类和甲酸,单独添加漆酶5 U/m L、甲酸脱氢酶1 U/m L,水解液发酵的丙酮-丁醇-乙醇(acetone-butanol-ethanol,ABE,总溶剂)产量分别为1.03和1.11 g/L。再在活性炭的辅助下形成高效酶法复合脱毒体系,经复合脱毒处理的水解液发酵后丁醇产量达2.90 g/L,总溶剂ABE产量达到4.4 g/L,比未作处理的对照组发酵产量高出约5倍,实现了生物质的高效转化。可为玉米秸秆水解液发酵生产燃料丁醇提供参考。     

Short-term mesofauna responses to soil additions of corn stover biochar and the role of microbial biomass

Biochar additions have been suggested to influence soil microbial communities that, through a cascade effect, may also impact soil fauna. In turn, any direct biochar effects on fauna can influence microbial communities through grazing, physical fragmentation of organic debris (and biochar) and modifying soil structure. If biochar creates a favorable environment for soil microorganisms, it is also plausible for fauna to be attracted to such microbially enriched habitats. However, how soil fauna respond to biochar addition to soil and what are the main factors that drive their behavior has rarely been experimentally addressed. Therefore, the behavior of two mesofauna species was assessed as a result of corn stover biochar (slow pyrolysis at 600 °C) additions to a loamy temperate soil, after preincubation for 2, 17, 31 and 61 d, and related to variations in microbial biomass and activity. Microbial biomass increased by 5–56% and activity by 6–156% with increasing biochar rates for the different preincubation times. Over the incubation time, microbial biomass did not change or increased at most 15% with the different biochar rates, while in turn microbial activity decreased steadily (around 70–80% at day 61). Enchytraeids generally did not show avoidance or preference to biochar when provided with an alternative unamended soil, while collembolans often showed avoidance responses. However, collembolan avoidance to biochar decreased or disappeared in biochar mixtures with higher microbial biomass and water extractable NH₄-N content, agreeing with the plausible role of microorganisms to potentially attract soil fauna after biochar applications. Avoidance response was mainly explained by environmental preferences of the test species and not by any toxic effect of the biochar in this study. However, avoidance after the application of biochar may still need to be considered due to the potential negative impacts of individuals’ migration on soil ecosystem functioning.     

不同汽爆预处理对干玉米秸秆青贮效果的影响

为了扩大可用于青贮的玉米秸秆资源量,通过借鉴青贮、黄贮和汽爆玉米秸秆加工技术的优点,该文提出使用低强度汽爆对干黄玉米秸秆进行预处理,改进玉米秸秆青贮效果的方法。通过低强度汽爆（0.6～1.4 MPa,5 min）将玉米秸秆中的半纤维素适当降解为寡糖和单糖,增加玉米秸秆中的可溶性糖含量。调节质量含水率为70%,然后使用塑料袋密闭汽爆预处理后的玉米秸秆进行青贮。通过检测青贮过程中pH值、有机酸含量、氨态氮占总氮的比例等参数,并使用农业部青贮饲料质量评定标准对获得的青贮饲料进行评分。结果显示低强度汽爆（1.0 MPa,5 min）预处理可有效的增加干黄玉米秸秆中的可溶性糖含量,使饲料等级从“一般”到“优”。该方法可有效地增加可用于青贮的玉米秸秆资源量。     

玉米秸秆振动压缩过程的应力松弛试验

中国玉米秸秆资源非常丰富,由于本身松散、密度低的特点,其贮运成本较高,压缩致密是解决这一问题的最有效方法。在压缩过程中,玉米秸秆表现出的流变特性造成能耗高、压缩设备关键部件磨损严重以及生产率较低的问题,是制约其推广应用的主要瓶颈。针对这些问题,该文将振动引入玉米秸秆的压缩过程中,在自行设计的振动压缩试验系统上进行了揉碎后的玉米秸秆叠加振动与不加振动压缩应力松弛的试验研究,利用MATLAB软件的2阶指数方程对试验数据进行拟合,得到玉米秸秆振动压缩过程的2阶Maxwell应力松弛流变模型参数,其拟合度均大于0.9。基于流变模型,对应力松弛速率、应力松弛时间参数进行了分析,其结果为：压缩过程叠加振动,能够提高应力松弛速率、降低应力松弛时间以及成型块内部的残余应力,从而可降低再次压缩的压缩阻力、提高产品质量以及生产率,为解决现有成型设备高能耗低效率等问题提供了新的途径。     

玉米秸秆稀酸水解糖化法影响因子的研究

该文通过分析水解还原糖成分,研究了温度、时间、稀酸浓度、固形物含量对水解效率的影响;并结合残渣组分分析研究了稀酸水解过程中纤维素、半纤维素降解的规律.研究表明:在试验条件下玉米秸秆的水解主要以半纤维素为主,随着温度、稀酸浓度和水解时间的增加,纤维素的水解逐渐增强.当水解温度超过1000C后,水解得糖率迅速增加,超过110℃,纤维素开始水解;玉米秸秆的水解在前40 min就基本完成,过长的水解时间对水解效率的提高意义不大;水解的酸浓度应控制在1.5%左右;玉米秸秆在低固含物的条件下,水解效率相对较高.方差分析结果显示:温度、酸浓度对水解效率的影响最大,温度和固含物的影响次之,粒径的影响不显著;温度和酸浓度、温度和时间的交互作用对试验结果有影响显著.根据方差分析,最佳水解条件A3B2C3D1E1:温度125℃、时间80 min、稀酸浓度1.5%、固形物含量7.5%,在该条件下水解还原糖得率为32.71%.     

