Enhancing photo-generated carriers transfer of K-C_(3)N_(4)/UiO-66-NH_(2) with Er doping for efficient photocatalytic oxidation of furfural to furoic acid

Biomass-derived platform molecules,such as furfural,are abundant and renewable feedstock for valuable chemical production.It is critical to synthesize highly efficient photocatalysts for selective oxidation under visible light.The Er@K-C_(3)N_(4)/UiO-66-NH_(2) catalyst was synthesized using a straight-forward hydrothermal technique,and exhibited exceptional efficiency in the photocatalytic oxidation of furfural to furoic acid.The catalyst was thoroughly characterized,confirming the effective adjustment of the band gap energy of Er@K-C_(3)N_(4)/UiO-66-NH_(2).Upon the optimized reaction conditions,the conversion rate of furfural reached 89.3%,with a corresponding yield of furoic acid at 79.8%.The primary reactive oxygen species was identified as·O_(2)^(-) from ESR spectra and scavenger tests.The incorporation of Er and K into the catalyst enhanced the photogenerated carriers transfer rate,hence increasing the separating efficiency of photogenerated electron-hole pairs.This study expands the potential applications of rare earth element doped g-C_(3)N_(4) in the photocatalytic selective oxidation of furfurans.

Linear paired electrolysis of furfural to furoic acid at both anode and cathode in a multiple redox mediated system

Implementing a new energy-saving electrochemical synthesis system with high commercial value is a strategy of the sustainable development for upgrading the bulk chemicals preparation technology in the future.Here,we report a multiple redox-mediated linear paired electrolysis system,combining the hydrogen peroxide mediated cathode process with the I2 mediated anode process,and realize the conversion of furfural to furoic acid in both side of the dividedflow cell simultaneously.By reasonably controlling the cathode potential,the undesired water splitting reaction and furfural reduction side reactions are avoided.Under the galvanostatic electrolysis,the two-mediated electrode processes have good compatibility,which reduce the energy consumption by about 22%while improving the electronic efficiency by about 125%.This system provides a green electrochemical synthesis route with commercial prospects.

Synthesis and Crystal Structure of N-(1-Phenyl-3methyl-4-benzal-pyrazolone-5)-furoic Hydrazide

N-(1-Phenyl-3-methyl-4-benzal-pyrazolone-5)-furoic hydrazide (PMBP-FUH, C22H18N4O3, CCDC No: 188946) has been synthesized and characterized by IR spectrum, 1H NMR and single-crystal X-ray diffraction. The crystal is of orthorhombic, space group Pbca with a = 11.870(2), b = 15.951(3), c = 19.674(3) ? V = 3725.0(11) ?, Mr = 386.40, Z = 8, Dc = 1.378 g/cm3, F(000) = 1616, R = 0.0455 and wR = 0.0809. The inter- or intramolecular hydrogen bonds result in the formation of three-dimensional network structure.

Electrochemical conversion of furfural to furoic acid:a more stable,efficient and energy-saving system

The paired electrolytic system is constructed by combining the valuable organic electro-oxidation and electro-reduction reactions,which can replace the ineffective water splitting half-reaction.By reducing the energy consumption of the electrolytic cell,the value-added electrolysis is realized.The indirect electrolysis method greatly reduces the dependence of the organic electrolysis reaction on electrode potential by introducing the redox mediators,which solves the problem on the matching of anode and cathode current under potentiostatic conditions.Here,we report a more stable,efficient and energy-saving linear paired electrochemical synthesis system that can simultaneously convert furfural to furoic acid at both the anode and cathode at higher current densities.Stable three-dimensional networked PbO_(2)is used as the anode and the catalytic amount of 2,2,6,6-tetramethyl-1-piperidinyloxy(TEMPO)is used as the mediator to realize the efficient conversion of furfural to furoic acid in a wide potential range.The cathode catalyzes two-electron oxygen reduction to hydrogen peroxide using Pb/RHPC gas-diffusion electrode,which mediates the oxidation of furfural to furoic acid simultaneously.In potentiostatic electrolysis,the selectivity of the furoic acid in the cathode and anode is 33.2%and 99.3%,respectively,and the total electron efficiency is 127.1%.The properties of the cathode and anode remain stable after the long-time electrolysis in a flow cell.By choosing a stable anode with high oxygen evolution overpotential and a gas-diffusion cathode with high hydrogen evolution overpotential,the electrolytic cell can be operated efficiently and stably by introducing reasonable mediated reactions.The two half-reactions have good compatibility during the electrolysis process,saving energy consumption by about 12.3%,for certain industrial application prospects.

