芒草稀硫酸水解工艺条件的正交实验

芒草含有80%以上的可降解的纤维素和半纤维素,仅含有19%的不被酸降解的苯环化合物,木质素,适于作为生产燃料乙醇的原料。通过对芒草稀酸水解工艺的正交实验研究,探讨了反应时间、硫酸浓度、原料与硫酸的固液比等因素对纤维素、半纤维素降解为葡萄糖、木糖及总糖含量的影响。结果表明:在121℃条件下,对于纤维素,影响葡萄糖产量的主要因素是硫酸浓度;而对于半纤维素,1.5%的硫酸就可使之降解完全;但在酸浓度较高时,会产生葡萄糖、木糖以外的杂质。     

纤维素稀酸水解的试验研究

阐述了生物质水解的研究背景和发展现状，并在间歇反应器上，对极低浓度酸条件下纤维素的水解进行了研究。以浓度小于0．1％的H2SO4为催化剂，在215℃条件下，得到了较高的还原糖产率和纤维素转化率对于不同停留时间对反应的影响进行了研究，得出不同酸浓度下获取还原糖的最佳停留时间、利用水解生成的糖可通过后续发酵制取燃料酒精等液体燃料，有利于缓解能源危机和环境压力。     

亚铁离子催化棉纤维常压两段酸水解研究

以脱脂棉作为纤维素模型物,以总还原糖得率为考察指标,在纤维素常压两段酸水解的基础上,对FeSO4·7H2O助催化剂进行了研究,对浓硫酸质量分数、酸固比(ml/g,下同)、预处理温度、预处理时间、水固比(质量比,下同)、助催化剂添加量6个水解条件进行分析。单因素试验表明,当浓硫酸质量分数为60%、预处理温度为60℃、预处理时间为3h、酸固比为12∶1、水固比为180∶1、助催化剂添加量为0.23%时,水解效果较好,总还原糖得率可达15.18%。与未添加催化剂的常压两段酸水解相比,添加催化剂后,Fe2+能够在一定程度上促进纤维素的水解,并能有效抑制葡萄糖的降解,总还原糖得率可提高将近30%。     

超低浓度马来酸催化水解纤维素的机理研究

将超低浓度马来酸应用于纤维素水解研究,对间歇条件下最优工况的产物和超低浓度硫酸水解纤维素产物与前人结果进行比较,初步探讨了马来酸水解纤维素的机理。试验在高温高压反应釜中进行,液固比为20∶1,转速为500 r/min,反应压力为4 MPa,改变温度和酸浓度,多点采样,结果发现,超低马来酸催化滤纸纤维素水解产糖效果较好,糠醛类降解产物明显少于硫酸催化。推导整合马来酸催化纤维素水解的基本原理,与常规无机酸催化相比,马来酸水解可同时遵循拟糖苷酶催化与一般酸催化机理,并能通过自身特性有效抑制还原糖的降解,从而获得较高的糖收率。     

无外加催化剂条件下甜高粱渣汽爆预处理研究

甜高粱茎秆压榨提汁后产生的残渣是生产纤维素乙醇的优良原料。预处理是纤维素乙醇生产过程的关键环节之一。文章对甜高粱压榨剩余残渣进行了无外加催化剂的汽爆预处理研究,通过比较不同反应条件下的预处理效果、发酵抑制物糠醛的生成,及残渣水解效果,确定了最佳预处理工艺:压力为2.4 MPa,时间为120 s,在此条件下,预处理后残渣中纤维素含量达到44.71%,纤维素水解率为82.72%,而在预处理过程中糠醛产生量为1.62 mg/g,对后期酵母发酵影响小。     

超低马来酸水解纤维素的试验研究

以定量滤纸为纤维素模化物,在3种超低酸浓度和4种温度下进行了马来酸水解的多点取样实验,以还原糖收率为指标得到较佳工况,并进一步通过间歇实验确定酸浓度0.1%、液固比20:1、温度220℃、压力4MPa、搅拌速率500r/min、反应时间55min为较优工况,可得到还原糖收率、还原糖转化率和原料转化率分别为32%、66%和48%。硫酸水解的较佳工况比较,发现马来酸存在下还原糖降解较弱,糠醛类的相对含量比硫酸存在时减少24.57%(48.22%:72.79%)。马来酸水解纤维素产糖多为聚糖;残渣依然具有纤维素特性,但结晶度较原料降低17%,对后续的酶解及发酵有利。     