基于响应面法的玉米秸秆成型工艺优化

为了研究玉米秸秆成型过程中各参数之间的交互作用,获得最佳的工艺参数,该文采用5因素的响应面试验设计研究了原料水分(8%~24%)、温度(50~150℃)、压缩速度(10~50 mm/min)、压力(51.0~127.4 MPa)、保压时间(10~50 s)5个成型参数对玉米秸秆成型颗粒的松弛密度、Meyer强度以及压缩比能耗3个成型技术指标的影响,建立了响应面模型,结合成型燃料标准,获得了最佳的工艺参数,并对优化后的试验参数进行了试验验证。试验结果表明:在选取试验参数范围内,温度、原料水分、压力均会对技术指标产生较大影响;而压缩速度和保压时间所产生的影响相对较小。最优化的工艺参数(压力、温度、水分)为:4 k N(51.0 MPa)、110.8℃、17%,在该参数组合下的验证试验结果为:松弛密度为1031 kg/m~3,Meyer强度为27.1 N/m~2,比能耗为10.03 k J/kg。该研究可为秸秆生物质成型燃料制备产业提供参考。     

玉米秸秆和木屑及木钠混配成型工艺参数优化

为了研究玉米秸秆与木屑及木钠的混配成型特性,该文采用5因素的响应面中心组合设计,在WD-100KE型电子压力机上进行单颗粒压缩试验,研究了成型参数木屑质量分数(0~40)、木钠质量分数(2%~10%)、温度(40~160℃)、水分(4%~20%)、压力(1~9 k N)对成型指标松弛密度、比能耗、径向最大抗压力的影响。通过对试验数据的回归,建立了响应面模型,分析了参数间的交互作用,获得了较佳的成型参数,并进行了试验验证。结果表明:温度和水分、水分和压力对比能耗起显著交互作用;木钠质量分数和温度、温度和水分、水分和压力对径向最大抗压力起显著交互作用。较佳的参数为:木屑质量分数10.15%,木钠质量分数8%,温度95.83℃,水分15.83%,压力3 k N,验证试验参数修正为:木屑质量分数10%,木钠质量分数8%,温度96℃,水分16%,压力3 k N,响应指标结果为:松弛密度1 054 kg/m3、比能耗8.02 k J/kg、径向最大抗压力685N,与预测值误差值在8%以内,可为相关生产提供理论参考。     

发泡剂对玉米秸秆基聚氨酯泡沫性能影响

以玉米秸秆的液化产物为原料制备聚氨酯泡沫材料,通过改变发泡剂——水的用量,利用万能材料试验机、差失量热扫描仪（DSC）和热重分析仪（TGA）,研究了水用量对聚氨酯泡沫材料机械特性和热特性的影响。研究结果表明,随着水用量的增加,材料的拉伸强度和断裂伸长率都是先增加后降低,最大值分别为1.87 MPa和189.7%;材料的起始热分解温度逐渐降低,玻璃化转变温度逐渐增加,转变温度范围变宽。改变水用量可以得到不同性质的聚氨酯泡沫材料。     

Porosity and its effect on the digestibility of dilute sulfuric acid pretreated corn stover

Enzyme accessibility has been proposed as a limiting factor in the enzymatic conversion of the cellulose in biomass to glucose. Prior work has shown a strong correlation between porosity, measured as the change in the volume of pores accessible to a cellulase-sized molecule, and the initial digestibility of biomass pretreated by various methods. The goal of this work was to determine if porosity was one of the factors governing the overall enzymatic digestibility of the cellulose in dilute acid pretreated biomass. The porosity of wet pretreated corn stover was determined using the methods of solute exclusion and 1H nuclear magnetic resonance (NMR) thermoporometry. The solute exclusion method identified differences in the accessible pore volume of the pretreated samples compared to untreated corn stover; however, only very small differences in porosity were observed among samples pretreated with a range of severities, giving ethanol yields from 70 to 96%. No correlation was found between the volume accessible to an enzyme-sized molecule (diameter estimated to be 51 A) and the digestibility of the cellulose in dilute acid pretreated corn stover. 1H NMR thermoporometry was used to measure the amount of water in pores ranging from 20 to 200 A. As was the case for the solute exclusion method, a difference was observed in the pore volume of untreated and acid pretreated corn stover, but no significant differences in pore volume were measured for the different pretreated samples.