Electrodeposited 3D hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol

A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable development.Herein,the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol(FFA)into furoic acid(FurAc)catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient pressure.The 3D hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper(CFP).Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA(FFAOR)than oxygen evolution reaction(OER).The linear sweep voltammetry(LSV)in FFAOR displayed a clear decrease towards lower potential,resulting in 30 mV reduction of overpotential at 20 mA cm^(-2) compared with that of OER.The optimal catalyst Ni_(1)Fe_(2) nanosheets exhibited the highest selectivity of FurAc(94.0%)and 81.4%conversion of FFA within 3 h.Besides,the influence of various reaction parameters on FFAOR was then explored in details.After that,the reaction pathway was investigated and rationally proposed.The outstanding performance for FFAOR can be ascribed to the unique structure of 3D flower-like NiFe nanosheets and oxygen vacancies,resulting in large exposure of active sites,faster electron transfer and enhanced adsorption of reactants.Our findings highlight a facile and convenient mean with a promising green future,which is promising for processing of various biomass-derived platform chemicals into value-added products.

糠酸制备生物质基2,5-呋喃二甲酸的研究进展

2,5-呋喃二甲酸(FDCA)作为一种绿色的生物基平台化合物,可广泛应用于聚酯、塑化剂、消防及医药等领域。目前,根据合成FDCA的原料区分,FDCA合成路线分为5-羟甲基糠醛(HMF)路线、糠酸路线和其他原料路线。其中糠酸可由大宗生物质基化学品糠醛氧化制备,糠醛工业化生产使得糠酸制备FDCA路线具有绿色、经济性高的优势。据此,综述了糠酸制备FDCA的4种方法:歧化法、羰基化法、C—H羧基化法以及生物催化法的研究现状,对比分析了各方法的优劣及研究进展。通过对比分析表明:C—H羧基化法是一种反应条件温和、绿色环保的工艺,具有实现规模化生产的潜力。

生物基2,5-呋喃二甲酸的绿色合成技术综述

生物基芳香二酸2,5-呋喃二甲酸(2,5-furandicarboxylic acid,FDCA)有望部分替代石油基二酸对苯二甲酸(terephthalic acid,PTA)用于高性能高分子材料的合成.本文综述了从5-羟甲基糠醛(5-hydroxymethylfurfural,HMF)、糠酸、呋喃、二甘醇酸、己糖二酸、2,5-二甲基呋喃和2-甲基呋喃制备FDCA的各路线,并详细介绍了HMF的直接氧化法、多相热催化氧化法、光电催化氧化法以及糠酸羧基化、歧化、羰基化等策略合成FDCA.在比较了各路线优缺点的基础上,认为HMF路线和糠酸路线是FDCA规模化生产最有希望的路线,提出未来应在改进催化路线、简化反应工艺、提高分离效率、减少三废含量等方面进行更为深入的探索和研究.

糠酸分解反应动力学与机理研究

己糖二酸脱水环合制备2,5-呋喃二甲酸(2,5-FDCA)是一条有工业发展潜力的工艺。针对该工艺母液循环过程中杂质成分不确定、副产物糠酸分解反应动力学和机理不清楚等问题,在糠酸分解产物明确的基础上,测定了糠酸在4种催化体系中的分解反应动力学和分解产物的生成反应动力学。结果表明,在不同催化体系中糠酸的分解速率由快到慢依次为:10%H_(2)SO_(4)、3%HBr+2%MgBr2、3%HBr、3%HBr+2%LiBr(百分数均为质量分数)。采用1级反应动力学拟合得到糠酸在2%HBr+5%LiBr催化下的分解反应活化能为98.74 kJ·mol^(-1)。提出了糠酸分解的可能路径为糠酸先脱羧生成呋喃,呋喃再通过Diels-Alder反应生成相对稳定的2,3-苯并呋喃,2,3-苯并呋喃可与呋喃通过Diels-Alder反应进一步生成氧芴。

香料糠酸甲酯的新法合成与表征

从糠醛出发 ,由制备的糠酸和甲醇反应 ,在盐酸催化下 ,合成了香料糠酸甲酯 ,并用IR、1HNMR、GC等进行了表征 ;探讨了包括高纯度糠酸的制备在内的反应影响因素 ,在醇酸物质的量之比为 5∶1、催化剂体积占甲醇体积 13.0 %、反应时间 3h的最佳工艺条件下 ,酯化收率为81 0 % ,收率比硫酸法。