水热条件下CO2催化棉纤维水解过程的研究

纤维素是地球上丰富的可再生资源之一,通过水解纤维素可以获得许多有价值的化合物.以脱脂棉为纤维素模型化合物,研究了水热条件下CO2催化脱脂棉的水解过程.试验结果表明:在水热条件下,CO2可以有效地催化脱脂棉进行水解反应.DSC分析表明:水解后棉纤维的软化点向高温区移动,即非晶态纤维减少;SEM图显示:在无CO2催化条件下,脱脂棉的水解反应主要是非晶态纤维的水解;在CO2催化条件下,晶态纤维素也可以被有效地水解.此外,还考察了温度、CO2压力和停留时间对棉纤维水解过程的影响.     

木质纤维素两步稀酸低温水解研究

为了降低水解液中抑制剂的浓度,对木质纤维素采用两步稀酸低温水解,通过对两步稀酸水解中重要参数(温度,反应时间,硫酸浓度)的研究,得到第一步水解的最佳条件为:温度135℃,反应时间2h,硫酸1.5%;第二步水解最佳条件为:温度135℃,反应时间2h,硫酸3.0%。以秸秆为原料得到的糖浓度可达5%。采用嗜鞣管囊酵母对水解软木所得水解液进行乙醇发酵实验,24h乙醇产率为0.41g/g,达到最大理论产率的80.4%。乙醇发酵实验证明,两步稀酸低温水解物对乙醇发酵没有抑制作用。     

微波促纤维素超稀酸水解研究

将微波加热方法应用于纤维素超稀酸水解。研究了在微波辐射及加压条件下纤维素的超稀酸水解机理,并对超稀硫酸和超稀马来酸的催化水解效果进行了对比研究,通过正交试验考查了固含量、酸浓度、反应压力、反应时间及微波功率对还原糖得率的影响。试验结果表明,对于纤维素超稀酸水解制备还原糖的转化,微波加热法可降低反应压力,缩短反应时间,提高水解液还原糖浓度;在优化工艺条件下,超稀马来酸的催化效果优于超稀硫酸。对纤维素水解残余物的红外分析表明,超稀硫酸和超稀马来酸催化水解残余物均保留了较好的纤维素特征。     

餐厨垃圾制备燃料乙醇二级催化水解反应的研究

餐厨垃圾的水解过程是餐厨垃圾制备燃料乙醇的关键步骤。研究采用两级催化水解技术,较好地解决了淀粉和纤维素协同、经济、高效水解糖化的难题,以餐厨垃圾为原料,研究复合催化剂、酸浓度、水解温度对水解效果的影响。结果表明,使用复合催化剂且浓度为0.5%H2SO4+0.01%助催化剂,在一级水解温度为120℃和二级水解温度为180℃时得到的水解效果较好。     

酶酸联合水解玉米秸秆的实验研究

开发了一种通过酸酶联合水解处理玉米秸秆以得到可发酵单糖的工艺方法,进行了稀硫酸预处理玉米秸秆的研究。得到最佳的工艺条件,木糖收率达到84.90%。用纤维素酶水解酸处理过的玉米秸秆,考察了pH值、温度、时间对酶水解率的影响,结果表明:酶解温度为50℃,pH值为4.8,水解时间为60h时,酶水解率达到91.71%。该工艺达到了节能高效地转化玉米秸秆为可发酵单糖的目的。     

尿素制氨工艺在SCR烟气脱硝工程中的应用

介绍了SCR烟气脱硝工程中几种尿素制氧工艺的系统及特点，对其在实际工程中的应用进行了比较，并提出工程应用中应注意的问题。     

Hydrogen production from acid and enzymatic oat straw hydrolysates in an anaerobic sequencing batch reactor: Performance and microbial population analysis

