Oxygen-vacancy-rich MnO_(x)supported RuO_(x)for efficient base-free oxidation of 5-hydroxymethylfurfural and 5-methoxymethylfurfural to 2,5-furandicarboxylic acid

2,5-Furandicarboxylic acid(FDCA)is a promising biomass-derived polymeric monomer that serves as an attractive alternative to terephthalic acid derived from fossil resources.However,the green and efficient production of FDCA through the oxidation of 5-hydroxymethylfurfural(HMF)and its derivatives is still rudimentary under base-free conditions.In this work,oxygen-vacancy-rich Mn Oxwas prepared and displayed a strong adsorption and anchoring ability to Ru species that mainly exposed the(210)plane of RuO_(2),bringing about highly dispersed and active interfacial Ru-O-Mn structures.Experimental results and density functional theory calculations confirm that these above features greatly facilitate the adsorption/activation of oxygen and the dehydrogenation-oxidation of HMF/5-methoxymethylfurfural(MMF),which enables an efficient FDCA production under base-free and mild conditions.Notably,a desirable FDCA yield of 86.56%was still obtained from concentrated HMF(10 wt%)under base-free conditions over oxygen-vacancy-rich Mn Oxsupported Ru Ox(1.0 MPaO_(2),120℃,6 h).This work delineates a facile catalyst preparation strategy for HMF/MMF oxidation,and might open a new avenue for the green synthesis of FDCA under base-free conditions.

Selective oxidation of glycerol in a base-free aqueous solution: A short review

Catalytic transformation of glycerol to value-added products has attracted the attention of scientists all over the world. Among various transformations, selective oxidation of glycerol with molecular oxygen to dihydroxyacetone, glyceric acid, glyceraldehydes, and tartronic acid is challenging both from the viewpoint of academic research and industrial application. Herein, we review the recent progresses in the selective oxidation of glycerol under base-free conditions. Those catalysts widely reported for the selective oxidation of the terminal hydroxyl and secondary hydroxyl groups in glycerol, such as monometallic Au, Pt, and Pd NPs, and bimetallic Au-Pt, Au-Pd, Pt-Bi, Pt-Sb, and Pt-Cu, were compared and discussed in detail. The reaction mechanism over Pt-based catalysts, possible catalyst deactivation, and the corresponding improvements are presented. Further, the recent progresses in the continuous oxidation of glycerol in fixed bed reactors and its excellent selectivity in the formation of dihydroxyacetone are highlighted.

Selective oxidation of glycerol with oxygen in base-free solution over N-doped-carbon-supported Sb@PtSb2 hybrid

Selective oxidation of glycerol with molecular oxygen in base-free aqueous solutions has become a hot topic,as the rapidly increasing production of biodiesel is creating a surplus of glycerol.In this work,an N-doped-carbon-supported core-shell structured Sb@PtSb2 hybrid catalyst was prepared via a facile synthesis route,in which a mixture of glucose,melamine,and SbCl3(Sb-NC)was pyrolyzed,then impregnated with Pt by immersion in an aqueous solution of H2PtCl6,and further treated in hydrogen flow.Characterization of the catalyst products indicated that introducing SbCl3 can increase the surface area of the binary glucose+melamine pyrolyzed support(NC),and Sb@PtSb2 hybrids could be formed on the surface of an Sb-NC support during hydrogen treatment at 700℃.It was found that the Sb@PtSb2/NC catalyst was more active for the selective oxidation of glycerol in a base-free aqueous solution than Sb-free NC-supported Pt(Pt/NC).Further characterization also indicated that the promising performance of Sb@PtSb2/NC might be attributed to its enhanced oxygen activation.

Active sites of Pt/CNTs nanocatalysts for aerobic base-free oxidation of glycerol

Understanding the nature of Pt active sites is of great importance for the structure-sensitive base-free oxidation of glycerol. In the present work, the remarkable Pt particle size effects on glycerol conversion and products formation from the oxidation of the primary and the secondary hydroxyl groups are understood by combining the model calculations and DFT calculations, aiming to discriminate the corresponding dominant Pt active sites. The Pt(100) facet is demonstrated to be the dominant active sites for the glycerol conversion and the products formation from the two routes. The insights revealed here could shed new light on fundamental understanding of the Pt particle size effects and then guiding the design and optimization of Pt-catalyzed base-free oxidation of glycerol toward targeted products.