PTC法合成5-芳基-2-呋喃甲酸四乙酰葡萄糖酯

采用ＰＴＣ法合成了４个５－芳基－２－呋喃甲酸四乙酰葡萄糖酯，通过元素分析、ＩＲ、＾１ＨＮＭＲ及ＭＳ确证了糖酯的结构，并试验了所合成的糖酯的杀菌活性。通过对糖酯化合物的＾１ＨＮＭＲ谱图中糖环碳１位质子的化学位移及偶合常数分析，结合ＩＲ谱图中糖环Ｃ１－Ｈ的弯曲振动吸收，确证它们均为β型异构体。

反相高效液相色谱法测定糠酸、糠醇和糠醛

提出了反相高效液相色谱法(HPLC)同时测定糠酸、糠醇和糠醛的新方法,采用C18色谱柱,流动相为V(乙腈)∶V(水)=50∶50,流速为1.0 mL/min;检测波长为220 nm;柱温为25℃。在4 min内可以将3种组分完全分离。糠酸、糠醇、糠醛检出限(S/N=3)分别为:0.101、0.042、0.406 mg/L。平均回收率分别为101.4%、98.5%、95.3%。相对标准偏差(RSD)分别为0.87%、0.66%、0.43%。

糠酸莫米松鼻喷雾剂对变应性鼻炎患儿鼻腔黏液菌群的影响

目的探讨糠酸莫米松鼻喷雾剂对儿童变应性鼻炎鼻腔黏液菌群的影响,并观察其临床疗效。方法选取我院门诊治疗的49例变应性鼻炎儿童患者作为治疗组,给予糠酸莫米松治疗,同时对其治疗前后鼻腔黏液的菌群分布情况进行检测,另设立48例未患变应性鼻炎的正常儿童为对照组进行比较。结果治疗组患者经糠酸莫米松治疗后鼻部症状、眼部症状、呼吸道症状评分均较治疗前明显降低(P<0.05),治疗组治疗后鼻部症状、眼部症状、呼吸道症状得分均高于对照组(P<0.05)。经检测发现,对照组病原菌检出率为91.7%,其中需氧菌和真菌各占82.4%和17.6%,而治疗组治疗前病原菌检出率为91.8%,需氧菌和真菌各占79.6%和20.4%,治疗后病原菌检出率为93.9%,其中需氧菌和真菌各占85.4%和14.6%,其中需氧菌以凝固酶阴性葡萄球菌居首位,真菌则以曲霉菌居首位。但对照组与治疗组治疗前以及治疗组治疗前后比较差异均无统计学意义(P>0.05)。结论糠酸莫米松鼻喷雾剂治疗儿童变应性鼻炎对改善患儿的临床症状有较好效果,但对鼻腔黏液菌群不产生明显影响。

2,5-呋喃二甲酸的合成

以糠酸为原料,经过酯化、氯甲基化、水解、氧化得到2,5-呋喃二甲酸,并对各步反应中的工艺参数进行了优化。优化结果:酯化反应时间为10 h,氯甲基化反应温度为35～40℃,水解反应原料摩尔比为n(氢氧化钠)∶n(5-氯甲基-2-呋喃甲酸甲酯)=2.1∶1,氧化反应体系pH=7～8,反应总收率47.5%。按该工艺顺利完成了3次20 L扩试反应,平均收率可达47.3%,产品HPLC纯度大于99.4%。

Ni-P-mCMC/mCS双极膜技术在成对电解制备糠醇、糠酸中的应用

以磷酸化试剂改性羧甲基纤维素钠(mCMC)制备了阳膜层,以戊二醛改性壳聚糖(mCS)制备了阴膜层溶胶,将阴膜层溶胶流延于阳膜层上,制备了P-mCMC/mCS双极膜,而后以化学镀方法在阳膜层表面镀镍,制备了Ni-P-mCMC/mCS双极膜,并应用于成对电合成糠醇(阴极室中)、糠酸(阳极室中)。在电场的作用下,双极膜中水电离后生成的H+透过mCMC阳离子膜进入阴极室,促进糠醛电还原生成糠醇过程的进行;OH-透过mCS阴离子膜进入阳极室,与糠醛电氧化生成糠酸过程中产生的H+结合生成H2O,以增大正向反应的速度。在电流密度为2.5×10-2A/cm2,30℃下电解,阴阳两极室的电解效率分别为83.0%和77.4%,电解槽电压稳定在3.0V左右。

