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游离和溶胶-凝胶固定化甲醛脱氢酶酶促反应动力学的研究 总被引:1,自引:0,他引:1
采用溶胶-凝胶法对甲醛脱氢酶进行固定化,酶的包埋率超过了98%.在pH7附近、37℃下,以游离酶和固定化酶作催化剂,NADH为电子供体,进行了甲酸转化为甲醛的酶促反应.游离和固定化甲醛脱氢酶酶促反应都遵循Michaelis-Menten反应机理,用Dalziel提出的双底物酶促反应动力学方程进行拟合.固定化酶酶促反应速率为游离酶酶促反应速率的50%左右.固定化酶的动力学常数φ和米氏常数K高于游离酶,估计是凝胶基质孔中存在扩散效应所致. 相似文献
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溶胶凝胶包埋吡啶羧酸钴及其对甲醇氧化羰化反应的催化性能 总被引:9,自引:0,他引:9
以正硅酸乙酯为前驱体,采用溶胶-凝胶技术将吡啶羧酸钴包埋进SiO2基体中,于80℃干燥12h后得到钴含量为2.8%(Co/Si摩尔比)的干凝胶催化剂.采用FT-IR和TG-DTA方法对包埋催化剂进行了表征,考察了成胶过程中的pH和水与正硅酸乙酯的摩尔比(R)对包埋催化剂的结构及其对甲醇氧化羰化制碳酸二甲酯反应催化性能的影响.结果表明,干凝胶催化剂有较高的比表面积(320~458m2/g).在酸性条件下,增大pH或减小R值可缩短成胶时间.最佳的包埋条件是pH=4,R=6,在此条件下制备的凝胶包埋催化剂的活性最高,反应3h,甲醇转化率为5.73%,略低于均相催化剂上的甲醇转化率.但凝胶包埋催化剂分离简便,且重复使用6次后活性保持不变. 相似文献
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研制了一种用溶胶 凝胶技术包埋电活性物质的银离子选择电极。研究了包埋过程的变量参数及电极的响应机理。电极Nernst响应范围为 1.0× 10 - 1~ 1.0× 10 - 5mol·L- 1,斜率为5 5 .5mV·pc- 1,检出限为 3.1× 10 - 6mol·L- 1。该电极响应快 ,体积小 ,制作简单 ,使用方便 ,具有坚固耐磨 ,可在严酷条件下使用的特点。此研究对进一步研制溶胶 凝胶ISFET化学传感器和生物传感器具有探索意义 相似文献
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多孔陶瓷膜与溶胶-凝胶方法 总被引:1,自引:0,他引:1
一、简介膜如同国界,界两边既相联系又相隔离,选择性通过是其基本特征。国界的选择性由关卡完成,而膜是通过特定的孔道来实现,故孔道的不同决定了膜有不同的用途。分离是膜的最基本的应用。同其他方法相比,膜分离具有能耗低、选择性高、可在常温下进行等显著优点。 相似文献
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二氧化碳和甲醇合成碳酸二甲酯研究进展 总被引:10,自引:0,他引:10
本文综述了以二氧化碳和甲醇为起始原料合成碳酸二甲酯(DMC)的研究状况。提出以CO2和甲醇直接合成DMC,不仅对合成化学,碳资源利用和环境保护具有重大意义,而且可使生产成本显著降低,它是发展DMC生产的一个具有很大潜力的方面。 相似文献
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Dr. Katerina Sordakis Dr. Akihiro Tsurusaki Dr. Masayuki Iguchi Prof. Hajime Kawanami Dr. Yuichiro Himeda Prof. Gábor Laurenczy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15605-15608
Carbon dioxide may constitute a source of chemicals and fuels if efficient and renewable processes are developed that directly utilize it as feedstock. Two of its reduction products are formic acid and methanol, which have also been proposed as liquid organic chemical carriers in sustainable hydrogen storage. Here we report that both the hydrogenation of carbon dioxide to formic acid and the disproportionation of formic acid into methanol can be realized at ambient temperature and in aqueous, acidic solution, with an iridium catalyst. The formic acid yield is maximized in water without additives, while acidification results in complete (98 %) and selective (96 %) formic acid disproportionation into methanol. These promising features in combination with the low reaction temperatures and the absence of organic solvents and additives are relevant for a sustainable hydrogen/methanol economy. 相似文献
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Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbon Dioxide 总被引:7,自引:0,他引:7
Introduction Dimethyl carbonate (DMC) is an important carbon-ylating and methylating agent substituting dimethyl sul-fate and toxic phosgene, and an intermediate for higher carbonates and carbamates.1 In addition, it is also a promising octane enhancer.2 The widely used method of its preparation is the oxidative carbonylation of metha-nol by carbon monoxide with copper(II) or palladium(II) catalysts.3 Recently, the utilization of carbon dioxide as the raw material for DMC synthesis has bee… 相似文献