Highly efficient base-free aerobic oxidation of alcohols over gold nanoparticles supported on ZnO-CuO mixed oxides

The design and preparation of suitable supports are of great importance for gold catalysts to attain excellent catalytic performance for alcohol oxidation.In this work,we found that ZnO-CuO mixed oxides supported gold catalysts showed much better catalytic activity for base-free aerobic oxidation of benzyl alcohol than Au/ZnO and Au/CuO catalysts,and among them Au/Zn0.7Cu0.3O displayed the best catalytic performance.In addition,the Au/Zn0.7Cu0.3O catalyst could selectively catalyze the aerobic oxidation of a wide range of alcohols to produce the corresponding carbonyl compounds with high yields under mild conditions without base.Further characterizations indicated that the outstanding catalytic performance of Au/Zn0.7Cu0.3O was correlated with the small size of Au nanoparticles(NPs),good low-temperature reducibility,high concentration of surface oxygen species,and collaborative interaction between Au NPs and mixed oxide.

Copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids under ligand-free or both ligand-and base-free conditions

An efficient copper-catalyzed decarboxylative hydroboration of phenylpropiolic acids with bis（pinacolato）diboron was developed, affording b-vinylboronates as the only products in high yields. Extra hydrogen sources such as methanol are not needed in this catalytic system. This reaction could be performed successfully under ligand- and base-free conditions. It demonstrated that phenylpropiolic acids can be employed as alkyne synthons in the hydroboration reaction and exhibited good reactivity and higher selectivity than terminal alkynes.

Co(acac)_3/BMMImCl as a base-free catalyst system for clean syntheses of N,N'-disubstituted ureas from amines and CO_2

A base-free catalyst system Co(acac)3/BMMImCl was developed for the carbonylation of amines with CO2.45%-81% isolated yields for N,N'-dialkylureas and 6%-23% isolated yields for N,N-diarylureas were obtained.The catalyst system was recovered and reused without significant loss in activity.In this catalyst system,the base catalyst and chemical dehydrant were efficiently avoided.Different reaction conditions were also discussed and a postulated mechanism was proposed.

Base-free selective oxidation of monosaccharide into sugar acid by surface-functionalized carbon nanotube composites

Selective oxidation of biomass-derived monosaccharide into high value-added chemicals is highly desirable from sustainability perspectives.Herein,we demonstrate a surface-functionalized carbon nanotubesupported gold(Au/CNT-O and Au/CNT-N)catalyst for base-free oxidation of monosaccharide into sugar acid.Au/CNT-O and Au/CNT-N surfaces successfully introduced oxygen-and nitrogen-containing functional groups,respectively.The highest yields of gluconic acid and xylonic acid were 93.3%and 94.3%,respectively,using Au/CNT-N at 90℃ for 240 min,which is higher than that of using Au/CNT-O.The rate constants for monosaccharide decomposition and sugar acid formation in Au/CNT-N system were higher,while the corresponding activation energy was lower than in Au/CNT-O system.DFT calculation revealed that the mechanism of glucose oxidation to gluconic acid involves the adsorption and activation of O_(2),adsorption of glucose,dissociation of the formyl C-H bond and formation of O-H bond,and formation and desorption of gluconic acid.The activation energy barrier for the glucose oxidation over Au/CNT-N is lower than that of Au/CNT-O.The nitrogen-containing functional groups are more beneficial for accelerating monosaccharide oxidation and enhancing sugar acid selectivity than oxygen-containing functional groups.This work presents a useful guidance for designing and developing highly active catalysts for producing high-value-added chemicals from biomass.

Thermoresponsive block copolymer supported Pt nanocatalysts for base-free aerobic oxidation of 5-hydroxymethyl-2-furfural

A base-free catalytic system for the aerobic oxidation of 5-hydroxymethyl-2-furfural was exploited by using Pt nanoparticles immobilized onto a thermoresponsive poly(acrylamide-co-acrylonitrile)-b-poly(N-vinylimidazole)block copolymer,with an upper critical solution temperature of about 45°C.The Pt nanocatalysts were well-dispersed and highly active for the base-free oxidation of 5-hydroxymethyl-2-furfural by molecular oxygen in water,affording high yields of 2,5-furandicarboxylic acid(up to>99.9%).The imidazole groups in the block copolymer were conducive to the improvement of catalytic performance.Moreover,the catalysts could be easily separated and recovered based on their thermosensitivity by cooling the reaction system below the upper critical solution temperature.Good stability and reusability were observed over these copolymer-immobilized catalysts with no obvious decrease in catalytic activity in the five consecutive cycles.