Feasibility of hydrogen production from acid and enzymatic oat straw hydrolysates was evaluated in an anaerobic sequencing batch reactor at 35 °C and constant substrate concentration (5 g chemical oxygen demand/L). In a first experiment, hydrogen production was replaced by methane production. Selective pressures applied in a second experiment successfully prevented methane production. During this experiment, initial feeding with glucose/xylose, as model substrates, promoted biomass granulation. Also, the highest hydrogen molar yield (HMY, 2 mol H₂/mol sugar consumed) and hydrogen production rate (HPR, 278 mL H₂/L-h) were obtained with these model substrates. Gradual substitution of glucose/xylose by acid hydrolysate led to disaggregation of granules and lower HPR and HMY. When the model substrates were completely substituted by enzymatic hydrolysate, the HMY and HPR were 0.81 mol H₂/mol sugar consumed and 29.6 mL H₂/L-h, respectively. Molecular analysis revealed a low bacterial diversity in the stages with high hydrogen production and vice versa. Furthermore, Clostridium pasteurianum was identified as the most abundant species in stages with a high hydrogen production. Despite that feasibility of hydrogen production from hydrolysates was demonstrated, lower performance from hydrolysates than from model substrates was obtained.     

反应条件对松木稀酸水解过程的影响

以松木屑为原料,稀盐酸为催化剂,探索液固比、反应温度及催化剂浓度等影响因素对可降解糖产率的影响。实验结果表明:在120℃、液固比为6∶1、盐酸浓度为0.5%时,还原性糖产率达到最大。     

Effect of cornstalk hydrolysis on photo-fermentative hydrogen production by R. capsulatus

Cornstalk is a typical cellulose material, which can be used by photo-fermentative H₂ production after pretreatment. However, the pretreatment methods have different influence on photo fermentation. In this study, 25.0 g cornstalk was pretreated by HCl/NaOH/cellusase. The hydrolysis rates increased from 45.51% by ddH₂O-treatment to 60.79% by diluted HCl-treatment and 51.6% by NaOH-treatment. The corresponding reducing sugar yields were 0.13 g/g, 0.42 g/g and 0.01 g/g, respectively. Enzymatic treatment enhanced the corresponding cornstalk hydrolysis rates to 50.81%, 67.60% and 64.10% with reducing sugar yields of 0.22 g/g, 0.62 g/g and 0.26 g/g. The sorts and concentrations of carbon source for H₂ production vary among different hydrolysates. Photo-fermentative H₂ production of strain R. capsulatus JL1 and mutant JL1601 (cheR2^-) with hydrolysates were investigated. The maximum H₂ yield of 123.8 ± 14.2 mL/g by strain JL1 was obtained from alkali-enzyme pretreated cornstalk, while the H₂ yield of 224.9 ± 5.2 mL/g by mutant JL1601 (cheR2^-) was obtained with acid-enzyme hydrolysate as the substrates. Meanwhile, the alkali pretreated cornstalk was the worst for photo-fermentation of both strain JL1 and mutant JL1601 (cheR2^-). Nevertheless, the highest substrate conversion efficiencies for both strains were obtained from ddH₂O-pretreated hydrolysate. Two-step pretreated hydrolysates were more beneficial to H₂ production for mutant JL1601 (cheR2^-) but not for strain JL1.     

Smart construction of oxidized-Ti3C2TX stabilized Rh nanoparticles for remarkable improving the catalytic performance for ammonia borane hydrolysis

Supported Rh nanoparticle (NP) catalysts have been widespread investigated for hydrogen production from ammonia borane (AB) hydrolysis. However, it is still challenging to develop an efficient strategy to improve the catalytic performances of supported Rh NP catalysts considering the high-cost and limited reserve of Rh. To overcome this limitation, we propose a facile but effective method to significantly improve the catalytic performance of Rh NPs by using oxidized-Ti₃C₂T_x (o-Ti₃C₂T_x) as a NP support. The systematic investigation results suggest that well distributed and ultrasmall Rh NPs with a diameter of 2.60 nm are successfully loaded on the o-Ti₃C₂T_x surface, which can be used as excellent catalysts for hydrogen release from AB hydrolysis. The corresponding turnover frequency (TOF) of 2021 min⁻¹ and activation energy of 18.7 kJ/mol are achieved, which are superior to that of Rh NPs supported on a fresh Ti₃C₂T_x support and most of previous reported Rh NP catalysts. Additionally, the reusability test shows that Rh/o-Ti₃C₂T_x can maintain 53% of the initial catalytic activity after the fifth run. This study opens a new avenue to adjust the catalytic activity of metal NP catalysts for use in field of catalytic applications.     