反相液液微萃取/高效液相色谱测定变压器油中糠酸的含量

以水为萃取剂,建立了变压器油中糠酸含量的反相液液微萃取/高效液相色谱测定方法。通过研究萃取剂的p H值、萃取剂体积、稀释剂用量、萃取时间及离心转速的影响,确定了最优的萃取条件。结果表明：在以中性水为萃取剂,萃取剂体积为150μL,稀释剂比例V油∶V正己烷为3∶1,涡旋萃取时间为5 min,离心转速为5 500 r/min的条件下,水萃取相直接用于高效液相色谱测定,变压器油中糠酸的浓度在0.05-5.00 mg·L^-1范围内呈良好线性,相关系数（r）为0.9999,方法的检出限为9.6μg·L^-1,相对标准偏差（RSD,n=6）为1.4%,糠酸的富集倍数为13.6倍。实际老化样品测定的加标回收率为99.7%-105.1%,并对样品中的糠酸进行了HPLC-MS定性分析。该方法简捷有效,为变压器油纸绝缘老化特征量的研究提供了数据支持。

润滑油精制装置中的防腐与防焦研究

阐明了润滑油精制装置中的糠醛腐蚀及生焦机理。根据工艺流程的特点，采用注入有机胺类缓蚀剂等措施，可破坏糠醛、糠酸和水的共沸，阻止糠酸从糠醛回收塔返回装置系统，结果使全装置酸值下降，同时使全装置的腐蚀及焦生成量减少，装置开工周期从一年延长至两年半。

水溶剂中Pd-Ni/γ-Al_2O_3催化剂上糠酸加氢

制备了Pd-N i/γ-A l2O3催化剂,应用程序升温还原和程序升温脱附技术考察了催化剂的表面性质与催化加氢性能的关系。实验结果表明,Pd-N i/γ-A l2O3催化剂表面存在两种活性中心,催化加氢反应主要在较弱的活性中心上进行。采用连续流动固定床微型反应器考察了水溶剂体系中Pd-N i/γ-A l2O3催化剂上糠酸加氢生成四氢糠酸的反应,研究了反应条件对催化反应性能的影响,在2.5M Pa、200℃、氢气空速4 000h-1、糠酸水溶液的空速8.0h-1、氢气与糠酸的摩尔比50的条件下,糠酸转化率为96.8%,四氢糠酸选择性为100%,催化剂连续运转200h后催化活性没有下降。

α-呋喃酯的结构与红外光谱特征

总结和归属了α－呋喃甲酸酯、α－呋喃甲醇酯和α－呋喃丙烯酸酯的主要红外吸收谱带和特征，讨论了其红外吸收频率随取代基结构而变化的规律。结果表明：α－呋喃环存在三个明显的吸收特征。α－呋喃丙烯酸酯中νＣ＝Ｃ约为１６４１ｃｍ－１，δ＝Ｃ—Ｈ面外变角振动频率为９７３ｃｍ－１，表明双键为反式构型。νＣ＝Ｏ约为１７１３ｃｍ－１，ＯＣＣ键对称与不对称伸缩振动在１３０５，１２６２和１１６５ｃｍ－１处产生三个强的特征吸收峰。

模拟酶微型反应器中糠醛催化氧化为糠酸

在水与有机试剂组成的非均相体系中 ,用 β 环糊精 (β cyclodextrin ,缩写 :β CD)衍生物模拟生物酶 ,以强力搅拌下分散在有机溶剂中的小水珠作为微型反应器进行糠醛催化氧化为糠酸的反应 ,停止搅拌后体系立即分层 ,产物在有机相 ,残留的原料和模拟酶在水相。本合成方法简单 ,溶剂和模拟酶能回收 ,不产生污染 ,催化效率较均相高 ,为绿色合成化学制备医药。

香料糠酸乙酯的合成研究

糠酸乙酯是一种已在美国、日本等国家批准使用的新型香料。利用新蒸馏过的糠醛发生歧化反应制得糠酸,并找出了影响糠酸纯度的因素。用自制的糠酸和乙醇为原料,硫酸氢钠为催化剂通过酯化反应催化合成糠酸乙酯。硫酸氢钠是一种价廉、易得的无机晶体,对设备的腐蚀减小,对环境无污染,且能够回收和重复使用,减少了操作步骤,降低了成本。运用正交试验方法,考察了物料的摩尔比、催化剂用量、反应时间等对转化率的影响,实验结果表明,影响糠酸转化率的主要因素是糠酸与乙醇的摩尔比和反应时间,次要因素是催化剂用量,合成糠酸乙酯的最佳工艺条件是糠酸与乙醇的摩尔比为1∶5,一水合硫酸氢钠用量为0.15g(相对于0.1mol糠酸),反应时间4h,糠酸的转化率达到84.4%。