The relationship of morphology and catalytic performance of CeO_(2) catalysts for reducing nitrobenzene to azoxybenzene under the base-free condition

CeO_(2) morphology was proposed to be a crucial factor for reducing nitrobenzene to azoxybenzene under the base-free condition.Herein,the structure-activity relationship of CeO_(2) catalysts was explored to improve the azoxybenzene yield.A series of CeO_(2) catalysts we re synthesized with seven morphologies to obtain different Ce^(3+) proportion and various surface areas.Notably,the catalytic performance of these samples for reducing nitrobenzene to azoxybenzene enhanced with the increasing Ce^(3+) proportio n.With the highest surface Ce^(3+) proportion,the Rod-CeO_(2) catalyst exhibited 100% conversion of nitrobenzene and 89.8% azoxybenzene selectivity in 7 h at 150℃ under 1 MPa CO.Moreover,the preliminary mechanistic analysis indicated that the inhabitation of azoxybenzene to by-product azobenzene resulted in the high selectivity of azoxybenzene.

增效型无土相仿生油基钻井液技术的研究与应用

针对深井超深井钻井过程中钻遇高温高压、井壁失稳及井下复杂情况的难题,基于仿生学、超分子化学以及岩石表面润湿性理论,通过优选仿生增效剂、仿生提切剂及仿生降滤失剂,配套相关处理剂,最终形成了一套适用于深井、超深井地层钻探的增效型无土相仿生油基钻井液体系。研究发现,建立的增效型无土相仿生油基钻井液体系可抗220℃高温,配制密度为2.4 g/cm^(3),破乳电压大于400 V,高温高压滤失量为3.2 mL,人造岩心在该体系中220℃下老化后的抗压强度达到7.1 MPa,平均渗透率恢复值为93.9%。现场应用情况表明,体系流变性能稳定,平均机械钻速比邻井提高16%,平均井径扩大率仅为1.25%,可有效解决深井超深井钻井过程中出现的井壁失稳难题,为我国深井超深井的钻探提供了技术保障。

基于镍基材料构建无酶比色传感器快速检测马拉硫磷

制备NiBM并将其应用无酶传感器的构筑,建立比色法快速检测马拉硫磷。合成的NiBM能将无色的3,3′,5,5′-四甲基联苯胺氧化为蓝色的TMB氧化物。当马拉硫磷存在时,由于NiBM中镍原子与马拉硫磷的硫代磷脂键之间具有高亲和力,NiBM与马拉硫磷相结合,抑制NiBM对TMB的氧化反应。该无酶NiBM传感器在最佳检测条件下表现出优异的稳定性和较高的检测性能,检测马拉硫磷的线性范围为0~100 ng·mL^(-1),检测限低至7.8 ng·mL^(-1)。所提出的比色传感器为有机磷农药的测定提供了一种有前景的快速检测技术,该技术使用的NiBM制备过程简单且原料廉价易得,有望应用于复杂基质中马拉硫磷的快速检测和通量筛查。

环氧树脂增强苯酚−尿素−乙二醛共缩聚树脂的粘接性能研究

为了改善乙二醛基树脂胶黏剂的胶合性能及耐水性,以环氧树脂(EPR)、苯酚(P)、尿素(U)、乙二醛(G)为原料,合成了一种新型EPR−PUG多元共缩聚树脂胶黏剂,探究树脂的基本性能、固化性能、胶合性能,以确定P/U/G摩尔比对树脂胶黏剂体系性能的影响和树脂胶黏剂的较佳合成配方。通过接触角、傅里叶变换红外光谱(FT−IR)、核磁共振碳谱(13C NMR)和X−射线光电子能谱(XPS)方法分析了共缩聚树脂胶黏剂的结构特征和合成机理。结果表明:原料的官能团之间发生了有效交联反应,分子间形成了致密的网络结构,致使树脂胶黏剂体系整体性能得以提升;在P∶U∶G摩尔比为0.1∶1.0∶1.5、反应pH为4~5、反应温度为70~80℃、反应时间3 h、EPR添加量为13%时,所制备的EPR−PUG共缩聚树脂胶黏剂制备的胶合板性能最佳,干/湿强度分别为2.48 MPa、1.33 MPa(冷水)及0.72 MPa(63℃热水),符合国标对II类胶合板的要求,且无甲醛释放。