木屑纤维素酶水解条件的试验研究

采用正交试验法研究了稀盐酸预处理木屑的最优条件:反应温度为105℃,反应时间为3 h,用质量分数为2%的HCl预处理后,半纤维素质量分数降低了78.4%,木质素降低了29.3%.用纤维素酶水解预处理过的木屑,考察了pH值、温度、时间对酶水解率的影响,结果表明:酶解温度为50℃,pH值为4.8,纤维素酶液用量为2 ml/g,水解时间为48 h时,酶水解率达到76%,纤维素质量分数降低了65.4%.     

Optimization of dilute acid and enzymatic hydrolysis for dark fermentative hydrogen production from the empty fruit bunch of oil palm

Pretreatment of the empty fruit brunch (EFB) from oil palm was investigated for H₂ fermentation. The EFB was hydrolyzed at various temperatures, H₂SO₄ concentrations, and reaction times. Subsequently, the acid-hydrolysate underwent enzymatic saccharification under various temperature, pH, and enzymatic loading conditions. Response surface methodology derived the optimum sugar concentration (SC), hydrogen production rate (HPR), and hydrogen yield (HY) as 28.30 g L⁻¹, 2601.24 mL H₂ L⁻¹d⁻¹, and 275.75 mL H₂ g⁻¹ total sugar (TS), respectively, at 120 °C, 60 min of reaction, and 6 vol% H₂SO₄, with the combined severity factor of 1.75. Enzymatic hydrolysis enhanced the SC, HY, and HPR to 34.52 g L⁻¹, 283.91 mL H₂ g⁻¹ TS, and 3266.86 mL H₂ L⁻¹d⁻¹, respectively, at 45 °C, pH 5.0, and 1.17 mg enzyme mL⁻¹. Dilute acid hydrolysis would be a viable pretreatment for biohydrogen production from EFB. Subsequent enzymatic hydrolysis can be performed if enhanced HPR is required.     

Sustainable hydrogen production via LiH hydrolysis for unmanned air vehicle (UAV) applications

In the current study, an experimental approach for the further understanding of the LiH hydrolysis reaction for hydrogen production is considered. The experimental work has been undertaken under small scale conditions by utilising fixed bed reactors. The hydrolysis reaction has been studied at several oven temperatures (150 °C, 300 °C and 500 °C). The favourable driving potentials for the hydrolysis reactions were identified by the utilisation of the Gibbs free energy analysis. The main outcome of the study is the deceleration of the reaction pace due to the formation of the by-product layers during the reaction. At the initial stage, due to the contact of steam with the unreacted and fresh LiH surface, the reaction proceeds on a fast pace, while the formation of the layers tends to decelerate the diffusion of steam into the core of material, forcing the production step to be slower. The hydrogen yield was found to be more than 90% of the theoretical value for all the reaction temperatures. Finally, a scenario of a hybrid-electric propulsion system for Unmanned Aerial Vehicles (UAVs) including Li-ion battery, Proton Membrane Fuel Cell (PEMFC) and an on-board hydrogen production system based on LiH hydrolysis is introduced and studied.     

Experimental study of gaseous effluent and solid conversion in a fluidized bed hydrolysis reactor for hydrogen production

In this paper, new experimental data is presented for the hydrolysis of steam with CuCl₂ particles, in a high-temperature fluidized-bed reactor, which is a critical component of the Cu–Cl hydrogen production cycle. Results are obtained from large engineering-scale equipment built to perform the hydrolysis reaction using steam and CuCl₂. Experimental facilities are utilized for a boiler and superheater to supply steam for the endothermic reaction to proceed. This paper provides new insight into the hydrolysis operation by examining various issues involving the reaction rate and integrating the hydrolysis reactor into the Cu–Cl cycle. The results indicate a 40% reduction in the experimental reaction rate, during the initial 30 min of the reactor operation, as physical rate-controlling resistances develop in the process. This paper analyzes the process, in terms of chemical reaction rates, and limiting the physical resistances to efficient reaction rates within the reactor, as needed for the Cu–Cl cycle to become more economically competitive against other methods of hydrogen production.