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采用溶胶-凝胶法制备了n(Cu):n(Zr)=1:1、1:2、1:4和1:8的Cu/ZrO2催化剂。 实验结果表明,当n(Cu):n(Zr)=1:4时,催化剂表现出较高的CO2转化率(8.0%)和甲醇选择性(59.5%),为了增加CO2的转化率,提高甲醇选择性,在n(Cu):n(Zr)=1:4的催化剂中添加质量分数1%的Pd,采用浸渍法制备了Pd-Cu/ZrO2催化剂。 在250 ℃、2 MPa、12000 mL/(g·h)和V(H2):V(CO2)=3:1的反应条件下,CO2转化率和CH3OH收率相比Cu/ZrO2催化剂(n(Cu):n(Zr)=1:4)分别提高了40.0%和80.9%。 通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、N2吸附-脱附(BET)、X射线光电子能谱仪(XPS)和程序升温还原化学吸附仪(H2-TPR)等仪器表征证明Pd的添加提高了催化剂的分散性和比表面积。 催化剂中Pd和Cu之间强相互作用,使Cu2p轨道结合能向低处偏移,还原温度的降低,说明Pd-Cu/ZrO2催化剂还原能力增强,使得CO2加氢活性提高。 相似文献
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Cu/Zn/TiO2负载型催化剂上CO2加氢合成甲醇 总被引:1,自引:0,他引:1
采用溶胶-凝胶法和浸渍法制备Cu/Zn/TiO2负载型催化剂,研究了不同Cu、Zn负载量对催化剂性能的影响,采用BET、XRD、TPR对催化剂进行了表征.考察了反应温度、压力和催化剂组成对CO2加H2催化合成甲醇的影响. 相似文献
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Rapid Selective Electrocatalytic Reduction of Carbon Dioxide to Formate by an Iridium Pincer Catalyst Immobilized on Carbon Nanotube Electrodes 下载免费PDF全文
Dr. Peng Kang Dr. Sheng Zhang Prof. Thomas J. Meyer Prof. Maurice Brookhart 《Angewandte Chemie (International ed. in English)》2014,53(33):8709-8713
An iridium pincer dihydride catalyst was immobilized on carbon nanotube‐coated gas diffusion electrodes (GDEs) by using a non‐covalent binding strategy. The as‐prepared GDEs are efficient, selective, durable, gas permeable electrodes for electrocatalytic reduction of CO2 to formate. High turnover numbers (ca. 54 000) and turnover frequencies (ca. 15 s?1) were enabled by the novel electrode architecture in aqueous solutions saturated in CO2 with added HCO3?. 相似文献
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二氧化碳存在下甲烷氧化细菌催化甲烷生物合成甲醇 总被引:6,自引:0,他引:6
在甲烷单加氧酶和脱氢酶系的作用下,甲烷氧化细菌Methylosinus trichosporium IMV 3011可以把甲烷氧化成二氧化碳. 在反应体系中充入一定比例的二氧化碳后,检测到了甲醇的积累. 混合气中CO2,CH4,O2和N2的体积比为2∶1∶1∶1时甲醇的积累量达到最大. 在超滤膜反应器中进行了连续反应,利用反应混合气产生的压力将生成的甲醇从反应体系中分离. 连续反应198 h后甲醇的积累量没有明显下降. 相似文献
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Siti Nurhanna Riduan Yugen Zhang Dr. Jackie Y. Ying Prof. 《Angewandte Chemie (International ed. in English)》2009,48(18):3322-3325
Activate and reduce : Carbon dioxide was reduced with silane using a stable N‐heterocyclic carbene organocatalyst to provide methanol under very mild conditions. Dry air can serve as the feedstock, and the organocatalyst is much more efficient than transition‐metal catalysts for this reaction. This approach offers a very promising protocol for chemical CO2 activation and fixation.
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Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Potassium Hydroxide under Mild Conditions 总被引:2,自引:0,他引:2
Hong WANG Bin LU Qing Hai CAI Feng WU Yong Kui SHAN 《中国化学快报》2005,16(9):1267-1270
The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results showed that KOH is an effective catalyst; the high selectivity and raised yield of DMC formation under mild conditions were achieved. However, the addition of the ionic liquid, l-ethyl-3-methylimidazolium bromide (emimBr), can evidently accelerate the conversion of methanol and yield of the product. 相似文献