以制度型开放创新为核心 高标准高质量推进中国(新疆)自贸试验区建设

在我国自贸试验区建设十周年之际,2023年10月国务院印发了《中国(新疆)自由贸易试验区总体方案》,正式批准设立中国(新疆)自由贸易试验区,使新疆成为我国第22个自贸试验区,也是我国西北边境地区首个自贸试验区。文章深入研究分析了新疆自贸试验区设立的重大意义,并就自贸试验区在拉动我国经济增长和实现高质量发展中的作用,制度创新在自贸试验区打造一流营商环境、提升现代产业国际竞争力等方面所发挥的作用和影响,以及制度型开放创新与逆全球化背景下深入实施自贸试验区提升战略的关系等问题进行了全面分析与思考。在此基础上,就如何以高水平开放为引领,以制度创新为核心,高标准高质量建设新疆自贸试验区提出了思路与对策建议。

纤维素基共聚型聚羧酸减水剂的合成及其性能

以天然纤维为原料,采用接枝醚化-烯丙基氯双键改性-水溶液自由聚合路线制备纤维素基共聚型聚羧酸减水剂(HEPCEs),通过傅里叶变换红外光谱、凝胶渗透色谱对产品HEPCEs进行分子结构分析,通过净浆流动度、经时变化流动度测试对HEPCEs减水性能进行评价,并同时进行了分子粒径、zeta电位以及吸附层厚度的测试,探究HEPCEs对水泥净浆的作用机理。结果表明,纤维素基共聚型聚羧酸减水剂中改性纤维素聚醚(DBHECs)适宜替代量为5%~10%,过多替代会出现支链缠绕并阻碍羧酸基团锚固,适量替代的纤维素结构引入可以在保持较好吸附性能的同时进一步提升减水剂的性能,超过商用高效减水剂标准,并表现出一定的缓释作用。

基于油基钻屑制备压裂支撑剂的室内研究

针对热解析后脱油钻屑处理难和处理方式单一的问题,开展了将油基钻屑残渣制备成免烧压裂支撑剂的研究,研究了钻屑与水泥比、CMC添加量、石膏添加量和养护天数共4个因素对免烧压裂支撑剂性能影响。结果表明,在原料配比较优的情况下,制备工艺为钻屑水泥比0.67(质量比),石膏添加量为6%(质量分数),CMC添加量为4%(质量分数),养护时间28 d。该条件下制得的压裂支撑剂颗粒体积密度为1.47 g/cm^(3),视密度为2.52 g/cm^(3),35 MPa下颗粒破碎率为1.57%。经扫描电子显微镜与X射线衍射仪分析发现,此时压裂支撑剂内部结构致密,孔隙封闭,水化产物CaO·SiO_(2)·nH_(2)O凝胶和钙长石类物质有利于提高压裂支撑剂的综合物理性能。为脱油钻屑残渣利用提供新的方向。

一种新型钾基磷酸盐无固相高密度封隔液

高温高密度封隔液是高温高压井完井关键技术之一,目前密度超过1.60 g/cm 3无固相盐水封隔液只有溴盐、锌盐或者甲酸铯溶液,溴盐毒性大,锌盐高温腐蚀性难以控制,而甲酸铯价格昂贵,难以满足高温高压井完井技术要求,开发针对高温高压井的新型无固相高密度清洁盐水封隔液势在必行。以磷酸三钾TKP为主剂并添加其他处理剂优化而成可溶性盐SW4,研发了一种新型钾基磷酸盐无固相高密度封隔液,测试了其密度调节能力、水溶液的流变性和流变模式、金属腐蚀性、高温稳定性、生物毒性等性能。结果表明,SW4封隔液常温条件下最大密度可达1.90 g/cm 3;随密度增大,其水溶液黏度上升,其流变模式为牛顿流体;密度1.85 g/cm 3的封隔液在150℃、7 d条件下对A3钢、N80钢、TN110Cr13S和TN110Cr13M钢的腐蚀速率均小于0.076 mm/a,N80钢在1.80 g/cm 3 SW4封隔液中的腐蚀性明显低于同等条件下的溴化钠、溴化钙和溴化锌,与甲酸铯相当;在同等加量条件下,SW4能够提供更多的K+,具有更优异的防膨性;高温稳定性强,能够满足高温高压井完井工况需求;生物毒性低,具有环境可接受性,可以满足作为无固相高密度封隔液加重剂的技术要求。

