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Ezomatsu wood blocks were acetylated in a mixture of acetic anhydride and acetic acid containing excess potassium acetate
(KAc). The mixture method enabled rapid acetylation at 120°C: a 20% weight gain (weight percent gain; WPG) was achieved within
30 min while the WPG did not exceed 18% after 120 min of conventional uncatalyzed acetylation. At 40°C, however, a satisfactory
WPG was not achieved with the mixture method because both the wood swelling and KAc concentration in the reagent solution
were limited at that temperature. In addition, the antiswelling efficiency attained by the mixture method was irregularly
low, probably because of nonuniform reaction involving shrinkage of the cell lumina. These results suggest that the mixture
method is not advantageous for low-temperature acetylation, whereas it enables simple and rapid acetylation at high temperature. 相似文献
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Cherif Ibrahima Khalil DiopHai Long Li Bi Jun Xie John Shi 《Industrial Crops and Products》2011,33(2):302-309
By activating corn starch with acetic acid and using acetic anhydride as an esterifying agent, starch acetates with increasing degrees of substitution were obtained using microwave assistance when the amount of iodine varied from 0.5 to 1.75 mmol. The study of Fourier Transform Infrared (FT-IR) spectra, X-ray diffraction pattern, thermal properties, granule morphology, water absorption and solubility, revealed important changes on the physical properties of the obtained products related to the increase of the iodine content. As shown by the scanning electron microscope (SEM), a specific structure on the granule surface was discerned for each amount of iodine. By its exo-corrosive action on starch, iodine indirectly induced loss of crystallinity, decrease of the glass transition and melting temperatures, and a progressive reduction in the water absorption and water solubility index of the modified products. Starch esters with better hydrophobicity and good processability for bio-based material applications were synthesized. Alternatively, the variation in the concentration of the iodine could also be of interest in special purposes, in which starch granules with controlled surface porosity are needed. 相似文献
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[目的]为冬枣保鲜提供科学依据。[方法]研究了以氯酸钠和硫酸为原料,尿素为还原剂,MnO2/Cr2O3为催化剂制备二氧化氯的方法。并用该方法制备了低温型缓释二氧化氯制剂1、2号,比较了其对低温贮藏冬枣的保鲜效果。[结果]经正交试验优化后,制备二氧化氯的最佳工艺为:温度70℃,酸度6mol/L,m(MnO2)∶m(Cr2O3)=3∶1,n(NaClO3):n(CO(NH2)2)=2.5∶1,此条件下,二氧化氯产率达95%,纯度达95%以上。放置缓释二氧化氯制剂后,冬枣的可滴定酸和Vc含量均高于对照组,失重率、呼吸强度和乙醇含量均低于对照组。二氧化氯释放量大的1号缓释剂的保鲜效果好于释放量小的2号缓释剂。[结论]缓释二氧化氯制剂可有效提高冬枣的保鲜效果。 相似文献
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本文应用人工神经网络中的BP网络与RBF网络,讨论脂肪醇催化剂配方的建模问题,并与传统的多元线性回归方法进行对比。结果表明,神经网络具有明显的优点,而RBF网络又比BF网络更加精确,且收敛速度要快1000倍以上。 相似文献
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为了研究生物质在水热降解过程中产物的分布及其液体产物特性,首先通过正交试验对生物质水热转化的工艺进行优化,根据不同的目标产物探索最优工艺条件,并对生物质样品的种类、反应温度、停留时间、原料质量和粒径等反应因素的变化规律进行研究,所得重质油产率最佳工艺条件是:采用松木屑为原料,温度250℃,停留时间15 min,原料质量10 g,水质量110 g,生物质粒径80~150目,此时松木屑的干基重质油产率(质量分数)为28.00%。最后结合正交试验结果,选取棉秆为原料,研究单因素反应条件(温度、时间、粒径以及催化剂)下产物产率分布和液体产物特性。结果表明,在无催化剂加入的试验中,温度300℃,停留时间10 min,粒径80~150目下棉秆重质油产率(质量分数)最大为24.14%;当K2CO3作为催化剂,停留时间为20 min时,重质油产率由未添加催化剂时的18.00%提高至29.86%,催化剂的加入在提高油产率的同时,对油的组份也产生了影响,酸类和酮类物质减少,油的p H值提高。 相似文献
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柴油机SCR后处理系统控制策略 总被引:3,自引:0,他引:3
国Ⅳ/Ⅴ柴油机采用SCR后处理技术相比其它技术有更多优势。为开发NH3-SCR后处理系统控制策略,采用试验与仿真相结合的方法,首先应用状态机理论设计SCR系统协调控制策略,并在Matlab平台中进行仿真测试,然后通过台架试验对建立的原机排放预估模型、催化器内部氨氮反应当量比计算模型和NH3目标覆盖度预估模型进行测试和标定,最后完成催化器载体瞬态温变滞后修正算法和瞬态工况NH3泄漏控制策略。设计的SCR控制系统瞬态工况的鲁棒性好,NOx转化率控制在60%左右,NH3泄漏平均值控制在1.0×10 -5 以下。将基于本系统控制策略的计量控制单元(DCU)应用到目标发动机,ESC和ETC试验测试的NOx比排放分别为3.01g/(kW·h)和3.15g/(kW·h),满足国Ⅳ标准。 相似文献
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介绍了催化湿式氧化技术的反应原理、工艺流程以及近些年来不同种催化剂的研究进展,分析和归纳了催化湿式氧化技术在污水处理中的应用现状,对实际应用中出现的问题进行了总结,并提出了一些建议。 相似文献