生物质基无铬鞣剂在可持续皮革制造中的研究进展

鞣制是使生皮变成革的关键工序。目前,铬鞣剂因其优良的性能仍占据鞣剂市场的90%。但是Cr3+存在转化为具有致癌性Cr6+的潜在危害,铬鞣废水的排放对生态系统的潜在风险不容忽视。因此,无铬鞣剂成为研究的热点。其中生物质材料因其来源广泛、可再生和生物可降解好等优点而备受关注。文章对多糖类、蛋白类等生物质材料进行了介绍,并对多糖、蛋白质的功能改性及其在皮革鞣制和复鞣的应用进行了归纳。同时,对生物质基鞣剂的发展前景及推广应用进行了展望。

Au/Cu-Co催化剂上甘油选择性氧化制二羟基丙酮的研究

二羟基丙酮(DHA)是甘油选择性氧化的高附加值产物,在农业、医药等领域具有重要的应用价值。本文以溶胶-凝胶法和硬模板法制备的CuO和Cu-Co金属氧化物复合材料为载体并负载金制备了催化剂,研究了其在非碱性条件下催化甘油氧化为二羟基丙酮的性能。活性评价结果表明,Au/Cu_(0.75)Co_(0.25)催化剂具有最高的催化活性,表现出了良好的选择性,在最佳的反应条件下,甘油转化率为69.0%,DHA选择性为99.7%,催化剂较高的活性可能是由于Co的加入增强了Au与载体之间的相互作用,使得电子云密度更容易向Au发生偏移从而形成更多的Au^(0)物种并且提高了Au的颗粒分散度,Au^(0)的增加有利于形成更多的晶格氧物种O_(latt),从而增强了甘油的活化和转化,更小的Au粒径也有利于催化剂上甘油的吸附和活化,从而促进了DHA的生成。

无甲醛浸渍胶膜纸用涂布型装饰原纸的制备及性能

【目的】针对现有无醛胶黏剂在纸张内部渗透性较差以及一定程度上遮盖原纸色泽和纹理的问题,从装饰原纸性能着手,采用浆内填料加填结合表面颜料化涂布对装饰原纸进行处理,在保证纸张对胶液的渗透性、吸收性前提下,提高纸张的印刷适性和遮盖力,降低无醛胶黏剂对装饰纸饰面效果的影响,为制备适用的无醛装饰纸提供方法。【方法】选用优质阔叶木浆和针叶木浆进行原纸抄造,浆内填料(TiO_(2))含量设为20%、30%和40%,利用二氧化硅(SiO_(2))和聚乙烯醇(PVA)混合液对3种不同加填量的原纸进行涂布、压光整饰得涂布型装饰原纸。采用聚氨酯类无醛胶黏剂对涂布型装饰原纸进行浸渍处理,继而固化和热压贴面。使用扫描电子显微镜(SEM)和动态渗透性测定仪对装饰原纸的表面状态和动态渗透性进行表征测试,应用喷墨打印机对装饰原纸进行印刷打样,通过分光密度计结合相对反差的计算分析装饰原纸的印刷性能,测试分析装饰原纸的抗张强度、平滑度、透气度、吸水性、白度等物理性能以及装饰纸贴面板的表面耐磨性、表面硬度和表面胶合强度等性能。【结果】浆内填料加填量增加会使填料更多填充到原纸结构空隙中,影响胶液在纸张内部的渗透性,致密的表面涂层也会一定程度上降低胶液在纸张内部的渗透性。未涂布原纸的色密度随浆内填料加填量增加而下降,涂布原纸的青、品红、黄、黑色实地密度较未涂布原纸分别提高69.0%、96.2%、45.6%、86.5%,品红、黄、黑3种色别的相对反差均达到标准要求。涂布对装饰原纸的印刷适性起积极作用,填料加填量变化对涂布后装饰原纸印刷适性的影响并不显著;填料加填量增加致使装饰原纸的抗张强度、吸水性下降,平滑度、紧度、白度提高,涂布后装饰原纸较未涂布原纸抗张强度提高52.8%,平滑度提高97.56%,白度变化不明显,不透明度稍有提高;热压后涂布型无醛浸渍胶膜纸的表面耐磨性、硬度和表面胶合强度均达到标准要求。【结论】减少装饰原纸浆内填料加填量,辅以表面涂布方式,能够提高装饰原纸的物理性能以及印刷适性,该方式生产的装饰原纸适用于无醛胶黏剂浸渍,有利于装饰纸无醛化发展。